Chemerin Impairs In Vitro Testosterone Production, Sperm Motility, and Fertility in Chicken: Possible Involvement of Its Receptor CMKLR1

Chronic dietary exposure to a glyphosate-based herbicide alters ovarian functions in young female broilers

Glyphosate (GLY)-based herbicide (GBH) formulations are widely used pesticides in agriculture. The European Union recently decided to extend the use of GLY in Europe until 2034. Previously, we showed that chronic dietary GBH exposure in adult hens resulted in a reversible increase in early mortality in chicken embryos. In this present study, we investigated the GBH effects on metabolism and ovarian functions by using a transcriptomic approach in vivo in young female broilers and in vitro in ovarian explant cultures. We exposed 11-day-old female broilers to 13 mg GLY equivalent/kg body weight/d (GBH13, n = 20), 34 mg GLY equivalent/kg body weight/d (GBH34, n = 20), or a standard diet (control [CT], n = 20) for 25 d. These 2 GBH concentrations correspond to approximatively one-eighth and one-third of the no observed adverse effect level (NOAEL) as defined by European Food Safety Authority in birds. During this period, we evaluated body weight, fattening, food intake, and the weight of organs (including the ovaries). Chronic dietary GBH exposure dose dependently reduced food intake, body weight, and fattening, but increased oxidative stress and relative ovary weight. We analyzed the ovarian gene expression profile in CT, GBH13, and GBH34 broilers with RNA sequencing and showed that differentially expressed genes are mainly enriched in pathways related to cholesterol metabolism, steroidogenesis, and RNA processing. With quantitative polymerase chain reaction and western blotting, we confirmed that GBH decreased ovarian STAR and CYP19A1 messenger RNA and protein expression, respectively. Furthermore, we confirmed that GBH altered steroid production in ovarian explants. We have identified potential regulatory networks associated with GBH. These data provide valuable support for understanding the ovarian transcriptional regulatory mechanism of GBH in growing broilers.

Comparative expression and localization of visfatin, chemerin, and chemerin receptor proteins in a heat-stressed mouse testis

The adipokines, visfatin, chemerin, and its receptor are expressed in the testis. It has also been shown that heat-stress alters the secretion and expression of other adipokines. Testicular heat-stress is now well known to cause the impairment in the testis. It has also been documented that heat-stress changes the expression of genes and proteins in the testis. To the best of our knowledge, the expression and localization of visfatin chemerin and its receptor have not been investigated in the heat-stressed testis. Therefore, the present study has investigated the expression and localization of these proteins in the heat-stressed testis. The expression of visfatin and chemerin and receptor exhibits a differential repossess against the heat stress. Visfatin expression was up-regulated while chemerin and chemerin receptor was down-regulated in the heat-stressed testis as shown by western blot analysis. The immunolocalization of visfatin and chemerin showed increased abundance in the seminiferous tubules of heat-stressed mice testis. Furthermore, abundance of visfatin, chemerin, and its receptor showed a decrease in abundance in the Leydig cells of heat-stressed testis. The decreased abundance of these proteins in the Leydig cells coincides with decreased 3β-HSD immunostaining along with decreased testosterone levels. These results suggest that heat-stress might decrease testosterone secretion by modulating visfatin and chemerin in the Leydig cells. The increased abundance of visfatin and chemerin in the primary spermatocytes, round spermatid, and multinucleated germ cells also coincides with increased immunostaining of active caspase-3. Moreover, expression of Bcl-2 was down-regulated, and expression of active caspase-3 and HSP70 were up-regulated along with increased oxidative stress in the heat-stressed testis, suggesting stimulated apoptosis. In conclusion, our results showed that visfatin, chemerin, and its receptor are differentially expressed in the testis under heat-stress and within the testis also it might differentially regulate testosterone biosynthesis in the Leydig cells and apoptosis in the seminiferous tubules.

Chemerin affects blood lipid profile of high-fat diet male mice in sedentary and exercise states via glucose and lipid metabolism enzymes

Adipokine chemerin plays important roles in disorders of glucose and lipid metabolism of obesity and obesity-related diseases, and exercise-induced improvement of glucose and lipid metabolism is closely related to the decrease of chemerin, but the mechanisms by which chemerin regulates glucose and lipid metabolism remain unclarified. Hypotestosterone induces male obesity and disorders of glucose and lipid metabolism through androgen receptor (AR) and its target genes: glucose and lipid metabolism-related molecules (including FOXO1, PEPCK, PGC-1α, and SCD1). Recently, the link between them has been reported that chemerin modulated the secretion of androgen. In this study, global chemerin knockout (chemerin (-/-)) mice were established to demonstrate the roles of chemerin in regulating blood glucose and blood lipid of mice under diet (high-fat (HFD) and normal diet) and exercise interventions and then to explore its mechanisms (AR - glucose and lipid metabolism enzymes). We found that the blood lipid and adipocyte size were low accompanied by the improvements in the levels of serum testosterone, gastrocnemius AR, and gastrocnemius FOXO1, SCD1, and PGC-1α in HFD chemerin (-/-) mice, but exercise-induced improvements of these indicators in HFD WT mice were attenuated or abolished in HFD chemerin (-/-) mice. In conclusion, the decrease of chemerin improved the blood lipid profile of HFD male mice at sedentary and exercise states, mediated partly by the increases of testosterone and AR to regulate glucose and lipid metabolism enzymes. To our knowledge, it is the first report that chemerin's regulation of glucose and lipid metabolism might be mediated by testosterone and AR in vivo.

Anabolic steroids induced changes at the level of protein expression: Effects of prolonged administration of testosterone and nandrolone to pigs

Synthetic derivatives of steroid hormones, specifically anabolic-androgenic steroids (AAS), have gained prominence due to their observed benefits in enhancing meat quality. The study replicated the administration of banned AAS and investigated their impacts on pigs to contribute to the understanding of animal biochemistry and to explore the feasibility of detecting AAS administration by employing a non-targeted analysis. The effects were corroborated by evaluating changes in the expression of selected proteins, as well as examining haematological and biochemical profiles and histological alterations. Exposure to AAS influenced the expression of proteins related to drug-metabolizing enzymes, muscle and lipid metabolism, kidney function, reproductive processes, immune system functions, and carcinogenic changes. The effects of AAS appear intricate and contingent on factors such as the specific drug used, dosage, and duration of administration. The results underscore that protein expression analysis holds promise as a valuable tool for detecting illicit AAS use in the fattening process.

Expression of chemerin and its receptors in extra-embryonic annexes and role of chemerin and its GPR1 receptor in embryo development in layer and broiler hens

Intensive genetic selection of broiler breeders and layer hens resulted in differences in the mechanisms of growth and also in cell metabolism during embryogenesis. Previous research has shown that an adipokine named chemerin and one of these receptors, CMKLR1 were potentially involved in broiler embryo development. Here, our objectives were 1) to compare the expression of chemerin and its receptors CMKLR1, GPR1, and CCRL2 and chemerin concentration in extra-embryonic annexes (allantoic and amniotic membranes and fluids and plasma) in broiler and layer fertile eggs during the development (embryonic day (ED) 7, 14, and 18) by RT-qPCR and specific chicken ELISA and 2) to investigate the role of chemerin and one of its receptors GPR1 in embryo development after in ovo injections of neutralizing antibodies against chicken chemerin and GPR1. We found that chemerin expression in amniotic membranes was higher in layer than broiler eggs at ED7 and ED14 whereas the expression of the 3 receptors was higher in layer than broiler in the allantoic membranes at ED14 and ED18. Chemerin concentration was more important in layer than broiler at ED14 and ED18 in amniotic liquid and at all the studied stages in blood plasma. We also showed positive correlation between amniotic chemerin concentration and chemerin amniotic membrane expression, chemerin plasma concentration and embryo body weight in both breeds. Finally, in ovo injection of chicken chemerin and GPR1 neutralizing antibodies increased embryo mortality in both layer and broiler eggs. Taken together, even if chemerin concentration and chemerin system expression in embryonic membranes are mainly higher expressed in layer than in broiler, chemerin potentially through GPR1 could promote embryo development in both breeds.

Adropin may promote insulin stimulated steroidogenesis and spermatogenesis in adult mice testes

Adropin is a versatile peptide which was discovered as a novel metabolic hormone that is involved in the regulation of lipid and glucose homeostasis. However, its possible role in the testicular function is not yet understood. The aim of our study was to explore the distribution pattern of adropin and GPR19 in various cell types and its possible role in testicular functions of adult mice. Immunohistochemical study revealed the intense immunoreactivity of adropin in the Leydig cells, while GPR19 showed intense immunoreactivity in the pachytene spermatocytes and mild immunoreactivity in Leydig cells and primary as well as secondary spermatocytes in mouse testis. Enho mRNA was also found to be expressed in the mouse testis. These findings suggested that adropin-GPR19 signaling may act in autocrine/paracrine manner to modulate testicular functions. Furthermore, to find out the direct role of adropin in the testicular function, in vitro study was performed in which testicular slices were cultured with adropin alone (10 and 100 ng/mL) and in combination with insulin (5 μg/mL). Adropin alone inhibited testicular testosterone synthesis by inhibiting the expression of P450-SCC, 3β-HSD, and 17β-HSD while along with insulin stimulated the testicular testosterone synthesis by increasing the expression of GPR19, IR, StAR, P450-SCC, 3β-HSD, and 17β-HSD. Adropin alone or in combination with insulin promoted germ cell survival and proliferation by upregulating the expression of PCNA, Bcl2, and pERK1/2. Thus, it can be concluded that adropin-GPR19 signaling promotes insulin stimulated steroidogenesis and germ cell survival as well as proliferation in the mice testes in an autocrine/paracrine manner.

In vitro exposure to triazoles used as fungicides impairs human granulosa cells steroidogenesis

Triazoles are the main components of fungicides used in conventional agriculture. Some data suggests that they may be endocrine disruptors. Here, we found five triazoles, prothioconazole, metconazole, difenoconazole, tetraconazole, and cyproconazole, in soil or water from the Centre-Val de Loire region of France. We then studied their effects from 0.001 µM to 1000 µM for 48 h on the steroidogenesis and cytotoxicity of ovarian cells from patients in this region and the human granulosa line KGN. In addition, the expression of the aryl hydrocarbon receptor (AHR) nuclear receptor in KGN cells was studied. Overall, all triazoles reduced the secretion of progesterone, estradiol, or both at doses that were non-cytotoxic but higher than those found in the environment. This was mainly associated, depending on the triazole, with a decrease in the expression of CYP51, STAR, CYP11A1, CYP19A1, or HSD3B proteins, or a combination thereof, in hGCs and KGN cells and an increase in AHR in KGN cells.

Adipokines expression in reproductive tract, egg white and embryonic annexes in hen

In mammals, molecules mainly secreted by white adipose tissue named adipokines are also synthetized locally in the reproductive tract and are able to influence reproductive functions. In avian species, previous studies indicated that the adipokine chemerin is highly abundant in the albumen, compared to the yolk and this was associated to high chemerin expression in the magnum. In addition, the authors observed that chemerin and its receptors are expressed by allantoic and amniotic membranes and chemerin is present in fluids during the embryo development. Here, we studied other adipokines, including adiponectin, visfatin, apelin, and adipolin in egg white and their known receptors in the active (egg-laying hen) and regressed (hen not laying) oviduct and embryonic annexes during embryo development. By using Western blot, RT-qPCR analysis and immunohistochemistry, we demonstrated the expression of different adipokines in the egg albumen (visfatin) and the reproductive tract (adiponectin, visfatin, apelin, adipolin, and their cognate receptors) according the position of egg in the oviduct. We showed that the expression of adipokines and adipokines receptors was strongly reduced in the regressed oviducts (arrested laying hen). Results indicated that visfatin and adiponectin appeared at ED11 to 14 and increased until ED18 in amniotic fluid whereas it was found from ED7 and was unchanged during embryo development in allantoic fluid. Taken together, adipokines and their receptors are expressed in the egg white, the reproductive tract and the embryonic annexes. Data obtained suggest important functions of theses metabolic hormones during the chicken embryo development. Thus, adipokines could be potential biomarkers to improve the embryo development.

Chronic dietary exposure to a glyphosate-based herbicide in broiler hens has long-term impacts on the progeny metabolism

Glyphosate-based herbicides (GBH) are the most commonly used herbicides in agriculture. Several studies reported possible adverse effects on human and animal models after a GBH exposure. However, the effects of a temporary maternal exposure on the progeny have been poorly documented, especially in avian models. We investigated the effects of a hen chronic dietary exposure to a GBH on the progeny, obtained during the period following the withdrawal of GBH from the diet. Hens were exposed to a GBH via their food for 6 wk, after which the GBH was removed from their food. Eggs from these hens were collected 3 wk after the GBH was withdrawn for 1 wk. We monitored the growth performances, metabolic parameters, and behavior from the progeny of the hens (Ex-GBH chicks, n = 186) and compared them with those of unexposed control-hen progeny (CT chicks, n = 213). Ex-GBH chicks were more likely to explore their new environment than CT chicks during the open-field test. In addition, they had an increased fattening and blood triglycerides level, whereas their food consumption was similar to CT chicks. Quantitative PCR on the chemerin system and FASN in chicks livers indicate a transcriptional activity in favor of fatty acid synthesis, and lipidomic analysis on chicks abdominal adipose tissue reveal a global increase in monounsaturated fatty acid and a global decrease in polyunsaturated fatty acids. Seven genes involved in the synthesis of fatty acids were identified with the open access LIPIDMAP software, and their disturbance in Ex-GBH chicks was confirmed via qPCR. Taken together, these results suggest that the progeny of hens temporarily exposed to a GBH are more likely to fatten, even with a balanced diet. The removal of GBH from their contaminated environment would therefore not be sufficient to completely restore their health, has it could induce transgenerational effects.

Triazole pesticides exposure impaired steroidogenesis associated to an increase in AHR and CAR expression in testis and altered sperm parameters in chicken

Since several decades, we observe the decline of various bird populations that could be partly linked to the agricultural intensification and the use of large amount of pesticides. Even if triazoles compounds are the most widely used fungicides, their effects on the reproductive parameters in birds are not clearly known. In the present study, we investigated the in vitro effects of 8 triazoles compounds alone (propiconazole (PP, from 0 to 10 µM), prothioconazole (PT), epoxiconazole (Epox), tetraconazole (TT), tebuconazole (TB), difenoconazole (Dif), cyproconazole (Cypro), metconazole (MC) (from 0 to 1 mM)) on the male chicken reproductive functions by using testis explants, primary Sertoli cells and sperm samples. In testis, all triazoles at the higher concentrations for 48 h inhibited lactate and testosterone secretion mostly in association with reduced expression of HSD3B and/or STAR mRNA levels. These data were also associated with increased expression of the nuclear receptors Aryl Hydrocarbon Receptor (AHR) and Constitutive Androstane Receptor (CAR) mRNA levels in testis and for all triazoles except for PP a reduction in Sertoli cell viability. When focusing on the sperm parameters, we demonstrated that most of the triazoles (MC, Epox, Dif, TB, TT and Cypro) at 0.1 or 1 mM for either 2, 12 or 24 min of exposure decreased sperm motility and velocity and increased the percentage of spermatozoa abnormal morphology. At the opposite, PP increased sperm motility in a dose dependent manner after 2 min of exposure whereas no significant effect was observed in response to PT whatever the dose and the time of exposure. Moreover, these effects were associated with an increase in the production of reactive oxygen species in spermatozoa. Taken together, most of the triazoles compounds impair testis steroidogenesis and semen parameters potentially through an increase in AHR and CAR expression and in oxidative stress, respectively.

Data Availability Statement

All the data will be available.

Identification of hub genes and biological mechanisms underlying the pathogenesis of asthenozoospermia and chronic epididymitis

Objective: Asthenozoospermia (AZS) is one of the most common causes of male fertility, affecting family wellbeing and population growth. Chronic epididymitis (CE) is a common and lingering inflammatory disease in the scrotum. Inflammation in the epididymis has a severe impact on sperm motility. This study aimed to explore the genetic profile and critical pathways involved in the pathological mechanisms of AZS and CE, and discover potential biomarkers. Methods: Genomic datasets of AZS and CE were obtained from the Gene Expression Omnibus (GEO) database, and relevant differentially expressed genes (DEGs) were identified. GO and pathway enrichment analyses, construction of a protein-protein interaction network, and receiver operator characteristic curve analysis were conducted. The expression profile of hub genes was validated in immunohistochemical data and testicular cell data. Immune infiltration, miRNA-hub gene interactions, and gene-disease interactions were explored. The mRNA levels of hub genes were further measured by qRT-PCR. Results: A total of 109 DEGs were identified between the AZS/CE and healthy control groups. Pathways of the immune system, neutrophil degranulation, and interleukin-4 and interleukin-13 signaling were enriched in AZS and CE. Five hub genes (CD300LB, CMKLR1, CCR4, B3GALT5, and CTSK) were selected, and their diagnostic values were validated in AZS, CE, and independent validation sets (area under the curve >0.7). Furthermore, the five-hub gene signature was well characterized in testicular immunohistochemical staining and testicular cells from healthy controls. Immune infiltration analysis showed that infiltration of CD8⁺ cells and T helper cells was significantly related to the expression level of five hub genes. In addition, a miRNA-hub gene network and interaction of other diseases were displayed. The mRNA levels of hub genes (CD300LB, CMKLR1, CCR4, and B3GALT5) were significantly elevated in the patient group. The mRNA level of CTSK also showed a similar trend. Conclusion: Our study uncovered the genetic profile involved in AZS and CE, and elucidated enriched pathways and molecular associations between hub genes and immune infiltration. This finding provides novel insight into the common pathogenesis of both diseases as well as the potential biomarkers for CE-associated AZS.

Comparative Transcriptome Analysis Provided a New Insight into the Molecular Mechanisms of Epididymis Regulating Semen Volume in Drakes

Semen volume is an important factor in artificial insemination (AI) of ducks. In drakes, seminal plasma that is produced by the epididymis determines the semen volume. However, the mechanism of epididymis regulating semen volume of drakes remains unclear. Therefore, the aim of the present study was to preliminarily reveal the mechanism regulating the semen volume through comparing the epididymal histomorphology and mRNA expression profiles between drakes with high-volume semen (HVS) and low-volume semen (LVS). Phenotypically, drakes in the HVS group produced more sperm than drakes in the LVS group. In addition, compared with the HVS group, the ductal square of ductuli conjugentes (DC) and dutus epididymidis (DE) in epididymis was significantly smaller in the LVS group, and the lumenal diameter and epithelial thickness of DC/DE were significantly shorter in the LVS group. In transcriptional regulation, 72 different expression genes (DEGs) were identified from the epididymis between HVS and LVS groups. Gene Ontology (GO) analysis indicated that the DEGs were mainly related to hormone secretion, neurotransmitter synthesis/transport, transmembrane signal transduction, transmembrane transporter activity, and nervous system development (p < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis showed that the DEGs were significantly enriched in pathways associated with hormone and neurotransmitter transmission (p < 0.05). In addition, further analysis of the top five pathways enriched by KEGG, nine key candidate genes (including SLC18A2, SNAP25, CACNA1B, GABRG2, DRD3, CAMK2A, NR5A1, and STAR) were identified, which could play a crucial role in the formation of semen. These data provide new insights into the molecular mechanism regulating semen volume of drakes and make feasible the breeding of drakes by semen volume.

Chicken white egg chemerin as a tool for genetic selection for egg weight and hen fertility

Embryo mortality rate, which can reach up to 40% in avian species, is a major issue for breeding. It is therefore important to identify new embryo development biomarkers for genetic selection to improve reproductive performances. We have recently shown that chemerin is expressed in the oviductal hen magnum, accumulates in egg white, is correlated with embryo survival and could thus be used as a molecular marker of embryo development. Eggs from seven hen breeds (n = 70) were collected during five successive days at the end of the laying period. After weighing eggs, yolk and albumen, an egg white sample from each egg was collected and a blood sample was taken from each hen. Chemerin concentrations in albumen and blood samples were measured by a specific home made ELISA assay. Hen's plasma and egg's albumen chemerin levels were found to be correlated with reproductive parameters such as fecundity, fertility, embryo mortality, hatchability and laying rates. The inter-hen chemerin level variability in albumen was higher than intra-hen except for one breed (R+). We observed significantly different levels of chemerin in egg white between breeds. However, chemerin concentrations in egg white were not significantly associated to variations of hen plasma chemerin levels. Interestingly, we observed negative correlations between albumen chemerin concentrations and egg weight (r = -0.43, p = 0.001), between albumen weight (r = -0.40, p = 0.002), and between yolk weight (r = -0.28, p = 0.03). We also showed negative correlations between egg white chemerin concentrations and fecundity (r = -0.32, p = 0.011) and fertility (r = -0.27, p = 0.04) whereas no significant correlation was observed with the laying rate. Taken together, these results suggest that egg white chemerin concentration might be a good biomarker for genetic selection for egg weight and fertility in hens, provided these data are confirmed on a larger scale.

Chronic dietary exposure to a glyphosate-based herbicide results in total or partial reversibility of plasma oxidative stress, cecal microbiota abundance and short-chain fatty acid composition in broiler hens

Glyphosate-based herbicides (GBHs) are massively used in agriculture. However, few studies have investigated the effects of glyphosate-based herbicides on avian species although they are largely exposed via their food. Here, we investigated the potential reversibility of the effects of chronic dietary exposure to glyphosate-based herbicides in broiler hens. For 42 days, we exposed 32-week-old hens to glyphosate-based herbicides via their food (47 mg/kg/day glyphosate equivalent, glyphosate-based herbicides, n = 75) corresponding to half glyphosate’s no-observed-adverse-effect-level in birds. We compared their performance to that of 75 control animals (CT). Both groups (glyphosate-based herbicides and control animals) were then fed for 28 additional days without glyphosate-based herbicides exposure (Ex-glyphosate-based herbicides and Ex-control animals). Glyphosate-based herbicides temporarily increased the plasma glyphosate and AMPA (aminomethylphosphonic acid) concentrations. Glyphosate and aminomethylphosphonic acid mostly accumulated in the liver and to a lesser extent in the leg muscle and abdominal adipose tissue. Glyphosate-based herbicides also temporarily increased the gizzard weight and plasma oxidative stress monitored by TBARS (thiobarbituric acid reactive substances). Glyphosate-based herbicides temporarily decreased the cecal concentrations of propionate, isobutyrate and propionate but acetate and valerate were durably reduced. The cecal microbiome was also durably affected since glyphosate-based herbicides inhibited Barnesiella and favored Alloprevotella. Body weight, fattening, food intake and feeding behavior as well as plasma lipid and uric acid were unaffected by glyphosate-based herbicides. Taken together, our results show possible disturbances of the cecal microbiota associated with plasma oxidative stress and accumulation of glyphosate in metabolic tissues in response to dietary glyphosate-based herbicides exposure in broiler hens. Luckily, glyphosate-based herbicides at this concentration does not hamper growth and most of the effects on the phenotypes are reversible.

Chemerin: A Functional Adipokine in Reproductive Health and Diseases

As a multifaceted adipokine, chemerin has been found to perform functions vital for immunity, adiposity, and metabolism through its three known receptors (chemokine-like receptor 1, CMKLR1; G-protein-coupled receptor 1, GPR1; C-C motif chemokine receptor-like 2, CCRL2). Chemerin and the cognate receptors are also expressed in the hypothalamus, pituitary gland, testis, ovary, and placenta. Accumulating studies suggest that chemerin participates in normal reproduction and underlies the pathological mechanisms of certain reproductive system diseases, including polycystic ovary syndrome (PCOS), preeclampsia, and breast cancer. Herein, we present a comprehensive review of the roles of the chemerin system in multiple reproductive processes and human reproductive diseases, with a brief discussion and perspectives on future clinical applications.

Chemerin is secreted by the chicken oviduct, accumulates in egg albumen and could promote embryo development

Understanding of the distribution of chemerin and its receptors, Chemokine-like Receptor 1 (CMKLR1), G Protein-coupled Receptor 1 (GPR1) and Chemokine (C–C motif) receptor-like 2 (CCRL2), in the egg and the embryonic annexes is currently lacking, and their role during embryogenesis remains unknown. By immunoblot using monoclonal anti-chicken antibodies and Enzyme Linked Immunosorbent Assays (ELISA), we found that chemerin is expressed 10 times higher in albumen eggs than in blood plasma, and it is also abundant in the perivitelline membrane but undetectable in yolk. Chicken chemerin can inhibit bacterial growth. By Reverse Transcription—quantitative Polymerisation Chain Reaction (RT-qPCR), western-blot, and immunofluorescence, we show that chemerin is locally produced by the oviduct magnum that participates in albumen formation. Using cultures of magnum explants, we demonstrate that progesterone (P4) and oestradiol (E2) treatment increases chemerin secretion into cultured media and expression in magnum. Chemerin and its three receptors are present in amniotic and Chorio Allantoic Membranes (CAM). Only CMKLR1 expression decreased from embryonic day (ED) 7 to ED11 and remained low until ED18. Chemerin concentrations strongly increased in amniotic fluid at D14 when egg albumen crossed the amniotic membrane. In ovo injections of neutralising chemerin and CMKLR1 antibodies (0.01, 0.1 and 1 µg) increased embryo mortality, which occurred mainly at ED12-13, in a dose-dependent manner. Chemerin treatment increased primary CAM viability. Finally, chemerin and CMKLR1 inhibition within the CAM led to a decrease in blood vessel development and associated angiogenic gene expression. Our results show an important function of the chemerin system during embryo development in chickens, suggesting the potential use of this adipokine as a predictive marker for egg fertility or hatchability.

Chronic Dietary Exposure of Roosters to a Glyphosate-Based Herbicide Increases Seminal Plasma Glyphosate and AMPA Concentrations, Alters Sperm Parameters, and Induces Metabolic Disorders in the Progeny

The effects of chronic dietary Roundup (RU) exposure on rooster sperm parameters, fertility, and offspring are unknown. We investigated the effects of chronic RU dietary exposure (46.8 mg kg⁻¹ day⁻¹ glyphosate) for 5 weeks in 32-week-old roosters (n = 5 RU-exposed and n = 5 control (CT)). Although the concentrations of glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) increased in blood plasma and seminal fluid during exposure, no significant differences in testis weight and sperm concentrations were observed between RU and CT roosters. However, sperm motility was significantly reduced, associated with decreased calcium and ATP concentrations in RU spermatozoa. Plasma testosterone and oestradiol concentrations increased in RU roosters. These negative effects ceased 14 days after RU removal from the diet. Epigenetic analysis showed a global DNA hypomethylation in RU roosters. After artificial insemination of hens (n = 40) with sperm from CT or RU roosters, eggs were collected and artificially incubated. Embryo viability did not differ, but chicks from RU roosters (n = 118) had a higher food consumption, body weight and subcutaneous adipose tissue content. Chronic dietary RU exposure in roosters reduces sperm motility and increases plasma testosterone levels, growth performance, and fattening in offspring.

Adipokines in metabolic and reproductive functions in birds: An overview of current knowns and unknowns

Adipose tissue is now recognized as an active endocrine organ, which synthesizes and secretes numerous peptides factors called adipokines. In mammals, they exert pleiotropic effects affecting energy metabolism but also fertility. In mammals, secretion of adipokines is altered in adipose tissue dysfunctions and may participate to obesity-associated disorders. Thus, adipokines are promising candidates both for novel pharmacological treatment strategies and as diagnostic tools. As compared to mammals, birds exhibit several unique physiological features, which make them an interesting model for comparative studies on endocrine control of metabolism and adiposity and reproductive functions. Some adipokines such as leptin and visfatin may have different roles in avian species as compared to mammals. In addition, some of them found in mammals such as CCL2 (chemokine ligand 2), resistin, omentin and FGF21 (Fibroblast Growth factor 21) have not yet been mapped to the chicken genome model and among its annotated gene models. This brief review aims to summarize data (structure, metabolic and reproductive roles and molecular mechanisms involved) related to main avian adipokines (leptin, adiponectin, visfatin, and chemerin) and we will briefly discuss the adipokines that are still lacking in avian species.

Chemerin impairs food intake and body weight in chicken: Focus on hypothalamic neuropeptides gene expression and AMPK signaling pathway

Unlike mammals, the role of adipokines and more particularly of chemerin in the regulation of food intake is totally unknown in avian species. Here we investigated the effect of chemerin on the food and water consumption and on the body weight in chicken. We studied the effects on the plasma glucose and insulin concentrations and the hypothalamic neuropeptides and AMPK signaling pathway. Female broiler chickens were intraperitoneally injected, daily for 13 days with either vehicle (saline; n = 25) or chemerin (8 μg/kg; n = 25 and 16 μg/kg; n = 25). Food and water intakes were recorded 24 h after each administration. Overnight fasted animals were sacrificed at day 13 (D13), 24 h after the last injection and hypothalamus and left cerebral hemispheres were collected. Chemerin and its receptors protein levels were determined by western-blot. Gene expression of neuropeptide Y (Npy), agouti-related peptide (Agrp), corticotrophin releasing hormone (Crh), pro-opiomelanocortin (Pomc), cocaine and amphetamine-regulated transcript (Cart) and Taste 1 Receptor Member 1 (Tas1r1) were evaluated by RT-qPCR. In chicken, we found that the protein amount of chemerin, CCRL2 and GPR1 was similar in left cerebral hemisphere and hypothalamus whereas CMKLR1 was higher in hypothalamus. Chemerin administration (8 and 16 μg/kg) decreased both food intake and body weight compared to vehicle without affecting water intake and the size or volume of different brain subdivisions as determined by magnetic resonance imaging. It also increased plasma insulin levels whereas glucose levels were decreased. These data were associated with an increase in Npy and Agrp expressions and a decrease in Crh, Tas1r1 mRNA expression within the hypothalamus. Furthermore, chemerin decreased hypothalamic CMKLR1 protein expression and AMPK activation. Taken together, these results support that chemerin could be a peripheral appetite-regulating signal through modulation of hypothalamic peptides expression in chicken.

Diabetes and Obesity-Cumulative or Complementary Effects On Adipokines, Inflammation, and Insulin Resistance

Background: Diabetes and obesity are increasingly significant public health issues. The aim of this study was to evaluate the relationship between adipocytokines (leptin, ghrelin, and chemerin), inflammation (sVCAM1—soluble vascular adhesion molecule 1, sICAM1—soluble intercellular adhesion molecule 1), and insulin resistance in the presence of obesity and diabetes mellitus. Methods: 88 subjects, with a mean age of 61.96 ± 10.15 years, 75% of whom were women, were evaluated (in order to consider different associations between obesity and diabetes, subjects were categorized into four groups). Results: Overall, we found significant correlations between sICAM1-sVCAM1 rho = 0.426 and ghrelin-chemerin rho = −0.224. In the obesity + diabetes group, leptin correlated with sICAM1 rho = 0.786, and sVCAM1 negatively with glycemia/insulin rho = −0.85. Significant differences were found between the groups regarding sVCAM1 (p = 0.0134), leptin (p = 0.0265) and all insulin resistance scores, with differences influenced by the subjects’ gender. In conclusion, although there are currently many unknown aspects of the release and the role of various adipokines, in particular chemerin, its implication in early glucose metabolism dysregulation disorders seems very likely.