The role of expression imbalance between adipose synthesis and storage mediated by PPAR-γ/FSP27 in the formation of insulin resistance in catch up growth

Background: Catch up growth (CUG) motivated by under-nutrition can lead to insulin resistance (IR) and visceral fat over-accumulation. However, the precise mechanisms on IR induced by adipose tissue changes during CUG remain unresolved. Methods: Experimental rats were divided into three groups: normal chow group, catch up growth group and resveratrol administrated group. The whole experiment was carried out in four stages: 4, 6, 8 and 12 weeks. Peroxisome-proliferator activated receptor gamma (PPAR-gamma) and fat-specific protein 27 (FSP27) expression level in epididymal adipose tissues (EAT) and subcutaneous adipose tissues (SAT) were detected along with other IR indicators. Results: Calorie restriction (CR) significantly increased PPAR-gamma expression in EAT while decreased FSP27 expression. During re-feeding, both of the expression of PPAR-gamma and FSP27 increased, even FSP27 returned to normal level when CUG for 4 weeks. Although PPAR-gamma expression declined slightly at 8 weeks, it was still much stronger than normal chow groups. However, no changes were seen in SAT. Relative insufficiency of FSP27 expression in EAT results in a decrease in lipid storage capacity, causing a series of path physiological changes that led to the formation of IR. Resveratrol inhibited the expression of PPAR-gamma and promoted FSP27 expression, thus fundamentally improving IR. Conclusions: The imbalance between adipose synthesis and storage mediated by PPAR-gamma/FSP27 in the EAT plays a pivotal role in the formation of IR during CUG. Resveratrol can correct fat formation and storage imbalance status by up-regulating FSP27 and down-regulating PPAR-gamma expression level, ameliorating insulin sensitivity.