Akimasa Ishida

Low-speed treadmill running exercise improves memory function after transient middle cerebral artery occlusion in rats

Physical exercise may enhance the recovery of impaired memory function in stroke rats. However the appropriate conditions of exercise and the mechanisms underlying these beneficial effects are not yet known. Therefore, the purpose of this study was to investigate the effect exercise intensity on memory function after cerebral infarction in rats. The animals were subjected to middle cerebral artery occlusion (MCAO) for 90 min to induce stroke and were randomly assigned to four groups; Low-Ex, High-Ex, Non-Ex and Sham. On the fourth day after surgery, rats in the Low-Ex and High-Ex groups were forced to exercise using a treadmill for 30 min every day for four weeks. Memory functions were examined during the last 5 days of the experiment (27-32 days after MCAO) by three types of tests: an object recognition test, an object location test and a passive avoidance test. After the final memory test, the infarct volume, number of neurons and microtubule-associated protein 2 (MAP2) immunoreactivity in the hippocampus were analyzed by histochemistry. Memory functions in the Low-Ex group were improved in all tests. In the High-Ex group, only the passive avoidance test improved, but not the object recognition or object location tests. Both the Low-Ex and High-Ex groups had reduced infarct volumes. Although the number of neurons in the hippocampal dentate gyrus of the Low-Ex and High-Ex groups was increased, the number for the Low-Ex group increased more than that for the High-Ex group. Moreover hippocampal MAP2 immunoreactivity in the High-Ex group was reduced compared to that in the Low-Ex group. These data suggest that the effects of exercise on memory impairment after cerebral infarction depend on exercise intensity.

Treadmill running improves motor function and alters dendritic morphology in the striatum after collagenase-induced intracerebral hemorrhage in rats

It is well known that early rehabilitation is effective for functional recovery after intracerebral hemorrhage (ICH); however, the mechanisms have not been well described. The purpose of this study was to elucidate the effects of early rehabilitative therapy (treadmill running) on recovery of motor function and alteration of brain histology after ICH. Male Wistar rats, under deep anesthesia, were placed in a stereotaxic apparatus and injected with collagenase into the left striatum to induce ICH. Sham operated animals were treated with saline. All animals were randomly assigned to treadmill exercise (for 30 min/day, 9 m/min, between 4 and 14 days after surgery) and control and were designated to one of four groups: sham+control (SC), sham+treadmill (ST), ICH+control (IC), ICH+treadmill (IT). Motor deficit score (MDS) was assessed daily after surgery. Volume of tissue lost, dendritic morphology and PSD-95 protein level in the striatum were analyzed at 15 days after surgery. The MDS of IT was significantly improved compared with IC over time. There were no differences between IT and IC in the volume of tissue lost (IT: 63.8%, IC: 61.8%), spine density or PSD-95 protein level in the striatum. However, dendritic length was increased and arborization was more complex in the contralateral striatum of the IT than the IC group (IT: 1226 μm, IC: 937 μm). These data suggest that treadmill running improves motor function after ICH and that improvement may be related to alteration of dendritic morphology in the striatum.

Motor skills training promotes motor functional recovery and induces synaptogenesis in the motor cortex and striatum after intracerebral hemorrhage in rats

We investigated the effects of motor skills training on several types of motor function and synaptic plasticity following intracerebral hemorrhage (ICH) in rats. Male Wistar rats were injected with collagenase into the left striatum to induce ICH, and they were randomly assigned to the ICH or sham groups. Each group was divided into the motor skills training (acrobatic training) and control (no exercise) groups. The acrobatic group performed acrobatic training from 4 to 28 days after surgery. Motor functions were assessed by motor deficit score, the horizontal ladder test and the wide or narrow beam walking test at several time points after ICH. The number of ΔFosB-positive cells was counted using immunohistochemistry to examine neuronal activation, and the PSD95 protein levels were analyzed by Western blotting to examine synaptic plasticity in the bilateral sensorimotor cortices and striata at 14 and 29 days after ICH. Motor skills training following ICH significantly improved gross motor function in the early phase after ICH and skilled motor coordinated function in the late phase. The number of ΔFosB-positive cells in the contralateral sensorimotor cortex in the acrobatic group significantly increased compared to the control group. PSD95 protein expression in the motor cortex significantly increased in the late phase, and in the striatum, the protein level significantly increased in the early phase by motor skills training after ICH compared to no training after ICH. We demonstrated that motor skills training improved motor function after ICH in rats and enhanced the neural activity and synaptic plasticity in the striatum and sensorimotor cortex.

Early onset of forced impaired forelimb use causes recovery of forelimb skilled motor function but no effect on gross sensory-motor function after capsular hemorrhage in rats

Intensive use of the impaired forelimb promotes behavioral recovery and induces plastic changes of the central nervous system after stroke. However, the optimal onset of intensive use treatment after stroke is controversial. In this study, we investigated whether early forced impaired limb use (FLU) initiated 24h after intracerebral hemorrhage (ICH) of the internal capsule affected behavioral recovery and histological damage. Rats were subjected to ICH via low-dose collagenase infusion or sham stroke. One day after surgery, the ipsilateral forelimbs of half of the ICH and sham rats were casted for a week to induce the use of their contralateral forelimbs. Behavioral assessments were performed on days 10-12 and 26-28 after the surgery and followed by histological assessments. Improvements in skilled reaching and coordinated stepping function were found in the FLU-treated group in comparison with the untreated group after ICH. Additionally, FLU-treated ICH animals showed more normal and precise reaching and stepping movements as compared with ICH control animals. In contrast, FLU did not have a significant impact on gross sensory-motor functions such as the motor deficit score, contact placing response and spontaneous usage of the impaired paw. The volume of tissue lost and the number of spared corticospinal neurons in lesioned motor cortex were not affected by early FLU after ICH. These findings demonstrate the efficacy of early focused use of an impaired limb after internal capsule hemorrhage.

Early constraint-induced movement therapy promotes functional recovery and neuronal plasticity in a subcortical hemorrhage model rat

Constraint-induced movement therapy (CIMT) promotes functional recovery of impaired forelimbs after hemiplegic strokes, including intracerebral hemorrhage (ICH). We used a rat model of subcortical hemorrhage to compare the effects of delivering early or late CIMT after ICH. The rat model was made by injecting collagenase into the globus pallidus near the internal capsule, and then forcing rats to use the affected forelimb for 7 days starting either 1 day (early CIMT) or 17 days (late CIMT) after the lesion. Recovery of forelimb function in the skilled reaching test and the ladder stepping test was found after early-CIMT, while no significant recovery was shown after late CIMT or in the non-CIMT controls. Early CIMT was associated with greater numbers of ΔFosB-positive cells in the ipsi-lesional sensorimotor cortex layers II-III and V. Additionally, we found expression of the growth-related genes brain-derived neurotrophic factor (BDNF) and growth-related protein 43 (GAP-43), and abundant dendritic arborization of pyramidal neurons in the sensorimotor area. Similar results were not detected in the contra-lesional cortex. In contrast to early CIMT, late CIMT failed to induce any changes in plasticity. We conclude that CIMT induces molecular and morphological plasticity in the ipsi-lesional sensorimotor cortex and facilitates better functional recovery when initiated immediately after hemorrhage.

Minor neuronal damage and recovered cellular proliferation in the hippocampus after continuous unilateral forelimb restraint in normal rats.

Constraint‐induced movement therapy (CIMT) involves the restraint of an intact limb to force the dominant use of an affected limb, in an attempt to enhance use‐dependent plasticity and reduce dysfunction. To investigate whether forced disuse of an intact forelimb with CIMT causes a loss of limb function and degenerative damage in the brain, a staircase test and a horizontal ladder test were carried out in control rats and forelimb‐restrained rats, and then Argyrophil III silver staining, which is capable of detecting subtle neuronal damage, was used to examine histological alterations associated with restraint. No significant changes in forelimb function were observed in restrained rats. However, atypical weak argyrophilic neurons, an indicator of minor neural damage, were found in the bilateral hippocampus of restrained rats. This damage was not found in the cortex, striatum, or spinal cord. Investigation of neurogenesis in the subventricular zone (SVZ) and subgranular zone (SGZ) revealed a clear reduction in the number of bromodeoxyuridine‐positive cells in bilateral SGZ, but not in the SVZ, in restrained rats compared with controls. This reduction was accompanied by reduced mRNA expression of vascular endothelial growth factor and glial‐derived neurotrophic factor. However, reduced cellular proliferation and decreased gene expression were recovered after the removal of the restraint. Our results suggest that forced disuse of the intact forelimb has no significant effect on skilled forelimb function but has a minor effect on neurogenesis in SGZ, suggesting that mild stress may be caused by the restraint.

Alterations of Both Dendrite Morphology and Weaker Electrical Responsiveness in the Cortex of Hip Area Occur Before Rearrangement of the Motor Map in Neonatal White Matter Injury Model

Hypoxia-ischemia (H-I) in rats at postnatal day 3 causes disorganization of oligodendrocyte development in layers II/III of the sensorimotor cortex without apparent neuronal loss, and shows mild hindlimb dysfunction with imbalanced motor coordination. However, the mechanisms by which mild motor dysfunction is induced without loss of cortical neurons are currently unclear. To reveal the mechanisms underlying mild motor dysfunction in neonatal H-I model, electrical responsiveness and dendrite morphology in the sensorimotor cortex were investigated at 10 weeks of age. Responses to intracortical microstimulation (ICMS) revealed that the cortical motor map was significantly changed in this model. The cortical area related to hip joint movement was reduced, and the area related to trunk movement was increased. Sholl analysis in Golgi staining revealed that layer I–III neurons on the H-I side had more dendrite branches compared with the contralateral side. To investigate whether changes in the motor map and morphology appeared at earlier stages, ICMS and Sholl analysis were also performed at 5 weeks of age. The minimal ICMS current to evoke twitches of the hip area was higher on the H-I side, while the motor map was unchanged. Golgi staining revealed more dendrite branches in layer I–III neurons on the H-I side. These results revealed that alterations of both dendrite morphology and ICMS threshold of the hip area occurred before the rearrangement of the motor map in the neonatal H-I model. They also suggest that altered dendritic morphology and altered ICMS responsiveness may be related to mild motor dysfunction in this model.

Monosodium glutamate ingestion during the development period reduces aggression mediated by the vagus nerve in a rat model of attention deficit–hyperactivity disorder

We used an umami substance, monosodium glutamate (MSG), as a simple stimulant to clarify the mechanism of the formation of emotional behavior. A 60 mM MSG solution was fed to spontaneously hypertensive rats (SHR), used as a model of attention-deficit hyperactivity disorder, from postnatal day 25 for 5 weeks kept in isolation. Emotional behaviors (anxiety and aggression) were then assessed by the open-field test, cylinder test and social interaction test. MSG ingestion during the developmental period resulted in a significant reduction in aggressive behavior but had few effects on anxiety-like behavior. Several experiments were performed to identify the reason for the reduced aggression with MSG intake. Blood pressure in the MSG-treated SHR was comparable to that of the controls during development. Argyrophil III staining to detect the very early phase of neuronal damage revealed no evidence of injury by MSG in aggression-related brain areas. Assessment of plasma amino acids revealed that glutamate levels remained constant (∼80 μM) with MSG ingestion, except for a transient increase after fasting (∼700 μM). However, lactate dehydrogenase assay in an in vitro blood-brain barrier model showed that cell toxicity was not induced by indirect MSG application even at 700 μM, confirming that MSG ingestion caused minimal neuronal damage. Finally, vagotomy at the sub-diaphragmatic level before MSG ingestion blocked its effect on aggressive behavior in the isolated SHR. The data suggest that MSG ingestion during the developmental period can reduce aggressive behavior in an attention deficit-hyperactivity disorder model rat, mediated by gut-brain interaction.

Forced-use of impaired forelimb increases expression of neurotrophic factors in rats motor cortex and induces recovery of skilled reaching and stepping following internal capsule hemorrhage

P2-f10 Forced-use of impaired forelimb increases expression of neurotrophic factors in rats motor cortex and induces recovery of skilled reaching and stepping following internal capsule hemorrhage Akimasa Ishida 1,2 , Yasuyuki Takamatsu 1, Michiru Hamakawa 1, Keigo Tamakoshi 1, Hideki Hida 2, Kazuto Ishida 1 1 Department Phys Ther., Nagoya University Grad. Sch. Med 2 Neurophysiol. and Brain Sci., Nagoya City University Grad. Sch. Med