Enzymatic activity of 11β-hydroxysteroid dehydrogenase in rainbow trout (Oncorhynchus mykiss)

We cloned a cDNA encoding 11β-hydroxysteroid dehydrogenase (11β-HSD) from rainbow trout testis and head kidney. Homology search suggested that the rainbow trout 11β-HSD (rt11β-HSD) homologue was more like mammalian 11β-HSD type 2 than type 1. In order to investigate the enzymatic activity of rt11β-HSD, we conducted transient transfection assays using HEK293 cells. The results demonstrated that rt11β-HSD is predominantly a 11β-dehydrogenase, a homologue of mammalian 11β-HSD type 2. The ability of rt11β-HSD to convert cortisol to cortisone and the patterns of seasonal changes in the rt11β-HSD transcript levels in ovary and testis supports the possibility of a role for rt11β-HSD in protecting gonads from circulating cortisol