The effect of a skilled reaching task on hippocampal plasticity after intracerebral hemorrhage in adult rats

Different training patterns at recovery stage improve cognitive function in ischemic stroke rats through regulation of the axonal growth inhibitor pathway

Running wheel exercise training (RWE) and skilled reaching training (SRT) are physical training approaches with positive effects on cognitive function. However, few studies have compared the different effects of these exercises on long-term memory, and their mechanism remains unknown. This study investigated the effects of SRT and RWE, at the recovery stage, on the cognitive function of transient middle cerebral artery occlusion (tMCAO) rats and explored their association with NgR1/Rho-A/ROCK/LOTUS/LGI1 signaling. Adult Sprague-Dawley rats (n = 55) were divided into four groups after pretraining: SRT, RWE, tMCAO, and Sham. Rats were subjected to modified neurological severity score (mNSS) measurements and forelimb grip strength and the Morris water maze tests. Using immunofluorescence and western blotting, we evaluated axonal growth inhibitor expression in the peri-infarct cortex on days 28 and 56 after tMCAO. Results showed the mNSS reduced, whereas the grip strengths improved in RWE and SRT groups. The escape latency in the Morris water maze test was shorter, whereas the number of times of crossing the platform was higher in both the SRT and RWE groups than in the tMCAO group on day 56; furthermore, the parameters in the SRT group improved compared to those in the RWE group. Physical exercise training could improve cognitive functions by reducing the expression of the NgR1/RhoA/ROCK axon growth inhibitors and increasing the expression of the endogenous antagonists LOTUS/LGI1. Exercise training beginning at the recovery stage could improve the cognitive function in tMCAO rats through a mechanism probably associated with the axonal growth inhibitor pathway.

Mini Review (Part I): An Experimental Concept on Exercise and Ischemic Conditioning in Stroke Rehabilitation

Stroke remains a leading cause of adult death and disability. Poststroke rehabilitation is vital for reducing the long-term sequelae of brain ischemia. Recently, physical exercise training has been well established as an effective rehabilitation tool, but its efficacy depends on exercise parameters and the patient's capacities, which are often altered following a major cerebrovascular event. Thus, ischemic conditioning as a rehabilitation intervention was considered an “exercise equivalent,” but the investigation is still in its relative infancy. In this mini-review, we discuss the potential for physical exercise or ischemic conditioning and its relation to angiogenesis, neurogenesis, and plasticity in stroke rehabilitation. This allows the readers to understand the context of the research and the application of ischemic conditioning in poststroke rehabilitation.

Arundic Acid (ONO-2506), an Inhibitor of S100B Protein Synthesis, Prevents Neurological Deficits and Brain Tissue Damage Following Intracerebral Hemorrhage in Male Wistar Rats

Stroke is one of the leading causes of mortality and neurological morbidity. Intracerebral hemorrhage (ICH) has the poorest prognosis among all stroke subtypes and no treatment has been effective in improving outcomes. Following ICH, the observed high levels of S100B protein have been associated with worsening of injury and neurological deficits. Arundic acid (AA) exerts neuroprotective effects through inhibition of astrocytic synthesis of S100B in some models of experimental brain injury; however, it has not been studied in ICH. The aim of this study was to evaluate the effects of intracerebroventricular (ICV) administration of AA in male Wistar rats submitted to ICH model assessing the following variables: reactive astrogliosis, S100B levels, antioxidant defenses, cell death, lesion extension and neurological function. Firstly, AA was injected at different doses (0.02, 0.2, 2 and 20 μg/μl) in the left lateral ventricle in order to observe which dose would decrease GFAP and S100B striatal levels in non-injured rats. Following determination of the effective dose, ICH damage was induced by IV-S collagenase intrastrial injection and 2 μg/μl AA was injected through ICV route immediately before injury. AA treatment prevented ICH-induced neurological deficits and tissue damage, inhibited excessive astrocytic activation and cellular apoptosis, reduced peripheral and central S100B levels (in striatum, serum and cerebrospinal fluid), improved neuronal survival and enhanced the antioxidant defences after injury. Altogether, these results suggest that S100B is a viable target for treating ICH and highlight AA as an interesting strategy for improving neurological outcome after experimental brain hemorrhage.

Modulation of Synaptic Plasticity by Exercise Training as a Basis for Ischemic Stroke Rehabilitation

In recent years, rehabilitation of ischemic stroke draws more and more attention in the world, and has been linked to changes of synaptic plasticity. Exercise training improves motor function of ischemia as well as cognition which is associated with formation of learning and memory. The molecular basis of learning and memory might be synaptic plasticity. Research has therefore been conducted in an attempt to relate effects of exercise training to neuroprotection and neurogenesis adjacent to the ischemic injury brain. The present paper reviews the current literature addressing this question and discusses the possible mechanisms involved in modulation of synaptic plasticity by exercise training. This review shows the pathological process of synaptic dysfunction in ischemic roughly and then discusses the effects of exercise training on scaffold proteins and regulatory protein expression. The expression of scaffold proteins generally increased after training, but the effects on regulatory proteins were mixed. Moreover, the compositions of postsynaptic receptors were changed and the strength of synaptic transmission was enhanced after training. Finally, the recovery of cognition is critically associated with synaptic remodeling in an injured brain, and the remodeling occurs through a number of local regulations including mRNA translation, remodeling of cytoskeleton, and receptor trafficking into and out of the synapse. We do provide a comprehensive knowledge of synaptic plasticity enhancement obtained by exercise training in this review.