Effects of crustacean hyperglycemic hormone (CHH) RNA interference on regulation of glucose metabolism in Litopenaeus vannamei after ammonia-N exposure.

To unveil the adaptation of Litopenaeus vannamei to elevated ambient ammonia-N, crustacean hyperglycemic hormone (CHH) was knocked down to investigate its function in glucose metabolism pathway under ammonia-N exposure. When CHH was silenced, haemolymph glucose increased significantly during 3-6 h, decreased significantly during 12-48 h, and recovered to the control groups' level at 72 h. After CHH knockdown, DA contents reduced significantly during 3-24 h, which recovered after 48 h. Besides, the expressions of GC and DA1R in the hepatopancreas decreased significantly, while DA4R increased significantly. Correspondingly, the contents of cAMP, cGMP and DAG and the expressions of PKA, PKG, AMPKα and AMPKγ were significantly downregulated, while the levels of PKC and AMPKβ were significantly upregulated. The expressions of CREB and GLUT2 decreased significantly, while GLUT1 increased significantly. Moreover, glycogen content, glycogen synthase and glycogen phosphorylase activities in hepatopancreas and muscle were significantly increased. Furthermore, the levels of key enzymes HK, PK and PFK in glycolysis, rate-limiting enzymes CS in TCA, and critical enzymes PEPCK, FBP and G6P in gluconeogenesis were significantly decreased in hepatopancreas. These results suggest that CHH affects DA, and then they affect their receptors respectively to transmit glucose metabolism signals into the hepatopancreas of L. vannamei under ammonia-N stress. CHH acts on cGMP-PKG-AMPKα-CREB pathway through GC, and CHH affects DA to influence cAMP-PKA-AMPKγ-CREB and DAG-PKC-AMPKβ-CREB pathways, thereby regulating GLUTs, inhibiting glycogen metabolism and promoting glycolysis and gluconeogenesis. This study contributes to further understand glucose metabolism mechanism of crustacean in response to environmental stress.