Protocol paper: kainic acid excitotoxicity-induced spinal cord injury paraplegia in Sprague-Dawley rats

Advanced neuroprosthetic electrode design optimized by electromagnetic finite element simulation: innovations and applications

Based on electrophysiological activity, neuroprostheses can effectively monitor and control neural activity. Currently, electrophysiological neuroprostheses are widely utilized in treating neurological disorders, particularly in restoring motor, visual, auditory, and somatosensory functions after nervous system injuries. They also help alleviate inflammation, regulate blood pressure, provide analgesia, and treat conditions such as epilepsy and Alzheimer's disease, offering significant research, economic, and social value. Enhancing the targeting capabilities of neuroprostheses remains a key objective for researchers. Modeling and simulation techniques facilitate the theoretical analysis of interactions between neuroprostheses and the nervous system, allowing for quantitative assessments of targeting efficiency. Throughout the development of neuroprostheses, these modeling and simulation methods can save time, materials, and labor costs, thereby accelerating the rapid development of highly targeted neuroprostheses. This article introduces the fundamental principles of neuroprosthesis simulation technology and reviews how various simulation techniques assist in the design and performance enhancement of neuroprostheses. Finally, it discusses the limitations of modeling and simulation and outlines future directions for utilizing these approaches to guide neuroprosthesis design.

Animal models of neuropathic pain

Animal models continue to be crucial to developing our understanding of the molecular, cellular, and neurophysiological mechanisms that lead to neuropathic pain. The overwhelming majority of animal studies use rodent models, ranging from surgical and trauma-induced models to those induced by metabolic diseases, genetic mutations, viruses, neurotoxic drugs, and cancer. We discuss the clinical relevance of the available models and the pain behavior tests commonly used as outcome measures. Finally, we summarize the refinements that have been proposed to improve the ability of animal model studies to predict clinical efficacy.

Excitotoxic spinal damage induced by kainic acid impairs locomotion, alters nociception, and reduces CREB nuclear translocation

Our previous in vitro studies showed that excitotoxicity evoked by glutamate analogue kainate (KA) significantly decreased the number of rat spinal neurons and triggered high release of glutamate leading to locomotor network block. Our current objective was to assess the role of CREB as a predictive marker of damage following chemically-induced spinal cord injury by using in vivo and in vitro models. Thus, in vivo excitotoxicity in Balb/c adult mice was induced by KA intraspinal injection, while in vitro spinal cord excitotoxicity was produced by bath-applied KA. KA application evoked significant neuronal loss, deterioration in hindlimb motor coordination and thermal allodynia. In addition, immunohistochemical analysis showed that KA application resulted in decreased number of CREB positive nuclei in the ventral horn and in dorsal layers III-IV. Our data suggests that excitotoxic-induced neuronal loss may be potentially predicted by altered CREB nuclear translocation.

NeuroAiDTM-II (MLC901) Promoted Neurogenesis by Activating the PI3K/AKT/GSK-3β Signaling Pathway in Rat Spinal Cord Injury Models

Traumatic damage to the spinal cord (SCI) frequently leads to irreversible neurological deficits, which may be related to apoptotic neurodegeneration in nerve tissue. The MLC901 treatment possesses neuroprotective and neuroregenerative activity. This study aimed to explore the regenerative potential of MLC901 and the molecular mechanisms promoting neurogenesis and functional recovery after SCI in rats. A calibrated forceps compression injury for 15 s was used to induce SCI in rats, followed by an examination of the impacts of MLC901 on functional recovery. The Basso, Beattie, and Bresnahan (BBB) scores were utilized to assess neuronal functional recovery; H&E and immunohistochemistry (IHC) staining were also used to observe pathological changes in the lesion area. Somatosensory Evoked Potentials (SEPs) were measured using the Nicolet® Viking Quest™ apparatus. Additionally, we employed the Western blot assay to identify PI3K/AKT/GSK-3β pathway-related proteins and to assess the levels of GAP-43 and GFAP through immunohistochemistry staining. The study findings revealed that MLC901 improved hind-limb motor function recovery, alleviating the pathological damage induced by SCI. Moreover, MLC901 significantly enhanced locomotor activity, SEPs waveform, latency, amplitude, and nerve conduction velocity. The treatment also promoted GAP-43 expression and reduced reactive astrocytes (GFAP). MLC901 treatment activated p-AKT reduced p-GSK-3β expression levels and showed a normalized ratio (fold changes) relative to β-tubulin. Specifically, p-AKT exhibited a 4-fold increase, while p-GSK-3β showed a 2-fold decrease in T rats compared to UT rats. In conclusion, these results suggest that the treatment mitigates pathological tissue damage and effectively improves neural functional recovery following SCI, primarily by alleviating apoptosis and promoting neurogenesis. The underlying molecular mechanism of this treatment mainly involves the activation of the PI3K/AKT/GSK-3β pathway.

Resveratrol evokes neuroprotective effects and improves foot stance following kainate-induced excitotoxic damage to the mouse spinal cord

Excitotoxicity, characterized by over-activation of glutamate receptors, is a major contributor to spinal cord injury (SCI) pathophysiology, resulting in neuronal death and loss of locomotor function. In our previous in vitro studies, we showed that excitotoxicity induced by the glutamate analogue kainate (KA) leads to a significant reduction in the number of neurons, providing a model for SCI. Our current objective was to assess the neuroprotective role of resveratrol (RESV), a natural polyphenol, following KA-induced SCI. In vivo excitotoxicity was induced by intraspinal injection of KA immediately followed by RESV administration to Balb/C adult male mice. In neonatal mouse spinal cord preparations, excitotoxicity was transiently induced by bath-applied KA, either with or without RESV. KA administration resulted in a significant deterioration in hindlimb motor coordination and balance during locomotion, which was partially reverted by RESV. Additionally, RESV preserved neurons in both dorsal and ventral regions. Sirtuin 2 (SIRT2) immunoreactive signal was increased by RESV, while the selective SIRT1 inhibitor 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide (EX-527) attenuated RESV neuroprotective effects. These findings suggest that RESV attenuation of excitotoxic-induced neuronal loss and locomotor deficits is mediated, at least in part, through the activation of SIRT1, potentially involving SIRT2 as well. Indeed, our results highlight the potential use of RESV to enhance neuroprotective strategies for SCI.