ABSTRACT
Immunocytochemical staining technique by using specific antibody against 5-HT1A receptor subtype (5-HT1AR) wasused to observe the distribution of 5-HT1AR immunoreactivity in the rat nervous system. The highest level of 5-HT1AR im-munoreactivity was observed in piriform cortex, septum, ventraldorsal thalamic nucleus, reticular thalamic nucleus, basolateralamygdaloid nucleus, Purkinje cell layer, red nucleus, facial nucleus and nucleus of the trapezoid body. Considerably weaker im-munoreactivity was detected in hippocampus, frontal cortex, mediodorsal thalamic nucleus, interpeduncular nucleus, mesen-cephalic trigeminal nucleus, dorsal raphe nucleus, spinal trigeminal nucleus, the superficial layers of the spinal dorsal horn, dor-sal root and trigeminal nerve ganglia, Very weak immunoreactivity was found in the olfactory bulb, caudate putamen,globus pal-lidus, nucleus diagonal band, bed nucleus stria terminalis, habenular nucleus, substantia nigra and superior olive. The presentresults indicate that 5-HT1AR immunoreactive structures are widely distributed in the rat nervous system and might play impor-tant role in mediating the multiple effects of 5-HT in the nervous system.