Objective To investigate the effect of mild hypothermia on proliferation and differentiation of neural stem cells (NGCs) in hippocampal subgranular zone after traumatic brain injury (TBI) and the underlying mechanism.Methods SD rats were divided into sham-injured group (only left dura mater exposed),hypothermia group (sham injury + mild hypothermia therapy for 72 hours),TBI group (unilateral fluid percussion was used to generate severe TBI),and TBI + hypothermia group (TBI + mild hypothermia therapy for 72 hours) according to the random number table,with 8 rats per group.Hippocampal homogenates or brain tissues were harvested after BrdU (100 mg/kg) was intraperitoneally administered to rats once a day for 7 days postTBI.Expressions of BrdU and double cortin in hippocampal subgranular zone were respectively detected by immunohistochemical or immunofiuorescence staining.Level of Sirt1 (silence information regulatory proteins,Sirt1) in hippocampus was detected by Western blot.Results BrdU-and double cortin-positive cells in rat hippocampal subgranular zone greatly increased at 7 days after TBI in comparison with sham-injured group (P ＜ 0.01).Moreover,BrdU and double cortin in rat hippocampal subgranular zone in TBI + hypothermia group was significantly higherthan that in TBI group [(257.4 ± 34.3) vs (196.4 ± 23.8) ; (346.4 ± 42.2) vs (245.7 ± 33.2),P ＜0.01].Moreover,mild hypothermia reversed TBI-induced over-expression of Sirt1 [(0.62 ± 0.075) vs(1.18 ± 0.11),P ＜ 0.01].Conclusion Mild hypothermia therapy can promote proliferation andneuronal differentiation of NSCs in hippocampal subgranular zone after TBI and the possible mechanismmay relate to the inhibition of over-expression of Sia1.

Objective To simulate the chemical microenvironment of traumatic brain injury (TBI) under mild hypothermia, and investigate the effect of such microenvironment on umbilical cord mesenchymal stem cells (UCMSCs) in vitro.Methods Eighteen SD rats were allocated to shamoperated group, TBI group and mild hypothermia group according to the random number table, with 6 rats per group.Rat models of TBI were made by electric cortical contusion impactor.After systemic mild hypothermia (33℃) for 4 h, brain tissue homogenate extracts were harvested.Polyacrylamide gels mimicking the elastic modulus of brain were manufactured.Human UCMSCs were isolated and cultured on the gels, added with brain tissue extracts from each group.After 24 h, the apoptosis level of UCMSCs was checked, and the medium was changed with normal one.Cell growth and morphological changes in each group were given dynamic observation.Seven days later, cell immunofluorescence was implemented, with the differentiation level of each group estimated.Results Apoptotic rate in TBI group was 73.47％,significantly higher than 10.42％ in sham-operated group (P ＜0.01).While the apoptotic rate was 28.57％ in mild hypothermia group, indicating mild hypothermia significantly reversed the apoptosis of cells in TBI group (P ＜ 0.01).Cell immunofluorescence demonstrated rate of neuronal differentiation of UCMSCs in sham-operated group, TBI group and mild hypothermia group was 16.48％, 2.59％ and 11.83％ respectively.Mild hypothermia resulted in significantly improved neuronal differentiation of UCMSCs after TBI (P ＜ 0.05).Conclusions More apoptosis and lower neuronal differentiation ability are observed in UCMSCs in the chemical microenvironment after TBI.However, mild hypothermia significantly reverses the elevation of apoptosis and restores the neuronal differentiation capacity of UCMSCs after TBI.

Objective To observe the effect of electroacupuncture(EA)on the expression of NKCC1,KCC2 and activation of microglia in spinal dorsal horn of paclitaxel(PTX)-induced neuropathic pain rats and its possible mechanism.Methods Male SD rats were randomly divided into the vehicle group(vehicle),the PTX group,the PTX+EA group and the PTX+sham EA group,with 12 rats in each group.The rat model of PTX-induced neuropathic pain was established by intraperitoneal injection of PTX.After modeling,EA was applied to"Zusanli"and"Yanglingquan"for 7 days in the PTX+EA group.Paw withdrawal threshold and paw withdrawal latency were tested at 2 days before and 1,3,5,7,14 and 21 days after PTX injection.Immunofluorescence and Western blot assay were used to detect expression levels of sodium-potassium-chloride cotransporter 1(NKCC1),potassium-chloride cotransporters 2(KCC2)and microglia markers-ionized calcium binding adapter molecule 1(Iba1)in spinal dorsal horn.Results Compared with the vehicle group,mechanical and thermal hyperalgesia of both hind feet were found in the PTX group,and the expression of NKCC1 and the number of activated microglia in dorsal horn tissue of spinal cord were increased.Compared with the PTX group,mechanical and thermal hyperalgesia were significantly improved in the PTX+EA group at day 14 and 21,and the expression levels of NKCC1 and Iba1 in dorsal horn tissue of spinal cord were decreased.There was no significant difference in KCC2 expression between the four groups.Conclusion Electroacupuncture can effectively relieve paclitaxol-induced neuropathic pain,which may be related to the inhibition of NKCC1 expression and microglia activation in spinal dorsal horn of rats.