A corticotropin releasing hormone receptor antagonist does not delay parturition in rats

Objective: To determine the effects of CP-154, 526, a corticotropin releasi ng hormone (CRH) receptor antagonist, on the length of normal rat gestation . Study Design: Twenty-four timed-pregnant Sprague-Dawley rats were purchased for this study. The drug and placebo were administered to the animals usin g an osmotic pump surgically inserted in the dorsal subcutaneous space. Six animals received 6 mg/kg/day of the drug, six animals received 12 mg/kg/da y of the drug and twelve animals received the placebo. The gestational peri od, weight of each pup and number of pups in each litter were recorded and compared in the drug group versus placebo group. Results: No difference was noted in the gestational period of the drug and placebo rats. The mean weight of pups in both the drug and placebo groups w as 6.18 g. The number of pups per litter were similar in the drug and placebo groups. Conclusion: Antagonism of CRH receptors in rats has no effect on the length of gestational period, pup weight or number of pups per litter. Further st udies are needed to define the role of CRH and its antagonism in primate pr egnancy, as has been done in sheep.