A variety of ion channels are expressed in the plasma membrane of somatotropes within the anterior pituitary gland. Modification of these channels is linked to intracellular Ca2+ levels and therefore to hormone secretion. Previous investigations have shown that the gut-derived orexigenic peptide hormone ghrelin and synthetic GH-releasing peptides (GHRPs) stimulate release of growth hormone (GH) and increase the number of functional voltage-gated Ca2+ and Na+ channels in the membrane of clonal GC somatotropes. Here, we reveal that chronic treatment with ghrelin and its synthetic analog GHRP-6 also increases GH release from bovine pituitary somatotropes in culture, and that this action is associated with a significant increase in Na+ macroscopic current. Consistent with this, Na+ current blockade with tetrodotoxin (TTX) abolished the ghrelin- and GHRP-6-induced increase in GH release. Furthermore, semi-quantitative and real-time RT-PCR analysis revealed an upregulation in the transcript levels of GH, as well as of NaV1.1 and NaV1.2, two isoforms of TTX-sensitive Na+ channels expressed in somatotropes, after treatment with ghrelin or GHRP-6. These findings improve our knowledge on (i) the cellular mechanisms involved in the control of GH secretion, (ii) the molecular diversity of Na+ channels in pituitary somatotropes, and (iii) the regulation of GH and Na+ channel gene expression by ghrelin and GHRPs.
Objetivo. Caracterizar el sistema de producción bovino doble propósito (SPDP) en unidades de producción pecuaria (UPP) de municipios de la Huasteca Alta Veracruzana (HAV) y determinar la tipología de las UPP dentro del SPDP. Materiales y métodos. Con variables sociales (productor), cuantitativas del hato e índices tecnológicos, agrupados en áreas zootécnicas (Reproducción, Salud, Nutrición, Pastos y Administrativa) se analizó la información de 135 UPP del SPDP recabada a través de encuestas y visitas in situ, con registros de sus actividades sociales, económicas y pecuarias; asi mismo, se analizó el panorama climatológico con información de estaciones meteorológicas de la región. Se utilizó el análisis multivariados K-means y Conglomerado (Statistica V10); con ello, se logró identificar cinco grupos de UPP catalogándose como: Empresarial (n= 4), Transición (n= 29), Tradicional Alto (n=34), Medio (n= 37) y Bajo (n= 31). Con ANDEVA de una vía fueron analizadas las variables socioeconómicas, productivas y propias del hato. Resultados. Las UPP Empresarial y Transición se diferenciaron (p < 0.05) de las de tipo Tradicional por poseer una mayor superficie (hectáreas) utilizada para la ganadería, número de vacas y mayores índices tecnológicos de salud, nutrición y económico (p< 0.05), características que describen la obtención de mayores ingresos por venta la de leche y becerros para la engorda. Conclusiones. El índice tecnológico del SPDP es de 0.37 ± 0.01 a 0.61 ± 0.06 (bajo-medio), esta situación y las condiciones climatológicas actuales afectan su productividad.
Objective: To correlate the Breeding Soundness Evaluation (BSE) of Charolais andCharbray bulls in the warm subhumid climate and its effect on the Pregnancy rate andCalving interval of herds to estimate differences between breeds.Design/methodology/approach: BSE was carried out on N = 90 Bulls; Charolais (n =33) and Charbray (n = 57), evaluated in situ during the period 2017 to 2019. Bull (age, body condition, libido, and scrotal circumference), Semen (concentration, motility, and volume), Herd (Pregnancy rate and Calving interval) and environment variables (Rainy and Dry season) were analyzed with the one-way ANOVA, Factorial, Multiple regression, and Multivariate analysis.Results: Charolais and Charbray bulls show similar results in the BSE (p>0.05) in awarm subhumid climate.Limitations/implications: Year season (Rainy or Dry) do not affect (p<0.05) the BSErating. Libido is associated (p<0.05) with age (R=-0.42), sperm motility (R=0.67), spermconcentration (R=0.66) and pregnancy rate (R=0.63).
Findings/conclusions: Variables with high association (p<0.05) with pregnancy ratewere libido (R=0.63), motility (R=0.60), sperm concentration (R=0.51) and age (R=-0.50); variables with high association (p<0.05) with calving interval were: age (R=0.74)and libido (R=-0.33). Charolais and Charbray bulls show similar reproductive efficiencyin herds under a warm subhumid climate in Veracruz.
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