The interaction between spontaneous convulsions and tolerance to hexobarbital in the abstinence after chronic barbital treatments in the rat.

An earlier study had shown a decreased tolerance to hexobarbital after electrically induced convulsions in the abstinence after chronic barbital treatments in the rat. The effect of spontaneous convulsions was investigated in the present study.In two experiments tolerance was induced by treatment with barbital in the drinking water. Two treatment periods with a total duration of about 55 weeks were given in each experiment. The average consumption of barbital was approximately 200 mg/kg/day during the last part of the treatments. In the abstinence after the second treatment period tolerance was measured with a hexobarbital threshold method. Convulsions were recorded with a jiggle cage. Records were obtained from all barbital treated animals during the first three days of abstinence.In both experiments the hexobarbital thresholds were reduced in barbital treated animals if a convulsion had occurred within the 25 hour period prior to a threshold determination performed on the third abstinent day. If no convulsion had occurred there was a more marked tolerance to hexobarbital.The convulsion which is regarded as a sign of physical dependence can thus reduce the tolerance to hexobarbital in the abstinence after chronic barbital treatments. The convulsion could not only be the sign but also the means to at least temporarily decrease physical dependence.