Three groups of amygdala-kindled rats received 10 bidaily treatment trials:
On each trial, the drug-before group received a diazepam (2.5 mg/kg ip) in
jection 1 hr before a convulsive stimulation, the drug-after group received
a diazepam injection 1 hr after a stimulation, and the vehicle control gro
up received a vehicle injection either 1 hr before or 1 hr after a stimulat
ion. After treatment, only the drug-before group displayed significantly lo
nger forelimb clonus under the influence of diazepam (that is, they display
ed contingent tolerance to diazepam's anticonvulsant effect) and significan
tly longer forelimb clonus while drug free. Following a 14-day retention pe
riod, the rats in the drug-before group retained significant levels of cont
ingent tolerance but did not display significant increases when tested drug
free. These data suggest that compensatory responses do not play a causal
role in the expression of contingent tolerance.