Vitamin D 3 affects innate immune status of European sea bass (Dicentrarchus labrax L.).

The effects of vitamin D3 dietary administration on certain innate immune parameters on the expression of immune-related genes in head-kidney (HK) and gut were investigated in European sea bass Dicentrarchus labrax. Vitamin D3 (vD3 ) was orally administered to fish in a commercial pellet food supplemented with 0 (control); 3750; 18,750; or 37,500 U kg-1 . Furthermore, gut histology was considered. This study showed a modulation in the activities examined in fish fed with the addition of vD3 . After just 2 weeks of administration, diet supplementation with the vitamin resulted in increased phagocytic ability, while serum peroxidase content was increased in fish fed with all experimental diets after 4 weeks, no significant differences were observed in protease, anti-protease, natural haemolytic complement activities and total IgM level. At gene level, fbl and rbl transcripts were up-regulated in HK in fish fed with the highest concentration of vD3 -supplemented diets after 4 weeks, while in the gut, an up-regulation of hep gene was observed in fish fed with the different doses of vD3 . These results suggest that vD3 may be of great interest for immunostimulatory purposes in fish farms.