The Variation Of NPY、ARGP In Hypothalamus Of Obese Mice And Its Relation With Leptin

OBJECTIVES:The aim of this study was to compare the difference of the NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression and leptin level in obesity and normal mice in different age, and to explore the variation of the NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression and the association with serum leptin level in obese mice.METHODS:60C57/b16mice (male and female in equal) aged6weeks were used throughout the study. Mice were randomized to a standard rodent chow (NC, n=24) or to a high fat diet chow (HFD, n=36). After6weeks on the diet, all mice were randomly divided into two groups,12standard rodent chow mice and11obese mice (DIO,which were chosen from the18HFD mice),were sacrificed for measurement of body length(from top of nose to anus) and body weight. Blood serum was separated by centrifugation and samples stored at-70℃until further use. Abdominal adipose tissues were isolated and fixed in Bouins, solution, paraffin sections were prepared and stained with H&E. Images were visualized using microscope and captured using Digital Camera. The rest12standard rodent chow mice and13obese mice (DIO, which were chosen from the18HFD mice) were sacrificed when they were24weeks old. Blood serum and tissues of the mice were collected as above. Triglyceride(TG) was determined by automatic biochemistry analyzer; Blood glucose concentration (FPG) was determined using glucose oxidase; The fasting plasma insulin (FINS) was tested by radioimmunoassay(RIA); Serum leptin concentration was measured using a Radioimmunoassay Kit (ELISA); HOMA-IR and Lee’s index [(wt(g)1/3*1000/length(cm)] was Calculated. Total RNA for gene expression analysis were isolated from hypothalamus tissues, RT-PCR was used to detect the expression of SH2B1, SOCS3and PTP1B. The real time PCR was performed to detect the expression of SH2B1, SOCS3and PTPlB.RESULTS:①Compared with the NC group, Wt, Lee’s index, FPG, TG, LEP, FINS and HOMA-IR were increased in both12-and24-week-old DIO group.②The levels of LEP, FINS and HOMA-IR in24-week-old DIO group were higher than that of the12-week-old DIO group,but there was no significant difference between12-and24-week-old NC group.③Compared with the NC group, the adipocyte number of DIO group was fewer, area of adipocyte was larger. The adipocyte number was fewer and the adipocyte area was biger with the ageing.④Compared with the NC group, the NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression of12-and24-week-old DIO groups were higher.⑤Compared with the12-week-old DIO group, the NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression were higher than that of the12-week-old DIO group.⑥NPY,AGRP, and NPY-and AGRP-mRNA showed no significant expression difference between the12-week-old NC group and the24-week-old NC group.⑦Shown by Pearson correlation analysis,the level of serum LEP was positively correlated with the expressions of the NPY and the AGRPCONCLUSIONS:①The NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression were higher than that of the normal ones.②In obese mice,the NPY expression,the AGRP expression,and the NPY-and AGRP-mRNA expression showed an increasing trend with ageing while in normal mice, they showde no significant differences with ageing.③The levels of LEP showed an increasing trend with ageing in both obese mice and normal mice.In obese mice the trend is stronger,and the level of serum LEP was positively correlated with the expressions of the NPY and the AGRP.