Domestic animal endocrinology最新文献

Cold exposure is a common stressor for newborn goats. Skeletal muscle plays an important role in maintaining whole-body homeostasis of glucose and lipid metabolism. However, the molecular mechanisms underlying regulation of skeletal muscle of newborn goats by cold exposure remains unclear. In this study, we found a significant increase (P < 0.01) in serum glucagon levels after 24 h of cold exposure (COLD, 6°C), while glucose and insulin concentrations were significantly decreased (P < 0.01) compared to room temperature (RT, 25°C). Additionally, we found that cold exposure reduced glycogen content (P < 0.01) in skeletal muscle. Pathway enrichment analysis revealed that cold exposure activated skeletal muscle glucose metabolism pathways (including insulin resistance and the insulin signaling pathway) and mitophagy-related pathways. Cold exposure up-regulated the expression of genes involved in fatty acid and triglyceride synthesis, promoting skeletal muscle lipid deposition. Notably, cold exposure induced mitophagy in skeletal muscle.

The oviduct, the organ of the female reproductive system where fertilization and early embryonic development occur, provides an optimal environment for the final maturation of oocytes, storage, and sperm capacitation and transport of gametes and embryos. During the estrous cycle, the oviduct is affected by ovarian sex hormones, resulting in changes aimed at maintaining an appropriate microenvironment. Normal cell migration is tightly regulated, its role being essential for the development and maintenance of organ and tissue functions as well as for regeneration following injury. Due to their involvement in focal contact formations, focal adhesion kinase (PTK2) and paxillin (PXN) are key proteins in the study of cell migration and adhesion. The objective of this work was to compare the expression of PTK2 and PXN in oviductal cells along the estrous cycle and to determine if their expression is regulated by the presence of 17-β estradiol (E₂) and/or progesterone (P₄). No transcripts of PTK2 or of PXN were detected in cells corresponding to the luteal phase. Additionally, hormonal stimulation experiments on bovine oviductal cell cultures (BOECs) were carried out, where P₄ inhibited the expression of both genes. Migration assays demonstrated that P₄ reduced BOECs migration capacity. P₄ treatment also reduced cell adhesion, while E₂ increased the number of adhered cells. In conclusion, the presence of E₂ and P₄ regulates the expression of genes involved in the formation of focal contacts and modifies the migration and adhesion of BOECs. Understanding the effect of steroid hormones on BOECs is critical to grasp the impact of steroid control on oviductal function and its contribution to establishing successful pregnancies.

Increased fetal cortisol is associated with catecholamine release, a primary factor for neonatal adaptive responses. However, relationship between canine peripartum cortisol and catecholamine is unknown. We aimed to compare serum adrenaline, noradrenaline and cortisol during peripartum in bitches and neonates of distinct obstetric conditions and to assess amniotic fluid cortisol concentration. Twenty females and maximum of three puppies per litter were allocated into Vaginal Eutocia (10 females; 17 neonates) and Elective C-section (10 females; 20 neonates) groups. Amniotic fluid was collected at delivery for cortisol concentration. Maternal and neonatal blood were collected prepartum, intrapartum, postpartum and 1h postpartum, and at birth, 30 and 60min, 12hs and 24hs, respectively, for cortisol, adrenaline and noradrenaline assessment. C-section determined higher noradrenaline throughout delivery and cortisol concentration from intrapartum through 1h postpartum, compared to vaginal birth. C-section maternal cortisol showed progressive increase from intrapartum onwards, while neonatal cortisol remained unchanged. No difference of maternal cortisol concentration occurred along whelping, whereas a significant decrease was verified for vaginal delivery puppies from birth until the 12hs. Puppies delivered vaginally had higher cortisol concentration at birth and 30min, compared to c-section puppies. There was a higher concentration of amniotic fluid cortisol in vaginal eutocia. In conclusion, c-section induces higher maternal stress during and after surgery, whilst vaginal delivery is a more neonatal physiologically stressful condition, contributing to better adaptation during transition.

The aim of this study was to determine if intranasal administration of oxytocin modifies sexual behaviour and the stress response in young rams during sexual tests with ewes in oestrus. Ten rams were used in a cross-over design. At Day 0, the control group (CG, n = 5) received isotonic saline spray intranasally, and the treated group (OTG, n = 5) received oxytocin (24 IU) intranasally, 40 min before the sexual test. At Day 15, the groups were reversed. In each sexual test (20 min) with an oestrous-induced ewe, the sexual behaviour of the young rams was recorded. Serum cortisol concentrations were determined before and after the test. Less flehmen was observed in the OTG, but mounts with ejaculation were increased. The OTG presented lower serum cortisol concentration than the CG. In conclusion, intranasal administration of oxytocin modified the sexual behaviour of rams, evidenced by a decrease in flehmen behaviour and an increase in mounts with ejaculation, making sexual activity more efficacious. In addition, the treatment decreased the stress response of the rams in the sexual tests. Therefore, intranasal administration of oxytocin could be used to increase sexual activity in rams, and with less stress, providing better welfare conditions.

Feline diabetes mellitus is a common endocrine disease with increasing prevalence. It shows similarities with human type 2 diabetes and is characterized by insulin resistance and deficient insulin secretion. Moreover, cats and humans belong to the very few species that form amyloid depositions in the pancreatic islets. However, little is known about cat islet function and no studies have addressed insulin secretion from isolated islets ex vivo. The aim of this study was to establish a protocol for isolation of islets of Langerhans from pancreata of cats euthanized due to disease, and to evaluate insulin secretion responses to various physiological and pharmacological stimuli. Collagenase digestion of pancreatic tissue from 13 non-diabetic cats and two cats with diabetic ketoacidosis yielded individual islets surrounded by a layer of exocrine tissue that was reduced after two days in culture. Histological examination showed islet amyloid in pancreatic biopsies from most non-diabetic and in one diabetic cat. Islets from non-diabetic cats cultured at 5.5 mM glucose responded with increased insulin secretion to 16.7 mM glucose, 30 mM K⁺ and 20 µM of the sulfonylurea glipizide (2-3 times basal secretion at 3 mM glucose). The glucagon-like peptide-1 receptor agonist exendin-4 (100 nM) had no effect under basal conditions but potentiated glucose-triggered insulin release. Only one of nine islet batches from diabetic cats released detectable amounts of insulin, which was enhanced by exendin-4. Culture of islets from non-diabetic cats at 25 mM glucose impaired secretion both in response to glucose and K⁺ depolarization. In conclusion, we describe a procedure for isolation of islets from cat pancreas biopsies and demonstrate that isolated cat islets secrete insulin in response to glucose and antidiabetic drugs. The study provides a basis for future ex vivo studies of islet function relevant to the understanding of the pathophysiology and treatment of feline diabetes.

Laparoscopic ovum pick-up (LOPU) combined with in vitro embryo production (IVEP) is a technology platform that improves the utilization rate of the elite ewe's ovarian oocytes and increases the number of obtained offspring. This study aimed to evaluate the effects of FSH pre-stimulation, serial oocyte collection, and breed on LOPU-IVEP under field conditions. Donors were randomly assigned to five groups (group A: decreasing doses of pituitary FSH (p-FSH); group B: constant doses of p-FSH; group C: two doses of long-acting recombinant ovine FSH (ro-FSH); group D: single administration of a long-acting ro-FSH in; group E: no FSH stimulation). Oocyte yield following LOPU (average recovered oocytes: 20.9 ± 0.5; average viable oocytes: 17.2 ± 0.4) and oocyte developmental competence (average blastocysts: 7.0 ± 0.2) in group C were significantly better than these of group D and group E, and similar to these of groups A and B. Meanwhile, there were no differences in oocyte yield and developmental capacity using repeated LOPU session at 1-, 2-, and 3-month intervals (p > 0.05). Finally, we compared LOPU-IVEP outcomes among five sheep breeds. The results indicated that East Friesian × Chinese Mongolian crossbred sheep and purebred East Friesian sheep had the more recovered oocytes and viable oocytes compared with the Suffolk, Dorper, and Texel breeds, and average number of blastocysts in East Friesian × Chinese Mongolian sheep group was also highest among the groups (8.1 ±0.3, p < 0.05). In summary, the results of this study indicate long-acting ro-FSH pre-stimulation combined with 12 times LOPU sessions over one year maximizes embryo production of elite donor ewes under field conditions.

This study aims to evaluate the effects of melatonin and its mechanisms of action on preantral follicle activation and survival, stromal cell density and collagen distribution in extracellular matrix (ECM). The involvement of melatonin receptors and mTORC1 pathway in these procedures were also investigated. To this end, ovarian fragments were cultured for six days in α‐MEM⁺ alone or supplemented with 1000 pM melatonin, 1000 pM melatonin with 1000 pM luzindole (inhibitor of melatonin receptors), or 1000 pM melatonin with 0.16 µg/ml rapamycin (mTORC1 inhibitor). At the end of culture period, tissues were processed for classical histology, and the follicles were classified as normal or degenerated, as well as in primordial or growing follicles. The ovarian stromal cell density and ECM collagen distribution were also evaluated. Samples of ovarian tissues were also destined to measure the levels of thiol and mRNA for CAT, SOD, GPX1 and PRDX1, as well as the activity of antioxidant enzymes CAT, SOD, and GPX1. The results demonstrated that ovarian tissues cultured with melatonin, melatonin with luzindole or melatonin with rapamycin had significantly higher percentage of morphologically normal follicles than those cultured in control medium (α‐MEM⁺). However, the presence of either luzindole or rapamycin, did not block the positive effects of melatonin on follicle survival (P > 0.05). Although the presence of melatonin in culture medium reduced the percentage of primordial follicles and increased the percentage of development follicles, these positive effects of melatonin were blocked by either luzindole or rapamycin (P < 0.05). Melatonin, melatonin with luzindole or melatonin with rapamycin did not influence the number of ovarian stromal cells. In contrast, melatonin significantly increased the percentages of collagen in ovarian tissues, but the positive effects of melatonin were blocked by either luzindole or rapamycin. Tissues cultured with melatonin and rapamycin had higher levels of mRNA for CAT and lower GPx activity when compared to those cultured in control medium. In conclusion, melatonin promotes primordial follicle activation, increases collagen fiber in ECM of in vitro cultured bovine ovarian tissue through its membrane-coupled receptors and mTORC1. Oppositely, melatonin increase follicles survival by acting through other pathways, since it can pass through cell membranes and directly regulate oxidative stress.

In this study, changes in salivary and serum proteome of dogs with hypothyroidism were studied using tandem mass tags (TMT) labelling and liquid chromatography-mass spectrometry (LC-MS/MS). Saliva and serum proteome from 10 dogs with hypothyroidism were compared with 10 healthy dogs. In saliva, a total of seven proteins showed significant changes between the two groups, being six downregulated and one upregulated, meanwhile, in serum, a total of six proteins showed significant changes, being five downregulated and one upregulated. The altered proteins reflected metabolic and immunologic changes, as well as, skin and coagulation alterations, and these proteins were not affected by gender. One of the proteins that were downregulated in saliva, lactate dehydrognease (LDH), was measured by a spectrophotometric assay in saliva samples from 42 dogs with hypothyroidism, 42 dogs with non-thyroid diseases and 46 healthy dogs. The activity of LDH was lower in the saliva of hypothyroid dogs when compared to non-thyroid diseased dogs and healthy controls.

This study indicates that canine hypothyroidism can produce changes in the proteome of saliva and serum. These two sample types showed different variations in their proteins reflecting physiopathological changes that occur in this disease, mainly related to the immune system, metabolism, skin and coagulation. In addition, some of the proteins identified in this study, specially LDH in saliva, should be further explored as potential biomarkers of canine hypothyroidism.