Intrastriatal kainic acid elicits functional supersensitivity of muscarinic receptors regulating dopamine release
Versace, P.; Bocchieri, P.; Marchi, M.; Raiteri, M.
Neurochemistry International 11(2): 183-188
ISSN/ISBN: 0197-0186 PMID: 20501160 DOI: 10.1016/0197-0186(87)90008-8
Acetylcholine enhanced in a concentration-dependent way the K+ (15 mM)-evoked release of [3H]dopamine from synaptosomes isolated from rat corpus striatum and prelabeled with the radioactive catecholamine. The concentration-effect curve of ACh obtained in presence of 1.2 mM Ca2+ was progressively shifted to the left when [Ca2+] was lowered to 0.4 and to 0.2 mM. Intrastriatal injections of kainic acid reduced (70%) the uptake of [3H]choline in synaptosomes prepared 8 days after the lesion but did not affect significantly the uptake of [3H]dopamine. Also the release of [3H]dopamine evoked by K+ was minimally affected by kainic acid treatment. In contrast, acetylcholine (tested in presence of 1.2 or 0.2 mM Ca2+) was much more effective in enhancing [3H]dopamine release in synaptosomes from kainic acid-lesioned than from unlesioned striata. The results suggest that muscarinic receptors located on dopamine nerve terminals undergo supersensitivity following intrastriatal kainic acid injection.