We hypothesized that exercise before and/or after ischemia can improve hippocampus inflammation, cell apoptosis, and motor function in rats. For this purpose, we analyzed the expression of NF-κB, TNF-α, caspas3 in the CA1, and the ladder rung walking test to assess sensorimotor function. The present findings revealed that treadmill exercise pre and/or post ischemia, has significant effect on inflammation response, neural cell death and motor function recovery. Therefore, exercise before and after ischemic stroke leads to decrease in inflammatory proteins and reduces cell apoptosis. The most remarkable finding of the present study is that eight-week pre and eight-week post-exercise in combination provides better results compared to each protocols alone.
The molecular underpinnings of inflammatory damage following cerebral ischemia have been well established. Secondary brain injury is shown to be caused predominantly by brain inflammation during reperfusion through intensifying both the accumulation of inflammatory cytokines and microvascular dysfunction throughout involved areas of the brain tissue . Ischemia results in a change in transcriptional activity of many inflammatory components through NF-κB that increases the expression of a large number of genes, including those associated with inflammatory responses ,,. The TNF-α factor is a particularly important component in the inflammatory cascades that play a pivotal role in neurodegeneration and generally associated with initiation of apoptosis ,. This is a major inflammatory cytokine, molecular activities of which deeply affects brain response to stroke. TNF-α has toxic and trophic effects on neuronal tissues which is concentration-dependent. It is suggested that chronic increase of TNF-α in low levels, observed in preconditioning exercises, may improve tolerance to this cytokine  . This gradual increase in TNF-α expression, triggered by preconditioning exercise, is correlated with brain damage following ischemia in rats . In addition, TNF-α receptors are shown to be down-regulated through preconditioning exercise . As a result, chronic stimulation by low levels of TNF-α may cause desensitization of TNF-α receptors.
Consistent with these studies are findings that shows exercise down-regulates the overexpression of NF-κB following cerebral ischemia in rats  and therefore inhibits TNF-α. For example, rehabilitation achieved through exercise promotes neuroprotection against cerebral ischemia–reperfusion injury via down-regulation of the expression of pro-inflammatory mediators . In hippocampus the inflammatory cytokines were found down-regulated on day 14 but again interestingly elevated on day 21, which may be linked to repair mechanisms following ischemia . Cytokines including TNF-α was found to be at their maximum level on day 7, 14 and remained elevated till day 21 following ischemia . While opposite changes in the BDNF levels were observed as BDNF expression was elevated on day 14 and down-regulated on day 21, the down-regulation of BDNF plays a major role in the development of inflammation . It is reported that expression and trophic levels in the blood and brain after a variety of physical activities in human and animal subjects is increased . Trophic factors are found in large quantities in the hippocampus. So, increased levels of BDNF might have led to a decreased in the levels of inflammatory cytokines in the hippocampal region of the rat brain .
Based on the results of the present study, it appears that pre and/or post-stroke exercise may adjust the inflammatory injury associated with ischemia by decreasing levels of TNF-α and NF-kB that may reduce apoptosis. The results of our study confirms that intervention containing eight-week exercise before and after ischemic stroke can dramatically decrease inflammatory proteins and cell apoptosis in subjects compared to preconditioning and recovery exercise alone. This non-pharmaceutical and non-invasive strategy, thus, may be the most helpful way to prevent possible consequences of ischemia and has the potential to provide better recovery following ischemic conditions.
This is suggested that increase in NF-kB and TNF-α levels causes endothelial up-regulation and facilitates adhesion of leukocytes to the microvascular endothelium, congestion of the microcirculation, and infiltration of leukocytes into the parenchyma, all of which are likely to exacerbate ischemic injury . During the process of neuroinflammation, apoptosis-regulatory proteins are repeatedly implicated in the susceptibility of neuron. Markers of apoptotic cell death include caspase-3, a terminal protein in the apoptotic cascade inducing irreversible fragmentation of DNA . In the present study, exercise suppressed brain inflammation-induced TUNEL-positive cells and caspase-3 expression in the cortex. From these results, it can be suggested that exercise has ameliorating effect on brain inflammation-induced apoptotic neuronal cell death in CA1.
In this regard, there is no difference between exercise pre and post-ischemia, although combination of these exercise programs has significant effects.
Apoptosis appears to play an important role in neuronal cell death induced by brain inflammation . TNF induces phosphorylation on apoptotic genes such as caspase-3, triggering cellular deterioration . TNF-induced increase of TUNEL staining and caspase-3 expression caused degenerative change in the hippocampus . Exercise training may improve cerebral blood flow by enhancement of endothelium-dependent laminar shear stress, diminishing cerebral microvascular endothelial cell apoptosis in mice, which may be one of the possible protective mechanisms of exercise training (within 24 h post-stroke) .
The results regarding motor functional recovery tests (horizontal ladder) showed that 2 h after the stroke there was no significant difference between ischemic groups but the difference was significant after 24 h and 8 weeks. Eight-week exercise, either as preconditioning or as recovery, demonstrated optimal results. However, combination of exercise before and after ischemic stroke provides effects that are more significant. One of the potential mechanisms may be the duration of exercise program that was sixteen weeks compared to eight weeks for other groups. In the present study, we used progressive and a more vigorous level of exercise training (longer duration, increased speed, and greater incline).