The effects of chronic cocaine pretreatment on kindled seizures and behavioral stereotypies

Male Sprague-Dawley rats were implanted with electrodes in the left basolateral amygdala and caudates. After recovery, rats received daily injections of 40 mg/kg cocaine or saline i.p. for 14 days. Daily electrostimulation (400 μA) of the left amygdala, i.e., kindling, was carried out until rats exhibited poststimulation clonic seizures on two consecutive days. Rats treated with cocaine prior to kindling reached criterion significantly faster than the controls. This difference, however, was wholly attributable to the faster kindling observed in subjects (Ss) in which cocaine-induced convulsions had been noted during the daily treatment. Augmentation of behavioral stereotypies was greater and propagation of afterdischarges to the caudate occurred significantly earlier in rats that had received cocaine prior to the initiation of kindling regardless of whether or not convulsions had occurred. These data in conjunction with those of other investigators suggest that chronic cocaine administration may deplete dopamine and thus diminish inhibitory neural function allowing earlier propagation of afterdischarges and augmenting drug-induced stereotypies.