ADRENAL-STEROID REGULATION OF NEUROPEPTIDE Y(NPY) MESSENGER-RNA - DIFFERENCES BETWEEN DENTATE HILUS AND LOCUS-COERULEUS AND ARCUATE NUCLEUS

Regulation by adrenal steroids of neuropeptide Y (NPY) mRNA was invest igated in hilus of the dentate gyrus, arcuate nucleus of hypothalamus and locus coeruleus (LC) of the adult rat brain. Adrenalectomy (ADX) i ncreased NPY mRNA in hilus but decreased NPY mRNA levels in arcuate nu cleus and LC. Using a steroid replacement paradigm previously shown to discriminate between Type I and Type II adrenal steroid receptor medi ated effects, it was shown that Type I receptor stimulation by aldoste rone prevented the ADX-induced increase of NPY mRNA in hilus, whereas Type II receptor stimulation by Ru28362 prevented the ADX-induced decr ease in NPY mRNA in arcuate nucleus and LC. The results for hilus are consistent with evidence for a role of Type I receptors in maintaining levels of a number of gene products associated with neurotransmission . The different regulation in hilus from that in arcuate and LC indica te, along with evidence for regulation of NPY expression by insulin, N GF and cyclic AMP and phorbol esters, that the adrenal steroid regulat ion of NPY gene expression is part of a complex set of regulatory mech anisms that depend on the brain region and cell type.