The Effects Of Endogenous Nitric Oxide On The Hippocampal Capillaries Of Rat And The Roles Of Nitric Oxide In The Effects Of Running Exercise On The Capillaries Of Rat Hippocampus

PART ONE THE EFFECTS OF ENDOGENOUS NITRIC OXIDE ONTHE HIPPOCAMPAL CAPILLARIES OF RATObjective: We designed the present experiment to detect the effect of endogenous nitric oxide on the spatial learning and memory ability and the hippocampal capillaries in rat.Methods: After the catheter was successfully inserted into lateral ventricle, in the L-NAME group,L-NAME was injected into lateral ventricle(i.c.v) for 28 days with 5 ul 1 umol/ul each rat once a day,in the L-Arg group L-Arginine was injected into lateral ventricle(i.c.v) for 28 days with 5 ul 0.1 umol/ul and in Sham group, same dose of saline was injected into lateral ventricle. Then, the spatial learning and memory ability of each rat was tested using the Morris water maze test. After the Morris water maze test, the NOS activity and NO content were measured. The total volume of hippocampus, the CA1 region and DG of the hippocampus and the total length, the total volume and the total surface area of the capillaries in CA1 region and DG were determinated using the new stereological techniques.Results: The water maze results showed that the time latencies of Sham group was significantly shorter than the L-NAME group(p <0.05), and there was significant difference of the target zone frequency between L-Arg group and Sham group(p <0.05). The NOS activity and NO content in hippocampus of L-NAME group were both significantly lower than those of Sham group(p < 0.05). The NOS activity and NO content in hippocampus of L-Arg group were both significantly higher than those of Sham group(p < 0.05). The total volumes of the hippocampus, the CA1 region and DG of the hippocampus among the L-NAME group, the L-Arg group and the Sham group were not significantly different(p > 0.05). The total length, the total surface area and the total volume of the capillaries in the CA1 region of the L-NAME group were significantly less than the Sham group(p < 0.05). The total volume of the capillaries in the DG of the L-NAME group was significantly less than the Sham group(p < 0.05).Conclusions: The inhibition of NO generating induced the significant decline in the spatial learning and memory ability of rats and the significant decrease in the total length, the total surface area and the total volume of the capillaries in the CA1 region of rat hippocampus.PART TWO STUDIES ON THE ROLES THAT ENDOGENOUS NITRICOXIDE PLAYS IN THE EFFECTS OF RUNNINGEXERCISE ON THE CAPILLARIES OF RATHIPPOCAMPUSObjective: We designed the present experiment to detect what kinds of role the nitric oxide plays in the effects of running excise on the capillaries of rat hippocampus.Methods: After the catheter was successfully inserted into lateral ventricle, in the L-NAME group and the L-NAME+RE group, L-NAME was injected into lateral ventricle(i.c.v) for 28 days with 5 ul 1 umol/ul each rat once a day,and in the Sham group and RE group, same dose of saline was injected into lateral ventricle. During the period of drug injection, the L-NAME+RE group and the RE group were practicing running excise with the speed of 20 m/min. Then, the spatial learning and memory ability of each rat was tested using the Morris water maze test. After the Morris water maze test, the NOS activity and NO content were measured. The total volumes of hippocampus, the CA1 region and DG of the hippocampus and the total length, the total volume and the total surface area of the capillaries in CA1 region and DG were determined using the new stereological techniques.Results: The water maze results showed that the time latencies of L-NAME group and the L-NAME+RE group rats were significantly longer than the Sham group(p <0.05), and there was significant difference of the target zone frequency between RE group and Sham group(p <0.05). The NOS activity and NO content in hippocampus of RE group were both significantly higher than those of Sham group(p < 0.05). The NOS activity and NO content in hippocampus of L-NAME+RE group were both significantly lower than those of RE group(p < 0.05). The NOS activity and NO content in hippocampus of L-NAME+RE group were both significantly higher than those of L-NAME group(p < 0.05). The total volume of the CA1 region of the hippocampus between the RE group and the Sham group was significantly different(p < 0.05). The total volume of the hippocampus and the CA1 region of the hippocampus between the L-NAME+RE group and the Sham group were significantly different(p < 0.05). The total length of the capillaries in the CA1 region and the DG of the RE group was significantly more than the Sham group(p < 0.05), and also the total surface area of the capillaries in the CA1 region of the RE group was significantly more than the Sham group(p < 0.05). The total length, the total surface area and the total volume of the capillaries in the CA1 region and DG of the L-NAME+RE group were significantly less than the RE group(p < 0.05). The total length, the total surface area and the total volume of the capillaries in the CA1 region and DG of the L-NAME group were significantly less than the Sham group(p < 0.05), and there were no significant differences of the total length, the total surface area and the total volume of the capillaries in the CA1 region and DG of the hippocampus between the L-NAME+RE group and the L-NAME group.Conclusions: 1. Running exercise can increase the content of NO and the activity of NOS in rat hippocampus.2. Running exercise can increase some parameters of the capillaries in the CA1 region and DG of rat hippocampus. 3. During the running excise, endogenous NO plays an important role in regulating angiogenesis in CA1 region and DG of the rat hippocampus.