Effect of Ca²⁺ homeostasis on energy metabolism and detoxification metabolism in Litopenaeus vannamei exposed to ammonia stress

To reveal the regulatory role of Ca²⁺ homeostasis in shrimp's ammonia nitrogen tolerance, we investigated the effects of ammonia stress on the energy metabolism and detoxification metabolism of Litopenaeus vannamei. We divided the shrimps into six groups, which were injected with specific siRNA to suppress the expression of Ca²⁺ stability regulation genes SERCA (si-SERCA group), MCU (si-MCU group), and IP₃R (si-IP₃R group), a group that received no substance (NI group), a group injected with phosphate-buffered saline (PBS group), and a group injected with non-coding RNA (NC group) as the control group. Then, we exposed them to a total ammonia concentration of 11.3 mg·L⁻¹ for 24 h under ammonia stress conditions, and measured the expression levels of energy metabolism-related genes and detoxification metabolism-related genes. The results show that the expression levels of energy metabolism-related genes FAS, ACC, CPT-1, PK, PFK and HK in si-SERCA group, si-MCU group and si-IP₃R group showed a significant increase compared with the control group (p<0.05). The expression levels of detoxification metabolism-related genes GS, GDH and GST in si-SERCA group were significantly higher than those in the control group at 6–24 h after stress (p<0.05). The expression level of GDH in si-MCU group was significantly higher than that in the control group at 6–24 h after stress, and the expression level of GST was significantly higher than that in the control group at 6–18 h after stress (p<0.05). The expression levels of GS, GDH and GST in si-IP₃R group were significantly higher than those in the control group, and the expression level of GST was significantly higher than that in the control group at 6–24 h after stress (p<0.05). Furthermore, the expression of energy metabolism-related genes was significantly positively correlated with the expression of detoxification metabolism-related genes (p<0.05). The results indicate that under ammonia stress, inhibiting the expression of genes related to Ca²⁺ homeostasis significantly increases the energy metabolism and detoxification metabolism levels of shrimp, thereby enhancing their ammonia tolerance.