Effect of aerobic physical exercise in pinealectomized animals submitted to the pilocarpine model of epilepsy

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.

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.

Physical exercise program reverts the effects of pinealectomy on the amygdala kindling development

Several studies have demonstrated the anticonvulsant effect of melatonin. In view of the positive effects of physical exercise in epilepsy, this study analyzed the influence of physical exercise program on the amygdala kindling development in pinealectomized rats. Animals were divided into six groups: pinealectomized rats (PX), sham rats (SHAM), control rats (CTL), pinealectomized rats submitted to an aerobic exercise program (PX ATL), sham rats submitted to an aerobic exercise program (SHAM ATL) and control rats submitted to an aerobic exercise program (CTL ATL). The stimulus parameters consisted of 60 Hz frequency, diphasic square pulses of 1 ms duration applied for 2 s. The mean number of stimulations and the after-discharge (AD) duration for each stage of kindling were similar among CTL and SHAM animals. PX animals showed particular characteristics during kindling development. They did not present stage 1 and spent a shorter time in stage 2 in relation to the CTL and SHAM animals. Consequently, the AD duration and number of stimulations required to reach stage 5 was lower for the PX group when compared to the CTL and SHAM groups. Concerning the exercising groups, CTL ATL and SHAM ATL animals spent a higher time in stage 1 compared to CTL and SHAM groups. Thus, CTL ATL animals also presented a higher number of stimulations in stage 5 compared to CTL animals. The stage 1 not observed in PX animals was present in PX ATL. Consequently, the number of stimulations required to reach stage 5 was statistically higher for the PX ATL group in relation to the PX group. Our results demonstrate that the acceleration in the kindling development of pinealectomized animals can be reverted by physical exercise.