SR 48692-SENSITIVE NEUROTENSIN RECEPTORS MODULATE ACETYLCHOLINE-RELEASE IN THE RAT STRIATUM

The effects of stimulation and blockade of neurotensin receptors on st riatal acetylcholine release were examined in anaesthetized rats using microdialysis. Local perfusion with neurotensin (100 nM) did not infl uence the release of acetylcholine. Application of neurotensin (100 nM ) 30 min after haloperidol (125 mu g/kg, i.p.) increased acetylcholine levels to 188% compared to 120% when haloperidol was administered alo ne. SR 48692 (3-100 mu g/kg, i.p.) dose-dependently reduced the stimul atory effect of neurotensin in the presence of haloperidol. Comparable antagonism was observed with SR 48527, a chemically-related compound with high affinity for neurotensin receptors, but not with SR 49711, i ts low-affinity antipode. These results indicate that high affinity ne urotensin receptors regulate acetylcholine release, when D-2-dopaminer gic inhibitory input is suppressed.