The increase of histamine levels in the amygdala caused by histidine administration and the suppression of muricide in thiamine deficient rats.

The effects of histidine treatment on histamine levels in brain regions and the muricidal suppression in thiamine deficient rats were examined. Intraperitoneal administration of L-histidine significantly increased the histamine levels in several regions of normal and thiamine deficient rats. A dose of 200 mg/kg of histidine suppressed muricide induced by thiamine deficiency. The histamine levels of those thiamine-deficient killer-rats, whose muricide was suppressed by histidine treatment, were significantly higher in the amygdala, striatum and hypothalamus than of those whose muricide was not suppressed. It is suggested that the activation of central histaminergic neuron systems, especially in the amygdala, may underlie the mechanism of muricidal suppression by histidine treatment in thiamine deficient rats.