Satoshi Kuramoto

Exercise exerts neuroprotective effects on Parkinson's disease model of rats

Recent studies demonstrate that rehabilitation ameliorates physical and cognitive impairments of patients with stroke, spinal cord injury, and other neurological diseases and that rehabilitation also has potencies to modulate brain plasticity. Here we examined the effects of compulsive exercise on Parkinsons disease model of rats. Before 6-hydroxydopamine (6-OHDA, 20 microg) lesion into the right striatum of female SD rats, bromodeoxyuridine (BrdU) was injected to label the proliferating cells. Subsequently, at 24 h after the lesion, the rats were forced to run on the treadmill (5 days/week, 30 min/day, 11 m/min). As behavioral evaluations, cylinder test was performed at 1, 2, 3, and 4 weeks and amphetamine-induced rotational test was performed at 2 and 4 weeks with consequent euthanasia for immunohistochemical investigations. The exercise group showed better behavioral recovery in cylinder test and significant decrease in the number of amphetamine-induced rotations, compared to the non-exercise group. Correspondingly, significant preservation of tyrosine hydroxylase (TH)-positive fibers in the striatum and TH-positive neurons in the substantia nigra pars compacta (SNc) was demonstrated, compared to the non-exercise group. Additionally, the number of migrated BrdU- and Doublecortin-positive cells toward the lesioned striatum was increased in the exercise group. Furthermore, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor increased in the striatum by exercise. The results suggest that exercise exerts neuroprotective effects or enhances the neuronal differentiation in Parkinsons disease model of rats with subsequent improvement in deteriorated motor function.

Intrapallidal metabotropic glutamate receptor activation in a rat model of Parkinson's disease: Behavioral and histological analyses

Metabotropic glutamate receptors (mGluRs) have been recently implicated as robust therapeutic targets for Parkinsons disease (PD). Here, we explored how activation of mGluRs in globus pallidus (GP) affected the amphetamine-induced rotational behavior in the unilateral 6-hydroxydopamine (6-OHDA) lesion rat model of PD. The amphetamine-induced rotations were completely suppressed by the ipsilateral intrapallidal injection of the non-selective mGluR agonist, 1-aminocyclopentane-1S,3R-dicarboxylic acid (ACPD) and the selective group I mGluR agonist, (R,S)-3,5-dihydroxyphenylglycine (DHPG), but not the selective group III mGluR agonist, l-2-amino-4-phosphonobutyric acid (l-AP4). The suppressive effects were detected at 2, 4, 6, 8, and 12 h after ACPD injection, but returned to the control level at 24 h. A remarkable c-fos expression was found in the lesioned side of GP, subthalamic nucleus (STN), and substantia nigra pars reticulata (SNr) of rats that received the ACPD or DHPG injection, compared to rats treated with L-AP-4 or phosphate buffer-injection. The results indicate that the blockade of amphetamine-induced rotations might be at least partially mediated by group I mGluR activation. This study advances the use of selective group I mGluRs directed toward the GP for PD treatment.

Striatal stimulation nurtures endogenous neurogenesis and angiogenesis in chronic-phase ischemic stroke rats.

Deep brain stimulation (DBS) is used to treat a variety of neurological disorders including Parkinsons disease. In this study, we explored the effects of striatal stimulation (SS) in a rat model of chronic-phase ischemic stroke. The stimulation electrode was implanted into the ischemic penumbra at 1 month after middle cerebral artery occlusion (MCAO) and thereafter continuously delivered SS over a period of 1 week. Rats were evaluated behaviorally coupled with neuroradiological assessment of the infarct volumes using magnetic resonance imaging (MRI) at pre- and post-SS. The rats with SS showed significant behavioral recovery in the spontaneous activity and limb placement test compared to those without SS. MRI visualized that SS also significantly reduced the infarct volumes compared to that at pre-SS or without SS. Immunohistochemical analyses revealed a robust neurogenic response in rats that received SS characterized by a stream of proliferating cells from the subventricular zone migrating to and subsequently differentiating into neurons in the ischemic penumbra, which exhibited a significant GDNF upregulation. In tandem with this SS-mediated neurogenesis, enhanced angiogenesis was also recognized as revealed by a significant increase in VEGF levels in the penumbra. These results provide evidence that SS affords neurorestoration at the chronic phase of stroke by stimulating endogenous neurogenesis and angiogenesis.

BDNF-secreting capsule exerts neuroprotective effects on epilepsy model of rats

Brain-derived neurotrophic factor (BDNF) is a well neurotrophic factor with neuroprotective potentials for various diseases in the central nervous system. However several previous studies demonstrated that BDNF might deteriorate symptoms for epilepsy model of animals by progression of abnormal neurogenesis. We hypothesized that continuous administration of BDNF at low dose might be more effective for epilepsy model of animals because high dose of BDNF was used in many studies. BDNF-secreting cells were genetically made and encapsulated for transplantation. Rats receiving BDNF capsule showed significant amelioration of seizure stage and reduction of the number of abnormal spikes at 7 days after kainic acid administration, compared to those of control group. The number of BrdU and BrdU/doublecortin positive cells in the hippocampus of BDNF group significantly increased, compared to that of control group. NeuN positive cells in the CA1 and CA3 of BDNF group were significantly preserved, compared to control group. In conclusion, low dose administration using encapsulated BDNF-secreting cells exerted neuroprotective effects with enhanced neurogenesis on epilepsy model of rats. These results might suggest the importance of the dose and administrative way of this neurotrophic factor to the epilepsy model of animals.

Erythropoietin exerts anti-epileptic effects with the suppression of aberrant new cell formation in the dentate gyrus and upregulation of neuropeptide Y in seizure model of rats

We explored the effects of exogenous and endogenous erythropoietin (EPO) in a seizure model of rat. Adult male Fischer 344 rats received continuous intraventricular infusion of EPO dissolved in saline containing 1mg/ml of rat serum albumin, anti-EPO antibody, saline containing 1mg/ml of rat serum albumin or combined EPO and neuropeptide Y (NPY) Y2-receptor antagonist. Animals were behaviorally evaluated for seizure development over 6h after kainic acid injection followed by immunohistochemical assays. Mortality rate, seizure severity, apoptotic cell death and abnormal cell proliferation in the hippocampus of EPO-treated epileptic rats were significantly attenuated, compared to control rats. Anti-EPO antibody in non-EPO-treated animals worsened seizures and CA1 neuronal cell death, while NPY Y2-receptor antagonist cancelled the therapeutic effects of exogenous EPO. Both exogenous and endogenous EPO might modulate seizure severity and protect the hippocampal neurons in epileptic rats, via novel mechanistic pathways involving blockade of epileptogenic cell formation coupled with NPY receptor modulation in the hippocampus.

Regenerative Medicine for Epilepsy: From Basic Research to Clinical Application

Epilepsy is a chronic neurological disorder, which presents with various forms of seizures. Traditional treatments, including medication using antiepileptic drugs, remain the treatment of choice for epilepsy. Recent development in surgical techniques and approaches has improved treatment outcomes. However, several epileptic patients still suffer from intractable seizures despite the advent of the multimodality of therapies. In this article, we initially provide an overview of clinical presentation of epilepsy then describe clinically relevant animal models of epilepsy. Subsequently, we discuss the concepts of regenerative medicine including cell therapy, neuroprotective agents, and electrical stimulation, which are reviewed within the context of our data.

Injection of muscimol, a GABAa agonist into the anterior thalamic nucleus, suppresses hippocampal neurogenesis in amygdala-kindled rats

Abstract The relationship between neurogenesis and epilepsy remains to be solved so far, although aberrant electric circuit recognized in epilepsy might be involved in neurogenesis. In this study, neurogenesis and the proliferation of astrocytes in the subgranular zone of the hippocampus were explored using unilateral amygdala-kindled rats with or without muscimol, a gamma-aminobutyric acid a (GABAa) agonist injection into the bilateral anterior thalamic nuclei (AN). Muscimol injection significantly ameliorated the behavioral scores of epilepsy without any significant alteration on the electroencephalography recorded at the stimulated basolateral amygdala, thus suggesting that muscimol injection might affect the secondary generalization, but not the initial discharge itself. The number of bromodeoxyuridine (BrdU), BrdU/doublecortin and BrdU/glial fibrillary acidic protein-positive cells in the subgranular zone of kindled animals increased markedly. Muscimol injection significantly suppressed neurogenesis, but not the proliferation of astrocyte, in the subgranular zone of the non-stimulated side, probably through the suppression of secondary generalization via AN. The results might indicate the underlying relationships between neurogenesis and epilepsy, that epileptic propagation in unilateral amygdala-kindled rats might go through AN into the contralateral side with subsequent neurogenesis, although further studies need to clarify the hypothesis.

Reliability of behavioral analyses in a partial lesion rat model of Parkinson's disease in relation to nigrostriatal dopaminergic depletion

Zebra fish is a common vertebrate model for study of neurogenesis and neurodevelopment. Recently, zebra fish is also employed as model to study neurological disorders including neurodegenerative diseases and drug of abuse. In the present study, constructs were produced containing the promoter of tyrosine hydroxylase (TH; a key synthetic enzyme for catecholamines), and green fluorescence protein (GFP). The constructs were micro-injected into the yolk sac of zebra fish embryos during the one-cell stage. At the 7-day post transfection, GFP was expressed in retinal inner nuclear layer of zebra fish. From 15-day post transfection, posterior tuberculum region and diencephalic catecholaminergic cluster of zebra fish also expressed GFP. The present results were consistent to the TH immunolabeling in the zebra fish embryos during he same developmental stages. The present results demonstrate that TH-GFP transgenic zebra fish can provide endogenous expression of fluorescence marker in catecholaminergic neurons in the fish and are good models for studying neurological disorders relating to catecholamines in the nervous system.

Erythropoietin prevents the epileptogenesis and generalization in the epilepsy model rats

Previous study demonstrated that low power laser irradiation can increase the threshold of electrically induced paroxysmal discharge (PADT) in rabbit hippocampus CA1. The present experiment was designed to reveal effects of electrical coagulation procedure. Using 14 adult rabbits, we measured PADTs elicited by stimulation of 1-ms biphasic pulses of 50 Hz for 1 s before and after electrical coagulation. It was made by direct current of 0.2 (case A), 0.4 (B), 0.6 (C), and 0.8 mA (D) for 2 min. Damaged or infarcted area was measured on the histological sections. Each PADT magnitude to control was 2.3 ± 0.3 (case A: n = 3), 1.7 ± 0.1 (case B: n = 3), 1.7 ± 0.4 (case C: n = 3), and 1.5 ± 0.1 times (case D: n = 2), whereas each diameter of damaged area was 1.7 ± 0.5 (A), 2.1 ± 0.4 (B), 1.7 ± 0.3 (C), and 2.0 ± 0.6 mm (D), respectively. A negative correlation between them was obtained (R = −0.6068). In comparison with laser effects, electrical coagulation produced smaller PADT increment and lager damage, which showed a disadvantage to the laser irradiation.

Continuous deep brain stimulation has a regenerative effect on the ischemic rat model in the chronic stage

Although the perceptive discrimination between itching and pain is clear for us, it is still unclear how our brains produce these different sensations. Thus, we investigated the neural substrates of perceptual differences between itching and pain by fMRI. The anterior cingulate cortex, the anterior insula, the basal ganglia and the pre-supplementary motor area were commonly activated by itching and pain. Neural activity in the posterior cingulate cortex (PCC) and the posterior insula associated with itching was significantly higher than that associated with pain and significantly proportional to itching sensation. Pain, but not itching, induced an activation of the thalamus for several minutes, and neural activity of this brain region significantly correlated to pain sensation. These differences in brain activity would be responsible for the perceptual difference between itching and pain.