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.