Effect of hydrogen sulfide combined with mild hypothermia on cerebral ischemia-reperfusion in rats

Objective To evaluate the effect of hydrogen sulfide combined with mild hypothermia on cerebral ischemia-reperfusion (I/R) injury in rats. Methods Eighty male SD rats, aged 3 months, weighing 250-300 g, were randomly divided into 5 groups ( n = 16 each): sham operation group (group S), cerebral I/R group,mild hypothermia group (group M), sodium hydrosulfide group (group NaHS) and NaHS + mild hypothermia group (group NM). In group I/R, M, NaHS and NM, cerebral I/R was induced by occlusion of 4 vessels (cauterization of bilateral vertebral arteries and 15 min occlusion of bilateral common carotid arteries) followed by reperfusion. In group NaHS and NM, intraperitoneal NaHS 14 μmol/kg was injected immediately after reperfusion, while the equal volume of normal saline was injected in the other three groups. At the same time, the rectal temperature was reduced to 32-33 ℃ within 15 min, lasting for 6 h, in group M and NM, while it was maintained at 36-37 ℃by physical method in other groups. Twelve rats of each group were sacrificed after 6 h of reperfusion, and then the hippocampus was removed for determination of the content of H2 S by using spectrophotometer and the expression of p-CREB and BDNF mRNA by using Western blot and RT-PCR respectively. Four rats in each group were sacririced after 72 h of reperfusion and then the hippocampus was removed for microscopic examination. Results The cerebral I/R injury was attenuated in group M, NaHS and NM compared with group I/R, with the slightest injury in group NM. The H2S content was significantly higher in group I/R, M, NaHS and NM than in group S, and in group NaHS and NM than in group I/R and M. The expression of p-CREB and BNDF mRNA was significantly higher in group I/R, M, NaHS and NM than in group S, and in group M, NaHS and NM than in group I/R. The BDNF mRNA expression was significantly higher in group NM than in group M and NaHS. There was no significant difference in the H2S content and the expression of p-CREB and BNDF mRNA between group NaHS and M.Conclusion Hydrogen sulfide combined with mild hypothermia can attenuate cerebral I/R injury by up-regulating the expression of p-CREB and BDNF mRNA in hippocampus in rats. Key words: Hydrogen sulfide; Hypothermia, induced; Reperfusion injury; Brain