Changes Of Hydrogen Sulfide/Cystathionine γ-Lyase System In Rats With Insulin Resistance

Objectives:Insulin resistance(IR) means a serious of pathophysiological changes caused by reactivity depression or loss of insulin target tissues and organs. Since normal dose insulin generates less biological effect, more insulin is excreted to compensate. Insulin resistance syndrome (IRS) is the coalescence of hypertension, glycometabolism disorder, visceral obesity, lipid metabolism disorder and other diseases. Most researchers consider IR as the center element and comitant pathogenesy of metabolic disorders composing IRS. As a recently discovered gas signaling molecule, hydrogen sulfide(H₂S) educes vasodilatation activity in physiological condition. Hydrogen sulfide is mainly produced by cystathionine γ—lyase (CSE) of vascular smooth muscle in vascular tissue. Researches found the content and production speed of H₂S were significantly degraded in spontaneously hypertensive rat model. As the expression of CSE gene which was closely related with H₂S production was also depressed, H₂S/CSE system was proved to participate the development of hypertension. However, the changes of H₂S/CSE system in insulin resistance syndrome, its effect on the development of hypertension, whether it is related with insulin resistance are unknown. Our study was based on the rat with insulin resistance established by high-glucose diet. The aim was to explore the changes of H₂S/CSE system, and its effect on the development of hypertension and insulin resistance. Methods:Thirty male Wistar rats weighting (180 ± 18. 5) g were randomly divided into three groups: normal control (NC) , insulin resistant (IR) and NaHS(H₂S donor) treated (NaHS) . Insulin resistant rat model was established by high-glucose diet for 6 weeks. High-glucose diet was composed of glucose 70%, fat 18%, protein 12%, while normal diet was composed of carbohydrate 60%, fat 11%, protein 29%. When insulin resistant model was established, rats in NaHS group were injected with NaHS (56μmol/kg) and rats in other two groups were injected with normal saline once a day for 6 weeks. Body weight (BW) and systolic blood pressure (SBP) of three groups were measured per week. The fasting blood sugar (FBG) , fasting serum insulin (FSI) , cholesterin (TC) , triglyceride (TG) were detected respectively at the end of 6 and 12 weeks, and the insulin sensitive index(ISI) was also calculated. After 12 weeks all the rats were killed, and the transcriptional level of CSE in aorta and the H₂S level in plasma were measured. Datas were analysed using the Statistical Package of the SPSS 13.0. Kolmogorov-Smirnov mormal distribution test and Levene homogeneity test for variance proved all datas fit normal distribution and homoscedasticity. Discriptive datas were given as means±standarddeviation (x|- ±s) . Means of multiple groups were compared by One-WayANOVA analysis and means of two groups were compared by Student-Newman-Keuls test. The P value of less than 0.05 was considered to be significant. Results:1. After 6 weeks compared with NC group, BW (P<0.05) , SBP, FSI, TC, TG of other two groups significantly increased(P<0.01), ISI decreased, and FBG did not change significantly. The indexes of IR and NaSH groups had no significant difference. It was proved that insulin resistant rat model was established.2. After 12 weeks compared with NC group, BW, SBP, FSI, TC, TG of other two groups increased (P<0.01) , ISI decreased, and FBG did not change significantly. Compared with IR group, SBP of NaSH group was lower, but the other indexes had no significant difference.3. The SBP of IR group were higher than NC group after 6 and 12 weeks (P<0001) , and were higher after 12 weeks than 6 weeks (P<0.01) . TheSBP of NaSH group were higher than NC group after 6 and 12 weeks (P<0.01) , but did not change significantly after 6 and 12 weeks. Compared with IR group, the SBP of NaSH group had no significant difference after 6 weeks, but decreased after 12 weeks (P<0.01) .4. The ISI of IR and NaSH groups were lower than NC group after 6 and 12 weeks (P<0.01) , and were lower after 12 weeks than 6 weeks (P<0.05). Compared with IR group, the ISI of NaSH group had no significant difference after 6 weeks and 12 weeks.5. The transcriptional levels of CSE and the H₂S levels of IR group were lower than NC group (P<0.01) . Compared with NC group, the transcriptional levels of CSE of NaSH group were lower, and the H₂S levels of IR group were higher (P<0.01) . The transcriptional levels of CSE(P<0.05) and the H₂S levels (P<0.01) of NaSH group were higher than IR group. Conclusion:1. Since Wistar rats had obesity, hyperlipemia, hyperinsulinemia and lower insulin sensitivity after fed on high-glucose diet (glucose provide 70% of calory) , insulin resistant rats model was established.2. The transcriptional level of CSE in aorta and the H₂S level of insulin resistant rats were significantly lower than normal control rats. 3. After exogenous administration of H₂S donator NaSH, the SBP of insulin resistant rats significantly decreased, the transcriptional levels of CSE and the H₂S levels significantly increased.4. After exogenous administration of H₂S donator NaSH, the obesity, hyperlipemia, hyperinsulinemia and lower insulin sensitivity of insulin resistant rats did not change significantly.