Co-localization of 5-HT 2A -receptor- and GABA-immunoreactivity in neurones in the periaqueductal grey matter of the rat.
The dorsal half of the midbrain periaqueductal grey matter (dPAG) functions as a midbrain aversive system. Serotonin exerts anti-aversive effects in the dPAG that are mediated by actions at 5-hydroxytryptamine (5-HT)(1A)- and 5-HT(2A)-receptors. Since at the cellular level, 5-HT(2A)-receptor activation has been shown to evoke excitatory responses in the dPAG, it is possible that anti-aversive 5-HT(2A)-mediated effects are mediated indirectly by activation of inhibitory gamma-aminobutyric acid (GABA)ergic interneurones. In rats, immunoreactivity for 5-HT(2A)-receptors was present on the soma and dendrites of neurones throughout the PAG. Co-localization studies revealed that the majority (>90%) of 5-HT(2A)-receptor-labelled cells also showed immunoreactivity for GABA. These findings may provide an anatomical substrate for 5-HT(2A)-mediated anti-aversive effects in the dPAG.
Griffiths
J L
JL
Department of Physiology, The Medical School, University of Birmingham, Birmingham, B15 2TT, UK.
Lovick
T A
TA
D000818:Animals; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010487:Periaqueductal Gray / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D005680:gamma-Aminobutyric Acid