Metabolism of 3H-dopamine continuously perfused through push-pull cannulas in rats' brains: modification by amphetamine or prostaglandin F2 alpha.
Using perfusion cannulas implanted in the lateral cerebroventricles, the metabolism of a trace concentration of 3H-dopamine, continuously presented, was investigated in rats performing an operant for food reinforcement. The subjects were mature, drug-naive, male Long-Evans rats. Perfusate contained measurable quantities of 3H-3,4-dihydroxyphenylacetic acid (3H-DOPAC), 3H-3-methoxy-4-hydroxyphenylacetic acid (3H-homovanillic acid, 3H-HVA), 3H-3-methoxytyramine (3H-3-MT) and the 3H-noradrenaline metabolite, 3H-3-methoxy-4-hydroxyphenylethyleneglycol (3H-MHPG). Systemic injection of d-(1.5 mg/kg) or 1-(3.0 mg/kg) amphetamine resulted in decreased quantities of 3H-DOPAC, 3H-HVA and 3H-MHPG in perfusate with a concurrent decrease in fixed-ratio 20 behavior. Addition of prostaglandin F2 alpha (10 ng/microliters perfused at a rate of 10 microliters/minute) had no effect on the rats' fixed-ratio 20 behavior or rectal temperature, but resulted in decreased quantities of 3H-DOPAC, 3H-HVA and 3H-MHPG in perfusate. It is concluded that this methodology allowed us to monitor drug-induced changes in CNS dopaminergic and noradrenergic function in conscious rats engaged in schedule-controlled operant behavior. Furthermore, a trace concentration of PGF2 alpha in perfusion medium caused changes in 3H-dopamine metabolism in a manner similar to that of systemically administered amphetamines.
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D002404:Catheterization / Q000379:methods; D002552:Cerebral Ventricles; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D010477:Perfusion / Q000379:methods; D011460:Prostaglandins F / Q000494:pharmacology*; D051381:Rats; D014316:Tritium
D011460:Prostaglandins F; D014316:Tritium; D000661:Amphetamine; D003913:Dextroamphetamine; D004298:Dopamine