Domestic Animal Endocrinology - Articles in Press

Lipopolysaccharides, cytokines, and nitric oxide affect secretion of prostaglandins and leukotrienes by bovine mammary gland epithelial cells - Corrected Proof

2012-05-21

Abstract: The aims of this study were to determine the effects of lipopolysaccharides (LPS), tumor necrosis factor (TNF), interleukin 1 alpha (IL-1α), nitric oxide donor (NONOate), or the combination of TNF + IL-1α + NONOate on the following: (i) secretion of prostaglandin (PG)-F2α, PGE2, leukotriene (LT)-B4, and LTC4 by epithelial cells of the teat cavity and lactiferous sinus of bovine mammary gland; (ii) messenger RNA (mRNA) transcription of enzymes responsible for arachidonic acid (AA) metabolism (prostaglandin-endoperoxide synthase 2 [PTGS2], prostaglandin E synthase [PTGES], prostaglandin F synthase [PGFS], and arachidonate 5-lipooxygenase [ALOX5]); and (iii) proliferation of the cells. The cells were stimulated for 24 h. Prostaglandins and LT were measured by enzyme immunoassay, mRNA transcription of enzymes was determined by real-time reverse transcription polymerase chain reaction, and the cell viability was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. All factors increased PG secretion, but the highest stimulation was observed after TNF and IL-1α (P < 0.001). Tumor necrosis factor, NONOate, and TNF + IL-1α + NONOate increased LTB4 production (P < 0.01), whereas LTC4 was increased by LPS, TNF, and IL-1α (P < 0.01). Lipopolysaccharides, TNF, IL-1α, and the reagents combination increased PTGS2, PTGES, and PGFS mRNA transcription (P < 0.01), whereas ALOX5 mRNA transcription was increased only by TNF (P < 0.001). Lipopolysaccharides, TNF, IL-1α, NONOate, and the combination of reagents increased the cell number (P < 0.001). Mediators of acute-clinical Escherichia coli mastitis locally modulate PG and LT secretion by the epithelial cells of the teat cavity and lactiferous sinus, which might be a useful first line of defense for the bovine mammary gland. Moreover, the modulation of PG and LT secretion and the changing ratio of luteotropic (PGE2, LTB4) to luteolytic (PGF2α, LTC4) metabolites may contribute to disorders in reproductive functions.

Effects of stress on endocrine and metabolic processes and redirection: cross talk between subcellular compartments - Corrected Proof

T.H. Elsasser, S. Kahl, A.V. Capuco, W. Schmidt — 2012-05-21

Abstract: Recent advances in genome analysis and biochemical pathway mapping have advanced our understanding of how biological systems have evolved over time. Protein and DNA marker comparisons suggest that several of these systems are both ancient in origin but highly conserved into today's evolved species. However, remnants of some of the more ancient functions of these chemical systems can run in conflict with the functions that those same pathways serve in complex organisms and tissue systems today. Relevant to the present topic, nitric oxide (NO) and superoxide anion (O2•−), ancient cellular molecules in evolutionary terms, are recognized today as both necessary for the well-being and stable health of cells but also injurious to cells as elaborated in conjunction with the cellular stress response. Why the dichotomy? This question underlies one of the basic issues challenging researchers as well as practitioners in their approach to disease management. The fundamental proinflammatory response of the innate immune system of the host is needed for pathogen control but can be injurious to tissues from “collateral damage” from NO- and O2•−-derived reactive molecules capable of affecting protein function via post-translational chemical modification. This review highlights newer aspects of the biochemistry of the NO- and O2•−-mediated innate proinflammatory response and further show how protein and tissue damage via overproduction of reactive nitrogen and oxygen intermediary molecules such as peroxynitrite (ONOO−) might be targeted to specific epitopes of proteins. Changes in the regulation of metabolism in response to proinflammatory disease states are discussed for GH signal transduction and tissue specificity.

Serotonin as a homeostatic regulator of lactation - Corrected Proof

R.J. Collier, L.L. Hernandez, N.D. Horseman — 2012-05-18

Abstract: Serotonin (5-HT), a neurotransmitter produced in mammary epithelial cells (MECs), acts via autocrine–paracrine mechanisms on MECs to regulate milk secretion in a variety of species. Recent studies in dairy cows reported that 5-HT ligands affect milk yield and composition. We determined the mRNA expression of bovine 5-HT receptor (5-HTR) subtypes in bovine mammary tissue (BMT) and cultured bovine MECs. We then used pharmacologic agents to evaluate functional activities of 5-HTR subtypes. The mRNAs for five receptor isoforms (5-HTR1B, 5-HTR2A, 5-HTR2B, 5-HTR4, and 5-HTR7) were identified by conventional reverse transcription PCR, real-time PCR, and in situ hybridization in BMT. In addition to luminal MEC expression, 5-HTR4 was expressed in myoepithelium, and 5-HTR1B, HTR2A, and HTR2B were expressed in small mammary blood vessels. Studies to date report that there are multiple 5-HTR isoforms in mammary tissue of rodents, humans, and cattle. Inhibition of the 5-HT reuptake transporter with selective 5-HT reuptake inhibitors (SSRIs) disrupted tight junctions and decreased milk protein mRNA expression in mouse, human, and bovine mammary cells. Selective 5-HT reuptake inhibitors act to increase the cellular exposure to 5-HT by preventing reuptake of 5-HT by the cell and eventual degradation. Increasing 5-HT concentration in milk via inhibiting its reuptake (SSRI), or by increasing the precursor for 5-HT synthesis 5-hydroxytryptophan, accelerated decline in milk synthesis at dry-off. We conclude that the 5-HT system in mammary tissue acts as a homeostatic regulator of lactation.

Effects of cortisol secreted via a 12-h infusion of adrenocorticotropic hormone on mineral homeostasis and bone metabolism in ovariectomized cows - Corrected Proof

D. Kim, N. Yamagishi, B. Devkota, K. Furuhama — 2012-05-17

Abstract: To evaluate the effects of endogenously secreted cortisol on mineral homeostasis and bone metabolism in cows, 4 ovariectomized Holstein cows were infused for 12 h with either an adrenocorticotropic hormone (ACTH) solution (0.5 mg/2 L isotonic NaCl solution per cow) or isotonic NaCl solution in a 2 × 2 crossover design. ACTH infusion stimulated cortisol secretion and increased plasma cortisol concentrations for 18 h (P < 0.001), leading to an elevated plasma glucose concentration until 36 h (P < 0.001). Plasma calcium and magnesium concentrations in ACTH-infused cows fluctuated within normal ranges, whereas hypophosphatemia was observed unequivocally. The biochemical bone resorption markers tartrate-resistant acid phosphatase 5b and hydroxyproline decreased following ACTH infusion (P < 0.001 and P = 0.003, respectively). Similarly, the bone formation marker, bone-specific alkaline phosphatase, decreased continuously until 72 h after the ACTH infusion (P < 0.001). These results demonstrate that increased secretion of cortisol via a 12-h ACTH infusion disrupted homeostasis of inorganic phosphate and suppressed bone metabolism in ovariectomized cows without involving gonadal steroid hormones.

A proteomic analysis of serum from dogs before and after a controlled weight-loss program - Corrected Proof

2012-05-17

Abstract: The objective of this study was to investigate how weight-loss program would alter the proteome of the serum of Beagle dogs. For this purpose, serum samples from 5 Beagle dogs, before and after weight loss, were analyzed using 2-dimensional electrophoresis. Protein profiles of all samples were obtained, divided into 2 classes (obese and lean), and compared using specific 2-dimensional software, giving a total of 144 spot matches. Statistical analysis revealed 3 spot matches whose expressions were modulated in response to weight loss: 2 protein spots were upregulated and 1 protein spot was downregulated in the obese state in comparison with the lean state of the dogs. Mass spectrometric identification of differentially regulated spots revealed that these protein spots corresponded to retinol-binding protein 4, clusterin precursor, and α-1 antitrypsin, respectively, which could be considered potential markers of obesity and obesity-related disease processes in dogs.

Reproductive seasonality in the mare: neuroendocrine basis and pharmacologic control - Corrected Proof

2012-05-14

Abstract: Reproductive seasonality in the mare is characterized by a marked decline in adenohypophyseal synthesis and secretion of LH beginning near the autumnal equinox. Thus, ovarian cycles have ceased in most mares by the time of the winter solstice. Endogenous reproductive rhythms in seasonal species are entrained or synchronized as a result of periodic environmental cues. In the horse, this cue is primarily day length. Hence, supplemental lighting schemes have been used managerially for decades to modify the annual timing of reproduction in the mare. Although a full characterization of the cellular and molecular bases of seasonal rhythms has not been realized in any species, many of their synaptic and humoral signaling pathways have been defined. In the mare, neuroendocrine-related studies have focused primarily on the roles of GnRH and interneuronal signaling pathways that subserve the GnRH system in the regulatory cascade. Recent studies have considered the role of a newly discovered neuropeptide, RF-related peptide 3 that could function to inhibit GnRH secretion or gonadotrope responsiveness. Although results that used native peptide sequences have been negative in the mare and mixed in all mammalian females, new studies that used an RFRP3 antagonist (RF9) in sheep are encouraging. Importantly, despite continuing deficits in some fundamental areas, the knowledge required to control seasonal anovulation pharmacologically has been available for >20 yr. Specifically, the continuous infusion of native GnRH is both reliable and efficient for accelerating reproductive transition and is uniquely applicable to the horse. However, its practical exploitation continues to await the development of a commercially acceptable delivery vehicle.

Expression of prostaglandin F2α (PGF2α) receptor and its isoforms in the bovine corpus luteum during the estrous cycle and PGF2α-induced luteolysis - Corrected Proof

2012-05-07

Abstract: Prostaglandin F2α (PGF2α) induces luteolysis via a specific receptor, PTGFR. Although PTGFR mRNA expression in the bovine corpus luteum (CL) has been studied previously, changes in PTGFR protein and its localization are not fully understood during the life span of the CL. In addition to full-length PTGFR, several types of PTGFR isoforms, such as PTGFRα (type I) and PTGFRζ (type II), were reported in the bovine CL, suggesting isoform-specific luteal action. Full-length PTGFR mRNA in the bovine CL increased from the early to the mid-luteal phase and decreased during luteolysis, whereas PTGFR protein remained stable. PTGFR protein was localized to both luteal and endothelial cells and was expressed similarly during the life span of the CL. Like full-length PTGFR mRNA, PTGFRα and PTGFRζ mRNA also increased from the early to mid-luteal phases, and mRNA of PTGFRζ, but not PTGFRα, decreased in the regressing CL. During PGF2α-induced luteolysis, the mRNAs of full-length PTGFR, PTGFR,α and PTGFRζ decreased rapidly (from 5 or 15 min after PGF2α injection), but PTGFR protein decreased only 12 h later. Silencing full-length PTGFR using small interfering RNA prevented PGF2α-stimulated cyclooxygenase-2 (PTGS2) mRNA induction. By contrast, PGF2α could stimulate vascular endothelial growth factor A (VEGFA) mRNA even when full-length PTGFR was knocked down, thus suggesting that PGF2α may stimulate PTGS2 via full-length PTGFR, whereas VEGFA is stimulated via other PTGFR isoforms. Collectively, PTGFR protein was expressed continually in the bovine CL during the estrous cycle, implying that PGF2α could function throughout this period. Additionally, the bovine CL expresses different PTGFR isoforms, and thus PGF2α may have different effects when acting via full-length PTGFR or via PTGFR isoforms.

Vascular and immune regulation of corpus luteum development, maintenance, and regression in the cow - Corrected Proof

K. Shirasuna, A. Nitta, J. Sineenard, T. Shimizu, H. Bollwein, A. Miyamoto — 2012-05-07

Abstract: The bovine corpus luteum (CL) is a unique, transient organ with well-coordinated mechanisms by which its development, maintenance, and regression are effectively controlled. Angiogenic factors, such as vascular endothelial growth factor A and basic fibroblast growth factor, play an essential role in promoting progesterone secretion, cell proliferation, and angiogenesis. These processes are critically regulated, through both angiogenic and immune systems, by the specific immune cells, including macrophages, eosinophils, and neutrophils, that are recruited into the developing CL. The bovine luteolytic cascade appears to be similar to that of general acute inflammation in terms of time-dependent infiltration by immune cells (neutrophils, macrophages, and T lymphocytes) and drastic changes in vascular tonus and blood flow, which are regulated by luteal nitric oxide and the vasoconstrictive factors endothelin-1 and angiotensin II. Over the period of maternal recognition of pregnancy, the maternal immune system should be well controlled to accept the semiallograft fetus. The information on the presence of the developing embryo in the genital tract is suggested to be transmitted to the ovary by both the endocrine system and the circulating immune cells. In the bovine CL, the lymphatic system, but not the blood vascular system, is reconstituted during early pregnancy, and interferon tau from the embryo could trigger this novel phenomenon. Collectively, the angiogenic and vasoactive factors produced by luteal cells and the time-dependently recruited immune cells within the CL and their interactions appear to play critical roles in regulating luteal functions throughout the life span of the CL.

Expression of genes for interleukins, neuropeptides, growth hormone receptor, and leptin receptor in adipose tissue from growing broiler chickens - Corrected Proof

G.J. Hausman, C.R. Barb, B.D. Fairchild, J. Gamble, L. Lee-Rutherford — 2012-05-07

Abstract: In this study, total RNA was collected from abdominal adipose tissue samples obtained from 10 broiler chickens at 3, 4, 5, and 6 wk of age and prepared for quantitative real-time PCR analysis. Quantitative real-time PCR analysis was used to examine the influence of age on the expression of the adipose tissue genes for IL-1β, −6, −10, −15, −18; brain-derived neurotropic factor; ciliary neurotropic factor; interferon γ, neuropeptide Y receptor Y1; neuropeptide Y; nucleobindin 2; growth hormone receptor; leptin receptor; and visfatin. Between 3 and 6 wk of age, leptin receptor expression decreased (P = 0.013) with age, whereas expression of IL-15 (P = 0.015) and growth hormone receptor (P = 0.002) increased. Furthermore, IL-18 (P < 0.001) and visfatin (P = 0.007) expression increased between 4 and 6 wk of age. This is a unique exhibition of age-related changes in cytokine gene expression in chicken adipose tissue. Future studies are needed to elucidate the role of adipose tissue cytokines in growth and, possibly, disease resistance.

Effects of melatonin on islet neogenesis and beta cell apoptosis in streptozotocin-induced diabetic rats: an immunohistochemical study - Corrected Proof

N. Simsek, M. Kaya, A. Kara, I. Can, A. Karadeniz, Y. Kalkan — 2012-04-27

Abstract: This investigation was carried out to explore the antidiabetic, antiapoptotic and neogenetic effects of melatonin (MLT) in streptozotocin-induced diabetic rats. Sixty-four male rats were assigned randomly to one of four groups for periods of 21 and 42 d as follows; i) control, ii) MLT, iii) diabetic (DM), and iv) DM + MLT. Immunohistochemical methods were used -with pancreatic tissue to determine the intensity of insulin, caspase-3 and Bcl-xL immune reactivities, and new islet formation. In untreated DM rats, BW loss, increased plasma glucose and MLT concentrations, as well as cytoplasmic degranulation and vacuolization were observed. We also observed a marked increase in the number of apoptotic caspase-3 positive cells and a few insulin- positive cells, but not antiapoptotic Bcl-xL positive cells. Observations in the DM + MLT-treated group revealed a high intensity of insulin- and antiapoptotic Bcl-xL immune reactivities at 21 and 42 d. Moreover, data indicated that MLT may cause beta cell proliferation and that new small islets originate from cells associated with ductal epithelium and from centroacinar cells by day 21. These data indicate that; i) MLT treatment may stimulate neogenesis in the pancreas of diabetic rats, and ii) MLT's antiapoptotic action may increase beta cell differentiation and caspase-3 inactivation or Bcl-xL activation.

Effects of tryptophan supplementation on cashmere fiber characteristics, serum tryptophan, and related hormone concentrations in cashmere goats - Corrected Proof

H. Ma, W. Zhang, W.H. Song, P. Sun, Z.H. Jia — 2012-04-27

Abstract: This study was designed to investigate the effects of tryptophan (Trp) supplementation on cashmere fiber characteristics and on serum Trp, melatonin (MEL), prolactin (PRL), insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), and thyroxine (T4) concentrations in cashmere goats during the cashmere fast-growth period. Thirty-six Liaoning cashmere wether goats were stratified on the basis of body weight (28 ± 0.8 kg) and assigned randomly to 1 of the following 4 rumen-protected Trp treatments: 0, 2.0, 4.0, and 6.0 g per goat per day. The experimental period lasted 137 d. Blood samples were collected monthly during the daytime (8:00 AM) and at night (8:00 PM). Tryptophan supplementation improved cashmere growth rates, cashmere weight, and body weight (P = 0.001) and increased serum Trp levels, nighttime MEL concentrations, IGF-1, and T3 and T4 concentrations (P < 0.05). Across the treatments and sampling months, a highly positive correlation between cashmere growth rate and nighttime serum MEL concentrations was observed (r = 0.879, P = 0.001). A moderately negative correlation between cashmere growth rates and serum PRL concentrations during the day and at night (rday = –0.645, P = 0.007; rnight = –0.583, P = 0.018) was observed. A moderately positive correlation between the cashmere growth rate and the daytime serum IGF-1 concentration (r = 0.536, P = 0.032) was observed, and no correlation was found between the cashmere growth rate and the other serum hormone concentrations. These data indicate that changes in serum concentrations of MEL, IGF-1, and PRL are related to cashmere growth in Liaoning cashmere goats during the cashmere fast-growth period. Under the experimental conditions of the current trial, we suggest that Trp may promote cashmere growth by increasing daytime IGF-1 and nighttime MEL secretion.

Kisspeptins and the reproductive axis: potential applications to manage reproduction in farm animals - Corrected Proof

A. Caraty, C. Decourt, C. Briant, M. Beltramo — 2012-04-26

Abstract: Kisspeptins (Kp) are a family of neuropeptides produced mainly by two hypothalamic neuronal cell populations. They have recently emerged as a major regulator of the gonadotropin axis and their action is located upstream of the gonadotropin-releasing hormone (GnRH) cell population. In less than 10 yr a growing body of literature has demonstrated the involvement of these peptides in most, if not all, aspects of reproductive axis maturation and function. In contrast to these abundant basic research studies, few experiments have evaluated the potential application of Kp as tools to manipulate reproduction in domestic animals. In mammals, exogenous Kp administration potently stimulates gonadotropin secretion. This action is exerted mainly, if not exclusively, through the stimulation of GnRH release. Intravenous, intraperitoneal, or subcutaneous administration of Kp induced a robust and rapid increase in plasma gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]). However, this stimulatory effect is of short duration. Prolonged LH and FSH release over several hours can be achieved only when Kp are given as repeated multiple bolus or as an infusion. Kp administration was used in two experimental models, ewe and pony mare, with the aim of inducing well-timed and synchronized ovulations. During the breeding season, progesterone-synchronized ewes were given an intravenous infusion of Kp starting 30 h after the removal of progesterone implants. An LH surge was induced in all Kp-treated animals within 2 h of infusion onset. In contrast, in pony mares a constant infusion of Kp for 3 d in the the late follicular phase was unable to induce synchronized ovulation. Another set of studies showed that Kp could be used to activate reproductive function in acyclic animals. Pulsatile administration of Kp in prepubertal ewe lambs was shown to activate ovarian function, leading to enhanced ovarian steroidogenesis, stimulation of LH preovulatory surge, and ovulation. In anestrous ewes, an intravenous infusion of a low dose of Kp induced an immediate and sustained release of gonadotropins, followed a few hours later by an LH surge. This hormonal pattern mimicked hormonal changes normally observed during the estrous cycle follicular phase and was associated with a high percentage of ovulating animals (80%). In summary, exogenous administration of Kp appears to be a new tool to manipulate reproduction. However, optimal doses and periods of treatment should be defined for each species, and the development of powerful analogs or long-term release formulations is necessary before large-scale applications in domestic animals could be envisaged.

Sociosexual stimuli and gonadotropin-releasing hormone/luteinizing hormone secretion in sheep and goats - Corrected Proof

P.A.R. Hawken, G.B. Martin — 2012-04-26

Abstract: Sociosexual stimuli have a profound effect on the physiology of all species. Sheep and goats provide an ideal model to study the impact of sociosexual stimuli on the hypothalamic-pituitary-gonadal axis because we can use the robust changes in the pulsatile secretion of luteinizing hormone as a bioassay of gonadotropin-releasing hormone secretion. We can also correlate these changes with neural activity using the immediate early gene c-fos and in real time using changes in electrical activity in the mediobasal hypothalamus of female goats. In this review, we will update our current understanding of the proven and potential mechanisms and mode of action of the male effect in sheep and goats and then briefly compare our understanding of sociosexual stimuli in ungulate species with the “traditional” definition of a pheromone.

The effect of combination treatment with trenbolone acetate and estradiol-17β on skeletal muscle expression and plasma concentrations of oxytocin in sheep - Corrected Proof

K. Kongsuwan, M.R. Knox, P.G. Allingham, R. Pearson, B.P. Dalrymple — 2012-04-16

Abstract: Implantation of trenbolone acetate (TBA) in conjunction with estradiol-17β (E2) increases growth, feed conversion efficiency, and carcass leanness in cattle. Our previous study in Brahman steers suggested that the neuropeptide hormone oxytocin (OXT) may be involved in increasing muscle growth after TBA-E2 treatment. The present study aimed to determine whether OXT mRNA expression in the longissimus muscle (LM) is also up-regulated in TBA-E2-implanted wethers as has been found in steers. Real-time quantitative PCR was used to measure the expression of the gene encoding the OXT precursor, three genes with increased expression in the LM muscle of TBA-E2-treated steers, MYOD1 (muscle transcription factor), GREB1 (growth regulation by estrogen in breast cancer 1), and WISP2 (Wnt-1 inducible signaling pathway protein 2), and two genes encoding IGF pathway proteins, IGF1, IGFR, in the LM of both untreated and TBA-E2-treated wethers. The expression of OXT mRNA in wethers that received the TBA-E2 treatment was increased ∼4.4-fold (P = 0.01). TBA-E2 treatment also induced a 2.3-fold increase in circulating OXT (P = 0.001). These data, together with the observation that untreated wethers had much higher baseline concentrations of circulating OXT than previously observed in steers, suggest that wethers and steers have quite different OXT hormone systems. TBA-E2 treatment had no effect on the expression of IGF1, IGFR, and the muscle regulatory gene MYOD1 mRNA levels in wethers (P ≥ 0.15), but there was an increase in the expression of the two growth-related genes, GREB1 (P = 0.001) and WISP2 (P = 0.04). Both genes are common gene targets for both the estrogen and androgen signaling pathways. Consequently, their actions may contribute to the positive interaction between TBA and E2 on additive improvements on muscle growth.

Administration of botanicals with the diet regulates gene expression in peripheral blood cells of Sarda sheep during ACTH challenge - Corrected Proof

S. Sgorlon, M. Colitti, E. Asquini, A. Ferrarini, A. Pallavicini, B. Stefanon — 2012-04-16

Abstract: The aim of the present research was to investigate the regulation of gene expression in ovine blood leukocytes during ACTH-induced cortisol release and the effect of dietary administration of botanicals to counteract the evoked response in polymorphonucleate cells (PMNCs). Thirty-six homogeneous Sarda sheep (age, 18 ± 4.1 mo; BW, 38.7 ± 1.3 kg) were allotted to six groups of six sheep each. One group was used as a negative control (Saline) and five groups were treated, every 12 h for 48 h, with 0.5 mL of ACTH agonist (250 μg/mL of tetracosactrin). Before ACTH treatment, four of the five ACTH-treated groups were separated and fed for 22 d with a basal diet supplemented with extracts from Echinacea angustifolia roots (PO + ACTH), Echinacea angustifolia flowers (EA + ACTH), Andrographis paniculata (AP + ACTH), and the bark of Larix decidua milled (LB + ACTH). Control groups (Saline and ACTH) were fed with the same basal diet without botanicals. Total RNA was extracted from blood samples collected before (T0) and after 3 h (T3) and 51 h (T51) from the first ACTH injection, and transcriptome analysis was performed using a custom oligoarray, designed from 12,194 Ovis aries UniGenes on a CombiMatrix platform. At T3, treatment with ACTH caused down-regulation of transcripts (P < 0.001) involved in “response to stress” (GADD45A, GADD45B, WRNIP1, and XRCC6) and in “innate immune response” (MAPK3 and NFkBIB). At T51, treatment with ACTH caused down-regulation (P < 0.001) of genes involved in “immune response” (IFNG and IL2) and up-regulation (P < 0.001) of NF-κB1 and TP53. Each botanical produced a different (P < 0.001) molecular signature for these genes at T3 and T51. The most active botanical in modulating transcriptome modifications in PMNCs after ACTH-induced cortisol release was Larix decidua Mill bark followed by Polinacea roots. These botanicals can be viewed as promising feed supplements in ruminants to cope with conditions associated with increased concentrations of plasma cortisol.

Effect of luteinizing hormone on the right regressing ovary of newly hatched chicks treated during embryonic development - Corrected Proof

M.G. González-Morán, A. Guzmán — 2012-04-05

Abstract: We studied the histologic and stereological changes induced in the right ovary of newly hatched chicks treated with LH during their embryonic development. Results indicate that LH administration causes a diminution in size and total volume (P < 0.01) of the right ovary, as well as a decrease in the total volume of lacunar channels, blood vessels, and interstitium. Other changes obtained after LH treatment were a reduction (P < 0.001) in the number of germ cells, as well as an increase in the total volume of interstitial cell cords (P < 0.01). This expansion is due to the increase of cellular volume of interstitial cells (P < 0.001) and not to their number, which decrease in the LH-treated right ovary. All these modifications were similar to those occurring in the regressing right ovary during development. The findings suggest that the right ovary of the newly hatched chick is able to respond to LH treatment during embryonic development, inducing marked histologic changes that accelerate its regression.

Energy metabolism in the newborn farm animal with emphasis on the calf: endocrine changes and responses to milk-born and systemic hormones - Corrected Proof

H.M. Hammon, J. Steinhoff-Wagner, U. Schönhusen, C.C. Metges, J.W. Blum — 2012-04-05

Abstract: Neonatal mammals need adaption to changes in nutrient supply because energy intake shifts from continuous parenteral supply of nutrients (mainly glucose, lactate, and amino acids) via the placenta to discontinuous colostrum and milk intake with lactose and fat as main energy sources. Besides ingested lactose, endogenous glucose production is essential in the neonate to assure sufficient glucose availability. Fetal endogenous glucose production is low, but endocrine changes (especially the prenatal rise of glucocorticoid production) promote maturation of metabolic pathways that enable marked glycogen synthesis before and enhanced gluconeogenesis after birth to establish an adequate glucose status during postnatal maturation. In preterm born farm animals gluconeogenic activity is low, mainly because of a low glucocorticoid and thyroid status. In full-term neonates, endogenous glucose production increases with age. Colostral bioactive components (such as growth factors, hormones, bioactive peptides, and cytokines) do not have a direct effect on endogenous glucose production. However, colostrum feeding stimulates intestinal growth and development, an effect at least in part mediated by bioactive substances. Increased nutrient and glucose absorption thus allows increased glucose supply and hepatic glycogen storage, which improves the glucose status. The improved energetic status of colostrum-fed neonates is reflected by an accelerated maturation of the somatotropic axis, leading especially to enhanced production of IGF-I in the neonate. Secretion and production of hormones involved in the regulation of glucose and fat metabolism in neonates depend on the developmental stage and the response to feeding. In addition, many such hormones have actions in the neonate that differ from adult animals. Endocrine action to support endogenous energy supply in neonates is probably not fully established, and therefore, needs postnatal maturation. Therefore, our knowledge on energy metabolism in the neonate needs to be extended to better understand the function and the failure and to assess endocrine responses during the neonatal period.

Influence of environmental temperature on the physiological, endocrine, and immune responses in livestock exposed to a provocative immune challenge - Corrected Proof

J.A. Carroll, N.C. Burdick, C.C. Chase, S.W. Coleman, D.E. Spiers — 2012-03-19

Abstract: Although livestock experience many stressors throughout their life, one of the most commonly experienced, and most difficult to control, is stress caused by fluctuations in environmental temperatures that extend beyond the thermoneutral (TN) zone for an animal. In swine, cold stress has long been recognized as a main cause of neonatal morbidity and mortality. A possible explanation for this increased morbidity and mortality may be related to their inability to generate a febrile response. Previously, we reported that the acute phase immune response, including the generation of fever, after exposure to lipopolysaccharide (LPS; Escherichia coli O111: B4; Sigma-Aldrich, St Louis, MO, USA) is substantially altered in neonatal pigs maintained in a cold environment (ie, 18°C). Neonatal pigs that were maintained in a cold environment and administered LPS experienced a period of hypothermia coupled with altered endocrine and proinflammatory cytokine responses that could prove detrimental. In cattle, we previously reported differences in the acute phase immune response of two diverse breeds of Bos taurus cattle (Angus and Romosinuano) when maintained under TN conditions and exposed to LPS. More recently we have reported that differences in the stress and immune responses of Angus and Romosinuano heifers varies, depending on whether the cattle were housed at either TN or heat stress air temperatures. Our data clearly show that even intermittent periods of heat stress similar to that experienced in production environments can have significant effects on the stress and innate immune responses of cattle. Understanding the effect of thermal stress on livestock is critical to developing and implementing alternative management practices to improve their overall health and well-being.

Porcine somatotropin alters insulin response in growing pigs by reducing insulin sensitivity rather than changing responsiveness - Corrected Proof

D. Wray-Cahen, F.R. Dunshea, R.D. Boyd, A.W. Bell, D.E. Bauman — 2012-03-19

Abstract: Exogenous porcine somatotropin (pST) treatment consistently improves growth performance and reduces fat deposition in pigs, and it is hypothesized that one component of the mechanism is through altering the sensitivity and/or responsiveness to insulin. Therefore, a study was conducted to investigate the effect of pST treatment on whole-body glucose metabolism in response to varying doses of insulin. Eight barrows were surgically prepared with indwelling catheters and randomly assigned to one of two treatment groups (0 or 120 μg pST/kg BW · d) for 13 d. Whole-body glucose kinetics were measured during infusion of [6-3H]-glucose under basal conditions and during hyperinsulinemic-euglycemic clamps at various insulin infusion rates (7, 28, and 140, and 14, 70, and 280 ng insulin/kg BW · min) and alterations in the dose–response parameters were calculated with nonlinear regression. Treatment with pST increased basal plasma concentrations of glucose (36%; P = 0.005), insulin (276%; P = 0.001), and NEFAs (177%; P = 0.01) and decreased the rate of glucose disappearance (−59%; P = 0.001). The responsiveness (maximum response) for steady state glucose infusion rate to maintain glycemia was not altered by pST (112 vs 106 μmol/min · kg; P = 0.78), whereas the sensitivity (effective dose at 50% of maximum response) was increased almost 7-fold (1.3 vs 8.7 ng/mL; P = 0.027). Similar responses were observed for rate of glucose disappearance and insulin-dependent glucose utilization. Therefore, pST-induced insulin resistance with regard to whole-body glucose uptake is due to a reduced sensitivity to insulin, rather than a change in responsiveness.

Characterization of glucagon-like peptide 1 receptor (GLP1R) gene in chickens: functional analysis, tissue distribution, and identification of its transcript variants - Corrected Proof

G. Huang, J. Li, H. Fu, Z. Yan, G. Bu, X. He, Y. Wang — 2012-03-15

Abstract: Glucagon-like peptide 1 (GLP1) receptor plays a critical role in mediating the biological actions of GLP1 in mammals and fish; however, the gene structure, expression, and functionality of GLP1 receptor (GLP1R) remain largely unknown in birds. In this study, the full-length cDNA of chicken GLP1R (cGLP1R) was first cloned from brain tissue by reverse transcription PCR. The putative cGLP1R is 459 amino acids in length and shares high amino acid sequence identity with that of human (79%), rat (80%), and Xenopus (75%). Using a pGL3-CRE luciferase reporter system, we found that cGLP1R expressed in Chinese hamster ovary cells could be potently activated by cGLP1 (EC50, 0.11 nM) but not by other structurally related peptides, indicating that cGLP1R is a functional receptor specific to cGLP1. Interestingly, in addition to identification of the transcript encoding cGLP1R of 459 amino acids, eight transcript variants, which were generated by alternative mRNA splicing and predicted to encode either C-terminally or N-terminally truncated cGLP1Rs, were also identified from chicken brain or testis. In line with this finding, multiple cGLP1R transcripts were detected to be expressed in most chicken tissues examined, including pancreas, gastrointestinal tract, and various brain regions by reverse transcription PCR. Using the dual-luciferase reporter assay system, we further found that the 5′-flanking region of cGLP1R gene displays promoter activities in cultured HepG2 and HEK293 cells, suggesting that it may control cGLP1R gene transcription in chicken tissues, including nonpancreatic tissues. Taken together, the results from the present study establish a molecular basis to investigate the roles of GLP1 in chickens.

In ovo leptin administration inhibits chorioallantoic membrane angiogenesis in female chicken embryos through the STAT3-mediated vascular endothelial growth factor (VEGF) pathway - Corrected Proof

L. Su, K. Rao, F. Guo, X. Li, A.A. Ahmed, Y. Ni, R. Grossmann, R. Zhao — 2012-03-15

Abstract: Previous studies indicate that leptin regulates placental angiogenesis and fetal growth in mammals and that in ovo leptin administration affects embryonic development and hatch weight in the chicken. To test the hypothesis that leptin affects embryonic growth through modifying chorioallantoic membrane (CAM) angiogenesis, we injected 0.5 μg of recombinant murine leptin into the albumen of fertilized eggs before incubation. On embryonic day 12 (E12), the number and the total area of blood vessels on CAM were measured, and expression of genes involved in angiogenesis was quantitated to show the possible mechanisms. Leptin in ovo administration decreased (P < 0.05) both the total area of blood vessels and the number of small-sized capillaries on CAM of E12 female chicken embryos, which coincided with significantly decreased (P < 0.05) embryo weight on E12 and BW at hatching. Vascular endothelial growth factor (VEGF) and inducible and endothelial nitric oxide synthases (iNOS and eNOS) were all downregulated (P < 0.05) in CAM both at the mRNA and protein/activity levels with reduced (P < 0.05) nitric oxide (NO) concentration in chorioallantoic fluid of female embryos. Furthermore, signal transducer and activator of transcription-3 (STAT3) was found to be diminished (P < 0.05) both at the mRNA and protein levels and associated with decreased (P < 0.05) binding of STAT3 to VEGF promotor in the CAM of leptin-treated E12 female embryos. These data suggest that in ovo leptin administration affects CAM angiogenesis and embryo growth in female chicken embryos, probably through STAT3-mediated VEGF/NO pathways.

Novel diabetes mellitus treatment: mature canine insulin production by canine striated muscle through gene therapy - Corrected Proof

2012-03-14

Abstract: Muscle-targeted gene therapy using insulin genes has the potential to provide an inexpensive, low maintenance alternative or adjunctive treatment method for canine diabetes mellitus. A canine skeletal muscle cell line was established through primary culture, as well as through transdifferentiation of canine fibroblasts after infection with a myo-differentiation gene containing adenovirus vector. A novel mutant furin-cleavable canine preproinsulin gene insert (cppI4) was designed and created through de novo gene synthesis. Various cell lines, including the generated canine muscle cell line, were transfected with nonviral plasmids containing cppI4. Insulin and desmin immunostaining were used to prove insulin production by muscle cells and specific canine insulin ELISA to prove mature insulin secretion into the medium. The canine myoblast cultures proved positive on desmin immunostaining. All cells tolerated transfection with cppI4-containing plasmid, and double immunostaining for insulin and desmin proved present in the canine cells. Canine insulin ELISA assessment of medium of cppI4-transfected murine myoblasts and canine myoblast and fibroblast mixture proved presence of mature fully processed canine insulin, 24 and 48 h after transfection. The present study provides proof of principle that canine muscle cells can be induced to produce and secrete canine insulin on transfection with nonviral plasmid DNA containing a novel mutant canine preproinsulin gene that produces furin-cleavable canine preproinsulin. This technology could be developed to provide an alternative canine diabetes mellitus treatment option or to provide a constant source for background insulin, as well as C-peptide, alongside current treatment options.

New developments on the galactopoietic role of prolactin in dairy ruminants - Corrected Proof

P. Lacasse, V. Lollivier, F. Dessauge, R.M. Bruckmaier, S. Ollier, M. Boutinaud — 2012-01-27

Abstract: In most mammals, prolactin (PRL) is essential for maintaining lactation and its suppression strongly inhibits lactation. However, the involvement of PRL in the control of ruminant lactation is less clear because inconsistent effects on milk yield have been observed with short-term suppression of PRL by bromocriptine. By contrast, in vitro studies have provided evidence that PRL helps to maintain the differentiation state and act as a survival factor for mammary epithelial cells. Therefore, a series of experiments were conducted to assess the galactopoietic role of PRL. In a first experiment, daily injections of the PRL inhibitor quinagolide reduced milking-induced PRL release and induced a faster decline in milk production. Milk production was correlated with PRL released at milking. Quinagolide reduced mammary cell activity, survival, and proliferation. During the last week of treatments, differential milking (1× vs 2×) was applied. The inhibition of milk production by quinagolide was maintained in the udder half that was milked 2× but not in the udder half milked 1×, suggesting that the response to PRL is modulated at the gland level. In a second experiment, cows were injected with quinagolide, quinagolide + injection of bovine PRL at milking time, or water. As in the first experiment, quinagolide reduced milk, protein, and lactose yields. Although PRL injections at milking time were not sufficient to restore milk yield, they tended to increase milk protein and lactose yields and increased the viability of milk-purified mammary epithelial cells. Recently, we investigated the use of quinagolide at drying off. Treating late-lactation cows with quinagolide decreased milk production within the first day of treatment and induced faster increases in somatic cells and bovine serum albumin content in mammary secretions after drying off, which indicates an acceleration of mammary gland involution. In conclusion, these data, combined with data from other studies, provide a good body of evidence indicating that PRL is galactopoietic in dairy cows. However, the response to PRL appears to be modulated at the mammary gland level.

The role of kisspeptin and gonadotropin inhibitory hormone in the seasonal regulation of reproduction in sheep - Corrected Proof

J.T. Smith — 2011-12-19

Abstract: Sheep are seasonal breeders, experiencing an annual period of reproductive quiescence in response to increased photoperiod during the late-winter into spring and renaissance during the late summer. The nonbreeding (anestrous) season is characterized by a reduction in the pulsatile secretion of GnRH from the brain, in part because of an increase in negative feedback activity of estrogen. Neuronal populations in the hypothalamus that produce kisspeptin and gonadotropin-inhibitory hormone (GnIH) appear to be important for the seasonal shift in reproductive activity, and the former are also mandatory for puberty onset. Kisspeptin cells in the arcuate nucleus (ARC) and preoptic area appear to regulate GnRH neurons and transmit sex-steroid feedback signals to these neurons. Moreover, kisspeptin expression in the ARC is markedly up-regulated at the onset of the breeding season, as too are the number of kisspeptin fibers in close apposition to GnRH neurons. The lower levels of kisspeptin seen during the nonbreeding season can be “corrected” by infusion of kisspeptin, which causes ovulation in seasonally acyclic females. The role of GnIH is less clear, but mounting evidence supports a role for this neuropeptide in the inhibitory regulation of both GnRH secretion and gonadotropin release from the pituitary gland. Contrary to kisspeptin, GnIH expression is markedly reduced at the onset of the breeding season. In addition, the number of GnIH fibers in close apposition to GnRH neurons also decreases during this time. Importantly, exogenous GnIH treatment can block both the pulsatile release of LH and the preovulatory LH surge during the breeding season. In summary, it is most likely the integrated function of both these neuropeptide systems that modulate the annual shift in photoperiod to a physiological change in fertility.

Quantification of the GH/IGF-axis components: Lessons from human studies - Corrected Proof

J. Frystyk — 2011-12-07

Abstract: Originally, the circulating bioactivity of IGF-I was estimated by bioassays measuring the ability of serum to stimulate uptake of labeled sulfate or thymidine in cultures of costal cartilage or by the ability of serum to stimulate the uptake of glucose in fat tissue cultures. However, because of their laborious and unspecific nature, the original bioassays were quickly abandoned with the development of the first RIA for IGF-I in 1977. Consequently, for the past three decades the endogenous IGF-I bioactivity has been almost exclusively estimated by the use of immunoassays. Beyond any doubt, the immunoassays have provided an extensive insight into IGF-I physiology and pathophysiology. However, immunoassays ignore the presence of the IGFBPs, which are important regulators of IGF-I action in vivo. In addition, immunoassays do not consider the presence of IGF-II, which also interacts with the IGF-I receptor (IGF-IR). This aroused our interest to reintroduce the bioassay; therefore, we established a cell-based kinase receptor activation (KIRA) assay based on cells transfected with the human IGF-IR. The output signal of the KIRA assay is IGF-IR phosphorylation, and, as such, it is highly specific. Further, because detection of phosphorylated IGF-IRs is based on modern immunoassay techniques, the overall performance of the assay is close to that of a traditional IGF-I immunoassay. The first part of this review comprises a short description of the bioassay, and a more in-depth presentation of the data that have been obtained so far. It will be demonstrated that the bioassay is indeed able to yield novel information on the IGF system, most likely because it is able to integrate the different components of the IGF system into one signal: IGF-IR activation. As IGF-I, circulating GH is bound to larger proteins, the far most important GH-binding protein (GHBP) is identical to the extracellular domain of the GH receptor (GHR). Because of its origin, GHBP binds GH with the same affinity as GHR and, consequently, GHBP may affect GH bioactivity as well as pharmacokinetics. To improve our knowledge on the complex interaction between GH and GHBP in vivo, we found it of interest to develop a method for determination of free GH. To this end, we developed an ultrafiltration assay that enabled isolation of free GH in undiluted serum during approached in vivo–like conditions. The last part of this review presents our current data on free GH and its interaction with GHBP.