SNAP25 ameliorates sensory deficit in rats with spinal cord transection

Neuroprotection of celastrol against postoperative cognitive dysfunction through dampening cGAS-STING signaling

Neuroinflammation is a central player in postoperative cognitive dysfunction (POCD), an intractable and highly confounding neurological complication with finite therapeutic options. Celastrol, a quinone methide triterpenoid, is a bioactive ingredient extracted from Tripterygium wilfordii with talented anti-inflammatory capacity. However, it is unclear whether celastrol can prevent anesthesia/surgery-evoked cognitive deficits in an inflammation-specific manner. The STING agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was used to determine whether celastrol possesses neuroprotection dependent on the STING pathway in vivo and in vitro. Isoflurane and laparotomy triggered cGAS-STING activation, caspase-3/GSDME-dependent pyroptosis, and enhanced Iba-1 immunoreactivity. Celastrol improved cognitive performance and decreased the levels of cGAS, 2'3'-cGAMP, STING, NF-κB phosphorylation, Iba-1, TNF-α, IL-6, and IFN-β. Downregulation of cleaved caspase-3 and N-GSDME was observed in the hippocampus of POCD mice and HT22 cells after celastrol administration, accompanied by limited secretion of pyroptosis-pertinent pro-inflammatory cytokines IL-1β and IL-18. DMXAA neutralized the favorable influences of celastrol on cognitive function, as confirmed by the activation of the STING/caspase-3/GSDME axis. These findings implicate celastrol as a therapeutic agent for POCD through anti-inflammation and anti-pyroptosis.

Neurotrophic and synaptic effects of GnRH and/or GH upon motor function after spinal cord injury in rats

Thoracic spinal cord injury (SCI) profoundly impairs motor and sensory functions, significantly reducing life quality without currently available effective treatments for neuroprotection or full functional regeneration. This study investigated the neurotrophic and synaptic recovery potential of gonadotropin-releasing hormone (GnRH) and growth hormone (GH) treatments in ovariectomized rats subjected to thoracic SCI. Employing a multidisciplinary approach, we evaluated the effects of these hormones upon gene expression of classical neurotrophins (NGF, BDNF, and NT3) as well as indicative markers of synaptic function (Nlgn1, Nxn1, SNAP25, SYP, and syntaxin-1), together with morphological assessments of myelin sheath integrity (Klüver-Barrera staining and MBP immunoreactivity) and synaptogenic proteins (PSD95, SYP) by immunohystochemistry (IHC) , and also on the neuromotor functional recovery of hindlimbs in the lesioned animals. Results demonstrated that chronic administration of GnRH and GH induced notable upregulation in the expression of several neurotrophic and synaptogenic activity genes. Additionally, the treatment showed a significant impact on the restoration of functional synaptic markers and myelin integrity. Intriguingly, while individual GnRH application induced certain recovery benefits, the combined treatment with GH appeared to inhibit neuromotor recovery, suggesting a complex interplay in hormonal regulation post-SCI. GnRH and GH are bioactive and participate in modulating neurotrophic responses and synaptic restoration under neural damage conditions, offering insights into novel therapeutic approaches for SCI. However, the intricate effects of combined hormonal treatment accentuate the necessity for further investigation that conduce to optimal and novel therapeutic strategies for patients with spinal cord lesions.

Neuronal-specific TNFAIP1 ablation attenuates postoperative cognitive dysfunction via targeting SNAP25 for K48-linked ubiquitination

BACKGROUND

Synaptosomal-associated protein 25 (SNAP25) exerts protective effects against postoperative cognitive dysfunction (POCD) by promoting PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy and repressing caspase-3/gasdermin E (GSDME)-mediated pyroptosis. However, the regulatory mechanisms of SNAP25 protein remain unclear.

METHODS

We employed recombinant adeno-associated virus 9 (AAV9)-hSyn to knockdown tumor necrosis factor α-induced protein 1 (TNFAIP1) or SNAP25 and investigate the role of TNFAIP1 in POCD. Cognitive performance, hippocampal injury, mitophagy, and pyroptosis were assessed. Co-immunoprecipitation (co-IP) and ubiquitination assays were conducted to elucidate the mechanisms by which TNFAIP1 stabilizes SNAP25.

RESULTS

Our results demonstrated that the ubiquitin ligase TNFAIP1 was upregulated in the hippocampus of mice following isoflurane (Iso) anesthesia and laparotomy. The N-terminal region (residues 1-96) of TNFAIP1 formed a conjugate with SNAP25, leading to lysine (K) 48-linked polyubiquitination of SNAP25 at K69. Silencing TNFAIP1 enhanced SH-SY5Y cell viability and conferred antioxidant, pro-mitophagy, and anti-pyroptosis properties in response to Iso and lipopolysaccharide (LPS) challenges. Conversely, TNFAIP1 overexpression reduced HT22 cell viability, increased reactive oxygen species (ROS) accumulation, impaired PINK1/Parkin-dependent mitophagy, and induced caspase-3/GSDME-dependent pyroptosis by suppressing SNAP25 expression. Neuron-specific knockdown of TNFAIP1 ameliorated POCD, restored mitophagy, and reduced pyroptosis, which was reversed by SNAP25 depletion.

CONCLUSIONS

In summary, our findings demonstrated that inhibiting TNFAIP1-mediated degradation of SNAP25 might be a promising therapeutic approach for mitigating postoperative cognitive decline. Video Abstract.

Effects of the SNAP-25 Mnll variant on hippocampal functional connectivity in children with attention deficit/hyperactivity disorder

Objectives

Attention-deficit/hyperactivity disorder (ADHD) is one of the most widespread and highly heritable neurodevelopmental disorders affecting children worldwide. Although synaptosomal-associated protein 25 (SNAP-25) is a possible gene hypothesized to be associated with working memory deficits in ADHD, little is known about its specific impact on the hippocampus. The goal of the current study was to determine how variations in ADHD's SNAP-25 Mnll polymorphism (rs3746544) affect hippocampal functional connectivity (FC).

Methods

A total of 88 boys between the ages of 7 and 10 years were recruited for the study, including 60 patients with ADHD and 28 healthy controls (HCs). Data from resting-state functional magnetic resonance imaging (rs-fMRI) and clinical information were acquired and assessed. Two single nucleotide polymorphisms (SNP) in the SNAP-25 gene were genotyped, according to which the study's findings separated ADHD patients into two groups: TT homozygotes (TT = 35) and G-allele carriers (TG = 25).

Results

Based on the rs-fMRI data, the FC of the right hippocampus and left frontal gyrus was evaluated using group-based comparisons. The corresponding sensitivities and specificities were assessed. Following comparisons between the patient groups, different hippocampal FCs were identified. When compared to TT patients, children with TG had a lower FC between the right precuneus and the right hippocampus, and a higher FC between the right hippocampus and the left middle frontal gyrus.

Conclusion

The fundamental neurological pathways connecting the SNAP-25 Mnll polymorphism with ADHD via the FC of the hippocampus were newly revealed in this study. As a result, the hippocampal FC may further serve as an imaging biomarker for ADHD.

Inhibition of PINK1-Mediated Mitophagy Contributes to Postoperative Cognitive Dysfunction through Activation of Caspase-3/GSDME-Dependent Pyroptosis

PTEN-induced kinase 1 (PINK1)-mediated mitophagy and caspase-1/gasdermin D canonical pyroptosis pathways have been implicated in the pathogenesis of postoperative cognitive dysfunction (POCD). However, gasdermin E (GSDME), another recently identified executioner of pyroptosis that can be specifically cleaved by caspase-3, is highly expressed in the brain and neurons. This study aimed to ascertain whether PINK1-dependent mitophagy governs postoperative cognitive capacity through caspase-3/GSDME. Twelve month old male Sprague-Dawley rats underwent exploratory laparotomy under isoflurane anesthesia. Lipopolysaccharide (LPS)-primed SH-SY5Y cells were used to mimic postsurgical neuroinflammation. For the interventional study, rats were administered with adeno-associated virus serotype 9 (AAV9)-mediated silencing of Pink1 and/or caspase-3 inhibitor Ac-DEVD-CHO (Ac-DC). SH-SY5Y cells were treated with siPINK1 and/or Ac-DC. Cognitive performance was assessed using the Morris water maze test. The mitophagy- and pyroptosis-related parameters were determined in the hippocampus and SH-SY5Y cells. Anesthesia/surgery and LPS caused defective PINK1-mediated mitophagy and activation of caspase-3/GSDME-dependent pyroptosis. AAV-9 mediated Pink1 overexpression mitigated cognitive impairment and caspase-3/GSDME-dependent pyroptosis. Conversely, inhibition of PINK1 aggravates POCD and overactivates neuronal pyroptosis. These abnormalities were rescued by Ac-DC treatment. Collectively, PINK1-mediated mitophagy regulates anesthesia and surgery-induced cognitive impairment by negatively affecting the caspase-3/GSDME pyroptosis pathway, which provides a promising therapeutic target for POCD.

Synaptic Cell Adhesion Molecule 3 (SynCAM3) Deletion Promotes Recovery from Spinal Cord Injury by Limiting Glial Scar Formation

Synaptic cell adhesion molecules (SynCAMs) play an important role in the formation and maintenance of synapses and the regulation of synaptic plasticity. SynCAM3 is expressed in the synaptic cleft of the central nervous system (CNS) and is involved in the connection between axons and astrocytes. We hypothesized that SynCAM3 may be related to the astrocytic scar (glial scar, the most important factor of CNS injury treatment) through extracellular matrix (ECM) reconstitution. Thus, we investigated the influence of the selective removal of SynCAM3 on the outcomes of spinal cord injury (SCI). SynCAM3 knock-out (KO) mice were subjected to moderate compression injury of the lower thoracic spinal cord using wild-type (WT) (C57BL/6JJc1) mice as controls. Single-cell RNA sequencing analysis over time, quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and immunohistochemistry (IHC) showed reduced scar formation in SynCAM3 KO mice compared to WT mice. SynCAM3 KO mice showed improved functional recovery from SCI by preventing the transformation of reactive astrocytes into scar-forming astrocytes, resulting in improved ECM reconstitution at four weeks after injury. Our findings suggest that SynCAM3 could be a novel therapeutic target for SCI.

Conversion of Neural Stem Cells into Functional Neuron-Like Cells by MicroRNA-218: Differential Expression of Functionality Genes

Conversion of mesenchymal stem cells (MSC) into neuron-like cells (NLC) is a feasible cell therapy strategy for replacing lost neurons in neuronal disorders. In this study, adipose-derived MSC (ADMSC) were converted into neural stem cells (NSC) via neurosphere. The resulting NSC were then differentiated into NLC by transduction with microRNA-218, using a lentiviral vector. ADMSC, NSC, and NLC were first characterized by flow cytometry, RT-PCR, and immunocytochemistry. The functionality of the NLC was evaluated by qRT-PCR and patch clamp recording. Immunophenotyping of ADMSC showed their immunoreactivity to MSC markers CD90, CD73, CD105, and CD49d, but not to CD31 and CD45. RT-PCR results demonstrated the expression of nestin, neurogenin, neurod1, neurofilament light, and GAP43 genes in NSC while NLC expressed synaptophysin, neurofilament heavy, and GAP43. In addition, NSC morphology changed into multipolar with long processes after transduction with miR-218. Moreover, using qRT-PCR, the expression levels of miR-218 and functionality genes CACNA1C, SNAP25, KCNH1, KCNMA1, and SCN9A were significantly increased in NLC, compared with NSC, and ADMSC at 3 weeks and 5 months post-transduction. Furthermore, the generated NLC expressed significantly higher protein levels of neurofilament heavy polypeptide (NFh) and enolase 2 (Eno2) neuronal markers, compared with ADMSC and NSC. Finally, action potentials were successfully recorded by the generated NLC, using patch clamp. In summary, ADMSC-derived NSC differentiated into functional NLC by transduction with miR-218. The generated NLC expressed functional SNAP25, CACNA1C, KCNH1, KCNMA1, and SCN9A and produced an action potential, which provides useful insights into the generation of functional neuronal cells.

Spinal SNAP-25 regulates membrane trafficking of GluA1-containing AMPA receptors in spinal injury-induced neuropathic pain in rats

INTRODUCTION

Synaptosomal associated proteins of 25 kDa (SNAP-25), as a member of stable soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex, is critical for membrane fusion and required for the release of neurotransmitters. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor is implicated in pathologic pain. This study aimed to investigate whether and how SNAP-25 regulated AMPA receptors in neuropathic pain.

METHODS

Male Sprague-Dawley rats underwent L₄ spinal nerve ligation (SNL) or the sham procedure. After assessing mechanical allodynia and thermal sensitivity, the ipsilateral portion of the L_4-5 spinal cord was harvested. The expression level of SNAP-25 was analyzed by Western blot analysis and real-time quantitative polymerase chain reaction. SNAP-25 phosphorylation and AMPA receptor membrane trafficking levels were evaluated with Western blot analysis. An association between SNAP-25 and AMPA membrane trafficking was confirmed by SNAP-25 expression or phosphorylation inhibition.

RESULTS

The SNL procedure induced and maintained mechanical allodynia and thermal hyperalgesia. SNL increased the expression and phosphorylation of SNAP-25 and the membrane trafficking of AMPA receptors in the spinal cord. SNAP-25 expression or phosphorylation inhibition alleviated neuropathic pain and downregulated membrane trafficking of AMPA receptors after SNL. GluA1-containing AMPA receptor inhibition relieved mechanical allodynia and thermal hyperalgesia after SNL.

CONCLUSIONS

The upregulation of SNAP-25-dependent membrane trafficking of AMPA receptors via SNAP-25 phosphorylation at Ser187 contributed to SNL-induced neuropathic pain. Thus, the inhibition of SNAP-25 expression or phosphorylation might serve as a treatment for neuropathic pain. However, the mechanism of GluA1-containing AMPA receptor membrane trafficking mediated by SNAP-25 phosphorylation in neuropathic pain deserves further exploration.

miR-22-3p enhances the intrinsic regenerative abilities of primary sensory neurons via the CBL/p-EGFR/p-STAT3/GAP43/p-GAP43 axis

Spinal cord injury (SCI) is a devastating disease. Strategies that enhance the intrinsic regenerative ability are very important for the recovery of SCI to radically prevent the occurrence of sensory disorders. Epidermal growth factor (EGF) showed a limited effect on the growth of primary sensory neuron neurites due to the degradation of phosphorylated-epidermal growth factor receptor (p-EGFR) in a manner dependent on Casitas B-lineage lymphoma (CBL) (an E3 ubiquitin-protein ligase). MiR-22-3p predicted from four databases could target CBL to inhibit the expression of CBL, increase p-EGFR levels and neurites length via STAT3/GAP43 pathway rather than Erk1/2 axis. EGF, EGFR, and miR-22-3p were downregulated sharply after injury. In vivo miR-22-3p Agomir application could regulate CBL/p-EGFR/p-STAT3/GAP43/p-GAP43 axis, and restore spinal cord sensory conductive function. This study clarified the mechanism of the limited promotion effect of EGF on adult primary sensory neuron neurite and targeting miR-22-3p could be a novel strategy to treat sensory dysfunction after SCI.

miR-155-5p Promotes Dorsal Root Ganglion Neuron Axonal Growth in an Inhibitory Microenvironment via the cAMP/PKA Pathway

Sensory dysfunction post spinal cord injury causes patients great distress. Sciatic nerve conditioning injury (SNCI) has been shown to restore sensory function after spinal cord dorsal column injury (SDCL); however, the underlying mechanism of this recovery remains unclear. We performed a microarray assay to determine the associated miRNAs that might regulate the process of SNCI promoting SDCL repair. In total, 13 miRNAs were identified according to our inclusion criteria, and RT-qPCR was used to verify the microarray results. Among the 13 miRNAs, the miR-155-5p levels were decreased at 9 h, 3 d, 7 d, 14 d, 28 d, 2 m and 3 m timepoints in the SDCL group, while the SNCI group had a smaller decrease. Thus, miR-155-5p was chosen for further study after a literature review and an analysis with the TargetScan online tool. Specifically, miR-155-5p targets PKI-α, and the expression pattern of PKI-α was opposite that of miR-155-5p in both the SDCL and SNCI groups. Interestingly, miR-155-5p could promote dorsal root ganglion (DRG) neuron axon growth via the cAMP/PKA pathway and in a TNF-α, IL-1β or MAG inhibitory microenvironment in vitro. Furthermore, miR-155-5p could regulate the cAMP/PKA pathway and promote sensory conduction function recovery post dorsal column injury as detected by NF-200 immunohistochemistry, somatosensory-evoked potentials, BBB scale and tape removal test. Collectively, our results demonstrated that miR-155-5p participates in the molecular mechanism by which SNCI promotes the repair of SDCL and that upregulated miR-155-5p can repair SDCL by enhancing DRG neuron axon growth via the cAMP/PKA pathway. These findings suggest a novel treatment target for spinal cord injury.

Sorafenib promotes sensory conduction function recovery via miR-142-3p/AC9/cAMP axis post dorsal column injury

Spinal cord injury results in sensation dysfunction. This study explored miR-142-3p, which acts a critical role in sciatic nerve conditioning injury (SNCI) promoting the repair of the dorsal column injury and validated its function on primary sensory neuron(DRG). miR-142-3p expression increased greatly in the spinal cord dorsal column lesion (SDCL) group and increased slightly in the SNCI group. Subsequently, the expression of adenylate cyclase 9 (AC9), the target gene of miR-142-3p, declined sharply in the SDCL group and declined limitedly in the SNCI group. The expression trend of cAMP was opposite to that of miR-142-3p. MiR-142-3p inhibitor improved the axon length, upregulated the expression of AC9, cAMP, p-CREB, IL-6, and GAP43, and downregulated the expression of GTP-RhoA. miR-142-3p inhibitor combined with AC9 siRNA showed shorter axon length, the expression of AC9, cAMP, p-CREB, IL-6, and GAP43 was decreased, and the expression of GTP-RhoA was increased. H89 and AG490, inhibitors of cAMP/PKA pathway and IL6/STAT3/GAP43 axis, respectively, declined the enhanced axonal growth by miR-142-3p inhibitor and altered the expression level of the corresponding proteins. Thus, a substitution therapy using Sorafenib that downregulates the miR-142-3p expression for SNCI was investigated. The results showed the effect of Sorafenib was similar to that of miR-142-3p inhibitor and SNCI on both axon growth in vitro and sensory conduction function recovery in vivo. In conclusion, miR-142-3p acts a pivotal role in SNCI promoting the repair of dorsal column injury. Sorafenib mimics the treatment effect of SNCI via downregulation of miR-142-3p, subsequently, promoting sensory conduction function recovery post dorsal column injury.

MiR-20a Plays a Key Regulatory Role in the Repair of Spinal Cord Dorsal Column Lesion via PDZ-RhoGEF/RhoA/GAP43 Axis in Rat

Spinal cord injury (SCI) causes sensory dysfunctions such as paresthesia, dysesthesia, and chronic neuropathic pain. MiR-20a facilitates the axonal outgrowth of the cortical neurons. However, the role of miR-20a in the axonal outgrowth of primary sensory neurons and spinal cord dorsal column lesion (SDCL) is yet unknown. Therefore, the role of miR-20a post-SDCL was investigated in rat. The NF-200 immunofluorescence staining was applied to observe whether axonal outgrowth of dorsal root ganglion (DRG) neurons could be altered by miR-20a or PDZ-RhoGEF modulation in vitro. The expression of miR-20a was quantized with RT-PCR. Western blotting analyzed the expression of PDZ-RhoGEF/RhoA/GAP43 axis after miR-20a or PDZ-RhoGEF was modulated. The spinal cord sensory conduction function was assessed by somatosensory-evoked potentials and tape removal test. The results demonstrated that the expression of miR-20a decreased in a time-dependent manner post-SDCL. The regulation of miR-20a modulated the axonal growth and the expression of PDZ-RhoGEF/RhoA/GAP43 axis in vitro. The in vivo regulation of miR-20a altered the expression of miR-20a-PDZ-RhoGEF/RhoA/GAP43 axis and promoted the recovery of ascending sensory function post-SDCL. The results indicated that miR-20a/PDZ-RhoGEF/RhoA/GAP43 axis is associated with the pathophysiological process of SDCL. Thus, targeting the miR-20a/PDZ-RhoGEF /RhoA/GAP43 axis served as a novel strategy in promoting the sensory function recovery post-SCI.

PEITC promotes neurite growth in primary sensory neurons via the miR-17-5p/STAT3/GAP-43 axis

The present study explored a key miRNA that plays a vital role in sciatic nerve conditioning injury promoting repair of injured dorsal column, and validated its function. Microarray analysis revealed miR-17-5p expression decreased sharply at 3, 7 and 14 days in the sciatic nerve conditioning injury group compared with the simple dorsal column lesion group. After miR-17-5p inhibition in DRG neurons, GAP-43 expression was upregulated and neurite growth was increased. STAT3 together with p-STAT3 showed opposite trends with miR-17-5p. MiR-17-5p inhibition extended neurite and upregulated STAT3, p-STAT3 and GAP-43. To further determine a substitution therapy for sciatic nerve conditioning injury, beta-phenethyl isothiocyanate (PEITC), which downregulates miR-17-5p, was assessed. The results showed that treatment with 10 µM PEITC resulted in longest neurite length. Further experiments demonstrated PEITC induced neurite growth by inhibiting miR-17-5p and further upregulating STAT3, p-STAT3 and GAP-43. The somatosensory evoked potential test confirmed similar treatment effects for PEITC, Ad-miRNA-17-5p inhibitor, and sciatic nerve conditioning injury on the dorsal column lesion. In conclusion, the miR-17-5p/STAT3/GAP-43 axis is an indispensable component of sciatic nerve conditioning injury promoting repair of injured dorsal column. PEITC could promote repair of injured dorsal column via the miR-17-5p/STAT3/GAP-43 axis, and could mimic the treatment effect of sciatic nerve conditioning injury.

SNARE proteins in membrane trafficking

SNAREs are the core machinery mediating membrane fusion. In this review, we provide an update on the recent progress on SNAREs regulating membrane fusion events, especially the more detailed fusion processes dissected by well-developed biophysical methods and in vitro single molecule analysis approaches. We also briefly summarize the relevant research from Chinese laboratories and highlight the significant contributions on our understanding of SNARE-mediated membrane trafficking from scientists in China.

Maternal Rest/Nrsf Regulates Zebrafish Behavior through snap25a/b

During embryonic development, regulation of gene expression is key to creating the many subtypes of cells that an organism needs throughout its lifetime. Recent work has shown that maternal genetics and environmental factors have lifelong consequences on diverse processes ranging from immune function to stress responses. The RE1-silencing transcription factor (Rest) is a transcriptional repressor that interacts with chromatin-modifying complexes to repress transcription of neural-specific genes during early development. Here we show that in zebrafish, maternally supplied rest regulates expression of target genes during larval development and has lifelong impacts on behavior. Larvae deprived of maternal rest are hyperactive and show atypical spatial preferences. Adult male fish deprived of maternal rest present with atypical spatial preferences in a novel environment assay. Transcriptome sequencing revealed 158 genes that are repressed by maternal rest in blastula stage embryos. Furthermore, we found that maternal rest is required for target gene repression until at least 6 dpf. Importantly, disruption of the RE1 sites in either snap25a or snap25b resulted in behaviors that recapitulate the hyperactivity phenotype caused by absence of maternal rest Both maternal rest mutants and snap25a RE1 site mutants have altered primary motor neuron architecture that may account for the enhanced locomotor activity. These results demonstrate that maternal rest represses snap25a/b to modulate larval behavior and that early Rest activity has lifelong behavioral impacts.

SIGNIFICANCE STATEMENT

Maternal factors deposited in the oocyte have well-established roles during embryonic development. We show that, in zebrafish, maternal rest (RE1-silencing transcription factor) regulates expression of target genes during larval development and has lifelong impacts on behavior. The Rest transcriptional repressor interacts with chromatin-modifying complexes to limit transcription of neural genes. We identify several synaptic genes that are repressed by maternal Rest and demonstrate that snap25a/b are key targets of maternal rest that modulate larval locomotor activity. These results reveal that zygotic rest is unable to compensate for deficits in maternally supplied rest and uncovers novel temporal requirements for Rest activity, which has implications for the broad roles of Rest-mediated repression during neural development and in disease states.

Synaptosomal-associated protein 25 may be an intervention target for improving sensory and locomotor functions after spinal cord contusion

Synaptosomal-associated protein 25 kDa (SNAP-25) is localized on the synapse and participates in exocytosis and neurotransmitter release. Decreased expression of SNAP-25 is associated with Alzheimer's disease and attention deficit/hyperactivity disorder. However, the expression of SNAP-25 in spinal cord contusion injury is still unclear. We hypothesized that SNAP-25 is associated with sensory and locomotor functions after spinal cord injury. We established rat models of spinal cord contusion injury to detect gene changes with a gene array. A decreased level of SNAP-25 was detected by quantitative real time-polymerase chain reaction and western blot assay at 1, 3, 7, 14 and 28 days post injury. SNAP-25 was localized in the cytoplasm of neurons of the anterior and posterior horns, which are involved in locomotor and sensory functions. Our data suggest that reduced levels of SNAP-25 are associated with sensory and locomotor functions in rats with spinal cord contusion injury.

Knockdown of α-synuclein in cerebral cortex improves neural behavior associated with apoptotic inhibition and neurotrophin expression in spinal cord transected rats

Spinal cord injury (SCI) often causes severe functional impairment with poor recovery. The treatment, however, is far from satisfaction, and the mechanisms remain unclear. By using proteomics and western blot, we found spinal cord transection (SCT) resulted in a significant down-regulation of α-synuclein (SNCA) in the motor cortex of SCT rats at 3 days post-operation. In order to detect the role of SNCA, we used SNCA-ORF/shRNA lentivirus to upregulate or knockdown SNCA expression. In vivo, SNCA-shRNA lentivirus injection into the cerebral cortex motor area not only inhibited SNCA expression, but also significantly enhanced neurons' survival, and attenuated neuronal apoptosis, as well as promoted motor and sensory function recovery in hind limbs. While, overexpression SNCA exhibited the opposite effects. In vitro, cortical neurons transfected with SNCA-shRNA lentivirus gave rise to an optimal neuronal survival and neurite outgrowth, while it was accompanied by reverse efficiency in SNCA-ORF group. In molecular level, SNCA silence induced the upregulation of Bcl-2 and the downregulation of Bax, and the expression of NGF, BDNF and NT3 was substantially upregulated in cortical neurons. Together, endogenous SNCA play a crucial role in motor and sensory function regulation, in which, the underlying mechanism may be linked to the regulation of apoptosis associated with apoptotic gene (Bax, Bcl2) and neurotrophic factors expression (NGF, BDNF and NT3). These finds provide novel insights to understand the role of SNCA in cerebral cortex after SCT, and it may be as a novel treatment target for SCI repair in future clinic trials.

Abnormal feeding behaviour in spinalised rats is mediated by hypothalamus: Restorative effect of exposure to extremely low frequency magnetic field

STUDY DESIGN

Experimental study.

OBJECTIVES

To investigate the role of hypothalamus in abnormal feeding behaviour after spinal cord injury (SCI) and the effect of exposure to extremely low frequency magnetic field (ELF-MF) on it.

SETTING

India.

METHODS

Male Wistar rats (n=44) were divided into Sham (laminectomy), SCI (complete transection of T13 spinal cord), SCI+MF (ELF-MF exposure to SCI rats), VMHL (lesion of ventromedial hypothalamus; VMH), SCI+VMHL (VMHL after SCI) and SCI+VMHL+MF (ELF-MF exposure to SCI+VMHL rats) groups. Food intake (FI), water intake (WI), calorie intake (CI), body weight (BWT), taste preference and sucrose-induced biphasic (SIB) response to noxious stimulus were studied pre and post surgery. Neuronal activity at VMH was assessed by c-Fos immunohistochemistry. The extent of neuronal degeneration and regeneration in spinal cord was assessed microscopically.

RESULTS

Data revealed post-SCI decrease in FI, WI, CI and BWT, preference for sodium chloride and citric acid, prolonged analgesic phase of SIB and increased c-Fos immunoreactivity in VMH of SCI rats vs Sham rats. VMH lesion increased FI, WI, CI, BW, preference for sweet tastants and abolished SIB, whereas in SCI+VMHL rats it abolished the effects of SCI on these parameters indicating probable involvement of VMH in SCI-induced alteration in feeding behaviour. Exposure to MF improved the study parameters in SCI rats and reduced the c-Fos immunoreactivity in VMH besides reduction in lesion volume, greater myelination and neuronal regeneration at SCI site.

CONCLUSION

SCI influences VMH, leading to alteration in feeding behaviour, which is improved by exposure to ELF-MF.

The Association of SNAP25 Gene Polymorphisms in Attention Deficit/Hyperactivity Disorder: a Systematic Review and Meta-Analysis

Attention deficit/hyperactivity disorder (ADHD) is one of the most highly heritable psychiatric disorders in childhood. The risk gene mutation accounts for about 60 to 90 % cases. Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic plasma membrane protein which is expressed highly and specifically in the neuronal cells. A number of evidences have suggested the role of SNAP-25 in the etiology of ADHD. Notably, the animal model of coloboma mouse mutant bears a ∼2-cM deletion encompassing genes including SNAP25 and displays spontaneous hyperkinetic behavior. Previous investigators have reported association between SNPs in SNAP25 and ADHD, and controversial results were observed. In this study, we analyzed the possible association between six polymorphisms (rs3746544, rs363006, rs1051312, rs8636, rs362549, and rs362998) of SNAP25 and ADHD in a pooled sample of ten family-based studies and four case-control studies by using meta-analysis. The combined analysis results were significant only for rs3746544 (P = 0.010) with mild association (odds ratio (OR) = 1.14). And, the meta-analysis data for rs8636, rs362549, and rs362998 are the first time to be reported; however, no positive association was detected. In conclusion, we report some evidence supporting the association of SNAP25 to ADHD. Future research should emphasize genome-wide association studies in more specific subgroups and larger independent samples.

Key genes expressed in different stages of spinal cord ischemia/reperfusion injury

The temporal expression of microRNA after spinal cord ischemia/reperfusion injury is not yet fully understood. In the present study, we established a model of spinal cord ischemia in Sprague-Dawley rats by clamping the abdominal aorta for 90 minutes, before allowing reperfusion for 24 or 48 hours. A sham-operated group underwent surgery but the aorta was not clamped. The damaged spinal cord was removed for hematoxylin-eosin staining and RNA extraction. Neuronal degeneration and tissue edema were the most severe in the 24-hour reperfusion group, and milder in the 48-hour reperfusion group. RNA amplification, labeling, and hybridization were used to obtain the microRNA expression profiles of each group. Bioinformatics analysis confirmed four differentially expressed microRNAs (miR-22-3p, miR-743b-3p, miR-201-5p and miR-144-5p) and their common target genes (Tmem69 and Cxcl10). Compared with the sham group, miR-22-3p was continuously upregulated in all three ischemia groups but was highest in the group with no reperfusion, whereas miR-743b-3p, miR-201-5p and miR-144-5p were downregulated in the three ischemia groups. We have successfully identified the key genes expressed at different stages of spinal cord ischemia/reperfusion injury, which provide a reference for future investigations into the mechanism of spinal cord injury.

miR-142-3p is a Potential Therapeutic Target for Sensory Function Recovery of Spinal Cord Injury

Spinal cord injury (SCI), which is a leading cause of disability in modern society, commonly results from trauma. It has been reported that application of sciatic nerve conditioning injury plays a positive role in repairing the injury of the ascending spinal sensory pathway in laboratory animals. Because of the complexity of SCI and related ethics challenges, sciatic nerve conditioning injury cannot be applied in clinical therapy. Accordingly, it is extremely important to study its mechanism and develop replacement therapy. Based on empirical study and clinical trials, this article suggests that miR-142-3p is the key therapeutic target for repairing sensory function, based on the following evidence. Firstly, studies have reported that endogenous cAMP is the upstream regulator of 3 signal pathways that are partially involved in the mechanisms of sciatic nerve conditioning injury, promoting neurite growth. The regulated miR-142-3p can induce cAMP elevation via adenylyl cyclase 9 (AC9), which is abundant in dorsal root ganglia (DRG). Secondly, compared with gene expression regulation in the injured spinal cord, inhibition of microRNA (miRNA) in DRG is less likely to cause trauma and infection. Thirdly, evidence of miRNAs as biomarkers and therapeutic targets in many diseases has been reported. In this article we suggest, for the first time, imitating sciatic nerve conditioning injury, thereby enhancing central regeneration of primary sensory neurons via interfering with the congenerous upstream regulator AC9 of the 3 above-mentioned signal pathways. We hope to provide a new clinical treatment strategy for the recovery of sensory function in SCI patients.

Regulation of gene expression in rats with spinal cord injury based on microarray data

The present study aimed to investigate the molecular mechanisms of spinal cord injury (SCI) in rats. First, the differentially expressed genes (DGEs) were screened based on GSE45006 microarray data downloaded from Gene Expression Omnibus using the significant analysis of microarray (SAM) method. Screening was performed for DEGs which were negatively or possibly correlated with time and subsequently subjected to gene ontology (GO) functional annotation. Furthermore, pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes was also performed. In addition, a protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database. Finally, GeneCodis was used to seek transcription factors and microRNAs that are involved in the regulation of DEGs. A total of 806 DEGs were upregulated and 549 DEGs were downregulated in the rats with SCI. Cholesterol metabolism-associated genes (e.g. HMGCS1, FDFT1 and IDI1) were negatively correlated with time, while injury genes (e.g. SERPING1, C1S and RAB27A) were positively correlated with time after SCI. PCNA, MCM2, JUN and SNAP25 were the hub proteins of the PPI network. The transcription factors LEF1 and SP1 were observed to be associated with the regulation of two DEGs that were involved in the cholesterol-associated metabolism as well as injury responses. A number of microRNAs (e.g. miR210, miR-487b and miR-16) were observed to target cholesterol metabolism-associated DGEs. The hub genes PCNA, MCM2, JUN and SNAP25 presumably have critical roles in rats with SCI, and the transcription factors LEF1 and SP1 may be important for the regulation of cholesterol metabolism and injury responses following SCI.