Role of vitamin a in the ovary development for female Eriocheir sinensis in the gonadal development stage

Abstract

This study aimed to test the regulatory role of vitamin A in the vitellogenesis of female Eriocheir sinensis. Three diets containing a gradient of vitamin A level (0-control, 8000 and 30,000 IU/kg) were fed to female crabs (74.44 ± 0.81 g) for 90 days. Compared to the vitamin A devoid group, 8000 IU/kg of dietary vitamin A increased the content of hemolymph ecdysone, vitellogenin levels and the gonadosomatic index. The 8000 IU/kg vitamin A level induced vitellogenin (vtg) gene expression in the ovary and hepatopancreas. The vtg gene expression was induced by upregulating retinoid x receptor, ecdysone receptor, ecdysteroid responsive gene E75 and vitellogenin receptor. Lipid accumulation was also improved for ovarian development. Hepatosomatic index and lipid accumulation in the hepatopancreas and ovary were increased by 8000 IU/kg vitamin A supplement relative to the control. The 8000 IU/kg vitamin A diet upregulated the gene expressions in lipid uptake, synthesis and export, but downregulated the genes related to catabolism in the hepatopancreas. Only genes related to lipid uptake were positively influenced by 8000 IU/kg of vitamin A in the ovary. Furthermore, proper vitamin A could improve the health of crabs by enhancing their antioxidant capacity and immunity. In contrast, a negative effect on hepatopancreas antioxidant ability, lipid metabolism and vitellogenesis was found due to an excess vitamin A supplement (30,000 IU/kg) compared to 8000 IU/kg of dietary vitamin A. This study indicates the necessity of vitamin A supplements in formulated diets because they can optimize lipid metabolism and promote vitellogenesis during ovarian development.