Effect of stress on brain histamine.

Stress of short duration (5 min) resulted in a significant increase in plasma corticosterone level and a significant decrease in the midbrain histamine concentration in rats. Exposure to 15 min stress caused a significant elevation in the hypothalamic histamine level. Stress of longer duration (30 or 60 min) did not affect hypothalamic, cortical or midbrain histamine concentration although plasma corticosterone level remained elevated. Repeated exposures of rats of 15 min stress did not significantly alter histamine concentration of any of the brain regions studied. Plasma corticosterone concentration was only 28% of that observed in animals exposed to single 15 min stress. Present data suggest a role of brain histamine in response to stress.