Local modulation of the 5-HT release in the dorsal striatum of the rat: anin vivo microdialysis study

Using in vivo microdialysis in freely moving rats, we examined the involvem ent of major striatal transmitters on the local modulation of the 5-HT rele ase. Tetrodotoxin reduced the striatal 5-HT output to 15-20% of baseline. T he selective 5-HT1B receptor agonist CP 93129 (50 muM) reduced (50%) and th e 5-HT2A/2C receptor agonist DOI (1-100 muM) increased (220%) the 5-HT outp ut. Neither GABA nor baclofen (100 nM-100 muM) altered the 5-HT output. The glutamate reuptake inhibitor L-trans-PDC (1-4 mM) raised 5-HT to 280% of b aseline. This effect was not antagonized by the NMDA receptor antagonist MK -801 (0.5 mg/kg i.p.). Local MK-801 (10-100 muM) did not significantly alte r the 5-HT output. Finally, neither carbachol (10-100 muM) nor quipirole (1 0 muM-l mM) affected 5-HT. These data suggest that the striatal 5-HT releas e is influenced by local serotonergic and glutamatergic (but not GABAergic) inputs. (C) 2000 Elsevier Science B.V. All rights reserved.