Effect Of Appropriate Physical Exercise On Neurogenesis Of SVZ-associated Region In D-galactose-induced Aging Mice

Objective: By observing the neurogenesis of young Kunming mice after appropriate physical exercise, which injected D-galactose, this experiment is aimed to observe neck subcutaneous injection of D-galactose can lead to rapid aging modle of Kunming mice, whose neurogenesis have been damaged, and appropriate physical exercise can improve the damage on D-galactose-induced aging mice significantly. At the same time, to prove that the appropriate physical exercise can improve neurogenesis on normal mice, and compare the function with D-galactose-induced aging mice.Methods: 40 healthy Kunming mice weight from 20 g to 25 g, were randomly divided into four groups,10 mice of every group:control group(Con group),control+physical exersize group(Con+Phy group), modle group(Mod group)and modtrol+physical exersize group(Mod+Phy group). Mod group and Mod+Phy group daily neck subcutaneous injection of D-galactose(125 mg/kg),At the same time, Con+Phy group and Mod+Phy group for 30 minutes daily appropriate physical exercise training for 5 days every week, for 8 weeks.1 Morris water maze(MWM)test: After injection and physical exersise, the SAMmice were raised 1 days under the environment of labyrinth laboratory first. Training was started with the fixed position location underway trials, which can value the learning ability of the mice, The MWM was divided equally for 4 quadrants; the plat was put among them in one quadrant. The mouse went into water from neighbor quadrant midpoint and peripheral point of offside quadrant, towards the wall in pond, and the videofrequency acquisition system tracken and recorded escape latency. After 5 days removed the plat and undertaken exploring trial, which value the memory of the mice,and taken notes the times that the mouse acrossing span flat roof in 60 s.2 Preparate tissue slices and observe. 10 mice of every group were taken out, broken right auricle and perfused quickly with normal saline and subsequently fixed with 4% parafom via left ventricle. The SVZ-assiociated region(including SVZ, rostral migratory stream and part of lateral ventricle) was taken to make 4 sets of paraffin sections using for HE staining, and Sox-2, Ki-67 and DCX immunohistochemical staining.Results:1 In the MWM test, there was significantly difference among four groups in the fixed position location underway trials(P<0.05):the escape latency of Mod group was longer than Con group(P<0.05), Mod+Phy group was shorter than Mod group(P<0.05), even shorter than Con group(P<0.05). The escape latency of Con+Phy group was shorter than Con group(P<0.05),but the decline level was lower than the former. In the exploring trial, the times of acrossing span flat roof were significantly difference among four groups(P<0.05). The times of Mod+Phy group was more than Mod group(P<0.05), Con+Phy group was more than Con group(P<0.05), whose increase level was lower than the former. Mod group was less than Con group, but there was no significantly difference between them(P>0.05); 2 With HE staining, neurons in contex of Con group and Con+Phy group have clear layers stained evenly and with regular cell shape. While neurons in Mod group and Mod+Phy group were decreased cellular layers with cell nucleuses karyochrome and pyknosis. Neck subcutaneous injection of D-galactose can lead to the pathological lesion obviously. The ratio of modified cell and total cells was higher in the Mod group and Mod+Phy group,comparing with Con group(P<0.05). The ratio of Mod+Phy group was lower than Mod group(P<0.05). The ratio of Con+Phy group was lower than Con group(P<0.05). whose decrease level was lower than the former; 3 With Ki-67, Sox-2 and DCX immunohistochemistry, count the immune positive cells in SVZ-assiociated region of four groups. the number of Sox-2, Ki-67 and DCX immune positive cells in Mod group was less than that in the Con group(P<0.05). The numbers of Sox-2, Ki-67 and DCX immune positive cells in Mod+Phy group was more than that the Mod group(P<0.05), that the Ki-67 and Sox-2 immune positive cells number was even more than in the Con group(P<0.05). The number of Sox-2, Ki-67 and DCX immune positive cells in Con+Phy group was more than in the Con group(P<0.05), whose increase level was lower than the former.Conclusions:1 Neck subcutaneous injection of D-galactose can lead to neuron damage,decline the learning ability and memory of mice, and causes the decrease of new born neurons in the SVZ-associated region.2 Appropriate physical exercise training can improve the damage of learning ability and memory derived from neck subcutaneous injection of D-galactose, and promote the neurogenesis in the SVZ-associated region. Make the associated index similar to the normal level.3 Appropriate physical exercise training can promote the neurogenesis of normal mice, but the effect is less remarkable than on rapid aging D-galaetose mice.