Age at First Gestation in Beef Heifers Affects Fetal and Postnatal Growth, Glucose Metabolism and IGF1 Concentration.

This study aimed to determine the effects of age at first gestation on offspring growth performance, glucose metabolism, and IGF1 concentration. Heifers impregnated by AI from a single bull at 15 months of age (15 M, n = 20), or 27 months of age (27 M, n = 20), and multiparous cows (adult, n = 20) were used. Dams from all groups were managed in a single group during gestation and lactation. Gestational length was longer in the 15 M and 27 M than in adult dams (p = 0.009). Bodyweight at birth, at weaning and ADG during lactation were higher in calves from adult dams than in those from 27 M dams, and higher in calves from the latter than in 15 M calves (p < 0.001). Calves from 15 M dams had an increased head circumference/BW ratio compared to calves from 27 M dams, while calves from this latter group had an increased ratio compared to calves from adults (p = 0.005). Body mass index was greater in calves from adults than in those from 15 M and 27 M dams (p = 0.002). Milk production from 15 M and 27 M dams was similar but lower than that from adults (p = 0.03). Calves born from adult dams had greater blood glucose concentrations than those from 15 M and 27 M dams (p < 0.05). Serum IGF1 concentrations were higher in calves from adults than in calves from 15 M and 27 M dams (p = 0.01). This study showed that age at first gestation affects offspring postnatal growth performance, glucose metabolism and IGF1 concentration.

Corrigendum to "Angiogenesis in Pituitary Adenomas: Human Studies and New Mutant Mouse Models".

[This corrects the article DOI: 10.1155/2014/608497.].

The Notch system during pubertal development of the bovine mammary gland.

The development of the mammary gland of cows during pre-weaning and puberty will condition its future productive capacity and warrants special study. In this respect, Notch signaling regulates tissue development and fate by modifying cell proliferation and differentiation and has been involved in stem cell maintenance, but has not been extensively studied in the developing mammary glands in cows. We therefore investigated Notch receptor expression and localization, as well as the expression of Notch ligands and target genes in the mammary gland of Holstein heifers in pre- and post-pubertal stages. Notch receptors 1 to 4 were detected by immunohistochemistry in the parenchyma and stroma of the developing gland. The subcellular localization of the four receptors was predominantly cytoplasmic except for NOTCH4, which was mostly nuclear. The membrane and the active intracellular domains of NOTCH paralogues were identified by western blot. NOTCH1 and NOTCH2 active domains increased during pubertal stages while NOTCH3 and NOTCH4 active domains decreased, suggesting strikingly different involvement of NOTCH paralogues in bovine mammary gland development and differentiation. The mRNA expression levels of the target genes HEY1 and HEY2 increased during peri-puberty whereas no variation of HES1 mRNA levels was observed. The mRNA levels of the Notch ligands JAGGED1 and DELTA1 also increased gradually during development. In conclusion, Notch signaling system dynamically varies throughout the development of the mammary gland during puberty pointing to specific time involvement of each component.

Angiogenesis in pituitary adenomas: human studies and new mutant mouse models.

The role of angiogenesis in pituitary tumor development has been questioned, as pituitary tumors have been usually found to be less vascularized than the normal pituitary tissue. Nevertheless, a significantly higher degree of vasculature has been shown in invasive or macropituitary prolactinomas when compared to noninvasive and microprolactinomas. Many growth factors and their receptors are involved in pituitary tumor development. For example, VEGF, FGF-2, FGFR1, and PTTG, which give a particular vascular phenotype, are modified in human and experimental pituitary adenomas of different histotypes. In particular, vascular endothelial growth factor, VEGF, the central mediator of angiogenesis in endocrine glands, was encountered in experimental and human pituitary tumors at different levels of expression and, in particular, was higher in dopamine agonist resistant prolactinomas. Furthermore, several anti-VEGF techniques lowered tumor burden in human and experimental pituitary adenomas. Therefore, even though the role of angiogenesis in pituitary adenomas is contentious, VEGF, making permeable pituitary endothelia, might contribute to adequate temporal vascular supply and mechanisms other than endothelial cell proliferation. The study of angiogenic factor expression in aggressive prolactinomas with resistance to dopamine agonists will yield important data in the search of therapeutical alternatives.

Gastrointestinal parasite control during prepuberty improves mammary parenchyma development in Holstein heifers.

Parasitism during development impairs normal growth and delays the onset of puberty through altered hormone profiles, including insulin-like growth factor one (IGF-1). As mammary gland development during prepuberty is strongly dependent on IGF-1, we determined if antiparasitic treatment during this stage of growth improved mammary gland development. One group of Holstein heifers was treated monthly, rotationally with antiparasitic drugs from birth to 70 weeks of age, a second group was untreated. Treated heifer calves had between 56% and 65% less EPG counts than untreated ones. Presence of Ostertagia, Cooperia, Haemonchus and Trichostrongylus was demonstrated. Treatment effectively advanced the onset of puberty and increased IGF-1 levels. At 20, 30, 40 and 70 weeks of age biopsies from the mammary gland were taken and histological sections were prepared and stained with hematoxylin-eosin. Pictures were analyzed to compare parenchyma area in relation to total mammary tissue between groups. Mammary samples from treated heifers had higher ratios of parenchyma/total area than untreated ones. As mammary development during prepuberty is crucial for mammary performance during lactation, these results add new evidence to the importance of gastrointestinal parasite control in heifers.

Effect of fat supplementation on leptin, insulin-like growth factor I, growth hormone, and insulin in cattle.

We investigated the effect of fat supplementation on plasma levels of hormones related to metabolism, with special attention to leptin, in cows in early lactation and in feedlot steers. In experiment 1, 34 lactating cows received no fat or else 0.5 or 1.0 kg of partially hydrogenated oil per day in addition to their basal diet from day 20 before the expected calving date to day 70 postpartum. In experiment 2, part of the corn in the basal concentrate was replaced with 0.7 kg of the same oil such that the diets were isocaloric; 18 cows received the fat-substituted diet and 18 a control diet from day 20 before the expected calving date to day 75 postpartum. In experiment 3, calcium salts of fatty acids were added to the basal diet of 14 feedlot steers for 80 d; another 14 steers received a control diet. The basal plasma levels of leptin were higher in the cows than in the steers. Dietary fat supplementation did not affect the leptin levels in the lactating cows but lowered the levels in the feedlot steers despite greater energy intake and body fatness (body weight) in the steers receiving the supplement than in those receiving the control diet. The levels of insulin-like growth factor I and insulin were decreased with dietary fat supplementation in the lactating cows but were unaffected in the steers, suggesting that responses to fat ingestion depend on the physiological state of the animal, including age and sex. Finally, no effects of supplementary fat on the level of growth hormone were demonstrated in any of the models.

Control hormonal del desarrollo puberal en la rata hembra / Endocrine control of pubertal development in the female rat

La rata hembra resulta un interesante modelo experimental para estudiar el desarrollo del control de las hormonas hipofisarias involucradas en la reproducción. Desde el nacimiento hasta la eclosión puberal transcurren aproximadamente 36 días que pueden ser divididos en 4 etapas: a) neonatal, hasta el día 7 de vida, b) infantil, de 7 a 21, c) juvenil, 21 a 30 días, y d) peripuberal, período que culmina con la primera ovulación. Durante estas etapas los perfiles hormonales son definidos y sujetos a un control característico para cada período. La prolactina está baja hasta el fin del período infantil, momento en que comienza a aumentar gradualmente. Este aumento está relacionado con una maduración de mecanismos liberadores de la prolactina (como el sistema serotoninérgico y el estradiol), en presencia de un aumento del tono dopaminérgico inhibitorio. La prolactina en aumento produce una maduración de los receptores ováricos a LH, y una desensibilización de receptores dopaminérgicos, ambos eventos importantes para la eclosión puberal. La FSH aumenta desde el nacimiento hasta alcanzar el día 12 de vida valores máximos. Luego desciende permaneciendo baja hasta la pubertad. Las causas de este perfil de secreción son múltiples: a los 12 días de edad hay una aumentada sensibilidad de la hipófisis a la LHRH, y una mayor liberación de FSH por serotonina. Por otro lado, frente a una escasa retroalimentación negativa estrogénica y bajos niveles de inhibina, la FSH está bajo control negativo de la... (AU)

Control hormonal del desarrollo puberal en la rata hembra / Endocrine control of pubertal development in the female rat

La rata hembra resulta un interesante modelo experimental para estudiar el desarrollo del control de las hormonas hipofisarias involucradas en la reproducción. Desde el nacimiento hasta la eclosión puberal transcurren aproximadamente 36 días que pueden ser divididos en 4 etapas: a) neonatal, hasta el día 7 de vida, b) infantil, de 7 a 21, c) juvenil, 21 a 30 días, y d) peripuberal, período que culmina con la primera ovulación. Durante estas etapas los perfiles hormonales son definidos y sujetos a un control característico para cada período. La prolactina está baja hasta el fin del período infantil, momento en que comienza a aumentar gradualmente. Este aumento está relacionado con una maduración de mecanismos liberadores de la prolactina (como el sistema serotoninérgico y el estradiol), en presencia de un aumento del tono dopaminérgico inhibitorio. La prolactina en aumento produce una maduración de los receptores ováricos a LH, y una desensibilización de receptores dopaminérgicos, ambos eventos importantes para la eclosión puberal. La FSH aumenta desde el nacimiento hasta alcanzar el día 12 de vida valores máximos. Luego desciende permaneciendo baja hasta la pubertad. Las causas de este perfil de secreción son múltiples: a los 12 días de edad hay una aumentada sensibilidad de la hipófisis a la LHRH, y una mayor liberación de FSH por serotonina. Por otro lado, frente a una escasa retroalimentación negativa estrogénica y bajos niveles de inhibina, la FSH está bajo control negativo de la...