[Relationship between perirenal adipose tissue neuropeptide Y and insulin resistance in nutritional transition model]

To observe the changes of neuropeptide Y(NPY) expression in perirenal adipose tissue and its relationship with insulin resistance in the nutritional transition models of refeeding after calorie restriction.

SPF Male SD rats, aged 8 weeks, were randomly divided into normal chow group and refeeding with normal chow after calorie restriction for 4 weeks group. NPY gene expression in perirenal adipose tissue were detected by real-time quantitative PCR at the end of 4 and 12 weeks, along with fasting plasma glucose, fasting serum lisulin, free fatty acids and average glucose infusion rate(GIR_(60-120)) of hyperinsulinemic-euglycemic clamp test for 60-120 minutes. NPY gene mRNA expression in perirenal adipose tissue was detected by real-time quantitative PCR. And the relationship between NPY gene expression and insulin resistance was detected by Spearman correlation analysis.

The expression level of NPY gene in perirenal adipose tissue in caloric restriction for 4 weeks group was significantly increased by calorie restriction(P<0. 01). After refeeding, the expression level of NPY gene in refeeding with normal group was still slightly increased, which was significantly higher than that in normal group at the end of the experiment(P<0. 01). The levels of fasting plasma glucose and fasting insulin in caloric restriction for 4 weeks group decreased slightly, GIR_(60-120) increased slightly, but there were no statistical differences compared with normal group(P>0. 05), but free fatty acid levels increased significantly(P<0. 01). After refeeding, the levels of fasting insulin, free fatty acid in refeeding with normal group increased significantly, GIR_(60-120) decreased evidently(P<0. 01), but the changes of fasting blood glucose were not obvious. The result of stepwise regression showed that the expression level of NPY gene in perirenal adipose tissue was closely related to GIR_(60-120) and fasting insulin, with R values of-0. 816 and 0. 789 respectively(R~2=0. 892, P<0. 01). The result of correlation analysis showed that in the 4-week group, the mRNA expression level of NPY gene in perirenal adipose tissue was closely related to GIR_( 60-120)、fasting insulin and free fatty acid, with R values of-0. 765, 0. 716 and 0. 657 respectively(P<0. 01). In the 12 week group, the mRNA expression level of NPY gene in perirenal adipose tissue was closely related to GIR_(60-120), fasting insulin and free fatty acid, with R values of-0. 853, 0. 622 and 0. 608 respectively(P<0. 01).

The mRNA expression of NPY gene in perirenal adipose tissue was closely related to indicators of insulin resistance. It is an important factor affecting insulin sensitivity.