Vatalanib decrease the positive interaction of VEGF receptor-2 and P2X(2/3) receptor in chronic constriction injury rats

Neuropathic pain can arise from a lesion affecting the peripheral nervous system. Selective P2X(3) and P2X(2/3) receptors' antagonists effectively reduce neuropathic pain. VEGF inhibitors are effective for pain relief. The present study investigated the effects of Vatalanib (VEGF receptor-2 (VEGFR-2) inhibitor) on the neuropathic pain to address the interaction of VEGFR-2 and P2X(2/3) receptor in dorsal root ganglia of chronic constriction injury (CCI) rats. Neuropathic pain symptoms following CCI are similar to most peripheral lesions as assessed by the Neuropathic Pain Symptom Inventory. Sprague-Dawley rats were randomly divided into sham group, CCI group and CCI rats treated with Vatalanib group. Mechanical withdrawal threshold and thermal withdrawal latency were measured. Co-expression of VEGFR-2 and P2X(2) or P2X(3) in L4-6 dorsal root ganglia (DRG) was detected by double-label immunofluorescence. The modulation effect of VEGF on P2X(2/3) receptor agonist-activated currents in freshly isolated DRG neurons of rats both of sham and CCI rats was recorded by whole-cell patch-clamp technique. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in CCI group were lower than those in sham group (p<0.05). MWT and TWL in CCI rats treated with Vatalanib group were increased compared with those in CCI group (p<0.05). VEGFR-2 and P2X(2) or P2X(3) receptors were co-expressed in the cytoplasm and surface membranes of DRG. The co-expression of VEGFR-2 and P2X(2) or P2X(3) receptor in CCI group exhibited more intense staining than those in sham group and CCI rats treated with Vatalanib group, respectively. VEGF enhanced the amplitude of ATP and α,β-meATP -activated currents of both sham and CCI rats. Increment effects of VEGF on ATP and α,β-meATP -activated currents in CCI rats were higher than those in sham rats. Both ATP (100 μM) and α,β-meATP (10 μM)- activated currents enhanced by VEGF ( 1nM) were significantly blocked by Vatalanib (1 μM, an inhibitor of VEGF receptors). The stain values of VEGFR-2, P2X(2) and P2X(3) protein expression in L4/5 DRG of CCI treated with Vatalanib group were significantly decreased compared with those in CCI group (p<0.01). Vatalanib can alleviate chronic neuropathic pain by decreasing the activation of VEGF on VEGFR-2 and the positive interaction between the up-regulated VEGFR-2 and P2X(2/3) receptors in the neuropathic pain signaling.     

Effect of lappaconitine on neuropathic pain mediated by P2X3 receptor in rat dorsal root ganglion

ATP facilitates initiation and transmission of the neuropathic pain at the dorsal root ganglion (DRG) level via the P2X receptors, especially the subtype P2X(3). Lappaconitine (LA) is an active principle isolated from Chinese herbal medicine and possesses analgesic effect. The aim of this study was to investigate the effect of LA on chronic constriction injury (CCI)-induced neuropathic pain mediated by P2X(3) receptor in the DRG neurons. In the presence of CCI and/or LA, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured and P2X(3) receptor expression in the DRG neurons was evaluated by immunohistochemistry and Western blotting. Following intrathecal administration of P2X(3) receptor oligonucleotide, the effect of LA on pain thresholds was assessed. Furthermore, the effect of LA on the P2X(3) receptor agonists ATP- and α,β-meATP-induced inward currents (I(ATP) and I(α,β-meATP)) in the acutely dissociated rat DRG neurons was investigated by whole cell patch-clamp. The results included: (1) There showed reduction of pain thresholds, enhancement of I(ATP) and I(α,β-meATP) and up-regulation of P2X(3) receptor expression in rat DRG neurons when neuropathic pain occurred. (2) In the presence of LA, the decreased pain thresholds, the up-regulated P2X(3) receptor expression and the enhanced I(ATP) and I(α,β-meATP) were reversible in the CCI rats. (3) The down-regulated P2X(3) receptor expression with pretreatment of P2X(3) receptor antisense oligonucleotide significantly attenuated the analgesic effect of LA. These results indicate that the analgesic effect of LA involves decrease of expression and sensitization of the P2X(3) receptors of the rat DRG neurons following CCI.     

Role of sodium ferulate in the nociceptive sensory facilitation of neuropathic pain injury mediated by P2X(3) receptor

Neuropathic pain usually is persistent and no effective treatment. ATP plays an important role in the initiation of pain. P2X(3) receptors are localized in the dorsal root ganglion (DRG) neurons and activated by extracellular ATP. Sodium ferulate (SF) is an active principle from Chinese herbal medicine and has anti-inflammatory activities. This study observed the effects of SF on the nociceptive facilitation of the primary sensory afferent after chronic constriction injury (CCI) mediated by P2X(3) receptor. In this study, the content of ATP in DRG neurons was measured by high-performance liquid chromatography (HPLC). P2X(3) agonist-activated currents in DRG neurons was recorded by the whole-cell patch-clamp skill. The expression of P2X(3) mRNA in DRG neurons was analyzed by in situ hybridization. The ATP content of DRG was increased after CCI. In CCI rats treated with SF, the content of ATP in DRG neurons was reduced. SF decreased the increment of P2X(3) agonist-activated currents and P2X(3) mRNA expression in DRG neurons during CCI. SF may inhibit the initiation of pain and primary afferent sensitization mediated by P2X(3) receptor during CCI.     

Nanoparticle-encapsulated emodin decreases diabetic neuropathic pain probably via a mechanism involving P2X3 receptor in the dorsal root ganglia

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes mellitus (DM). More than 90% of all cases of DM belong to type 2 diabetes mellitus (T2DM). Emodin is the main active component of Radix et rhizoma rhei and has anti-bacterial, anti-viral, anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. Nanoparticle encapsulation of drugs is beneficial for drug targeting and bioavailability as well as for lowering drug toxicity side effects. The aim of this study was to investigate the effects of nanoparticle-encapsulated emodin (nano emodin) on diabetic neuropathic pain (DNP) mediated by the Purin 2X3 (P2X3) receptor in the dorsal root ganglia (DRG). Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) values in T2DM rats were lower than those of control rats. MWT and TWL in T2DM rats treated with nano emodin were higher compared with those in T2DM rats. Expression levels of P2X3 protein and messenger RNA (mRNA) in the DRG of T2DM rats were higher than those of controls, while levels in T2DM rats treated with nano emodin were significantly lower than those of the T2DM rats. Phosphorylation and activation of ERK1/2 in the T2DM DRG were decreased by nano emodin treatment. Nano emodin significantly inhibited currents activated by the P2X3 agonist α,β-meATP in HEK293 cells transfected with the P2X3 receptor. Therefore, nano emodin treatment may relieve DNP by decreasing excitatory transmission mediated by the DRG P2X3 receptor in T2DM rats.     

Suppressing PKC-dependent membrane P2X3 receptor upregulation in dorsal root ganglia mediated electroacupuncture analgesia in rat painful diabetic neuropathy

Painful diabetic neuropathy (PDN) is a common and troublesome diabetes complication. Protein kinase C (PKC)-mediated dorsal root ganglia (DRG) P2X3 receptor upregulation is one important mechanism underlying PDN. Accumulating evidence demonstrated that electroacupuncture (EA) at low frequency could effectively attenuate neuropathic pain. Our previous study showed that 2-Hz EA could relieve pain well in PDN. The study aimed to investigate whether 2-Hz EA relieves pain in PDN through suppressing PKC-mediated DRG P2X3 receptor upregulation. A 7-week feeding of high-fat and high-sugar diet plus a single injection of streptozotocin (STZ) in a dose of 35 mg/kg after a 5-week feeding of the diet successfully induced type 2 PDN in rats as revealed by the elevated body weight, fasting blood glucose, fasting insulin and insulin resistance, and the reduced paw withdrawal threshold (PWT), as well as the destructive ultrastructural change of sciatic nerve. DRG plasma membrane P2X3 receptor level and DRG PKC expression were elevated. Two-hertz EA failed to improve peripheral neuropathy; however, it reduced PWT, DRG plasma membrane P2X3 receptor level, and DRG PKC expression in PDN rats. Intraperitoneal administration of P2X3 receptor agonist αβ-meATP or PKC activator phorbol 12-myristate 13-acetate (PMA) blocked 2-Hz EA analgesia. Furthermore, PMA administration increased DRG plasma membrane P2X3 receptor level in PDN rats subject to 2-Hz EA treatment. These findings together indicated that the analgesic effect of EA in PDN is mediated by suppressing PKC-dependent membrane P2X3 upregulation in DRG. EA at low frequency is a valuable approach for PDN control.     

Electroacupuncture alleviates diabetic neuropathic pain in rats by suppressing P2X3 receptor expression in dorsal root ganglia

Diabetic neuropathic pain (DNP) is a troublesome diabetes complication all over the world. P2X3 receptor (P2X3R), a purinergic receptor from dorsal root ganglion (DRG), has important roles in neuropathic pain pathology and nociceptive sensations. Here, we investigated the involvement of DRG P2X3R and the effect of 2 Hz electroacupuncture (EA) on DNP. We monitored the rats’ body weight, fasting blood glucose level, paw withdrawal thresholds, and paw withdrawal latency, and evaluated P2X3R expression in DRG. We found that P2X3R expression is upregulated on DNP, while 2 Hz EA is analgesic against DNP and suppresses P2X3R expression in DRG. To evaluate P2X3R involvement in pain modulation, we then treated the animals with A317491, a P2X3R specific antagonist, or α β-me ATP, a P2X3R agonist. We found that A317491 alleviates hyperalgesia, while α β-me ATP blocks EA’s analgesic effects. Our findings indicated that 2 Hz EA alleviates DNP, possibly by suppressing P2X3R upregulation in DRG.

     

Functional characterization and analgesic effects of mixed cannabinoid receptor/T-type channel ligands

Background

Increased neuronal excitability and spontaneous firing are hallmark characteristics of injured sensory neurons. Changes in expression of various voltage-gated Na⁺ channels (VGSCs) have been observed under neuropathic conditions and there is evidence for the involvement of protein kinase C (PKC) in sensory hyperexcitability. Here we demonstrate the contribution of PKC to P2X-evoked VGSC activation in dorsal root ganglion (DRG) neurons in neuropathic conditions.

Results

Using the spinal nerve ligation (SNL) model of neuropathic pain and whole-cell patch clamp recordings of dissociated DRG neurons, we examined changes in excitability of sensory neurons after nerve injury and observed that P2X3 purinoceptor-mediated currents induced by α,β-meATP triggered activation of TTX-sensitive VGSCs in neuropathic nociceptors only. Treatment of neuropathic DRGs with the PKC blocker staurosporine or calphostin C decreased the α,β-meATP-induced Na⁺ channels activity and reversed neuronal hypersensitivity. In current clamp mode, α,β-meATP was able to evoke action-potentials more frequently in neuropathic neurons than in controls. Pretreatment with calphostin C significantly decreased the proportion of sensitized neurons that generated action potentials in response to α,β-meATP. Recordings measuring VGSC activity in neuropathic neurons show significant change in amplitude and voltage dependence of sodium currents. In situ hybridization data indicate a dramatic increase in expression of embryonic Na_v1.3 channels in neuropathic DRG neurons. In a CHO cell line stably expressing the Na_v1.3 subunit, PKC inhibition caused both a significant shift in voltage-dependence of the channel in the depolarizing direction and a decrease in current amplitude.

Conclusion

Neuropathic injury causes primary sensory neurons to become hyperexcitable to ATP-evoked P2X receptor-mediated depolarization, a phenotypic switch sensitive to PKC modulation and mediated by increased activity of TTX-sensitive VGSCs. Upregulation in VGSC activity after injury is likely mediated by increased expression of the Na_v1.3 subunit, and the function of the Na_v1.3 channel is regulated by PKC.     

Differential expression of ATP-gated P2X receptors in DRG between chronic neuropathic pain and visceralgia rat models

There are divergences between neuropathic pain and visceralgia in terms of the duration, location, and character of hyperalgesia. It is generally recognized that nociceptive receptors, including P2X receptors, may play different roles in nociceptive mechanisms. The different roles of P2X1–7 receptors have not been fully understood both in neuropathic pain and visceral hyperalgesia. In order to explore the different expressions of P2X1–7 receptors in these two hyperalgesia models, the lumbosacral dorsal root ganglion (DRG) neurons from rat sciatic nerve chronic constriction injury (CCI) model and neonatal colorectal distention (NCRD) model were studied (both the primary nociceptive neuron afferents of those two models projected to the same segment of spinal cord). Both immunohistochemistry (IHC) technique and real-time fluorescence quantitative polymerase chain reaction (RT-PCR) technology were applied to analyze the protein expression levels and nucleic acid of P2X1–7 receptors. We found that except P2X2 and P2X3, the expression levels of P2X1 and P2X5 receptors increased in neuropathic pain while those expression levels of P2X4, P2X6, and P2X7 receptors increased in visceral pain. Our results also suggested that in addition to P2X2/3 heteromeric, other P2X subunits may also involved in generation heteromeric such as P2X1/5 and/or P2X2/5 in neuropathic pain and P2X4/6 and/or P2X4/7 in visceral pain.     

An Evaluation of the Antinociceptive Effects of Phα1β, a Neurotoxin from the Spider Phoneutria nigriventer, and ω-Conotoxin MVIIA, a Cone Snail Conus magus Toxin, in Rat Model of Inflammatory and Neuropathic Pain

Voltage-sensitive calcium channels (VSCCs) underlie cell excitability and are involved in the mechanisms that generate and maintain neuropathic and inflammatory pain. We evaluated in rats the effects of two VSCC blockers, ω-conotoxin MVIIA and Phα1β, in models of inflammatory and neuropathic pain induced with complete Freund’s adjuvant (CFA) and chronic constrictive injury (CCI), respectively. We also evaluated the effects of the toxins on capsaicin-induced Ca²⁺ influx in dorsal root ganglion (DRG) neurons obtained from rats exposed to both models of pain. A single intrathecal injection of Phα1β reversibly inhibits CFA and CCI-induced mechanical hyperalgesia longer than a single injection of ω-conotoxin MVIIA. Phα1β and MVIIA also inhibited capsaicin-induced Ca²⁺ influx in DRG neurons. The inhibitory effect of Phα1β on capsaicin-induced calcium transients in DRG neurons was greater in the CFA model of pain, while the inhibitory effect of ω-conotoxin MVIIA was greater in the CCI model. The management of chronic inflammatory and neuropathic pain is still a major challenge for clinicians. Phα1β, a reversible inhibitor of VSCCs with a preference for N-type Ca²⁺ channels, has potential as a novel therapeutic agent for inflammatory and neuropathic pain. Clinical studies are necessary to establish the role of Phα1β in the treatment of chronic pain.     

脊髓自噬功能激活与大鼠2型糖尿病神经病理性疼痛的关系

目的：探讨脊髓自噬功能与大鼠2型糖尿病神经病理性疼痛（DNP）的关系。方法：雄性SD大鼠（42只）高糖高脂饲养8周,腹腔单次注射链脲佐菌素（STZ）制备大鼠2型糖尿病模型。两周后检测机械缩足阈值（MWT）和热缩足潜伏期（TWL）,降至基础值80%以下者为2型糖尿病神经病理性疼痛大鼠,记为DNP组（24只）;未降至基础值80%以下者为2型糖尿病无神经病理性疼痛大鼠,记为DA组（18只）。另取18只大鼠为对照（control,C）组,普通饲料喂养。于确定DA与DNP分组后的第3、7和14天,测定机械缩足阈值（MWT）和热缩足潜伏期（TWL）,并在行为学检测结束后各组随机取6只大鼠处死,取L4~L6脊髓膨大,采用Western blot法检测自噬特异性蛋白微管相关蛋白1（Beclin-1）、微管相关蛋白1轻链3（LC3）和P62的表达。另取6只7 d DNP组大鼠采用免疫荧光双染法检测脊髓背角P62与小胶质细胞、星形胶质细胞、神经元的共表达情况。结果：连续8周喂养高糖高脂饲料的SD大鼠的血浆胰岛素水平升高,胰岛素敏感指数下调,表明出现胰岛素抵抗;在腹腔注射STZ后,血糖升高达到2型糖尿病诊断标准（≥16.7 mmol/L）;与C组、DA组比较,DNP组大鼠在第3、7和14天时MWT降低,TWL缩短,并且脊髓背角LC3-Ⅱ、Beclin-1表达上调,P62表达下降（P<0.05）。免疫荧光双染色显示,P62在脊髓背角表达,主要与神经元共存,少量与小胶质细胞共存,几乎不与星形胶质细胞共表达。结论：2型糖尿病神经病理性疼痛大鼠脊髓LC3-Ⅱ、Beclin-1和P62表达的改变提示脊髓自噬功能激活;脊髓背角中神经元自噬激活在2型糖尿病大鼠DNP的发生和发展起着关键作用。     

AMPA and NMDA glutamate receptors are found in both peptidergic and non-peptidergic primary afferent neurons in the rat

Two distinct classes of nociceptive primary afferents, peptidergic and non-peptidergic, respond similarly to acute noxious stimulation; however the peptidergic afferents are more likely to play a role in inflammatory pain, while the non-peptidergic afferents may be more characteristically involved in neuropathic pain. Using multiple immunofluorescence, we determined the proportions of neurons in the rat L4 dorsal root ganglion (DRG) that co-express AMPA or NMDA glutamate receptors and markers for the peptidergic and non-peptidergic classes of primary afferents, substance P and P2X(3), respectively. The fraction of DRG neurons immunostained for the NR1 subunit of the NMDA receptor (40%) was significantly higher than that of DRG neurons immunostained for the GluR2/3 (27%) or the GluR4 (34%) subunits of the AMPA receptor. Of all DRG neurons double-immunostained for glutamate receptor subunits and either marker for peptidergic and non-peptidergic afferents, a significantly larger proportion expressed GluR4 than GluR2/3 or NR1 and in a significantly larger proportion of P2X(3)- than SP-positive DRG neurons. These observations support the idea that nociceptors, involved primarily in the mediation of neuropathic pain, may be presynaptically modulated by GluR4-containing AMPA receptors.     

The effect of sinomenine in diabetic neuropathic pain mediated by the P2X<Subscript>3</Subscript> receptor in dorsal root ganglia

Type 2 diabetes mellitus (T2DM) accounts for more than 90% of all cases of diabetes mellitus (DM). Diabetic neuropathic pain (DNP) is a common complication of T2DM. Sinomenine is a natural bioactive component extracted from the Sinomenium acutum and has anti-inflammatory effects. The aim of our study was to investigate the effects of sinomenine on DNP mediated by the P2X₃ receptor in dorsal root ganglia (DRG). The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in T2DM rats were lower than those of control rats. MWT and TWL in T2DM rats treated with sinomenine were higher compared with those in T2DM rats. The expression levels of the P2X₃ protein and mRNA in T2DM rat DRG were higher compared with those of the control, while those in T2DM rats treated with sinomenine were significantly lower compared with those of the T2DM rats. Sinomenine significantly inhibited P2X₃ agonist ATP-activated currents in HEK293 cells transfected with the P2X₃ receptor. Sinomenine decreased the phosphorylation and activation of P38MAPK in T2DM DRG. Therefore, sinomenine treatment may suppress the up-regulated expression and activation of the P2X₃ receptor and relieve the hyperalgesia potentiated by the activation of P38MAPK in T2DM rats.     

MiR‐101 promotes pain hypersensitivity in rats with chronic constriction injury via the MKP‐1 mediated MAPK pathway

This study was performed to characterize the effect of microRNA‐101 (miR‐101) on the pain hypersensitivity in CCI rat models with the involvement of mitogen‐activated protein kinase phosphatase 1 (MKP‐1) in spinal cord microglial cells. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in the developed CCI models were determined to assess the hypersensitivity of rats to mechanical stimulation and thermal pain. To assess inflammation, the levels of interleukin (IL)‐1β, IL‐6 and tumour necrosis factor‐α (TNF‐α) in the spinal dorsal horns of CCI rats and lipopolysaccharide (LPS)‐activated microglial cells were examined. miR‐101 and MKP‐1 gain‐ and loss‐of‐function experiments were conducted in in vivo and in vitro settings to examine the roles of miR‐101 and MKP‐1 in CCI hypersensitivity and inflammation. The results showed that miR‐101 was highly expressed in the spinal dorsal horn and microglial cells of CCI rat models. Furthermore, overexpression of miR‐101 promoted the pain hypersensitivity in CCI rat models by reducing MWT and TWL. The overexpression of miR‐101 also promoted inflammation in LPS‐exposed microglial cells, as indicated by increased levels of IL‐1β, IL‐6 and TNF‐α. MiR‐101 was shown to target MKP‐1, inhibiting its expression. Moreover, miR‐101 promoted pain hypersensitivity in CCI rat models by inhibiting MKP‐1 expression and activating the mitogen‐activated protein kinase (MAPK) signalling pathway. Taken together, miR‐101 could potentially promote hypersensitivity and inflammatory response of microglial cells and aggravate neuropathic pain in CCI rat models by inhibiting MKP‐1 in the MAPK signalling pathway.     

ATP receptors in pain sensation: Involvement of spinal microglia and P2X<Subscript>4</Subscript> receptors

There is abundant evidence that extracellular ATP and other nucleotides have an important role in pain signaling at both the periphery and in the CNS. At first, it was thought that ATP was simply involved in acute pain, since ATP is released from damaged cells and excites directly primary sensory neurons by activating their receptors. However, neither blocking P2X/Y receptors pharmacologically nor suppressing the expression of P2X/Y receptors molecularly in sensory neurons or in the spinal cord had an effect on acute physiological pain. The focus of attention now is on the possibility that endogenous ATP and its receptor system might be activated in pathological pain states, particularly in neuropathic pain. Neuropathic pain is often a consequence of nerve injury through surgery, bone compression, diabetes or infection. This type of pain can be so severe that even light touching can be intensely painful; unfortunately, this state is generally resistant to currently available treatments. An important advance in our understanding of the mechanisms involved in neuropathic pain has been made by a recent work demonstrating the crucial role of ATP receptors (i.e., P2X₃ and P2X₄ receptors). In this review, we summarize the role of ATP receptors, particularly the P2X₄ receptor, in neuropathic pain. The expression of P2X₄ receptors in the spinal cord is enhanced in spinal microglia after peripheral nerve injury, and blocking pharmacologically and suppressing molecularly P2X₄ receptors produce a reduction of the neuropathic pain behaviour. Understanding the key roles of ATP receptors including P2X₄ receptors may lead to new strategies for the management of neuropathic pain.     

P2X receptors-mediated cytosolic phospholipase A2 activation in primary afferent sensory neurons contributes to neuropathic pain

Activation of P2X₃ and P2X_2/3 receptors (P2X₃R/P2X_2/3R), ionotropic ATP receptor subtypes, in primary sensory neurons is involved in neuropathic pain, a debilitating chronic pain that occurs after peripheral nerve injury. However, the underlying mechanisms remain unknown. We investigated the role of cytosolic phospholipase A₂ (cPLA₂) as a downstream molecule that mediates the P2X₃R/P2X_2/3R-dependent neuropathic pain. We found that applying ATP to cultured dorsal root ganglion (DRG) neurons increased the level of Ser505-phosphorylated cPLA₂ and caused translocation of Ser505-phosphorylated cPLA₂ to the plasma membrane. The ATP-induced cPLA₂ activation was inhibited by a selective antagonist of P2X₃R/P2X_2/3R and by a selective inhibitor of cPLA₂. In the DRG in vivo , the number of cPLA₂-activated neurons was strikingly increased after peripheral nerve injury but not after peripheral inflammation produced by complete Freund's adjuvant. Pharmacological blockade of P2X₃R/P2X_2/3R reversed the nerve injury-induced cPLA₂ activation in DRG neurons. Moreover, administering the cPLA₂ inhibitor near the DRG suppressed nerve injury-induced tactile allodynia, a hallmark of neuropathic pain. Our results suggest that P2X₃R/P2X_2/3R-dependent cPLA₂ activity in primary sensory neurons is a key event in neuropathic pain and that cPLA₂ might be a potential target for treating neuropathic pain.     

Intrathecal NGF Administration Reduces Reactive Astrocytosis and Changes Neurotrophin Receptors Expression Pattern in a Rat Model of Neuropathic Pain

Nerve growth factor (NGF), an essential peptide for sensory neurons, seems to have opposite effects when administered peripherally or directly to the central nervous system. We investigated the effects of 7-days intrathecal (i.t.) infusion of NGF on neuronal and glial spinal markers relevant to neuropathic behavior induced by chronic constriction injury (CCI) of the sciatic nerve. Allodynic and hyperalgesic behaviors were investigated by Von Frey and thermal Plantar tests, respectively. NGF-treated animals showed reduced allodynia and thermal hyperalgesia, compared to control animals. We evaluated on lumbar spinal cord the expression of microglial (ED-1), astrocytic (GFAP and S-100β), and C- and Aδ-fibers (SubP, IB-4 and Cb) markers. I.t. NGF treatment reduced reactive astrocytosis and the density of SubP, IB4 and Cb positive fibers in the dorsal horn of injured animals. Morphometric parameters of proximal sciatic nerve stump fibers and cells in DRG were also analyzed in CCI rats: myelin thickness was reduced and DRG neurons and satellite cells appeared hypertrophic. I.t. NGF treatment showed a beneficial effect in reversing these molecular and morphological alterations. Finally, we analyzed by immunohistochemistry the expression pattern of neurotrophin receptors TrkA, pTrkA, TrkB and p75^NTR. Substantial alterations in neurotrophin receptors expression were observed in the spinal cord of CCI and NGF-treated animals. Our results indicate that i.t. NGF administration reverses the neuro-glial morphomolecular changes occurring in neuropathic animals paralleled by alterations in neurotrophin receptors ratio, and suggest that NGF is effective in restoring homeostatic conditions in the spinal cord and maintaining analgesia in neuropathic pain.