title: Evidence for GABA control of serotonin metabolism in the rat suprachiasmatic area.
abstract: Changes in endogenous serotonin (5-HT) metabolism after in vivo stimulation of GABAergic transmission were investigated in the rat suprachiasmatic area (SCA). Activation of GABA transmission was performed by systemic administration of either amino-oxyacetic acid: AOAA, a GABA-transaminase inhibitor or RS baclofen, a GABA B agonist. After drugs administration, the amounts of endogenous 5-HT and 5-HIAA were measured. The release and synthesis of 5-HT were investigated in vitro, using a static incubation of tissue fragments. AOAA or RS baclofen induced an increase in endogenous 5-HT content but did not affect 5-hydroxyindole-acetic acid (5-HIAA). Both drugs induced an increase in the release and synthesis of 5-HT. Detailed study of the effects of AOAA over time on 5-HT metabolism showed that the increase in 5-HT release preceded the increase in amine synthesis. These results suggest that the in vivo stimulation of GABA transmission induces an increase in metabolic activity of the 5-HT neuronal system in the SCA. This effect may likely be mediated via activation of GABA B receptors.
authors.affiliation: INSERM U6 and CNRS UA 634 280, Boulevard Ste Marguerite, 13009 Marseille Cedex, France.
authors.forename: A M
authors.initials: AM
authors.lastname: François-Bellan
authors.forename: M
authors.initials: M
authors.lastname: Héry
authors.forename: M
authors.initials: M
authors.lastname: Faudon
authors.forename: F
authors.initials: F
authors.lastname: Héry