Difference Analysis of Liver Metabolic Response Between Diploid and Triploid Rainbow Trout Oncorhynchus mykiss Under Fishing Stress

To elucidate the effects of fishing stress on the liver glucose metabolism of both diploid and triploid female rainbow trouts as well as differences in their stress response,blood and liver tissues were collected from 0 h to 24 h after the fishing stress.Blood indexes,such as the levels of white blood cells and red blood cells,cortisol,glucose and lactic acid,as well as activities of key enzymes of the glucose metabolism in the liver,were measured.Furthermore,the mRNA expressions of glucocorticoid receptors and enzymes related to energy metabolism were assessed.The results showed that fishing stress exerted significant effects on blood physiological and biochemical indexes and liver glucose metabolism.Differences were found between diploid and triploid female rainbow trouts in the liver glucose metabolism pathway,as well as the level and performance during stress.The basic glucose metabolism intensity of the triploid liver was higher than that of the diploid liver;however,the hepatic glycogen reserve was lower in the triploid liver.After fishing stress,triploid trouts entered the immunosuppressive state earlier than diploid trouts.Triploid trouts also showed an earlier and stronger stress reaction than diploid trouts,while their energy allocation ability and immune recovery ability were weaker than those of diploid trouts.These results showed that the regulatory ability of diploid female rainbow trouts in response to fishing stress was better than that of triploid trouts.