The phosphodiesterase inhibitor IBMX suppresses TNF-alpha expression in human adipocyte precursor cells: a possible explanation for its adipogenic effect.

Tumor necrosis factor-alpha (TNF) is known to inhibit fat cell development in vitro and to be expressed in adipose tissue suggesting that it may act as an auto-/paracrine regulator of adipose tissue mass in vivo. We demonstrate here that endogenous TNF-mRNA expression of cultured human preadipocytes and adipocytes is suppressed by the unspecific phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), which is frequently used to trigger the differentiation process. As assessed by the measurement of glycerophosphate dehydrogenase, IBMX stimulated the differentiation of human preadipocytes in a dose dependent manner up to threefold but remained ineffective when cells were simultaneously treated with 1 nM TNF. These results suggest that the adipogenic effect of IBMX is mediated by suppression of endogenous TNF production.