Apelin inhibits motor neuron apoptosis in the anterior horn following acute spinal cord and sciatic nerve injuries

Rat models of acute spinal cord injury and sciatic nerve injury were established.Apelin expression in spinal cord tissue was determined.In normal rat spinal cords,apelin expression was visible;however,2 hours post spinal cord injury,apelin expression peaked.Apelin expression increased 1 day post ligation of the sciatic nerve compared with normal rat spinal cords,and peaked at 3 days.Apelin expression was greater in the posterior horn compared with the anterior horn at each time point when compared with the normal group.The onset of neuronal apoptosis was significantly delayed following injection of apelin protein at the stump of the sciatic nerve,and the number of apoptotic cells after injury was reduced when compared with normal spinal cords.Our results indicate that apelin is expressed in the normal spinal cord and central nervous system after peripheral nerve injury.Apelin protein can reduce motor neuron apoptosis in the spinal cord anterior horn and delay the onset of apoptosis.     

Craniocerebral injury promotes the repair of peripheral nerve injury

The increase in neurotrophic factors after craniocerebral injury has been shown to promote fracture healing. Moreover, neurotrophic factors play a key role in the regeneration and repair of peripheral nerve. However, whether craniocerebral injury alters the repair of peripheral nerve injuries remains poorly understood. Rat injury models were established by transecting the left sciatic nerve and using a free-fall device to induce craniocerebral injury. Compared with sciatic nerve injury alone after 6–12 weeks, rats with combined sciatic and craniocerebral injuries showed decreased sciatic functional index, increased recovery of gastrocnemius muscle wet weight, recovery of sciatic nerve ganglia and corresponding spinal cord segment neuron morphologies, and increased numbers of horseradish peroxidase-labeled cells. These results indicate that craniocerebral injury promotes the repair of peripheral nerve injury.     

Nischarin-siRNA delivered by polyethylenimine-alginate nanoparticles accelerates motor function recovery after spinal cord injury

A previous study by our group found that inhibition of nischarin promotes neurite outgrowth and neuronal regeneration in Neuro-2 a cells and primary cortical neurons.In recent years,more and more studies have shown that nanomaterials have good prospects in treatment of spinal cord injury.We proposed that small interfering RNA targeting nischarin(Nis-si RNA) delivered by polyethyleneimine-alginate(PEIALG) nanoparticles promoted motor function recovery in rats with spinal cord injury.Direct microinjection of 5 μL PEI-ALG/Nis-si RNA into the spinal cord lesion area of spinal cord injury rats was performed.From day 7 after surgery,Basso,Beattie and Bresnahan score was significantly higher in rats from the PEI-ALG/Nis-si RNA group compared with the spinal cord injury group and PEI-ALG/Control-si RNA group.On day 21 after injection,hematoxylin-eosin staining showed that the necrotic area was reduced in the PEI-ALG/Nis-si RNA group.Immunohistochemistry and western blot assay results confirmed successful inhibition of nischarin expression and increased protein expression of growth-associated protein-43 in the PEI-ALG/Nis-si RNA group.These findings suggest that a complex of PEI-ALG nanoparticles and Nis-si RNA effectively suppresses nischarin expression,induces expression of growth-associated protein-43,and accelerates motor function recovery after spinal cord injury.     

Thermomineral water promotes axonal sprouting but does not reduce glial scar formation in a mouse model of spinal cord injury

Thermomineral water from the Atomic Spa Gornja Trepca has been used for a century in the treatment of neurologic disease. The thermomineral water contains microelements, including lithium and magnesium, which show neural regeneration-promoting effects after central nervous system injury. In this study, we investigated the effects of oral intake of thermomineral water from the Atomic Spa Gornja Trepca on nerve regeneration in a 3-month-old mouse model of spinal cord injury. The mice receiving oral intake of thermomineral water showed better locomotor recovery than those without administration of thermomineral water at 8 and 12 weeks after lower thoracic spinal cord compression. At 12 weeks after injury, sprouting of catecholaminergic axons was better in mice that drank thermomineral water than in those without administration of thermomineral water, but there was no difference in glial reaction to injury between mice with and without administration of thermomineral water. These findings suggest that thermomineral water can promote the nerve regeneration but cannot reduce glial scar formation in a mouse model of spinal cord injury.     

Hyperbaric oxygen therapy improves local microenvironment after spinal cord injury

Clinical studies have shown that hyperbaric oxygen therapy improves motor function in patients with spinal cord injury. In the present study, we explored the mechanisms associated with the recovery of neurological function after hyperbaric oxygen therapy in a rat model of spinal cord injury. We established an acute spinal cord injury model using a modification of the free-falling object method, and treated the animals with oxygen at 0.2 MPa for 45 minutes, 4 hours after injury. The treatment was administered four times per day, for 3 days. Compared with model rats that did not receive the treatment, rats exposed to hyperbaric oxygen had fewer apoptotic cells in spinal cord tissue, lower expression levels of aquaporin 4/9 mRNA and protein, and more NF-200 positive nerve fibers. Furthermore, they had smaller spinal cord cavities, rapid recovery of somatosensory and motor evoked potentials, and notably better recovery of hindlimb motor function than model rats. Our findings indicate that hyperbaric oxygen therapy reduces apoptosis, downregulates aquaporin 4/9 mRNA and protein expression in injured spinal cord tissue, improves the local microenvironment for nerve regeneration, and protects and repairs the spinal cord after injury.     

Ursolic acid induces neural regeneration after sciatic nerve injury

In this study,we aimed to explore the role of ursolic acid in the neural regeneration of the injured sciatic nerve.BALB/c mice were used to establish models of sciatic nerve injury through unilateral sciatic nerve complete transection and microscopic anastomosis at 0.5 cm below the ischial tuberosity.The successfully generated model mice were treated with 10,5,or 2.5 mg/kg ursolic acid via intraperitoneal injection.Enzyme-linked immunosorbent assay results showed that serum S100 protein expression level gradually increased at 1-4 weeks after sciatic nerve injury,and significantly decreased at 8 weeks.As such,ursolic acid has the capacity to significantly increase S100 protein expression levels.Real-time quantitative PCR showed that S100 mRNA expression in the L4-6 segments on the injury side was increased after ursolic acid treatment.In addition,the muscular mass index in the soleus muscle was also increased in mice treated with ursolic acid.Toluidine blue staining revealed that the quantity and average diameter of myelinated nerve fibers in the injured sciatic nerve were significantly increased after treatment with ursolic acid.10 and 5 mg/kg of ursolic acid produced stronger effects than 2.5 mg/kg of ursolic acid.Our findings indicate that ursolic acid can dose-dependently increase S100 expression and promote neural regeneration in BALB/c mice following sciatic nerve injury.     

Curcumin upregulates S100 expression and improves regeneration of the sciatic nerve following its complete amputation in mice

The repair of peripheral nerve injury after complete amputation is difficult,and even with anastomosis,the rapid recovery of nerve function remains challenging.Curcumin,extracted from plants of the genus Curcuma,has been shown to have anti-oxidant and anti-inflammatory properties and to improve sciatic nerve crush injury in rats.Here,we determined whether curcumin had neuroprotective effects following complete peripheral nerve amputation injury.BALB/c mice underwent complete sciatic nerve amputation,followed by an immediate epineurium anastomosis.Mice were intragastrically administered curcumin at doses of 40(high),20(moderate),and 10 mg/kg/d(low) for 1 week.We found that myelin in the mice of the high- and moderate-dose curcumin groups appeared with regular shape,uniform thickness,clear boundary,and little hyperplasia surrounding the myelin.High and moderate doses of curcumin markedly improved both action potential amplitude of the sciatic nerves and the conduction velocity of the corresponding motor neurons,and upregulated m RNA and protein expression of S100,a marker for Schwann cell proliferation,in L4–6 spinal cord segments.These results suggest that curcumin is effective in promoting the repair of complete sciatic nerve amputation injury and that the underlying mechanism may be associated with upregulation of S100 expression.     

Biodegradable chitin conduit tubulation combined with bone marrow mesenchymal stem cell transplantation for treatment of spinal cord injury by reducing glial scar and cavity formation

We examined the restorative effect of modified biodegradable chitin conduits in combination with bone marrow mesenchymal stem cell transplantation after right spinal cord hemisection injury. Immunohistochemical staining revealed that biological conduit sleeve bridging reduced glial scar formation and spinal muscular atrophy after spinal cord hemisection. Bone marrow mesenchymal stem cells survived and proliferated after transplantation in vivo, and differentiated into cells double-positive for S100(Schwann cell marker) and glial fibrillary acidic protein(glial cell marker) at 8 weeks. Retrograde tracing showed that more nerve fibers had grown through the injured spinal cord at 14 weeks after combination therapy than either treatment alone. Our findings indicate that a biological conduit combined with bone marrow mesenchymal stem cell transplantation effectively prevented scar formation and provided a favorable local microenvironment for the proliferation, migration and differentiation of bone marrow mesenchymal stem cells in the spinal cord, thus promoting restoration following spinal cord hemisection injury.     

7, 8-dihydroxycoumarin improves neurological function in a mouse model of sciatic nerve injury

In the present study, a mouse model of sciatic nerve injury was treated with intraperitoneal injection of 7, 8-dihydroxycoumarin (10, 5, or 2.5 mg/kg per day). Western blot and real-time PCR results showed that growth associated protein 43 expression was significantly increased in the L4-6 seg-ments of the spinal cord. The amplitude and velocity of motor nerve conduction in the sciatic nerve were significantly increased in model mice. In addition, the appearance of the myelin sheath in the injured sciatic nerve was regular, with an even thickness and clear outline, and the surrounding fi-broplasia was not obvious. Our results indicate that 7, 8-dihydroxycoumarin can promote the repair of injured nerve by upregulating growth associated protein 43 expression in the corresponding spinal cord segments of mice with sciatic nerve injury.     

Effects of 660‐nm gallium–aluminum–arsenide low‐energy laser on nerve regeneration after acellular nerve allograft in rats

Purpose : The purpose of this study was to explore and discuss the effects of 660‐nm gallium–aluminum–arsenide low‐energy laser (GaAlAs LEL) irradiation on neural regeneration after acellular nerve allograft repair of the sciatic nerve gap in rats. Methods : Eight male and female Sprague–Dawley rats were used as nerve donors, and 32 healthy Wistar rats were randomly divided into four groups: normal control group, acellular rat sciatic nerve (ARSN) group, laser group, and autograft group. Twelve weeks after surgery, nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, myelinated nerve number, and calcitonin gene‐related peptide (CGRP) protein and mRNA expression of the spinal cord and muscle at the injury site were quantified and statistically analyzed. Results : Compared with the ARSN group, laser therapy significantly increased nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, myelinated nerve number, and CGRP protein and mRNA expression of the L₄ spinal cord at the injury site. Conclusions : These findings demonstrate that 660‐nm GaAlAs LEL therapy upregulates CGRP protein and mRNA expression of the L₄ spinal cord at the injury site and increases the rate of regeneration and target reinnervation after acellular nerve allograft repair of the sciatic nerve gap in rats. Low‐energy laser irradiation may be a useful, noninvasive adjunct for promoting nerve regeneration in surgically induced defects repaired with ARSN. Synapse 64:152–160, 2010. © 2009 Wiley‐Liss, Inc.     

GAP-43 mRNA in Rat Spinal Cord and Dorsal Root Ganglia Neurons: Developmental Changes and Re-expression Following Peripheral Nerve Injury

The expression of growth-associated protein GAP-43 mRNA in spinal cord and dorsal root ganglion (DRG) neurons has been studied using an enzyme linked in situ hybridization technique in neonatal and adult rats. High levels of GAP-43 mRNA are present at birth in the majority of spinal cord neurons and in all dorsal root ganglion cells. This persists until postnatal day 7 and then declines progressively to near adult levels (with low levels of mRNA in spinal cord motor neurons and 2000–3000 DRG cells expressing high levels) at postnatal day 21. A re-expression of GAP-43 mRNA in adult rats is apparent, both in sciatic motor neurons and the majority of L4 and L5 dorsal root ganglion cells, 1 day after sciatic nerve section. High levels of the GAP-43 mRNA in the axotomized spinal motor neurons persist for at least 2 weeks but decline 5 weeks after sciatic nerve section, with the mRNA virtually undetectable after 10 weeks. The initial changes after sciatic nerve crush are similar, but by 5 weeks GAP-43 mRNA in the sciatic motor neurons has declined to control levels. In DRG cells, after both sciatic nerve section or crush, GAP-43 mRNA re-expression persists much longer than in motor neurons. There was no re-expression of GAP-43 mRNA in the dorsal horn of the spinal cord after peripheral nerve lesions. Our study demonstrates a similar developmental regulation in spinal cord and DRG neurons of GAP-43 mRNA. We show moreover that failure of re-innervation does not result in a maintenance of GAP-43 mRNA in axotomized motor neurons.     

氧化巴西苏木素干预BALB/c小鼠坐骨神经损伤

氧化巴西苏木素已经被证实对中枢神经的再生具有免疫调节作用,但其对坐骨神经损伤的效应尚无共识。应用Western blot及Real-time PCR的检测显示,经16,8 g/kg氧化巴西苏木素干预后,坐骨神经损伤小鼠L4~6脊髓节段的S100蛋白和mRNA明显高于4g/kg氧化巴西木素干预的小鼠及模型组。髓鞘固兰染色显示,16,8 g/kg氧化巴西木素干预的神经再生情况也明显优于4g/kg氧化巴西木素干预及模型组。同时电生理检查和免疫组化检测进一步证实了氧化巴西苏木素对BALB/c小鼠坐骨神经损伤有修复作用。由此认为,氧化巴西苏木素对脊髓前角细胞中S100有活化作用,促进了坐骨神经再生与修复,且以高中剂量最为显著。     

The mechanism of astragaloside IV promoting sciatic nerve regeneration

3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-cycloastragenol (astragaloside Ⅳ), the main active component of the traditional Chinese medicine astragalus membranaceus, has been shown to be neuroprotective. This study investigated whether astragaloside Ⅳ could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day for 8 consecutive days. Western blot assay and real-time PCR results demonstrated that growth-associated protein-43 expression was upregulated in mouse spinal cord segments L4-6 after intervention with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day in a dose-dependent manner. Luxol fast blue staining and electrophysiological detection suggested that astragaloside Ⅳ elevated the number and diameter of myelinated nerve fibers, and simultaneously increased motor nerve conduction velocity and action potential amplitude in the sciatic nerve of mice. These results indicated that astragaloside Ⅳ contributed to sciatic nerve regeneration and functional recovery in mice. The mechanism underlying this effect may be associated with the upregulation of growth-associated protein-43 expression.     

Propofol's effect on the sciatic nerve: Harmful or protective?

Propofol can inhibit the inflammatory response and reduce the secretion and harmful effects of astrocyte-derived proinflammatory cytokines.In this study,after propofol was injected into the injured sciatic nerve of mice,nuclear factor kappa B expression in the L4-6 segments of the spinal cord in the injured side was reduced,apoptosis was decreased,nerve myelin defects were alleviated,and the nerve conduction block was lessened.The experimental findings indicate that propofol inhibits the inflammatory and immune responses,decreases the expression of nuclear factor kappa B,and reduces apoptosis.These effects of propofol promote regeneration following sciatic nerve injury.     

Study on molecular mechanism for improving neural regeneration after repair of sciatic nerve defect in rat by acellular nerve allograft

Objective: Discuss the molecular mechanism for improving neural regeneration after repair of sciatic nerve defect in rat by acellular nerve allograft (ANA). Methods: Randomly divide 36 Wistar rats into six groups as normal control group, autografting group, and bridging groups of 2, 4, 8, 12 weeks, six rats for each group. Observe the expression of brain‐derived neurotrophic factor (BDNF) in L₄ spinal cord and anterior tibial muscle at the injury site, calcitonin gene‐related peptide (CGRP) protein as well as mRNA, respectively. 12w after operation, histopathological observation was performed. Results: 2w after ANA bridging the sciatic nerve defect in rats, it was observed that the expression level of BDNF in spinal cord at the injury site and CGRP protein increased, reaching the peak level at 4w, lasting till 8w, then decreased but still significantly higher than that in normal control group at 12w, and was not significantly different compared with that in autografting group. However, the expression level of BDNF in anterior tibial muscle decreased gradually within the initial 4w, then increased progressively, reaching normal level at 12w, and was not significantly different compared with that in autografting group. The expression of BDNF mRNA and CGRPmRNA was essentially the same. 12w after operation, there was nerve regeneration in bridging group of 12w and autografting group. Conclusions: ANA possessed fine histocompatibility, and might substitute autograft to repair long‐segment defect of sciatic nerve in rats. This action might be related to upregulation of protein and mRNA expression for BDNF and CGRP in spinal cord. Synapse, 2012. © 2011 Wiley Periodicals, Inc.     

Glial cell line-derived neurotrophic factor enhances axonal regeneration following sciatic nerve transection in adult rats

Adult rat sciatic nerve was transected and sutured with an entubulation technique. The nerve interstump gap was filled with either collagen gel (COL) or collagen gel mixed with glial cell line-derived neurotrophic factor (COL/GDNF). Four weeks after nerve transection, horseradish peroxidase (HRP)-labelled spinal cord motoneurons and the myelinated distal stump axons were quantified. Compared with the COL group, the percentages of labeled spinal somas and axon number were significantly increased after topically applied glial cell line-derived neurotrophic factor (GDNF). The functional recovery of the transected nerve was improved in COL/GDNF group. GAP-43 expression was also significantly higher in COL/GDNF group 1 and 2 weeks after sciatic nerve axotomy vs. COL group. These data provide strong evidence that GDNF could promote axonal regeneration in adult rats, suggesting the potential use of GDNF in therapeutic approaches to peripheral nerve injury and neuropathies.