Nitric Oxide and Luteal Blood Flow in the Luteolytic Cascade in the Cow

The corpus luteum (CL) of the estrous cycle in the cow is a dynamic organ which has a lifespan of approximately 17-18 days. The main function of the CL is to produce progesterone (P) that requires for achievement and maintenance of pregnancy. If pregnancy does not occur successfully, the CL must regress within a few days to induce the next chance of ovulation. As the CL matures, the steroidogenic cells establish contact with many capillary vessels, consequently the CL is composed of a large number of vascular endothelial cells that can account for up to 50% of all cells. Therefore, blood vessels and blood flow within the CL have an essential role in luteal function. Nitric oxide (NO), a strong vasorelaxant, is now known to play key roles in a variety of physiological process. Indeed, NO has established itself as a polyvalent molecule which plays a decisive role in regulating multiple functions within female reproductive system. In the CL, NO is produced and regulates luteal blood flow, P secretion and apoptosis of luteal cells as well as endothelial cells. This review describes the current investigation for possible roles of NO in the luteolytic cascade within the bovine CL.SRD Young Investigator Award 2009http://www.jstage.jst.go.jp/article/jrd/56/1/56_9/_articl