PT  - JOURNAL ARTICLE
AU  - EVANS, HUGH L.
AU  - GHISELLI, WILLIAM B.
AU  - PATTON, ROBERT A.
TI  - DIURNAL RHYTHM IN BEHAVIORAL EFFECTS OF METHAMPHETAMINE, <em>p</em>-CHLOROMETHAMPHETAMINE AND SCOPOLAMINE
DP  - 1973 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 10--17
VI  - 186
IP  - 1
4099  - http://jpet.aspetjournals.org/content/186/1/10.short
4100  - http://jpet.aspetjournals.org/content/186/1/10.full
SO  - J Pharmacol Exp Ther1973 Jul 01; 186
AB  - Rats were housed and tested under a controlled cycle of 12 hours light-12 hours dark. Effects of drugs on free-operant avoidance and fixed-interval performance varied from enhancement to depression, depending on the stage of the light-dark cycle at which the drug was administered. Methamphetamine produced the greatest increase in lever pressing when administered during the dark period, regardless of whether responding was maintained by food or by electric shock. This effect appeared to be independent of diurnal differences in base-line response rates. Methamphetamine increased locomotor activity at least as much during the light as during the dark, which suggests a dissociation between effects on operant behavior and effects on locomotor activity. α-Methyltyrosine was a more effective antagonist of methamphetamine effects in the light than in the dark. Unlike methamphetamine, p-chloromethamphetamine was more effective in increasing responding during the light period. The dose of scopolamine which was most effective in increasing avoidance responding varied from 0.2 mg/kg in the dark to 0.8 mg/kg in the light. Results are discussed with reference to reported diurnal rhythms in behavioral toxicity and in brain amines. © 1972 by The Williams & Wilkins Co.