Exercise reverses chronic stress-induced Bax oligomer formation in the cerebral cortex

The effects of fresh Gastrodia elata Blume on the cognitive deficits induced by chronic restraint stress

Chronic restraint stress (CRS) is a classic animal model of stress that can lead to various physiological and psychological dysfunctions, including systemic neuroinflammation and memory deficits. Fresh Gastrodia elata Blume (FG), the unprocessed raw tuber of Gastrodia elata Blume, has been reported to alleviate the symptoms of headache, convulsions, and neurodegenerative diseases, while the protective effects of FG on CRS-induced cognitive deficits remain unclear. This work aimed to evaluate the effects of FG on CRS-induced cognitive deficits through multiplex animal behavior tests and to further explore the related mechanism by observing the expression of mitochondrial apoptosis-related proteins in the mouse hippocampus. In in vivo experiments, mice were subjected to the object location recognition test (OLRT), new object recognition test (NORT), Morris water maze test (MWMT), and passive avoidance test (PAT) to evaluate the learning and memory ability. In in vitro experiments, the expression of the AKT/CREB pathway, the fission- and apoptosis-related proteins (Drp1, Cyt C, and BAX), and the proinflammatory cytokines’ (TNF‐α and IL‐1β) level in the hippocampus was examined. Our results demonstrated that in spontaneous behavior experiments, FG significantly improved the cognitive performance of CRS model mice in OLRT (p < 0.05) and NORT (p < 0.05). In punitive behavior experiments, FG shortened the escape latency in long-term spatial memory test (MWMT, p < 0.01) and prolonged the latency into the dark chamber in non-spatial memory test (PAT, p < 0.01). Biochemical analysis showed that FG treatment significantly suppressed CRS‐induced Cyt C, Drp1, and BAX activation (p < 0.001, p < 0.01 and p < 0.05), promoted the CREB, p-CREB, AKT, and p-AKT level (p < 0.05, p < 0.01 and p < 0.001), and inhibited the CRS‐induced proinflammatory cytokines (TNF‐α and IL‐1β, p < 0.05 and p < 0.001) level in the hippocampus. Taken together, these results suggested that FG could attenuate cognitive deficits induced by CRS on multiple learning and memory behavioral tests.

The effect of moderate exercise on the elevation of Bax/Bcl-2 ratio in oral squamous epithelial cells induced by benzopyrene

Aim:

The aim of this study was to analyze the effect of moderate exercise on the elevation of Bax/Bcl-2 ratio.

Materials and Methods:

Eighteen Mus musculus strain Swiss Webster (Balb/c) were divided into three groups (n=6). K1 and K2 had contact with water 3 times/week for 12 weeks, while the members of the K3 group swam 3 times/week for 12 weeks while carrying load weighed 3% of their body weight. After 5 weeks, they were induced with 0.04 ml oleum olivarum (K1), 0.08 mg benzopyrene/0.04 ml oleum olivarum (K2, K3) 3 times/week for 4 weeks. Immunohistochemistry assays were used to determine the ratio of Bax/Bcl-2 expression. The results were analyzed using an independent t-test.

Result:

The Bax/Bcl-2 ratio increased significantly in K3 compared to K2 (p=0.00).

Conclusion:

Moderate exercise could increase the Bax/Bcl-2 ratio in oral squamous epithelial cells induced by benzopyrene.

Pro-apoptotic Action of Corticosterone in Hippocampal Organotypic Cultures

Elevated levels of glucocorticoids exert neurotoxic effects, and the hippocampus is particularly sensitive to the effects of glucocorticoids. Because some data have indicated that an increased action of glucocorticoids in the perinatal period enhances the susceptibility of brain tissue to adverse substances later in life, the main purpose of the present study was to compare necrotic/apoptotic corticosterone action in hippocampal organotypic cultures obtained from control animals with the effect of this steroid in tissue from prenatally stressed rats. Because the adverse effects of glucocorticoid action on nerve cell viability appear to result mainly from an increase in the intensity of the effects of glutamate and changes in growth factor and pro-inflammatory cytokine synthesis, the involvement of these factors in corticosterone action were also determined. In stress-like concentration (1 μM), corticosterone, when added to hippocampal cultures for 1 and 3 days, alone or jointly with glutamate, did not induce necrosis. In contrast, in 3-day cultures, corticosterone (1 μM) increased caspase-3 activity and the mRNA expression of the pro-apoptotic Bax. Moreover, corticosterone’s effect on caspase-3 activity was stronger in hippocampal cultures from prenatally stressed compared to control rats. Additionally, 24 h of exposure to corticosterone and glutamate, when applied separately and together, increased Bdnf, Ngf, and Tnf-α expression. In contrast, after 72 h, a strong decrease in the expression of both growth factors was observed, while the expression of TNF-α remained high. The present study showed that in stress-like concentrations, corticosterone exerted pro-apoptotic but not necrotic effects in hippocampal organotypic cultures. Prenatal stress increased the pro-apoptotic effects of corticosterone. Increased synthesis of the pro-inflammatory cytokine TNF-α may be connected with the adverse effects of corticosterone on brain cell viability.

Neuroprotection of Early Locomotor Exercise Poststroke: Evidence From Animal Studies

Early locomotor exercise after stroke has attracted a great deal of attention in clinical and animal research in recent years. A series of animal studies showed that early locomotor exercise poststroke could protect against ischemic brain injury and improve functional outcomes through the promotion of angiogenesis, inhibition of acute inflammatory response and neuron apoptosis, and protection of the blood-brain barrier. However, to date, the clinical application of early locomotor exercise poststroke was limited because some clinicians have little confidence in its effectiveness. Here we review the current progress of early locomotor exercise poststroke in animal models. We hope that a comprehensive awareness of the early locomotor exercise poststroke may help to implement early locomotor exercise more appropriately in treatment for ischemic stroke.

Changes in apoptotic factors in hypothalamus and hippocampus after acute and subchronic stress induction during conditioned place preference paradigm

The hypothalamus (HYP) and hippocampus (HIP) are important regions involved in stress responses. These areas are also associated with reward processing. In this study, the effects of acute and subchronic stress on the changes in apoptotic factors (Bax/Bcl-2 ratio, caspase-3 activation and PARP degradation) in the HYP and HIP during conditioned place preference (CPP) paradigm were evaluated. Male Wistar rats were divided into two saline- and morphine-treated supergroups. Each supergroup contained control, acute stress (AS) and subchronic stress (SS) groups. In all groups, CPP paradigm was done and thereinafter alterations of apoptotic factors were measured by western blot. The results revealed that in the HYP, all mentioned factors increased significantly in saline- or morphine-treated animals during AS and SS. On the other hand, in the HIP, Bax/Bcl-2 ratio in saline-treated animals increased significantly during AS and SS, while in morphine-treated animals this ratio did not have any significant alteration during AS and was decreased during SS compared with morphine-control group. Caspase-3 and PARP increased during AS and SS in saline- or morphine-treated animals. For example, caspase-3 increased during AS and SS in morphine-treated animals by 2.4 folds and PARP (89 KDa) increased by 3.1 and 3.5 folds, respectively. Interestingly, the increase of apoptotic factors in morphine-treated animals was more considerable than that of saline-treated animals. These results strongly implied that AS and SS trigger apoptotic events in the HYP and HIP of saline- and/or morphine-treated animals as well as morphine reinforces the effect of stress on the induction of apoptosis.

Early Exercise Protects against Cerebral Ischemic Injury through Inhibiting Neuron Apoptosis in Cortex in Rats

Early exercise is an effective strategy for stroke treatment, but the underlying mechanism remains poorly understood. Apoptosis plays a critical role after stroke. However, it is unclear whether early exercise inhibits apoptosis after stroke. The present study investigated the effect of early exercise on apoptosis induced by ischemia. Adult SD rats were subjected to transient focal cerebral ischemia by middle cerebral artery occlusion model (MCAO) and were randomly divided into early exercise group, non-exercise group and sham group. Early exercise group received forced treadmill training initiated at 24 h after operation. Fourteen days later, the cell apoptosis were detected by TdT-mediated dUTP-biotin nick-end labeling (TUNEL) and Fluoro-Jade-B staining (F-J-B). Caspase-3, cleaved caspase-3 and Bcl-2 were determined by western blotting. Cerebral infarct volume and motor function were evaluated by cresyl violet staining and foot fault test respectively. The results showed that early exercise decreased the number of apoptotic cells (118.74 ± 6.15 vs. 169.65 ± 8.47, p < 0.05, n = 5), inhibited the expression of caspase-3 and cleaved caspase-3 (p < 0.05, n = 5), and increased the expression of Bcl-2 (p < 0.05, n = 5). These data were consistent with reduced infarct volume and improved motor function. These results suggested that early exercise could provide neuroprotection through inhibiting neuron apoptosis.

Exercise as a potential treatment for drug abuse: evidence from preclinical studies

Epidemiological studies reveal that individuals who engage in regular aerobic exercise are less likely to use and abuse illicit drugs. Until recently, very few studies had examined the causal influences that mediate this relationship, and it was not clear whether exercise was effective at reducing substance use and abuse. In the past few years, several preclinical studies have revealed that exercise reduces drug self-administration in laboratory animals. These studies have revealed that exercise produces protective effects in procedures designed to model different transitional phases that occur during the development of, and recover from, a substance use disorder (e.g., acquisition, maintenance, escalation, and relapse/reinstatement of drug use). Moreover, recent studies have revealed several behavioral and neurobiological consequences of exercise that may be responsible for its protective effects in these assays. Collectively, these studies have provided convincing evidence to support the development of exercise-based interventions to reduce compulsive patterns of drug intake in clinical and at-risk populations.

Resistance to the development of stress-induced behavioral despair in the forced swim test associated with elevated hippocampal Bcl-xl expression

Stress may predispose individuals toward depression through down-regulation of neurogenesis and increase in apoptosis in the brain. However, many subjects show high resistance to stress in relation to psychopathology. In the present study, we assessed the possibility that individual-specific patterns of gene expression associated with cell survival and proliferation may be among the molecular factors underlying stress resilience. Brain-derived neurotrophic factor (BDNF), anti-apoptotic B cell lymphoma like X (Bcl-xl) and pro-apoptotic bcl2-associated X protein (Bax) expression were determined in the hippocampus and frontal cortex of rats naturally differed in despair-like behavior in the forced swim test. In the hippocampus, BDNF messenger RNA (mRNA) level was significantly down-regulated 2h after the forced swim test exposure, and at this time point, Bcl-xl mRNA and protein levels were significantly higher in stressed than in untested animals. The ratios of hippocampal Bcl-xl to Bax mRNA negatively correlated with the total time spent immobile in the test. When animals were divided in two groups according to immobility responses in two consecutive swim sessions and designated as stress resilient if their immobility time did not increase in the second session as it did in stress sensitive rats, it was found that resilient rats had significantly higher Bcl-xl/Bax ratios in the hippocampus than stress sensitive animals. The data suggest that naturally occurring variations in the Bcl-xl/Bax ratio in the hippocampus may contribute to individual differences in vulnerability to stress-induced depression-like behaviors.

Chronic unpredictable stress promotes neuronal apoptosis in the cerebral cortex

Stress-mediated loss of synaptogenesis in the hippocampus appears to play a role in depressive and mood disorders. However, little is known about the effect of stress/depression on the plasticity and survival of cortical neurons. In this report, we have examined whether chronic stress increases the vulnerability of neurons in the rat cortex. We have used a chronic unpredictable mild stress (CMS) as a rat model of depression. CMS (5 weeks treatment) produced anedonia and increased corticosterone levels. These effects were accompanied by a detectable increase in caspase-3 positive neurons in the cerebral cortex, suggesting apoptosis. Desipramine (DMI), a well known antidepressant, reversed the pro-apoptotic effect of CMS. These results suggest that antidepressants may reduce the pathological changes seen in stress-induced depressive disorders.