Effects of fencamfamine on single unit activity of mesencephalic dopaminergic neurons in rats.
Systemic fencamfamine (0.5-16 mg/kg, i.v.) significantly but incompletely inhibited spontaneous activity of nigrostriatal and mesolimbic/mesocortical dopamine (DA) neurons. Inhibition was reversed by haloperidol (0.1 mg/kg, i.v.) and prevented by pretreatment with alpha-methyltyrosine (50 mg/kg, i.v.) plus reserpine (5 mg/kg, i.p.). Pretreatment with alpha-methyltyrosine alone attenuated inhibition at high but not low doses of fencamfamine. Microiontophoresed fencamfamine had little direct effect on DA neurons and did not consistently modulate the effects of co-microiontophoresed DA. In contrast, systemic fencamfamine blocked the inhibitory effects of low doses of apomorphine (10-40 micrograms/kg, i.v.). Fencamfamine appears to be an indirect DA agonist which interacts with both vesicular and newly synthesized DA storage pools. Fencamfamine may also cause a rapid desensitization to the effects of DA autoreceptor stimulation.
Matthews
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RT
Department of Anatomy, College of Medicine, Texas A & M University, College Station.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004298:Dopamine / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006220:Haloperidol / Q000008:administration & dosage / Q000494:pharmacology; D007275:Injections, Intravenous; D007478:Iontophoresis; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008781:Methyltyrosines / Q000008:administration & dosage / Q000494:pharmacology; D009636:Norbornanes / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D009636:Norbornanes; D019805:alpha-Methyltyrosine; D012110:Reserpine; D006220:Haloperidol; C020900:fencamfamine; D004298:Dopamine