Distribution of 5-HT2A receptor immunoreactivity in the rat amygdaloid complex and colocalization with γ-aminobutyric acid.
The 5-HT2A receptor (5-HT2Ar) is located in a variety of excitatory and inhibitory neurons in many regions of the central nervous system and is a major target for atypical antipsychotic drugs. In the present study, an immunoperoxidase experiment was used to investigate the distribution of 5-HT2Ar immunoreactivity in the rat amygdaloid complex. In the basolateral amygdala, the colocalization of 5-HT2Ar with inhibitory transmitter γ-aminobutyric acid (GABA) was studied using double-immunofluorescence confocal microscopy. The staining pattern obtained was colchicine-sensitive. In fact, pretreatment with colchicine increased the number of 5-HT2Ar-immunoreactive somata. Accordingly, with the exception of the intercalated nuclei, the amygdaloid complex of colchicine-injected rats exhibited a high density of 5-HT2Ar-IR somata. Morphological analyses indicated that 5-HT2Ar was located on both excitatory and inhibitory neurons in the rat amygdaloid complex. In addition, double-immunofluorescence observations revealed that the great majority of GABA-immunoreactive neurons in the basolateral amygdala exhibited 5-HT2Ar immunoreactivity (66.3%-70.6% depending on the nucleus). These data help to clarify the complex role of the 5-HT2Ar in the amygdaloid complex suggesting that this receptor can regulate amygdaloid activity by acting on different neuronal populations.
Department of Veterinary Morphophysiology and Animal Productions, University of Bologna, Ozzano dell'Emilia, Bologna 40064, Italy. cristiano.bombardi@unibo.it
Cristiano
C
Bombardi
D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D003078:Colchicine / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005455:Fluorescent Antibody Technique / Q000379:methods; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D008297:Male; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A / Q000032:analysis / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D050257:Tubulin Modulators / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000378:metabolism*
D044402:Receptor, Serotonin, 5-HT2A; D050257:Tubulin Modulators; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D003078:Colchicine