Sciatic Nerve Of Wistar Rats Research Articles

Nigella sativa oil on chronic constrictive injury (CCI) induced neuropathic pain of sciatic nerve in Wistar rats

Background: Various adverse effects have been reported with conventional treatments of neuropathic pain. Nigella sativa (N. sativa), a medicinal herb, has been shown to possess several beneficiary effects. Objective: To assess the effects of N. sativa oil on neuropathic pain and ATP sensitive potassium channel (KATP) in Wistar rats. Methods: This experimental study was conducted on 120 Wistar rats (200±50gm). On the basis of treatments, all rats were grouped into Group I [normal control (NC) normal saline (NS) 5 ml/kg]; Group II [sham control (SC) {sham surgery + NS}], Group III [CCI control (CCIC) {Chronic constriction injury to sciatic nerve (CCI) + NS}]; Group IV [N. sativa oil experimental (NSOexp) {CCI + N.sativa (400 mg/kg)}], Group V [Glibenclamide experimental (Gliexp) {CCI + N. sativa (400 mg/kg) + glibenclamide (15 mg/kg)}] groups. Both the NSO and NS were administered orally once daily for consecutive 21 days and single dose of glibenclamide was given intraperitoneally on the day of experiment, to the respective rats. Then on the basis of neuropathic pain evaluation tests, all the groups were subdivided into ‘a’ [for sciatic functional index (SFI) in walking track analysis], ‘b’ [for tail flick latency (TFL) in cold tail immersion test], ‘c’ [for paw withdrawal threshold (PWT) in von Frey test], and ‘d’ (for rection time in hot plate test). The statistical analysis was done by one way ANOVA followed by Bonferroni post hoc test. Results: In this study, significantly (pd”0.001) higher SFI, TFL, PWT and reaction time were found in NSO exp rats when compared to those of CCIC rats. In addition, there were significant (pd”0.001) differences in the above-mentioned variables between rats of NSO exp group and Gliexp group. Conclusion: From the present study it might be concluded that, N. sativa prevents worsening of neuropathic pain in Wistar rats by blocking KATP channel. J Bangladesh Soc Physiol 2023;18(1): 35-45

Pitavastatin attenuates neuropathic pain induced by partial sciatic nerve in Wistar rats.

Pitavastatin is a competitive HMG-CoA reductase inhibitor for lowering of cholesterol level and low density lipoprotein cholesterol. This study was designed to evaluate the effect of pitavastatin in neuropathic pain induced by partial sciatic nerve ligation along with neuronal changes in Wister rats. Pitavastatin was started three days prior to the surgery and continued for 14 days The pain was determined by thermal hyperalgesia and cold allodynia. The biochemical changes were estimated at the end of the study. The levels of cytokines were measured using an ELISA test. Western blot analysis was used to detect levels of expression of JNK, p-JNK, ERK, p-ERK, p38MAPK, p-p38MAPK. The sciatic nerve was investigated histopathologically. Pitavastatin significantly ameliorated nerve pain induced by PSNL and also attenuated the biochemical changes in a dose-dependent manner. The levels of inflammatory mediators were inhibited by pitavastatin. There was significant improvement in sciatic nerve fibres histology. The levels of p-38, p-ERK, and p-JNK and their associated phosphorylated proteins were reduced after treatment with pitavastatin. The present study indicates that treatment with pitavastatin reversed the PSNL-induced neuropathy in Wister rats and may be an additional therapeutic strategy in the management of neuropathic pain.

Effect of immediate electrical stimulation in the distal segment of the nerve with Wallerian degeneration in rats with sciatic nerve injury

BACKGROUND Electrical stimulation in the proximal segment is one of the modalities for peripheral nerve injury, although it is prone to cause excessive axonal sprouting growth in the proximal segment of the nerve. This study aimed to show that immediate electrical stimulation in the distal segment of the sciatic nerve in Wistar rats accelerated Wallerian degeneration by increasing the expression of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-10, and galectin-3/MAC-2 macrophages to avoid sprouting axons excessively in the proximal segment.
 METHODS This was an experimental study using male Wistar rats (Rattus norvegicus) with a randomized post-test only control group design. The treatment group received immediate electrical stimulation (20 Hz, 2 mA, for 5 sec) to the distal nerve after sciatic nerve injury, while the control group received no treatment. After 3 days, tissue samples were extracted from the distal segment of the sciatic nerve to examine the level of TNF-α, IL-10, and galectin 3/Mac-2 macrophages using ELISA and from proximal nerves to histologically examine the sprouting axons.
 RESULTS Rats in the treatment group had higher TNF-α (52.1 [10.32] versus 40.4 [17.71] pg/100 mg, p = 0.031) and higher IL-10 (918 [167.6] versus 759 [158.9] pg/ml, p = 0.010). Expression of galectin 3/Mac-2 macrophages was similar in both groups (465 [49.5] versus 444 [54.4] pg/100 mg, p = 0.247). The number of sprouting axons was lower in the treatment group (2 [IQR 1–2] versus 2.5 [IQR 2–3], p = 0.003).
 CONCLUSIONS Immediate electrical stimulation in the distal segment of the sciatic nerve can accelerate nerve regeneration.

Effects of Azadirachta indica on neuropathic pain induced by chronic constriction injury to sciatic nerve of Wistar rat.

The research was designed to assess the consequences of Azadirachta indica aqueous leaf extract (AILE) on neuropathic pain in Wister rats and the role of the ATP-dependent potassium channel (KATP) as an underlying mechanism. This experimental layout was conducted on Wistar rats (n = 120) having 150 to 200 gm of body weight. On the foundation of the experimental design, rats were divided into group I (normal saline, 5 ml/kg/body weight) and group II (sham surgery and treatment with NS), group III [chronic constriction injury (CCI) in the sciatic nerve; and treated with NS], group IV (CCI and treated with AILE 400 mg/kg body weight), Group V (CCI, pretreated with Glibenclamide 15 mg/kg followed by treated with AILE 400 mg/kg). All the treatments were given once daily for a consecutive 21 days via the oral route, except Glibenclamide. Glibenclamide was given once through the intraperitoneal route on the day of the experiment. Based on the neuropathic pain evaluation test, all groups were again sub-divided into subgroup "a" (walking tract analysis), "b" (cold tail immersion test), "c" (Von Frey test), and "d" (hot plate test). AILE showed a significantly higher sciatic functional index (p < 0.05) in walking track analysis, tail flick latency (p ≤ 0.05) in the cold tail immersion test, and paw withdrawal threshold (p ≤ 0.05) in the Von Frey test compared to CCI control. In addition, a nonsignificant difference in all these above-mentioned variables between the rats with CCI plus AILE and the CCI plus AILE plus glibenclamide group indicated that the KATP channel was not involved in the beneficial analgesic effects of AILE. The outcome of the present study indicates that AILE prevented worsening of neuropathic pain after chronic constriction injury in the sciatic nerve of Wistar rats in which the KATP channel was not involved.

Efficacy of multi-wave locked system laser therapy on nerve regeneration after crushing in Wister rats.

[Purpose] To investigate the efficacy of the multi-wave locked system laser therapy on the regeneration of peripheral nerve injuries by evaluating the functional, electrophysiological, and morphological changes of the crushed sciatic nerve in Wistar rats. [Materials and Methods] Sixty male Wistar rats (200–250 g) were randomly assigned to control negative, control positive, or laser groups and subjected to no laser therapy or crushing, to crushing without laser therapy, or crushing followed by multi-wave locked system laser therapy five times/week for four weeks (power=1 W, energy density=10 J/cm2, total energy=100 J), respectively. Functional, electrophysiological, and morphometric analyses were performed before and 7, 15, 21, and 28 days after crushing. The sciatic functional index, compound motor action potential amplitude, motor nerve conduction velocity, and nerve and myelin sheath diameters were measured. [Results] The sciatic functional index value decreased significantly, while the compound motor action potential amplitude, motor nerve conduction velocity, nerve diameter, and myelin sheath diameter increased significantly in the laser group post-treatment compared to the values in the control groups. [Conclusion] Multi-wave locked system laser therapy was effective in accelerating the regeneration of crushed sciatic nerves in Wistar rats.

Chronic constriction injury of the sciatic nerve in rats causes different activation modes of microglia between the anterior and posterior horns of the spinal cord

Chronic constriction injury of the sciatic nerve is frequently considered as a cause of chronic neuropathic pain. Marked activation of microglia in the posterior horn (PH) has been well established with regard to this pain. However, microglial activation in the anterior horn (AH) is also strongly induced in this process. Therefore, in this study, we compared the differential activation modes of microglia in the AH and PH of the lumbar cord 7 days after chronic constriction injury of the left sciatic nerve in Wistar rats. Microglia in both the ipsilateral AH and PH demonstrated increased immunoreactivity of the microglial markers Iba1 and CD11b. Moreover, abundant CD68+ phagosomes were observed in the cytoplasm. Microglia in the AH displayed elongated somata with tightly surrounding motoneurons, whereas cells in the PH displayed a rather ameboid morphology and were attached to myelin sheaths rather than to neurons. Microglia in the AH strongly expressed NG2 chondroitin sulfate proteoglycan. Despite the tight attachment to neurons in the AH, a reduction in synaptic proteins was not evident, suggesting engagement of the activated microglia in synaptic stripping. Myelin basic protein immunoreactivity was observed in the phagosomes of activated microglia in the PH, suggesting the phagocytic removal of myelin. CCI caused both motor deficit and hyperalgesia that were evaluated by applying BBB locomotor rating scale and von Frey test, respectively. Motor defict was the most evident at postoperative day1, and that became less significant thereafter. By contrast, hyperalgesia was not severe at day 1 but it became worse at least by day 7. Collectively, the activation modes of microglia were different between the AH and PH, which may be associated with the difference in the course of motor and sensory symptoms.

Bromelain reversed electrolyte imbalance in the chronically constricted sciatic nerve of Wistar rats.

Derangement of electrolyte in the sensory nervous system has been attributed to the development and maintenance of hyperalgesic and allodynic symptoms in painful neuropathy. This study investigated the effect of bromelain on electrolyte imbalance in chronically constricted sciatic nerve of rats (a model of neuropathic pain). Forty Wistar rats, divided into five groups of eight animals each were used for this study. von Frey filaments, tail immersion and acetone spray tests were used to assessed allodynic and thermal hyperalgesic symptoms in the Wistar rats. Sodium ion (Na+), potassium ion (K+), calcium ion (Ca2+) and chloride ion (Cl-) concentrations as well as sodium-potassium and calcium electrogenic pump (Na-K ATPase and Ca ATPase, respectively) activities were estimated using spectrophotometry techniques. Bromelain significantly (p < 0.05) reversed elevation of Na+ and Ca2+ concentration compared with sciatic nerve chronic constriction injury (snCCI) group (35.68 ± 1.71 vs 44.46 ± 1.24 mg/ml/mg protein and 1.06 ± 0.19 vs 6.66 ± 0.03 mg/ml/mg protein, respectively). There were also significant (p < 0.05) increases in the level of K+ (0.84 ± 0.02 vs 0.36 ± 0.05 mg/ml/mg protein) and Cl- (18.51 ± 0.29 vs 15.82 ± 0.21 mg/ml/mg protein). Bromelain reduced the activities of Ca2+ electrogenic pumps significantly compared with snCCI. This study therefore suggests that bromelain mitigated electrolyte imbalance in chronic constricted injury of the sciatic nerve implying that this may be an important mechanism for the anti-nociceptive effect of bromelain.

Axonal excitability and conduction alterations caused by levobupivacaine in rat.

In this study, effects of the long-acting amide-type local anesthetic levobupivacaine on axonal conduction and excitability parameters of the rat sciatic nerve were thoroughly examined both in vitro and in vivo. In order to deduce its effects on isolated nerve conduction, compound nerve action potential (CNAP) recordings were performed using the suction method over sciatic nerves of Wistar rats before and after administration of 0.05 % (1.7 mmol L-1) levobupivacaine. Levobupivacaine caused complete CNAP area and amplitude depression by blocking conduction in a time-dependent manner. To assess the influence of levobupivacaine on in vivo excitability properties, threshold-tracking (TT) protocols were performed at sciatic nerves of rats injected with perineural 0.05 % (1.7 mmol L-1) levobupivacaine or vehicle alone. Charge-duration TT results revealed that levobupivacaine increases the rheobase and decreases the strength-duration time constant, suggesting interference of the anesthetic with the opening of Na+ channels. Twenty and 40 % threshold electrotonus curves were found for both groups to follow the same paths, suggesting no significant effect of levobupivacaine on K+ channels for either the fastest or relatively slow conducting fibers. Current-threshold relationship results revealed no significant effect on axonal rectifying channels. However, according to the results of the recovery cycle protocol yielding the pattern of excitability changes following the impulse, potential deviation was found in the recovery characteristics of Na+ channels from the absolute refractory period. Consequently, conduction blockage caused by levobupivacaine may not be due to the passive (capacitive) properties of axon or the conductance of potassium channels but to the decrease in sodium channel conductance.

DIFERENTES RESPOSTAS DO TECIDO ÓSSEO E ARTICULAR DE RATOS WISTAR, SUBMETIDOS A EXERCÍCIO RESISTIDO, APÓS LESÃO NERVOSA

Objetivo: analisar o efeito do exercício resistido de subida em escadas nos tecidos ósseo e articular, após lesão compressiva do nervo isquiático de ratos Wistar. Material e Métodos: 32 ratos foram divididos aleatoriamente em 4 grupos, com 8 animais em cada, G1 (controle), G2 (exercício), G3 (lesão) e G4 (lesão e exercício). Após a lesão nervosa G2 e G4 foram submetidos ao exercício resistido de subida em escada, durante 5 dias na semana, com intervalo de 2 dias, por 21 dias. Os animais foram eutanasiados e as articulações do joelho e tíbias do membro pélvico lesionado foram coletadas, e seguiram o processamento padrão para análises em microscopia de luz. Resultados: O tecido ósseo apresentou alterações significativas, em relação a análise morfométrica da área do canal medular e contagem e osteócitos, porém, não foi observada diferença significativa em relação a análise da espessura do osso cortical. Na cartilagem articular do joelho foram observadas discretas alterações morfológicas entre os grupos, como a presença de clones celulares no grupo G3 e remodelagem no grupo G4. Conclusão: a lesão do nervo isquiático em ratos Wistar trouxe efeitos deletérios ao tecido ósseo e articular. Também foi observado que o exercício físico resistido em subida de escada não trouxe alterações ao tecido ósseo dos animais, porém, foi eficaz ao retorno às características normais da cartilagem articular lesionada, e demonstrou aumento da evidencia da tidemark, em animais não lesionados.

Aspects of the Macro and Microscopic Anatomy of the Sciatic Nerve in Wistar Rats

El objetivo fue sistematizar los parametros morfologicos y morfometricos y traer nuevos datos sobre el ramo principal del plexo lumbosacro - es decir nervio ciatico - en ratas Wistar de 4 a 7 semanas. Dieciseis ratas fueron divididas en dos grupos, con 4 y 7 semanas de edad. Las muestras estudiadas fueron los segmentos proximal y distal del nervio ciatico derecho. Secciones delgadas (espesor 0,25 mm) fueron tenidas con azul de toluidina al 1 % y el analisis morfometrico se llevo a cabo utilizando el programa KS 400. Excepto para el numero de fasciculos y diametro fascicular, no se encontraron diferencias entre los segmentos proximal y distal. Fueron observadas diferencias cuando se compararon los valores morfometricos entre animales de 4 y 7 semanas, con algunas excepciones (numero de fasciculos y fibras mielinizadas, area y numero de capilares). Los datos macroscopicos no estan de acuerdo con la descripcion anterior del nervio ciatico siendo compuesto por dos fasciculos. En cambio, solo trifurcacion o cuadrifurcacion fueron encontrados en el tercio distal del muslo. El area total capilar y la densidad fueron calculadas y estos constituyen los primeros datos de referencia para el nervio ciatico. Se construyeron histogramas de fibras mielinicas y axones, teniendo en cuenta las edades de los animales. Los resultados presentados aqui son importantes porque los estudios experimentales, en especial aquellos sobre la regeneracion nerviosa, requieren comparacion con datos confiables normales.

Nociceptive and Neuronal Evaluation of the Sciatic Nerve of Wistar Rats Subjected to Compression Injury and Treated with Resistive Exercise.

Background. To investigate the climb stairs resistance exercise on nociception and axonal regeneration in the sciatic nerve of rats. Methods. 24 Wistar rats were divided: control group (CG—no injury), exercise group (EG—no injury with physical exercise), lesion group (LG—injury, but without exercise), and treated group (LEG—injury and physical exercise). LG and LEG were subjected to sciatic nerve compression with hemostat. From the 3rd day after injury began treatment with exercise, and after 22 days occurs the removal of a nerve fragment for morphological analysis. Results. Regarding allodynia, CG obtained values less than EG (p = 0.012) and larger than LG and LEG (p < 0.001). Histological results showed that CG and EG had normal appearance, as LG and LEG showed up with large amounts of inflammatory infiltration, degeneration and disruption of nerve fibers, and reduction of the myelin sheath; however LEG presented some regenerated fibers. From the morphometric data there were significant differences, for nerve fiber diameter, comparing CG with LG and LEG and comparing axon diameter and the thickness of the myelin of the CG to others. Conclusion. Climb stairs resistance exercise was not effective to speed up the regenerative process of axons.

Comparative study of the efficacy of decellularization treatment of allogenic and xenogeneic nerves as nerve conduits.

The objective of this study was to compare the results of allogenic and xenogeneic nerve grafts that were treated using decellularization. The sciatic nerves of Sprague-Dawley rats and the median nerves of Japanese white rabbits were decellularized with sodium dodecyl sulfate and Triton X-100 and examined with a scanning electron microscope and immunofluorescence staining. A bridge-graft into the sciatic nerve in Wistar rats was performed with the decellularized nerves (10 mm in length for short-term evaluation; 15 mm in length for long-term evaluation). As a control, an isograft was performed. The specimens were harvested at 4 weeks postoperatively and prepared for immunohistochemistry. Function, electrophysiological and histomorphological analyses were performed to evaluate nerve recovery at 24 weeks postoperatively. The 3-dimensional structure of the basal lamina column, on which the cell adhesion molecules were integrated, was preserved through the decellularization protocols. Limited ED1-positive macrophage invasion was observed, and abundant NF 160-positive axons, which were accompanied by S-100-positive Schwann cells, penetrated through the implanted nerves. The sciatic nerve function and electrophysiological and histomorphological analyses suggest that the xenogeneic nerve graft was statistically indistinguishable from the allogenic nerve graft but slightly inferior to the isograft in supporting the axonal regeneration and functional recovery.

Interleukin-10 conjugated electrospun polycaprolactone (PCL) nanofibre scaffolds for promoting alternatively activated (M2) macrophages around the peripheral nerve in vivo

Macrophages play a key role in tissue regeneration following peripheral nerve injury by preparing the surrounding parenchyma for regeneration, however, they can be damaging if the response is excessive. Interleukin 10 (IL-10) is a cytokine that promotes macrophages toward an anti-inflammatory/wound healing state (M2 phenotype). The bioactive half-life of IL-10 is dependent on the cellular microenvironment and ranges from minutes to hours in vivo. Our objective was to extend the in vivo bioavailability and bioactivity of IL-10 by attaching the protein onto nanofibrous scaffolds and demonstrating increased expression levels of M2 macrophages when placed around healthy intact peripheral nerves. IL-10 was adsorbed and covalently bound to electrospun poly(ε-caprolactone) (PCL) nanofibrous scaffolds. In vivo bioavailability and bioactivity of IL-10 was confirmed by wrapping IL-10 conjugated nanofibres around the sciatic nerves of Wistar rats and quantifying M2 macrophages immunohistochemically double labelled with ED1 and either arginase 1 or CD206. IL-10 remained immobilised to PCL scaffolds for more than 120days when stored in phosphate buffered saline at room temperature and for up to 14days when implanted around the sciatic nerve. IL-10 conjugated nanofibres successfully induced macrophage polarisation towards the M2 activated state within the scaffold material as well as the adjacent tissue surrounding the nerve. PCL biofunctionalised nanofibres are useful for manipulating the cellular microenvironment. Materials such as these could potentially lead to new therapeutic strategies for nervous tissue injuries as well as provide novel investigative tools for biological research.

Essential oil of Croton zehntneri and its main constituent anethole block excitability of rat peripheral nerve.

Croton zehntneri is an aromatic plant native to Northeast Brazil and employed by local people to treat various diseases. The leaves of this plant have a rich content of essential oil. The essential oil of C. zehntneri samples, with anethole as the major constituent and anethole itself, have been reported to have several pharmacological activities such as antispasmodic, cardiovascular, and gastroprotective effects and inducing the blockade of neuromuscular transmission and antinociception. Since several works have demonstrated that essential oils and their constituents block cell excitability and in view of the multiple effects of C. zehntneri essential oil and anethole on biological tissues, we undertook this investigation aiming to characterize and compare the effects of this essential oil and its major constituent on nerve excitability. Sciatic nerves of Wistar rats were used. They were mounted in a moist chamber, and evoked compound action potentials were recorded. Nerves were exposed in vitro to the essential oil of C. zehntneri and anethole (0.1-1 mg/mL) up to 180 min, and alterations in excitability (rheobase and chronaxie) and conductibility (peak-to-peak amplitude and conduction velocity) parameters of the compound action potentials were evaluated. The essential oil of C. zehntneri and anethole blocked, in a concentration-dependent manner with similar pharmacological potencies (IC50: 0.32 ± 0.07 and 0.22 ± 0.11 mg/mL, respectively), rat sciatic nerve compound action potentials. Strength-duration curves for both agents were shifted upward and to the right compared to the control curve, and the rheobase and chronaxie were increased following essential oil and anethole exposure. The time courses of the essential oil of C. zehntneri and anethole effects on peak-to-peak amplitude of compound action potentials followed an exponential decay and reached a steady state. The essential oil of C. zehntneri and anethole caused a similar reduction in conduction velocities of the compound action potential waves investigated. In conclusion, we demonstrated here that the essential oil of C. zehntneri blocks neuronal excitability and that this effect, which can be predominantly attributable to its major constituent, anethole, is important since these agents have several pharmacological effects likely related to the alteration of excitability. This finding is relevant due to the use of essential oils in aromatherapy and the low acute toxicity of this agent, which exhibits other effects of potential therapeutic usefulness.

Morphological and morphometric analyses of crushed sciatic nerves after application of a purified protein from natural latex and hyaluronic acid hydrogel

Hyaluronic acid hydrogels (HAHs) have been used as a carrier of substances and factors in the repair of nervous tissue. Natural latex protein (Hevea brasiliensis, F1) has shown positive effects in treating various types of tissues, including peripheral nerves. This study evaluated the F1 associated with a HAH in a controlled crush injury (axonotmesis) of the sciatic nerve in Wistar rats. The samples were photomicrographed for morphometric and quantitative analyzes using ImageJ 1.47k software (NIH, Bethesda, MD). Morphological, quantitative (myelin area/nerve area ratio and capillary density) and morphometric (minimum nerve fiber diameter, G-Ratio) data revealed an improvement in the recovery of the sciatic nerve with the application of HAH and the combination of HAH and F1 after 4 and 8 weeks of nerve injury. The most efficacious results were observed with the combination of both substances, F1 and HAH, revealing the regenerative capacity of this new biomaterial, which was hardly tested on nerve tissue.

Inhibition of intracellular signaling pathways NF-κB and MEK1/2 attenuates neuropathic pain development and enhances morphine analgesia

BackgroundNeuropathic pain is clinically challenging because it is resistant to alleviation by morphine. The nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways may be involved in the development of neuropathic pain. The aim of our study was to examine the influence of a chronic, intrathecal administration of parthenolide (PTL, inhibitor of NF-κB) and U0126 (inhibitor of MEK1/2) on nociception and morphine effectiveness in a rat model of neuropathy. MethodsThe chronic constriction injury of the sciatic nerve in Wistar rats was performed. PTL and U0126 were injected chronic intrathecally and morphine was injected once at day 7. To evaluate allodynia and hyperalgesia, the von Frey and cold plate tests were used, respectively. The experiments were carried out according to IASP rules. Using qRT-PCR we analyzed mRNAs of μ-(mor), δ-(dor) and κ-(kor)-opioid receptors in the lumbar spinal cord after drugs administration. ResultsThe administration of PTL and U0126 decreased allodynia and hyperalgesia and significantly potentiated morphine effect. The mor, dor and kor mRNAs were down-regulated 7 days after injury in the ipsilateral spinal cord. The PTL and U0126 significantly up-regulated the mRNA levels of all opioid receptors. The levels of mor and dor mRNAs were much higher compared to those in naïve, but only the kor levels returned to control values. ConclusionsThese results indicate that the inhibition of the NF-κB pathway has better analgesic effects. Both inhibitors similarly potentiate morphine analgesia, which parallels the up-regulation of both mor and dor mRNAs expression spinal levels of the model of neuropathy.

Development of Dissociated Cells from Different CNS Rudiments in Rats after Transplantation into Injured Nerve

The aim of the present work was to identify the potential for implantation of dissociated embryonic spinal cord and neocortex rudiment cells into the sciatic nerve of Wistar rats and to study their differentiation. Cell suspensions prepared by dissociation of fragments of the cervical segment of the spinal cord and anterior cerebral vesicle of rat fetuses at 15 days of development were injected into the proximal segment of previously injured sciatic nerve. Studies using the immunohistochemical marker for stem/progenitor cells (Msi-1) showed that implanted cells could be identified in nerve trunks one day after surgery. At 21 days, some were fully differentiated into NeuN-immunopositive neurons, though the numbers of these cells were small. Most cells in neocortical transplants, in contrast to those of spinal cord transplants, were ependymocytes at 21 days after surgery.

Enhancement of nerve healing with the combined use of amniotic membrane and granulocyte-colony-stimulating factor

Healing of a transected nerve is not always optimal even if it is repaired with an ideal microsurgical technique. We studied the effects of solitary and combined usage of amniotic membrane (AM) wrapping and granulocyte-colony-stimulating factor (GCSF) injections after primary repairs of transected sciatic nerves of Wistar rats. No repair was performed in group 1, primary nerve repairs were performed in group 2, AMs were wrapped around repair sites in group 3, in addition to AM wrapping G-CSF injections were performed in group 4, and only G-CSF injections were performed in group 5. Nerve regeneration was assessed by clinical tests at the 4th, 8th, and 12th weeks and by electrophysiological studies and histological evaluations at the end of the 12th week. Group 4 rats gave earlier responses to clinical tests that showed a stable increase throughout the study. In electrophysiological studies, the mean amplitude values were higher in group 4 whereas mean latency and duration values were higher in group 1. At the end of the 12th week, the morphology of the distal nerve segment was similar to healthy nerves in the absence of fibrosis in group 4. The comparison of mean scores of axonal counting under the light microscope revealed that scores of group 4 were higher than the other groups in a statistically significant manner. Electron microscopy revealed that samples from groups 3 and 4 had high numbers of axons possessing myelin sheaths of normal thickness, as well as less inter-axonal fibrosis. In terms of both axonal diameter and myelin thickness, groups 2, 3, and 4 had higher values than groups 1 and 5. As a conclusion, both AM wrapping and G-CSF injection have a supportive effect on nerve regeneration, and this effect is further potentialized by their combined use.

Axonal Loss in Murine Peripheral Nerves Following Exposure to Recombinant Human Bone Morphogenetic Protein-2 in an Absorbable Collagen Sponge

With the proven efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2) to treat open tibial fractures and promote spine fusion, there has been an increase in its off-label use. Recent studies have shown that BMPs play a role in nerve development and regeneration. Little is known about changes that result when rhBMP-2 is used in the vicinity of peripheral nerves. The purpose of this study is to characterize changes in peripheral nerves following exposure to rhBMP-2-soaked collagen sponges. rhBMP-2 on an absorbable collagen sponge (ACS) was implanted directly on the sciatic nerves of Wistar rats. One and three weeks following surgery, the nerves were harvested and histological analysis was performed to evaluate inflammatory and structural changes. rhBMP-2-soaked collagen sponges induced ectopic bone formation in muscle tissue in all animals after three weeks, but did not cause bone formation within the nerve. Axonal swelling and splitting of the myelin sheath were observed in both experimental and control nerves and may be a result of surgical manipulation. The overall incidence of axonal loss was 15.8% in the rhBMP-2/ACS-exposed nerves and was 0% in control nerves (p < 0.05). rhBMP-2-soaked collagen sponges may adversely affect the axons of peripheral nerves by causing axonal dropout and loss of axons. Ectopic bone formation occurs within muscle tissues and not within the peripheral nerve. The axonal dropout may be a direct effect of rhBMP-2-soaked collagen sponges and not nerve compression as it was observed prior to ectopic bone formation.

Preparation and evaluation of NGF-microsphere conduits for regeneration of defective nerves

Objectives: To fabricate nerve growth factor (NGF) microsphere conduits and evaluate their promotional effects on regeneration of defective nerves.Methods: NGF microspheres containing ovalbumin were prepared using a double-emulsion method. The total amount of NGF was determined by enzyme-linked immunosorbent assay, and bioactive NGF was quantified by the PC12 cell line method; the NGF bioactivity present during the release period was monitored. Conduits made of polylacticacid were added to the NGF microspheres to bridge and repair the nerve injury. The sciatic nerve of Wistar rats was used to evaluate nerve-regeneration efficacy.Results: NGF microspheres were spherical, with smooth and compact surfaces. The fabrication yield, encapsulation efficiency, and drug loading of the microspheres were 58·3, 29·72, and 0·003%, respectively. The monitoring of NGF bioactivity remaining during the release period showed that ∼40% of the original bioactivity was kept on the twenty-eighth day and 10% left on the ninetieth day. Polylacticacid conduits are lowly antigenic, porous (facilitates oxygen diffusion), and able to prevent long-term compression. After 15 days, the length of nerve regenerated from NGF-microsphere conduits was statistically different from that of the control groups (P<0·05). NGF microspheres can accelerate the early nerve-regeneration rate, although the rate was not as good as that caused by autografts. Three months later, the recovery rate of the regenerated nerve collected from NGF-microsphere conduits showed lower values of nerve-conduction velocity, muscular tension, and muscle weight. However, poorer rates of regeneration were observed in the self-mutilation foot compared with those of the control group. The control group had no statistical difference from the sodium chloride and NGF-solution conduits, the best in the autograft group.Discussion: A long-term promoting effect of microsphere-bound exogenous NGF on the functional repair of peripheral nerves could not be confirmed, although the nerve-regeneration rate was rapid in the early stage. Better methods are needed to incorporate protein-release systems into nerve conduits to improve functional recovery in patients with injured nerves.