Four-parameter analysis in modified Rotarod test for detecting minor motor deficits in mice

Inhibiting SHP2 reduces glycolysis, promotes microglial M1 polarization, and alleviates secondary inflammation following spinal cord injury in a mouse model

JOURNAL/nrgr/04.03/01300535-202503000-00030/figure1/v/2024-06-17T092413Z/r/image-tiff Reducing the secondary inflammatory response, which is partly mediated by microglia, is a key focus in the treatment of spinal cord injury. Src homology 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, is widely expressed in the human body and plays a role in inflammation through various mechanisms. Therefore, SHP2 is considered a potential target for the treatment of inflammation-related diseases. However, its role in secondary inflammation after spinal cord injury remains unclear. In this study, SHP2 was found to be abundantly expressed in microglia at the site of spinal cord injury. Inhibition of SHP2 expression using siRNA and SHP2 inhibitors attenuated the microglial inflammatory response in an in vitro lipopolysaccharide-induced model of inflammation. Notably, after treatment with SHP2 inhibitors, mice with spinal cord injury exhibited significantly improved hind limb locomotor function and reduced residual urine volume in the bladder. Subsequent in vitro experiments showed that, in microglia stimulated with lipopolysaccharide, inhibiting SHP2 expression promoted M2 polarization and inhibited M1 polarization. Finally, a co-culture experiment was conducted to assess the effect of microglia treated with SHP2 inhibitors on neuronal cells. The results demonstrated that inflammatory factors produced by microglia promoted neuronal apoptosis, while inhibiting SHP2 expression mitigated these effects. Collectively, our findings suggest that SHP2 enhances secondary inflammation and neuronal damage subsequent to spinal cord injury by modulating microglial phenotype. Therefore, inhibiting SHP2 alleviates the inflammatory response in mice with spinal cord injury and promotes functional recovery postinjury.

Stimulation of central histaminergic transmission attenuates diazepam-induced motor disturbance on rota-rod and beam walking tests in mice

Diazepam administration has been shown to influence the release of histamine in various brain areas involved in motor behavior. Therefore, the present study explored the plausible regulatory role of the central histaminergic system in diazepam-induced deficits in motor performance in mice using the rota-rod and beam walking tests. In this study, several doses of diazepam (0.5, 1, 2, and 3 mg/kg, i.p.) were assessed in mice for changes in motor performance on the rota-rod and beam walking test. In addition, the brain histamine levels were determined after diazepam administration, and the diazepam-induced motor deficits were assessed in mice, pretreated centrally (intracerebroventricular) with histaminergic agents such as histamine (0.1, 10 µg), histamine precursor (L-histidine: 0.1, 2.5 µg), histamine neuronal releaser/H 3 receptor antagonist (thioperamide: 0.5, 10 µg), H 1 and H 2 receptor agonist [2-(3-trifluoromethylphenyl) histamine (FMPH: 0.1, 6.5 µg; amthamine: 0.1, 5 µg)/antagonist (H 1 : cetirizine 0.1 µg) and (H 2 : ranitidine: 50 µg)]. Results indicate that mice treated with diazepam at doses 1, 2 mg/kg, i.p. significantly increased the brain histamine levels. Moreover, in mice pretreated with histaminergic transmission-enhancing agents, the diazepam (2 mg/kg, i.p.)-induced motor incoordination was significantly reversed. Contrastingly, diazepam (1 mg/kg, i.p.) in its subeffective dose produced significant motor deficits in mice preintracerebroventricular injected with histamine H 1 and H 2 receptor antagonists on both the employed tests. Therefore, it is postulated that endogenous histamine operates via H 1 and H 2 receptor activation to alleviate the motor-impairing effects of diazepam.

Systematic review of translational insights: Neuromodulation in animal models for Diabetic Peripheral Neuropathy

Diabetic Peripheral Neuropathy (DPN) is a prevalent and debilitating complication of diabetes, affecting a significant proportion of the diabetic population. Neuromodulation, an emerging therapeutic approach, has shown promise in the management of DPN symptoms. This systematic review aims to synthesize and analyze the current advancements in neuromodulation techniques for the treatment of DPN utilizing studies with preclinical animal models. A comprehensive search was conducted across multiple databases, including PubMed, Scopus, and Web of Science. Inclusion criteria were focused on studies utilizing preclinical animal models for DPN that investigated the efficacy of various neuromodulation techniques, such as spinal cord stimulation, transcranial magnetic stimulation, and peripheral nerve stimulation. The findings suggest that neuromodulation significantly alleviated pain symptoms associated with DPN. Moreover, some studies reported improvements in nerve conduction velocity and reduction in nerve damage. The mechanisms underlying these effects appeared to involve modulation of pain pathways and enhancement of neurotrophic factors. However, the review also highlights the variability in methodology and stimulation parameters across studies, highlighting the need for standardization in future research. Additionally, while the results are promising, the translation of these findings from animal models to human clinical practice requires careful consideration. This review concludes that neuromodulation presents a potentially effective therapeutic strategy for DPN, but further research is necessary to optimize protocols and understand the underlying molecular mechanisms. It also emphasizes the importance of bridging the gap between preclinical findings and clinical applications to improve the management of DPN in diabetic patients.

A preclinical mice model of multiple sclerosis based on the toxin-induced double-site demyelination of callosal and cerebellar fibers

BACKGROUND

Multiple sclerosis (MS) is an irreversible progressive CNS pathology characterized by the loss of myelin (i.e. demyelination). The lack of myelin is followed by a progressive neurodegeneration triggering symptoms as diverse as fatigue, motor, locomotor and sensory impairments and/or bladder, cardiac and respiratory dysfunction. Even though there are more than fourteen approved treatments for reducing MS progression, there are still no cure for the disease. Thus, MS research is a very active field and therefore we count with different experimental animal models for studying mechanisms of demyelination and myelin repair, however, we still lack a preclinical MS model assembling demyelination mechanisms with relevant clinical-like signs.

RESULTS

Here, by inducing the simultaneous demyelination of both callosal and cerebellar white matter fibers by the double-site injection of lysolecithin (LPC), we were able to reproduce CNS demyelination, astrocyte recruitment and increases levels of proinflammatory cytokines levels along with motor, locomotor and urinary impairment, as well as cardiac and respiratory dysfunction, in the same animal model. Single site LPC-injections either in corpus callosum or cerebellum only, fails in to reproduce such a complete range of MS-like signs.

CONCLUSION

We here report that the double-site LPC injections treatment evoke a complex MS-like mice model. We hope that this experimental approach will help to deepen our knowledge about the mechanisms of demyelinated diseases such as MS.

Constraint-Induced Movement Therapy Promotes Myelin Remodeling and Motor Function by Mediating Sox2/Fyn Signals in Rats With Hemiplegic Cerebral Palsy

OBJECTIVE

Hypoxic-ischemic brain injury in infants often leads to hemiplegic motor dysfunction. The mechanism of their motor dysfunction has been attributed to deficiencies of the transcription factor sex-determining region (SRY) box 2 (Sox2) or the non-receptor-type tyrosine kinase Fyn (involved in neuronal signal transduction), which causes a defect in myelin formation. Constraint-induced movement therapy (CIMT) following cerebral hypoxia-ischemia may stimulate myelin growth by regulating Sox2/Fyn, Ras homolog protein family A (RhoA), and rho-associated kinase 2 (ROCK2) expression levels. This study investigated how Sox2/Fyn regulates myelin remodeling following CIMT to improve motor function in rats with hemiplegic cerebral palsy (HCP).

METHODS

To investigate the mechanism of Sox2 involvement in myelin growth and neural function in rats with HCP, Lentivirus (Lenti)-Sox2 adeno-associated virus and negative control-Lenti-Sox2 (LS) adeno-associated virus were injected into the lateral ventricle. The rats were divided into a control group and an HCP group with different interventions (CIMT, LS, or negative control-LS [NS] treatment), yielding the HCP, HCP plus CIMT (HCP + CIMT), HCP + LS, HCP + LS + CIMT, HCP + NS, and HCP + NS + CIMT groups. Front-limb suspension and RotaRod tests, Golgi-Cox staining, transmission electron microscopy, immunofluorescence staining, western blotting, and quantitative polymerase chain reaction experiments were used to analyze the motor function, dendrite/axon area, myelin ultrastructure, and levels of expression of oligodendrocytes and Sox2/Fyn/RhoA/ROCK2 in the motor cortex.

RESULTS

The rats in the HCP + LS + CIMT group had better values for motor function, dendrite/axon area, myelin ultrastructure, oligodendrocytes, and Sox2/Fyn/RhoA/ROCK2 expression in the motor cortex than rats in the HCP and HCP + NS groups. The improvement of motor function and myelin remodeling, the expression of oligodendrocytes, and the expression of Sox2/Fyn/RhoA/ROCK2 in the HCP + LS group were similar to those in the HCP + CIMT group.

CONCLUSION

CIMT might overcome RhoA/ROCK2 signaling by upregulating the transcription of Sox2 to Fyn in the brain to induce the maturation and differentiation of oligodendrocytes, thereby promoting myelin remodeling and improving motor function in rats with HCP.

IMPACT

The pathway mediated by Sox2/Fyn could be a promising therapeutic target for HCP.

Pros and cons of narrow- versus wide-compartment rotarod apparatus: An experimental study in mice

The rotarod test, a sensorimotor assessment that allows for quantitative evaluation of motor coordination in rodents, has extensive application in many research fields. The test results exhibit extreme between-study variability, sometimes making it challenging to conclude the validity of certain disease models and related therapeutic effects. Although the variation in test paradigms may account for this disparity, some features of rotarod apparatus including rod diameter make differences. However, it is unknown whether the width of animal compartment has a role in rotarod performance. Here we comprehensively evaluated the active rotarod performance and adverse incidents in multiple strains of mice on an 11-cm- or a 5-cm-wide compartment apparatus. We found that mouse behaviors on these apparatuses were surprisingly different. It took a markedly longer time to train mice on the narrow- than wide-compartment rotarod. Further, non-transgenic B6129S and tau knockout mice aged 11 months and beyond showed different levels of improvement based on the compartment width. These mice had no overt improvements on accelerating rotarod over 4-5 training sessions on the narrow compartment, contrary to marked progress on the wide counterpart. The incidents of mice passively somersaulting round and fragmented running occurred significantly more on the wide than narrow compartment during accelerating rotarod sessions. Mice fell off rod more frequently on narrow than wide compartments upon attempt to turn around and when moving backward on rod. The pros and cons of narrow versus wide compartments are informative as to how to choose a rotarod apparatus that best fits the animal models used.

Discovery of Novel Isonipecotic Acid-Based Heteroaryl Amino Acid Derivatives as Potential Anticonvulsant Agents: Design, Synthesis, In-Silico ADME Study, and Molecular Docking Studies

Background

Epilepsy is a neurological disorder characterized by anomalous brain activity, convulsions, and odd behavior. Several substituted-(naphthalen-2-yl)-3-(1H-indol-3-yl) allyl)-1,4-dihydropyridine-4-carboxylic acid derivatives (5a-j) were intended to be produced in the current research effort to reduce convulsions and seizures.

Materials and Methods

The newly developed compounds were produced by the prescribed process. Numerous methods (infrared spectroscopy (IR), nuclear magnetic resonance (NMR), mass, elemental analysis, etc.) were used to characterize these substances. Several models were used to test each of these molecules for anticonvulsant activity. By using the rotarod and ethanol potentiation techniques, neurotoxicity was also evaluated. The study meticulously examined each parameter and showed absorption, distribution, metabolism, and excretion (ADME) predictions for each of the 10 congeners that were produced. In addition, studies on molecular docking employed the gamma amino butyric acid (GABA)-A target protein.

Results

Anticonvulsant screening results identified compounds 5f, 5h, 5d, and 5b as the most efficacious of the series. All synthesized equivalents largely passed the neurotoxicity test. The results of molecular docking revealed significant interactions at the active site of GABA-A with LEU B: 99, TYR A: 62, Ala A: 174, and THR B: 202, and the outcomes were good and in agreement with in vivo findings.

Conclusions

The study's findings showed that some substances had promising anticonvulsant properties that were comparable to those of the standard drug. The highly active novel anticonvulsant analogs may therefore represent a possible lead, and additional studies may result in a potential new drug candidate.