ABSTRACT
Objective To investigate the roles of phosphorylated glycogen synthase kinase 3β (pGSK3β) and phosphorylated signal transducer and activator of transcription 3 (pSTAT3) in hypoxic preconditioning-induced neuroprotection against ischemic brain injury in rats.Methods Sixty SD rats were randomly divided into a sham operation group,a cerebral ischemia group,and a hypoxia preconditioning group (n =20 in each group).A model of middle cerebral artery occlusion (MCAO) was induced by the modified suture method.Before the preparation of MCAO model,the rats in the hypoxia preconditioning group were put into a hypobaric oxygen chamber at a simulated altitude of 5 000 m (pressure:0.53 × 105 kPa;partial pressure of oxygen:81 mmHg;1 mmHg =0.133 kPa),3 h a day for 5 days.At 24 h after MCAO modeling,the rats were subjected to neurobehavioral score (n =6) and cerebral infarction volume measurement (n =6).Immunohistochemical staining was used to detect the expression levels of neuronal nuclei (NeuN) and pGSK3β (Ser9) (n=7).Western blot was used to detect the expression levels of pGSK3 β (Ser9) and pSTAT3 (Tyr705) in the ischemic cortex (n =7).Results The neurological deficit score (1.833 ±0.408 vs.2.667 ± 0.516;t =3.101,P=0.011) and cerebral infarction volume (18.137％ ± 0.801％ vs.24.125％ ± 0.694％;t =13.840,P＜ 0.001) in the hypoxia preconditioning group were significantly lower or smaller than those in the cerebral ischemia group.Immunohistochemical staining showed that the numbers of NeuN positive cells in the cerebral ischemia group and the hypoxia preconditioning group were significantly less than that in the sham operation group (48.000 ± 1.414/high power field [HPF],124.833 ± 3.061/HPF,and 213.500 ± 2.429/HPF;F =7 150.550,P ＜ 0.001),the hypoxia preconditioning group was significantly more than the ischemia group (P ＜0.001);the numbers of pSTAT3 positive cells in the cerebral ischemia group and the hypoxia preconditioning group were significantly higher than that in the sham operation group (57.667 ± 1.366/HPF,29.167 ± 1.941/HPF and 3.500 ± 1.049/HPF;F =1 962.649,P ＜0.001),and the hypoxia preconditioning group was significantly less than the ischemia group (P ＜0.001).Western blot analysis showed that the expression levels of ischemic cortical pGSK3β and pSTAT3 in the cerebral ischemia group and the hypoxia preconditioning group were significantly higher than those of the sham operation group (pGSK3 β:2.336 ± 0.102,0.876 ± 0.196 and 0.440 ± 0.012;F =1 610.826,P ＜ 0.001;pSTAT3:8.368± 0.230,4.883± 0.123 and 0.595± 0.138;F=4018.051,P＜0.001),the hypoxia preconditioning group were significantly lower than the ischemia group (all P ＜0.001).Conclusions Hypoxia preconditioning has neuroprotective effect for ischemic brain injury in rats.It may be associated with the down-regulation of the expressions of pGSK3 and pSTAT3.
ABSTRACT
BACKGROUND:Fisher-Lewis rat kidney transplant models are the international common chronic renal alograft rejection models, but their application is greatly limited because of difficulty in model preparation and high costs. OBJECTIVE:To explore a new method of establishing SD-Wistar rat models of chronic renal alograft rejection. METHODS: Fifty-six pairs of SD-Wistar rats were subjected to left kidney orthotopic transplantation. The right kidneys of the recipients were intact and used as internal controls. 23 rat recipients were randomly divided into model group (n=15) and control group (n=8). The rats in the model group were injected with cyclosporine microemulsion for 10 days (2 mg/kg/day,i.p.) after kidney transplantation. The rats in the control group were not treated with immunosuppressive therapy. RESULTS AND CONCLUSION:The irreversible acute rejection occurred in al the transplanted kidneys of rats in the control group within 4 weeks, leading to the necrosis of transplanted kidney. Moderate inflammatory cel infiltration appeared in the transplanted kidneys of rats in the model group at 4, 8 and 12 weeks after transplantation. Typical histopathological changes of chronic rejection were observed within 12 weeks after transplantation. The Banff total scores were increased with time after transplantation. Al these histopathological changes were not observed in the intact right kidneys of rat recipients in both groups. The valey value of