Two isoforms of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD1 and 11 beta-HSD2) play an important role in regulation of glucocorticoid corticosterone (CORT, the active form in rodents) by the interconversion between CORT and 11-dehydrocorticosterone (11DHC, the biologically inert form). 11 beta-HSD1 is an NADP+/NADPH-dependent oxidoreductase which is mainly expressed in liver and kidney, while 11 beta-HSD2 is an NAD+-dependent oxidase which is predominantly expressed in kidney. The regulation of 11 beta-HSD1 and 11 beta-HSD2 mRNA (Hsd11b1 and Hsd11b2) levels and their activities by IGF-1 was performed in liver, kidney, and testis of IGF-1 knockout mate mice. Real-time PCR showed that Hsd11b1 in liver was decreased while Hsd11b2 mRNA level was decreased in kidney of IGF-1 null mice. 11 beta-HSD1 and 11 beta-HSD2 activities fluctuated with the changes of their respective Hsd11b1 or Hsd11b2 mRNA levels. In conclusion, IGF-1 tissue-specifically regulates Hsd11b1 and Hsd11b2 expression. (C) 2009 Elsevier Inc. All rights reserved.