Effect of psychotropic drugs on histamine H2-receptors in rat isolated uterus.

The effects of the monoamine oxidase inhibitors iproniazid, nialamide and phenelzine, the neuroleptics haloperidol and thioridazine, and the benzodiazepines diazepam and clonazepam on histamine H2-receptors were assessed on rat isolated uterus. The monoamine oxidase inhibitors showed a slight non-competitive antihistamine H2 activity, while diazepam and clonazepam were devoid of any action. Haloperidol and thioridazine inhibited in a dose-dependent manner the tonic component of KCl induced contraction, while thioridazine under the same conditions exhibited a slight antihistamine H2 activity. These data show that the drugs tested are devoid of or elicited only a slight antihistamine H2 activity at high non-therapeutic concentrations.