Hydrogen Sulfide Inhibits The Apoptosis Of Hippocampal Neurons Through The JNK Pathway To Improve The Cognitive Function Of H-type Hypertensive Rats

Objective:This study was aimed to investigate the role and regulatory mechanism of the hydrogen sulfide?H₂S?in rat model of hypertension with elevated plasma homocysteine induced by L-methionine water feeding SHR rats via regulating the activity of JNK signaling pathway.Methods:All the 25 adult male SHR rats were fed with 1%Methionine?10g/L,dissolved in fresh water?for 6 weeks.Then 3 groups were randomly divided into after successful modeling:Model group?n=8?,Model+H₂S group?n=8?and Anisomycin group?n=9?.Model+H₂S produced by intraperitoneal injection of H₂S?56umol/kg/d,once a day?for 4 weeks,Anisomycin group simultaneously intraperitoneal injection of H₂S?56umol/kg/d,once a day?and Anisomycin?5mg/kg,once a day,prepared with PBS dissolve into 20 mg/ml liquid stored away from light and saved in the-20?refrigerator?for 4 weeks.The Model group were injected the same volume of saline for 4 weeks.At the same time,14 adult male WKY rats were all fed with ordinary drinking water for6 weeks and randomly divided into two groups:the normal Control group?n=7?and the Control+H₂S group?n=7?.The Control+H₂S group was intraperitoneally injected with H₂S?56umol/kg/d,once a day?,and the Control group were injected the same volume of saline.Blood pressure of rats were measured by non-invasive blood pressure measurement system.Plasma homocysteine was detected by cyclic enzyme assay.The cognitive functions of rats were evaluated by Y-maze test and novel object recognition?NOR?test.Morphological changes of hippocampal neurons were observed by HE staining.Tunel staining was used to observe hippocampal neurons apoptosis.Western blotting was used to detect the expression levels of JNK?caspase3?caspase9?Bax?Bcl-xl and other proteins.Results:1.Compared with WKY rats,the blood pressure of SHR rats significantly increased?P<0.05?.2.Compared with WKY rats,the plasma homocysteine level of SHR rats was significantly increased?P<0.05?.3.Compared with the Control group,the alternation performance of Y-maze and the new object discrimination index in the Model group decreased significantly?P<0.05?.Compared with the Model group,the Model+H₂S group markedly increased the alternation performance in Y-maze test and discrimination index in NOR test?P<0.05?.Compared with the Model+H₂S group,the alternation performance of Y-maze in Anisomycin group decreased again?P>0.05?,and discrimination index in NOR test decreased significantly?P<0.05?.Control and Control+H₂S don't have a statistically significant difference in alternation performance and discrimination index.4.HE staining showed that hippocampal neurons in the Model group were more disordered and the cell morphology were more diverse than those in the Control group.Hippocampal neurons in the Model+H₂S group were relatively orderly and more regular than those in the Model group.Compared with the Model+H₂S group,the hippocampal neurons in the Anisomycin group were disordered and the cell morphology were irregular.5.Compared with the Control group,Tunel staining showed significantly increased apoptosis of hippocampal neurons in the Model group.The apoptosis of hippocampal neurons in Model+H₂S group was significantly improved compared with that in Model group.Compared with Model+H₂S group,the apoptosis of hippocampal neurons in Anisomycin group was significantly increased.6.Compared with the Control group,the expressions of JNK,caspase3,caspase9,Bax,Bcl-xl were significantly increased in Model group.The expression levels of JNK,caspase3,caspase9,Bax,Bcl-xl in the Model+H₂S group were significantly lower than those in the Model group?P<0.05?,while the expression level of JNK in the Anisomycin group were significantly higher than those in the Model+H₂S group?P<0.05?,but the expression levels of caspase-3,caspase-9,Bax and Bcl-xl were not statistically significant?P>0.05?.The expression levels of JNK,caspase3,caspase9,Bax and Bcl-xl in the Control and Control+H₂S groups showed no significant difference?P>0.05?.Conclusion:H₂S can improve the cognitive function of H-type hypertensive rats,and its mechanism may be related to the inhibition of JNK signal pathway to reduce the apoptosis of hippocampal neurons.