Hydrogen sulfide and mild hypothermia can selectively activate synaptic NMDARs and trigger the CREB signaling pathway / 医学研究生学报

ABSTRACT

Objective Research has indicated that hydrogen sulfide(H2S) can regulate the function of N-methyl-D-aspartate re-ceptors(NMDARs) in the brain, but its effect on brain resuscitation requires further investigation.The study was to speculate the effect of H2 S on brain resuscitation as well as the underlying mechanism of neuroresuscitation by investigating the effects of hydrogen sulfide and hypo-thermia on the expression of NR2A, NR2B and phospho-cAMP response element binding protein (p-CREB) of NMDARs in the hippocampus after global cerebral ischemia following by reperfusion. Methods 100 male SD rats were randomly divided into five groups(n=20)sham operation group, model group, mild hypothermia group, NaHS group, NaHS combined mild hypothermia group.Pulsinelli-Brierley four-ves-sel occlusion method was induced to build the injury rat model by reperfusion after global cerebral ischemia .After 15 minutes'ischemia, im-mediate injection of 14μmol/kg NaHS was performed intraperitoneally on NaHS group and NaHS combined mild hypothermia group , while skin cooling(rectal temperature=32-33℃) was done on mild hypothermia group and NaHS combined mild hypothermia group .6 hours late,r hip-pocampus were extracted from rat heads.Respectively, spectrophotometer was applied to measure the content of H2S, Western blot for the expres-sions of NR2 A,NR2 B and pC-REB, and RTP-CR for mRNA level of brain derived neurotrophic (BDNF). HE staining was also performed on brain tissues 72hours after reperfusion on 4 rats from each group to evaluate the pathological changes of pyramidal neurons in CA1 region. R esul ts The content of H 2 S increased in each of the four groups after ischemia-reperfusion compared with sham operation group ( 15.2 ±2.0 nmol/g) (P0.05).The gray values of NR2A and NR2B in each group increased compared with sham operation group(P1 in NaHS group and NaHS combined mild hy-pothermia group.Compared with the expression of p-CREB(0.55 ±0.06) in model group, there were significant increases in mild hypother-mia group(0.99 ±0.15), NaHS group(1.05 ±0.12), NaHS combined mild hypothermia group(1.02 ±0.15)(P<0.05).Compared with the expression of BNDF mRNA(0.83 ±0.12) in model group, there were significant increases in mild hypothermia group (1.11 ±0.13), NaHS group(1.27 ±0.16), NaHS combined mild hypothermia group(1.35 ±0.16)(P<0.05).In comparison to model group, there were signifi-cant alleviation in the injury of pyramidal neurons in hippocampal CA1 region in mild hypothermia group, NaHS group, NaHS combined mild hypothermia group, with the best effect in NaHS combined mild hypothermia group . Conclusion Hydrogen sulfide combined mild hypo-thermia can selectively activate synaptic NMDA receptors and trigger the prosurvival CREB signaling pathway to exert brain resuscitation .