Involvement of NMDA receptor mechanisms in the modulation of serotonin release in the lateral parabrachial nucleus in the rat.

摘要

Microdialysis was employed to investigate whether N-methyl-d-asparatate (NMDA) glutamate receptor mechanisms are involved in the modulation of serotonin (5-hydoxytryptamine, 5-HT) release in the region of the lateral parabrachial nucleus (LPBN) in freely moving rats. Perfusion of NMDA (10 and 50 microM) through the microdialysis probe significantly enhanced extracellular concentrations of 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the LPBN area. Local perfusion of the NMDA antagonist dizocilpine (MK801, 10 and 50 microM) did not change the basal 5-HT and 5-HIAA levels in the LPBN area. MK801 (10 microM) administered together with NMDA antagonized the stimulant effect of NMDA (10 microM). The intake of 0.3M NaCl and water induced by subcutaneous injections of the diuretic furosemide (FURO, 10 mg/kg) and the angiotensin converting enzyme inhibitor captopril (CAP, 5 mg/kg) produced significant increases in the 5-HT and 5-HIAA concentrations in the LPBN area. The increased levels of 5-HT and 5-HIAA caused by the combined treatment with FURO and CAP were attenuated by perfusion of MK801 (10 microM). These results indicate the participation of NMDA receptors in the control of 5-HT release in the LPBN area.