Differences in effects of Ca2+ channel antagonists on dopamine metabolism in the limbic and extrapyramidal dopaminergic structures.
The effect of single and multiple administration of Ca2+ channel antagonists, nifedipine and verapamil, on concentrations of dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), was investigated in the mesolimbic (cortex, nucleus accumbens) and extrapyramidal (striatum) structures in Wistar rats. A single dose of nifedipine (10 mg/kg IP) produced some activation of the dopaminergic system in both cortex (increase in DOPAC) and n. accumbens (increase in HVA); verapamil (20 mg/kg IP) produced an increase in HVA in the cortex only. Chronic treatment with either Ca2+ channel antagonist produced more marked activation of dopamine metabolism in the cortex and nucleus accumbens. Those changes were most expressed 1 h after the last treatment, but lasted for at least 24 h. No changes in dopamine metabolism were observed in the striatum. The present data suggest that Ca2+ channel antagonists after chronic treatment specifically activate the dopaminergic system in limbic structures.
Antkiewicz-Michaluk
L
L
Department of Biochemistry, Polish Academy of Sciences, Krakow, Poland.
Romańska
I
I
Vetulani
J
J
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015102:3,4-Dihydroxyphenylacetic Acid; D014700:Verapamil; D009543:Nifedipine; D004298:Dopamine; D006719:Homovanillic Acid