Abstract

The role of histamine in various stages of female reproductive functions is now understood. The anti-implantation activity of various H₂ receptor blockers had been established earlier by our laboratory. The present studies were conducted to evaluate the local effects of direct intra-uterine injection of H₂ receptor blockers on implantation in albino Wistar rats. The individual administration of ranitidine, famotidine and roxatidine by direct intra-uterine injection on Day 4 of pregnancy in female albino Wistar rats produced 100% anti-fertility activity probably by acting on the H₂ receptors on the blastocyst. Control group animals delivered normal litters. Unilateral injection of roxatidine inhibited implantation in the treated and contralateral uterine horns of rats indicating its systemic as well as local anti-implantation activity while ranitidine and famotidine showed only the local effects on the treated uterine horns suggesting the blockade of locally derived uterine histamine in implantation. Histopathological examination of uterus revealed the absence of morphological damage to the endometrial epithelium. It is concluded that, the intra-uterine application of H₂ receptor blockers prevents conception in rats.

Key words: Anti-implantation activity H₂ receptor blockers, ranitidine, famotidine, roxatidine, intra-uterine injection, implantation.