Intrinsic vasoactive intestinal polypeptide (VIP)-containing neurons in the baroreceptor nucleus of the solitary tract in rat.

Vasoactive intestinal polypeptide (VIP)-immunoreactive cell bodies, dendrites and nerve terminals in the nucleus of the solitary tract have been identified with electron microscopic immunocytochemistry in rats. The relatively high concentration of VIP in this nucleus, which corresponds to the primary baroreceptor center, was depleted only insignificantly by uni- or bilateral transection of the solitary tract, which eliminates peripheral neuronal (via glossopharyngeal and vagal nerves) input to the nucleus. Both immunocytochemical and biochemical data suggest that the majority of VIP in the nucleus of the solitary tract is present in intrinsic neurons.