Grid Walk Test Research Articles

Cholinergic Receptor Alterations in the Brain Stem of Spinal Cord Injured Rats

Cholinergic receptors in upper motor neurons of brain stem control locomotion and coordination. Present study unravels cholinergic alterations in brain stem during spinal cord injury to understand signalling pathway changes which may be associated with spinal cord injury mediated motor deficits. We evaluated cholinergic function in brain stem by studying the expression of choline acetyl transferase and acetylcholine esterase. We quantified metabotropic muscarinic cholinergic receptors by receptor assays for total muscarinic, muscarinic M1 and M3 receptor subunits, gene expression studies using Real Time PCR and confocal imaging using FITC tagged secondary antibodies. The gene expression of ionotropic nicotinic cholinergic receptors and confocal imaging were also studied. The results from our study showed metabolic disturbance in cholinergic pathway as choline acetyl transferase is down regulated and acetylcholine esterase is up regulated in spinal cord injury group. The significant decrease in muscarinic receptors showed by decreased receptor number along with down regulated gene expression and confocal imaging accounts for dysfunction of metabotropic acetylcholine receptors in spinal cord injury group. Ionotropic acetylcholine receptor alterations were evident from the decreased gene expression of alpha 7 nicotinic acetylcholine receptors and confocal imaging. The motor coordination was analysed by Grid walk test which showed an increased foot slips in spinal cord injured rats. The significant reduction in brain stem cholinergic function might have intensified the motor dysfunction and locomotor disabilities.

Extensive cell migration, axon regeneration, and improved function with polysialic acid‐modified Schwann cells after spinal cord injury

Schwann cell (SC) implantation after spinal cord injury (SCI) promotes axonal regeneration, remyelination repair, and functional recovery. Reparative efficacy, however, may be limited because of the inability of SCs to migrate outward from the lesion-implant site. Altering SC cell surface properties by overexpressing polysialic acid (PSA) has been shown to promote SC migration. In this study, a SCI contusion model was used to evaluate the migration, supraspinal axon growth support, and functional recovery associated with polysialyltransferase (PST)-overexpressing SCs [PST-green fluorescent protein (GFP) SCs] or controls (GFP SCs). Compared with GFP SCs, which remained confined to the injection site at the injury center, PST-GFP SCs migrated across the lesion:host cord interface for distances of up to 4.4 mm within adjacent host tissue. In addition, with PST-GFP SCs, there was extensive serotonergic and corticospinal axon in-growth within the implants that was limited in the GFP SC controls. The enhanced migration of PST-GFP SCs was accompanied by significant growth of these axons caudal to lesion. Animals receiving PST-GFP SCs exhibited improved functional outcome, both in the open-field and on the gridwalk test, beyond the modest improvements provided by GFP SC controls. This study for the first time demonstrates that a lack of migration by SCs may hinder their reparative benefits and that cell surface overexpression of PSA enhances the ability of implanted SCs to associate with and support the growth of corticospinal axons. These results provide further promise that PSA-modified SCs will be a potent reparative approach for SCI. © 2012 Wiley Periodicals, Inc.

The grid-walking test: assessment of sensorimotor deficits after moderate or severe dopamine depletion by 6-hydroxydopamine lesions in the dorsal striatum and medial forebrain bundle

The present study aims to evaluate the applicability of the grid-walking test in rats with moderate or severe dopamine-depletion incurred by unilateral nigro-striatal 6-hydroxydopamine (6-OHDA) lesions. Striatum samples were analyzed by high pressure liquid chromatography coupled to electrochemical detection (HPLC-EC) after behavioral testing. In Experiment 1, 2 weeks after the injection of 6-OHDA into the medial forebrain bundle, adult Wistar rats were divided into an l-3,4-dihydroxyphenylalanine (l-dopa) and a vehicle treatment group and their behaviors on the grid were compared. The severely lesioned animals (mean dopamine depletion of 92%) did not exhibit behavioral asymmetry in the number of contralateral foot-slips. However, l-dopa administration selectively reduced the number of foot-slips of the contralateral forelimb when compared with the vehicle group. In Experiment 2, 6-OHDA was injected into the dorsal striatum and foot-slips on the grid were analyzed 4, 9 and 13 days following the lesion. The rats with moderate dopamine-depletion (mean depletion of 54%) exhibited more contralateral forelimb-slips on all testing days. Compared with naive rats, hemiparkinsonian rats also showed more forelimb-slips. These results suggest that the grid-walking test should be a powerful and sensitive behavioral assay for sensory-motor deficits in rat models of nigro-striatal dopamine lesions.

Decreased cholinergic receptor expression in the striatum: motor function deficit in hypoglycemic and diabetic rats.

Hypoglycemic brain injury is a common and serious complication of insulin therapy associated with diabetes. This study evaluated the effect of insulin-induced hypoglycemia and STZ-induced diabetes on striatal cholinergic receptors and enzyme expression and on motor function. Cholinergic enzymes: AChE and ChAT gene expression, radioreceptor binding assay and immunohistochemistry of muscarinic M1, M3 receptors and α7nAChR were carried out. Motor performance on grid walk test was analysed. AChE and ChAT expression significantly downregulated in hypoglycemic and diabetic rats. Total muscarinic and Muscarinic M3 receptor binding decreased in hypoglycemic rats compared to diabetic rats whereas muscarinic M1 receptor binding increased in hypoglycemic rats compared to diabetic rats. Real-time PCR analysis and confocal imaging of muscarinic M1, M3 receptors confirmed the changes in muscarinic receptor binding in hypoglycemic and diabetic rats. In hypoglycemic rats, α7nAChR expression significantly up regulated compared to diabetic rats. Grid walk test demonstrated the impairment in motor function and coordination in hypoglycemic and hyperglycemic rats. Neurochemical changes along with the behavioral data implicate a role for impaired striatal cholinergic receptor function inducing motor function deficit induced by hypo and hyperglycemia. Hypoglycemia exacerbated the neurobehavioral deficit in diabetes which has clinical significance in the treatment of diabetes.

C-Jun N-terminal kinase induces axonal degeneration and limits motor recovery after spinal cord injury in mice

C-Jun N-terminal kinase (JNK) mediates neuronal death in response to stress and injury in the CNS and peripheral nervous system. Here, we show that JNK also regulates retrograde axonal degeneration (axonal dieback) after spinal cord injury (SCI) in mice. Activated phospho-JNK was highly expressed in damaged corticospinal tract (CST) axons after thoracic SCI by hemisection. Local administration of SP600125, a JNK inhibitor, prevented accumulation of amyloid-β precursor protein and retraction of the severed CST axons as well as preserved the axonal arbors rostral to the injury site. The treatment with SP600125 also improved functional recovery of the hindlimbs, assessed by Basso mouse scale open-field scores and the grid-walking test. In Jnk1 −/− and Jnk3 −/− mice, we observed prevention of axonal degeneration and enhancement of motor recovery after SCI. These results indicate that both JNK1 and JNK3 induce axonal degeneration and limit motor recovery after SCI. Thus, a JNK inhibitor may be a suitable therapeutic agent for SCI.

Neural regrowth induced by PLGA nerve conduits and neurotrophin‐3 in rats with complete spinal cord transection

Biomaterials and neurotrophic factors represent two promising strategies for spinal cord injury repair. In this study, a combinatorial approach combining the PLGA nerve conduits and the recombinant human neurotrophin-3 (rhNT3) was utilized in a spinal cord injury animal model. After complete transection of the thoracic cord in rats, rhNT3 was administered as a single dose to the host cord caudal to a 2-mm conduit. Axonal regrowth was enhanced, as indicated by immunostaining and neurofilament-positive area measurement. Neural regrowth was further demonstrated via the retrograde tracing across the lesion. The animals implanted with the PLGA scaffold and rhNT3 exhibited significantly improved performance in BBB rating scale and grid walk tests. These observations suggest that PLGA nerve conduits combined with exogenous NT3 may serve as an alternative therapeutic approach for spinal cord injury repair.

Axonal remodeling for motor recovery after traumatic brain injury requires downregulation of γ-aminobutyric acid signaling

Remodeling of the remnant neuronal network after brain injury possibly mediates spontaneous functional recovery; however, the mechanisms inducing axonal remodeling during spontaneous recovery remain unclear. Here, we show that altered γ-aminobutyric acid (GABA) signaling is crucial for axonal remodeling of the contralesional cortex after traumatic brain injury. After injury to the sensorimotor cortex in mice, we found a significant decrease in the expression of GABAAR-α1 subunits in the intact sensorimotor cortex for 2 weeks. Motor functions, assessed by grid walk and cylinder tests, spontaneously improved in 4 weeks after the injury to the sensorimotor cortex. With motor recovery, corticospinal tract (CST) axons from the contralesional cortex sprouted into the denervated side of the cervical spinal cord at 2 and 4 weeks after the injury. To determine the functional implications of the changes in the expression of GABAAR-α1 subunits, we infused muscimol, a GABA R agonist, into the contralesional cortex for a week after the injury. Compared with the vehicle-treated mice, we noted significantly inhibited recovery in the muscimol-treated mice. Further, muscimol infusion greatly suppressed the axonal sprouting into the denervated side of the cervical spinal cord. In conclusion, recovery of motor function and axonal remodeling of the CST following cortical injury requires suppressed GABAAR subunit expression and decreased GABAergic signaling.

Hypoglycemia induced behavioural deficit and decreased GABA receptor, CREB expression in the cerebellum of streptozoticin induced diabetic rats

Intensive glycemic control during diabetes is associated with an increased incidence of hypoglycemia, which is the major barrier in blood glucose homeostasis during diabetes therapy. The CNS neurotransmitters play an important role in the regulation of glucose homeostasis. In the present study, we showed the effects of hypoglycemia in diabetic and non- diabetic rats on motor functions and alterations of GABA receptor and CREB expression in the cerebellum. Cerebellar dysfunction is associated with seizure generation, motor deficits and memory impairment. Scatchard analysis of [ 3H]GABA binding in the cerebellum of diabetic hypoglycemic and control hypoglycemic rats showed significant ( P < 0.01) decrease in B max and K d compared to diabetic and control rats. Real-time PCR amplification of GABA receptor subunit GABA Aα1 and GAD showed significant ( P < 0.001) down-regulation in the cerebellum of hypoglycemic rats compared to diabetic and control rats. Confocal imaging study confirmed the decreased GABA receptors in hypoglycemic rats. CREB mRNA expression was down-regulated during recurrent hypoglycemia. Both diabetic and non-diabetic hypoglycemic rats showed impaired performance in grid walk test compared to diabetic and control. Impaired GABA receptor and CREB expression along with motor function deficit were more prominent in hypoglycemic rats than hyperglycemic which showed that hypoglycemia is causing more neuronal damage at molecular level. These molecular changes observed during hypo/hyperglycemia contribute to motor and learning deficits which has clinical significance in diabetes treatment.

Linear Ordered Collagen Scaffolds Loaded with Collagen-Binding Neurotrophin-3 Promote Axonal Regeneration and Partial Functional Recovery after Complete Spinal Cord Transection

Neurotrophin-3 (NT3) is an important neurotrophic factor for spinal cord injury (SCI) repair. However, constant exchange of cerebrospinal fluid often decreases the effective dosage of NT3 at the targeted injury site. In the present study, a recombinant collagen-binding NT3 (CBD-NT3), consisting of a collagen-binding domain (CBD) and native NT3, was constructed. Linear rat-tail collagen (LRTC) was used as a physical carrier for CBD-NT3 to construct a LRTC/C3 system. The collagen-binding ability of CBD-NT3 was verified, and the bioactivity of CBD-NT3 was assayed with neurite outgrowth of dorsal root ganglia (DRG) explants and DRG cells in vitro. After complete spinal cord transection in rats, LRTC/CBD-NT3 or the LRTC/NT3 system was transplanted into the injury site. Hindlimb locomotion recovery was closely observed using the Basso-Beattie-Bresnahan (BBB) locomotor rating scale and the grid walk test. Significant improvement was observed in the LRTC/CBD-NT3 group. The results of regenerating nerve fiber and anterograde tracing of biotinylated dextran amine (BDA)-labeled corticospinal tract (CST) fibers demonstrated axonal regeneration of LRTC/CBD-NT3 in the injured spinal cord. Serotonin fiber regrowth also illustrated the effectiveness of LRTC/CBD-NT3. Thus, collagen-binding NT3 with LRTC may provide an effective method for treating SCI.

Cerebrolysin reduces blood‐cerebrospinal fluid barrier permeability change, brain pathology, and functional deficits following traumatic brain injury in the rat

Traumatic brain injuries (TBIs) induce profound breakdown of the blood-brain and blood-cerebrospinal fluid barriers (BCSFB), brain pathology/edema, and sensory-motor disturbances. Because neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and glial cell-derived neurotrophic factor (GDNF), are neuroprotective in models of brain and spinal cord injuries, we hypothesized that a combination of neurotrophic factors would enhance neuroprotective efficacy. In the present investigation, we examined the effects of Cerebrolysin, a mixture of different neurotrophic factors (Ebewe Neuro Pharma, Austria) on the brain pathology and functional outcome in a rat model of TBI. TBI was produced under Equithesin (3 mL/kg, i.p.) anesthesia by making a longitudinal incision into the right parietal cerebral cortex. Untreated injured rats developed profound disruption of the blood-brain barrier (BBB) to proteins, edema/cell injury, and marked sensory-motor dysfunctions on rota-rod and grid-walking tests at 5 h TBI. Intracerebroventricular administration of Cerebrolysin (10 or 30 microL) either 5 min or 1 h after TBI significantly reduced leakage of Evans blue and radioiodine tracers across the BBB and BCSFB, and attenuated brain edema formation/neuronal damage in the cortex as well as underlying subcortical regions. Cerebrolysin-treated animals also had improved sensory-motor functions. However, administration of Cerebrolysin 2 h after TBI did not affect these parameters significantly. These observations in TBI demonstrate that early intervention with Cerebrolysin reduces BBB and BCSFB permeability changes, attenuates brain pathology and brain edema, and mitigates functional deficits. Taken together, our observations suggest that Cerebrolysin has potential therapeutic value in TBI.

백서의 척수손상 후 중강도 저체온법과 수중운동이 운동기능에 미치는 영향

본 연구는 백서의 척수손상 후 중강도 저체온법과 수중운동이 운동기능에 미치는 영향을 알아보기 위해 신경학적 운동행동 검사와 면역조직화학적 평가를 실시하였다. 실험대상은 척수손상 유발 후 아무런 처치를 하지 않은 대조군(n=12), 척수손상 유발 직후 저체온법을 적용한 실험군 I(n=12), 척수손상 유발 후 수중운동을 실시한 실험군 II(n=12), 척수손상 유발 직후 저체온법을 적용한 후 수중운동을 실시한 실험군 III(n=12)으로 나누었다. 모든 실험군은 3일, 7일, 14일, 21일에 신경학적 운동행동 검사를 실시하였고, 3일, 7일, 21일에는 면역조직화학적 평가를 실시하였다. BBB 척도에서 14일에 대조군과 비교하여 실험군 II와 III이 통계학적으로 매우 유의한 차이를 보였으며(p<.001), 격자걷기 검사에서 대조군과 비교하여 실험군 III이 통학적으로 유의한 차이를 보였다(p<.05). 면역조직화학적 평가에서, BDNF의 발현량은 실험군 III에서 가장 많이 관찰되었다. 이와 같은 결과를 통해 중강도 저체온법과 수중운동이 척수손상 후 운동기능에 긍정적인 효과가 있음을 알 수 있었다. This study was designed to investigate the effects of mild hypothermia and Aquatic exercise on function Activity after experimental Spinal Cord Injury(SCI) rats. Experimental groups were divided into the control group (non-treatment after SCI induction), group I(hypothermia after SCI induction), group II(exercise after SCI induction), group III(hypothermia and exercise after SCI induction). After operation, rats were examined neurological motor behavior test at 3, 7, 14, 21 days and Immunohistochemical assessment at 3, 7, 21 days.Each other 14 days were a statistically significant difference between control group and group II, III(p<.001) in BBB scale, between control group and group III(p<.05) in grid walk test. In mmunohistochemical assessment, there was appeared highest express in group III. Based on these results, mild hypothermia and exercise was effected functional Activity after SCI.

Predictable ventricular shift after focal cerebral ischaemia in rats: practical considerations for intraventricular therapeutic interventions

Intracerebroventricular (ICV) route of administration is a useful experimental method to study the effects of chemicals or cellular grafts in the ventricular compartment of the brain after focal ischaemia. However, the induced oedema may cause structural dislocating phenomena and render a stereotaxic ICV invasion difficult and practically unavailable especially during the acute post-ischaemia phase. The aim of this study was to measure these structural ventricular dislocations and set new stereotaxic coordinates for successful and cost-effective ICV invasion 6-18 h after focal cerebral ischaemia. Wistar rats were subjected to 2 h middle cerebral artery occlussion (t-MCAO), were neurologically evaluated (modified Neurological Stroke Scale [mNSS], modified Bederson's Scale [mBS] and grid-walking test [GWT]) and brain slides were studied at 6 and 18 h post-occlusion for infarction volume, hemispheric oedema, middle line dislocation and stereotaxia of the lateral ventricles. Our data indicated that stereotaxic coordinates of the lateral ventricles in the infarcted and contralateral hemispheres significantly (P < 0.05) changed at both time-points and were linearly correlated with the mNSS, mBS and some GWT scores (P < 0.001). This correlation allowed for the calculation of simple (linear) mathematical equations (stereotaxic coordinate = b0 + b1*mNSS, where 'b0' and 'b1' are fixed number and factor, respectively, calculated by regression analysis) that determined individually new coordinates for each animal. Verification experiments revealed that the new coordinates render ICV invasion feasible in up to 80% of infarcted rats (number needed to treat 1.65), compared with only 19.4% using the classical coordinates for normal rats. Therefore, we propose a new, time- and cost-effective methodology for practically feasible ICV invasion in rats 6-18 h after t-MCAO.

A combined scoring method to assess behavioral recovery after mouse spinal cord injury

Although the rat has been the predominant rodent used to investigate the pathophysiology and treatment of experimental spinal cord injury (SCI), the increasing availability of transgenic animals has led to greater use of mouse models. However, behavioral assessment after SCI in mice has been less extensively investigated than in rats and few studies have critically examined the correlation between behavioral tests and injury severity or tissue damage. The present study characterized hindlimb functional performance in C57Bl/6 mice after contusion SCI at T9 using the weight drop method. A number of behavioral tests were examined with regard to variability, inter-rater reliability, and correlation to injury severity and white matter sparing. Mice were subjected to sham, mild-moderate or moderate-severe SCI and evaluated at day 1 and weekly up to 42 days using the Basso mouse scale (BMS), ladder climb, grid walk, inclined plane, plantar test and tail flick tests. The ladder climb and grid walk tests proved sub-optimal for use in mice, but modifications enhanced their predictive value with regard to injury severity. The inclined plane, plantar test and tail flick test showed far too much variability to have meaningful predictive value. The BMS score proved reliable, as previously reported, but a combined score (BLG) using BMS, Ladder climb (modified), and Grip walk (modified grid walk) provided better separation across injury levels and less variability than the individual tests. These data provide support for use of a combined scoring method to follow motor recovery in mice after contusion SCI.

Effects of maternal separation on the neurobehavioral development of newborn Wistar rats

Animal models of neonatal stress, like maternal separation, may provide important correlation with human stress-related disorders. Early maternal deprivation has been shown to cause several short- and long-term neurochemical and behavioral deficits. Little is known about the early neurobehavioral development after postnatal stress. The aim of the present study was to investigate the development of reflexes and motor coordination in male and female pups subjected to maternal deprivation. Pups were removed from their mothers from postnatal day 1–14, for 3 h daily. Somatic development (weight gain, eye opening, ear unfolding, incisor eruption) and reflex development was tested during the first 3 weeks. The appearance of the following reflexes was investigated: crossed extensor, grasping, placing, gait, righting and sensory reflexes, and negative geotaxis. Timely performance of negative geotaxis, righting and gait were also tested daily during the first 3 weeks. Motor coordination and open-field tests were performed on postnatal weeks 3–5 (rotarod, elevated grid-walk, footfault, rope suspension, inclined board and walk initiation tests). The results revealed that a 3-h-long daily maternal separation did not lead to a marked delay or enhancement in reflex development and motor coordination. A subtle enhancement was observed in the appearance of hindlimb grasp and gait reflexes, and a better performance in footfault test in male rats suffering from maternal deprivation. In contrast, female maternally deprived (MD) rats displayed a slight delay in forelimb grasp and air righting reflex appearance, and surface righting performance. Open-field activity was not changed in maternally deprived rats. In summary, our present observations indicate that maternal deprivation does not induce drastic changes in early neurodevelopment, therefore, further research is needed to determine the onset of behavioral alterations in subject with maternal deprivation history. Gender differences described in this study could help to understand how gender-specific differences in early life experience-induced stress-related disorders appear in adult life.

Gender-dependent effects of maternal deprivation on the neurodevelopment of newborn rats

Event Abstract Back to Event Gender-dependent effects of maternal deprivation on the neurodevelopment of newborn rats József Farkas1*, Dóra Reglődi1, Balázs Gaszner1, Donat Szogyi1, Gabor Horvath1, Andrea Lubics1, Andrea Tamas1, Falko Frank1, Dario Besirevic1 and Peter Kiss1 1 Department of Anatomy, University of Pecs, Hungary Early maternal deprivation, a model of neonatal stress, has been shown to cause several short- and long-term neurochemical and behavioral deficits. Little is known about the early neurobehavioral development after postnatal stress. The aim our study was to investigate the development of reflexes and motor coordination in male and female pups subjected to maternal deprivation. Pups were removed from their mothers from postnatal day 1-14, for 3 hours daily. Daily testing during the first 3 weeks was performed for somatic and reflex development (crossed extensor, grasping, placing, gait, righting and sensory reflexes, and negative geotaxis). Timely performance of negative geotaxis, righting and gait were also tested daily. Motor coordination and open-field tests were performed on postnatal weeks 3-5 (rotarod, elevated grid walk, footfault, rope suspension, inclined board and walk initiation tests). The results revealed that a 3-hour-long daily maternal separation did not lead to a marked delay or enhancement in reflex development and motor coordination. A subtle enhancement was observed in the appearance of hindlimb grasp and gait reflexes, and a better performance in footfault test in male rats suffering from maternal deprivation. In contrast, female rats displayed a slight delay in forelimb grasp and air righting reflex appearance, and surface righting performance. Open-field activity was not altered. In summary, our present observations indicate that maternal deprivation does not induce drastic changes in early neurodevelopment. Gender differences described in this study could help to understand how gender-specific differences in early life experience-induced stress-related disorders appear in adult life. Support: OTKA:K72592;F67830;78480 Conference: 12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009. Presentation Type: Poster Presentation Topic: Behavioural neuroscience Citation: Farkas J, Reglődi D, Gaszner B, Szogyi D, Horvath G, Lubics A, Tamas A, Frank F, Besirevic D and Kiss P (2009). Gender-dependent effects of maternal deprivation on the neurodevelopment of newborn rats. Front. Syst. Neurosci. Conference Abstract: 12th Meeting of the Hungarian Neuroscience Society. doi: 10.3389/conf.neuro.01.2009.04.238 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 13 Mar 2009; Published Online: 13 Mar 2009. * Correspondence: József Farkas, Department of Anatomy, University of Pecs, Pecs, Hungary, cjoe840106@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers József Farkas Dóra Reglődi Balázs Gaszner Donat Szogyi Gabor Horvath Andrea Lubics Andrea Tamas Falko Frank Dario Besirevic Peter Kiss Google József Farkas Dóra Reglődi Balázs Gaszner Donat Szogyi Gabor Horvath Andrea Lubics Andrea Tamas Falko Frank Dario Besirevic Peter Kiss Google Scholar József Farkas Dóra Reglődi Balázs Gaszner Donat Szogyi Gabor Horvath Andrea Lubics Andrea Tamas Falko Frank Dario Besirevic Peter Kiss PubMed József Farkas Dóra Reglődi Balázs Gaszner Donat Szogyi Gabor Horvath Andrea Lubics Andrea Tamas Falko Frank Dario Besirevic Peter Kiss Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Effects of perinatal asphyxia on the neurobehavioral and retinal development of newborn rats

Perinatal asphyxia during delivery produces long-term deficits and represents a major problem in both neonatal and pediatric care. Several morphological, biochemical and behavioral changes have been described in rats exposed to perinatal asphyxia. The aim of the present study was to evaluate how perinatal asphyxia affects the complex early neurobehavioral development and retinal structure of newborn rats. Asphyxia was induced in ready-to-deliver mothers by removing the pups by cesarian section after 15 min of asphyxia. Somatic and neurobehavioral development was tested daily during the first 3 weeks, and motor coordination tests were performed on postnatal weeks 3–5. After completion of the testing procedure, retinas were removed for histological analysis. We found that in spite of the fast catch-up-growth of asphyctic pups, nearly all examined reflexes were delayed by 1–4 days: negative geotaxis, sensory reflexes, righting reflexes, development of fore- and hindlimb grasp and placing, gait and auditory startle reflexes. Time to perform negative geotaxis, surface righting and gait reflexes was significantly longer during the first few weeks in asphyctic pups. Among the motor coordination tests, a markedly weaker performance was observed in the grid walking and footfault test and in the walk initiation test. Retinal structure showed severe degeneration in the layer of the photoreceptor and bipolar cell bodies. In summary, our present study provided a detailed description of reflex and motor development following perinatal asphyxia, showing that asphyxia led to a marked delay in neurobehavioral development and a severe retinal degeneration.

Small-Molecule Protein Tyrosine Phosphatase Inhibition as a Neuroprotective Treatment after Spinal Cord Injury in Adult Rats

Spinal cord injury causes progressive secondary tissue degeneration, leaving many injured people with neurological disabilities. There are no satisfactory neuroprotective treatments. Protein tyrosine phosphatases inactivate neurotrophic factor receptors and downstream intracellular signaling molecules. Thus, we tested whether the peroxovanadium compound potassium bisperoxo(1,10-phenanthroline)oxovanadate (V) [bpV(phen)], a stable, potent and selective protein tyrosine phosphatase inhibitor, would be neuroprotective after a thoracic spinal cord contusion in adult rats. Intrathecal bpV(phen) infusions through a lumbar puncture rescued dorsal column sensory axons innervating the nucleus gracilis and white matter at the injury epicenter. At the most effective dose, essentially all of these axons and most of the white matter at the epicenter were spared (vs approximately 60% with control infusions). bpV(phen) treatments started 4 h after contusion were fully effective. This treatment greatly improved and normalized sensorimotor function in a grid-walking test and provided complete axonal protection over 6 weeks. The treatment rescued sensory-evoked potentials that disappeared after dorsal column transection. bpV(phen) affected early degenerative mechanisms, because the main effects were seen at 7 d and lasted beyond the treatment period. The neuroprotection appeared to be mediated by rescue of blood vessels. bpV(phen) reduced apoptosis of cultured endothelial cells. These results show that a small molecule, used in a clinically relevant manner, reduces loss of long-projecting axons, myelin, blood vessels, and function in a model relevant to the most common type of spinal cord injury in humans. They reveal a novel mechanism of spinal cord degeneration involving protein tyrosine phosphatases that can be targeted with therapeutic drugs.

Effectiveness of a new modified intraluminal suture for temporary middle cerebral artery occlusion in rats of various weight

Intraluminal temporary middle cerebral artery occlusion (MCAO) is a common model of ischemic stroke in the rat with significant, suture and weight-dependent variability along with increased risk of subarachnoid haemorrhage (SAH). Our purpose was to increase reproducibility and decrease SAH using a modification of the Koizumi suture. We compared a Koizumi 5/0 Ethilon poly- l-lysine-coated suture (s-2, group B) to an identical, uncoated one (s-1, group A) and the Belayev's 3/0 suture (s-3, group C), in the 2-h MCAO model in Wistar rats of varying weight (310–527 g). Assessment included successful infarction rates, the modified neurological stroke scale (mNSS), a modified Bederson's scale (mBS), the grid-walking test (GWT), infarction volume (with rostrocaudal subanalysis and analysis of cortical/striatal involvement) and hemispheric edema. The s-2 suture increased the successful MCAO from 61.1% and 66.6% (groups A and C) to 97.5% in group B and induced a more severe clinical stroke ( P < 0.05) irrespective of animal's weight, with no incidence of SAH. Infarction volume and ipsilateral hemispheric edema significantly ( P < 0.05) increased and well correlated with the mNSS ( P ≤ 0.005), the mBS ( P ≤ 0.01) and GWT outcomes. Our data suggest that the new modified suture induces a more reproducible ischemic stroke in Wistar rats for temporary-MCAO experiments, overcoming the variability of weight and the risk of SAH.

Long-Term Functional and Protective Actions of Preconditioning With Hypoxia, Cobalt Chloride, and Desferrioxamine Against Hypoxic-Ischemic Injury in Neonatal Rats

Preconditioning with hypoxia and hypoxia-mimetic compounds cobalt chloride (CoCl2) and desferrioxamine (DFX) protects against hypoxic-ischemic (HI) injury in neonatal rat brain. We examined long-term functional and protective actions of preconditioning induced by hypoxia, CoCl(2) and DFX in a neonatal rat model of HI. Postnatal day six rat pups were exposed to preconditioning with hypoxia (8% oxygen) or injections of CoCl(2), DFX or saline vehicle and 24 h later rats underwent HI or sham surgery. Behavioral tests were performed and at the conclusion of experiments, brains removed for morphologic analyses. HI resulted in a large unilateral lesion in the ipsilateral hemisphere compared with sham control rats. All preconditioning treatments significantly reduced the total lesion volume. Behavioral deficits were observed in HI rats compared with sham controls. The reduction in forelimb grasping strength in HI rats was attenuated by preconditioning with hypoxia, CoCl(2) and DFX. HI increased the number of foot faults in a grid-walking test and resulted in forelimb asymmetry in the cylinder test. Only preconditioning with hypoxia reversed all three functional deficits after HI. These findings indicate that preconditioning, especially when induced by hypoxia, has the potential to minimize the morphologic and functional effects of neonatal HI injury.

Detrimental Effects of Aging on Outcome from Traumatic Brain Injury: A Behavioral, Magnetic Resonance Imaging, and Histological Study in Mice

Considerable evidence indicates that outcomes from traumatic brain injury (TBI) are worse in the elderly, but there has been little preclinical research to explore potential mechanisms. In this study, we examined the age-related effects on outcome in a mouse model of controlled cortical impact (CCI) injury. We compared the responses of adult (5-6 months old) and aged (21-24 months old) male mice following a moderate lateral CCI injury to the sensorimotor cortex. Sensorimotor function was evaluated with the rotarod, gridwalk and spontaneous forelimb behavioral tests. Acute edema was assessed from hyperintensity on T2-weighted magnetic resonance images. Blood-brain barrier opening was measured using anti-mouse immunoglobulin G (IgG) immunohistochemistry. Neurodegeneration was assessed by amino-cupric silver staining, and lesion cavity volumes were measured from histological images. Indicators of injury were generally worse in the aged than the adult mice. Acute edema, measured at 24 and 48 h post-injury, resolved more slowly in the aged mice (p < 0.01). Rotarod recovery (p < 0.05) and gridwalk deficits (p < 0.01) were significantly worse in aged mice. There was greater (p < 0.01 at 3 days) and more prolonged post-acute opening of the blood-brain barrier in the aged mice. Neurodegeneration was greater in the aged mice (p < 0.01 at 3 days). In contrast, lesion cavity volumes, measured at 3 days post-injury, were not different between injured groups. These results suggest that following moderate controlled cortical impact injury, the aged brain is more vulnerable than the adult brain to neurodegeneration, resulting in greater loss of function. Tissue loss at the impact site does not explain the increased functional deficits seen in the aged animals. Prolonged acute edema, increased opening of the blood-brain barrier and increased neurodegeneration found in the aged animals implicate secondary processes in age-related differences in outcome.