LOCALIZATION OF C-TYPE NATRIURETIC PEPTIDE MESSENGER-RNA IN RAT HYPOTHALAMUS

Central or peripheral administration of C-type natriuretic peptide (CN P) affects numerous neuroendocrine systems, including the hypothalamo- pituitary-gonadal, hypothalamo-pituitary-adrenocortical and hypothalam o-neurohypophysial axes. The present report characterizes the distribu tion of CNP mRNA in hypothalamus, providing the first definition of CN P-containing neuroendocrine circuits. In situ hybridization histochemi cal analysis revealed high expression of CNP mRNA in the anteroventral periventricular nucleus (AVPv) and in hypothalamic arcuate nucleus (A RC). Hybridization signals of significantly lower intensity were seen in the medial, median and periventricular preoptic area, the supraopti c, dorsomedial, ventral premammillary and lateral mammillary nuclei an d in the posterior hypothalamic area. A few scattered CNP mRNA contain ing cells were visualized in the medial parvocellular paraventricular nucleus, posterior magnocellular paraventricular nucleus and lateral h ypothalamic area. In the AVPv and ARC the pattern of CNP mRNA distribu tion paralleled that of ANP mRNA. The results indicate a distribution of CNP mRNA associated with key neuroendocrine systems, and underscore s the potential importance of this novel natriuretic peptide in neuroe ndocrine regulation.