Stress-induced changes in histaminergic system: effects of diazepam and amitriptyline.

The involvement of the histaminergic system in the regulation of weak stress was studied in rats. The parameters examined were the brain receptors and corticosterone (CS) plasma levels. The benzodiazepine diazepam [(2 mg/kg intraperitoneally (IP)] influenced neither foot-shock-induced changes in CS levels nor [3H]-histamine [(3H)-HA] binding site constants, whereas the tricyclic antidepressive amitriptyline (10 mg/kg IP) partially counteracted a plasma CS increase and prevented changes in [3H]-HA binding in the stressed rat brain. These observations are in agreement with the known activities of amitriptyline on monoaminergic metabolism and receptors. Moreover, these data provide further experimental evidence of the functional role of the central histaminergic system in organized stress response.