The positive relationship between Sertoli cell number and testicular size emphasizes the importance of determining factors involved in the regulation

The zinc finger transcription factor Gata4, is associated with gonadal development in many species. The present study characterizes temporal and spat

The objective of this study was to evaluate the effects of parenteral administration of L-arginine (Arg) to well-fed twin-bearing ewes from day (d) 100 of pregnancy to birth on fetal growth, body composition and neonatal behavior. Ewes received an i.v. bolus of either 345 μmol Arg-HCl/kg bodyweight or saline solution (control) 3 times a day. At d 140 of pregnancy, Arg-supplemented and control ewes were euthanized and fetal weight and fetal organ weight recorded, and maternal and fetal plasma concentrations of amino acids, hormones and metabolites analyzed. A subset of ewes was allowed to lamb and birth weight, body dimensions and behavior of the lambs in the first 2 hours(h) following birth recorded and blood samples collected. At d 140 of pregnancy, fetal weight internal organ weights were unaffected by treatment with the exception of brown fat stores which were increased by 16% in fetuses from Arg-supplemented ewes relative to controls (P < 0.05). At birth, there was an interaction (P = 0.06) between treatment and sex for birth weight of the lamb. The ewe lambs from Arg-supplemented ewes were 12% (P < 0.05) heavier at birth compared with controls whereas birth weight of male lambs did not differ. These results indicate that maternal Arg supplementation enhanced brown fat stores in the fetus and countered some effect of fetal growth restriction due to litter size in female lambs. Increasing birth weight of female lambs and enhancing brown fat stores of all lambs may have important implications for lamb survival and postnatal growth.

Chinese Meishan (MS) boars have smaller testes due to fewer Sertoli cells compared with White Composite (WC) boars. The objective was to describe Sertoli cell development relative to circulating FSH concentrations in fetal and neonatal MS and WC boars. Testes and blood samples were collected on days 60, 75, 90 and 105 postcoitum (dpc) and 1, 7, 14 and 25 postpartum (dpp). One testis was immunostained for GATA4 or Ki67 antigen to evaluate total and proliferating Sertoli cell numbers respectively. Testicular size was greater (P<0.01) in WC than MS boars at all ages, associated with a greater mass of interstitial tIssue. Tubular mass (P<0.01) was greater in prenatal WC boars, but postnatally increased more rapidly (P<0.001) in MS boars, exceeding WC boars by 25 dpp. Sertoli cell numbers increased with age, was greater (P<0.001) in WC than MS boars during prenatal development but increased rapidly (P<0.01) by 1 dpp in MS and thereafter was similar in both breeds. The proportion of Ki67-positive Sertoli cells was maximal at 90 dpc, declining thereafter, did not differ between breeds through 7 dpp, but was greater (P<0.05) in WC than MS boars at 14 and 25 dpp. Plasma FSH concentrations were greater (P<0.05) in WC than MS boars at 75 dpc. FSH concentrations were elevated at 105 dpc (MS) and 1 dpp (WC) but declined thereafter with advancing postnatal age in both breeds. This study illustrates that late gestation represents the period of maximal Sertoli cell proliferation. Despite asynchronous Sertoli cell population growth between breeds during early postnatal life, differential mature Sertoli cell numbers and testicular size are probably due to differences in duration of the proliferative period after 25 dpp, potentially regulated by Sertoli cell maturation and blood-testis barrier formation. These events were not associated with fetal or early postnatal changes in FSH secretion.

The underlying molecular mechanisms that control milk yield and milk protein yield in domestic animals are not completely understood. In this study, the galactopoietic response to exogenous growth hormone (GH) was used as an experimental model to investigate the role of translation initiation and elongation in the regulation of milk protein synthesis in the mammary gland. A slow-release formula of commercially available GH was administered via a single subcutaneous injection to 4 lactating cows (GH group). A further 4 cows were given a single subcutaneous injection of saline (control group). Changes in mRNA transcript level and protein phosphorylation status of key members of the mammalian target of rapamycin (mTOR) pathway were assessed in mammary gland tissues of these animals using quantitative real-time PCR and Western blotting. The GH treatment enhanced the phosphorylation of ribosomal protein S6 and increased the protein abundance of eukaryotic initiation factor 4E (eIF4E) and eukaryotic elongation factor 2 (eEF2) proteins in the mammary gland of GH-treated animals. These results indicate a link between milk protein synthesis and the regulation of mRNA translation. The GH treatment did not change mRNA abundance of ribosomal protein S6, eIF4E, and eEF2, nor did it change the mRNA (mTOR, eEF2 kinase) or protein abundance of eEF2 kinase. These results demonstrate that GH administration changes mRNA translation initiation and elongation possibly via the mTOR pathway (suggested by the increased levels of ribosomal protein S6 phosphorylation), indicating that the mTOR pathway might be a potential control point in the regulation of milk protein synthesis in the mammary gland.

Low birth weight has profound implications for perinatal mortality and morbidity in lambs, causing higher mortality and lower growth potential. Low birth weight, as a consequence of fetal growth restriction, occurs in undernourished and multiple pregnancies, where hypoxia and oxidative stress could play a critical role. Our aim was to establish the effects of nutritional deprivation and pregnancy rank on fetal growth, oxygenation, and oxidative status in sheep pregnancies under extensive Patagonian conditions. At 30 days after mating, single- and twin-bearing ewes were offered only natural pasture (undernutrition group) or natural pasture plus concentrate supplementation (well-nourished group). At day 140 of gestation, blood gases and redox status were evaluated in venous cord blood, and fetal biometric characteristics were obtained after cesarean section. Both maternal undernutrition and twinning led to decreased oxygen supply to the fetuses (p = 0.016 and p = 0.050, respectively), which was associated with decreased intrauterine growth (r = 0.446, p < 0.01). Moreover, twinning increased oxidative stress in cord blood (p < 0.05), which might also contribute to fetal growth restriction. These results reinforce the importance of maternal nutrition, especially for those ewes bearing multiples, and opens new possibilities for nutritional or antioxidant interventions for preventing fetal hypoxia and oxidative stress.