| Objective:To investigate the effect of nicotine on the anti-inflammatory mechanism of ischemic cognitive impairment through the JAK2-STAT3 signaling pathway.Methods:The endothelin-1?Endothelin-1,ET-1?was injected into the left thalamus area of rats by stereotaxic device,and the focal ischemic cognitive impairment model was established.After the operation were treated with nicotine?1.5mg/kg/d?,nicotine?1.5mg/kg/d?+Dihydro-beta-erythroidine?DH?E??3 mg/kg/d?,AG490?3 mg/kg/d?,nicotine?1.5mg/kg/d?+AG490?3 mg/kg/d?and intraperitoneal injection of normal saline.Nicotine group,nicotine+DH?E group,AG490 group,nicotine+AG490 group and ischemic group rats were continuously intervened for 9 days.The Morris water maze test was used to detect the cognitive function of rats in fourth day after operation.After the end of the study,2-[18F]-A-85380 Micro PET imaging was performed immediately,and the number of nAChRs receptors in different brain regions was evaluated.The effects of nicotine on the alpha 4 beta 2 nAChRs receptor subunit and JAK2-STAT3 signaling pathway in the thalamus of rats were detected by Real-time PCR.The effects of nicotine on alpha 4 beta 2 nAChRs receptor subunits,inflammatory factors and JAK2-STAT3 signaling pathway were detected by Western blot technique.Results:Morris water maze navigation test,the escape latency of all groups of rats with experimental days were increased in fifth days shortened,the escape latency was 60.50±42.88?ischemia group?,26.46±24.93?nicotine group?,48.83±37.19?nicotine+DH?E group?,46.92±39.08?nicotine+AG490 group?,49.83±33.14?AG490 group?.The spatial learning and memory ability of rats with ischemia group were significantly higher than those of nicotine treated rats,there were statistically significant differences in escape latency?p<0.05?;there was no significant difference between nicotine+DH?E group,nicotine+AG490 group and AG490 group compared with ischemia group?p>0.05?.Morris water maze experiment in space exploration,and memory ability of nicotine group rats compared with ischemia group rats have obviously improved,removed the platform,according to the learning and memory of rats before finding the platform,through the platform of the original record number and placed through the platform quadrant time.The times of cross platformof ischemiagroup,nicotinegroup,nicotine+DH?Egroup,nicotine+AG490 group and AG490 group were?2.33±0.94?5.50±2.06?2.17±2.41?2.67±1.70?2.83±1.34?.Statistically significant differences between nicotine group rats and ischemia group rats?p<0.05?;in the target quadrant duration,nicotine group rats and ischemia group rats were statistically significant difference?p<0.05?;there was no statistically significant differences between nicotine+DH?E group,nicotine+AG490 group and AG490 group compared with ischemia group?p>0.05?.The rat brain Micro PET imaging,the imaging at 120 min after injection of2-[18F]-A-85380,the specific value of SUVave left thalamus/SUVave cerebellum,SUVave whole brain/SUVave cerebellumve cerebellum in nicotine group and nicotine+AG490 group were higher than the ischemia cognitive dysfunction rats.While in nicotine+DH?E group and AG490group had no significant difference compared with the ischemia cognitive dysfunction rats.In the ischemia group,nicotine group,nicotine+DH?E group,nicotine+AG490group and AG490 group,the specific value of SUVave left thalamus/SUVave cerebellumve cerebellum were2.38±0.08,2.82±0.13,2.43±0.11,2.80±0.06,2.31±0.04;SUVave whole brain/SUVave cerebellumwere 1.60±0.06,1.73±0.09,1.59±0.06,1.76±0.04,1.60±0.04.Real-time PCR results showed that the expression of alpha 4 nAChR,beta 2nAChR,JAK2 and STAT3 mRNA in the left thalamus of nicotine group was significantly higher than that in ischemia group?0.75±0.16,0.86±0.11,1.01±0.07,1.18±0.05?.The expressions of JAK2 and STAT3 mRNA in the left thalamus of nicotine+DH?E group,nicotine+AG490 group and AG490 group were lower than those in the nicotine group,but there was no significant difference compared with ischemia group.The expression of alpha 4 nAChR,beta 2 nAChR mRNA in nicotine+AG490 group was still significantly higher than those in ischemia group rats?0.74±0.07,0.82±0.03?,compared with the nicotine group rats had no significant difference;In nicotine+DH?E group and AG490 group rats,the expression of alpha 4nAChR,beta 2 nAChR mRNA was significantly lower than that of nicotine and nicotine+AG490 group,compared with ischemia group rats had no significant difference.It is indicated that nicotine activates the JAK2-STAT3 signaling pathway by up regulation of alpha 4 beta 2 nAChRs.Western blot results showed that the expression of beta 2 nAChR,p-JAK2 and p-STAT3 protein in the left thalamus of nicotine group was significantly higher than that in ischemia group?2.05±0.12?0.95±0.03?1.12±0.02?.The expression of p-JAK2and p-STAT3 protein in the left thalamus of nicotine+DH?E group,nicotine+AG490group and AG490 group were lower than that in the nicotine group,but there was no significant difference compared with ischemia group.In nicotine+AG490 group,the expression of beta 2 nAChR protein was significantly higher than that in the ischemia group?1.91±0.03?,compared with the nicotine group rats had no significant difference;In nicotine+DH?E group and AG490 group,beta 2 nAChR protein expression was significantly lower than the nicotine group and the nicotine+AG490group,compared with ischemia group rats had no significant difference.The expression of IL-1 beta and IL-6 protein in the left thalamus of nicotine group decreased compared with the ischemic group?p<0.05?,while the relative expression of inflammatory factors in the left thalamus of nicotine+DH?E group,nicotine+AG490 group and AG490 group was not significantly different from those in the ischemic group.Conclusion:In rats with ischemic cognitive impairment,nicotine further activates the JAK2-STAT3 signaling pathway to inhibit the expression of inflammatory factors by activating the alpha 4 beta 2 nAChRs. |
PDF Full Text Request