| Human brain frontal cortex controls senior intelligence activity,such as language,emotions and thoughts is the main functional areas,brain damage from stress or other injuries easily leads to a change in its function,and disorders of mental activities and defects,namely,mental disorder after traumatic brain injury.One of the salient features of mental disorder is behavioral change,which is characterized by lack of attention,slow response and clumsiness.Studies have shown that mental disorders are a chronic form of astrocyte pathological changes,including reduced numbers and dysfunction.Astrocytes can synthesize large amounts of nerve growth factor(NGF).There is increasing evidence that NGF activates the Trk A pathway involved in neurorestoration by binding and activating its receptor tyrosine kinase receptor A(Trk A).The study showed that the expression of glutamate decarboxylase 67(GAD67)was decreased in mental disorders.In this study,we established a model for the mental disorder of frontal lobe injury in rats,and transplanted type 2 astrocytes(T2As)into the brain of mental disorders to observe the effect of T2 As on the behavior of rats.And the expression of NGF receptor Trk A,p75 neurotrophic factor receptor(p75NTR)and mitogen-activated protein kinase(MAPK)signalling related proteins p-Erk1/2 and GAD67 were detected.Objective: T2 As was implanted into the brain of rats with mental disorder to investigate the neurorestorative effect of T2 As in rats with mental disorder and explore its possible molecular mechanisms.Methods:(1)Using the constant temperature oscillating method and the differential adhesion method to separate the purified oligodendrocyte precursor cells(OPCs),the OPCs induced differentiation into T2 As in the 10% fetal calf serum(FCS)culture medium.T2 As was identified by immunofluorescence chemistry and 5-bromo-2-deoxyuridine(Brd U)was used to label the T2 As.(2)60 SD rats were randomly divided into sham group,frontal lobe injury group and T2 As transplantation group.A mental disorder model was established by using stereotaxic and blade cutting to damage the frontal cortex of rats.Stereotactic technique was used to transplant T2 As to the lateral ventricle of the rats with mental disorder(on the same side of injury).The influence of T2 As on the behavior of rats was analyzed by using sugar preference test and open field test.(3)Western blot was applied to detect the expression of Trk A,p75 NTR,p-Erk1/2 and GAD67 in the frontal cortex,striatum and hippocampus at 4 weeks,6 weeks and 8 weeks.Results:(1)Immunofluorescence chemical results show that T2 As can be successfully cultured with constant temperature oscillation and differential adhesion method and incubation with 10 μmol/L Brd U for 24 h achieved 56±3.2% of the labeling rate.(2)Behavioral results showed that the sugar preference began to decline significantly in 4 weeks after the frontal lobe injury(P<0.05),that is,the pleasure experience decreased.In the open field test,the number of crossed squares and rearing were significantly reduced in 6 weeks(P<0.05),indicating that the activity level and the exploration ability decreased after the frontal lobe injury.Sugar water preference,the number of crossed squares and rearing of T2 As transplanted rats were significantly higher than the frontal lobe injury rats(P<0.05).(3)The Brd U markered cells were observed in the frontal cortex after 4 weeks of T2 As transplantated at the lateral ventricle.(4)Western blot results showed significant changes in the expression of Trk A,p75 NTR,p-Erk1/2 and GAD67 in the prefrontal cortex,striatum and hippocampus after the frontal lobe injury and transplantation of T2 As.The expression of Trk A,p75 NTR and p-Erk1/2 in the frontal cortex was significantly lower than that in the sham operation group at 6 weeks and 8 weeks,and the expression levels of these molecules were significantly increased after the transplantation of T2As(P<0.05).The expression of Trk A and p-Erk1/2 in the striatum was the same as that in the frontal cortex,and the expression of p75 NTR did not change significantly.In the hippocampus,the expression of Trk A and p75 NTR in rats did not change significantly in 6 weeks and 8 weeks,while the expression of p-Erk1/2 in the frontal lobe injury group was significantly lower than that in the sham group,and the T2 As transplantation group was significantly higher than the frontal lobe injury group(P<0.01).(5)The expression of GAD67 has no significant change in the frontal cortex and striatum after 4 weeks of the frontal lobe injury and transplantation T2 As and the expression of GAD67 in the injured group was significantly lower than that in the sham group at 6 weeks and 8 weeks,while the T2 As transplantation group was significantly higher than the injury group(P<0.05).In the hippocampus,the expression of GAD67 in 4 weeks was no difference in the lesion group and the sham group,but the transplantation group was significantly higher than the injury group(P<0.05).The expression in the frontal cortex and striatum showed the same trend in 6 weeks and 8 weeks.Conclusions: T2 As can be successfully cultured by constant temperature oscillation and differential adhesion method.Behavioral results showed that,in rats with frontal lobe injury induced anhedonia and decreased activity ability,the implantation of T2 As could significantly improve the behavioral symptoms of mental disorders.The decrease of Trk A p75 NTR,p-Erk1/2 expression is the possible molecular mechanism for the change of rat behavior after frontal lobe injury.Transplanting T2 As can increase the expression of Trk A,p75 NTR,p-Erk1/2 and GAD67,suggesting that T2 As may be the activation of NGF/Trk A pathway to repair GABA neurons to improve the symptoms of mental disorders in rats. |
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