IN normal striata, pre-treatment with the D-1 antagonist SCH 23390 (250 and 25 mug kg-1, s.c.) completely and lastingly prevented the D-2 antagonist renioxipride (REM) from increasing acetylcholine (ACh) release; post-treatment did not affect REM action. In alpha-methyl-p-tyrosine (alpha-MpT) dopamine (DA)-depleted striata, however, pre-treatment with SCH 23390 resulted in a transient impairment of REM induced stimulation of ACh release but post-treatment still had no effect. Two different mechanisms therefore seem to be involved in D-2 antagonist-induced stimulation of ACh release; the antagonists indirectly activate a D-1 receptor-mediated facilitatory mechanism regulating cholinergic function, and directly block a D-2 receptor-mediated inhibitory one. In normal rats, in an early phase after D-2 antagonist administration, only the first mechanism is operative; in a later phase, both mechanisms cooperate in the stimulation of ACh release. When DA release is impaired by alpha-MpT, the D-2 inhibitory receptor mechanism becomes more important than the D-1 facilitatory one in controlling ACh release.
Scheda prodotto non validato
Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo
Titolo: | NEUROLEPTICS INCREASE STRIATAL ACETYLCHOLINE-RELEASE BY A SEQUENTIAL D-1 AND D-2 RECEPTOR MECHANISM |
Autori: | |
Data di pubblicazione: | 1993 |
Rivista: | |
Abstract: | IN normal striata, pre-treatment with the D-1 antagonist SCH 23390 (250 and 25 mug kg-1, s.c.) completely and lastingly prevented the D-2 antagonist renioxipride (REM) from increasing acetylcholine (ACh) release; post-treatment did not affect REM action. In alpha-methyl-p-tyrosine (alpha-MpT) dopamine (DA)-depleted striata, however, pre-treatment with SCH 23390 resulted in a transient impairment of REM induced stimulation of ACh release but post-treatment still had no effect. Two different mechanisms therefore seem to be involved in D-2 antagonist-induced stimulation of ACh release; the antagonists indirectly activate a D-1 receptor-mediated facilitatory mechanism regulating cholinergic function, and directly block a D-2 receptor-mediated inhibitory one. In normal rats, in an early phase after D-2 antagonist administration, only the first mechanism is operative; in a later phase, both mechanisms cooperate in the stimulation of ACh release. When DA release is impaired by alpha-MpT, the D-2 inhibitory receptor mechanism becomes more important than the D-1 facilitatory one in controlling ACh release. |
Handle: | http://hdl.handle.net/11584/35715 |
Tipologia: | 1.1 Articolo in rivista |