| Objective: Aging Sprague-Dawley rats induced by intraperito-neal injection of D-Galactose were intervened by aerobic exercise ahead of aging,duing aging and after aging.To discuss the effect of aerobic exercise intervention on rays of different aging periods,the spatial learning and memory abilities of rats and on expression level of GAP-43 in frontal lobe.Methods: 722-month-old male Sprague-Dawley rats were selected,fed for adaption for 7 days.The six groups were designated as aerobic exercise pretreatment before aging Group(S1),acute senile Group(N1),saline control Group(Na),aerobic exercise intervention in acute aging process Group(S2),aerobic exercise intervention after acute aging Group(S3)and natural feeding after acute aging Group(N2).Each modeled large Group of rats were randomly divided into 2 groups:one group of rats with Morris water maze test 7 days were designated the M Group,namely the S1 M Group,the NDM Group,the NaM Group,the S2 M Group,the S3 M Group and the N2 M Group;the other group of rats with natural feeding 7 days were designated the N Group,namely the S1 N Group,the N1 N Group,the NaN Group,the S2 N Group,the S3 N Group and the N2 D Group.A total of 12 groups(n=6).Intraperitoneal injection of D-Galactose(100mg/kg/d)6 weeks induced brain aging model rats;Morris water maze system evaluated the effects of different periods of aerobic exercise on spatial learning and memory abilities;SOD activity,GSH-Px activity and MDA content in cerebral cortex were determined after the rats were killed in two tranches to evaluate the extent of brain aging rats.GAP-43 expression in frontal lobe of each group of rats were determined using real-time PCR,western blot and immunohistochemical technology.Results:(1)State observation in rats:N1 Group of rats compared with Na Group rats showed poor mental state,such as mental malaise,lethargy,reduced diet,poor skin elasticity and hair removal.(2)Measurements of the free radicals indexes:There was no significant difference in MDA,SOD and GSH-Px between M group and N group(P> 0.05),and the trend was similar.(P <0.05).MDA content of Na Group were very significantly higher than N1 Group(P<0.01),SOD and GSH-Px activities were very significantly lower than that of Na Group(P<0.01);SOD and GSH-Px activities and MDA content of S1 Group had no significant difference with N1 Group(P>0.05);MDA content of S2 Group were very significantly lower than N1Group(P<0.01),SOD and GSH-Px activities were very significantly higher than that of N1 Group(P<0.01);MDA content of S3 Group were very significantly lower than N2 Group(P<0.01),SOD and GSH-Px activities were very significantly higher thanthat of N2 Group(P<0.01).(3)Results of Morris water maze:during the navigation experiment,the average escape latency of the rats in each group decreased gradually with the increase of training times,but the average escape time was different in different groups.The mean escape latency was significantly lower in all groups than in day 1(P<0.01).In addition to the S3 M group,the escape latency of the third day was significantly lower in the other groups of the second day.NaM Group,S2 M Group of rats formed a stable spatial learning and memory after the first 3 days of training,S1 M Group,S3 M Group,N1 M and N2 M Group rats formed a stable spatial learning and memory after the first 4 days of training.During the first day of place navigation test,the escape latency of Na group rats was significantly lower than N1groups(P<0.01);the escape latency of S3 M and N2 group rats was significantly higher than N1 groups(P<0.01,P<0.05).During the sixth day of place navigation test,the escape latency of S1 M Group and N1 m Group of rats had no significant difference(P>0.05);the escape latency of S2 M group rats was significantly lower than N1groups(P <0.01,P<0.05);the escape latency of S3 M group rats was significantly lower than N2 groups(P<0.01,P<0.05).During the seventh day of probe trial,the NaM group through the platform number was significantly more than N1 M group(P<0.05);the through the platform number of S1 M Group and N1 m Group of rats had no significant difference(P>0.05);the S2 M group through the platform number was significantly more than N1 M group(P<0.05);the S3 M group through the platform number was significantly more than N2 M group(P<0.05);(4)Immunohistochemical staining result:Immunoreactivities of GAP-43 in frontal lobe were brown,mainly located in neuronal cytoplasm beside the frontal lobe granulosa cells.The IOD values of the immunological product of GAP-43 in frontal lobe of M Group compared with N Group had no significant difference(P>0.05);The IOD values of the immunological product of GAP-43 in frontal lobe of Na Group very significantly higher than N1Group(P<0.01);The IOD values of the immunological product of GAP-43 in frontal lobe of S1 Group compared with N1 Group had no significant difference(P>0.05);The IOD values of the immunological product of GAP-43 in frontal lobe of S2 Group very significantly higher than N1 Group(P<0.01);The IOD values of the immunological product of GAP-43 in frontal lobe of S3 Group very significantly higher than N2Group(P<0.01).(5)Results of frontal lobe related protein and mRNA test:GAP-43 mRNA and protein expression in frontal lobe of M Group compared with N Group had no significant difference(P>0.05);the expression of GAP-43 m RNA and proteinof Na group were significantly higher than N1 group(P<0.01);the expression of GAP-43 mRNA and protein of S2 group were significantly higher than N1group(P<0.01);the expression of GAP-43 mRNA and protein of S3 group were significantly higher than N2 group(P<0.01).Conclusion:(1)Induced D-galactose could lad to aging characteristics that significantly improve the content of MDA,significantly reduced the activity of SOD and GSH-Px,influence learning and memory ability.These results proved that D-galactose induced brain aging model rats were successful.(2)Doing aerobic exercise in acute aging process or after acute aging showed an effective impact to improve the expression of GAP-43,delay the brain aging,regulate and influence learning and memory ability.(3)It is speculated that GAP-43 expression increase in frontal lobe is one of the mechanisms that aerobic exercise delaying aging rats spatial learning and memory ability decline. |
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