GABAB receptor mRNA in the raphe nuclei: co-expression with serotonin transporter and glutamic acid decarboxylase.
We have used double-label in situ hybridization techniques to examine the cellular localization of GABAB receptor mRNA in relation to serotonin transporter mRNA and glutamic acid decarboxylase mRNA in the rat dorsal raphe, median raphe and raphe magnus nuclei. The degree of cellular co-localization of these markers notably varied among the different nuclei. In the dorsal raphe, cell bodies showing GABAB receptor mRNA were very abundant, the 85% being also labelled for serotonin transporter mRNA, and a low proportion (5%) showing glutamic acid decarboxylase mRNA. In the median raphe, the level of co-expression of GABAB receptor mRNA with serotonin transporter mRNA was significantly lower. Some cells were also identified that contained GABAB receptor mRNA in the absence of either one of the other mRNA species studied. Our results support the presence of GABAB receptors in serotonergic as well as GABAergic neurones in the dorsal and median raphe, providing the anatomical basis for the reported dual inhibitory/disinhibitory effect of the GABAB agonist baclofen on serotonergic function.
Serrats
Jordi
J
Department of Neurochemistry, Institut d'Investigacions Biomèdiques de Barcelona, IIBB-CSIC (IDIBAPS), Rosselló 161, E-08036-Barcelona, Spain.
Artigas
Francesc
F
Mengod
Guadalupe
G
Cortés
Roser
R
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D005968:Glutamate Decarboxylase / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis*; D011903:Raphe Nuclei / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018080:Receptors, GABA-B / Q000096:biosynthesis* / Q000235:genetics; D050486:Serotonin Plasma Membrane Transport Proteins
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D018080:Receptors, GABA-B; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D005968:Glutamate Decarboxylase