Transdermal delivery of 4-aminopyridine accelerates motor functional recovery and improves nerve morphology following sciatic nerve crush injury in mice

Oral 4-aminopyridine(4-AP)is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral nerve injury including the promotion of re-myelination,improvement of nerve conductivity,and acceleration of functional recovery.We hypothesized that,instead of oral or injection administration,transdermal 4-AP(TD-4-AP)could also improve functional recovery after traumatic peripheral nerve injury.Mice with surgical traumatic peripheral nerve injury received TD-4AP or vehicle alone and were examined for skin permeability,pharmacokinetics,functional,electrophysiological,and nerve morphological properties.4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to TD-4-AP dose.While a single dose of TD-4-AP administration demonstrated rapid transient improvement in motor function,chronic TD-4-AP treatment significantly improved motor function and nerve conduction and these effects were associated with fewer degenerating axons and thicker myelin sheaths than those from vehicle controls.These findings provide direct evidence for the potential transdermal applicability of 4-AP and demonstrate that 4-AP delivered through the skin can enhance in-vivo functional recovery and nerve conduction while decreasing axonal degeneration.The animal experiments were approved by the University Committee on Animal Research(UCAR)at the University of Rochester(UCAR-2009-019)on March 31,2017.     

Intraoperative single administration of neutrophil peptide 1 accelerates the early functional recovery of peripheral nerves after crush injury

Neutrophil peptide 1 belongs to a family of peptides involved in innate immunity. Continuous intramuscular injection of neutrophil peptide 1 can promote the regeneration of peripheral nerves, but clinical application in this manner is not convenient. To this end, the effects of a single intraoperative administration of neutrophil peptide 1 on peripheral nerve regeneration were experimentally observed. A rat model of sciatic nerve crush injury was established using the clamp method. After model establishment, a normal saline group and a neutrophil peptide 1 group were injected with a single dose of normal saline or 10 μg/mL neutrophil peptide 1, respectively. A sham group, without sciatic nerve crush was also prepared as a control. Sciatic nerve function tests, neuroelectrophysiological tests, and hematoxylin-eosin staining showed that the nerve conduction velocity, sciatic functional index, and tibialis anterior muscle fiber cross-sectional area were better in the neutrophil peptide 1 group than in the normal saline group at 4 weeks after surgery. At 4 and 8 weeks after surgery, there were no differences in the wet weight of the tibialis anterior muscle between the neutrophil peptide 1 and saline groups. Histological staining of the sciatic nerve showed no significant differences in the number of myelinated nerve fibers or the axon cross-sectional area between the neutrophil peptide 1 and normal saline groups. The above data confirmed that a single dose of neutrophil peptide 1 during surgery can promote the recovery of neurological function 4 weeks after sciatic nerve injury. All the experiments were approved by the Medical Ethics Committee of Peking University People's Hospital, China(approval No. 2015-50) on December 9, 2015.     

ISP and PAP4 peptides promote motor functional recovery after peripheral nerve injury

Both intracellular sigma peptide(ISP) and phosphatase and tensin homolog agonist protein(PAP4) promote nerve regeneration and motor functional recovery after spinal cord injury. However, the role of these two small peptides in peripheral nerve injury remains unclear. A rat model of brachial plexus injury was established by crush of the C6 ventral root. The rats were then treated with subcutaneous injection of PAP4(497 μg/d, twice per day) or ISP(11 μg/d, once per day) near the injury site for 21 successive days. After ISP and PAP treatment, the survival of motoneurons was increased, the number of regenerated axons and neuromuscular junctions was increased, muscle atrophy was reduced, the electrical response of the motor units was enhanced and the motor function of the injured upper limbs was greatly improved in rats with brachial plexus injury. These findings suggest that ISP and PAP4 promote the recovery of motor function after peripheral nerve injury in rats. The animal care and experimental procedures were approved by the Laboratory Animal Ethics Committee of Jinan University of China(approval No. 20111008001) in 2011.     

Electrical stimulation impairs early functional recovery and accentuates skeletal muscle atrophy after sciatic nerve crush injury in rats

Neuromuscular recovery after peripheral nerve lesion depends on the regeneration of severed axons that re‐establish their functional connection with the denervated muscle. The aim of this study was to determine the effects of electrical stimulation (ES) on the neuromuscular recovery after nerve crush injury in rats. Electrical stimulation was carried out on the tibialis anterior (TA) muscle after sciatic nerve crush injury in a rat model. Six ES sessions were administered every other day starting from day 3 postinjury until the end of the experiment (day 14). The sciatic functional index was calculated. Muscle excitability, neural cell adhesion molecule (N‐CAM) expression, and muscle fiber cross‐sectional area (CSA) were accessed from TA muscle. Regenerated sciatic nerves were analyzed by light and confocal microscopy. Both treated (crush+ES) and untreated (crush) groups had their muscle weight and CSA decreased compared with the normal group (P < 0.05). Electrical stimulation accentuated muscle fiber atrophy more in the crush+ES than in the crush group (P < 0.05). N‐CAM expression increased in both crush and crush+ES groups compared with the normal group (P < 0.05). Regenerated nerves revealed no difference between the crush and crush+ES groups. Nevertheless, functional recovery at day 14 post‐injury was significantly lower in crush+ES group compared with the crush group. In addition, the crush+ES group had chronaxie values significantly higher on days 7 and 13 compared with the crush group, which indicates a decrease in muscle excitability in the crush+ES animals. The results of this study do not support a benefit of the tested protocol of ES during the period of motor nerve recovery following injury. Muscle Nerve, 2010     

Combination therapy using evening primrose oil and electrical stimulation to improve nerve function following a crush injury of sciatic nerve in male rats

Peripheral nerve injuries with a poor prognosis are common. Evening primrose oil (EPO) has beneficial biological effects and immunomodulatory properties. Since electrical activity plays a major role in neural regeneration, the present study investigated the effects of electrical stimulation (ES), combined with evening primrose oil (EPO), on sciatic nerve function after a crush injury in rats. In anesthetized rats, the sciatic nerve was crushed using small haemostatic forceps followed by ES and/or EPO treatment for 4 weeks. Functional recovery of the sciatic nerve was assessed using the sciatic functional index. Histopathological changes of gas-trocnemius muscle atrophy were investigated by light microscopy. Electrophysiological changes were assessed by the nerve conduction velocity of sciatic nerves. Immunohistochemistry was used to determine the remy-elination of the sciatic nerve following the interventions. EPO + ES, EPO, and ES obviously improved sciatic nerve function assessed by the sciatic functional index and nerve conduction velocity of the sciatic nerve at 28 days after operation. Expression of the peripheral nerve remyelination marker, protein zero (P0), was in-creased in the treatment groups at 28 days after operation. Muscle atrophy severity was decreased significantly while the nerve conduction velocity was increased significantly in rats with sciatic nerve injury in the injury+ EPO + ES group than in the EPO or ES group. Totally speaking, the combined use of EPO and ES may pro-duce an improving effect on the function of sciatic nerves injured by a crush. The increased expression of P0 may have contributed to improving the functional effects of combination therapy with EPO and ES as well as the electrophysiological and histopathological features of the injured peripheral nerve.     

Reinnervation of the tibialis anterior following sciatic nerve crush injury: a confocal microscopic study in transgenic mice

Transgenic mice whose axons and Schwann cells express fluorescent chromophores enable new imaging techniques and augment concepts in developmental neurobiology. The utility of these tools in the study of traumatic nerve injury depends on employing nerve models that are amenable to microsurgical manipulation and gauging functional recovery. Motor recovery from sciatic nerve crush injury is studied here by evaluating motor endplates of the tibialis anterior muscle, which is innervated by the deep peroneal branch of the sciatic nerve. Following sciatic nerve crush, the deep surface of the tibialis anterior muscle is examined using whole mount confocal microscopy, and reinnervation is characterized by imaging fluorescent axons or Schwann cells (SCs). One week following sciatic crush injury, 100% of motor endplates are denervated with partial reinnervation at 2 weeks, hyperinnervation at 3 and 4 weeks, and restoration of a 1:1 axon to motor endplate relationship 6 weeks after injury. Walking track analysis reveals progressive recovery of sciatic nerve function by 6 weeks. SCs reveal reduced S100 expression within 2 weeks of denervation, correlating with regression to a more immature phenotype. Reinnervation of SCs restores S100 expression and a fully differentiated phenotype. Following denervation, there is altered morphology of circumscribed terminal Schwann cells demonstrating extensive process formation between adjacent motor endplates. The thin, uniformly innervated tibialis anterior muscle is well suited for studying motor reinnervation following sciatic nerve injury. Confocal microscopy may be performed coincident with other techniques of assessing nerve regeneration and functional recovery.     

Effect of locomotor training on muscle performance in the context of nerve-muscle communication dysfunction

Introduction: The effects of locomotor training (LT) on skeletal muscle after peripheral nerve injury and acetylcholinesterase deficiency are not well documented. Methods: We determined the effects of LT on mouse soleus muscle performance after sciatic nerve transection with excision (full and permanent denervation), nerve transection (partial functional reinnervation), nerve crush (full denervation with full functional reinnervation), and acetylcholinesterase deficiency (alteration in neuromuscular junction functioning). Results: We found no significant effect of LT on the recovery of soleus muscle weight, maximal force in response to muscle stimulation, and fatigue resistance after nerve transection with or without excision. However, LT significantly increased soleus muscle fatigue resistance after nerve crush and acetylcholinesterase deficiency. Moreover, hindlimb immobilization significantly aggravated the deficit in soleus muscle maximal force production and atrophy after nerve crush. Conclusions: LT is beneficial, and reduced muscle use is detrimental for intrinsic muscle performance in the context of disturbed nerve–muscle communication. Muscle Nerve, 2012     

钙通道阻滞剂对大鼠坐骨神经损伤后c-fos表达及神经功能的影响

目的探讨钙通道阻滞剂(CCB)对周围神经损伤后c-fos表达及神经功能的影响。方法制作坐骨神经嵌压性损伤大鼠模型,给予模型大鼠分别腹腔注射氟桂利嗪1mg/kg(低剂量组)、2mg/kg(高剂量组),或生理盐水10ml/kg(模型组)。在坐骨神经嵌压后第1周、第4周时取大鼠坐骨神经,采用免疫组织化学、行为医学和电生理学的方法测定c-fos阳性细胞数及第4周时足趾间距、神经传导速度(NCV);并与正常大鼠比较。结果(1)损伤后1周时,模型组、氟桂利嗪低剂量组坐骨神经c-fos阳性细胞数显著多于正常对照组(均P<0.01);氟桂利嗪高剂量组c-fos阳性细胞数轻度增加,也显著多于正常对照组(P<0.05),但明显少于模型组和氟桂利嗪低剂量组(均P<0.01);损伤4周时各组c-fos阳性细胞数均无明显增高。(2)损伤后4周时,模型组和氟桂利嗪低剂量组、高剂量组坐骨神经NCV显著慢于正常对照组(均P<0.01),氟桂利嗪低剂量组、高剂量组的NCV快于模型组(P<0.05,P<0.01)。(3)损伤后4周时,模型组大鼠右后肢足趾间距明显小于其他3组(均P<0.01);氟桂利嗪高剂量组、低剂量组与正常对照组比较差异无统计学意义(均P>0.05)。结论CCB使周围神经损伤后早期c-fos表达下调,并使神经功能受损减轻。     

Craniocerebral injury promotes the repair of peripheral nerve injury

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

Miconazole enhances nerve regeneration and functional recovery after sciatic nerve crush injury

Introduction: Improving axonal outgrowth and remyelination is crucial for peripheral nerve regeneration. Miconazole appears to enhance remyelination in the central nervous system. In this study we assess the effect of miconazole on axonal regeneration using a sciatic nerve crush injury model in rats. Methods: Fifty Sprague‐Dawley rats were divided into control and miconazole groups. Nerve regeneration and myelination were determined using histological and electrophysiological assessment. Evaluation of sensory and motor recovery was performed using the pinprick assay and sciatic functional index. The Cell Counting Kit‐8 assay and Western blotting were used to assess the proliferation and neurotrophic expression of RSC 96 Schwann cells. Results: Miconazole promoted axonal regrowth, increased myelinated nerve fibers, improved sensory recovery and walking behavior, enhanced stimulated amplitude and nerve conduction velocity, and elevated proliferation and neurotrophic expression of RSC 96 Schwann cells. Discussion: Miconazole was beneficial for nerve regeneration and functional recovery after peripheral nerve injury. Muscle Nerve 57 : 821–828, 2018     

The protective effects of Achyranthes bidentata polypeptides in an experimental model of mouse sciatic nerve crush injury

We have separated the active polypeptides from aqueous extracts of Achyranthes bidentata Blume (ABPP), a commonly prescribed Chinese medicinal plant with a range of pharmaceutical properties. We investigated the effects of ABPP administration on peripheral nerve regeneration in a mouse sciatic nerve crush injury model. After nerve crush, the mice received daily tail vein injections of 1, 4, and 16 mg/kg of ABPP, 65 μg/kg of methylcobalamin, and vehicle saline, respectively, over a 21-day period. At 1, 3, 6, 9, 12, 15, 18 and 21 days after nerve crush, the animals were subjected to walking track analysis for evaluating the sciatic functional index (SFI) values. At day 21 the animals were anesthetized, and the compound muscle action potential and nerve conduction velocity were respectively recorded. After the animals were killed, the sciatic nerve was examined with immunohistochemistry and electron microscopy, and gastrocnemius muscle was analyzed with Masson trichome staining. The results indicated that treatment with ABPP at a dose range (1-16 mg/kg) promoted histological regeneration and functional recovery of the injured sciatic nerve and its target muscle, yielding a desired efficacy greater than that by vehicle treatment and close to that by methylcobalamin (65 μg/kg). These findings suggest that plant polypeptides, ABPP, may be a potential agent in ameliorating of neuropathy caused by sciatic nerve crush.     

Restorative effect and mechanism of mecobalamin on sciatic nerve crush injury in mice

Mecobalamin,a form of vitamin B12 containing a central metal element(cobalt),is one of the most important mediators of nervous system function.In the clinic,it is often used to accelerate recovery of peripheral nerves,but its molecular mechanism remains unclear.In the present study,we performed sciatic nerve crush injury in mice,followed by daily intraperitoneal administration of mecobalamin(65 μg/kg or 130 μg/kg) or saline(negative control).Walking track analysis,histomorphological examination,and quantitative real-time PCR showed that mecobalamin significantly improved functional recovery of the sciatic nerve,thickened the myelin sheath in myelinated nerve fibers,and increased the cross-sectional area of target muscle cells.Furthermore,mecobalamin upregulated m RNA expression of growth associated protein 43 in nerve tissue ipsilateral to the injury,and of neurotrophic factors(nerve growth factor,brain-derived nerve growth factor and ciliary neurotrophic factor) in the L4–6 dorsal root ganglia.Our findings indicate that the molecular mechanism underlying the therapeutic effect of mecobalamin after sciatic nerve injury involves the upregulation of multiple neurotrophic factor genes.     

Calcitonin pump improves nerve regeneration after transection injury and repair

Introduction: After nerve injury, excessive calcium impedes nerve regeneration. We previously showed that calcitonin improved nerve regeneration in crush injury. We aimed to validate the direct effect of calcitonin on transected and repaired nerve. Methods: Two rat groups (n = 8) underwent sciatic nerve transection followed by direct repair. In the calcitonin group, a calcitonin‐filled mini‐osmotic pump was implanted subcutaneously, with a catheter parallel to the repaired nerve. The control group underwent repair only, without a pump. Evaluation and comparison between the groups included: (1) compound muscle action potential recording of the extensor digitorum longus (EDL) muscle; (2) tetanic muscle force test of EDL; (3) nerve calcium concentration; and (4) nerve fiber count and calcified spot count. Results: The calcitonin pump group showed superior recovery. Conclusions: Calcitonin affects injured and repaired peripheral nerve directly. The calcitonin‐filled mini‐osmotic pump improved nerve functional recovery by accelerating calcium absorption from the repaired nerve. This finding has potential clinical applications. Muscle Nerve 51 : 229–234, 2015     

Determinants of nerve conduction recovery after nerve injuries: Compression duration and nerve fiber types

Introduction: The aims of this study were to determine the influences of: (1) timing of nerve decompression; and (2) nerve fiber types on the patterns of nerve conduction studies (NCS) after nerve injury. Methods: Nerve conduction studies (NCS) were performed on 3 models of nerve injury: (1) crush injury due to transient nerve compression (crush group); (2) chronic constriction injury (CCI), or permanent compression (CCI group); and (3) CCI with removal of ligatures, or delayed nerve decompression (De‐CCI group). Results: There were distinct patterns of NCS recovery. The crush and De‐CCI groups achieved similar motor nerve recovery, better than that of the CCI group. In contrast, recovery of sensory nerves was limited in the CCI and De‐CCI groups and was lower than in the crush group. Conclusions: Immediate relief of compression resulted in the best recovery of motor and sensory nerve conduction. In contrast, delayed decompression restored only motor nerve conduction. Muscle Nerve 52 : 107–112, 2015     

Electrical stimulation influences satellite cell differentiation after sciatic nerve crush injury in rats

Introduction: Electrical stimulation is often used to prevent muscle atrophy and preserve contractile function, but its effects on the satellite cell population after nerve injury are not well understood. In this study we aimed to determine whether satellite cell differentiation is affected by electrical stimulation after nerve crush. Methods: The sciatic nerves of Sprague‐Dawley (SD) rats were crushed. Half of the injured rats received daily electrical stimulation of the gastrocnemius muscle, and the others did not. Tests for detecting paired box protein 7 (Pax7), myogenic differentiation antigen (MyoD), embryonic myosin heavy chain (eMyHC), and force production were performed 2, 4, and 6 weeks after injury. Results: More Pax7⁺/MyoD⁺ nuclei in stimulated muscles were observed than in non‐stimulated muscles. eMyHC expression was elevated in stimulated muscles and correlated positively with enhanced force production. Conclusions: Increased satellite cell differentiation is correlated with preserved muscle function in response to electrical stimulation after nerve injury. Muscle Nerve 51: 400–411, 2015     

Macrophage-Derived Vascular Endothelial Growth Factor-A Is Integral to Neuromuscular Junction Reinnervation after Nerve Injury

Functional recovery in the end target muscle is a determinant of outcome after peripheral nerve injury. The neuromuscular junction (NMJ) provides the interface between nerve and muscle and includes non-myelinating terminal Schwann cells (tSCs). After nerve injury, tSCs extend cytoplasmic processes between NMJs to guide axon growth and NMJ reinnervation. The mechanisms related to NMJ reinnervation are not known. We used multiple mouse models to investigate the mechanisms of NMJ reinnervation in both sexes, specifically whether macrophage-derived vascular endothelial growth factor-A (Vegf-A) is crucial to establishing NMJ reinnervation at the end target muscle. Both macrophage number and Vegf-A expression increased in end target muscles after nerve injury and repair. In mice with impaired recruitment of macrophages and monocytes (Ccr2−/− mice), the absence of CD68+ cells (macrophages) in the muscle resulted in diminished muscle function. Using a Vegf-receptor 2 (VegfR2) inhibitor (cabozantinib; CBZ) via oral gavage in wild-type (WT) mice resulted in reduced tSC cytoplasmic process extension and decreased NMJ reinnervation compared with saline controls. Mice with Vegf-A conditionally knocked out in macrophages (Vegf-A^fl/fl; LysM^Cre mice) demonstrated a more prolonged detrimental effect on NMJ reinnervation and worse functional muscle recovery. Together, these results show that contributions of the immune system are integral for NMJ reinnervation and functional muscle recovery after nerve injury.SIGNIFICANCE STATEMENT This work demonstrates beneficial contributions of a macrophage-mediated response for neuromuscular junction (NMJ) reinnervation following nerve injury and repair. Macrophage recruitment occurred at the NMJ, distant from the nerve injury site, to support functional recovery at the muscle. We have shown hindered terminal Schwann cell (tSC) injury response and NMJ recovery with inhibition of: (1) macrophage recruitment after injury; (2) vascular endothelial growth factor receptor 2 (VegfR2) signaling; and (3) Vegf secretion from macrophages. We conclude that macrophage-derived Vegf is a key component of NMJ recovery after injury. Determining the mechanisms active at the end target muscle after motor nerve injury reveals new therapeutic targets that may translate to improve motor recovery following nerve injury.     

Overexpression of P2X4 receptor in Schwann cells promotes motor and sensory functional recovery and remyelination via BDNF secretion after nerve injury

Of the seven P2X receptor subtypes, P2X4 receptor (P2X4R) is widely distributed in the central nervous system, including in neurons, astrocytes, and microglia. Accumulating evidence supports roles for P2X4R in the central nervous system, including regulating cell excitability, synaptic transmission, and neuropathic pain. However, little information is available about the distribution and function of P2X4R in the peripheral nervous system. In this study, we find that P2X4R is mainly localized in the lysosomes of Schwann cells in the peripheral nervous system. In cultured Schwann cells, TNF-a not only enhances the synthesis of P2X4R protein but also promotes P2X4R trafficking to the surface of Schwann cells. TNF-a-induced BDNF secretion in Schwann cells is P2X4R dependent. in vivo experiments reveal that expression of P2X4R in Schwann cells of injured nerves is strikingly upregulated following nerve crush injury. Moreover, overexpression of P2X4R in Schwann cells by genetic manipulation promotes motor and sensory functional recovery and accelerates nerve remyelination via BDNF release following nerve injury. Our results suggest that enhancement of P2X4R expression in Schwann cells after nerve injury may be an effective approach to facilitate the regrowth and remyelination of injured nerves.     

Functional recovery following peripheral nerve injury in the transgenic Thy1‐GFP rat

Transgenic mice have been previously used to assess nerve regeneration following peripheral nerve injury. However, mouse models are limited by their small caliber nerves, short nerve lengths, and their inability to fully participate during behavioral assessments. The transgenic Thy1 GFP rat is a novel transgenic rat model designed to assess regeneration following peripheral nerve injury. However, return of functional and behavioral recovery following nerve injury has not yet been evaluated in these rats. In this study, we ask whether differences in anatomy, recovery of locomotion, myological, and histomorphological measures exist between transgenic Thy1 GFP rats when compared to wild type (WT) Sprague Dawley rats following unilateral sciatic nerve injury. We found that both motor and sensory neuronal architecture, overground and skilled locomotion, muscle force, motor unit number estimation (MUNE) and wet muscle weights, and histomorphometric assessments are similar between both genetic phenotypes. Overall, these data support the use of the transgenic Thy1‐GFP rat in experiments assessing functional and behavioral recovery following nerve injury and repair.     

蛇毒神经生长因子对神经损伤后脊髓前角运动神经元超微结构的保护作用

目的：研究周围神经损伤后神经生长因子对运动神经元的保护作用。方法：采用定位、定量、定时的方法钳夹大耳白免右坐骨神经,于损伤处注射蛇毒 ＮＧＦ ４００ Ｂｕ·ｋｇ－１·ｄ－１,神经损伤术后 １,３,７ｄ和 ２,３,４,６,８周动态观察脊髓腰段伤侧第 Ⅸ板层外侧群的大型运动神经元的超微结构变化,并对线粒体体密度变化进行定量分析。结果：神经损伤术后对照组超微结构的改变比实验组明显加重,实验组超微结构的恢复比对照组快。结论;ＮＧＦ对神经损伤后脊髓前角运动神经元超微结构的恢复有促进作用,从而对运动神经元可起一定的保护和促进恢复作用。     

Serial assessment of functional recovery following nerve injury using implantable thin‐film wireless nerve stimulators

Introduction: Comprehensive assessment of the time course of functional recovery following peripheral nerve repair is critical for surgical management of peripheral nerve injuries. This study describes the design and implementation of a novel implantable wireless nerve stimulator capable of repeatedly interfacing peripheral nerve tissue and providing serial evaluation of functional recovery postoperatively. Methods: Thin‐film wireless implants were fabricated and subcutaneously implanted into Lewis rats. Wireless implants were used to serially stimulate rat sciatic nerve and assess functional recovery over 3 months following various nerve injuries. Results: Wireless stimulators demonstrated consistent performances over 3 months in vivo and successfully facilitated serial assessment of nerve and muscle function following nerve crush and nerve transection injuries. Conclusions: This study highlights the ability of implantable wireless nerve stimulators to provide a unique view into the time course of functional recovery in multiple motor targets. Muscle Nerve 54 : 1114–1119, 2016