Effects of Retinoic Acid and Progesterone on Reproductive Performance in Retinol-deficient Female Rats ,

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Abstract
It was desired to determine whether administration of retinoic acid, or a combination of retinoic acid plus progesterone, could repair the defects in reproductive performance which occur in retinol-deficient female rats. A reliable degree of retinol deficiency was achieved in virgin female albino rats by feeding a retinol-replete diet from weaning until attainment of a body weight of 80 g, followed by a retinol-free diet until the rats reached 200 g and were mated. One group of 60 rats was fed an unsupplemented retinol-free diet, and two other groups of 48 and 60 rats, respectively, were additionally given all-trans retinoic acid by mixing it into the diet (10 µg/g) or by medicine dropper (375 µg/rat/week). Supplementation of the retinol-free diet with retinoic acid improved weight gains and restored regular estrous cycles in nonpregnant rats and also improved rates of mating and conception. Administration of retinoic acid by dropper was more effective than admixture in the diet. Neither retinoic acid alone nor in combination with 5 mg progesterone/rat/day from the day of conception prevented resorption or death of fetuses. Hemorrhage of the labyrinth and necrosis of the junctional zone of the placenta were characteristic antecedents of late fetal death. Although retinoic acid did not prevent resorption of fetuses in retinol-deficient dams, it supported formation of chorio-allantoic placentas and postponed the time of fetal resorption until approximately day 16 of gestation.