Studies On The Effects Of Running Exercise On The Cortical Capillaries And Mechanism Of The Rats

PART ONE THE EFFECTS OF RUNNING EXERCISE ON THE SPATIAL LEARNING AND MEMORY ABILITY AND THE CORTICAL CAPILLARIES IN AGED RATSObjective:The aim of the current study was to determine the effects of long-term running exercise on spatial learning, memory ability and cortical capillaries in old-aged rats.Methods:Fourteen-month-old female and male Sprague-Dawley rats were randomly divided into an exercised group (EG) and a non-exercised group (NG).The EG rats were trained to run on the treadmill for 14 months, and the NG rats were housed under identical conditions without running. The spatial learning and memory ability was assessed with the Morris water maze, and the parameters of the cortical capillaries were quantitatively investigated with an immunohistochemistry technique and the stereological methods.Results:In 28-month-old male rats, the escaped latencies of Morris water maze of EG were significantly different from those of NG (p<0.05). However, in 28-month-old female rats, the escaped latencies of Morris water maze of EG were not significantly different from those of NG (p >0.05). In 28-month-old male and female rats, the total cortex volume was not significantly different between the EG and NG (p>0.05). In 28-month-old male rats, the total length, total volume and the total surface area of the cortical capillaries in EG were significantly increased when compared the NG (p<0.05). In 28-month-old female rats, the total volume and the total surface area of the cortical capillaries in EG were significantly increased when compared the NG (p<0.05). However, in 28-month-old female rats, the total length of the cortical capillaries was not significantly different between EG and NG (p>0.05).Conclusions:1. These data demonstrated that long-term exercise had positive effects on spatial learning and memory ability in male rats.2. Long-term exercise had positive effects on cortical capillaries in both male and female old-aged rats.PART TWO STUDIES ON THE ROLES THAT ENDOGENOUS NITRIC OXIDE PLAYS IN THE EFFECTS OF RUNNING EXERCISE ON THE SPATIAL LEARNING AND MEMORY ABILITY OF RATS AND ON THE CORTICAL CAPILLARIES OF RATSObjective:To investigate the roles that endogenous nitric oxide plays in the effects of running exercise on the spatial learning and memory ability and on the cortical capillaries of rats.Methods:One hundred and twenty-five eight-week-old male Sprague Dawley rats were divided into five groups after the lateral ventricle catheter surgery was finished. The five groups include Sham group (intracerebroventricular (i.c.v) normal saline 5μl/day), Exercise+ L-NAME group (running exercise and i.c.v L-NAME 5μmol/day), Exercise group (running exercise and i.c.v normal saline 5μl/day), L-NAME group (i.c.v L-NAME 5μmol/day), L-Arg group (i.c.v L-Arg 0.5 μmol/day), the treatment lasted four weeks, with once treatment daily and seven consecutive days per week. Parameters of the running exercise were 20 m/min, seven days/week, four weeks. After the end of the exercise and i.c.v intervention, the spatial learning and memory ability of each group rats were tested using the Morris water maze. After the Morris water maze test, the NOS activity in cerebral cortex of each group rats was measured using the method of nitric acid reductase and metabolic chemistral method, and the parameters of the cortical capillaries were quantitatively investigated with an immunohistochemistry technique and the stereological methods.Results:1. In the first day of the visible platform test, the escaped latency of Morris water maze was not significantly different among the five groups (p>0.05). The results of the time latency in spatial navigation trails from 2nd day to 6th day were as followings. The escaped latencies of Exercise+L-NAME group, L-Arg group and L-NAME group were significantly longer than Sham group (p<0.05). The escaped latencies of Exercise group was significantly shorter than Exercise+L-NAME group (p <0.05). There were no significant differences in the escaped latencies among other groups (p>0.05). The target zone frequency in Exercise group was significantly higher than Sham and Exercise+L-NAME group (p <0.05). There were no significant differences in the target zone frequency among other groups (p>0.05).2. The NOS activity of cerebral cortex in Exercise group and L-Arg group was significantly higher than L-NAME group (p<0.05). There were no significant differences in the NOS activity of the cortex among other groups (p>0.05).3. Stereological results of the cortical capillaries:①The total length of the cortical capillaries in Exercise+L-NAME group and L-NAME group were significantly decreased compared with Sham group (p<0.01).The total length of the cortical capillaries in Exercise group and L-Arg group were significantly increased compared with Sham group (p<0.01). The total length of the cortical capillaries in Exercise group and L-Arg groups were significantly increased compared with L-NAME group and Exercise+L-NAME group (p <0.01).②The total volume of the cortical capillaries in Exercise group and L-Arg group were significantly increased compared with Sham group, Exercise+L-NAME group and L-NAME group (p<0.01), and there were no significant differences in the total volume of the cortical capillaries among other groups (p>0.05). ③The total surface area of the cortical capillaries in Exercise group and L-Arg group were significantly increased compared with Sham group, Exercise+L-NAME group and L-NAME group (p<0.01), and there were no significant differences in the total surface area of the cortical capillaries among other groups (p>0.05).Conclusions:1. Running exercise improved the NOS activity in cerebral cortex.2. The endogenous nitric oxide signaling pathway regulated the spatial learning and memory ability in running exercise rats.3. The endogenous nitric oxide signaling pathway regulated the cortical capillaries in running exercise rats.PART THREE THE MECHANISM OF ENDOGENOUS NITRIC OXIDE REGULATING THE ANGIOGENESIS IN THE CEREBRAL CORTEX OF RUNNING EXERCISE RATSObject:To investigate the mechanisms of the endogenous nitric oxide regulating the angiogenesis in the cerebral cortex of running exercise rats.Methods:The expressions of angiogenesis factors VEGF, FGF-2 and angiogenesis inhibitor endostatin, angiostatin mRNA and protein in cerebral cortex were tested using real time-PCR and Western blot.Results:mRNA:①VEGF mRNA expression in Exercise group was significantly increased compared with Sham group, Exercise+L-NAME group and L-NAME group (p<0.01). VEGF mRNA expression in L-NAME group was significantly decreased compared with Sham group (p <0.05). VEGF mRNA expression in L-Arg group was significantly increased compared with L-NAME group (p<0.05). There were no significant differences in VEGF mRNA expression among Sham group, Exercise+L-NAME group and L-NAME group (p>0.05). ②FGF-2 mRNA expression in Exercise group was significantly increased compared with Sham group, Exercise+L-NAME group and L-NAME group (p<0.05). There were no significant differences in FGF-2 mRNA expression among Sham group, Exercise+L-NAME group and L-NAME L-Arg group (p >0.05). ③There were no significant differences in Angiostatin mRNA expression among the five groups.④Endostatin mRNA expression in Exercise group was significantly decreased compared with Sham group, Exercise+L-NAME group and L-NAME group (p<0.01). Endostatin mRNA expression in L-Arg group was significantly decreased compared with L-NAME group (p<0.05), and there were no significant differences in Endostatin mRNA expression among Sham group, Exercise+L-NAME group and L-Arg group (p>0.05). Protein:①VEGF expression in Exercise group, L-Arg group and L-NAME group were significantly increased compared with Sham group (p<0.01). VEGF expression in Exercise group and L-Arg group were significantly increased compared with Exercise+L-NAME group (p<0.05), and there were no significant differences in VEGF expression among other groups (p>0.05). ②FGF-2 expression in Exercise group, L-Arg group and L-NAME group were significantly increased compared with Sham group and Exercise+L-NAME group (p<0.01). FGF-2 expression in L-Arg group was significantly increased compared with L-NAME group (p<0.05), FGF-2 expression in Sham and Exercise+L-NAME group were significantly decreased compared with L-NAME group (p<0.01), and there were no significant differences in FGF-2 expression among other groups (p>0.05).③There were no significantly different in Angiostatin expression among the five groups (p>0.05).④Endostatin expression in Exercise group and Exercise+L-NAME group were significantly decreased compared with Sham group (p<0.01). Endostatin expression in L-Arg group was significantly decreased compared with Sham group (p<0.05). Endostatin expression in Exercise group was significantly decreased compared with L-NAME group (p<0.01), and there were no significant differences in Endostatin expression among other groups (p>0.05).Conclusions:1. Endogenous nitric oxide could regulate angiogenesis factors VEGF, FGF-2 directly.2. Running exercise could regulate angiogenesis factors VEGF, FGF-2 and angiogenesis inhibitor Endostatin through the endogenous nitric oxide signaling pathway.3. Under the exercise conditions, endogenous nitric oxide had a stronger regulatory role for angiogenesis factors and angiogenesis inhibitor.