Effect of Nimodipine and Botulinum Toxin A on Peripheral Nerve Regeneration in Rats: A Pilot Study.

BACKGROUND: Peripheral nerve damage is a frequent problem, with an estimated 2.8%-5.0% of trauma admissions involving peripheral nerve injury. End-to-end, tension-free microsurgical repair (neurorrhaphy) is the current gold standard treatment for complete transection (neurotmesis). While neurorrhaphy reapproximates the nerve, it does not address the complex molecular regenerative process. Evidence suggests that botulinum toxin A (BTX) and nimodipine (NDP) may improve functional recovery, but mechanisms of action remain unknown. METHODS: This research investigates BTX and NDP for their novel capacity to improve neural regeneration in the setting of neurorrhaphy using a Lewis rat tibial nerve neurotmesis model. In a triple-masked, placebo-controlled, randomized study design, we compared functional (rotarod, horizontal ladder walk), electrophysiological (conduction velocity, duration), and stereological (axon count, density) outcomes of rats treated with: NDP+saline injection, BTX+NDP, Saline+placebo, and BTX+placebo. Additional controls included sham surgery +/- BTX. RESULTS: NDP+saline outperformed other treatment groups in the ladder walk. This group had the fewest deep slips (15.07% versus 30.77% in BTX+NDP, P = 0.122), and the most correct steps (70.53% versus 55.58% in BTX+NDP, P = 0.149) in functional testing. NDP+saline also had the fastest nerve conduction velocity (0.811m/s versus 0.598m/s in BTX+NDP, P = 0.126) among treatment groups. BTX+NDP had the highest axon count (10,012.36 versus 7,738.18 in NDP+Saline, P = 0.009). CONCLUSION: This study is the first to test NDP with BTX in a multimodal assessment of nerve recovery following neurotmesis and neurorrhaphy. NDP outperformed BTX+NDP functionally. Future work will focus on nimodipine in an effort to improve nerve recovery in trauma patients.

[A meta-analysis of the effect of occupational exposure to 1-bromopropane on workers' nerve conduction velocity].

Objective: To analysis the occupational exposure to 1-bromopropane on the worker's nerve conduc-tion velocity. Methods: To PubMed, Wanfang, VIP, Chinese Journal Full-text Database (CNKI) and other databases as a data source, searched and screened database to October 2017 on occupational exposure to 1-bromopropane workers on the role of nerve conduction in the paper. According to inclusion and exclusion criteria, we screened literatures, extracted data and evaluated the quality of the included studies, using RevMan5.3 software to test the heterogeneity of the results and us-ing the corresponding mathematical model for data combination analysis. Results: A total of 5 articles were included in the literature. The results showed that the tibial nerve MCV of workers in the 1-bromopropane exposure group was slower than that in the control group (SMD=-0.47,95%CI=-0.70~-0.24) , the difference was statistically significant (Z=4.06, P<0.01). The tibial nerve DL of the exposure group was more prolonged than that of the control group (SMD=0.35,95%CI=0.00~0.69) , with a statistically significant difference (Z=1.99, P=0.05). The sural nerve SCV of the exposure group was slower than that of the control group (SMD=-0.47, 95%CI=-0.78~-0.15), with a statistically significant difference (Z=2.88,P<0.01). Conclusion: Occupational exposure to 1-bromopropane may have an effect on the worker's nerve conduction ve-locity.It's necessary to do broader and deeper neurotoxicity studies about 1-bromopropane.

Antiallodynic Effects of Endomorphin-1 and Endomorphin-2 in the Spared Nerve Injury Model of Neuropathic Pain in Mice.

BACKGROUND: The spared nerve injury (SNI) model is a new animal model that can mimic several characteristics of clinical neuropathic pain. Opioids are recommended as treatment of neuropathic pain. Therefore, the present study was conducted to investigate the antinociceptive effects of endomorphin-1 (EM-1) and endomorphin-2 (EM-2) given centrally and peripherally in the SNI model of neuropathic pain in mice. METHODS: The SNI model was made in mice by sparing the sural nerve intact, when the other 2 of 3 terminal branches of the sciatic nerve (common peroneal and tibial nerves) were tightly ligated and cut. Von Frey monofilaments were used to measure the SNI-induced mechanical allodynia-like behavior. The antiallodynic effects of EM-1 and EM-2 were determined after central and peripheral administration in the SNI model of neuropathic pain. Also, the specific opioid receptor antagonists were used to determine the opioid mechanisms of EMs involved in neuropathic pain. Values were expressed as the mean ± standard deviation. RESULTS: Our results showed that the SNI mice developed prolonged mechanical allodynia-like behavior in ipsilateral paw after surgery, with the withdrawal threshold value being 0.061 ± 0.02 g after 14 days. EM-1 and EM-2 produced significant antiallodynic effects in ipsilateral paw after intracerebroventricular (i.c.v.) administration, more effective than that of morphine. The peak withdrawal thresholds of 10 nmol EM-1 and EM-2 determined at 5 minutes after injection were 0.92 ± 0.36 and 0.87 ± 0.33 g, respectively, higher than that of morphine (0.46 ± 0.20 g). Moreover, both EMs (10 nmol, i.c.v.) exerted significant antiallodynic effects in the contralateral paw, whereas no significant antinociceptive activity was seen after i.c.v. administration of morphine with equimolar dose. It was noteworthy that EM-1 and EM-2 produced antinociception through distinct µ1- and µ2-opioid receptor subtypes, and the EM-2-induced antiallodynia contained an additional component that was mediated by the release of endogenous dynorphin A, acting on κ-opioid receptor. In addition, the antiallodynic activities of peripheral administration of EM-1, EM-2, and morphine were also investigated. Intraplantar, but not subcutaneous administration of EM-1 and EM-2 also exhibited potent antinociception, establishing the peripheral and local effects. Both µ1- and µ2-opioid receptor subtypes, but not the δ- or κ-opioid receptors were involved in the peripheral antiallodynia of EMs. CONCLUSIONS: The present investigation demonstrated that both EM-1 and EM-2 given centrally and peripherally produced potent antiallodynic activities in SNI mice, and differential opioid mechanisms were involved.

Tibial Nerve Block Using an Ultrasound-Guided Inframalleolar Medial Plantar Nerve Perineural Injection: A Technical Note.

Sonographic-guided tibial nerve block allows for rapid anesthetization of the heel and plantar regions of the foot. We describe a variant technique for tibial nerve regional anesthesia utilizing perineural injection of the medial plantar nerve proximal to the sustentaculum tali where the nerve is superficial and readily accessed, with resultant retrograde flow of local anesthetic proximally. Perineural injection of the medial plantar nerve at the inframalleolar level provides a simple, safe, and effective alternative method to achieve tibial nerve block for regional anesthesia in a variety of procedures. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:134-137, 2017.

Diabetic neuropathy increases stimulation threshold during popliteal sciatic nerve block.

BACKGROUND: Peripheral nerve stimulation is commonly used for nerve localization in regional anaesthesia, but recommended stimulation currents of 0.3-0.5 mA do not reliably produce motor activity in the absence of intraneural needle placement. As this may be particularly true in patients with diabetic neuropathy, we examined the stimulation threshold in patients with and without diabetes. METHODS: Preoperative evaluation included a neurological exam and electroneurography. During ultrasound-guided popliteal sciatic nerve block, we measured the current required to produce motor activity for the tibial and common peroneal nerve in diabetic and non-diabetic patients. Proximity to the nerve was evaluated post-hoc using ultrasound imaging. RESULTS: Average stimulation currents did not differ between diabetic (n=55) and non-diabetic patients (n=52). Although the planned number of patients was not reached, the power goal for the mean stimulation current was met. Subjects with diminished pressure perception showed increased thresholds for the common peroneal nerve (median 1.30 vs. 0.57 mA in subjects with normal perception, P=0.042), as did subjects with decreased pain sensation (1.60 vs. 0.50 mA in subjects with normal sensation, P=0.038). Slowed ulnar nerve conduction velocity predicted elevated mean stimulation current (r=-0.35, P=0.002). Finally, 15 diabetic patients required more than 0.5 mA to evoke a motor response, despite intraneural needle placement (n=4), or required currents ≥2 mA despite needle-nerve contact, vs three such patients (1 intraneural, 2 with ≥2 mA) among non-diabetic patients (P=0.003). CONCLUSIONS: These findings suggest that stimulation thresholds of 0.3-0.5 mA may not reliably determine close needle-nerve contact during popliteal sciatic nerve block, particularly in patients with diabetic neuropathy. CLINICAL TRIAL REGISTRATION: NCT01488474.

The local effect of octreotide on mechanical pain sensitivity is more sensitive in DA rats than DA.1U rats.

A recent study by the authors indicated that major histocompatibility complex (MHC) genes are associated with the differences in basal pain sensitivity and in formalin model between Dark-Agouti (DA) and novel congenic DA.1U rats, which have the same genetic background as DA rats except for the u alleles of MHC. The objective of the present study is to investigate whether there is a difference in the pristane-induced arthritis (PIA) model and local analgesic effect of octreotide (OCT) between DA and DA.1U rats. The hindpaw mechanical withdrawal threshold (MWT) and heat withdrawal latency (HWL) were observed. The C unit firings of the tibial nerve evoked by non-noxious and noxious toe movements were recorded by electrophysiological methods in normal and PIA models in DA and DA.1U rats before and after local OCT administration. The expression of somatostatin receptor 2A (SSTR2A) was observed by immunohistochemistry. The results demonstrate that DA rats have a higher mechanical sensitivity than DA.1U rats after PIA. Local OCT administration significantly elevated MWT in DA rats under normal and PIA sate, but not in DA.1U rats. The electrophysiological experiments showed OCT significantly attenuated the firings of C units evoked by non-noxious and noxious stimulation in DA rats more than those in DA.1U rats both in normal and PIA states. In addition, the expression of SSTR2A in the dorsal horn of the spinal cord was significantly higher in DA than in DA.1U rats. All of the findings suggest a higher local analgesic effect of OCT in DA rats than DA.1U rats, which might be associated with the MHC genes.

[Postoperative analgesia effect of different background volumes of ropivacaine in continuous tibial nerve block in patients with calcaneal surgery].

OBJECTIVE: To observe the clinical effect of different background volumes of ropivacaine in continuous tibial nerve block of postoperative analgesia after calcaneal surgery. METHODS: This study was a prospective, randomized, controlled study. Sixty cases of calcaneal visual analogue scale (ASA) I or II undergoing elective surgery were selected and randomly assigned to two groups, thirty cases in each group. The patients received popliteal fossa posterior tibial nerve block using ultrasound guided. The continuous stimulation catheter was inserted after successful position and the 0.2% ropivacaine was injected. The background volumes of the A and B groups were 5 mL/h and 3.2 mL/h. The VAS score, the sensory block and motor block of tibial nerve and common peroneal nerve, and the satisfaction of the patients at h 12, h 24 and h 48 were recorded after catheter insertion. RESULTS: The VAS scores at the three time points (h 12, h 24 and h 48) on the two groups of the patients were compared, and the difference was not statistically significant (P > 0.05). The difference of the sensory block and the motor block of the tibial nerve at the three time points (h 12, h 24 and h 48) on the two groups of the patients were also compared, and the difference was not statistically significant (P> 0.05). The difference of the sensory block and the motor block of common peroneal nerve at h 48 hs was statistically significant, group A was higher than the group B (P< 0.05). The difference of the patient satisfaction at the three time points (h 12, h 24 and h 48) on the two groups was not statistically significant (P> 0.05). CONCLUSION: The use of 0.2% ropivacaine with the background volume of 3.2 mL/h in continuous tibial nerve block can provide good analgesia and reduce the incidence of the sensory block and motor block of the common peroneal nerve.

Paclitaxel inhibits mRNA transport in axons.

Paclitaxel is an integral component of solid tumor treatment. This chemotherapeutic agent provokes an often irreversible peripheral sensory neuropathy with pathological features of distal axonal degeneration. Current pathological concepts assume that polymerization of axonal microtubules and mitochondrial dysfunction contributes to the development of paclitaxel-induced peripheral neuropathy. The relationship, however, between microtubule stabilization, mitotoxicity and axonal degeneration is still not completely understood. To explore the function of axonal mitochondria we treated transgenic mice that harbor cyan fluorescent protein (CFP)-labeled neuronal mitochondria with repeated doses of paclitaxel and assessed neuropathic changes by nerve conduction and histological studies. In addition, mitochondrial content and morphology was determined by ex vivo imaging of axons containing CFP-labeled mitochondria. Using quantitative RT-PCR and fluorescence-labeled mRNA we determined axonal mRNA transport of nuclear encoded mitochondrial proteins. Prolonged treatment with high doses of paclitaxel-induced a predominant sensory neuropathy in mice. Although mitochondrial velocity in axons per se was not altered, we observed significant changes in mitochondrial morphology, suggesting that paclitaxel treatment impairs the dynamics of axonal mitochondria. These changes were caused by decreased levels of nuclear encoded mRNA, including the mitochondrial fusion/fission machinery. Moreover, impaired axonal mRNA transport in vitro resulted in mitochondrial dysfunction and subsequent axonal degeneration. Taken together, our experiments provide evidence that disrupted axonal transport of nuclear derived mRNA plays a crucial role in the pathogenesis of paclitaxel-induced sensory neuropathy.

Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats.

This study examined the role of ß-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in α-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly (P < 0.05) increased bladder capacity from 58.0 ± 4.7% to 85.8 ± 10.3% and 96.5 ± 10.7%, respectively, of saline control capacity, while TNS failed to inhibit spinal reflex bladder contractions. After administering propranolol (3 mg/kg iv, a ß1/ß2-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly (P < 0.05) reduced to 64.5 ± 9.5% and 64.7 ± 7.3%, respectively, of the saline control capacity. However, the residual PNS inhibition (about 10% increase in capacity) was still statistically significant (P < 0.05). Propranolol treatment also significantly (P = 0.0019) increased the amplitude of bladder contractions but did not change the control bladder capacity. Naloxone (1 mg/kg iv, an opioid receptor antagonist) had no effect on either spinal reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly (P < 0.05) reduced the amplitude of the reflex bladder contractions. This study indicates an important role of ß1/ß2-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity.

Temporal profile of the effects of regional anesthesia on the cutaneous reflexes of foot muscles.

We analyzed the effects of an anesthetic sciatic nerve block on the cutaneomuscular reflex (cMR) and the cutaneous silent period (cSP) of foot muscles, in order to investigate further the type of fibers involved in their generation. In 14 neurologically normal patients with indication for surgical treatment of hallux valgus, we recorded from the extensor digitorum brevis muscle the reflex responses elicited by high-intensity electrical stimulation of the big toe at various time periods, ranging from 0 to 20 min, after ultrasound-guided sciatic nerve popliteal anesthetic block. The first effect was a delay in cSP onset latency, with no changes in end latency. The cMR remained unaltered up to when subjects were no longer able to maintain the contraction. The effects of local anesthetics on peripheral nerves allow for recognition of the different types of fibers contributing to the cMR and the cSP in muscles of the lower limb.

Beyond muscular effects: depression of spinal recurrent inhibition after botulinum neurotoxin A.

The natural target of the botulinum neurototoxin type A (BoNT-A) is the neuromuscular junction. When injected into a muscle, BoNT-A is internalized by motoneurone terminals where it functions as an endopeptidase, cleaving protein components of the synaptic machinery responsible for vesicle docking and exocytosis. As a result, BoNT-A induces a characteristic flaccid paralysis of the affected muscle. In animal models, BoNT-A applied in the periphery can also influence central activity via retrograde transport and transcytosis. An analogous direct central effect in humans is still debated. The present study was designed to address whether BoNT-A modifies the activity of the spinal recurrent inhibitory pathways, when injected at muscular level, in humans. To avoid methodological bias, the recurrent inhibition from an injected muscle (soleus) was investigated on an untreated muscle (quadriceps), and stimulation parameters (producing recurrent inhibition) were monitored on a third non-injected muscle but innervated by the same nerve as the soleus (flexor digitorum brevis). The experiments were performed on 14 post-stroke patients exhibiting spasticity in ankle plantarflexors, candidates for BoNT-A. One month after BoNT-A, the level of recurrent inhibition was depressed. It is suggested that the depression of recurrent inhibition was induced by BoNT-A, injected peripherally, through axonal transport and blockade of the cholinergic synapse between motoneurone recurrent collaterals and Renshaw cells.

Transsynaptic inhibition of spinal transmission by A2 botulinum toxin.

Type A botulinum toxin blocks not only ACh release from motor nerve terminals but also central synaptic transmission, including glutamate, noradrenaline, dopamine, ATP, GABA and glycine. Neurotoxins (NTXs) are transported by both antero- and retrogradely along either motor or sensory axons for bidirectional delivery between peripheral tissues or the CNS. A newly developed type A2 NTX (A2NTX) injected into one rat foreleg muscle was transported to the contralateral muscle. This finding was consistent with the NTX traveling retrogradely via spinal neurons and then transsynaptically through motor neurons to the contralateral motor neurons within the spinal cord and on to the soleus muscle. In the present study we found that toxin injection into the rat left soleus muscle clearly induced bilateral muscle relaxation in a dose-dependent fashion, although the contralateral muscle relaxation followed the complete inhibition of toxin-injected ipsilateral muscles. The toxin-injected ipsilateral muscle relaxation was faster and stronger in A2NTX-treated rats than A1LL (BOTOX). A1LL was transported almost equally to the contralateral muscle via neural pathways and the bloodstream. In contrast, A2NTX was mainly transported to contralateral muscles via the blood. A1LL was more successfully transported to contralateral spinal neurons than A2NTX. We also demonstrated that A1LL and A2NTX were carried from peripheral to CNS and vice versa by dual antero- and retrograde axonal transport through either motor or sensory neurons.

Peptide mimetic of the S100A4 protein modulates peripheral nerve regeneration and attenuates the progression of neuropathy in myelin protein P0 null mice.

We recently found that S100A4, a member of the multifunctional S100 protein family, protects neurons in the injured brain and identified two sequence motifs in S100A4 mediating its neurotrophic effect. Synthetic peptides encompassing these motifs stimulated neuritogenesis and survival in vitro and mimicked the S100A4-induced neuroprotection in brain trauma. Here, we investigated a possible function of S100A4 and its mimetics in the pathologies of the peripheral nervous system (PNS). We found that S100A4 was expressed in the injured PNS and that its peptide mimetic (H3) affected the regeneration and survival of myelinated axons. H3 accelerated electrophysiological, behavioral and morphological recovery after sciatic nerve crush while transiently delaying regeneration after sciatic nerve transection and repair. On the basis of the finding that both S100A4 and H3 increased neurite branching in vitro, these effects were attributed to the modulatory effect of H3 on initial axonal sprouting. In contrast to the modest effect of H3 on the time course of regeneration, H3 had a long-term neuroprotective effect in the myelin protein P0 null mice, a model of dysmyelinating neuropathy (Charcot-Marie-Tooth type 1 disease), where the peptide attenuated the deterioration of nerve conduction, demyelination and axonal loss. From these results, S100A4 mimetics emerge as a possible means to enhance axonal sprouting and survival, especially in the context of demyelinating neuropathies with secondary axonal loss, such as Charcot-Marie-Tooth type 1 disease. Moreover, our data suggest that S100A4 is a neuroprotectant in PNS and that other S100 proteins, sharing high homology in the H3 motif, may have important functions in PNS pathologies.

Sonographic visualization of the first branch of the lateral plantar nerve (baxter nerve): technique and validation using perineural injections in a cadaveric model.

OBJECTIVES: The primary purpose of this investigation was to document the ability of high-resolution sonography to accurately identify the first branch of the lateral plantar nerve (FBLPN) using sonographically guided perineural injections in an unembalmed cadaveric model. METHODS: single experienced operator completed sonographically guided perineural FBLPN injections in 12 unembalmed cadaveric specimens (6 right and 6 left) obtained from 10 donors (5 male and 5 female) aged 47 to 95 years (mean, 71 years) with an average body mass index of 24.2 kg/m(2) (range, 17.2-31.6 kg/m(2)). All injections were completed using 22-gauge, 38-mm stainless steel needles to deliver 1 mL of 50% diluted colored latex adjacent to the FBLPN in the abductor hallucis-quadratus plantae (AH-QP) interval. Six injections were completed using a cart-based ultrasound (US) machine and a 17-5-MHz transducer, and 6 were completed using a portable US machine and a 12-3-MHz transducer. Nerve conspicuity was graded on a 4-point scale (1, poor; 4, excellent). After a minimum of 24 hours, study coinvestigators dissected each specimen to assess injectate placement. RESULTS: All 12 injections accurately placed latex onto the FBLPN within the AH-QP interval, with 11 of 12 (91%) resulting in complete nerve coverage. Proximal latex overflow to the lateral plantar nerve occurred in 82% of cases (10 of 12). The average distance between the plantar fascia and injected latex was 1.2 cm (range, 1.0-1.75 cm). No vascular injury was seen in any specimen. The average nerve conspicuities were 3.7 (range, 3-4) using the cart-based US machine and 1.8 (range, 1-4) using the portable US machine. CONCLUSIONS: Sonographic visualization of the FBLPN in the AH-QP interval is feasible and should be considered for diagnostic and therapeutic purposes in patients presenting with chronic or atypical heel pain syndromes. Further clinical experience should refine the role of FBLPN sonography and explore the utility of sonographically guided diagnostic and therapeutic FBLPN perineural injections.

Autocrine motility factor injection for motor plate regeneration and muscle function restoration--a pilot study.

BACKGROUND: Autocrine motility factor (AMF) is a multifunctional cytokine that promotes cellular adhesion, proliferation, motility, anti-apoptosis, and tissue repair. Direct nerve implantation (DNI) is considered to be effective in peripheral motor nerve injuries with disuse of the distal nerve; however, the repaired muscle function is not satisfactory. In our study, purified AMF was injected in reinnervated muscle after DNI with the intention of assessing if AMF, as a malignant tumor-related cytokine, could improve motor plate regeneration and neuromuscular function restoration. METHODS: Purified AMF, which was extracted from AMF-transfected myoblast-conditioned medium, was regularly injected into the rat gastrocnemius in an established rat gastrocnemius denervation and reinnervation model. The nerve conduction velocity (NCV) of the tibial nerve, peak-to-peak value (PPV), area under the curve (AUC) of the compound muscle action potential (CMAP) and the Tibial Functional Index (TFI) were measured at 8, 16 and 24 weeks after injection. The regenerated endplates in gastrocnemius were examined by histochemical staining. In another group, an AMF-free solution was injected as the control. RESULTS: After the AMF injection, the direct-nerve-implanted muscle function recovery was better in terms of both the nerve velocity and the quality. The endplates in the experimental group also had a quantitative advantage in restoration. After comparing the histochemical-stained tissues, no indications of tumorigenesis were detected. CONCLUSIONS: AMF had positive effects on neuromuscular reparation and need more detailed research to determine the signalling pathways and side effects of AMF.

Attenuating effect of standardized fruit extract of Punica granatum L in rat model of tibial and sural nerve transection induced neuropathic pain.

BACKGROUND: Injury to a nerve is the most common reason of acquired peripheral neuropathy. Therefore, searching for effective substance to recover of nerve after injury is need of present era. The current study investigates the protective potential of Standardized Fruit Extract of Punica granatum L (PFE) [Ellagic acid (41.6%), Punicalagins (10%), Granatin (5.1%)] in Tibial & Sural Nerve Transection (TST) induced neuropathic pain in rats. METHODS: TST was performed by sectioning tibial and sural nerve portions of the sciatic nerve and leaving the common peroneal nerve intact. Acetone drop, pin-prick, hot plate, paint brush & Walking Track tests were performed to assess cold allodynia; mechanical heat, hyperalgesia and dynamic mechanical allodynia & tibial functional index respectively. The levels of TNF-α, TBARS, GSH and Nitrite were measured in the sciatic nerve as an index of inflammation & oxidative stress. RESULTS: TST led to significant development of cold allodynia; mechanical and heat hyperalgesia; dynamic mechanical allodynia; functional deficit in walking along with rise in the levels of TBARS, TNF-α, GSH and Nitrite. Administrations of PFE (100 & 300 mg/kg oral), significantly attenuate TST induced behavioral & biochemical changes. Pretreatments of BADGE (120 mg/kg IP) a PPAR-γ antagonist and nitric oxide precursor L-arginine (100 mg/kg IP) abolished the protective effect of PFE. Whereas, pretreatment of L-NAME (5 mg/kg IP) a NOS inhibitor significantly potentiated PFE's protective effect of PFE. CONCLUSION: PFE shown to have attenuating effect in TST induced neuropathic pain which may be attributed to potential PPAR-gamma agonistic activity, nitric oxide inhibitory, anti-inflammatory and anti oxidative actions.

Differential modulation of crossed and uncrossed reflex pathways by clonidine in adult cats following complete spinal cord injury.

Clonidine, an α-noradrenergic agonist, facilitates hindlimb locomotor recovery after complete spinal transection (i.e. spinalization) in adult cats. However, the mechanisms involved in clonidine-induced functional recovery are poorly understood. Sensory feedback from the legs is critical for hindlimb locomotor recovery in spinalized mammals and clonidine could alter how spinal neurons respond to peripheral inputs in adult spinalized cats. To test this hypothesis we evaluated the effect of clonidine on the responses of hindlimb muscles, primarily in the left hindlimb, evoked by stretching the left triceps surae muscles and by stimulating the right tibial and superficial peroneal nerves in eight adult decerebrate cats that were spinalized 1 month before the terminal experiment. Cats were not trained following spinalization. Clonidine had no consistent effect on responses of ipsilateral muscles evoked by triceps surae muscle stretch. However, clonidine consistently potentiated the amplitude and duration of crossed extensor responses. Moreover, following clonidine injection, stretch and tibial nerve stimulation triggered episodes of locomotor-like activity in approximately one-third of trials. Differential effects of clonidine on crossed reflexes and on ipsilateral responses to muscle stretch indicate an action at a pre-motoneuronal site. We conclude that clonidine facilitates hindlimb locomotor recovery following spinalization in untrained cats by enhancing the excitability of central pattern generating spinal neurons that also participate in crossed extensor reflex transmission.

Differential role of opioid receptors in tibial nerve inhibition of nociceptive and nonnociceptive bladder reflexes in cats.

Naloxone (an opioid receptor antagonist) was used to examine the role of opioid mechanisms in bladder reflexes and in somatic afferent inhibition of these reflexes by tibial nerve stimulation (TNS). Experiments were conducted in α-chloralose-anesthetized cats when the bladder was infused with saline or 0.25% acetic acid (AA). The bladder volume was measured at the first large-amplitude (>30 cmH(2)O) contraction during a cystometrogram and termed "estimated bladder capacity" (EBC). AA irritated the bladder, induced bladder overactivity, and significantly (P < 0.0001) reduced EBC to 14.3 ± 1.9% of the saline control. TNS (5 Hz, 0.2 ms) at 4 and 8 times the threshold (T) intensity for inducing an observable toe movement suppressed AA-induced bladder overactivity and significantly increased EBC to 41.5 ± 9.9% (4T, P < 0.05) and 46.1 ± 7.9% (8T, P < 0.01) of the saline control. Naloxone (1 mg/kg iv) completely eliminated TNS inhibition of bladder overactivity. Naloxone (0.001-1 mg/kg iv) did not change EBC during AA irritation. However, during saline infusion naloxone (1 mg/kg iv) significantly (P < 0.01) reduced EBC to 66.5 ± 8.1% of the control EBC. During saline infusion, TNS induced an acute increase in EBC and an increase that persisted following the stimulation. Naloxone (1 mg/kg) did not alter either type of inhibition. However, naloxone administered during the poststimulation inhibition decreased EBC. These results indicate that opioid receptors have different roles in modulation of nociceptive and nonnociceptive bladder reflexes and in somatic afferent inhibition of these reflexes, raising the possibility that opioid receptors may be a target for pharmacological treatment of lower urinary tract disorders.

Inhibition of bladder overactivity by a combination of tibial neuromodulation and tramadol treatment in cats.

Our recent study in cats revealed that inhibition of bladder overactivity by tibial nerve stimulation (TNS) depends on the activation of opioid receptors. TNS is a minimally invasive treatment for overactive bladder (OAB), but its efficacy is low. Tramadol (an opioid receptor agonist) is effective in treating OAB but elicits significant adverse effects. This study was to determine if a low dose of tramadol (expected to produce fewer adverse effects) can enhance the TNS inhibition of bladder overactivity. Bladder overactivity was induced in α-chloralose-anesthetized cats by an intravesical infusion of 0.25% acetic acid (AA) during repeated cystometrograms (CMGs). TNS (5 Hz) at two to four times the threshold intensity for inducing toe movement was applied during CMGs before and after tramadol (0.3-7 mg/kg iv) to examine the interaction between the two treatments. AA irritation significantly reduced bladder capacity to 24.8 ± 3.3% of the capacity measured during saline infusion. TNS alone reversibly inhibited bladder overactivity and significantly increased bladder capacity to 50-60% of the saline control capacity. Tramadol administered alone in low doses (0.3-1 mg/kg) did not significantly change bladder capacity, whereas larger doses (3-7 mg/kg) increased bladder capacity (50-60%). TNS in combination with tramadol (3-7 mg/kg) completely reversed the effect of AA. Tramadol also unmasked a prolonged (>2 h) TNS inhibition of bladder overactivity that persisted after termination of the stimulation. The results suggest a novel treatment strategy for OAB by combining tibial neuromodulation with a low dose of tramadol, which is minimally invasive with a potentially high efficacy and fewer adverse effects.

Adult rat mesenchymal stem cells delay denervated muscle atrophy.

To evaluate the function of rat mesenchymal stem cells (rMSCs) on denervated gastrocnemius muscles and to address the role of ciliary neurotrophic factor (CNTF) in rMSCs, denervated Wistar rats were separately injected with culture media (sham control), CNTF protein, 2.5 × 10(5) siCNTF-treated rMSCs, 2.5 × 10(5) GFP-transfected rMSCs, or 2.5 × 10(5) untreated rMSCs. Muscle function was assessed at different time points post-surgery. Tibial nerve and gastrocnemius muscle samples were taken at 4, 8, and 12 weeks for histochemistry, and neuromuscular junction repair was also examined by electron microscopy. Fluorescence immunocytochemistry on tissue sections confirmed neurotrophin expression in rMSCs but with little evidence of neuronal differentiation. The engraftment of rMSCs significantly preserved the function of denervated gastrocnemius muscle based both on evaluation of muscle function and direct examination of muscle tissue. Further, the density and depth of the junctional folds were visibly reduced 12 weeks after surgery and transplantation, especially in control group. Knockdown of CNTF expression in rMSCs failed to block muscle preservation, although administration of CNTF protein alone inhibited muscle atrophy, which indicating that delivery of rMSCs could preserve gastrocnemius muscle function following denervation and post-junctional mechanisms involved in the repairing capability of rMSCs.