Activation of BDNF- and VEGF-mediated Neuroprotection by Treadmill Exercise Training in Experimental Stroke.

Early treatment of ischemic stroke is one of the most effective ways to reduce brains' cell death and promote functional recovery. This study was designed to examine the effect of aerobic exercise on post ischemia/reperfusion injury on concentration and expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) after inducing a neuronal loss in CA1 region of hippocampus in Male Wistar rats. Three experimental groups including sham(S), ischemia/reperfusion-control (IRC) and ischemia/reperfusion exercise (IRE) were used for this purpose. The rats in the IRE group received a bilateral carotid artery occlusion treatment. They ran for 45 minutes on a treadmill five days per week for eight consecutive weeks. Cresyl violet (Nissl), Hematoxylin (H & E) and Eosin staining procedure were used to determine the extent of damage. A ladder rung walking task was used to assess the functional impairments and recovery after the ischemic lesion. ELISA and immunohistochemistry method were employed to measure BDNF and VEGF protein expressions. The result showed that the brain ischemia/reperfusion condition increased the cell death in hippocampal CA1 neurons and impaired motor performance on the ladder rung task whereas the aerobic exercise program significantly decreased the brain cell's death and improved motor skill performance. It was concluded that ischemic brain lesion decreased the BDNF and VEGF expression. It seems that the aerobic exercise following the ischemia/reperfusion potentially promotes neuroprotective mechanisms and neuronal repair and survival mediated partly by BDNF and other pathways.

Cyanocobalamin improves memory impairment via inhibition of necrosis and apoptosis of hippocampal cell death after transient global ischemia/reperfusion.

OBJECTIVES: Brain ischemia/reperfusion (I/R) causes irreversible damage, particularly in the hippocampus. Cyanocobalamin (CNCbl) is known to be crucial for the proper operation of the nervous system. Vitamin B12 has been demonstrated to exert antioxidant effects via direct and indirect mechanisms. It can also protect cortical neurons against glutamate cytotoxicity. This research was conducted to examine CNCbl protection against neuronal cell death in the rat hippocampal region following transient cerebral ischemia. MATERIALS AND METHODS: In this experiment, 48 male Wistar rats were selected, which were randomly divided into four groups (n=12 in each group): sham, ischemia/reperfusion, ischemia/reperfusion + CNCbl 200 and 400 (µg/kg). By occlusion of both common carotids, ischemia induction was performed within 20 min. CNCbl at the doses of 200 and 400 µg/kg was injected (IP) at the start of the reperfusion, 24 and 48 hr following reperfusion. The spatial memory was assessed 7 days following ischemia through the Morris water maze test. Antioxidant enzymes, apoptosis, and necrosis were measured after behavioral tests. RESULTS: CNCbl significantly improved spatial memory impairments (P<0.05), also CNCbl therapy significantly increased both glutathione (P<0.01) and superoxide dismutase (P<0.05) and reduced malondialdehyde (P<0.01) and TNF-α (P<0.05) in comparison with the ischemia group. In addition, CNCbl significantly decreased both apoptosis and necrosis in the hippocampus CA1 (P<0.01). CONCLUSION: CNCbl improves memory impairment following ischemia injury by decreasing neuronal cell death via its antioxidant properties.

Neuroprotective Effects of Exercise on Brain Edema and Neurological Movement Disorders Following the Cerebral Ischemia and Reperfusion in Rats.

INTRODUCTION: Cerebral ischemia and reperfusion causes physiological and biochemical changes in the neuronal cells that will eventually lead to cell damage. Evidence indicates that exercise reduces the ischemia and reperfusion-induced brain damages in animal models of stroke. In the present study, the effect of exercise preconditioning on brain edema and neurological movement disorders following the cerebral ischemia and reperfusion in rats was investigated. METHODS: Twenty-one adult male wistar rats (weighing 260-300 g) were randomly divided into three groups: sham operated, exercise plus ischemia, and ischemia group (7 rats per group). The rats in exercise group were trained to run on a treadmill 5 days a week for 4 weeks. Transient focal cerebral ischemia and reperfusion were induced by middle cerebral artery occlusion (MCAO) for 60 minutes, followed by reperfusion for 23 hours. After 24 hours ischemia, movement disorders were tested by a special neurological examination. Also, cerebral edema was assessed by determining the brain water content. RESULTS: The results showed that pre-ischemic exercise significantly reduced brain edema (P<0.05). In addition, exercise preconditioning decreased the neurological movement disorders caused by brain ischemia and reperfusion (P<0.05). CONCLUSION: Preconditioning by exercise had neuroprotective effects against brain ischemia and reperfusion-induced edema and movement disorders. Thus, it could be considered as a useful strategy for prevention of ischemic injuries, especially in people at risk.

Protection of Hippocampal CA1 Neurons Against Ischemia/Reperfusion Injury by Exercise Preconditioning via Modulation of Bax/Bcl-2 Ratio and Prevention of Caspase-3 Activation.

INTRODUCTION: Ischemia leads to loss of neurons by apoptosis in specific brain regions, especially in the hippocampus. The purpose of this study was investigating the effects of exercise preconditioning on expression of Bax, Bcl-2, and caspase-3 proteins in hippocampal CA1 neurons after induction of cerebral ischemia. METHODS: Male rats weighing 260-300 g were randomly allocated into three groups (sham, exercise, and ischemia). The rats in exercise group were trained to run on a treadmill 5 days a week for 4 weeks. Ischemia was induced by the occlusion of both common carotid arteries (CCAs) for 20 min. Levels of expression of Bax, Bcl-2, and caspase-3 proteins in CA1 area of hippocampus were determined by immunohistochemical staining . RESULTS: The number of active caspase-3-positive neurons in CA1 area were significantly increased in ischemia group, compared to sham-operated group (P<0.001), and exercise preconditioning significantly reduced the ischemia/reperfusion-induced caspase-3 activation, compared to the ischemia group (P<0.05). Also, results indicated a significant increase in Bax/Bcl-2 ratio in ischemia group, compared to sham-operated group (P<0.001). DISCUSSION: This study indicated that exercise has a neuroprotective effects against cerebral ischemia when used as preconditioning stimuli.

Exercise preconditioning exhibits neuroprotective effects on hippocampal CA1 neuronal damage after cerebral ischemia.

Recent evidence has suggested the neuroprotective effects of physical exercise on cerebral ischemic injury. However, the role of physical exercise in cerebral ischemia-induced hippocampal damage remains controversial. The aim of the present study was to evaluate the effects of pre-ischemia treadmill training on hippocampal CA1 neuronal damage after cerebral ischemia. Male adult rats were randomly divided into control, ischemia and exercise + ischemia groups. In the exercise + ischemia group, rats were subjected to running on a treadmill in a designated time schedule (5 days per week for 4 weeks). Then rats underwent cerebral ischemia induction through occlusion of common carotids followed by reperfusion. At 4 days after cerebral ischemia, rat learning and memory abilities were evaluated using passive avoidance memory test and rat hippocampal neuronal damage was detected using Nissl and TUNEL staining. Pre-ischemic exercise significantly reduced the number of TUNEL-positive cells and necrotic cell death in the hippocampal CA1 region as compared to the ischemia group. Moreover, pre-ischemic exercise significantly prevented ischemia-induced memory dysfunction. Pre-ischemic exercise mighct prevent memory deficits after cerebral ischemia through rescuing hippocampal CA1 neurons from ischemia-induced degeneration.

Pre-ischemic exercise reduces apoptosis in hippocampal CA3 cells after cerebral ischemia by modulation of the Bax/Bcl-2 proteins ratio and prevention of caspase-3 activation.

Ischemia induces physiological alterations in neurons that lead to cell death. This study investigated the effects of pre-ischemic exercise on CA3 neurons. Rats were divided into three groups. Animals in the exercise group were trained 5 days a week for 4 weeks. Ischemia was induced by occlusion of both common carotid arteries (CCAs) for 20 min. Apoptotic cell death was detected by TUNEL assay. Furthermore, expression of different proteins was determined by immunohistochemical staining. The number of TUNEL-positive cells was significantly increased in the ischemia group, but pre-ischemic exercise significantly reduced apoptotic cell death (P < 0.001). In addition, our results showed a significant increase in the Bax/Bcl-2 ratio in the ischemia group. Pre-ischemic exercise attenuated this ratio (P < 0.05). Furthermore, the number of active caspase-3-positive neurons was significantly increased in the ischemia group, which was reduced markedly by exercise preconditioning (P < 0.05). This study showed that pre-ischemic exercise can exert neuroprotective effects against ischemia in CA3 neurons.

Visfatin reduces hippocampal CA1 cells death and improves learning and memory deficits after transient global ischemia/reperfusion.

Visfatin is a novel adipocytokine with insulin-mimetic effect which plays a role in glucose-lowering effect of insulin and improves insulin sensitivity. It has been linked to a variety of cellular processes and its plays important roles in cell apoptosis and survival. Moreover, cerebral ischemia causes loss of hippocampus pyramidal cells, therefore, in this study; we investigated the neuroprotective effect of visfatin after global cerebral ischemia in male rats. Both common carotid arteries were occluded for 20 minutes followed by 4 days of reperfusion. Animals were treated with either the Visfatin (intracerebro-ventricular; 100 ng) or saline vehicle (2 µl) at the time of reperfusion. Behavioral examination, apoptosis and necrosis assessment were performed 4 days after ischemia. Visfatin significantly reduced Caspase-3 activation (P < 0.001), TUNEL positive cells (P < 0.05) and necrotic cell death in the CA1 region of the hippocampus (P < 0.001). Moreover, treatment with visfatin significantly improved memory deficits of cerebral ischemia-reperfusion rats (P < 0.05). The results suggest that visfatin via its antiapoptotic properties has significant neuroprotective effects on cerebral ischemia reperfusion injury in rats.

Nampt/PBEF/visfatin exerts neuroprotective effects against ischemia/reperfusion injury via modulation of Bax/Bcl-2 ratio and prevention of caspase-3 activation.

Nicotinamide phosphoribosyl transferase/pre-B cell colony-enhancing factor/visfatin (Nampt/PBEF/visfatin) is an adipocytokine. By synthesizing nicotinamide adenine dinucleotide (NAD(+)), Nampt/PBEF/visfatin functions to maintain an energy supply that has critical roles in cell survival. Cerebral ischemia leads to energy depletion and eventually neuronal death by apoptosis in specific brain regions specially the hippocampus. However, the role of Nampt/PBEF/visfatin in brain and cerebral ischemia remains to be investigated. This study investigated the role of administration Nampt/PBEF/visfatin in hippocampal CA3 area using a transient global cerebral ischemia model. Both common carotid arteries were occluded for 20 min followed by reperfusion. Saline as a vehicle and Nampt/PBEF/visfatin at a dose of 100 ng were injected intracerebroventricularly (ICV) at the time of cerebral reperfusion. To investigate the underlying mechanisms of Nampt/PBEF/visfatin neuroprotection, levels of expression of apoptosis-related proteins (caspase-3 activation, Bax protein levels, and Bcl-2 protein levels) 96 h after ischemia were determined by immunohistochemical staining. The number of active caspase-3-positive neurons in CA3 was significantly increased in the ischemia group, compared with the sham group (P < 0.001), and treatment with Nampt/PBEF/visfatin significantly reduced the ischemia/reperfusion-induced caspase-3 activation, compared to the ischemia group (P < 0.05). Also, results indicated a significant increase in Bax/Bcl-2 ratio in the ischemia group, compared with the sham group (P < 0.01). However, treatment with Nampt/PBEF/visfatin significantly attenuated the ischemia/reperfusion-induced increase in Bax/Bcl-2 ratio, compared with the ischemia group (P < 0.05). This study has indicated that Nampt/PBEF/visfatin entails neuroprotective effects against ischemia injury when used at the time of cerebral reperfusion. These neuroprotective mechanisms of Nampt/PBEF/visfatin occur through decrease the expression ofproapoptotic proteins (cleaved caspase-3 and Bax) and, on the other hand, increase the expression ofantiapoptotic proteins (Bcl-2). Thus, our findings indicate that Nampt/PBEF/visfatin is a new therapeutic target for cerebral ischemia.