Intermittent high glucose exacerbates the aberrant production of adiponectin and resistin through mitochondrial superoxide overproduction in adipocytes.

Hypoadiponectinemia and hyperresistinemia may be important in mediating signals from adipocytes to insulin-sensitive tissue and vasculature. However, the mechanism that mediates the aberrant production of adipokines remains poorly understood. In this study, we have investigated the effect of intermittent high glucose on the expression of adiponectin and resistin, and the production of 8-hydroxydeoxyguanosine (8-OHdG) and nitrotyrosine in the adipocytes, either in the presence or in the absence of Mn(III) tetrakis(4-benzoic acid) porphyrin chloride (MnTBAP) or thenoyltrifluoroacetone (TTFA). 3T3-L1 adipocytes were incubated for 72 h in media containing different glucose concentrations: 5 mmol/l, 20 mmol/l, 5 mmol/l alternating with 20 mmol/l glucose, with or without MnTBAP and TTFA. We measured the expression of resistin and adiponectin. The production of nitrotyrosine and 8-OHdG as oxidative stress parameter was measured. Both constant and intermittent high glucose significantly suppressed the expression and secretion of adiponectin, and increased expression and secretion of resistin in mature adipocytes compared to normal glucose conditions. However, these effects were significantly greater under intermittent high glucose conditions compared to constant high glucose. The levels of nitrotyrosine and 8-OHdG were significantly elevated under both intermittent and constant high glucose conditions, the effect being greater under intermittent high glucose. In addition, the antioxidants MnTBAP or TTFA reversed the aberrant production of adiponectin and resistin, as well as overproduction of nitrotyrosine and 8-OHdG in adipocytes induced by constant or intermittent high glucose. Intermittent high glucose exacerbates the aberrant production of adiponectin and resistin through reactive oxygen species overproduction at the mitochondrial transport chain level in adipocytes, indicating that glycemic variability has important pathological effects on the secretion of adipokines.