Cortisol modulates glucose metabolism and oxidative response after acute high temperature stress in Pacific oyster Crassostrea gigas

Cortisol is the main stress hormone that plays crucial roles in energy metabolism and immune response in vertebrates. In the present study, the homologues of 11 beta-hydroxystemid dehydrogenase type 1 (designated Cg11 beta-HSD1) and 5 alpha-reductase 1 (designated Cg5 alpha R1), the key enzymes related to cortisol metabolism, were identified from Pacific oyster Crassostrea gigas. The Cg11 beta-HSD1 harbored a conserved SDR domain, and Cg5 alpha R1 contained a Steroid_dh domain and three transmembrane domains. The mRNA transcripts of Cg11 beta-HSDI and Cg5 alpha R1 were constitutively expressed in all the examined tissues of oysters, with the highest expression level in haemocytes and labial palp, respectively. After acute high temperature stress (28 degrees C), the mRNA expression level of Cg11 beta-HSD1 in hepatopancreas significantly up-regulated at 6 h and 12 h, and that of Cg5 alpha R1 upregulated at 6 h, compared with the Blank group (11 degrees C). The concentration of cortisol and glucose, as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas all significantly up-regulated after acute high temperature stress, while the glycogen concentration in adductor muscle decreased significantly at 6 h and 12 h. After the blockage of Cg11 beta-HSDI with metyrapone, the cortisol concentration and the activities of SOD and CAT significantly decreased after acute high temperature stress, the glucose concentration in hepatopancreas significantly increased at 24 h, and the glycogen concentration in adductor muscle significantly increased at 6 h. These results collectively suggested that cortisol played a crucial role in regulating glucose metabolism and oxidative response in oysters upon acute high temperature stress.