3-Methoxytyramine as an indicator of impulse-induced dopamine release in rat brain in vivo.
3-Methoxtyramine and dopamine accumulated in vivo in rat brain after monoamine oxidase inhibition with pargyline HCl. A dose of 100 mg/kg i.p. appeared to inhibit monoamine oxidase completely and led to a linear accumulation of 3-methoxytyramine for the first 90 min. Axotomy of the ascending dopaminergic fiber tract by means of a complete transverse cerebral hemisection almost completely blocked 3-methoxytyramine formation provided that catecholamine synthesis was inhibited with H 44/68 (Methylester of alpha-methyl-p-tyrosine). The dopamine receptor agonist apomorphine, 0.5 mg/kg i.p., decreased, while the dopamine receptor antagonist haloperidol, 2 mg/kg i.p., accelerated 3-methoxytyramine formation. gamma-Butyrolactone, 750 mg/kg i.p., not only decreased 3-methoxytyramine formation per se but also effectively antagonized the haloperidol-induced increase in 3-methoxytyramine accumulation. 3-Methoxytyramine formation after inhibition of monoamine oxidase appears to be a reliable indicator of impulse-induced dopamine release and metabolism.
D015107:4-Butyrolactone / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D003714:Denervation; D004298:Dopamine / Q000378:metabolism* / Q000502:physiology; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D014439:Tyramine / Q000378:metabolism
D008781:Methyltyrosines; D010293:Pargyline; D006220:Haloperidol; D001058:Apomorphine; D015107:4-Butyrolactone; D004298:Dopamine; D014439:Tyramine