Badura 9603780 Prolactin, a protein hormone secreted by the anterior pituitary gland, is involved in modulating a large variety of physiological and behavioral states in mammals, including lactation, estrous cyclicity, maternal behavior, and immune system function. While prolactin is clearly involved in many different physiological processes, the precise mechanism of action and the ways in which prolactin secretion is controlled under various conditions is not well understood. The primary approach has been to examine how various factors affect the surges of prolactin that occur during stress, lactation, or during the estrous cycle. The problem is that surges of prolactin involve the activation of multiple systems and, therefore, the results from this approach can be very difficult to interpret. Dr. Badura seeks to enhance our understanding of the role of individual modulatory systems to the prolactin response by examining changes in basal prolactin levels that fluctuate throughout the year. She is taking advantage of the fact that prolactin shows a marked annual fluctuation that corresponds with changes in photoperiod, most likely daylength. Indeed Dr. Badura has demonstrated that nonstimulatory daylengths will induce naturally occurring declines in circulating prolactin. Using this model, she will characterize the neurotransmitters within the paraventricular nucleus of the hypothalamus, a major neuroendocrine brain region that regulates pituitary function. Using in vivo microdialysis and HPLC-EC techniques, Dr. Badura will correlate the release and metabolism of neurotransmitters with alterations that are seen in basal prolactin release under different photoperiod conditions. She will also use this model and protocol to untangle some of the potential effects of gonadal steroid hormones on this system in both males and females. In addition, Dr. Badura will examine how these regulatory factors influence pituitary function directly under different environmental conditions. The results from these studies will provide new knowledge in our understanding of neuroendocrine processes. Dissecting the mechanisms by which prolactin regulates apparently unrelated physiological systems will enhance our understanding of the adaptive significance of evolving hormonal systems that possess multiple targets and function.
