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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

[Effect of resveratrol on body composition in adult catch-up growth rats and its mechanism].

OBJECTIVE: To observe the effects of resveratrol on body composition in adult catch-up growth rats and to explore the possible mechanism. METHODS: Eight-week-old male SD rats were randomly divided into 6 groups: normal controls for 4 weeks (NC4) group, caloric restriction for 4 weeks (R4) group, calorie restriction meanwhile resveratrol treatment for 4 weeks (R4E) group, normal controls for 12 weeks (NC12) group, catch-up growth (CUG) group and catch-up growth meanwhile resveratrol treatment for 8 weeks (CUGE) group. At the end of the four-week and twelve-week experimental period, the body weight, muscle and fat content of trunk and whole body, the ratio of trunk to whole body fat were detected, and at the end of twelve-week experimental period, the expression of SIRT1 in skeletal muscle and epididymal adipose tissue, and the expression of PPARγ in epididymal adipose tissue were detected. RESULTS: Compared with NC12 group, the fat content of trunk and whole body and trunk to whole body fat ratio in CUG group were increased significantly, along with the expression of PPARγ in epididymal adipose tissue was increased significantly (P＜0.05), while the muscle content of trunk and whole body, the expression of SIRT1 in skeletal muscle and epididymal adipose tissue in CUG group were decreased significantly compared with NC12 group (P＜0.05 or P＜0.01); compared with CUG group, oral administration of resveratrol distinctly reduced the body fat content and trunk to whole body fat ratio in the CUGE groups, and the expression of PPARγ in epididymal adipose tissue of CUGE group was also significantly decreased (P＜0.05). Meanwhile, the muscle content and the expression of SIRT1 in skeletal muscle and epididymal adipose tissue in CUGE group were significantly increased compared with the CUG group (P＜0.05). CONCLUSION: Resveratrol can decrease body fat content, increase muscle content and improve abdominal fat accumulation in adult catch-up growth rats, and its mechanism may be associated with increasing SIRT1 expression in skeletal muscle and visceral adipose tissue, decreasing PPARγ expression in visceral adipose tissue.