GABAERGIC SYNAPSES UPON NEURONS EXPRESSING SUBSTANCE-P RECEPTORS IN THE NUCLEUS OF THE SOLITARY TRACT - AN IMMUNOCYTOCHEMICAL ELECTRON-MICROSCOPE STUDY IN THE RAT

Morphological substrates for interactions between gamma-aminobutyric a cid (GABA) and substance P upon neurons expressing substance P recepto r (SPR) in the nucleus of the solitary tract (NST) were investigated b y immunocytochemical electron microscopy. In the NST of the rat, many GABA-like immunoreactive axon terminals were in symmetric synaptic con tacts with dendritic profiles; they were observed on nearly a half of the SPR-like immunoreactive dendritic profiles in the medial part of t he caudal half of the NST.