Interactions between β-endorphin and kisspeptin neurons of the ewe arcuate nucleus are modulated by photoperiod

International audienceOpioid peptides are well-known modulators of the central control of reproduction. Among them, dynorphin coexpressed in kisspeptin (KP) neurons of the arcuate nucleus (ARC) has been thoroughly studied for its autocrine effect on KP release through κ opioid receptors. Other studies have suggested a role for β-endorphin (BEND), a peptide cleaved from the proopiomelanocortin (POMC) precursor, on food intake and central control of reproduction. Similarly to KP, BEND content in the ARC of sheep is modulated by day length and BEND modulates food intake in a dose-dependent manner. As KP levels in the ARC vary with photoperiodic and metabolic status, a photoperiod-driven influence of BEND neurons on neighboring KP neurons is plausible. The aim of this study was therefore to investigate a possible modulatory action of BEND on KP neurons located in the ovine ARC. Using confocal microscopy, numerous KP appositions on BEND neurons were found but there was no photoperiodic variation in the number of these interactions in ovariectomized, estradiol-replaced ewes. In contrast, BEND terminals on KP neurons were twice as numerous under short days (SD), in ewes having an activated gonadotropic axis, as compared to anestrus ewes under long days (LD). Injection of 5µg BEND into the third ventricle of SD ewes induced a significant and specific increase of activated KP neurons (16% versus 9% in controls) while the percentage of overall activated (c-Fos positive) neurons, was similar between both groups. These data suggest a photoperiod-dependent influence of BEND on KP neurons of the ARC, which may influence GnRH pulsatile secretion and inform KP neurons on the metabolic status

Deoxynivalenol as a new factor in the persistence of intestinal inflammatory diseases: An emerging hypothesis through possible modulation of Th17-mediated response

Background/Aims: Deoxynivalenol (DON) is a mycotoxin produced by Fusarium species which is commonly found in temperate regions worldwide as a natural contaminant of cereals. It is of great concern not only in terms of economic losses but also in terms of animal and public health. The digestive tract is the first and main target of this food contaminant and it represents a major site of immune tolerance. A finely tuned cross-talk between the innate and the adaptive immune systems ensures the homeostatic equilibrium between the mucosal immune system and commensal microorganisms. The aim of this study was to analyze the impact of DON on the intestinal immune response. Methodology: Non-transformed intestinal porcine epithelial cells IPEC-1 and porcine jejunal explants were used to investigate the effect of DON on the intestinal immune response and the modulation of naive T cells differentiation. Transcriptomic proteomic and flow cytometry analysis were performed. Results: DON induced a pro-inflammatory response with a significant increase of expression of mRNA encoding for IL-8, IL-1 alpha and IL-1 beta, TNF-alpha in all used models. Additionally, DON significantly induced the expression of genes involved in the differentiation of Th17 cells (STAT3, IL-17A, IL-6, IL-1 beta) at the expenses of the pathway of regulatory T cells (Treg) (FoxP3, RALDH1). DON also induced genes related to the pathogenic Th17 cells subset such as IL-23A, IL-22 and IL-21 and not genes related to the regulatory Th17 cells (rTh17) such as TGF-beta and IL-10. Conclusion: DON triggered multiple immune modulatory effects which could be associated with an increased susceptibility to intestinal inflammatory diseases

Influence of transvaginal ultrasound-guided follicular punctures on heart rate, respiratory rate, facial expression changes and salivary cortisol in the mare as pain scoring

Transvaginal ultrasound-guided follicular punctures are widely used in the mare for diagnosis, research and commercial applications. The objective of our study was to determine their influence on pain, stress and well-being in the mare, by evaluating heart rate, breath rate, facial expression changes and salivary cortisol before, during and after puncture. For this experiment, 21 pony mares were used. Transvaginal ultrasound-guided aspirations were performed on 11 mares. After injections for sedation, analgesia and antispasmodia, the follicles from both ovaries were aspirated with a needle introduced through the vagina wall into the ovary. In the control group, 10 mares underwent similar treatments and injections, but no follicular aspiration. Along the session, heart rate and breath rate were evaluated by a trained veterinarian, ears position, eyelid closure and contraction of facial muscles were evaluated and salivary samples were taken for evaluation of cortisol concentration. A significant relaxation was observed after sedative injection in the punctured and control mares, according to ear position, eyelid closure and contraction of facial muscles, but no difference between punctured and control animals was recorded. No significant modification of salivary cortisol concentration during puncture and no difference between punctured and control mares at any time were observed. No significant modification of the breath rate was observed along the procedure for the punctured and the control mares. Heart rate increased significantly but transiently when the needle was introduced in the ovary and was significantly higher at that time for the punctured mares compared to control mares. None of the other investigated parameters were affected at that time, suggesting discomfort is minimal and transient. Improving analgesia, for example through a multimodal approach, during that possibly more sensitive step could be recommended. The evaluation of facial expression changes and heart rate are easy-to-use and accurate tools to evaluate pain and well-being of the mare

Resistin in dairy cows: plasma concentrations during early lactation, expression and potential role in adipose tissue.

Resistin is an adipokine that has been implicated in energy metabolism regulation in rodents but has been little studied in dairy cows. We determined plasma resistin concentrations in early lactation in dairy cows and investigated the levels of resistin mRNA and protein in adipose tissue and the phosphorylation of several components of insulin signaling pathways one week post partum (1 WPP) and at five months of gestation (5 MG). We detected resistin in mature bovine adipocytes and investigated the effect of recombinant bovine resistin on lipolysis in bovine adipose tissue explants. ELISA showed that plasma resistin concentration was low before calving, subsequently increasing and reaching a peak at 1 WPP, decreasing steadily thereafter to reach pre-calving levels at 6 WPP. Plasma resistin concentration was significantly positively correlated with plasma non esterified fatty acid (NEFA) levels and negatively with milk yield, dry matter intake and energy balance between WPP1 to WPP22. We showed, by quantitative RT-PCR and western blotting, that resistin mRNA and protein levels in adipose tissue were higher at WPP1 than at 5 MG. The level of phosphorylation of several early and downstream insulin signaling components (IRβ, IRS-1, IRS-2, Akt, MAPK ERK1/2, P70S6K and S6) in adipose tissue was also lower at 1 WPP than at 5 MG. Finally, we showed that recombinant bovine resistin increased the release of glycerol and mRNA levels for ATGL (adipose triglyceride lipase) and HSL (hormone-sensitive lipase) in adipose tissue explants. Overall, resistin levels were high in the plasma and adipose tissue and were positively correlated with NEFA levels after calving. Resistin is expressed in bovine mature adipocytes and promotes lipid mobilization in adipose explants in vitro

Partie 4. Travailler avec les oiseaux

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Pineal-dependent increase of hypothalamic neurogenesis contributes to the timing of seasonal reproduction in sheep

Abstract To survive in temperate latitudes, species rely on the photoperiod to synchronize their physiological functions, including reproduction, with the predictable changes in the environment. In sheep, exposure to decreasing day length reactivates the hypothalamo-pituitary-gonadal axis, while during increasing day length, animals enter a period of sexual rest. Neural stem cells have been detected in the sheep hypothalamus and hypothalamic neurogenesis was found to respond to the photoperiod. However, the physiological relevance of this seasonal adult neurogenesis is still unexplored. This longitudinal study, therefore aimed to thoroughly characterize photoperiod-stimulated neurogenesis and to investigate whether the hypothalamic adult born-cells were involved in the seasonal timing of reproduction. Results showed that time course of cell proliferation reached a peak in the middle of the period of sexual activity, corresponding to decreasing day length period. This enhancement was suppressed when animals were deprived of seasonal time cues by pinealectomy, suggesting a role of melatonin in the seasonal regulation of cell proliferation. Furthermore, when the mitotic blocker cytosine-b-D-arabinofuranoside was administered centrally, the timing of seasonal reproduction was affected. Overall, our findings link the cyclic increase in hypothalamic neurogenesis to seasonal reproduction and suggest that photoperiod-regulated hypothalamic neurogenesis plays a substantial role in seasonal reproductive physiology

Expression of adipokine and lipid metabolism genes in adipose tissue of dairy cows differing in a female fertility quantitative trait locus

L'article est publié par l'American Dairy Science AssociationWe have previously characterized 2 haplotypes (Fertil+ and Fertil-) of Holstein dairy cows differing in 1 female fertility quantitative trait locus (QTL) located on chromosome 3 (QTL-Fert-F-BTA3) between positions 9.8 and 13.5 cM. This QTL is composed of 124 genes, some of them being involved in metabolism or reproduction. Primiparous Fertil+ and Fertil- cows exhibited 69 and 39% pregnancy rate at first service, respectively. A difference in plasma nonesterified fatty acid concentrations observed between both haplotypes might indicate a difference in adipose tissue mobilization. We compared adipose tissue gene expression in Fertil+ and Fertil- cows during their second lactation, at 2 physiological stages, implying either intense lipid mobilization (1 wk postpartum) or fat storage (5 mo of gestation). We investigated by reverse-transcription quantitative PCR the mRNA gene expression of 5 positional candidate genes located in the QTL-Fert-F-BTA3, as well as 18 other functional candidate genes encoding proteins involved in lipid metabolism and several adipokines. Among them, genes involved in either lipolysis or lipogenesis were chosen as controls because they were previously described in dairy cow adipose tissue. A hierarchical clustering was performed to group genes according to their expression pattern, allowing 2 clusters to be determined. Cluster 1 was composed of genes that were overexpressed during mobilization (ADIPOQ, ADIPOR2, LIPE, FABP4, PLIN1, RARRES, LEPR, and CPT1A) and cluster 2 of genes overexpressed during reconstitution of body reserves (ACACA, FASN, and SCD). Genes belonging to cluster 1 (LIPE, FABP4, PLIN1, and CPT1A) are known to be involved in lipolysis and fatty acid oxidation, and genes belonging to cluster 2 (ACACA, FASN, and SCD) are known to be involved in fatty acid synthesis. The expression of 5 genes from cluster 1 was correlated to plasma nonesterified fatty acid levels and thus to mobilization of body reserves in dairy cows (ADIPOQ, ADIPOR2, LIPE, PLIN1, and FABP4). During the mobilization stage, none of the positional candidate genes belonging to QTL-Fert-F-BTA3 (ADAR, MTX1, SHC1, SPTA1, and PAQR6) showed a difference in expression between the 2 haplotypes. Interestingly, ADIPOQ and ADIPOR2 were the only genes showing a significant mRNA overexpression in Fertil- cows at the mobilization stage. Further studies focusing on plasma adiponectin level and adipokine actions on the ovary are needed to investigate its potential role in dairy cow fertility

Plasma resistin, NEFA, glucose and insulin levels at 1 week post partum (WPP 1) and 5 months of gestation (5 MG) during the second lactation.

<p>Plasma resistin, NEFA, glucose and insulin concentrations measured on the day of adipose tissue biopsy (1 WPP and 5 MG) in Holstein dairy cows. Animals (<i>n</i> = 8 in each group) were fasted for 12 hours before surgery Results are presented as means ± SEM. Results are considered significantly different if <i>p</i><0.05. * and *** indicate significant differences at <i>p</i><0.05 and <i>p</i><0.0001, respectively.</p

Levels of tyrosine phosphorylation for IR, IGF-1R, IRS-1 and IRS-2 in bovine adipose tissue at one week post partum (1 WPP) and 5 months of gestation (5 MG).

<p>Western blots showing the tyrosine phosphorylation levels of IRβ (A), IGF-1Rβ (B), IRS-1 (C) and IRS-2 (D) in adipose tissue lysates from dairy cows at one week post partum (1 WPP, <i>n</i> = 8 animals) and 5 of months gestation (5 MG, <i>n</i> = 8 animals). Immunoprecipitation (IP) was performed before gel electrophoresis. The antibody used is indicated as follows: IP: molecule X; the immune sera used to determine protein phosphorylation levels are indicated to the left of the gels (e.g., PY20 is directed against anti-phosphotyrosine residues). The levels of phosphorylation of IR, IGF-1R, IRS1 and IRS-2 were normalized with respect to the corresponding total protein, with specific antibodies, as indicated to the left of the gels. The gels show protein bands, which are underlined for each group, with four dairy cows per group. From left to the right, the groups are 1 WPP and 5 MG. Below each gel, the histograms show the mean ± SEM for a total of <i>n</i> = 8/group. *indicates a significant difference (<i>p</i><0.05).</p

Early Castration in Horses Does Not Impact Osteoarticular Metabolism

The castration of stallions is traditionally performed after puberty, at around the age of 2 years old. No studies have focused on the effects of early castration on osteoarticular metabolism. Thus, we aimed to compare early castration (3 days after birth) with traditional castration (18 months of age) in horses. Testosterone and estradiol levels were monitored from birth to 33 months in both groups. We quantified the levels of biomarkers of cartilage and bone anabolism (CPII and N-MID) and catabolism (CTX-I and CTX-II), as well as of osteoarthritis (HA and COMP) and inflammation (IL-6 and PGE2). We observed a lack of parallelism between testosterone and estradiol synthesis after birth and during puberty in both groups. The extra-gonadal synthesis of steroids was observed around the 28-month mark, regardless of the castration age. We found the expression of estrogen receptor (ESR1) in cartilage and bone, whereas androgen receptor (AR) expression appeared to be restricted to bone. Nevertheless, with respect to osteoarticular metabolism, steroid hormone deprivation resulting from early castration had no discernable impact on the levels of biomarkers related to bone and cartilage metabolism, nor on those associated with OA and inflammation. Consequently, our research demonstrated that early castration does not disrupt bone and cartilage homeostasis