Summary
After α-methyl-DOPA (α-MD) administration to cats a significant decrease of a conditioned avoidance response (CAR) was observed 8 hours later. In reserpine-pretreated cats α-MD caused a pronounced reduction of CAR which was not reversed by (+)-amphetamine. A subsequent administration of l-DOPA resulted in a dose-dependent CAR reversal. Different possibilities of the central action exerted by α-MD are discussed.
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Burkard, W. P., K. F. Gey, and A. Pletscher: Inhibition of the hydroxylation of tryptophan and phenylalanine by alpha-methyl-dopa and similar compounds. Life Sci. 3, 27–33 (1964).
Carlsson, A., and M. Lindqvist: In-vivo decarboxylation of α-methyl-DOPA and α-methyl metatyrosine. Acta physiol. scand. 54, 87–94 (1962).
Day, M. D., and M. J. Rand: A hypothesis for the mode of action of α-methyldopa in relieving hypertension. J. Pharm. Pharmacol. 15, 221–224 (1963a).
— —: Awakening from reserpine sedation by α-methyl-dopa. J. Pharm. Pharmacol. 15, 631–632 (1963b).
Goldberg, L. I., F. M. Dacosta, and M. Ozaki: Actions of the decarboxylase inhibitor, alpha-methyl-3,4-dihydroxyphenylalanine, in the dog. Nature (Lond.) 188, 502–504 (1960).
Gunne, L. M., and J. Jonsson: Effects of reserpine in rats pretreated with α-methyldopa. J. Pharm. Pharmacol. 16, 774–775 (1963).
Hanson, L. C. F.: The disruption of conditioned avoidance response following selective depletion of brain catecholamines. Psychopharmacologia (Berl.) 6, 100–110 (1965).
—: Evidence that the central effect of amphetamine is mediated via catecholamines. Psychopharmacologia (Berl.) 9, 78–80 (1966).
—: Evidence that the central action of (+)-amphetamine is mediated via catocholamines. Psychopharmacologia (Berl.) 10, 289–297 (1967).
Mason, D. T., and E. Braunwald: Effects of guanethidine, reserpine, and methyldopa on reflex venous and arterial constriction in man. J. clin. Invest. 43, 1449–1463 (1964).
Muscholl, E.: Autonomic nervous system: Newer mechanisms of adrenergic blockade. Ann. Rev. Pharmacol. 6, 107–128 (1966).
Nagatsu, T., M. Levitt, and S. Udenfriend: Tyrosine hydroxylase: The initial step in norepinephrine biosynthesis. J. biol. Chem. 239, 2910–2917 (1964).
Quinton, R. M., and G. Halliwell: Effects of α-methyl DOPA and DOPA on the amphetamine excitatory response in reserpinized rats. Nature (Lond.) 200, 178–179 (1963).
Randrup, A., and I. Munkvad: Role of catecholamines in the amphetamine excitatory response. Nature (Lond.) 211, 540 (1966).
Ray, O. S., and L. W. Bivens: Behavioral effects of l-alpha methyl dopa. Life Sci. 4, 823–826 (1965a).
— —: Effects of l-alpha methyl dopa on discrete trial behavior. Life Sci. 4, 1185 to 1191 (1965b).
Roos, B.-E., and B. Werdinius: The effect of α-methyl DOPA on the metabolism of 5-hydroxytryptamine in brain. Life Sci. 2, 92–96 (1963).
Ross, S. B., and Ö. Haljasmaa: Inhibitors of the enzymatic hydroxylation of phenylalanine and tryptophan by rat liver extract in vitro. Life Sci. 3, 579–587 (1964).
Seiden, L. S., and L. C. F. Hanson: Reversal of the reserpine-induced suppression of the conditioned avoidance response in the cat by l-DOPA. Psychopharmacologia (Berl.) 6, 239–244 (1964).
Shapiro, A. P., and E. Krifcher: Pressor responses to noxious stimuli in hypertensive patients. Effects of guanethidine sulfate and alpha methyldopa. Circulation 30, 671–678 (1964).
Sourkes, T. L.: Inhibition of dihydroxyphenylalanine decarboxylase by derivatives of phenylalanine. Arch. Biochem. 61, 444–456 (1954).
—: Action of α-methyldopa in the brain. Brit. med. Bull. 21, 66–69 (1965).
Stone, C. A., and C. C. Porter: Methyldopa and adrenergic nerve function. Pharmacol. Rev. 18, 569–575 (1966).
— —, L. S. Watson, and C. A. Ross: Pharmacology of decarboxylase inhibitors. In: Hypertension. The second Hahnemann Symposium on Hypertensive Disease. Ed. by A. N. Brest and J. H. Moyer, pp. 417–423. Philadelphia: Lea & Febiger 1961.
Weissman, A., B. Koe, and S. Tenen: Antiamphetamine effects following inhibition of tyrosine hydroxylase. J. Pharmacol. exp. Ther. 151, 339–352 (1966).
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Hanson, L.C.F., Henning, M. Effects of α-methyl-Dopa on conditioned behaviour in the cat. Psychopharmacologia 11, 1–7 (1967). https://doi.org/10.1007/BF00401503
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DOI: https://doi.org/10.1007/BF00401503