Endocrinology of reproductive function and pregnancy at high altitudes

6 Pág.Reproductive function and therefore fertility, both in women and men, are affected by the high altitude environment. Hypobaric hypoxia affects functionality of the hypothalamus–hypophysis–gonads axis, sperm quality, cyclic ovulatory activity, and quality of preovulatory follicles, oocytes, corpora lutea, and embryos. Hence, chances for obtaining pregnancy are diminished in humans and animals living at high altitudes. The occurrence of intrauterine growth restriction is around 3-fold higher than that at low altitude. Most of these deficiencies are related not only to hypoxia but also to increased oxidative stress. Hence, supplementation with antioxidant agents may constitute a useful strategy.This work was supported by Projects Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT) 1020706, 1070405, 1100189, and 1130181 from Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Project DID- ENL 06/2 from Universidad de Chile; Projects Agencia Española de Cooperación Internacional para el Desarrollo (AECID) A/023494/09 and A/030536/10) from the Spain Government.Peer reviewe

Effect of time of artificial insemination after estrus detection on Corriedale sheep pregnancy rates

A total of 240 adult Corriedale ewes from the Magallanes Region of Chile, were synchronized with progestagens and randomly assigned to one of four groups, according to the time elapsed between estrus detection and artificial insemination (AI) with semen obtained from 2 Corriedale rams. The first three groups were inseminated at 3 and 6; 6 and 12; or 12 and 18 h after estrous detection; the fourth group received a single insemination 18 h after estrous detection. Semen was extracted and frozen in a solution of skimmed milk, glycerol and egg yolk, thawed and used, registering the depth of semen placement in the cervix and the quantity and nature of the cervical mucosa. Pregnancy was assessed by ultrasound 30 days after insemination. No significant statistical differences were detected among pregnancy rates, which were 22; 31; 22; and 21% for groups 1; 2; 3 and 4, respectively. Nor were there significant differences with one or two inseminations. Results showed that fertility did not differ when insemination was performed 3 to 18 h after estrous detection, and that double insemination is not necessary, as long as insemination coincides with the middle of the estrous period

Efecto del Tiempo de Inseminaci\uf3n Artificial Despu\ue9s de la Detecci\uf3n de Celo Sobre la Tasa de Pre\uf1ez en Ovinos Corriedale

A total of 240 adult Corriedale ewes from the Magallanes Region of Chile, were synchronized with progestagens and randomly assigned to one of four groups, according to the time elapsed between estrus detection and artificial insemination (AI) with semen obtained from 2 Corriedale rams. The first three groups were inseminated at 3 and 6; 6 and 12; or 12 and 18 h after estrous detection; the fourth group received a single insemination 18 h after estrous detection. Semen was extracted and frozen in a solution of skimmed milk, glycerol and egg yolk, thawed and used, registering the depth of semen placement in the cervix and the quantity and nature of the cervical mucosa. Pregnancy was assessed by ultrasound 30 days after insemination. No significant statistical differences were detected among pregnancy rates, which were 22; 31; 22; and 21% for groups 1; 2; 3 and 4, respectively. Nor were there significant differences with one or two inseminations. Results showed that fertility did not differ when insemination was performed 3 to 18 h after estrous detection, and that double insemination is not necessary, as long as insemination coincides with the middle of the estrous period.Un total de 240 ovejas Corriedale fueron sincronizadas con progesterona y asignadas al azar a 4 grupos, seg\ufan el tiempo transcurrido entre la detecci\uf3n de celo y la inseminaci\uf3n artificial (IA) con semen de carneros de la misma raza. Los primeros 3 grupos fueron inseminados luego de 3 y 6, 6 y 12; \uf3 12 y 18 h de detectado el celo; el cuarto grupo recibi\uf3 una sola inseminaci\uf3n 18 h despu\ue9s de detectado el celo. El semen fue extra\ueddo y congelado en una soluci\uf3n de leche descremada, glicerol y yema de huevo, descongelado y usado, registr\ue1ndose la profundidad de depositaci\uf3n del semen en el c\ue9rvix y la cantidad y naturaleza de la mucosa cervical. Treinta d\uedas despu\ue9s se determin\uf3 la pre\uf1ez mediante ecograf\ueda. No se detectaron diferencias estad\uedsticamente significativas entre los porcentajes de pre\uf1ez, que fueron de 22; 31; 22; y 21%, para los grupos 1, 2, 3 y 4, respectivamente. Tampoco fueron significativas las diferencias en fertilidad con una o dos inseminaciones

Empowering translational research in fetal growth restriction Sheep and swine animal models

Fetal or intrauterine growth restriction (FGR or IUGR) is a concerning health issue not only due to its implications in mortality and morbidity of neonates but also because of its long-term consequences on health and disease risk of the individuals. Its main cause is an insufficient supply of nutrients and oxygen by maternal (malnutrition or hypobaric hypoxia) or placental factors (placental insufficiency) during late gestation, when the requirements of fetus are higher. The availability of reliable animal models would be highly useful for the future development of diagnostic, preventive and therapeutic strategies. Most of the studies using animal models have been performed in rodents, while the use of large animals (sheep and swine) has been scarce. The objective of the current review is to offer an overview on the possibilities of using large animals for conducting translational research on IUGR related to inadequate maternal conditions and/or placental dysfunction. © 2016 Bentham Science Publishers

Steroidogenesis in sheep pregnancy with intrauterine growth retardation by high-altitude hypoxia Effects of maternal altitudinal status and antioxidant treatment

Sheep pregnancy in high-altitude environments frequently involves hypoxia and oxidative stress and causes intrauterine growth retardation. The adverse effects of altitude on fetal growth can be prevented by the administration of antioxidant vitamins, but the mechanisms responsible are not well known. The maintenance of a viable pregnancy depends largely on adequate placental steroidogenesis, especially in the last two-thirds of pregnancy. Thus, in the present study we evaluated the effect of antioxidant vitamins (C and E) on plasma concentrations of progesterone and 17β-oestradiol during the last two-thirds of high-altitude pregnancies in ewes both native and naïve to the high-altitude environment. In addition, pregnancy outcomes were evaluated by determining the bodyweight of newborn lambs. Sex steroid patterns differed between ewes with and without vitamin supplementation. Concentrations of plasma progesterone and 17β-oestradiol were significantly higher in the supplemented groups from approximately 40 days before parturition until near term. Newborn weights were significantly lower in animals not adapted to the higher altitude, and vitamin supplementation prevented this decrease. In conclusion, the administration of antioxidant vitamins in the present study enhanced placental steroidogenesis, thus favouring fetal development in pregnancies developing at high altitudes. © 2013 CSIRO

In vitro fertilization and development of cumulus oocytes complexes collected by ultrasound-guided follicle aspiration in superstimulated llamas

The objective was to evaluate the developmental competence of cumulus-oocyte complexes (COC) collected by follicular aspiration in llamas treated with FSH or eCG. Llamas were assigned randomly to two groups (n = 16 per group) and treated, at the time of ovarian follicular wave emergence, with either: 1) 25 mg of FSH im, twice daily for 4 d; or 2) 1000 IU of eCG as a single i.m. dose. The start of gonadotropin treatment was considered Day 0. Both groups were given 5 mg of Armour Standard LH im on Day 6, and COC were collected by follicle aspiration on Day 7. Expanded COC collected from FSH- (n = 157) and eCG-treated llamas (n = 151) were fertilized in vitro using epididymal sperm, and presumptive zygotes were in vitro cultured in SOF medium for 8 d. The FSH and eCG treatment groups did not differ with respect to: the number of follicles >= 7 mm (16.0 +/- 2.7 vs 14.0 +/- 1.9, respectively; P = 0.5); the number of COC collected (11.5 +/- 1.9 vs 9.7 +/- 1.2; P = 0.4); the number of expanded COC (9.8 +/- 1.4 vs 9.4 +/- 1.2; P = 0.8); or the percentage of presumptive zygotes which developed into 2 to 8 cell stage embryos (65.3 vs 63.1), morulas (46.2 vs 42.5), or blastocysts (23.1 vs 20.5; P > 0.05). In conclusion, FSH and eCG treatments were equally effective for recovery of a high number of expanded COC which were used directly for in vitro fertilization. Furthermore, rate of embryo development was not significantly affected by the gonadotropin treatment used. (C) 2011 Elsevier Inc. All rights reserved

Hypoxia and oxidative stress are associated with reduced fetal growth in twin and undernourished sheep pregnancies

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. 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