Effects Of Aerobic Exercise On Synaptic Plasticity And PKA Expression In Hippocampus Of Aging Rats

Abstract

PURPOSE: To investigate the Effects of aerobic exercise on synaptic plasticity and PKA expression in hippocampus of aging rats. METHODS: Sixty male SD rats were divided into 3 group at random: saline control group(SC), aging model group(S), aerobic exercise intervention on aging group(SE). Aging model was established by injecting low galactose via peritoneal, 100 mg / kg, once a day for 6 weeks in S and SE. And S were injected the same dosage of saline. D-gal were injected in S and SE and were simultaneously administered for a 6-week swimming exercise intervention, 6 days a week for 1 hour a day. And the general state of rats was observed weekly. At the end of modeling and swimming, Morris water maze was used to evaluate the spatial learning and memory ability. HE staining was used to observe Morphological changes of Hippocampus. The expression of PKA was tested by western blotting. The expression of BDNF and SYN in Hippocampus was tested by immunofluorescence. The experimental data was reported as mean ± SE. level of significance was set at α = 0.05. RESULTS: 1) Compared with SC and SE, S showed obvious signs of aging, such as loss of weight, decrease of activity, loss hair and neurons significantly reducing, the cell morphology was incomplete and the chromatin was unevenly colored. 2) The Morris water maze test was showed that: Compared with SC, the escape latency of S was significantly increased (P < 0.01); the number of crossing the platform was significantly reduced (P < 0.01). Compared with S, the escape latency of SE was significantly decreased (P < 0.05), and the number of crossing the platform was significantly increased (P < 0.01). 3) Compared with S, the expression of PKA was significantly increased in SC and SE (1.30 ± 0.03 vs. 0.77 ± 0.07, P < 0.01; 1.22 ± 0.11 vs. 0.77 ± 0.07, P < 0.05). 4) Compared to S, the immunofluorescence density values of BDNF and SYN significantly increasing was observed in SC and SE (25.52 ± 1.34 vs. 16.83 ± 1.30, P < 0.01; 23.15 ± 1.26 vs. 16.83 ± 1.30, P < 0.05); (53.85 ± 6.14 vs. 25.68 ± 1.36, P < 0.01; 51.18 ± 1.26 vs. 25.68 ± 1.36, P < 0.01). CONCLUSIONS: 6 weeks of aerobic exercise effectively reverses brain injury and learning and memory impairment in aging rats. The mechanism may be related to significantly up-regulate the expression of PKA in hippocampus to promote synaptic plasticity and improve learning and memory ability.