Luteolysis in the cow: a novel concept of vasoactive molecules

Ano: 2009 | Volume: 6 | Número: 1

Autores: A. Miyamoto, K. Shirasuna

Palavras-chave: endothelin-1, luteal blood flow, luteolysis, nitric oxide, prostaglandin f2?

Resumo Inglês:

The corpus luteum (CL) undergoes drastic
changes in its function and structure during the estrous
cycle. To secrete a sufficient amount of progesterone
(P4) to ensure the occurrence of pregnancy in a cow
with a body weight greater than 500 kg, the bovine CL
weighs 5-8 g which is 2-3 thousand times heavier than
rat CL. If pregnancy does not occur successfully, rapid
luteolysis is caused by prostaglandin F2α (PGF2α) that is
released from the endometrium around days 17-19 of
the estrous cycle in the cow. Thus, it is clear that the
bovine CL lifespan is controlled by well-coordinated
mechanisms. As the CL matures, the steroidogenic cells
establish contact with many capillary vessels, so that the
CL is composed of a large number of vascular
endothelial cells that can account for up to 50% of all
cells in the bovine CL. Also, luteal endothelial cells
secrete several vasoactive substances such as PGF2α,
nitric oxide, endothelin-1 and angiotensin II that
regulate blood flow as well as P4 secretion in an
autocrine/paracrine manner within the CL. Therefore,
blood vessels and endothelial cells within the CL have
an essential role in luteal function in the cow,
suggesting that the study of vasoactive molecules from
the CL is of great importance to give an insight into
systems which regulate luteolysis locally. In the present
review, we describe novel concepts on the luteolytic
mechanisms in the cow, with emphasis on luteal blood
flow and vasoactive molecules.