Objective To investigate the effect of high concentration hydrogen gas on neurons in the rat hippocampus CA1 region during global cerebral ischemic/reperfusion injury (GCIR) Methods Four-vessel occlusion was used to establish rat model with GCIR injury. One hundred and five healthy male Sprague-Dawley rats were randomly divided into sham operation group(SH group, n = 15), model group(4-VO group, n = 45) and treatment group(4-VO+H2 group,n = 45). After 72 h and 9 d reperfusion, hippocampal CA1 region pyramidal neurons in every group were detected with Nissle staining , immunohistochemical neuron-specific nuclear protein (NeuN), specific protein antibody microglial cells (Iba1) staining and the relationship of position between neurons and microglia was observed through fluorescence double staining. We used Morris water maze to test the space orientation ability and the learning and memory ability in rats after 9 d reperfusion. Results Compared with those of 4-VO group,the neurons of hippocampus CA1 region were closer to normal in 72 h and 9 d in 4-VO+H2 group and neuron form and the number of neuron survival were increased significantly (P < 0.05);immunohistochemical staining showed that the number of neuron survival in 4-VO+H 2 group was obviously higher than that in 4-VO group (P < 0.05) and the number of microglia in 4-VO group was obviously higher than that in 4-VO+H2 group (P < 0.05). Water maze experiment showed that the swimming time in quadrant Ⅳ in 4-VO+H2 group was longer than that in 4-VO group (P < 0.05). Conclusion Inhalation of high concentration hydrogen gas has prominent protective effect on neurons of rat hippocampal CA1 region during reperfusion. The mechanism may be related with inhibiting the microglia excitation and activation during GCIR.

Objective To explore the protective effect of in-taking high concentration hydrogen gas on neurons and dendritic spines in hippocampus CA1 region of rats after globe cerebral ischemia/reperfusion (I/R) injury and its mechanism.Methods Four-vessel occlusion (4VO) was used to establish the models of global cerebral I/R injury in rats.One hundred and twenty healthy male Sprague-Dawley rats were randomly divided into 3 groups using a random number table:sham-operated group (inhaled 67％ N2 and 67％ O2,n=40),model group (inhaled 67％ N2 and 67％ O2 during reperfusion,n=40),and treatment group (inhaled 67％ H2 and 67％ O2 during reperfusion,n=40).After 72 h,5 and 9 d reperfusion,neuron-specific nuclear (NeuN) protein expression in the pyramidal neurons of the hippocampal CA1 region was detected with immumohistochemical staining and the positive cells were counted.And the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) in serum were tested with colorimetry.Water maze test was used to measure the spatial orientation and memory function and Golgi staining to detect the number of dendritic spines in neurons 9 d after reperfusion.Results (1) Immunohistochemical staining of NeuN results showed that as compared with those in the model group,the neurons ofhippocampus CA1 region were significantly closer to normal with relatively intact structure,and the number of positive neurons was significantly increased in the treatment group 72 h,5 d,and 9 d after reperfusion (P＜0.05).With the reperfusion time being prolonged,the number of NeuN stained positive neurons at different time points of reperfusion in model group was gradually decreased (P＜0.05),and the numeric of the NeuN stained positive neurons at different time points of reperfusion in treatment group was slightly declined without significant difference (P＞0.05).(2) The serum SOD activity in the treatment group was significantly higher than that in the model group and sham-operated group (P＜0.05),while the MDA content in the treatment group was significantly lower than that in model group 72 h,5 d,and 9 d after reperfusion (P＜0.05).And with the reperfusion time being prolonged,the SOD activity at different time points of reperfusion showed no significant difference among the difference groups (P＞0.05).But the MDA content at different time points ofreperfusion between model group and treatment group was significantly different (P＜0.05);with the reperfusion time being prolonged,the MDA content was gradually decreased in both groups.(3) Nine d after reperfusion,water maze test found that the incubation period of treatment group was significantly shorter than that of model group (P＜0.05);the IV quadrant swimming time of space exploration in the treatment group was significantly longer than that in the model group (P＜0.05).(4) Golgi staining showed that the complexity of the neuronal dendrites branch and the number of dendritic spines of neurons in the hippocampal CA1 region of treatment group were increased than those in the model group;high-power oil microscopy indicated that the density of dendritic spines in the treatment group was significantly higher than that in the model group (P＜0.05).Conclusion In-taking of high concentrations hydrogen gas during reperfusion can definitely protect neurons in hippocampal CA1 region after globe cerebral I/R injury,and improve learning and memory function,whose mechanism may be related to hydrogen protecting the structure and function of neurons and dendritic spines,and inhibiting oxidative stress to reduce oxidative damage.

Gel materials have advantages such as comfortable touch, good air permeability, high viscoelasticity, etc., so they are widely used in modern transdermal drug delivery preparations such as patches, gel agents and film agents. With the innovative development of medical materials, many new gel materials with excellent functions have emerged, which has expanded the application scope of transdermal drug delivery preparations and optimized their properties. The classification, properties and application of gel materials in transdermal drug delivery system were reviewed, and the latest research progress was summarized, so as to provide reference for the innovative application of gel materials in transdermal drug delivery system.m.