IBN-9421529 Michael Ferkin Seasonal reproduction is typical of most species of animals. The mechanisms that underlie seasonal changes are not well characterized. The proposed research examines a new and unique effect of prolactin, a pituitary hormone, on reproductive behavior. There is considerable evidence that prolactin inhibits reproduction. However, recent evidence suggests strongly that high prolactin levels may be needed for the behaviors and physical characteristics necessary for males attract females. The apparent paradoxical role of prolactin will be examined using an unique in vivo model. Prolactin levels tend to be higher during the long days of spring and summer which corresponds to the time of year when animals are reproductively active, whereas, such levels tend to be lower during the short days of fall and winter, and correspond to the time of year when animals are reproductively quiescent. These studies will contribute results that can furnish a new perspective on physiological mechanisms and behaviors facilitating reproduction. They will provide a context within which we can understand the mechanisms underlying reproductive behavior and hormone-behavior relationships and the evolutionary processes leading to seasonal rhythms in reproduction.
