Anti-ovulatory activity of H2 receptor blockers in albino rabbits - A preliminary study

Objective To evaluate the anti-ovulatory activity of H-2 receptor blockers (ranitidine, famotidine and roxatidine) in albino rabbits considering the role of histamine in ovulation. Method The drugs were orally administered once daily for three days to adult female rabbits weighing between 1.3-2.0 kg (four groups of three animals). The control group received the 1% weight/volume gum acacia suspension. Thirty minutes after the administration of the last dose, a freshly prepared 0.4 % solution of cupric acetate was administered to each animal intravenously via the marginal ear vein (4 mg/kg body weight) to induce ovulation. To assess ovulation, laparotomy was carried out 48 h after cupric acetate injection. The ovaries were exposed, bleeding points on each ovary were counted, and the ovaries and uteri were subjected to histopathological evaluation. Results Based on the number of bleeding points (ovulation sites) observed on the ovary, H-2 blockers showed varying degrees of anti-ovulatory activity. Roxatidine exerted the most pronounced activity. Histopathological observations of uterus and ovary confirmed the aforementioned observations. Conclusion H-2 receptor blockers appeared to inhibit the cupric acetate-induced ovulation in albino rabbits. Our results seem to confirm the role of histamine in ovulation reported by other authors.