Impaired motor activity and motor learning function in rat with middle cerebral artery occlusion

The benefits of high-intensity physical exercise before and after Parkinson's disease induction in rats

High-intensity physical activity is a non-pharmacological intervention that has been tested as a treatment for Parkinson's disease (PD). The objective of the study was to investigate the benefits of high-intensity physical exercise on the number of neurons and astrocytes in a a rat model of Parkinson's disease submitted to training before and after the inducing injury. Seventy Wistar rats were used, distributed as follows: nine rats trained before PD induction (DP-Exa), nine trained after PD induction (DP-Exd), 10 trained before and after PD induction (DP-Exad), and nine sedentary rats (DP-Sed). There were also the same groups but with the rats exposed to the sham surgery (control). High-intensity physical exercise on a vertical ladder was performed before and/or after PD induction for 5 days/week, 30-45 min a day, for 4 weeks. PD was induced with an electrolytic lesion (AP -4.9, ML 1.7, and DV 8.1). At the end of the experiment, the brain was removed for Nissl staining and immunohistochemistry of glial fibrillary acidid protein (GFAP) in the substantia nigra and striatum. The DP-Exa, Sham-Exa, DP-Exad, and Sham-Exad groups showed a greater number of neurons and higher expression of GFAP in the substantia nigra and stiatum compared with the the DP-Exd, Sham-Exd, DP-Sed, and Sham-Sed groups. Thus, rats that performed high-intensity training before or before and after PD induction had higher densities of neurons and astrocytes.

IL-17A exacerbates caspase-12-dependent neuronal apoptosis following ischemia through the Src-PLCγ-calpain pathway

Interleukin-17 A (IL-17 A) contributes to inflammation and causes secondary injury in post-stroke patients. However, little is known regarding the mechanisms that IL-17 A is implicated in the processes of neuronal death during ischemia. In this study, the mouse models of middle cerebral artery occlusion/reperfusion (MCAO/R)-induced ischemic stroke and oxygen-glucose deprivation/reoxygenation (OGD/R)-simulated in vitro ischemia in neurons were employed to explore the role of IL-17 A in promoting neuronal apoptosis. Mechanistically, endoplasmic reticulum stress (ERS)-induced neuronal apoptosis was accelerated by IL-17 A activation through the caspase-12-dependent pathway. Blocking calpain or phospholipase Cγ (PLCγ) inhibited IL-17 A-mediated neuronal apoptosis under ERS by inhibiting caspase-12 cleavage. Src and IL-17 A are linked, and PLCγ directly binds to activated Src. This binding causes intracellular Ca2+ flux and activates the calpain-caspase-12 cascade in neurons. The neurological scores showed that intracerebroventricular (ICV) injection of an IL-17 A neutralizing mAb decreased the severity of I/R-induced brain injury and suppressed apoptosis in MCAO mice. Our findings reveal that IL-17 A increases caspase-12-mediated neuronal apoptosis, and IL-17 A suppression may have therapeutic potential for ischemic stroke.

Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway

Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.

Motor deficits are associated with increased glial cell activation in the hypothalamus and cerebellum of young rats subjected to cerebral palsy

Cerebral palsy (CP) is a syndrome characterized by a wide range of sensory and motor damage, associated with behavioral and cognitive deficits. The aim of the present study was to investigate the potential of a model of CP using a combination of perinatal anoxia and sensorimotor restriction of hind paws to replicate motor, behavioral and neural deficits. A total of 30 of male Wistar rats were divided into Control (C, n = 15), and CP (CP, n = 15) groups. The potential of the CP model was assessed by evaluating food intake, the behavioral satiety sequence, performance on the CatWalk and parallel bars, muscle strength, and locomotor activity. The weight of the encephalon, soleus, and extensor digitorum longus (EDL) muscles, and the activation of glial cells (microglia and astrocytes) were also measured. The CP animals showed delayed satiety, impaired locomotion on the CatWalk and open field test, reduced muscle strength, and reduced motor coordination. CP also reduced the weight of the soleus and muscles, brain weight, liver weight, and quantity of fat in various parts of the body. There was also found to be an increase in astrocyte and microglia activation in the cerebellum and hypothalamus (arcuate nucleus, ARC) of animals subjected to CP.

Rat BM-MSCs secretome alone and in combination with stiripentol and ISRIB, ameliorated microglial activation and apoptosis in experimental stroke

BACKGROUND

Stroke, a devastating neurological emergency, is the leading cause of worldwide mortality and functional disability. Combining novel neuroprotective drugs offers a way to improve the stroke intervention outcomes. In the present era, the combination therapy has been proposed as a plausible strategy to target multiple mechanisms and enhance the treatment efficacy to rescue stroke induced behavioral abnormalities and neuropathological damage. In the current study, we have investigated the neuroprotective effect of stiripentol (STP) and trans integrated stress response inhibitor (ISRIB) alone and in combination with rat bone marrow derived mesenchymal stem cells (BM-MSCs) secretome in an experimental model of stroke.

MATERIALS & METHODS

Stroke was induced in male Wistar rats (n=92) by temporary middle cerebral artery occlusion (MCAO). Three investigational agents were selected including STP (350mg/kg; i.p.), trans ISRIB (2.5mg/kg; i.p.) and rat BM-MSCs secretome (100µg/kg; i.v). Treatment was administered at 3 hrs post MCAO, in four doses with a 12 hrs interval. Post MCAO, neurological deficits, brain infarct, brain edema, BBB permeability, motor functional and memory deficits were assessed. Molecular parameters: oxidative stress, pro inflammatory cytokines, synaptic protein markers, apoptotic protein markers and histopathological damage were assessed.

RESULTS

STP and trans ISRIB, alone and in combination with rat BM-MSCs secretome, significantly improved neurological, motor function and memory deficits along with significant reduction in pyknotic neurons in the brain of post MCAO rats. These results were correlating with significant reduction in pro-inflammatory cytokines, microglial activation and apoptotic markers in the brain of drug treated post MCAO rats.

CONCLUSION

STP and trans ISRIB, alone and in combination with rat BM-MSCs secretome, might be considered as potential neuroprotective agents in the acute ischemic stroke (AIS) management.

DATA AVAILABILITY STATEMENT

Data will be made available on reasonable request.

Epigallocatechin gallate alleviates neuronal cell damage against focal cerebral ischemia in rats

Cerebral ischemia is a neurological disorder that causes permanent disability and is sometimes fatal. Epigallocatechin gallate (EGCG) is a natural polyphenol that exerts beneficial antioxidant and anti-inflammatory effects. The aim of this study was to investigate the neuroprotective effects of EGCG against cerebral ischemia. Middle cerebral artery occlusion was surgically initiated to induce focal cerebral ischemia in adult male rats. EGCG (50 mg/kg) or vehicle was intraperitoneally injected just prior to middle cerebral artery occlusion (MCAO) induction. Neuronal behavior tests were performed 24 hr after MCAO. Brain tissues were isolated to evaluate infarct volume, histological changes, apoptotic cell death, and caspase-3 and poly ADP-ribose polymerase (PARP) levels. MCAO injury led to serious functional neurological deficits and increased infarct volume. Moreover, it induced histopathological lesions and increased the numbers of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells in the cerebral cortex. However, EGCG improved MCAO-induced neurological deficits and reduced infarct volume, alleviated histopathological changes, and decreased TUNEL-positive cells in the cerebral cortex of MCAO rats. Western blot analysis showed increases of caspase-3 and PARP expression levels in MCAO rats with vehicle, whereas EGCG administration alleviated these increases after MCAO injury. These results demonstrate that EGCG exerts a neuroprotective effect by regulating caspase-3 and PARP proteins during cerebral ischemia. In conclusion, we suggest that EGCG acts as a potent neuroprotective agent by modulating the apoptotic signaling pathway.

IL-17A-Mediated Excessive Autophagy Aggravated Neuronal Ischemic Injuries via Src-PP2B-mTOR Pathway

We previously reported that astrocyte-derived proinflammatory cytokine interleukin (IL)-17A could aggravate neuronal ischemic injuries and strength autophagy both in oxygen-glucose deprivation (OGD)/reoxygenation (R)-treated neurons and peri-infarct region of mice with middle cerebral artery occlusion (MCAO)/reperfusion (R)-simulated ischemic stroke. In this study, the role and molecular mechanism of IL-17A in autophagy were further explored under ischemic condition. We found that exogenous addition of rmIL-17A remarkably (P < 0.001) decreased cell viability, which companying with the increases of LC3 II accumulation (P < 0.05 or 0.01) and Beclin 1 levels (P < 0.05 or 0.001), and reduction of p62 levels (P < 0.01 or 0.001) in OGD/R-treated cortical neurons (n = 6). The levels of P-mTOR (Ser 2448) (P < 0.001) and P-S6 (Ser 240/244) (P < 0.01) significantly decreased without the involvement of Akt, ERK1/2 and AMPK in cortical neurons under rmIL-17A and OGD/R treatments (n = 6). Interestingly, the co-IP analysis exhibited that PP2B and mTOR could be reciprocally immunoprecipitated; and the addition of rmIL-17A increased their interactions, PP2B activities (P < 0.001), P-Src (P < 0.001), and P-PLCγ1 (P < 0.01) levels in OGD/R-treated neurons (n = 6 or 5). The PP2B inhibitor Cyclosporin A blocked the induction of excessive autophagy (P < 0.05 or <0.001) and increased cell viability (P < 0.001) after OGD/R and rmIL-17A treatments (n = 6). In addition, the ICV injection of IL-17A neutralizing mAb could attenuate autophagy levels (P < 0.01 or 0.001, n = 6) and improve neurological functions (P < 0.01 or 0.001, n = 10) of mice after 1 h MCAO/R 24 h or 7 d. These results suggested that IL-17A-mediated excessive autophagy aggravates neuronal ischemic injuries via Src-PP2B-mTOR pathway, and IL-17A neutralization may provide a potential therapeutic effect for ischemic stroke.

Effects of physical exercise on skeletal muscles of rats with cerebral ischemia

Physical exercise is a known preventive and therapeutic alternative for several cerebrovascular diseases. Therefore, the objective of the present study was to evaluate the motor performance and histomorphometry of the biceps brachii, soleus, and tibialis anterior muscles of rats submitted to a treadmill training program prior to the induction of cerebral ischemia via occlusion of the middle cerebral artery (OMCA). A total of 24 Wistar rats were distributed into four groups: Sham-Sed: sedentary control animals (n=6), who underwent sham surgery (in which OMCA did not occur); Sham+Ex: control animals exercised before the sham surgery (n=6); I-Sed: sedentary animals with cerebral ischemia (n=6); and I+Ex: animals exercised before the induction of ischemia (n=6). The physical exercise consisted of treadmill training for five weeks, 30 min/day (5 days/week), at a speed of 14 m/min. The results showed that the type-I fibers presented greater fiber area in the exercised ischemic group (I+Ex: 2347.96±202.77 µm2) compared to the other groups (Sham-Sed: 1676.46±132.21 µm2; Sham+Ex: 1647.63±191.09 µm2; I+Ex: 1566.93±185.09 µm2; P=0.0002). Our findings suggested that the angiogenesis process may have influenced muscle recovery and reduced muscle atrophy of type-I fibers in the animals that exercised before cerebral ischemia.

Curcumin protects dopaminergic neurons against inflammation-mediated damage and improves motor dysfunction induced by single intranigral lipopolysaccharide injection

Various studies have indicated a lower incidence and prevalence of neurological conditions in people consuming curcumin. The ability of curcumin to target multiple cascades, simultaneously, could be held responsible for its neuroprotective effects. The present study was designed to investigate the potential of curcumin in minimizing microglia-mediated damage in lipopolysaccharide (LPS) induced model of PD. Altered microglial functions and increased inflammatory profile of the CNS have severe behavioral consequences. In the current investigation, a single injection of LPS (5 ug/5 µl PBS) was injected into the substantia nigra (SN) of rats, and curcumin [40 mg/kg b.wt (i.p.)] was administered daily for a period of 21 days. LPS triggered an inflammatory response characterized by glial activation [Iba-1 and glial fibrillary acidic protein (GFAP)] and pro-inflammatory cytokine production (TNF-α and IL-1β) leading to extensive dopaminergic loss and behavioral abnormality in rats. The behavioral observations, biochemical markers, quantification of dopamine and its metabolites (DOPAC and HVA) using HPLC followed by IHC of tyrosine hydroxylase (TH) were evaluated after 21 days of LPS injection. Curcumin supplementation prevented dopaminergic degeneration in LPS-treated animals by normalizing the altered levels of biomarkers. Also, a significant improvement in TH levels as well as behavioral parameters (actophotometer, rotarod, beam walking and grid walking tests) were seen in LPS injected rats. Curcumin shielded the dopaminergic neurons against LPS-induced inflammatory response, which was associated with suppression of glial activation (microglia and astrocytes) and transcription factor NF-κB as depicted from RT-PCR and EMSA assay. Curcumin also suppressed microglial NADPH oxidase activation as observed from NADPH oxidase activity. The results suggested that one of the important mechanisms by which curcumin mediates its protective effects in the LPS-induced PD model is by inhibiting glial activation. Therefore, curcumin could be a potential therapeutic agent for inflammation-driven neurodegenerative disorders like PD, and its neuroprotective role should be explored further.

Apocyanin, NADPH oxidase inhibitor prevents lipopolysaccharide induced α-synuclein aggregation and ameliorates motor function deficits in rats: Possible role of biochemical and inflammatory alterations

Parkinson's disease (PD), is an age-related, progressive neurodegenerative disorder that affects movement and is characterized by the loss of dopaminergic neurons in the nigrostriatal region. Although the clinical and pathological features of PD are complex, recent studies have indicated that microglial NADPH oxidase play a key role in its pathology. A little information is available regarding the role of apocyanin, an NADPH oxidase inhibitor, in ameliorating α-synuclein aggregation and neurobehavioral consequences of PD. Therefore, the present study evaluated its therapeutic potentials for the treatment of neurobehavioral consequences in lipolysaccharide (LPS) induced PD model. For the establishment of PD model LPS (5 μg/5 μl PBS) was injected into the Substantia nigra (SN) of rats. Apocyanin (10mg/kgb.wt) was injected intraperitoneal. Statistical analysis revealed that apocynin significantly ameliorated LPS induced inflammatory response characterized by NFkB, TNF-α and IL-1β upregulation as assessed by ELISA. It also prevented dopaminergic neurons from toxic insult of LPS as indicated by inhibition of apoptotic markers i.e., caspase 3 and caspase 9 as depicted from RT-PCR and ELISA studies. This was further supported by TUNEL assay for DNA fragmentation. Effectiveness of apocyanin in protecting dopaminergic neuronal degeneration was further confirmed by assessment of α-synuclein deposition as depicted by IHC analysis. Consequently, an improvement in the behavioral outcome was observed following apocyanin treatment as depicted from various behavioral tests performed. Hence the data suggests that specific NADPH oxidase inhibitors, such as apocynin, may provide a new therapeutic approach to the control of neurological disabilities induced by LPS induced PD.

Characterization of the lipopolysaccharide induced model of Parkinson's disease: Role of oxidative stress and neuroinflammation

INTRODUCTION

Primary pathology underlying Parkinson's disease (PD) is the loss of dopaminergic neurons in the substantia nigra (SN). A variety of genetic and environmental factors underlie this loss of dopaminergic neurons. However, recent studies have highlighted the role of elevated oxidative stress and the pro-inflammatory responses contributing to or exacerbating the nigrostriatal degeneration.

METHODS

With the establishment of neuroinflammation as an important process involved in the PD pathogenesis, in the present study this pathogenic feature was replicated in animals using lipopolysaccharide (LPS) (5 ug/5 ul PBS) infused stereotaxically into the SN of rats.

RESULTS

LPS injected into the SN successfully replicated the pathogenic features of PD in rats as it elicited an inflammatory response via action of microglia. LPS infusion resulted in glial cell activation as depicted from immunohistochemistry (IHC) analysis of GFAP and Iba-1. Also, a significant increase in the mRNA expression of proinflammatory cytokines, i.e. TNF-α and IL-1β, was observed after 7 days of LPS infusion whereas the alterations in the oxidative stress markers, i.e ROS, lipid peroxidation, NO formation, NADPH oxidase activity, glutathione system, SOD and catalase, became highly significant after 14 days of infusion. As a consequence, after 21 days of LPS infusion we observed activation of apoptotic pathway indicated by increased expression of caspases 3 and caspase 9. This was followed by a significant decline in the expression of tyrosine hyroxylase (TH) as revealed by IHC. Further, there was a marked decrease in the level of dopamine and its metabolites enough for the production of behavioral abnormality in rats.

CONCLUSION

Hence, the present study provides extensive characterization of LPS induced model of PD. Study also confirms the co-existence and complex interplay between inflammation and oxidative stress contributing equally to the dopaminergic neuronal degeneration process in PD.

Role of neuronal NADPH oxidase 1 in the peri-infarct regions after stroke

The molecular mechanism underlying the selective vulnerability of neurons to oxidative damage caused by ischemia-reperfusion (I/R) injury remains unknown. We sought to determine the role of NADPH oxidase 1 (Nox1) in cerebral I/R-induced brain injury and survival of newborn cells in the ischemic injured region. Male Wistar rats were subjected to 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion. After reperfusion, infarction size, level of superoxide and 8-hydroxy-2'-deoxyguanosine (8-oxo-2dG), and Nox1 immunoreactivity were determined. RNAi-mediated knockdown of Nox1 was used to investigate the role of Nox1 in I/R-induced oxidative damage, neuronal death, motor function recovery, and ischemic neurogenesis. After I/R, Nox1 expression and 8-oxo-2dG immunoreactivity was increased in cortical neurons of the peri-infarct regions. Both infarction size and neuronal death in I/R injury were significantly reduced by adeno-associated virus (AAV)-mediated transduction of Nox1 short hairpin RNA (shRNA). AAV-mediated Nox1 knockdown enhanced functional recovery after MCAO. The level of survival and differentiation of newborn cells in the peri-infarct regions were increased by Nox1 inhibition. Our data suggest that Nox-1 may be responsible for oxidative damage to DNA, subsequent cortical neuronal degeneration, functional recovery, and regulation of ischemic neurogenesis in the peri-infarct regions after stroke.

Therapeutic efficacy of Neuro AiD™ (MLC 601), a traditional Chinese medicine, in experimental traumatic brain injury

Traumatic brain injury (TBI) causes increased release of several mediators from injured and dead cells and elicits microglial activation. Activated microglia change their morphology, migrate to injury sites, and release tumor necrosis factor-alpha (TNF-α) and others. In this study we used a controlled fluid percussion injury model of TBI in the rat to determine whether early (4 h post-injury) or late (4 days post-injury) treatment with MLC 601, a Traditional Chinese Medicine, would affect microglial activation and improve recovery. MLC 601 was chosen for this study because its herbal component MLC 901 was beneficial in treating TBI in rats. Herein, rats with induced TBI were treated with MLC 601 (0.2-0.8 mg/kg) 1 h (early treatment) or 4 day post-injury (late treatment) and then injected once daily for consecutive 2 days. Acute neurological and motor deficits were assessed in all rats the day before and 4 days after early MLC 601 treatment. An immunofluorescence microscopy method was used to count the numbers of the cells colocalized with neuron- and apoptosis-specific markers, and the cells colocalized with microglia- and TNF-α-specific markers, in the contused brain regions 4 days post-injury. An immunohistochemistry method was used to evaluate both the number and the morphological transformation of microglia in the injured areas. It was found that early treatment with MLC 601 had better effects in reducing TBI-induced cerebral contusion than did the late therapy with MLC 601. Cerebral contusion caused by TBI was associated with neurological motor deficits, brain apoptosis, and activated microglia (e.g., microgliosis, amoeboid microglia, and microglial overexpression of TNF-α), which all were significantly attenuated by MLC 601 therapy. Our data suggest that MLC 601 is a promising agent for treatment of TBI in rats.

Long-term neuroprotection induced by regional brain cooling with saline infusion into ischemic territory in rats: a behavioral analysis

The neuroprotective effect of hypothermia has long been recognized. Our recent studies have demonstrated the significant therapeutic value of local brain cooling in the ischemic territory prior to reperfusion in stroke, with reduced infarction and inflammatory responses up to 48 hours of reperfusion. The goal of this study was to determine if local brain cooling, produced by infusion of cold saline, could induce long-term functional improvement after stroke. A hollow filament was used to block the middle cerebral artery (MCA) for 3 hours, and then to locally infuse the ischemic territory with 6 ml cold saline (20 degrees C) for 10 minutes prior to reperfusion. This brain cooling infusion induced a significant (p < 0.01) decrease in neurologic deficits and significantly (p < 0.01) improved motor behavior in ischemic rats after 14 days of reperfusion, compared with ischemic rats without local cold saline infusion. This improvement continued for up to 28 days after reperfusion. No significant difference in motor performance was observed between the brain cooling infusion and normal control groups. Significant (p < 0.01) reductions in infarct volume were also evident. In conclusion, a local cerebral hypothermia induced by local saline infusion prior to reperfusion produced a long-term functional recovery after ischemic stroke. A therapeutic procedure, which combines prereperfusion infusion into an ischemic region with coincident cerebral hypothermia and perhaps subsequent recanalization of an occluded intracranial vessel, may improve the outcome for stroke patients.

Neuroprotection against transient cerebral ischemia by exercise pre-conditioning in rats

There is increasing evidence that physical activity is associated with decreased stroke risk and incidence. The purpose of this study was to determine whether increased levels of physical activity could reduce brain damage in rats subjected to transient or permanent middle cerebral artery (MCA) occlusion. Adult male Sprague-Dawley rats (three months old, n=36) exercised on a treadmill, which required repetitive locomotor movement, for 30 min each day for three weeks. Then, using an intraluminal filament, stroke was induced by either 2-h MCA occlusion followed by two days of reperfusion or by MCA occlusion for two days without reperfusion. Brain damage was determined by evaluating neurologic deficits and brain infarction. In rat with transient MCA occlusion, pre-ischemic motor activity significantly (p<0.01) reduced neurologic deficits and infarct volume in the frontoparietal cortex and the dorsolateral striatum. In contrast, the same exercise procedure did not produce neuroprotection in the permanently MCA-occluded stroke. In addition to decreasing stroke risk and incidence, physical activity also reduces brain damage after stroke. Although we cannot completely rule out a neuroprotective effect on ischemic episode, our study suggests that a major neuroprotection is conferred during reperfusion for rats that have undergone exercise pre-conditioning. This exercise-induced endogenous neuroprotection may be an effective strategy to ameliorate ischemia/reperfusion brain injury from stroke.

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.

Reduction of brain edema and expression of aquaporins with acute ethanol treatment after traumatic brain injury

OBJECT

Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema by allowing excessive water passage through aquaporin (AQP) proteins. To establish the potential neuroprotective properties of ethanol as a post-TBI therapy, in the present study the authors determined the effect of ethanol on brain edema, AQP expression, and functional outcomes in a post-TBI setting.

METHODS

Adult male Sprague-Dawley rats weighing between 425 and 475 g received a closed head TBI in which Maramarou's impact-acceleration method was used. Animals were given a subsequent intraperitoneal injection of 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI and were killed 24 hours after TBI. Brains were subsequently examined for edema along with AQP mRNA and protein expression. Additional animals treated with either 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI were designated for cognitive and motor testing for 3 weeks.

RESULTS

Ethanol administration post-TBI led to significantly (p < 0.05) lower levels of brain edema as measured by brain water content. This downregulation in brain edema was associated with significantly (p < 0.05) reduced levels of AQP mRNA and protein expression as compared with TBI without treatment. These findings concur with cognitive studies in which ethanol-treated animals exhibited significantly (p < 0.05) faster radial maze completion times. Motor behavioral testing additionally demonstrated significant (p < 0.05) beneficial effects of ethanol, with treated animals displaying improved motor coordination when compared with untreated animals.

CONCLUSIONS

The present findings suggest that acute ethanol administration after a TBI decreases AQP expression, which may lead to reduced cerebral edema. Ethanol-treated animals additionally showed improved cognitive and motor outcomes compared with untreated animals.

α-MSH: a potential neuroprotective and immunomodulatory agent for the treatment of stroke

Alpha-melanocyte-stimulating hormone (MSH) is a neuropeptide with profound immunomodulatory properties; we evaluated the effects of α-MSH on stroke outcome and its ability to modulate the postischemic immune response. In Lewis rats subjected to 3 hours of middle cerebral artery occlusion (MCAO), plasma concentrations of α-MSH rapidly decreased and returned to baseline over the course of days. Exogenous administration of α-MSH (100 or 500 μg/kg) improved 24 hour outcome in animals subjected to 2 hours MCAO; α-MSH 500 μg/kg also decreased infarct volume at this time point. Both doses of α-MSH were ineffective in improving outcome or decreasing infarct volume in animals subjected to 3 hours MCAO. The splenocyte response to phytohemagglutin in animals treated with α-MSH was attenuated at 24 hours after MCAO. At 1 month after MCAO, treatment with α-MSH 500 μg/kg at the time of stoke was associated with a decrease in TH1 response to myelin basic protein (MBP) in animals subjected to 2 hours MCAO, although treatment was not associated with improved outcome at this time point. Given the early benefits of α-MSH treatment and its effect on immunologic outcome, further studies to evaluate the utility of α-MSH for the treatment of cerebral ischemia are warranted.

Anamnestic recall of stroke-related deficits: an animal model

BACKGROUND AND PURPOSE

Anamnestic recall of stroke-related deficits is a common clinical observation, especially during periods of systemic infection. The pathophysiology of this transient re-emergence of neurological dysfunction is unknown.

METHODS

Male Lewis rats underwent 3 hours middle cerebral artery occlusion and were treated with lipopolysaccharide or saline at the time of reperfusion. The delayed-type hypersensitivity (DTH) response to myelin basic protein was examined 28 days after middle cerebral artery occlusion. Changes in behavioral outcomes were assessed after DTH testing and repeat administration of lipopolysaccharide or saline at 34 days. At the time of euthanasia (36 days), the immunologic response of splenocytes to myelin basic protein, neuron-specific enolase, and proteolipid protein was determined by enzyme-linked immunospot assay and the number of lymphocytes in the brain determined by immunocytochemistry.

RESULTS

Animals treated with lipopolysaccharide at middle cerebral artery occlusion had a greater DTH response to myelin basic protein than animals treated with saline. Among those animals that had fully recovered on a given behavioral test before DTH testing, those treated with lipopolysaccharide at middle cerebral artery occlusion displayed more neurological deterioration after DTH testing and had more CD8(+) lymphocytes within the ischemic core of the brain. Furthermore, the Th1 immune response to brain antigens in the spleen was more robust among those animals that deteriorated after DTH testing and there were more CD4(+) lymphocytes in the penumbral region of animals with a Th1 response to myelin basic protein.

CONCLUSIONS

Our data suggest that an immune response to the brain contributes to the phenomenon of anamnestic recall of stroke-related deficits after an infection. The contribution of the immune response to this phenomenon deserves further investigation.

Sleep deprivation attenuates experimental stroke severity in rats

Indirect epidemiological and experimental evidence suggest that the severity of injury during stroke is influenced by prior sleep history. The aim of our study was to test the effect of acute sleep deprivation on early outcome following experimental stroke. Young male Sprague-Dawley rats (n=20) were subjected to focal cerebral ischemia by reversible right middle cerebral artery occlusion (MCAO) for 90 min. In 10 rats, MCAO was performed just after 6-h of total sleep deprivation (TSD) by "gentle handling", whereas the other rats served as controls. Neurological function during the first week after stroke was monitored using a battery of behavioral tests investigating the asymmetry of sensorimotor deficit (tape removal test and cylinder test), bilateral sensorimotor coordination (rotor-rod and Inclined plane) and memory (T-maze and radial maze). Following MCAO, control rats had impaired behavioral performance in all tests. The largest impairment was noted in the tape test where the tape removal time from the left forelimb (contralateral to MCAO) was increased by approximately 10 fold (p<0.01). In contrast, rats subjected to TSD had complete recovery of sensorimotor performance consistent with a 2.5 fold smaller infarct volume and reduced morphological signs of neuronal injury at day 7 after MCAO. Our data suggest that brief TSD induces a neuroprotective response that limits the severity of a subsequent stroke, similar to rapid ischemic preconditioning.

The quantitative assessment of functional impairment and its correlation to infarct volume in rats with transient middle cerebral artery occlusion

The purpose of this study was to quantitatively assess motor activity and sensory functions and to determine their relationships to infarct severity by measuring infarct volume in rats with transient ischemic stroke. Male Sprague-Dawley rats (11 weeks old, n = 42) were randomly divided into 4 separate groups; a sham operation group, and 1-h, 2-h and 3-h middle cerebral artery occlusion (MCAO) groups. Percent weights borne on paretic hind limbs were measured consecutively for 7 days starting from the day before the induction of ischemia. Fifty percent withdrawal threshold values of forepaws and hindpaws were measured using von-Frey hairs. Infarct volumes in the three ischemic groups, which were significantly different (p < 0.01) from each other, were found to increase in size with ischemic time. The percent weight borne on paretic hind limb in the three MCAO groups were significantly lower than that in the sham group, and this functional deficit remained significant throughout the observational period (p < 0.01). A significant correlation was found between infarct volumes and percent weight borne on paretic hind limbs after ischemia (-0.7 < rho < -0.4, p < 0.05). In contrast the 50% withdrawal threshold values of paretic forepaws and hindpaws in the three ischemic groups were not significantly different from those of the sham controls. Motor test findings, which were used to assess reductions in paretic hind limb weightbearing, were shown to be correlated with infarct volume. The present study shows that this test could be used as a tool to objectively and quantitatively assess functional outcome in MCAO rats.

Cerebral embolic ischemia in rats: correlation of stroke severity and functional deficit as important outcome parameter

The embolic MCA occlusion model in rats is used for recanalisation studies in acute stroke. In addition to the determination of lesion size, the assessment of functional outcome may improve the value of this model. Male Wistar rats were submitted to MCA clot embolism or sham surgery. In order to achieve a larger variety of lesion volume, 2 subgroups (each 7 animals) were subjected to differently sized emboli (30 and 40 mm). Follow-up period was 6 days. Outcome assessment consisted of a test battery including parallel bar crossing, observation of behaviour in an open field and an 8-arm maze and a neurological score with ten different sensorimotor and coordinative items. Animals were perfusion-fixed on day 7 (blinded examination). For both subgroups, there were significant impairments with regard to performance on the Neuro score, parallel bar crossing and maze exploration. Improvement was only partial during the follow-up period. On follow-up day 6, there was still a significant correlation between total infarct volume and functional outcome on the Neuro score (R=0.80, p=0.0006) and the exploration behaviour in the maze (R=0.66, p=0.01). Application of emboli with a length of 40 mm caused more functional impairment and a more extended lesion volume compared with 30 mm. We present outcome tests that provide quantitative and objective tools to test functional impairment in rats following embolic stroke.

Altered MAP kinase phosphorylation and impaired motor coordination in PTPRR deficient mice

The neuronal protein tyrosine phosphatases encoded by mouse gene Ptprr (PTPBR7, PTP-SL, PTPPBSgamma-42 and PTPPBSgamma-37) have been implicated in mitogen-activated protein (MAP) kinase deactivation on the basis of transfection experiments. To determine their physiological role in vivo, we generated mice that lack all PTPRR isoforms. Ptprr-/- mice were viable and fertile, and not different from wildtype littermates regarding general physiology or explorative behaviour. Highest PTPRR protein levels are in cerebellum Purkinje cells, but no overt effects of PTPRR deficiency on brain morphology, Purkinje cell number or dendritic branching were detected. However, MAP kinase phosphorylation levels were significantly altered in the PTPRR-deficient cerebellum and cerebrum homogenates. Most notably, increased phospho-ERK1/2 immunostaining density was observed in the basal portion and axon hillock of Ptprr-/- Purkinje cells. Concomitantly, Ptprr-/- mice displayed ataxia characterized by defects in fine motor coordination and balance skills. Collectively, these results establish the PTPRR proteins as physiological regulators of MAP kinase signalling cascades in neuronal tissue and demonstrate their involvement in cerebellum motor function.

Talampanel improves the functional deficit after transient focal cerebral ischemia in rats. A 30-day follow up study

The neuroprotective effect of talampanel, a negative allosteric modulator of alpha-amino-3-hydroxy-methyl-4-isoxazolyl-propionic acid (AMPA) receptors has been described previously. However, in these studies the histological changes and not the functional consequences of the brain damage were evaluated. The aim of present investigation was to analyze the sensorimotor function after stroke and to test the influence of talampanel (GYKI-53773, LY-300164) by 30-day monitoring in rats. After 1h middle cerebral artery occlusion (MCAO) general 'well-being', neurological status, spontaneous motor activity, rotation, motor coordination, balancing, muscle strength and reaction time were followed for 1 month. Talampanel (6 x 10 mg/kg i.p. given on the day of stroke) improved the motor coordination in rotarod (p < 0.01) and beam walking (p < 0.01) tests, reduced the number of stroke-induced rotations (p < 0.05), shortened the reflex time on the forelimb contralateral to brain ischemia and improved the survival rate comparing with vehicle treated control. After stroke, serious sensorimotor deficits appeared in rats but they showed partial spontaneous recovery after 30 days. Talampanel treatment enhanced the rate of functional improvement without changing the morphology at the end of the experiment. Our results indicate that modulation of AMPA receptors by talampanel can be a promising therapeutic approach to the treatment of stroke.

Extradural compression of the sensorimotor cortex delays the acquisition but not the recalling of a lever-pressing task in Wistar rats

The learning and recalling of a lever-press task (LPT) after brief unilateral extradural compression (EC) of the right sensorimotor cortex was studied in Wistar rats. All rats, regardless of the time-point for EC, were trained to lever press for food from D(day)1 to D6. On D8, the position of the active lever was changed to the right side of the operant box and performance was tested until D14. Total and active lever presses, as well as % errors were used to analyse the performance. Rats submitted to EC 24 h before initiating the LPT schedule (naïve-compressed group) showed delayed task acquisition and impaired performance until D10. No significant impairments were detected by D3 on a beam-walking test, excluding paresis as the cause to the delay. Rats submitted to EC after they learned the LPT (trained-compressed group) showed only mildly impaired post-compression performance with no effects on the recalling of the task. Using a progressive ratio LPT, the maximum number of presses to obtain a food-pellet (breaking point) was significantly reduced 24h after EC suggesting reduced motivation for the task early after brain injury. The delayed acquisition of the LPT in naïve-compressed rats was accompanied by consistent cortical, striatal and thalamic degeneration detected by Fluoro-Jade and anti-glial fibrillary acidic protein (GFAP) staining, whereas the improvement in the performance of this group was accompanied by a reduction of the cortical damage on D10. Recall of the LPT in trained-compressed rats was not altered by EC, suggesting the contribution of compensatory mechanisms.

Effect of testosterone on functional recovery in a castrate male rat stroke model

Both increased and decreased testosterone levels have been reported to correlate with poor outcome after acute ischemic stroke. The present study focused on the role of testosterone during recovery from neurological deficits in a rat focal ischemia model. Castrate male rats were subjected to behavioral tests after 90 min of middle cerebral artery occlusion (MCAO). On day 7 post-MCAO, neurological deficit-matched rats were assigned to a treatment group implanted with subcutaneous testosterone pellets or a control group implanted with sham cholesterol pellets. After 4 weeks post-MCAO, the average infarct volume was not significantly different between the two groups. Rats in the testosterone group demonstrated significantly earlier improvement in neurological deficits and shortened latency of adhesive tape removal compared with the control group as analyzed by Wilcoxon signed ranks test. Walking on parallel bars improved in both groups with a trend towards early recovery observed in the testosterone group. Biased left body swings persisted during the test period in both groups post-MCAO. Serum testosterone was within physiological levels in the treatment group but was not detectable in the control group by radioimmunoassay. GAP-43 and synaptophysin expression did not differ between groups. Less GFAP expression and reactive astrocyte hypertrophy were found around the infarct area in testosterone-treated rats compared with control rats. In conclusion, testosterone replacement post-MCAO accelerated functional recovery in castrate rats, suggesting a potential therapeutic role for testosterone replacement in stroke recovery.

Local saline infusion into ischemic territory induces regional brain cooling and neuroprotection in rats with transient middle cerebral artery occlusion

OBJECTIVE

The neuroprotective effect of hypothermia has long been recognized. Use of hypothermia for stroke therapy, which is currently being induced by whole-body surface cooling, has been limited primarily because of management problems and severe side effects (e.g., pneumonia). The goal of this study was to determine whether local infusion of saline into ischemic territory could induce regional brain cooling and neuroprotection.

METHODS

A novel procedure was used to block the middle cerebral artery of rats for 3 hours with a hollow filament and locally infuse the middle cerebral artery-supplied territory with 6 ml cold saline (20 degrees C) for 10 minutes before reperfusion.

RESULTS

The cold saline infusion rapidly and significantly reduced temperature in cerebral cortex from 37.2 +/- 0.1 to 33.4 +/- 0.4 degrees C and in striatum from 37.5 +/- 0.2 to 33.9 +/- 0.4 degrees C. The significant hypothermia remained for up to 60 minutes after reperfusion. Significant (P < 0.01) reductions in infarct volume (approximately 90%) were evident after 48 hours of reperfusion. In ischemic rats that received the same amount of cold saline systemically through a femoral artery, a mild hypothermia was induced only in the cerebral cortex (35.3 +/- 0.2 degrees C) and returned to normal within 5 minutes. No significant reductions in infarct volume were observed in this group or in the ischemic group with local warm saline infusion or without infusion. Furthermore, brain-cooling infusion significantly (P < 0.01) improved motor behavior in ischemic rats after 14 days of reperfusion. This improvement continued for up to 28 days after reperfusion.

CONCLUSION

Local prereperfusion infusion effectively induced hypothermia and ameliorated brain injury from stroke. Clinically, this procedure could be used in acute stroke treatment, possibly in combination with intra-arterial thrombolysis or mechanical disruption of clot by means of a microcatheter.

Exercise pre-conditioning reduces brain damage in ischemic rats that may be associated with regional angiogenesis and cellular overexpression of neurotrophin

There is increasing evidence that physical activity is associated with a decreased stroke risk. The purpose of this study was to determine if exercise could also reduce brain damage in rats subjected to transient middle cerebral artery (MCA) occlusion, and if the reduced brain injury is associated with angiogenesis as well as cellular expression of the nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in regions supplied by the MCA. Adult male Sprague Dawley rats (n=36) exercised 30 min each day for 3 weeks on a treadmill on which repetitive locomotor movement was required. Then, stroke was induced by a 2-h MCA occlusion using an intraluminal filament, followed by 48 h of reperfusion. In addition to the two exercised groups of animals with or without MCA occlusion, there were two other groups of animals, with or without MCA occlusion, housed for the same duration and used as non-exercised controls. Brain damage in ischemic rats was evaluated by neurologic deficits and infarct volume. Exercise preconditioned and non-exercised brains were processed for immunocytochemistry to quantify the number of microvessels or NGF- and BDNF-labeled cells. Pre-ischemic motor activity significantly (P<0.01) reduced neurologic deficits and infarct volume in the frontoparietal cortex and dorsolateral striatum. Cellular expressions of NGF and BDNF were significantly (P<0.01) increased in cortex (neuron) and striatum (glia) of rats under the exercise condition. Significant (P<0.01) increases in microvessel density were found in striatum. Physical activity reduced stroke damage. The reduced brain damage may be attributable to angiogenesis and neurotrophin overexpression in brain regions supplied by the MCA following exercise.

Chronic behavioral testing after focal ischemia in the mouse: functional recovery and the effects of gender

Several useful behavioral tests exist for measuring behavioral recovery after ischemia in higher-order animals and rats. With the increasing use of mice in focal stroke research, simple, reliable, and reproducible behavioral testing has become a priority. As neuroprotective agents are tested, long-term outcome must be assessed, especially in studies focused on neuronal plasticity and regeneration after ischemia. Our laboratory and others have previously shown that estrogen (E2) is neuroprotective in rodent stroke paradigms. We examined a battery of behavioral tests in male and female mice subjected to 90 min of middle cerebral artery occlusion (MCAO) to determine the most sensitive tests for detecting sensorimotor dysfunction after stroke, and to determine the functional significance of E2-mediated neuroprotection. Only two tests, the corner test and the cylinder test, were able to differentiate between groups (sham and stroke) after several days of repeated testing. The cylinder test was sensitive to the neuroprotective/neurorestorative effects of E2, but 2 weeks after stroke, the cylinder test was unable to distinguish between sham and stroke animals treated with E2. In contrast, the corner test was able to differentiate stroke and sham animals even 6 weeks after stroke, but did not distinguish animals treated with E2 vs. vehicle. These tests provide a simple, rapid, reliable assessment of sensorimotor dysfunction in the mouse after focal ischemia. Hormonal status influences speed of recovery on cylinder testing in animals of both genders. This suggests that a short battery of tests including the neurological score, cylinder, and corner test may be adequate to rapidly and repeatedly assess sensorimotor dysfunction in mice of both genders.

Motor balance and coordination training enhances functional outcome in rat with transient middle cerebral artery occlusion

The goal of this study was to determine if relatively complex motor training on Rota-rod involving balance and coordination plays an essential role in improving motor function in ischemic rats, as compared with simple locomotor exercise on treadmill. Adult male Sprague-Dawley rats with (n=40) or without (n=40) ischemia were trained under each of three conditions: (1) motor balance and coordination training on Rota-rod; (2) simple exercise on treadmill; and (3) non-trained controls. Motor function was evaluated by a series of tests (foot fault placing, parallel bar crossing, rope and ladder climbing) before and at 14 or 28 days after training procedures in both ischemic and normal animals. Infarct volume in ischemic animals was determined with Nissl staining. Compared with both treadmill exercised and non-trained animals, Rota-rod-trained animals with or without ischemia significantly (P<0.01) improved motor performance of all tasks except for foot fault placing after 14 days of training, with normal rats having better performance. Animals trained for up to 28 days on the treadmill did not show significantly improved function. With regard to foot fault placing task, performance on foot placing was improved in ischemic rats across the three measurements at 0, 14 and 28 days regardless of training condition, while the normal group reached their best performance at the beginning of measurement. No significant differences in infarct volume were found in rats trained either with Rota-rod (47+/-4%; mean+/-S.E.), treadmill (45+/-5%) or non-exercised control (45+/-3%). In addition, no obvious difference could be detected in the location of the damage which included the dorso-lateral portion of the neostriatum and the frontoparietal cortex, the main regions supplied by the middle cerebral artery. The data suggest that complex motor training rather than simple exercise effectively improves functional outcome.

Neural stem cell transplantation in cold lesion: a novel approach for the investigation of brain trauma and repair

We developed a new neural transplantation protocol for the investigation of the repair of brain trauma. Cortical lesion was induced by touching a cold (-60 degrees C) metal stamp to the dura over the forelimb motor cortex of adult rats. The procedure caused a localized lesion and the animals developed a significant motor deficit, which was monitored throughout the protocol. Six days later the animals received embryonic neural stem cells in the penumbra of the lesion. The donor cells were freshly isolated from E14 rat embryos, had a high viability, and expressed the stem cell marker nestin. A further 6 days later the survival and differentiation of the grafted cells were investigated by immunohistochemistry. The majority of the surviving grafted cells were found in the lesion and they did not express lineage-specific markers. Only 10% of all surviving transplanted cells were located in the penumbra. These cells had an astrocytic phenotype and expressed glial fibrillary acidic protein. A few cells expressed neural or oligodendrocytic markers. In conclusion, we established a novel neural transplantation protocol, which focuses on cortical brain trauma. The model is a combination of surgical, neurological and histological approaches, all adapted to each other to make a reliable and reproducible experimental model.

Synaptic plasticity in thalamic nuclei enhanced by motor skill training in rat with transient middle cerebral artery occlusion

The goal of this study was to determine if synaptic plasticity in the thalamus of rats subjected to stroke could be altered by motor training. Transient occlusion of right middle cerebral artery in adult female Sprague-Dawley rats (n = 35) was induced with an intraluminal filament followed by three training conditions, 1. motor skill training on Rota-rod requiring balance and coordination skills, 2. simple exercise on treadmill, and 3. nontrained controls. Synaptic plasticity in brain was evaluated by synapotophysin immunocytochemistry at 14 or 28 days after training procedures. Infarct volume was determined in Nissl stained sections. Both at 14 and 28 days after Rota-rod training, intense synaptophysin immunoreactivity was present in the right but not the left mediodorsal and ventromedial nuclei of thalamus of ischemic rats. In treadmill-trained animals, however, similarly intense synaptic plasticity in these two thalamic nuclei was seen only at 28 days. Immunostaining was found also in other brain regions adjacent to or remote from infarct site. The data suggest that motor training, particularly motor skill training involving balance and coordination, facilitates a uniquely lateralized synaptogenesis in the thalamus.

Functional improvement after motor training is correlated with synaptic plasticity in rat thalamus

The goals of this study were to determine whether functional outcome after motor training in rats was linked to synaptic plasticity in thalamus, and whether the Rota-rod apparatus, widely used to test motor function, could be used as an easy and quantitative motor skill training procedure. Adult female Sprague-Dawley rats (n = 39) were evaluated under three training conditions: 1. Movement requiring balance and coordination skills on Rota-rod; 2. simple exercise on treadmill; 3. nontrained controls. Motor function was evaluated by a series of motor tests (foot fault placing, parallel bar crossing, rope and ladder climbing) before and 14 or 28 days after training procedure. Synaptic strength in brain was assessed by synaptophysin immunocytochemistry. After 14 days of training, Rota-rod-trained animals significantly (p < 0.01) improved motor performance, compared to treadmill and nontrained animals. Animals with up to 28 days of simple exercises on the treadmill did not show a significantly improved performance on most motor tasks, except for an improvement in foot fault placing. Intensive synaptophysin immunoreactivity was present in the right but not the left mediodorsal and ventromedial nuclei of thalamus in Rota-rod-trained rats at 14 and 28 days, and in treadmill-trained rats at 28 days. The data suggested that functional outcome is effectively improved by motor skill training rather than by simple exercises, and this may be related, at least partially, to uniquely lateralized synaptogenesis in the thalamus. Both Rota-rod and treadmill could be quantitatively used in rats for motor training of different complexity.