Wire Hang Research Articles

Haploinsufficiency of the E3 ubiquitin ligase C-terminus of heat shock cognate 70 interacting protein (CHIP) produces specific behavioral impairments.

The multifunctional E3 ubiquitin ligase CHIP is an essential interacting partner of HSP70, which together promote the proteasomal degradation of client proteins. Acute CHIP overexpression provides neuroprotection against neurotoxic mitochondrial stress, glucocorticoids, and accumulation of toxic amyloid fragments, as well as genetic mutations in other E3 ligases, which have been shown to result in familial Parkinson's disease. These studies have created a great deal of interest in understanding CHIP activity, expression and modulation. While CHIP knockout mice have the potential to provide essential insights into the molecular control of cell fate and survival, the animals have been difficult to characterize in vivo due to severe phenotypic and behavioral dysfunction, which have thus far been poorly characterized. Therefore, in the present study we conducted a battery of neurobehavioral and physiological assays of adult CHIP heterozygotic (HET) mutant mice to provide a better understanding of the functional consequence of CHIP deficiency. We found that CHIP HET mice had normal body and brain weight, body temperature, muscle tone and breathing patterns, but do have a significant elevation in baseline heart rate. Meanwhile basic behavioral screens of sensory, motor, emotional and cognitive functions were normative. We observed no alterations in performance in the elevated plus maze, light-dark preference and tail suspension assays, or two simple cognitive tasks: novel object recognition and spontaneous alternation in a Y maze. Significant deficits were found, however, when CHIP HET mice performed wire hang, inverted screen, wire maneuver, and open field tasks. Taken together, our data indicate a clear subset of behaviors that are altered at baseline in CHIP deficient animals, which will further guide whole animal studies of the effects of CHIP dysregulation on cardiac function, brain circuitry and function, and responsiveness to environmental and cellular stress.

Evidence of a progressive motor dysfunction in Mucopolysaccharidosis type I mice

Mucopolysaccharidosis (MPS) type I (Hurler syndrome) is a lysosomal storage disorder characterized by deficiency of alpha-l-iduronidase (IDUA), intracellular storage of glycosaminoglycans (GAGs) and progressive neurological pathology. The MPS I mouse model provides an opportunity to study the pathophysiology of this disorder and to determine the efficacy of novel therapies. Previous work has demonstrated a series of abnormalities in MPS I mice behavior, but so far some important brain functions have not been addressed. Therefore, in the present study we aimed to determine if MPS I mice have motor abnormalities, and at what age they become detectable. MPS I and normal male mice from 2 to 8 months of age were tested in open-field for locomotor activity, hindlimb gait analysis and hang wire performance. We were able to detect a progressive reduction in the crossings and rearings in the open field test and in the hang wire test in MPS I mice from 4 months, as well as a reduction in the gait length at 8 months. Histological examination of 8-month old mice cortex and cerebellum revealed storage of GAGs in Purkinje cells and neuroinflammation, evidenced by GFAP immunostaining. However TUNEL staining was negative, suggesting that death does not occur. Our findings suggest that MPS I mice have a progressive motor dysfunction, which is not caused by loss of neuron cells but might be related to a neuroinflammatory process.

Protection by an antioxidant of rotenone-induced neuromotor decline, reactive oxygen species generation and cellular stress in mouse brain

Exposure to environmental toxins, including rotenone, results in central nervous system and systemic toxicity. Rotenone is a widely used pesticide and a mitochondrial complex I (CI) inhibitor. This study reports effectiveness of a synthetic lipoylcarnitine antioxidant compound, lipoylcarnitine methyl ester iodide (PMX-500F), for treatment of chronic rotenone induced neurological deficits in mice. Mice (C57BL/6NTac; two months of age) received oral administration of rotenone (30mg/kg/day) or vehicle, preceded by intraperitoneal injection of PMX-500F (19mg/kg) or vehicle for four weeks. In the Rota-rod test, rotenone treatment had no effect (P>0.05); however, PMX-500F treatment improved locomotor coordination and endurance (latency to fall time; P<0.05). For neuromuscular strength (wire hang test), rotenone treated mice showed reduced latency to fall compared to control mice (P<0.05). PMX-500F treatment improved the outcome in both control and rotenone exposed mice (P<0.05). Rotenone administration increased ROS generation in the forebrain and midbrain regions, but not in the cerebellum (P<0.05). Co-treatment with PMX-500F normalized the ROS in forebrain and midbrain regions to that of the control concentrations. In rotenone administered mice, activated stress-activated protein kinase/c-Jun NH2-terminal kinase (pSAPK/JNK) was higher in forebrain and midbrain lysates than in control mice (P<0.05) and treatment with PMX-500F reduced pSAPK/JNK to control levels. The pSAPK/JNK levels in the cerebellum were similar in all four groups (P>0.05). Total SAPK/JNK was not altered by either rotenone or PMX-500F treatment (P>0.05). These results illustrate that an antioxidant, here PMX-500F, provides protection against rotenone induced decline in neuromotor function, reactive oxygen species (ROS) generation and cellular stress.

Nuclear expression of a mitochondrial DNA gene: mitochondrial targeting of allotopically expressed mutant ATP6 in transgenic mice.

Nuclear encoding of mitochondrial DNA transgenes followed by mitochondrial targeting of the expressed proteins (allotopic expression; AE) represents a potentially powerful strategy for creating animal models of mtDNA disease. Mice were created that allotopically express either a mutant (A6M) or wildtype (A6W) mt-Atp6 transgene. Compared to non-transgenic controls, A6M mice displayed neuromuscular and motor deficiencies (wire hang, pole, and balance beam analyses; P < 0.05), no locomotor differences (gait analysis; P < 0.05) and enhanced endurance in Rota-Rod evaluations (P < 0.05). A6W mice exhibited inferior muscle strength (wire hang test; P < 0.05), no difference in balance beam footsteps, accelerating Rota-Rod, pole test and gait analyses; (P < 0.05) and superior performance in balance beam time-to-cross and constant velocity Rota-Rod analyses (P < 0.05) in comparison to non-transgenic control mice. Mice of both transgenic lines did not differ from non-transgenic controls in a number of bioenergetic and biochemical tests including measurements of serum lactate and mitochondrial MnSOD protein levels, ATP synthesis rate, and oxygen consumption (P > 0.05). This study illustrates a mouse model capable of circumventing in vivo mitochondrial mutations. Moreover, it provides evidence supporting AE as a tool for mtDNA disease research with implications in development of DNA-based therapeutics.

TRPV4 Channels in Mouse Skeletal Muscle: Gene Expression, Role for Ca2+ Homeostasis and Muscle Force and Fatigue

The cation channel TRPV4 is one of the most abundant TRP channels in mouse skeletal muscle. Here, we investigated the contribution of TRPV4 to Ca2+ homeostasis, muscle force and fatigue. For this we used muscles of wildtype (WT) and TRPV4-/- mice. To estimate background Ca2+ influx we applied the Mn2+ quench technique. Muscle force was tested on isolated soleus muscles. Gene expression was analyzed by RT-PCR and data normalized to that of 18s rRNA. In WT fibers application of 4a-PDD, a TRPV4 activator, caused an increase in the Mn2+ quench rate of about 45 % (4.27 ± 0.24 %/min vs. 6.28 ± 0.39 %/min, p<0.01). This effect was completely absent in TRPV4-/- fibers. However, basic quench was not reduced in TRPV4 deficient fibers. Decay time of KCl induced Ca2+-transients was increased in WT fibers after application of 4-αPDD (from 4.46 ± 0.2 s, n=67 to 5.92 ± 0.28 s, n=23, p < 0.01). This effect was likewise not observed in fibers of TRPV4-/- animals. Muscle fatigue was attenuated in the presence of 4α-PDD, an effect which was not observed in muscles of TRPV4-/- mice. No difference between TRPV4-/- and WT animals was seen in wire hang test. Gene expression analysis showed that TRPV4 and TRPV2 were the most abundant TRPV channels in muscle, their mRNA concentration being about 5-fold higher in soleus muscle that in fast twitch EDL. In soleus muscles of TRPV4-/- mice TRPV2 mRNA was significantly increased. We conclude that TRPV4 is functionally expressed in mouse skeletal muscle, contributes to background calcium entry and can modulate Ca2+ transients. TRPV4 activity can attenuate fatigue, but its lack does not affect gross motor skills. TRPV4 knockout causes a compensatory upregulation of TRPV2.

ATP7A Gene Addition to the Choroid Plexus Results in Long-term Rescue of the Lethal Copper Transport Defect in a Menkes Disease Mouse Model

Menkes disease is a lethal infantile neurodegenerative disorder of copper metabolism caused by mutations in a P-type ATPase, ATP7A. Currently available treatment (daily subcutaneous copper injections) is not entirely effective in the majority of affected individuals. The mottled-brindled (mo-br) mouse recapitulates the Menkes phenotype, including abnormal copper transport to the brain owing to mutation in the murine homolog, Atp7a, and dies by 14 days of age. We documented that mo-br mice on C57BL/6 background were not rescued by peripheral copper administration, and used this model to evaluate brain-directed therapies. Neonatal mo-br mice received lateral ventricle injections of either adeno-associated virus serotype 5 (AAV5) harboring a reduced-size human ATP7A (rsATP7A) complementary DNA (cDNA), copper chloride, or both. AAV5-rsATP7A showed selective transduction of choroid plexus epithelia and AAV5-rsATP7A plus copper combination treatment rescued mo-br mice; 86% survived to weaning (21 days), median survival increased to 43 days, 37% lived beyond 100 days, and 22% survived to the study end point (300 days). This synergistic treatment effect correlated with increased brain copper levels, enhanced activity of dopamine-β-hydroxylase, a copper-dependent enzyme, and correction of brain pathology. Our findings provide the first definitive evidence that gene therapy may have clinical utility in the treatment of Menkes disease.

GSPE interferes with tau aggregation in vivo: implication for treating tauopathy

Tauopathies are characterized by progressive neurodegeneration caused by intracellular accumulation of hyperphosphorylated tau protein aggregates in the brain. The present study was designed to test whether a grape seed polyphenolic extract (GSPE) previously shown to inhibit tau protein aggregation in vitro could benefit tau-mediated neuropathology and behavior deficits in JNPL3 transgenic mice expressing a human tau protein containing the P301L mutation. Nine-month-old JNPL3 mice were treated with GSPE delivered through their drinking water for 6 months. We found that GSPE treatment significantly reduced the number of motor neurons immunoreactive for hyperphosphorylated and conformationally-modified tau in the ventral horns of the spinal cord identified using AT100, PHF-1, AT8, and Alz50 tau antibodies. This coincided with a drastically reduced level of hyperphosphorylated and sarcosyl-insoluble tau in spinal cord fractions. Furthermore, the reduction of tau pathology was accompanied by an improvement in the motor function assessed by a wire hang test. Collectively, our results suggest that GSPE can interfere with tau-mediated neurodegenerative mechanisms and ameliorate neurodegenerative phenotype in an animal model of tauopathy. Our studies support further evaluation of GSPE for preventing and/or treating of tauopathies in humans.

E46K Human α-Synuclein Transgenic Mice Develop Lewy-like and Tau Pathology Associated with Age-dependent, Detrimental Motor Impairment

Synucleinopathies are a group of neurodegenerative disorders associated with the formation of aberrant amyloid inclusions composed of the normally soluble presynaptic protein α-synuclein (α-syn). Parkinson disease is the most well known of these disorders because it bears α-syn pathological inclusions known as Lewy bodies (LBs). Mutations in the gene for α-syn, including the E46K missense mutation, are sufficient to cause Parkinson disease as well as other synucleinopathies like dementia with LBs. Herein, we describe transgenic mice expressing E46K human α-syn in CNS neurons that develop detrimental age-dependent motor impairments. These animals accumulate age-dependent intracytoplasmic neuronal α-syn inclusions that parallel disease and recapitulate the biochemical, histological, and morphological properties of LBs. Surprisingly, the morphology of α-syn inclusions in E46K human α-syn transgenic mice more closely resemble LBs than the previously described transgenic mice (line M83) that express neuronal A53T human α-syn. E46K human α-syn mice also develop abundant neuronal tau inclusions that resemble neurofibrillary tangles. Subsequent studies on the ability of E46K α-syn to induce tau inclusions in cellular models suggest that both direct and indirect mechanisms of protein aggregation are probably involved in the formation of the tau inclusions observed here in vivo. Re-evaluation of presymptomatic transgenic mice expressing A53T human α-syn reveals that the formation of α-syn inclusions in mice must be synchronized; however, inclusion formation is diffuse within affected areas of the neuroaxis such that there was no clustering of inclusions. Collectively, these findings provide insights in the mechanisms of formation of these aberrant proteinaceous inclusions and support the notion that α-syn aggregates are involved in the pathogenesis of human diseases.

Permanent deficits in brain functions caused by long-term ketamine treatment in mice

Ketamine, an injectable anesthetic, is also a popular recreational drug used by young adults worldwide. Ketamine is a non-competitive antagonist of N-methyl-d-aspartate receptor, which plays important roles in synaptic plasticity and neuronal learning. Most previous studies have examined the immediate and short-term effects of ketamine, which include learning and cognitive deficits plus impairment of working memory, whereas little is known about the long-term effects of repeated ketamine injections of common or usual recreational doses. Therefore, we aimed to evaluate the deficits in brain functions with behavioral tests, including wire hang, hot plate and water maze tests, plus examine prefrontal cortex apoptotic markers, including Bax, Bcl-2 and caspase-3, in mice treated with 6 months of daily ketamine administration. In our study, following 6 months of ketamine injection, mice showed significant deterioration in neuromuscular strength and nociception 4 hours post-dose, but learning and working memory were not affected nor was there significant apoptosis in the prefrontal cortex. Our research revealed the important clinical finding that long-term ketamine abuse with usual recreational doses can detrimentally affect neuromuscular strength and nociception as part of measurable, stable and persistent deficits in brain function.

Sociability and motor functions in Shank1 mutant mice

Autism is a neurodevelopmental disorder characterized by aberrant reciprocal social interactions, impaired communication, and repetitive behaviors. While the etiology remains unclear, strong evidence exists for a genetic component, and several synaptic genes have been implicated. SHANK genes encode a family of synaptic scaffolding proteins located postsynaptically on excitatory synapses. Mutations in SHANK genes have been detected in several autistic individuals. To understand the consequences of SHANK mutations relevant to the diagnostic and associated symptoms of autism, comprehensive behavioral phenotyping on a line of Shank1 mutant mice was conducted on multiple measures of social interactions, social olfaction, repetitive behaviors, anxiety-related behaviors, motor functions, and a series of control measures for physical abilities. Results from our comprehensive behavioral phenotyping battery indicated that adult Shank1 null mutant mice were similar to their wildtype and heterozygous littermates on standardized measures of general health, neurological reflexes and sensory skills. Motor functions were reduced in the null mutants on open field activity, rotarod, and wire hang, replicating and extending previous findings (Hung et al., 2008). A partial anxiety-like phenotype was detected in the null mutants in some components of the light ↔ dark task, as previously reported (Hung et al., 2008) but not in the elevated plus-maze. Juvenile reciprocal social interactions did not differ across genotypes. Interpretation of adult social approach was confounded by a lack of normal sociability in wildtype and heterozygous littermates. All genotypes were able to discriminate social odors on an olfactory habituation/dishabituation task. All genotypes displayed relatively high levels of repetitive self-grooming. Our findings support the interpretation that Shank1 null mice do not demonstrate autism-relevant social interaction deficits, but confirm and extend a role for Shank1 in motor functions.

Heterozygous B6;C3‐Opa1Q285STOP mouse model of dominant optic atrophy displays subtle neuromuscular features with age

Abstract Purpose OPA1 autosomal dominant optic atrophy is a slowly progressive optic neuropathy. A neurological ‘plus’ phenotype has been reported with some OPA1 mutations, prompting further systemic evaluation of our mouse model. Heterozygous Opa1 mutant mice (B6;C3‐Opa1Q285STOP), with documented visual defects on optokinetic drum tracking and optic nerve defects on electron microscopy, were assessed. Here we explore neuromuscular aspects of the phenotype. Methods Published husbandry and genotyping protocols were used. Body weight, SHIRPA test, accelerating rotarod and visual acuity testing using the optokinetic drum was carried out. Results Mean weights of all Opa1 male and female mice over 6 months age showed a trend towards lighter weight in Opa1+/‐ mice (WT 32.74g, SD=6.0; Het 29.47g, SD=2.7 ; p&gt; 0.05). By 20 months of age there was a statistically significant difference between WT and Hets (WT 40.6g, SD=3.1; Het 28.77g, SD=2.44; p&lt; 0.05). SHIRPA neurological screen of 12 month old animals showed that Opa1+/‐ (Hets) were less active than wild type (WT) in an open arena (p&lt;0.05), and less able to perform the wire hang test (p&lt;0.05). 12 month Opa1+/‐ showed reduced mean performance on rotarod (WT 92s, SD=10; Het 70s, SD=20.9; p=0.05). Rotarod testing at 20 months was discontinued since grossly obese wild type mice were unable to perform the test and act as controls. Conclusion Opa1+/‐ mice are lighter than WT age and sex matched controls. Rotarod testing confirms a subtle neuromuscular defect in Opa1+/‐ mice in line with neurological (SHIRPA) testing.

Evaluation of Systemic Follistatin as an Adjuvant to Stimulate Muscle Repair and Improve Motor Function in Pompe Mice

Due to the lack of acid alpha-glucosidase (GAA) activity, Pompe mice develop glycogen storage pathology and progressive skeletal muscle dysfunction with age. Applying either gene or enzyme therapy to reconstitute GAA levels in older, symptomatic Pompe mice effectively reduces glycogen storage in skeletal muscle but provides only modest improvements in motor function. As strategies to stimulate muscle hypertrophy, such as by myostatin inhibition, have been shown to improve muscle pathology and strength in mouse models of muscular dystrophy, we sought to determine whether these benefits might be similarly realized in Pompe mice. Administration of a recombinant adeno-associated virus serotype 8 vector encoding follistatin, an inhibitor of myostatin, increased muscle mass and strength but only in Pompe mice that were treated before 10 months of age. Younger Pompe mice showed significant muscle fiber hypertrophy in response to treatment with follistatin, but maximal gains in muscle strength were achieved only when concomitant GAA administration reduced glycogen storage in the affected muscles. Despite increased grip strength, follistatin treatment failed to improve rotarod performance. These findings highlight the importance of treating Pompe skeletal muscle before pathology becomes irreversible, and suggest that adjunctive therapies may not be effective without first clearing skeletal muscle glycogen storage with GAA.

Systemic transplantation of mesenchymal stem cells can reduce cognitive and motor deficits in rats with unilateral lesions of the neostriatum

Huntington’s disease (HD) is an inherited neurodegenerative disorder that usually occurs in the third or fourth decades of life. Stem cell therapy is one of the approaches for HD treatment. Since mesenchymal stem cells (MSCs) have the ability to migrate into the lesioned site, we transplanted rat bone marrow-derived MSCs intravenously, following unilateral intrastriatal lesion made by quinolinic acid (QA) in Wistar rats. QA administration caused widespread neuropathological deficits similar to those found in HD, including impairments in motor and cognitive functions. Animals receiving MSCs exhibited significant improvement in motor and cognitive performance compared with sham group animals that did not receive cells. Animals were tested by apomorphine-induced rotations, beam walk, cylinder and hang wire tests at different times after cell transplantation. Results indicate that systemic transplantation of MSCs can significantly reduce the behavioral abnormalities of these animals. This method of systemic injection has a great advantage over invasive surgical techniques for transplantation of cells at the lesioned site.

The primary locus of motor neuron death in an ALS–PDC mouse model

A mouse model of amyotrophic lateral sclerosis-parkinsonism-dementia complex based on the consumption of cycad seed flour was used to determine whether the observed pathology of motor neuron loss begins in the distal axons or the spinal cord. Assessments of neuromuscular junction integrity and motor neurons were performed at multiple time points. Mice fed cycad pellets performed worse on the wire hang than controls. Microglial activation in cycad-fed mice was observed with motor neuron degeneration at 12 weeks, but reactive astrocyte proliferation was not observed. After 33 weeks of cycad feeding, motor neuron loss had stabilized, with no evidence of neuromuscular junction endplate denervation. These data suggest that neuronal pathology begins at the soma and proceeds distally in a 'dying forward' pattern.

Decreased physical function and increased pain sensitivity in mice deficient for type IX collagen

In mice with Col9a1 gene inactivation (Col9a1(-/-)), osteoarthritis (OA) and intervertebral disc degeneration develop prematurely. The aim of this study was to investigate Col9a1(-/-) mice for functional and symptomatic changes that may be associated with these pathologies. Col9a1(-/-) and wild-type mice were investigated for reflexes, functional impairment (beam walking, pole climbing, wire hang, grip strength), sensorimotor skills (rotarod), mechanical sensitivity (von Frey hair), and thermal sensitivity (hot plate/tail flick). Gait was also analyzed to determine velocity, stride frequency, symmetry, percentage stance time, stride length, and step width. Postmortem, sera obtained from the mice were analyzed for hyaluronan, and their knees and spines were graded histologically for degeneration. Col9a1(-/-) mice had compensatory gait changes, increased mechanical sensitivity, and impaired physical ability. Col9a1(-/-) mice ambulated with gaits characterized by increased percentage stance times and shorter stride lengths. These mice also had heightened mechanical sensitivity and were deficient in contact righting, wire hang, rotarod, and pole climbing tasks. Male Col9a1(-/-) mice had the highest mean serum hyaluronan levels and strong histologic evidence of cartilage erosion. Intervertebral disc degeneration was also detected, with Col9a1(-/-) mice having an increased incidence of disc tears. These data describe a Col9a1(-/-) behavioral phenotype characterized by altered gait, increased mechanical sensitivity, and impaired function. These gait and functional differences suggest that Col9a1(-/-) mice select locomotive behaviors that limit joint loads. The nature and magnitude of behavioral changes were largest in male mice, which also had the greatest evidence of knee degeneration. These findings suggest that Col9a1(-/-) mice present behavioral changes consistent with anatomic signs of OA and intervertebral disc degeneration.

Las ratas tratadas con el suplemento dietético Vitamix® (Ceregumil® con vitaminas) muestran mayor resistencia física y capacidad antioxidante

Vitamix® is a dietary product composed of a hydro-alcoholic extract of cereals and pulses with honey, calcium glycerophosphate, vitamins B and D, selenium and fluoride. The basic product, Ceregumil®, patented in 1912, was highly popular as tonic and consumers reported a feeling of health, resistance to illness, and increased predisposition to work and exercise. In the present study we analysed the effect of Vitamix® used as dietary supplement, on several physiological parameters in laboratory rats. We periodically performed hemograms and measured intake and weight, as well as blood levels of glucose, triglycerides, cholesterol, transaminases and malondialdehyde, a lipoperoxidation product. Physical probes were performed and a histochemical study was done in the liver. Rats fed with Vitamix® displayed lower intake and body weight in adult ages, showed and increased antioxidant activity, higher resistance in the wire hang test and lower fatigue in the Morris pool, specially those specimens considered as bad performers supplemented with Vitamix®. The rest of the measured parameters remained similar to control and no hepatic alterations were found. This study supports a scientific basis to know the effect of these complements over physiological parameters.

Brief Exposure to Hyperoxia Depletes the Glial Progenitor Pool and Impairs Functional Recovery after Hypoxic-Ischemic Brain Injury

Patterns of hypoxic-ischemic brain injury in infants and children suggest vulnerability in regions of white matter development, and injured patients develop defects in myelination resulting in cerebral palsy and motor deficits. Reperfusion exacerbates the oxidative stress that occurs after such injuries and may impair recovery. Resuscitation after hypoxic-ischemic injury is routinely performed using 100% oxygen, and this practice may increase the oxidative stress that occurs during reperfusion and further damage an already compromised brain. We show that brief exposure (30 mins) to 100% oxygen during reperfusion worsens the histologic injury in young mice after unilateral brain hypoxia-ischemia, causes an accumulation of the oxidative metabolite nitrotyrosine, and depletes preoligodendrocyte glial progenitors present in the cortex. This damage can be reversed with administration of the antioxidant ebselen, a glutathione peroxidase mimetic. Moreover, mice recovered in 100% oxygen have a more disrupted pattern of myelination and develop a static motor deficit that mimics cerebral palsy and manifests itself by significantly worse performance on wire hang and rotorod motor testing. We conclude that exposure to 100% oxygen during reperfusion after hypoxic-ischemic brain injury increases secondary neural injury, depletes developing glial progenitors, interferes with myelination, and ultimately impairs functional recovery.

Comparative analysis of anxiety-like behaviors and sensorimotor functions in two rat mutants, ci2 and ci3, with lateralized rotational behavior

There is increasing evidence that developmental anomalies of cerebral asymmetry are involved in the etiology of psychiatric disorders, including schizophrenia, depression and anxiety. Thus, rodents with abnormal cerebral lateralization are interesting tools to study the association between such anomalies and behavioral dysfunction. The most studied indicator of cerebral asymmetry in the rat is that of circling or rotational behavior. We have recently described two rat mutants, ci2 and ci3, in which lateralized rotational behavior occurs either spontaneously or in response to external stimuli, such as new environment or handling. While cochlear and vestibular defects are found in ci2 rats, ci3 rats do not exhibit any inner ear abnormalities. The abnormal motor response to external stimuli raised the possibility that the circling rat mutants may be more likely to express anxiety-related behavior in tests of emotionality. In the present study, we characterized anxiety-related behaviors of ci2 and ci3 rats in the open field, elevated plus-maze and light/dark exploration test. Furthermore, sensorimotor functions of these rats were evaluated by the rotarod, accelerod and wire hang tests. Heterozygous (ci2/+) littermates or rats of the respective background strains (LEW, BH.7A) were used as controls. In contrast to our expectation, both mutants demonstrated less anxiety-related behavior than controls in tests of emotionality. Ci3 rats exhibited normal sensorimotor functions, whereas marked impairment was observed in ci2 rats, which is most likely a consequence of the vestibular dysfunction in these animals. The acoustic startle response (ASR) and prepulse inhibition of ASR did not differ between ci3 rats and controls. The reduced emotionality of the mutant rats indicated by the present experiments may not be specifically linked to anxiety per se, but is maybe more reflective of impulsivity or the inability to normally perceive or process potentially threatening situations. Based on previous findings of dysfunctions of the central dopamine system in ci2 and ci3 mutant rats, we assume that alterations in dopaminergic activity are involved in the maladaptive behavior observed in the present study.

Reactivity assays for non-animal based prediction of skin sensitisation potential

Valproate has been used for over 30 years as a first-line treatment for epilepsy. In recent years, prenatal exposure to valproate has been associated with teratogenic effects, limiting its use in women that are pregnant or of childbearing age. However, despite its potential detrimental effects on development, valproate continues to be prescribed at high rates in pediatric populations in some countries. Animal models allow us to test hypotheses regarding the potential effects of postnatal valproate exposure on neurobehavioral development, as well as identify potential mechanisms mediating observed effects. Here, we tested the effect of early postnatal (P4–P11) valproate exposure (100 mg/kg and 200 mg/kg) on motor and affective development in two strains of mice, SVE129 and C57Bl/6N. We also assessed the effect of early valproate exposure on regional BDNF protein levels, a potential target of valproate, and mediator of neurodevelopmental outcomes. We found that early life valproate exposure led to significant motor impairments in both SVE129 and C57Bl/6N mice. Both lines of mice showed significant delays in weight gain, as well as impairments in the righting reflex (P7–8), wire hang (P17), open field (P12 and P21), and rotarod (P25 and P45) tasks. Interestingly, some of the early locomotor effects were strain- and dose-dependent. We observed no effects of valproate on early markers of anxiety-like behavior. Importantly, early life valproate exposure had significant effects on regional BDNF expression, leading to a near 50% decrease in BDNF levels in the cerebellum of both strains of mice, while not impacting hippocampal BDNF protein levels. These observations indicate that postnatal exposure to valproate may have significant, and region-specific effects, on neural and behavioral development, with specific consequences for cerebellar development and motor function.

Central Nervous System-directed AAV2/5-Mediated Gene Therapy Synergizes with Bone Marrow Transplantation in the Murine Model of Globoid-cell Leukodystrophy

Globoid-cell leukodystrophy (GLD) is a rapidly progressing inherited neurodegenerative disorder caused by a deficiency in galactosylceramidase activity. Previous studies in the murine model of GLD (Twitcher mouse) have shown that both bone marrow transplantation (BMT) and central nervous system (CNS)-directed gene therapy can be moderately effective at ameliorating certain aspects of GLD. As BMT and CNS-directed gene therapy target fundamentally different tissues, we tested the hypothesis that combining these disparate therapies would be more efficacious than either therapy alone. Mice receiving myeloreductive conditioning at birth followed by syngeneic BMT had approximately 25-35% donor chimerism. Untreated Twitcher mice, Twitcher mice treated with BMT alone, AAV2/5 alone, or a combination of BMT and AAV2/5 had mean lifespans of 39, 44, 49, and 104 days, respectively. Twitcher mice treated with a combination of BMT and AAV2/5 also had significantly improved performance in several behavioral tests and greater reduction in demyelination, astrocytosis, and macrophage infiltration compared to untreated Twitcher mice or mice that received either therapy alone. These data suggest that CNS-directed gene therapy synergizes with BMT. The combination of these disparate therapeutic approaches may form the basis for more effective treatment of this inherited neurodegenerative disorder.