ROLE OF HORMONES IN THE PROCESSING OF NEURONAL PEPTIDES

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Our goals are to elucidate the mechanisms underlying release of LH- releasing hormone (LHRH) from hypothalamic neurons and its regulation by steroids. Our studies led to the formulation of this working hypothesis: Copper (Cu), co-released with norepinephrine (NE) or a-amidated peptides, modulates LHRH relaease; one such action of Cu is the amplification of prostaglandin E2 (PGE2) stimulation of LHRH release. Adrenal steroids exert a positive input on LHRH relaease in the maturing male rat, by regulating the plasma-membrane machinery involved in the process of Cu- amplified PGE2 (Cu/PGE2) stimulation of LHRH release and by regulating Cu release from neurons impinging on the LHRH neuron. S.A.1 is to elucidate the mechanism(s) by which Cu modulates LHRH release; using explants of the median eminence as a model. We will investigate (i) whether and how a CuNE complex mixture stimulates LHRH release; (ii) whether Cu amplification of PGE2 stimulation of LHRH release is a result of Cu interaction with the opioid receptor and/or Cu inhibition of cAMP efflux. S.A.2. is to elucidate the mechanism(s) underlying adrenal regulation of LHRH release in the maturing male rat; specifically Cu/PGE2- stimulated release. We will (i) characterize the ontogeny of the positive feedback of adrenals steroids on LHRH release and identify the regulatory steroid; (ii) examine the specificity of steroid action on Cu/PGE2 -stimulated release of LHRH by examining the effects on CuHis-, veratridine- and K- induced release; and (iii) study the effect of steroids on the kinetic parameters of Cu and PGE2 interactive sites ad on uptake and release of 67-Cu in various brain regions. S.A3. is to elucidate the biochemical mechanisms underlying Cu homeostasis in the hyothalamus; uptake, release, and intracellular processing. We will (i) further establish the process of 67-Cu release, using veratridine (Na-influx) induced release as a model; (ii) analyse the kinetics of 67-Cu uptake into the releasable pool of Cu; and (iii) study the intracellular processing of newly taken-up CuHis, specifically ligand exchange of the His. Understanding the mechanisms underlying Cu action on the LHRH neuron and steroid regulation of LHRH release in teh maturing male, will provide insight into integrative regulatory processes in the brain and into developmental and hormonally regulated brain functions.