Low-intensity physical training recovers object recognition memory impairment in rats after early-life induced Status epilepticus

Forced Physical Training Increases Neuronal Proliferation and Maturation with Their Integration into Normal Circuits in Pilocarpine Induced Status Epilepticus Mice

Increased number of newly-born neurons produced at latent stage after status epilepticus (SE) contribute to aberrant rewiring of hippocampus and are hypothesized to promote epileptogenesis. Although physical training (PT) was reported to cause further increase in neurogenesis after SE, how PT affect their integration pattern is still elusive, whether they integrate into normal circuits or increase aberrant integrations is yet to be determined. To understand this basic mechanism by which PT effects SE and to elaborate the possible role of neuronal integrations in prognosis of SE, we evaluated the effect of 4 weeks of treadmill PT in adult male mice after pilocarpine-induced SE on behavioral and aberrant integrations' parameters. Changes in BDNF gene methylation and its protein level in hippocampus was also measured at latent stage (2-weeks) to explore underlying pathways involved in increasing neurogenesis. Our results demonstrated that although PT increased proliferation and maturation of neurons in dentate gyrus, they showed reduced aberrant integrations into hippocampal circuitry assessed through a decrease in the number of ectopic granular cells, hilar basal dendrites and mossy fiber sprouting as compared to non-exercised SE mice. While SE decreased the percentage methylation of specific CpGs of BDNF gene's promoter, PT did not yield any significant difference in methylation of BDNF CpGs as compared to non-exercised SE mice. In conclusion, PT increases hippocampal neurogenesis through increasing BDNF levels by some pathways other than demethylating BDNF CpGs and causes post SE newly-born neurons to integrate into normal circuits thus resulting in decreased spontaneous recurrent seizures and enhanced spatial memory.

Treadmill exercise improves memory function by inhibiting hippocampal apoptosis in pilocarpine-induced epileptic rats

Epilepsy is characterized by recurrent seizures and loss of neurons with abnormal rhythmic firing in the brains. In the present study, we investigated the effect of treadmill exercise on memory function in relation with cell proliferation and apoptosis in the hippocampus using pilocarpine-induced seizure rats. Epilepsy was initiated by intraperitoneal injection of pilocarpine hydrochloride. The rats in the exercise group were forced to run on a motorized treadmill for 30 min once a day for 2 weeks. In the present results, treadmill exercise alleviated short-term and spatial learning memory impairments in the epileptic rats. Treadmill exercise suppressed neuronal degeneration and enhanced neuronal maturation in the epileptic rats. Treadmill exercise suppressed cell proliferation and apoptosis in the epileptic rats. Treadmill exercise alleviated pilocarpine-induced memory impairments and suppressed neuronal loss in the hippocampus through down-regulation of apoptosis. These findings offer a possibility that treadmill exercise may provide a preventive or therapeutic value to the epilepsy-induced learning and memory impairments.

Systematic review and meta-analysis of the efficacy of different exercise programs in pilocarpine induced status epilepticus models

PURPOSE

To conduct a systematic review and meta-analysis of studies testing exercise in animal models of pilocarpine induced status epilepticus (SE) and to compare the efficacy of different training strategies used in those studies.

METHODS

We searched 2 online databases (Pubmed and Web of Science) for studies analyzing the efficacy of different trainings in pilocarpine-induced SE models. Training was categorized into forced physical training (PT), voluntary PT and resistance PT. Two reviewers independently extracted data on study quality, behavioral seizures, and histological, chemical and cognitive outcomes. Data were pooled by means of a meta-analysis.

RESULTS

Among 17 selected studies; 174 animals from 8 studies with 10 comparison groups showed that exercise intervention after induction of SE significantly decreased spontaneous recurrent seizures with [mean difference (MD)=-1.80, 95% confidence interval (CI): -3.22, -0.37, p=0.02] and 60 animals showed statistically significant decrease in latency in Morris water maze (standardized mean difference (SMD)=-2.57, 95% CI: -4.06, -1.08, p=0.0007). Although not statistically significant, still a remarkable increase in number of CA1 neurons and hippocampal BDNF level (MD=2.27, [95% CI: -1.20, 5.73], p=0.19, SMD=1.07, [95% CI: -0.36, 2.51], p=0.14 respectively) and a decrease in mossy fibers sprouting (SMD=-1.03, [95% CI: -3.06, 1.00], p=0.32) were observed. PT interventions in 72 animals before induction of SE showed favorable increase in latency to develop SE (MD=8.34, [95% CI: -3.10, 19.78], p=0.15) but no remarkable improvements in latency for the first motor sign and motor signs intensity.

CONCLUSIONS

PT after SE reduces the recurrent seizures and improves the morphological, biochemical and cognitive profiles of pilocarpine epileptic models. Resistance PT was identified as particularly effective in reducing behavioral seizures. The efficacy of training was also dependent upon duration.

Effect of endurance training on seizure susceptibility, behavioral changes and neuronal damage after kainate-induced status epilepticus in spontaneously hypertensive rats

The therapeutic efficacy of regular physical exercises in an animal model of epilepsy and depression comorbidity has been confirmed previously. In the present study, we examined the effects of endurance training on susceptibility to kainate (KA)-induced status epilepticus (SE), behavioral changes and neuronal damage in spontaneously hypertensive rats (SHRs). Male SHRs were randomly divided into two groups. One group was exercised on a treadmill with submaximal loading for four weeks and the other group was sedentary. Immediately after the training period, SE was evoked in half of the sedentary and trained rats by KA, while the other half of the two groups received saline. Basal systolic (SP), diastolic (DP) and mean arterial pressure (MAP) of all rats were measured at the beginning and at the end of the training period. Anxiety, memory and depression-like behaviour were evaluated a month after SE. The release of 5-HT in the hippocampus was measured using a liquid scintillation method and neuronal damage was analyzed by hematoxylin and eosin staining. SP and MAP of exercised SHRs decreased in comparison with the initial values. The increased resistance of SHRs to KA-induced SE was accompanied by an elongated latent seizure-free period, improved object recognition memory and antidepressant effect after the training program. While the anticonvulsant and positive behavioral effects of endurance training were accompanied by an increase of 5-HT release in the hippocampus, it did not exert neuroprotective activity. Our results indicate that prior exercise is an effective means to attenuate KA-induced seizures and comorbid behavioral changes in a model of hypertension and epilepsy suggesting a potential influence of hippocampal 5-HT on a comorbid depression. However, this beneficial impact does not prevent the development of epilepsy and concomitant brain damage.

Beneficial influence of physical exercise following status epilepticus in the immature brain of rats

Studies in adult animals have demonstrated a beneficial effect of physical exercise on epileptic insults. Although the effects of physical exercise on the mature nervous system are well documented, its influence on the developing nervous system subjected to injuries in childhood has been little explored. The purpose of our study was to investigate whether a physical exercise program applied during brain development could influence the hippocampal plasticity of rats submitted to status epilepticus (SE) induced by pilocarpine model at two different ages of the postnatal period. Male Wistar rats aged 18 (P18) and 28 (P28) days were randomly divided into four groups: Control (CTRL), Exercise (EX), SE (SE) and SE Exercise (SE/EX) (n=17 per group). After the aerobic exercise program, histological and behavioral (water maze) analyses were performed. Our results showed that only animals subjected to pilocarpine-induced SE at P28 presented spontaneous seizures during the observational period. A significant reduction in seizure frequency was observed in the SE/EX group compared to the SE group. In adulthood, animals submitted to early-life SE displayed impairment in long-term memory in the water maze task, while the exercise program reversed this deficit. Reduced mossy fiber sprouting in the dentate gyrus was noted in animals that presented spontaneous seizures (SE/EX vs SE). Exercise increased cell proliferation (Ki-67 staining) and anti-apoptotic response (bcl-2 staining) and reduced pro-apoptotic response (Bax staining) in animals of both ages of SE induction (P18/28). Exercise also modified the brain-derived neurotrophic factor (BDNF) levels in EX and SE/EX animals. Our findings indicate that in animals subjected to SE in the postnatal period a physical exercise program brings about beneficial effects on seizure frequency and hippocampal plasticity in later stages of life.

Effect of low-intensity treadmill exercise on behavioural measures and hippocampal parvalbumin immunoreactivity in the rat

Exercise has been demonstrated to have positive effects on both the body and brain. The present study aimed to determine the behavioural and morphological consequence of low-intensity running. Rats were exercised on a treadmill for a total of 30 days, 30 min/day. Social interaction, locomotor activity and behaviour on an elevated plus maze were assessed post-treatment. Exercised animals demonstrated more passive interaction and less time not interacting than control animals that were not exercised. Conversely, locomotor and anxiety measures showed no effect of exercise. Analysis of brains demonstrated an increase in expression of parvalbumin immunoreactive neurons in the hippocampus localised to the CA1 and CA2/3 regions. These results demonstrate that low-intensity exercise leads to changes in social behaviour as well as neuroplastic morphological changes within the hippocampus.