It has been well documented that exercise promotes neurological rehabilitation in patients with cerebral ischemia. However, the exact mechanisms have not been fully elucidated. This study aimed to discuss the effect of treadmill exercise on expression levels of 5-HT, 5-HT1A receptor (5-HT1AR) and brain derived neurophic factor (BDNF) in rat brains after permanent middle cerebral artery occlusion (pMCAO). A total of 55 rats were randomly divided into 3 groups: pMCAO group, pMCAO and treadmill exercise (pMCAO + Ex) group, and sham-operated group. Rats in pMCAO + Ex group underwent treadmill exercise for 16 days. Neurological function was evaluated by modified Neurological Severity Scores (mNSS). High-performance liquid chromatography-electrochemical detection system was used to determine the content of 5-HT in cortex tissues. The protein levels of 5-HT1AR, BDNF and synaptophysin were measured by Western blot. The mNSS in pMCAO + Ex group was lower than that in pMCAO group on day 19 post-MCAO (p < 0.001). The content of 5-HT dropped to 3.81 ± 1.86 ng/ml in pMCAO group (43.84 ± 2.05 ng/ml in sham-operated group), but increased in pMCAO + Ex group (10.06 ± 1.80 ng/ml). The protein expressions levels of synaptophysin, 5-HT1AR and BDNF were downregulated after cerebral ischemia (p < 0.05), and upregulated after treadmill exercise (p < 0.05). These results indicate that treadmill exercise improves neurologic function, enhances neuronal plasticity and upregulates the levels of 5-HT, 5-HT1AR and BDNF in rats with pMCAO.

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Using panel data on 47 African countries from 1980-2013, this paper investigates the effects of aid on Africa's economic growth from the perspective of political stability. We find that international aid can promote economic growth in Africa, but the effectiveness of aid depends on countries' political stability. Further, the intensity of aid affects its effectiveness. When the aid-GDP ratio is between 0 and 69 per cent, aid can promote economic growth in recipient countries, and when this ratio is 27 per cent, the marginal impact of aid on economic growth is maximized. The findings of this paper suggest that providers of aid should avoid providing a substantial amount of aid to countries at risk of political unrest, and they must determine the optimal scale of aid based on the economic development of recipient countries in order to enable aid to generate better results. Recipient countries should maintain social and political stability and ensure that they do not develop an excessive dependence on aid so that they can achieve the self-sustainable development of their own economies.