Immediate and long-term effects of opiate antagonists on postictal behaviour following amygdala kindling in the rat

Abstract

Male Wistar rats implanted with bipolar electrodes in the amygdaloid complex were kindled. Subcutaneous injection of naloxone or naltrexone in low doses - 0.12 and 0.24 mg/kg, respectively - dramatically reduced the postictal behavioural depression (BD) at 10 or 60 min. Remarkably, the BD was still reduced one day later. It would appear that the brain mechanisms involved in postictal BD use μ-receptors since BD is quite sensitive to low doses of the preferential antagonists naloxone and naltrexone. The long-term effects, the most novel aspect of these studies, are probably related to immediate effects but could be produced through slow processes or alteration of the response to endogenously released enkephalins.