Effect of some drugs upon rat brain histamine content

Abstract A modification of the Shore et al. (1959) procedure for the determination of histamine in brain was described in which the interfering substances were efficiently removed by ion-exchange chromatography on Dowex-50 resin. The modified procedure was used to determine the effect of various drugs upon rat brain histamine concentration. Of all the drugs tested only chlorpromazine (20 mg/kg and 40 mg/kg) gave significant increases (20 per cent and 43 per cent, respectively) in histamine levels. Also while 50 mg/kg of benadryl gave a significant decrease of 25 per cent, a dose of 100 mg/kg had no significant effect. The results of measurements of 51 normal rat brains gave a corrected histamine concentration of 0·052 μg/g with a standard error of the mean of 0·001. The histamine was distributed between the brainstem, cerebrum and cerebellum, with the highest concentration present in the brainstem.