VASOACTIVE INTESTINAL PEPTIDE (VIP) - BRAIN DISTRIBUTION, SUBCELLULAR-LOCALIZATION AND EFFECT OF DEAFFERENTATION OF THE HYPOTHALAMUS IN MALE-RATS

We have studied the regional and subcellular distribution of vasoactive intestinal peptide (VIP) in the brain of adult male rat, using a specific radioimmunoassay. Selective deafferentation of the mediobasal hypothalamus (MBH) was also performed in order to investigate the origin of hypothalamic VIP. The highest concentrations of VIP were found in the neocortex, namely the occipital region. The brain stem, the posterior hypothalamus, and the pineal gland contained low amounts of the peptide. VIP was not detectable in the cerebellum and the neurohypophysis. After fractionation, most of the VIP was recovered from the crude mitochondrial fraction of the hypothalamus as well as the parietal cortex. However, a non-negligible portion of the activity was also found in the supernatant suggesting that the peptide is mainly located in nerve endings but also present in neuronal cell bodies and/or axons. Two weeks after complete deafferentation of the MBH, VIP concentrations of the caudal MBH (including the infundibular sulcus, the stalk, part of the ventromedial nucleus and premamillary structures) were decreased by 40%. In contrast, no change in VIP levels were observed in the rostral MBH, organum vasculosum of the lamina terminalis (OVLT), and cortex. This suggests that hypothalamic nerve endings containing the peptide derive from neuronal cell bodies located both outside and within the MBH. © 1979.