9224804 Badura Prolactin, a protein hormone secreted by the anterior pituitary gland, is involved in a large number of physiological and behavioral processes in mammals, including estrus cyclicity, immune system activation, stress, milk production, and maternal behavior. While this hormone is clearly involved in many different physiological systems, the precise mechanism of action and the ways in which prolactin secretion is controlled remains to be resolved. It is difficult to study not only because of its multiple modes of action but because prolactin surges and chronic secretions appear to be differently regulated. Dr. Badura is using a clever model system to examine the neuroendocrine regulation of prolactin release. She is taking advantage of the fact that prolactin shows a marked annual fluctuation that corresponds with changes in photoperiod, most likely daylength. Dr. Badura will incorporate photoperiodic cues to examine the factors the underlie the regulation of prolactin secretion. She will be concentrating on two neuropeptides, vasoactive intestinal polypeptide and oxytocin. These peptides hormones are likely modulatory factors since they are located in the paraventricular nucleus of the hypothalamus, a brain region that she has previously shown to play an important role in the stimulatory modulation of basal prolactin release. Using state-of-the-art neurochemical and neuroanatomical procedures, Dr. Badura will identify the sites of action and the relative contributions of modulatory factors in the expression of photoperiodic changes in the neuroendocrine control of this physiologically relevant hormone. Dissecting the mechanisms by which prolactin regulates apparently unrelated physiological systems will increase our understanding of the adaptive significance of evolving hormonal systems that possess multiple targets and functions. ***
