Effects of acute salinity stress on osmoregulation, antioxidant capacity and physiological metabolism of female Chinese mitten crabs (Eriocheir sinensis)

The effects of salinity stress (0‰, 15‰, and 30‰) on osmoregulation, antioxidant capacity, physiological metabolism, inflammatory response, and apoptotic factors in Chinese mitten crabs (Eriocheir sinensis, 69.14 ± 2.24 g) were investigated over a short period of time. The results showed that hemolymph osmolality increased significantly with increasing water salinity (P < 0.05), while the activity and mRNA expression of Na+/K+-ATPase in the posterior gills decreased significantly (P < 0.05). After 24–72 h of salinity stress, the activities of antioxidases in the 30‰ group were found to be significantly higher than other groups (P < 0.05). E. sinensis primarily uses the decomposition of carbohydrates to obtain the required energy, while employing proteins and lipids for osmoregulation. Salinity stress induced the production of pro-inflammatory and pro-apoptotic factors in E. sinensis, in addition to upregulating heat shock protein 90 (Hsp90) gene, to enhance resistance. In conclusion, E. sinensis can function as a strong, wide-salt osmoregulator. Carbohydrates and proteins play an important role in regulating the osmolality of E. sinensis. The decomposition of carbohydrates is carried out first to obtain the required energy, followed by utilization of protein. Acute salinity stress can cause oxidative stress and stimulate the production of pro-inflammatory and pro-apoptotic factors. E. sinensis can effectively regulate its antioxidant capacity by modulating the antioxidant system to resist oxidative damage and activate Hsp gene expression, in order to protect the body from adverse environmental damage.