CIRCADIAN VARIATIONS IN THE EFFECT OF ALPHA-METHYL-P-TYROSINE ON AVOIDANCE-LEARNING

Circadian variations in α-methyl-p-tyrosine's (αMT) disruption of active avoidance acquisition were studied. αMT administered between 11.0 and 13.00 h, 17.00 and 19.00 h and 23.00 and 01.00 h impaired learning, but αMT administered between 05.00 and 07.00 h did not impair learning. The time of αMT ineffectiveness corresponds with the reported circadian peak in brain catecholamines, suggesting that the circadian susceptibility rhythm of αMT depends upon circadian fluctuations of brain catecholamines. © 1979 Springer-Verlag.