A cooperative action of endothelin-1 with prostaglandin F2α on luteal function in the cow

Shirasuna, K.; Watanabe, S.; Oki, N.; Wijayagunawardane, M.P.B.; Matsui, M.; Ohtani, M.; Miyamoto, A.

doi:10.1016/j.domaniend.2005.10.004

« Previous Next »Domestic Animal Endocrinology
Volume 31, Issue 2 , Pages 186-196, August 2006

A cooperative action of endothelin-1 with prostaglandin F_2α on luteal function in the cow

K. Shirasuna
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
S. Watanabe
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
N. Oki
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
M.P.B. Wijayagunawardane
- Department of Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka
M. Matsui
- Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
M. Ohtani
- The Field Center of Animal Science & Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
A. Miyamoto
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
- Corresponding author. Tel.: +81 155 49 5416; fax: +81 155 49 5593.

Received 19 July 2005; received in revised form 11 October 2005; accepted 14 October 2005. published online 21 November 2005.

Abstract

Prostaglandin F_2α (PGF_2α) is the primary luteolysin in the cow, and luteal endothelin-1 (ET-1) interacts with PGF_2α during the process of luteolysis. In contrast, a developing corpus luteum (CL) is refractory to exogenous administration of PGF_2α. Thus, the present study was aimed to investigate the functional relationship between ET-1 and PGF_2α in the mid-CL (PGF_2α-sensitive) and early-CL (PGF_2α-refractory). In the mid-CL model, cows (n=6/treatment) were assigned to receive one of five types of treatments on day 10 of the estrous cycle: (1) an injection of saline; control, (2) a 500μg of PGF_2α analogue (sufficient dose to induce luteolytis); full-PG, (3) an intraluteal injection of 0.25mg ET-1; ET-1, (4) a 125μg of PGF_2α (insufficient dose to induce luteolytis); 1/4PG or (5) an intraluteal injection of 0.25mg ET-1 after administration of a insufficient dose of PGF_2α analogue; 1/4PG/ET. In the early-CL model, cows were assigned to receive one of two types of treatments on day 5 of the estrous cycle: (1) a sufficient dose of PGF_2α analogue; PG (n=5) or (2) an intraluteal injection ET-1 after a sufficient dose of PGF_2α; PG/ET (n=7). In the mid-CL model, 1/4PG/ET resulted in a rapid reduction of progesterone (P) concentrations similar to that in full-PG from the next day. However, the levels of P in 1/4PG/ET (1.5–2.5ng/ml) kept significantly higher than that in full-PG (<0.5ng/ml). ET-1 or 1/4PG did not decrease plasma P concentrations (4–6ng/ml). The plasma ET-1 levels increased with the full-PG administration. In the early-CL model, both treatments had no effect on plasma P increase and ET-1 levels. The overall results indicate that the intraluteal ET-1 injection after administration of insufficient dose of PGF_2α induces the depression of P secretion in vivo during the mid luteal phase in the cow, supporting the concept that ET-1 is one of a local mediator of functional luteolysis in the cow. The result further indicates that the early-CL is not only PG-refractory but also ET-1-refractory.