TERT Are Involved In The Neurogenic Neuroprotection Conferred By Stimulation Of Cerebellar Fastigial Nucleus

Objective To investigate the effects of of TERT in the mechanism(s) of protection elicited by electrical stimulation cerebellar fastigial nucleus before focal cerebral ischemia reperfusion in rats.Methods The study was performed on 120 healthy male Sprague-Dawley rats weighing 280±30g.All rats were randomly divided into four groups:(1)cerebral ischemic-reperfusion(CIR) group, middle cerebral artery obturation was established by suturing the right MCA for 2h, and the rats were randomly divided into three subgroups reperfused for 24h,48h,72h(.2)FNS+CIR group, the FN were stimulated for 1h, 24h later the rats were treated as the same way as the rats in CIR group.(3) cerebellar fastigial nucleus damaging (FND +CIR) group, the rats were given ibotenic acid(IA) injection into the billateral FN. 5 days later, the rats were treated as the same way as the rats in CIR group.(4) FND+FNS+CIR group, the FN were damaging. 5 days later, the rats were treated as the same way as the rats in FNS+CIR group. Each subgroup had 10 rats. After molding, evaluating rat's behavorial scoring and volume of ischemic infarction, and the TUNEL staining was used to facilitate the observation of the quantities of apoptosis in the brain tissues following the various subgroups. Immunohistochemistry method was used to detect the number of the TERT expression positive cells following the different treatment. All data are represented as mean±standard deviation. Results were statistically evaluated by ANOVA followed by the Student-Newman-Keuls test. Differences were considered significant at the level of probability of less than 0.05.Results (1)Result of ischemic infarction volume: It did not differ between subgroups in CIR group nor in FNS+CIR group(P>0.05).Ischemic infarction volume reduced, by nearly 40%, in FNS+CIR subgroup compared to that in CIR subgroup (P<0.05).(2)TUNEL assay result: In CIR 24h subgroup, the focal ischemic infarction production by suturing the right MCA for 2h, localized to the subtotal cortex of frontal lobe and parietal lobe, which nears to the white substance, cortex surrounding hippocampus including basal ganglion, The number of TUNEL-positive cells were 151.6±8.00,P<0.05. In CIR 48h subgroup, the focal extended, not reached to the cortex layer, TUNEL-positive cells reached to the maximal numbers(192±11.21, P<0.05). In 72h subgroup, the focal reached to the cortex layer, TUNEL-positive cells(169.5±7.23, P<0.05) were down regulation, whose number was less than that in CIR 48h subgroup. In every subgroup of FNS group, distribution and diversity tendency of lesions was consistence with that in CIR group, while the number of TUNEL-positive cells were significantly less that in CIR group (P<0.05), especially in FNS+CIR 72h subgroup, only a small amount TUNEL-positive cells can be deserved in the cortex layer. The number of TUNEL-positive cells of FNS+CIR 72h(82.1±5.78) subgroup were significantly less that(169.5±7.23) in CIR 72h subgroup(P < 0.05). In FND+FNS+CIR 24h subgroup, TUNEL-positive cells(158.1±5.86) can be deserved in the cortex layer, reached to the maximal number(s180.9±5.93)in FND+FNS+CIR 48h subgroup, TUNEL-positive cells were down regulation in FND+FNS+CIR 72h subgroup( 170.7±6.73 ) , There had statistical significance between the three subgroups(P < 0.05).Distribution of lesions and the number of TUNEL-positive cells didn't have statistical significance among CIR subgroup, FND+CIR subgroup and FND+FNS+CIR subgroup (P >0.05).(3)Immunohistochemistry method result: the number of TERT-positive cells in all groups, were at most in 24h subgroup, were least in 72h subgroup, the number of TERT-positive cells in 48h subgroup fell between those in 24h and in 72h(P<0.05). The number of TERT-positive cells in FNS+ CIR subgroup were obviously more than that among CIR subgroup, FND+FNS+CIR subgroup and FND+CIR subgroup (P<0.05). The number of TERT-positive cells didn't have statistical significance among CIR subgroup ,FND+CIR subgroup and FND+FNS+CIR subgroup (P>0.05).Conclusion Cerebellar fastigial nucleus electrical stimulation significantly increases the expression of protein TERT , reduces ischemic neuronal death induced by cerebral ischemic–reperfusion in rat. The expression of TERT is likely to play a role in the neuroprotection exerted by FN stimulation.