miR-6315 silencing protects against spinal cord injury through the Smo and anti-ferroptosis pathway.

Spinal cord injury (SCI) causes permanent damage and has a high disability rate. Currently, no efficient therapeutic strategy is available for SCI. The present study investigated the mechanisms of microRNAs (miRNAs) in rats with spinal cord injury. Whole transcriptome sequencing (WTS) was used for analyzing miRNA and messenger RNA (mRNA) expression patterns in rat spinal cord tissue at different time points after SCI. Gene Ontology (GO) and KEGG pathways were analyzed to obtain crucial functional pathways. miR-6315 was the most significantly up-regulated and differentially expressed miRNA after 24 h of SCI; the expression of miR-6315 gradually decreased after 3 and 7 days of SCI. Bioinformatics analysis was conducted to predict the targeting relation of miR-6315 with Smo, and qRT-PCR and dual-luciferase reporter assays were conducted for verification. The miR-6315 silencing (miR-6315-si) adenovirus was successfully constructed. miR-6315 knockdown treatment significantly promoted functional behavioral recovery in rats post-SCI through using Basso-Beattie-Bresnahan (BBB) locomotor rating scale and the inclined plane test. The neuronal axon regeneration and neuronal migration were promoted, and cell apoptosis was attenuated in treated SCI rats and Glu-treated neurons after miR-6315 knockdown using immunofluorescence and scratch assays. We discovered that Smo and anti-ferroptosis pathway factors, xCT, GSH, and GPX4, may be involved in miR-6315-regulated SCI repair. The expression of miR-6315 was negatively correlated with Smo, xCT, GSH, and GPX4. In conclusion, miR-6315 may be a potential target in the treatment of SCI.

MicroRNA-138 Regulates Spinal Cord Development by Activating the Shh in Fetal Rats.

INTRODUCTION: Dysregulation of spinal cord development can lead to serious neuronal damage and dysfunction, causing significant health problems in newborns. MiRNA-138 appears to be crucial for proliferation, differentiation, and apoptosis of cells. However, the regulation of miRNA-138 and downstream molecules in embryonic spinal cord development remain elusive. The aim of this experiment is to determine whether overexpression of miRNA-138 or RNA interference (RNAi) can regulate the development of spinal cord in fetal rats. METHODS: Two plasmid vectors including pLenti-III-mico-GFP (miRNA-138 open reading frame [ORF]) and pLenti-III-miR-Off (miRNA-138 short hairpin) were constructed and injected into the tail vein of rats on the 14th day of pregnancy. Hematoxylin-eosin (HE) staining was used to observe the cell morphology. QRT-PCR, Western blot, and immunostaining confirmed the regulatory relationship between miRNA-138 and downstream molecules sonic hedgehog (Shh). RESULTS: Overexpression of miRNA-138 increased neuron regeneration significantly and decreased neuronal apoptosis when compared with the control. Silencing of miRNA-138 increased neuronal apoptosis and spinal cord atrophy significantly. Furthermore, miRNA-138 ORF treatment effectively increased the expression level of miRNA-138 and also upregulated the level of Shh. Comparatively, knockdown of miRNA-138 downregulated Shh levels in myelodysplastic regions. CONCLUSION: These findings indicated that miRNA-138 overexpression could protect the spinal cord development of fetal rats, and the underlying mechanisms were associated with Shh expression. The present study provides a novel strategy to promote the molecular mechanism of embryonic spinal cord development.

Peptide OM-LV20 promotes structural and functional recovery of spinal cord injury in rats.

At present, there are no satisfactory therapeutic drugs for the functional recovery of spinal cord injury (SCI). We previously identified a novel peptide (OM-LV20) that accelerated the regeneration of injured skin tissues of mice and exerts neuroprotective effects against cerebral ischemia/reperfusion injury in rats. Here, the intraperitoneal injection of OM-LV20 (1 µg/kg) markedly improved motor function recovery in the hind limbs of rats with traumatic SCI, and further enhanced spinal cord repair. Administration of OM-LV20 increased the number of surviving neuron bodies, as well as the expression levels of brain-derived neurotrophic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB). In the acute stage of SCI, OM-LV20 treatment also increased superoxide dismutase and glutathione content but decreased the levels of malonaldehyde and nitric oxide. Thus, OM-LV20 significantly promoted structural and functional recovery of SCI in adult rats by increasing neuronal survival and BDNF and TrkB expression, and thereby regulating the balance of oxidative stress. Based on our knowledge, this research is the first report on the effects of amphibian-derived peptide on the recovery of SCI and our results highlight the potential of peptide OM-LV20 administration in the acceleration of the recovery of SCI.

bFGF promotes neurological recovery from neonatal hypoxic-ischemic encephalopathy by IL-1ß signaling pathway-mediated axon regeneration.

INTRODUCTION: Neonatal hypoxia-ischemic brain damage (HIBD) can lead to serious neuron damage and dysfunction, causing a significant worldwide health problem. bFGF as a protective reagent promotes neuron repair under hypoxia/ischemia (HI). However, how bFGF and downstream molecules were regulated in HI remains elusive. METHODS: We established an in vitro HI model by culturing primary cortical neurons and treated with oxygen-glucose deprivation (OGD). We suppressed the expression of bFGF by using siRNA (small interfering RNA) interference to detect the neuronal morphological changes by immunofluorescence staining. To determine the potential mechanisms regulated by bFGF, the change of downstream molecular including IL-1ß was examined in bFGF knockdown condition. IL-1ß knockout (KO) rats were generated using CRISPR/Cas9-mediated technologies. We used an accepted rat model of HI, to assess the effect of IL-1ß deletion on disease outcomes and carried out analysis on the behavior, histological, cellular, and molecular level. RESULTS: We identified that OGD can induce endogenous expression of bFGF. Both OGD and knockdown of bFGF resulted in reduction of neuron numbers, enlarged cell body and shortened axon length. We found molecules closely related to bFGF, such as interleukin-1ß (IL-1ß). IL-1ß was up-regulated after bFGF interference under OGD conditions, suggesting complex signaling between bFGF and OGD-mediated pathways. We found HI resulted in up-regulation of IL-1ß mRNA in cortex and hippocampus. IL-1ß KO rats markedly attenuated the impairment of long-term learning and memory induced by HI. Meanwhile, IL-1ß-/- (KO, homozygous) group showed better neurite growth and less apoptosis in OGD model. Furthermore, serine/threonine protein kinase (AKT1) mRNA and protein expression was significantly up-regulated in IL-1ß KO rats. CONCLUSIONS: We showed that IL-1ß-mediated axon regeneration underlie the mechanism of bFGF for the treatment of HIBD in neonatal rats. Results from this study would provide insights and molecular basis for future therapeutics in treating HIBD.

Endogenous TGFß1 Plays a Crucial Role in Functional Recovery After Traumatic Brain Injury Associated with Smad3 Signal in Rats.

Transforming growth factor-ß 1 (TGFß1) has a diverse role in astrogliosis and neuronal survival, but the underlying mechanism remains to be elucidated, especially in traumatic brain injury (TBI). Here, we show that the expression of TGFß1 was increased in the pericontusional region, accompanied with astrogliosis and neuronal loss in TBI rats. Moreover, TGFß1 knockdown not only reduced the number of neurons and inhibited astrogliosis but also resulted in a significant neurological dysfunction in rats with TBI. Subsequently, Smad3, a key downstream signal of TGFß1, was involved in pericontusional region after TBI. These findings therefore indicate that TGFß1 is involved in neuroprotection and astrogliosis, via activation of down stream Smad3 signal in the brain after injury.

Transplantation of olfactory ensheathing cells promotes the recovery of neurological functions in rats with traumatic brain injury associated with downregulation of Bad.

BACKGROUND AIMS: The neuroprotective effects of olfactory ensheathing cells (OECs) after transplantation have largely been known in the injured nervous system. However, the underlying mechanisms still must be further elucidated. We explored the effects of OEC transplantation on the recovery of neurophysiologic function and the related anti-apoptosis mechanism in acute traumatic brain injury. METHODS: The OECs from neonatal Sprague-Dawley rats were isolated, identified and labeled and then were immediately transplanted into the regions surrounding the injured brain site that is resulted from free-weight drop injury. RESULTS: Nerve growth factor and it's recepor, p75 was expressed in cultured OECs. Transplanted OECs survived, migrated around the injury site and significantly improved the neurological severe scores compared with the control group (P < 0.05). OEC transplantation significantly increased the number of GAP-43-immunopositive fibers and synaptophysin-positive vesicles (P < 0.05) but significantly decreased the number of apoptotic cells (P < 0.05). On the molecular level, the expression of Bad in the OEC transplantation group was significantly downregulated (P < 0.05). CONCLUSIONS: OEC transplantation could effectively improve neurological deficits in TBI rats; the underlying mechanism may be related with their effects on neuroprotection and regeneration induction, which is associated with the downregulation of the apoptotic molecule Bad.

BDNF expression with functional improvement in transected spinal cord treated with neural stem cells in adult rats.

Neural stem cells (NSC) could promote the repair after spinal cord transection (SCT), the underlying mechanism, however, still keeps to be defined. This study reported that NSC grafts significantly improved sensory and locomotor functions in adult rats with SCT in acute stage after injury. NSC could survive; differentiate towards neurons or glia lineage in vitro and vivo. Biotin dextran amine (BDA) tracing showed that little CST regeneration in the injury site, while SEP was recorded in NSC engrafted rats. Immunohistochemistry and Real time PCR confirmed that engrafted NSC expressed BDNF and increased the level of BDNF mRNA in injured site following transplantation. The present data therefore suggested that the functional recovery following SCT with NSC transplantation was correlated with the expression of BDNF, indicating the usage of BDNF with NSC transplantation in the treatment of SCI following injury.

Spatiotemporal changes of NGF, BDNF and NT-3 in the developing spinal cords of embryonic chicken.

Spatiotemporal changes of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in the spinal cords of chick embryonic stage day 7 (E7) and day 14 (E14) were examined by using immunohistochemistry and Western blot. Intensive NGF immunoreaction (IR) was detected in the white matter of the spinal cords, while BDNF-IR in perikaryon and neurite, and NT-3-IR in the nucleus and cytoplasm were seen in the neurons of the ventral horn in the gray matter. Comparatively, the expressions for three growth factors have expanded largely into the dorsal horn at E14, and the level of proteins for these growth factors increased significantly in the spinal cords from E7 to E14. Morphological observation showed that the lumbar spinal cords of E7 appeared rectangular, whereas it gave a butterfly shape in the gray matter consisting of the typical ventral horn, dorsal horn and intermediate zone at E14. The present findings indicated that the spatiotemporal changes of NGF, BDNF and NT-3 could be associated to the morphological changes of developing spinal cords, suggesting the possible roles of three growth factors in the development of spinal cords.

[Endogenous BDNF promote regeneration of injured nervous system].

OBJECTIVE: To test the effect of endogenous BDNF on injured nervous system. METHODS: The left sciatic nerves of the rats were cut off, and then divided into two groups, each with 8 rats. The rats in the experimental group were intraperitoneally injected with anti-BDNF, while the control group was given normal sheep serum (NSS). The dorsal coclums of the rats were cut on the 8th day. The L5 DRG were cut into length wise sections to dye with fluorescent antibody. Positive cells of GAP-43 in the L5 DRG were counted. The second experiment had both sides of sciatic nerves of the rats cut off, followed by the same procedure as the first experiment. The HRP tracing and ABC immunohistochemical staining were performed to analyse the effect of endogenous BDNF on the recovery of injured spinal cords. RESULTS: For the rats with left sciatic nerves cut off, the experimental group had less GAP-43 positive cells in the left L5 DRG than the controls (P<0.01). For the rats with both sciatic nerves cut off, the experimental group had less nerves with positive fibers-labeled HRP than the controls at the site of tSCI (P<0.01). CONCLUSION: Endogenous BDNF promote the recovery of injured nervous system.

Role of Neurotrophin 3 in spinal neuroplasticity in rats subjected to cord transection.

That neuroplasticity occurs in mammalian spinal cord is well known, though the underlying mechanism still awaits elucidation. This study evaluated the role of endogenous Neurotrophin-3 (NT-3) in the spinal neuroplasticity. Following cord transection at the junction between T9 and T10, the hindlimb locomotor functions of rats showed gradual but significant improvement from 7 to 28 days post-operation. Corresponding to this was a significant increase in the level of NT-3 in the cord segments caudal to injury site. Significantly, after NT-3-antibody administration, the spinal transected rats displayed poor hindlimb locomotor functions and a decrease in the number of neurons in spinal laminae VIII-IX. Whether NT-3-antibody was administered, corticospinal tract regeneration and somatosensory evoked potentials could not be detected. Our findings suggested that endogenous NT-3 could play an important role in spinal plasticity in adult spinal cords subjected to transection, possibly through a regulation of neuronal activity in the local circuitry.

Changes in Glial cell line-derived neurotrophic factor expression in the rostral and caudal stumps of the transected adult rat spinal cord.

Limited information is available regarding the role of endogenous Glial cell line-derived neurotrophic factor (GDNF) in the spinal cord following transection injury. The present study investigated the possible role of GDNF in injured spinal cords following transection injury (T(9)-T(10)) in adult rats. The locomotor function recovery of animals by the BBB (Basso, Beattie, Bresnahan) scale score showed that hindlimb support and stepping function increased gradually from 7 days post operation (dpo) to 21 dpo. However, the locomotion function in the hindlimbs decreased effectively in GDNF-antibody treated rats. GDNF immunoreactivty in neurons in the ventral horn of the rostral stump was stained strongly at 3 and 7 dpo, and in the caudal stump at 14 dpo, while immunostaining in astrocytes was also seen at all time-points after transection injury. Western blot showed that the level of GDNF protein underwent a rapid decrease at 7 dpo in both stumps, and was followed by a partial recovery at a later time-point, when compared with the sham-operated group. GDNF mRNA-positive signals were detected in neurons of the ventral horn, especially in lamina IX. No regenerative fibers from corticospinal tract can be seen in the caudal segment near the injury site using BDA tracing technique. No somatosensory evoked potentials (SEP) could be recorded throughout the experimental period as well. These findings suggested that intrinsic GDNF in the spinal cord could play an essential role in neuroplasticity. The mechanism may be that GDNF is involved in the regulation of local circuitry in transected spinal cords of adult rats.