Isradipine blocks cocaine's ability to facilitate pressing for intracranial stimulation

Using rats pressing for rewarding electrical intracranial stimulation of the medial forebrain bundle, it was found that a single administration of isradipine blocked the rate-enhancing effects of cocaine (5.0 mg/kg) at doses of 3.0 and 10.0 mg/kg. Also, when isradipine (3.0 mg/kg) was administered alone (without cocaine) for 5 consecutive days, pressing for intracranial stimulation was not reduced relative to placebo levels. In another experiment, isradipine (3.0 mg/kg) persistently blocked the rate-enhancing effects of cocaine (5.0 mg/kg) across 5 consecutive days. These results support the continued investigation of isradipine as a useful adjunct to other treatments for cocaine addiction.