Expression of serotonin 5-HT2C receptors in GABAergic cells of the anterior raphe nuclei.
We have used double in situ hybridization to examine the cellular localization of 5-HT2C receptor mRNA in relation to serotonergic and GABAergic neurons in the anterior raphe nuclei of the rat. In the dorsal and median raphe nuclei 5-HT2C receptor mRNA was not detected in serotonergic cells identified as those expressing serotonin (5-HT) transporter mRNA. In contrast, 5-HT2C receptor mRNA was found in most GABAergic cells, recognized by the presence of glutamic acid decarboxylase mRNA. Such 5-HT2C receptor-positive GABAergic neurons were mainly located in the intermediolateral and lateral portions of the dorsal raphe and lateral part of the median raphe. The present data give anatomical support to a previous hypothesis that proposed a negative-feedback loop involving reciprocal connections between GABAergic interneurons bearing 5-HT2A/2C receptors and 5-HT neurons in the dorsal raphe and surrounding areas. According to this model, the excitation of GABAergic interneurons through these 5-HT2C (and also 5-HT2A) receptors would result in the suppression of 5-HT cell firing.
Serrats
Jordi
J
Department of Neurochemistry, Institut d'Investigacions Biomèdiques de Barcelona (IIBB)--CSIC (IDIBAPS), Rosselló 161, 6th floor, E-08036-Barcelona, Spain.
Mengod
Guadalupe
G
Cortés
Roser
R
D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000378:metabolism*; D005246:Feedback / Q000502:physiology; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007395:Interneurons / Q000166:cytology / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011903:Raphe Nuclei / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D044405:Receptor, Serotonin, 5-HT2C / Q000096:biosynthesis / Q000235:genetics*; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D044405:Receptor, Serotonin, 5-HT2C; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase