STUDIES ON THE MECHANISM OF DECIDUALIZATION

Abstract

A single intra-peritoneal injection of pyrathiazine induces extensive decidualization of the progravid uterus of the rat. This action was considered to be mediated by the release of histamine. The present study was undertaken to show that pyrathiazine, an antihistaminic drug, causes histamine release. Injection of pyrathiazine in rats produced a characteristic histamine-release syndrome, and caused a 2 fold increase in the urinary excretion of histamine. Pretreatment with pyrathiazine protected rats from the lethal effects of challenge doses of histamine-liberator Compound 48/80 but not of histamine. These actions of pyrathiazine demonstrate that it releases histamine in the rat, and that its effectiveness as a decidual inducer is consistent with the postulated role of histamine in decidual induction.