Effect of maternal overnutrition during pregnancy on pituitary gonadotrophin gene expression and gonadal morphology in female and male foetal sheep at day 103 of gestation.

The aim was to determine whether nutritionally mediated restriction of placental growth alters foetal body growth, pituitary gonadotrophin gene expression and gonadal development at Day 103 of gestation. Embryos recovered from adult ewes inseminated by a single sire were transferred, singly, into the uteri of adolescent recipients. After transfer, adolescent ewes were offered a high (H, n=16) or moderate (M, n=12) level of a complete diet. Ewes were slaughtered at 103+/-0.2 days of gestation and foetal blood, brain, pituitary and gonads were collected. Mean placental weight was lower (P< 0.01) in H than in M groups but foetal weight and reproductive organ weights were similar. Maternal nutrition did not influence LHbeta or FSHbeta mRNA expression in either sex but FSHbeta mRNA expression was higher (P< 0.001) in female (n=11) than in male (n=17) foetal pituitaries. Mean foetal plasma gonadotrophin concentrations were not influenced by dietary intake in either sex. Plasma progesterone concentrations were lower (P=0.001) in foetuses derived from H compared with M intake dams. Compared with M foetuses (n=5), ovaries from H foetuses (n=6) had fewer primordial follicles (P< 0.05) and fewer follicles in total (P< 0.005). In contrast, maternal nutritional status did not influence either seminiferous cord or Sertoli cell numbers in male foetuses (H, n=10; M, n=7). It is concluded that high maternal nutrient intakes restricted placental growth and altered foetal ovarian follicular development prior to the end of the second third of gestation. The latter effect was independent of gonadotrophin secretion.Crown