Tissue distribution and expression analyses of Megalobrama amblycephala gr in stress

In order to understand the biological function of glucocorticoid receptors (GRs) of Megalobrama amblycephala, we explored the expression characteristics of grs in different tissues and the expression changes of grs and some function genes in the recovery process after stress. Results show that the gr1 was highly expressed in gill, spleen and head kidney, while gr2 was highly expressed in pituitary, liver, intestinal, and so on. During the recovery process, on HPI axis, the expression of gr1 had fluctuations, gr2 significantly up-regulated at the 0 h, and the value of gr1/gr2 was gradually increasing in hypothalamus. The expression of gr1 and gr2 all rose first and then decreased, gr1/gr2 value reached the peak at 2 h in pituitary. The expression of gr1 had fluctuations, whereas gr2 had a low expression at 0 h and 2 h compared with the other time points, gr1/gr2 value gradually decreased in head kidney. In liver, gr1 rose in the early time (0 h and 2 h), and gr2 presented a fluctuating situation, and there was a tendency to reduce the the value of gr1/gr2. At the similar time point the expression of pepck peaked. In gills gr1 rose first, and then decreased, while the expression of gr2 was subdued in the early time (0 h and 2 h), gr1/gr2 value maintained at a large value during 2-8 h, while the occ expression peaked at 2 h. In skin gr1 and gr2 rose significantly in 2 h, gr1/gr2 in 2-8 h also maintained at a large value, and the occ expression rose first and then decreased. Histology research shows that gill filament was hyperplasia, lymphocyte-like cells increased kidney tissues, while other organizations examined had no obvious pathological changes. All the results indicate that GRs have a complex regulatory mechanism in the stress, and the histological analysis shows that the risks of pathological changes come from the stress.