In previous studies, the applicant has demonstrated that basal levels of arginine vasopressin (AVP) mRNA are stable in adults and that secretion is tightly coupled to synthesis. In contrast, he found that in prepubertal rats (between weaning and sexual maturity) there is a progressive increase in both hypothalamic AVP mRNA and pituitary AVP. Accordingly, he hypothesizes that two dramatic changes in endocrine balance occurs in development to determine adult levels of AVP message and pituitary content: changes in sodium and fluid intake associated with weaning and onset of secretion of gonadal steroids. This proposal has 5 Specific Aims: 1. Quantify the dynamics of hypothalamic AVP mRNA and pituitary vasopressin content and identify the cellular mechanism(s) regulating AVP synthesis in the maturing rat. 2. In the young rat, determine the impact of osmotic manipulation on vasopressin synthesis and pituitary AVP accumulation and determine the site of regulation of these effects. 3. Determine the influence of gonadal steroids on AVP synthesis and the development of neurohypophyseal AVP stores in the immature rat. 4. Study the interaction of osmotic and steroidal inputs to the regulation of vasopressin synthesis and determine whether they are independent and additive, permissive, or synergistic. 5. Determine the long-term impact of osmotic and steroidal manipulations during the maturational period on vasopressin synthesis and neural lobe AVP content in the adult rat.
