SITES OF GENE-EXPRESSION FOR VASOACTIVE INTESTINAL POLYPEPTIDE THROUGHOUT THE BRAIN OF THE CHICK (GALLUS-DOMESTICUS)

The peptide neurotransmitter vasoactive intestinal polypeptide (VIP) h as several important functions in vertebrates, particularly, influenci ng the neuroendocrine and autonomic nervous systems both in developing and in adult animals. To document potential brain areas that might pl ay significant functional roles, the distribution of VIP mRNA was exam ined throughout the entire chick brain by using in situ hybridization histochemistry (ISHH). In addition, a VIP binding-site study was compl eted that focused on the lateral septal organ (LSO), a circumventricul ar organ of potential significance in avian species. The areas where V IP message was found included the olfactory bulbs, posterior hippocamp us, parahippocampal area, hyperstriatum, archistriatum/nucleus (n.) ta enia (amygdala), medial part of the LSO, organum vasculosum of the lam ina terminalis, medial preoptic region, bed n. of the pallial commissu re, anterior hypothalamic (hypo.) n., lateral hypo. area (most extensi ve and dense message), periventricular hypo. n., lateral to the parave ntricular n., ventromedial hypo. n., stratum cellulare externum, infer ior hypo. n., infundibular hypo. n., median eminence, three layers wit hin the stratum griseum et fibrosum superficiale, area ventralis of Ts ai, n. tegmenti pedunculopontinus pars compacta (substantia nigra), in tercollicular n., central gray, locus ceruleus, parabrachial n., ventr olateral medulla, reticular pontine area, in and about the n. vestibul aris descendens. When compared with immunocytochemistry that detected the presence of the peptide product VIP, more areas of the brain were found to contain perikarya expressing VIP by using ISHH, particularly in the telencephalon and the mesencephalon. VIP binding sites were fou nd in the lateral portion of the LSO where the blood-brain barrier is not fully developed. Hence, the LSO was found to contain neural elemen ts that synthesize as well as bind VIP. VIP appears to be a useful pep tide for defining major components of the visceral forebrain system in birds. (C) 1997 Wiley-Liss, Inc.