Effects of sodium phenobarbital on motor activity and exploration in the mouse: development of tolerance and incidence of withdrawal responses.
Sodium phenobarbital (20 mg/kg) was without significant effect on exploratory head-dipping, but a higher dose (70 mg/kg) significantly reduced the number of head-dips and the time spent head-dipping 0.5 and 8 hr after acute administration. Tolerance developed rapidly, i.e., by day 7 of treatment, to these reductions. Both doses of phenobarbital significantly increased locomotor activity, the increase was more marked for the 70 mg/kg dose and for this dose was greater 8 hr after administration than 0.5 hr. No tolerance developed over 21 days of treatment to the increase in locomotor activity 0.5 hr after drug administration; some tolerance did develop by day 14 to the increase detected 8 hr after drug administration, but this is likely to be metabolic. After 21 days of treatment, sodium phenobarbital was withdrawn. Twenty-four hours after the last dose of 70 mg/kg there was a significant reduction in the time spent head-dipping; there was also significant reduction in locomotor activity, which peaked 48 hr after the last dose.
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S E
SE
UMDS Division of Pharmacology, University of London, Guy's Hospital.
Wilks
L J
LJ
D000818:Animals; D004361:Drug Tolerance; D005106:Exploratory Behavior / Q000187:drug effects*; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D010634:Phenobarbital / Q000009:adverse effects / Q000494:pharmacology*; D011897:Random Allocation; D013375:Substance Withdrawal Syndrome; D013997:Time Factors
D010634:Phenobarbital