Altered responding to cholecystokinins and dopaminergic agonists following 6-hydroxydopamine treatment in rats.
Production of lesions in the brain dopamine (DA) system by intraventricular injection of 6-hydroxydopamine (6-OHDA) resulted in increased responses to apomorphine (0.5 mg/kg, sc) and reduced responses to methamphetamine (0.15 mg/kg, sc). It also made animals increase responding to cholecystokinin octapeptide (CCK-8; 0.5-2 micrograms, intracerebroventricularly [icv]) and reduce responding to cholecystokinin tetrapeptide (CCK-4; 0.5-2 micrograms, icv). Response changes were quantified by measuring the level of general activity. The result indicates that DA dysfunction can affect not only DA receptor sensitivity but also the sensitivity of the CCK system. The response to CCK-8 was partially blocked by a selective CCK-8 antagonist, proglumide (5 micrograms, icv), a result suggesting the involvement of the CCK-8 receptor system. Thus, manipulation of one neuronal system could induce sensitivity changes in another closely related system.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001921:Brain / Q000187:drug effects; D004298:Dopamine / Q000502:physiology*; D005755:Gastrins / Q000494:pharmacology*; D006892:Hydroxydopamines; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects*; D016627:Oxidopamine; D011377:Proglumide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology*; D013758:Tetragastrin / Q000494:pharmacology*
D005755:Gastrins; D006892:Hydroxydopamines; D013758:Tetragastrin; D008694:Methamphetamine; D016627:Oxidopamine; D011377:Proglumide; D012844:Sincalide; D001058:Apomorphine; D004298:Dopamine