Differential involvement of voltage-dependent calcium channels in apomorphine-induced hypermotility and stereotypy.
The involvement of the voltage-dependent calcium channel in behavioral effects of apomorphine was tested in naive rats and in animals which were morphine-abstinent or were subjected to chronic electroconvulsive treatment (ECS). In naive rats a calcium channel blocker, nifedipine, which by itself does not affect locomotor activity, inhibited the locomotor stimulation induced by apomorphine, while it facilitated stereotyped behavior. Morphine-abstinent and ECS-treated rats displayed elevated responsiveness to apomorphine, reflected by hypermotility and stereotyped behavior after a dose of 1 mg/kg IP that does not produce overt behavioral effects in naive animals. Nifedipine, 5 mg/kg IP, significantly reduced hypermotility produced by apomorphine in morphine abstinent or ECS-treated rats. The calcium channel blocker did not, however, antagonize enhanced stereotyped behavior. The results indicate that apomorphine hypermotility is controlled by dihydropyridine calcium channels and that enhancement of calcium channel density produced by morphine abstinence and by chronic ECS potentiates the hypermotility response. Calcium channels seem to be differently involved in control of apomorphine-induced hypermotility and stereotypy.
Antkiewicz-Michaluk
L
L
Institute of Pharmacology, Polish Academy of Sciences, Kraków.
Michaluk
J
J
Romańska
I
I
Vetulani
J
J
D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D004594:Electrophysiology; D004597:Electroshock; D008297:Male; D009020:Morphine / Q000009:adverse effects; D009043:Motor Activity / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013239:Stereotyped Behavior / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome / Q000378:metabolism / Q000523:psychology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D009020:Morphine; D009543:Nifedipine; D001058:Apomorphine