Prostaglandin F_2α increases endothelial nitric oxide synthase in the periphery of the bovine corpus luteum: the possible regulation of blood flow at an early stage of luteolysis

Authors

Koumei Shirasuna, Obihiro University of Agriculture and Veterinary Medicine
Sho Watanabe, Obihiro University of Agriculture and Veterinary Medicine
Takayuki Asahi, Obihiro University of Agriculture and Veterinary Medicine
Missaka P. B. Wijayagunawardane, University of Peradeniya
Kiemi Sasahara, Obihiro University of Agriculture and Veterinary Medicine
Chao Jiang, University Nebraska Medical Center
Motozumi Matsui, Obihiro University of Agriculture and Veterinary Medicine
Motoki Sasaki, Obihiro University of Agriculture and Veterinary Medicine
Takashi Shimizu, Obihiro University of Agriculture and Veterinary Medicine
John S. Davis, University of Nebraska Medical CenterFollow
Akio Miyamoto, Obihiro University of Agriculture and Veterinary MedicineFollow

Date of this Version

2008

Comments

Published in Reproduction (2008) 135 527–539; DOI: 10.1530/REP-07-0496

Abstract

Prostaglandin F_2α (PGF_2α) released from the uterus causes alterations in luteal blood flow, reduces progesterone secretion, and induces luteolysis in the bovine corpus luteum (CL).We have recently discovered that luteal blood flow in the periphery of the mature CL acutely increases coincidently with pulsatile increases in a metabolite of PGF_2α (PGFM). In this study, we characterized changes in regional luteal blood flow together with regional alterations in endothelial nitric oxide synthase (eNOS) expression during spontaneous luteolysis and in response to PGF_2α. Smooth muscle actin-positive blood vessels larger than 20 μm were observed mainly in the periphery of mature CL. PGF_2α receptorwas localized to luteal cells and large blood vessels in the periphery of mid-CL. PGF2a acutely stimulated eNOS expression in the periphery but not in the center of mature CL. Injection of the NO donor S-nitroso-N-acetylpenicillamine into CL induced an acute increase in luteal blood flow and shortened the estrous cycle. In contrast, injection of the NOS inhibitor _L-NAME into CL completely suppressed the acute increase in luteal blood flow induced by PGF_2α and delayed the onset of luteolysis. In conclusion, PGF_2α has a siterestricted action depending on not only luteal phase but also the region in the CL. PGF_2α stimulates eNOS expression, vasodilation of blood vessels, and increased luteal blood flow in periphery of mature CL. Furthermore, the increased blood flow is mediated by NO, suggesting that the acute increase in peripheral blood flow to CL is one of the first physiological indicators of NO action in response to PGF_2α.