LOCATION OF NEURONS THAT EXPRESS REGULATED ENDOCRINE-SPECIFIC PROTEIN-18 IN THE RAT DIENCEPHALON

In situ hybridization for regulated endocrine-specific protein-18 mess enger RNA showed a distinct and limited pattern of expression in the h ypothalamus, midline thalamus, amygdala and hippocampus of the rat. Hi gh levels of regulated endocrine-specific protein-18 messenger RNA wer e found in the magnocellular neurons of the hypothalamic paraventricul ar, supraoptic and accessory nuclei, in the neurons of the periventric ular, medial tuberal, arcuate, lateral and perifornical nuclei, infund ibular stalk, and in the ventrolateral division of the ventromedial nu cleus and compact division of the dorsomedial nucleus. Lower levels of regulated endocrine-specific protein-18 messenger RNA were found in t he parvocellular divisions of the paraventricular nucleus as well. as in the bed nucleus of the stria terminalis, median preoptic nucleus, m edial preoptic nucleus, medial and lateral preoptic areas, subfornical organ, suprachiasmatic nucleus, anterior hypothalamic area, zona ince rta, ventromedial nucleus, dorsomedial nucleus and tuber cinereum. Reg ulated endocrine-specific protein-18 messenger RNA was also found in t halamic structures including the paraventricular, central medial, inte rmediodorsal, anterodorsal, rhomboid and reticular nuclei. Signal was also identified in the medial and lateral habenula, in the central, me dial, basomedial and anterior cortical nuclei of the amygdala, and in the CA1-CA3 and dentate gyrus of the hippocampus. Dopamine may regulat e regulated endocrine-specific protein-18 expression in the CNS becaus e (i) regulated endocrine-specific protein-18 was originally identifie d in melanotropes based on its regulation by dopaminergic agents and ( ii) many of the nuclei that contain regulated endocrine-specific prote in-18 also receive dopaminergic input. The localization of regulated e ndocrine-specific protein-18 in the diencephalon suggests that regulat ed endocrine-specific protein-18 is involved in regulation of limbic a nd autonomic function, neuroendocrine control of salt and water balanc e, reproductive function and feeding behavior.