Domestic animal endocrinology最新文献

This paper reviews the role of endocrine regulators in swine ovarian cell functions, highlighting the intricate hormonal interactions that drive reproductive and metabolic processes. The pig represents a valuable model for human biology due to physiological and anatomical similarities. Understanding the endocrine mechanisms in swine can provide insights about human reproductive health and metabolic disorders. The present review describes some key hormones involved, including gonadotropins, sex steroids, and adipokines, and their impacts on ovarian folliculogenesis and steroidogenesis. Emphasis is placed on the crosstalk between the ovary and adipose tissue, which is critical for maintaining reproductive and metabolic homeostasis.

Intrauterine growth restriction (IUGR) is a common condition in swine associated with high piglet mortality and morbidity that develops in early gestation. This review article explores differences in uterine and placental tissues associated with IUGR fetuses compared to their normally-grown littermates at different stages of gestation. Specifically, we will review the available knowledge to date describing differences in 1) structure, 2) cellular apoptosis and proliferation, 3) adhesion, and 4) angiogenesis in endometrial and placental tissues associated with IUGR fetuses across gestation. Improved understanding of the mechanisms regulating IUGR is essential for the development of strategies to minimize the impact of IUGR in swine operations, thus improving reproductive efficiency and animal welfare.

This review presents recent findings on the effect of melatonin on ram spermatozoa. This hormone regulates seasonal reproduction in the ovine species through the hypothalamic-pituitary-gonadal axis, but it also exerts direct effects on spermatogenesis, seminal quality and fertility. In the testis, melatonin stimulates blood flow to this organ, but it also appears to be involved in the differentiation of spermatogonial stem cells and the secretion of testosterone through the MT1 and MT2 receptors. In the epididymis, this hormone modulates sperm maturation and the secretory activity of epidydimal epithelial cells. In addition, the antioxidant activity of melatonin may protect spermatozoa from oxidative damage during their formation in the testis and their maturation in the epididymis. After ejaculation, the melatonin present in seminal plasma may also protect sperm from oxidative damage and premature capacitation and may improve seminal quality. Finally, once the sperm begins its transit through the female genital tract, melatonin may modulate sperm capacitation. Thus, melatonin could have a bimodal activity in ram sperm capacitation, so high concentrations, such as those in seminal plasma, have a decapacitating effect. In contrast, low concentrations, such as those present in the female reproductive tract, may promote it, likely through interaction with MT2 receptors. In addition, melatonin could also be involved in chemotaxis and fertilisation, although further studies are needed to elucidate the specific role of melatonin in these processes. Finally, the effect of latitude and melatonin receptor gene polymorphisms in ram reproduction is also discussed.

Canine diabetes mellitus (DM) is associated with hyperglycemia and hyperlipidemia. Visfatin and betatrophin are adipokines involved in the pathophysiology of insulin resistance and deranged lipid metabolism, and are also altered in obesity. We hypothesized that visfatin and betatrophin serum concentrations are altered in diabetic dogs, irrespective of their body condition. The study included 23 newly-diagnosed DM (NDDM) dogs, 34 insulin-treated DM (ITDM) dogs and 24 healthy dogs. Body condition score was determined and fasted serum samples were collected for measurement of betatrophin, visfatin and insulin serum concentrations. Visfatin concentrations (mean, 95% CI) were lower in overweight NDDM (4.5 ng/mL, 2.5-8.1, P=0.05) and ITDM (2.8 ng/mL 1.8-4.3, P=0.006) than healthy (7.7 ng/mL, 5.0-11.7) dogs, but were not different among lean dogs, and were negatively correlated to betahydroxybutyric acid in ITDM dogs (r=-0.59, P=0.05). Betatrophin concentrations were lower in NDDM (69 pg/mL, 43-112, P<0.001) and ITDM (53 pg/mL, 34-84, P<0.001) than healthy (267 pg/mL, 167-426) dogs. Among NDDM dogs, betatrophin concentrations were higher in those with concurrent liver disease (203 pg/mL, 49-844) than those with no evidence of liver disease (19 pg/mL, 4-90, P=0.007), and were negatively correlated with glucose concentrations (r=-0.44, P=0.04) and creatinine (r=-0.60, P=0.003). Insulin concentrations were not different among NDDM and healthy dogs. Among NDDM dogs, insulin concentrations were negatively correlated to concentrations of betahydroxybutyric acid (r=-0.65, P=0.002) and were lower in dogs with concurrent kidney disease (5.6 mU/L, 2.1-15.3) compared to those with no evidence of kidney disease (20.6 mU/L, 8.0-53.2, P=0.018). In conclusion, DM in dogs is associated with alteration in visfatin and betatrophin concentrations that are not resolved by insulin treatment.

The scientific discipline of endocrinology has been invaluable to our understanding of the estrous cycle. In the second half of the twentieth century the development of immunoassay technologies provided a rapid and sensitive method to quantify circulating concentrations of reproductive hormones and relate them to stage of the estrous cycle and physiological status of the animal. Ovarian ultrasonography provided the ability to track the growth and regression of ovarian structures within the same animal across the estrous cycle in real time and, in combination with hormonal profiling, accurately identify mechanisms regulating the estrous cycle and early pregnancy. Before this, the best technique had been serial collections with each animal being a single endpoint. The availability of continuous data such as daily hormone concentrations and daily follicular measurements within animals led to the improvement of methods to synchronize estrus in each of the species. Unfortunately, the use of radio-immunoassays has been declining for two decades. While enzyme-linked immunosorbent assays have been developed for many endocrine, paracrine, and autocrine factors, their primary market is human medicine and rodent models of human health, leaving those available for livestock species economically infeasible. Automated sensors such as accelerometers apply the knowledge attained through decades of endocrinology and ultrasonography studies to identify females in estrus and measure parameters of the estrous cycle that are related to fertility. The ability of automated sensors to centralize and assimilate large amounts of behavioral and physiological data from numerous animals will enhance targeted reproductive management in livestock production systems.

This study aimed to evaluate the ovulatory response to GnRH treatment based on the day of its administration in the first follicular wave of the estrous cycle in goats. We hypothesized that maximum ovulatory response with GnRH treatment is dependent on the day of its administration during the early luteal phase of estrous cycle. Forty-eight goats were presynchronized with a single dose of PGF_2α, and ultrasonography was performed to confirm ovulation (Day 0). Following ovulation, goats (n = 38) were randomly assigned to receive GnRH treatment on Days 2, 4, 6, or 8 of the estrous cycle. Follicular dynamics were assessed every 4 h after GnRH treatment and 37% of goats ovulated within 12.0 ± 1.5 h after treatment. Ovulation rate was significantly higher on Day 4 compared to Day 2 (P = 0.03) and gradually declined by Day 8. Goats with dominant follicles with diameters between 6.1 and 7.0 mm had significantly higher ovulation rate than goats < 6.1 mm (P = 0.01). A strong negative correlation was found between dominant follicle diameter at the time of GnRH administration and anovulation (r_pb = -0.79). The growth rate of dominant follicles after GnRH administration remained higher in Day 4 than Day 8 (P < 0.05). Similarly, the interval to new follicular wave emergence was longer on Day 4 than on Days 2, 6 and 8 (P < 0.05). In conclusion, administering GnRH on Day 4 of the estrous cycle yielded the highest ovulatory response, particularly when the dominant follicle measured between 6.1-7.0 mm during the first follicular wave of estrous cycle.

This review describes various aspects of the leptin resistance phenomenon and related physiological mechanisms that occur in pregnant sheep. Its main aim is to analyze the mechanisms that determine the occurrence of pregnancy-induced leptin resistance and to investigate the accompanying processes that affect the physiology of pregnancy and lactation in livestock. The main purpose of this analysis was to comprehensively understand the phenomenon of leptin resistance, including the causes of its emergence and its effects on nonrodent organisms.

Energy supply is crucial for testicular development. Nevertheless, the specific alterations in the energy metabolic pathways that affect testicular development have not been extensively investigated. This study aimed to investigate the variations in metabolites and alterations in energy metabolic pathways in the testes of Hu sheep with different developmental status at 6 months of age. Twelve rams with similar body weights but distinct testis developmental status were selected among 345 Hu sheep based on testis size and histomorphology results, and they were divided into the well-developed (L group, n = 6) and developmentally delayed group (S group, n = 6). A total of 660 metabolites were identified via widely targeted metabolic analysis. Among 148 differentially expressed metabolites, 78 were up-regulated and 70 were downregulated in the L group compared with the S group. Functional enrichment analysis indicated that a significant proportion of the identified differential metabolites was implicated in energy metabolism-related pathways. Moreover, the L group exhibited significantly higher expression levels of genes involved in glycolysis (GLTU8 and LDH), TCA (PDHA2, CS and IDH3G), gluconeogenesis (PCK1), pentose phosphate (G6PD), and fatty acid degradation (GK, ACSL1, FABP3, CPT1 and CTP2). The activity enzymes such as citrate synthase, pyruvate dehydrogenase, and lactate dehydrogenase also increased in the L group. In summary, this observation implied that the augmentation of energy metabolic pathways plays a crucial role in facilitating testicular development. The upregulation of energy metabolic pathways collectively facilitates the testicular development in Hu sheep.

Gonadotropin-releasing hormone (GnRH) vaccines have been widely used to effectively inhibit gonadal development and reproductive function. To improve the immunogenicity of GnRH, we developed and evaluated the effects of GnRH6-kisspeptin-CRM197 immunization on the reproductive function in male goats. Thirty 3-month-old male goats (n = 30) were randomly assigned to control, surgical, and immunized groups. The immunized group received a 2 mL injection of the GnRH6-kisspeptin-CRM197 with a booster administered four weeks later. The control group was administered a white oil adjuvant. Blood samples were collected at regular intervals, and at week 20, the animals were euthanized for tissue collection. Serum antibody titers and testosterone levels were measured using ELISA and CLIA, respectively. Testicular parameters and histology were evaluated. The mRNA levels of reproductive-related genes in the HPG axis were measured using RT-qPCR. The results showed that the immunized goats had significantly increased serum GnRH and kisspeptin antibodies (P < 0.05) but decreased testosterone concentrations (P < 0.05) compared to the control group. Testicular size and histology were significantly affected in the immunized group, with notable reductions in testicular weight and dimensions (P < 0.01), and evidence of vacuolar degeneration and suppressed sperm production. The mRNA levels of FSHβ and LHβ in the pituitary, as well as FSHR, LHR, 3βHSD, and 17βHSD in the testis, were significantly lower in the immunized group compared to controls (P < 0.05). These findings suggest that GnRH6-kisspeptin-CRM197 is a safe antigen and a promising immunocastration vaccine with enhanced efficacy.

Disturbances in maternal nutrient availability through increased or decreased abundance of specific or total nutrients during pre-natal development can have negative impacts on offspring growth. These changes are likely mediated, at least in part, by hormonal systems that control energy homeostasis and appetite. Regulation of insulin signaling is critical to ensuring appropriate glucose homeostasis. Poor maternal nutrition during gestation impacts circulating glucose and insulin concentration in both the dam and offspring, reducing circulating insulin and glucose in offspring of restricted-fed dams and increased circulating insulin and glucose in the offspring of over-fed dams. Leptin and ghrelin are key regulators of appetite and feed intake. Offspring of over-fed ewes often exhibit leptin resistance, which may lead to changes in adiposity. Leptin responses in offspring of restricted-fed ewes are not well defined, although restricted-fed ewes themselves exhibit decreased circulating leptin concentrations. Little is known about the effects of poor maternal nutrition on offspring ghrelin. Glucocorticoids and thyroid hormones are required for appropriate fetal development. Poor maternal nutrition during gestation alters the development of the hypothalamic-pituitary-adrenal and thyroid axes in the offspring, although the effects vary according to the type, duration, timing, and severity of the nutritional insult. The relationships between insulin, leptin, ghrelin, glucocorticoids, and thyroid hormones can result in synergistic effects, exacerbating negative outcomes for the offspring. The impacts of poor maternal nutrition are multi-faceted, and the resulting alterations in body composition can continue to impact hormone regulation beyond the initial insult caused by poor maternal nutrition during gestation.