Differential effects of adrenocorticotropic hormone on human and mouse adipose tissue

Adrenocorticotropic hormone (ACTH) induces lipolysis in a dose-dependent fashion in rodent adipose tissue and adipocytes in vitro. The role of ACTH on lipolysis in human adipose tissue is less clear, however. In this study, we address the hypothesis that ACTH induces lipolysis in human adipose tissue. We used ex vivo organ culture to examine lipolysis in human and mouse adipose tissue. Adipose tissue fragments suspended in culture medium and human ACTH, isoproterenol (positive control), or insulin (negative control) was added in varying concentrations. Lipolysis was measured using glycerol appearance. ACTH receptor mRNA expression was assessed using reverse-transcription polymerase chain reaction (RT-PCR). In mouse adipose tissue, ACTH induced lipolysis in dose-dependent manner; 100 pmol/l ACTH induced 67+/-19% of isoproterenol-stimulated lipolysis and 500 pmol/l ACTH: 86+/-13%. In contrast, human adipose tissue shared no significant response to 100 pmol/l ACTH; ACTH was associated with 9+/-6% and 500 pmol/l of ACTH, 8+/-6% of isoproterenol-stimulated lipolysis. ACTH receptor mRNA was present in mouse adipose tissue, but undetectable in human adipose tissue. These results suggest lipolysis regulation differs between human and mouse adipose tissue in response to ACTH.