The neural mobilization technique modulates the expression of endogenous opioids in the periaqueductal gray and improves muscle strength and mobility in rats with neuropathic pain

Peripheral and central changes induced by neural mobilization in animal models of neuropathic pain: a systematic review

Introduction

Neural mobilization (NM) is a physiotherapy technique involving the passive mobilization of limb nerve structures with the aim to attempt to restore normal movement and structural properties. In recent years, human studies have shown pain relief in various neuropathic diseases and other pathologies as a result of this technique. Improvement in the range of motion (ROM), muscle strength and endurance, limb function, and postural control were considered beneficial effects of NM. To determine which systems generate these effects, it is necessary to conduct studies using animal models. The objective of this study was to gather information on the physiological effects of NM on the peripheral and central nervous systems (PNS and CNS) in animal models.

Methods

The search was performed in Medline, Pubmed and Web of Science and included 8 studies according to the inclusion criteria.

Results

The physiological effects found in the nervous system included the analgesic, particularly the endogenous opioid pathway, the inflammatory, by modulation of cytokines, and the immune system.

Conclusion

On the basis of these results, we can conclude that NM physiologically modifies the peripheral and central nervous systems in animal models.

Activation of HCN channels caused by elevated cAMP levels in periaqueductal gray promotes bone cancer pain

The periaqueductal gray (PAG) is an important relay center for the descending pathways that regulate nociceptive information transduction. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play critical roles in the nerve injury-induced pain hypersensitivity. Previous studies have identified that HCN1 and HCN2 channel protein located in the ventral-lateral periaqueductal gray (vlPAG), a region important for pain regulation. However, it is not clear whether the HCN channel in vlPAG is involved in bone cancer pain (BCP). In this study, we assessed the role of HCN channels in BCP by measuring changes of HCN channel expression and activity in vlPAG neurons in bone cancer rats. In the present study, the BCP model was established by injecting SHZ-88 breast cancer cells into the right tibia bone marrow in rats. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured to evaluate pain behavior in rats. HCN1 and HCN2 channels expression in vlPAG were detected by using Western Blot and immunohistochemistry. In addition, the cAMP level in vlPAG neurons was detected by ELISA, and HCN channel current (I_h) of vlPAG neurons was recorded by whole cell patch-clamp to evaluate HCN channel activity. As a result, decreased MWT and TWL were observed in rats on 7d after SHZ-88 cell inoculation, and the allodynia was sustained until 21d after inoculation. At the same time, HCN1 and HCN2 channels expression and neuronal I_h in vlPAG were significantly increased in BCP rats. In addition, the level of cAMP in vlPAG also increased after SHZ-88 cell inoculation. Furthermore, intravlPAG injection of ZD7288 (HCN channels antagonist) could significantly reduce hyperalgesia and the elevation of cAMP in vlPAG in BCP rats. Our observations suggest that the elevation of cAMP may promote the activation of HCN channels in vlPAG in bone cancer rats, thereby promoting the development of bone cancer pain.

Effects of Neural Mobilization on Sensory Dysfunction and Peripheral Nerve Degeneration in Rats With Painful Diabetic Neuropathy

OBJECTIVE

This study aims to evaluate the effectiveness of neural mobilization (NM) in the management of sensory dysfunction and nerve degeneration related to experimental painful diabetic neuropathy (PDN).

METHODS

This is a pre-clinical animal study performed in the streptozocin-induced diabetic rat model. Three groups were included: a treatment group of rats with PDN receiving NM under anesthesia (PDN-NM, n = 10), a sham treatment group of rats with PDN that received only anesthesia (PDN-Sham, n = 9), and a vehicle control group with nondiabetic animals (Vehicle, n = 10). Rats in the PDN-NM and PDN-Sham groups received 1 treatment session on days 10, 12, and 14 after streptozocin injection, with a 48-hour rest period between sessions. Behavioral tests were performed using von Frey and Plantar tests. Evaluation for peripheral nerve degeneration was performed through measuring protein gene product 9.5-positive intra-epidermal nerve fiber density in hind-paw skin biopsies. All measurements were performed by a blinded investigator.

RESULTS

The behavioral tests showed that a single NM session could reduce hyperalgesia, which was maintained for 48 hours. The second treatment session further improved this treatment effect, and the third session maintained it. These results suggest that it requires multiple treatment sessions to produce and maintain hypoalgesic effects. Skin biopsy analysis showed that the protein gene product 9.5-positive intra-epidermal nerve fiber density was higher on the experimental side of the PDN-NM group compared with the PDN-Sham group, suggesting NM may mitigate the degeneration of peripheral nerves.

CONCLUSION

This study demonstrated that NM may be an effective method to manage experimentally induced PDN, potentially through mitigation of nerve degeneration. Further studies are needed to develop standardized protocols for clinical use.

IMPACT

These findings provide neurophysiological evidence for the use of NM in PDN and can form the basis for the development of physical therapy-based programs in clinics.

Effects of Neural Mobilization on Pain Intensity, Disability, and Mechanosensitivity: An Umbrella Review With Meta-Meta-Analysis

OBJECTIVE

The purpose of this study was to assess the current evidence for the effects of neural mobilization (NM) treatments.

METHODS

Three umbrella reviews with meta-meta-analyses were conducted to determine the effects of NM on pain intensity and disability in people with musculoskeletal disorders and on mechanosensitivity in participants who were asymptomatic. The study used the grading criteria proposed by the Physical Activity Guidelines Advisory Committee to assess the quality of evidence.

RESULTS

One meta-meta-analysis revealed a statistically significant moderate effect on pain intensity (standardized mean difference [SMD] = -0.75, 95% CI = -1.12 to -0.38) but with evidence of heterogeneity (Q = 14.13; I2 = 65%). The study found a significantly large effect of NM on disability (SMD = -1.22, 95% CI = -2.19 to -0.26), again with evidence of heterogeneity (Q = 31.57; I2 = 87%). The third meta-meta-analysis showed a statistically significant moderate effect of NM on mechanosensitivity (SMD = 0.96, 95% CI = 0.35 to 1.57), with no evidence of heterogeneity (Q = 2.73; I2 = 63%). For all examined outcomes, the quality of evidence was limited.

CONCLUSION

Overall, the results indicated that although NM treatment had a moderate to large beneficial clinical effect on pain intensity and disability in people with musculoskeletal disorders and on mechanosensitivity in individuals who were asymptomatic, the quality of evidence was limited.

IMPACT

Neural mobilization treatments showed positive results on the pain intensity and disability in individuals with musculoskeletal conditions. Neural mobilization could be integrated into the physical therapy management, although more research is needed.

Neurodynamic Treatment Promotes Mechanical Pain Modulation in Sensory Neurons and Nerve Regeneration in Rats

Background: Somatic nerve injuries are a rising problem leading to disability associated with neuropathic pain commonly reported as mechanical allodynia (MA) and hyperalgesia. These symptoms are strongly dependent on specific processes in the dorsal root ganglia (DRG). Neurodynamic treatment (NDT), consisting of selective uniaxial nerve repeated tension protocols, effectively reduces pain and disability in neuropathic pain patients even though the biological mechanisms remain poorly characterized. We aimed to define, both in vivo and ex vivo, how NDT could promote nerve regeneration and modulate some processes in the DRG linked to MA and hyperalgesia. Methods: We examined in Wistar rats, after unilateral median and ulnar nerve crush, the therapeutic effects of NDT and the possible protective effects of NDT administered for 10 days before the injury. We adopted an ex vivo model of DRG organotypic explant subjected to NDT to explore the selective effects on DRG cells. Results: Behavioural tests, morphological and morphometrical analyses, and gene and protein expression analyses were performed, and these tests revealed that NDT promotes nerve regeneration processes, speeds up sensory motor recovery, and modulates mechanical pain by affecting, in the DRG, the expression of TACAN, a mechanosensitive receptor shared between humans and rats responsible for MA and hyperalgesia. The ex vivo experiments have shown that NDT increases neurite regrowth and confirmed the modulation of TACAN. Conclusions: The results obtained in this study on the biological and molecular mechanisms induced by NDT will allow the exploration, in future clinical trials, of its efficacy in different conditions of neuropathic pain.

Neurodynamics: is tension contentious?

Tensioning techniqueswere the first neurodynamic techniques used therapeutically in the management of people with neuropathies. This article aims to provide a balanced evidence-informed view on the effects of optimal tensile loading on peripheral nerves and the use of tensioning techniques. Whilst the early use of neurodynamics was centered within a mechanical paradigm, research into the working mechanisms of tensioning techniques revealed neuroimmune, neurophysiological, and neurochemical effects. In-vitro and ex-vivo research confirms that tensile loading is required for mechanical adaptation of healthy and healing neurons and nerves. Moreover, elimination of tensile load can have detrimental effects on the nervous system. Beneficial effects of tensile loading and tensioning techniques, contributing to restored homeostasis at the entrapment site, dorsal root ganglia and spinal cord, include neuronal cell differentiation, neurite outgrowth and orientation, increased endogenous opioid receptors, reduced fibrosis and intraneural scar formation, improved nerve regeneration and remyelination, increased muscle power and locomotion, less mechanical and thermal hyperalgesia and allodynia, and improved conditioned pain modulation. However, animal and cellular models also show that ‘excessive’ tensile forces have negative effects on the nervous system. Although robust and designed to withstand mechanical load, the nervous system is equally a delicate system. Mechanical loads that can be easily handled by a healthy nervous system, may be sufficient to aggravate clinical symptoms in patients. This paper aims to contribute to a more balanced view regarding the use of neurodynamics and more specifically tensioning techniques.

Effects of joint and nerve mobilisation on neuroimmune responses in animals and humans with neuromusculoskeletal conditions: a systematic review and meta-analysis

Supplemental Digital Content is Available in the Text.

There is evidence that joint and nerve mobilisations compared with sham or no intervention positively influence various neuroimmune responses in animal and human neuromusculoskeletal conditions.

Several animal and human studies revealed that joint and nerve mobilisations positively influence neuroimmune responses in neuromusculoskeletal conditions. However, no systematic review and meta-analysis has been performed. Therefore, this study aimed to synthesize the effects of joint and nerve mobilisation compared with sham or no intervention on neuroimmune responses in animals and humans with neuromusculoskeletal conditions. Four electronic databases were searched for controlled trials. Two reviewers independently selected studies, extracted data, assessed the risk of bias, and graded the certainty of the evidence. Where possible, meta-analyses using random effects models were used to pool the results. Preliminary evidence from 13 animal studies report neuroimmune responses after joint and nerve mobilisations. In neuropathic pain models, meta-analysis revealed decreased spinal cord levels of glial fibrillary acidic protein, dorsal root ganglion levels of interleukin-1β, number of dorsal root ganglion nonneuronal cells, and increased spinal cord interleukin-10 levels. The 5 included human studies showed mixed effects of spinal manipulation on salivary/serum cortisol levels in people with spinal pain, and no significant effects on serum β-endorphin or interleukin-1β levels in people with spinal pain. There is evidence that joint and nerve mobilisations positively influence various neuroimmune responses. However, as most findings are based on single studies, the certainty of the evidence is low to very low. Further studies are needed.

Do behaviour change techniques increase adherence to home exercises in those with upper extremity musculoskeletal disorders? A systematic review

OBJECTIVES

To investigate whether behaviour change techniques (BCTs) can influence adherence to home exercise in people with upper extremity musculoskeletal disorders (UEMD).

DESIGN

A systematic review of randomised control trials, non-randomised control trials, case-control studies and cohort studies. Results were presented narratively. Participants were those with UEMD. The intervention was any home exercise programme, alongside a BCT designed to increase exercise adherence. Any duration of intervention was accepted. The main outcome sought was adherence to home exercise. A systematic search was performed on four online databases. Grey literature was searched.

RESULTS

The search resulted in 28,755 titles. 77 full-text articles were assessed for eligibility. Six studies were included in the qualitative synthesis. Four studies had Some Concern of Bias, whilst two studies had High Risk of Bias. Three studies found statistically significant differences in exercise adherence (p < 0.05) between the Intervention group and Control group. The BCT 'Social Support (unspecified)' was used within all studies that found significant differences in adherence levels at outcome. However, multiple BCTs were received by the Intervention groups within all studies, making it impossible to identify the effects of any single BCT upon adherence levels.

CONCLUSION

Social support may be relevant in patients' adherence levels to HEPs. However, confidence in the results is uncertain given the small number of studies found, and their High RoB. Future studies should validate their measurement and definition of adherence, as well as the number of BCTs they use, to provide reproducible evidence.

Effect of Neural Mobilization on Nerve-Related Neck and Arm Pain: A Randomized Controlled Trial

Purpose: Neural mobilization (NM) is often used to treat nerve-related conditions, and its use is reasonable with nerve-related neck and arm pain (NNAP). The aims of this study were to establish the effect of NM on the pain, function, and quality of life (QOL) of patients with NNAP and to establish whether high catastrophizing and neuropathic pain influence treatment outcomes. Method: A randomized controlled trial compared a usual-care (UC; n = 26) group, who received cervical and thoracic mobilization, exercises, and advice, with an intervention (UCNM; n = 60) group, who received the same treatment but with the addition of NM. Soft tissue mobilization along the tract of the nerve was used as the NM technique. The primary outcomes were pain intensity (rated on the Numerical Pain Rating Scale), function (Patient-Specific Functional Scale), and QOL (EuroQol-5D) at 3 weeks, 6 weeks, 6 months, and 12 months. The secondary outcomes were the presence of neuropathic pain (using the Neuropathic Diagnostic Questionnaire) and catastrophizing (Pain Catastrophising Scale). Results: Both groups improved in terms of pain, function, and QOL over the 12-month period (p < 0.05). No between-groups differences were found at 12 months, but the UCNM group had significantly less pain at 6 months (p = 0.03). Patients who still presented with neuropathic pain (p < 0.001) and high pain catastrophizing (p = 0.02) at 6- and 12-mo follow-ups had more pain. Conclusions: Both groups had similar improvements in function and QOL at 12-month follow-up. The UCNM group had significantly less pain at 6-month follow-up and a lower mean pain rating at 12-month follow-up, although the difference between groups was not significant. Neuropathic pain is common among this population and, where it persisted, patients had more pain and functional limitations at 12-mo follow-up.

Cervical traction combined with neural mobilization for patients with cervical radiculopathy: A randomized controlled trial

BACKGROUND

Although both neural mobilization (NM) and cervical traction (CT) are widely used interventions in cervical radiculopathy (CR), there is limited clinical data to support their use.

OBJECTIVE

To evaluate the effects of CT, with or without the addition of NM, on pain, function, and disability in patients with CR.

DESIGN

A randomized, double-blinded, placebo-controlled clinical trial.

METHODS

66 patients with CR were randomly allocated to: a group (n = 22) received CT combined with NM (CT + NM), a group (n = 22) received CT combined with sham NM (CT + shamNM) and a wait-list control (WLC) group (n = 22). The Neck Disability Index (NDI), the Patient-Specific Functional Scale, the Numeric Pain Rating Scale (NPRS), grip strength and cervical spine mobility were used as outcome measures. A two-way analysis of variance was used to evaluate differences between the three groups at baseline and at 4-week follow-up.

RESULTS

Statistically and clinically significant between-group differences at 4-week follow-up were found between CT + NM and WLC groups in favor of CT + NM group in NDI scores (d = 1.30), NRPS (d = 1.94), and active cervical rotation towards the opposite arm (d = 1.18) and between CT + NM and CT + shamNM groups in favor of CT + NM group in NRPS (d = 1.21). No significant differences were observed between CT + shamNM and WLC groups in all outcome measures. Clinically significant within-group improvements were found only for the CT + NM group.

CONCLUSION

At 4-week follow-up, CT in combination with NM resulted in improved outcomes in pain, function and disability in patients with CR.

Physiotherapy for people with painful peripheral neuropathies: a narrative review of its efficacy and safety

Pharmacological treatment for peripheral neuropathic pain has only modest effects and is often limited by serious adverse responses. Alternative treatment approaches including physiotherapy management have thus gained interest in the management of people with peripheral neuropathies. This narrative review summarises the current literature on the efficacy and safety of physiotherapy to reduce pain and disability in people with radicular pain and chemotherapy-induced peripheral neuropathy, 2 common peripheral neuropathies. For chemotherapy-induced peripheral neuropathy, the current evidence based on 8 randomised controlled trials suggests that exercise may reduce symptoms in patients with established neuropathy, but there is a lack of evidence for its preventative effect in patients who do not yet have symptoms. For radicular pain, most of the 21 trials investigated interventions targeted at improving motor control or reducing neural mechanosensitivity. The results were equivocal, with some indication that neural tissue management may show some benefits in reducing pain. Adverse events to physiotherapy seemed rare; however, these were not consistently reported across all studies. Although it is encouraging to see that the evidence base for physiotherapy in the treatment of peripheral neuropathic pain is growing steadily, the mixed quality of available studies currently prevents firm treatment recommendations. Based on promising preliminary data, suggestions are made on potential directions to move the field forward.

Neural gliding and neural tensioning differently impact flexibility, heat and pressure pain thresholds in asymptomatic subjects: A randomized, parallel and double-blind study

OBJECTIVE

To compare the effect of neural gliding and tensioning on hamstring flexibility, nerve function (heat and cold thresholds) and pain sensitivity (pain intensity and pressure pain threshold) of the mobilized and non-mobilized lower limbs at post-intervention and 24 h follow up.

DESIGN

Randomized, parallel and double blinded trial.

SETTING/PARTICIPANTS

Forty-eight asymptomatic participants.

INTERVENTION(S)

Participants received neural gliding (n = 23) or tensioning (n = 25). Main Outcome Measures - Straight leg raising (SLR; in degrees), heat and cold threshold (ºC), pressure pain threshold (PPT; in Kgf) and pain intensity (visual analogue scale), taken at baseline, post-intervention and at 24 h follow up.

RESULTS

There was a significant interaction between time, intervention and limb for SLR (F2,45 = 3.83; p = 0.029). A significant interaction between time and intervention for PPT (F2,45 = 3.59; p = 0.036) and heat threshold (F2,45 = 5.10; p = 0.01). A significant effect of time (F2,45 = 9.42; p < 0.001) and of limb (F1,46 = 4.78; p = 0.035) for pain intensity during SLR, and a significant effect of time (F2,45 = 3.65; p = 0.034) for pain intensity during PPT.

CONCLUSION

Gliding and tensioning had similar and positive effects for flexibility in the mobilized limb, but tensioning was superior for the non-mobilized limb. Gliding was superior to tensioning for pressure pain and heat thresholds.

Neurotrophin expression and histomorphometric evaluation in Wistar rats subjected to neural mobilization after compression of the median nerve

OBJECTIVE

To evaluate the neurotrophin mRNA expression and axon count in the median nerve of Wistar rats submitted to neural mobilization (NM) after nerve compression.

METHODS

Eighteen animals were randomly divided into G1 (nerve compression only), G2 (NM for 1 min), and G3 (NM for 3 min). For NM, the animals were anesthetized and the right scapula received the mobilization, adapted as indicated for humans, on alternate days, from the third to the 13th postoperative (PO) day, totaling six days of therapy. On the 14th PO day, animals were anesthetized and euthanized. Fragments of the median nerve, distal to the compression procedure, were removed for histomorphometric analysis and expression of neurotrophins, nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF) by RT-PCR.

RESULTS

Histomorphometric analysis revealed differences in the number of axons in the injured side, which was significantly lower in the injured limb nerve compared to the control limb, whereas the RT-PCR analysis showed no significant differences in the expression of NGF or BDNF.

CONCLUSION

NM treatment did not affect median nerve regeneration, which maintained normal recovery rates.

Short-term swimming exercise attenuates the sensitization of dorsal horn neurons in rats with NGF-induced low back pain

BACKGROUND

Physical exercise has been shown to be an effective therapy for non-specific low back pain. The study investigated if swimming exercise is a means to reduce the spinal sensitization in an animal model of non-specific low back pain.

METHODS

In deeply anesthetized rats, dorsal horn neurons were recorded in spinal segment L2. To induce sensitization of dorsal horn neurons, two injections of nerve growth factor were made into the lumbar multifidus muscle at an interval of 5 days. Swimming exercise for 30 min was performed on the 5 days between both NGF injections. A control group received the NGF injections without exercise treatment.

RESULTS

Swimming exercise caused a significant decrease in the NGF-induced hyperexcitability of dorsal horn neurons. Compared to control, the proportion of neurons with input from deep somatic tissues and of convergent neurons with input from at least two types of different tissues decreased significantly (50% vs. 25% and 37% vs. 15%; both p < 0.05). Swimming exercise also reduced the NGF-induced increase in neuronal resting activity. Both the proportion of active neurons and the mean discharge frequency of all neurons decreased significantly (60%, 76.3 ± 23.1 imp/min; vs. 25%, 51.7 ± 35.1 imp/min; both p < 0.01).

CONCLUSIONS

In our animal model of low back pain, short-term swimming exercise effectively reduced the latent sensitization of spinal dorsal horn neurons. Swimming exercise decreased the hyperexcitability of the neurons to low back input and lowered the resting activity of sensitized neurons.

SIGNIFICANCE

Physical exercise is a common treatment for low back pain. The possible mechanisms underlying the effects of exercise are probably multifold. This work shows that swimming exercise prevents sensitization of dorsal horn neurons, which may be one mechanism for the positive effects of exercise.

Neural Mobilization Attenuates Mechanical Allodynia and Decreases Proinflammatory Cytokine Concentrations in Rats With Painful Diabetic Neuropathy

BACKGROUND

Painful diabetic neuropathy (PDN) is a common complication in patients with diabetes. It is related to ischemic nerve damage and the increase in the levels of proinflammatory mediators, such as tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Neural mobilization may have the potential to alleviate PDN, but it has not yet been tested. Also, the physiological mechanism of neural mobilization is unclear.

OBJECTIVE

The objective of this study was to investigate treatment effect and physiological mechanism of neural mobilization.

DESIGN

This was an experimental study using rats with streptozocin (or streptozotocin)-induced type 1 diabetes.

METHODS

Three groups were used in the study, the control group (vehicle), the diabetes group (PDN group), and the neural mobilization treatment group (PDN-NM group) (n = 6). Rats in the vehicle group were healthy rats. Rats in the PDN and PDN-NM groups were rats with diabetes. Rats in the PDN-NM group received treatment in the right sciatic nerve, whereas rats in the PDN group did not. Mechanical pain sensitivity and the levels of IL-1β and TNF-α in the sciatic nerve branches and trunk, the L4 to L6 dorsal horn ganglion, and the spinal cord dorsal horn were measured.

RESULTS

Techanical allodynia was alleviated after treatment, but the effect was limited to the treatment side. The concentrations of proinflammatory cytokines were decreased in the nerves that received treatment compared with those on the other side, indicating that neural mobilization may reduce mechanical sensitivity by decreasing the concentrations of local sensitizing agents.

LIMITATIONS

A limitation of this study was that no direct measurement of nerve blood flow was done.

CONCLUSIONS

The results of this study showed that neural mobilization effectively alleviated mechanical allodynia in rats with PDN. The side that received treatment had lower concentrations of TNF-α and IL-1β in the sciatic nerve branches and sciatic nerve trunk; this result may have been related to the alleviation of mechanical allodynia.

Non-pharmacological treatment affects neuropeptide expression in neuropathic pain model

Chronic constriction injury (CCI) of the sciatic nerve elicits changes in neuropeptide expression on the dorsal root ganglia (DRG). The neural mobilization (NM) technique is a noninvasive method that has been proven clinically effective in reducing pain. The aim of this study was to analyze the expression of substance P, transient receptor potential vanilloid 1 (TRPV1) and opioid receptors in the DRG of rats with chronic constriction injury and to compare it to animals that received NM treatment. CCI was performed on adult male rats. Each animal was submitted to 10 sessions of neural mobilization every other day, starting 14 days after the CCI injury. At the end of the sessions, the DRG (L4-L6) were analyzed using Western blot assays for substance P, TRPV1 and opioid receptors (µ-opioid receptor, δ-opioid receptor and κ-opioid receptor). We observed a decreased substance P and TRPV1 expression (48% and 35%, respectively) and an important increase of µ-opioid receptor expression (200%) in the DRG after NM treatment compared to control animals. The data provide evidence that NM promotes substantial changes in neuropeptide expression in the DRG; these results may provide new options for treating neuropathic pain.

Entrapment Neuropathies: Challenging Common Beliefs With Novel Evidence

Entrapment neuropathies are the most prevalent type of peripheral neuropathy and often a challenge to diagnose and treat. To a large extent, our current knowledge is based on empirical concepts and early (often biomechanical) studies. This Viewpoint will challenge some of the current beliefs with recent advances in both basic and clinical neurosciences. J Orthop Sports Phys Ther 2018;48(2):58-62. doi:10.2519/jospt.2018.0603.

Systemic administration of vitamins C and E attenuates nociception induced by chronic constriction injury of the sciatic nerve in rats

Antioxidants have been tested to treat neuropathic pain, and α-Tocopherol (vitamin E--vit. E) and ascorbic acid (vitamin C--vit. C) are potent antioxidants. We assessed the effect of intraperitoneal administration of vit. C (30 mg/kg/day) and vit. E (15 mg/kg/day), given alone or in combination, on the mechanical and thermal thresholds and the sciatic functional index (SFI) in rats with chronic constriction injury (CCI) of the sciatic nerve. We also determined the lipid hydroperoxides and total antioxidant capacity (TAC) in the injured sciatic nerve. Further, we assessed the effects of oral administration of vit. C+vit. E (vit. C+E) and of a combination of vit. C+E and gabapentin (100mg/kg/day, i.p.) on the mechanical and thermal thresholds of CCI rats. The vitamins, whether administered orally or i.p., attenuated the reductions in the mechanical and thermal thresholds induced by CCI. The antinociceptive effect was greater with a combination of vit. C+E than with each vitamin given alone. The SFI was also improved in vitamin-treated CCI rats. Co-administration of vit. C+E and gabapentin induced a greater antinociceptive effect than gabapentin alone. No significant change occurred in TAC and lipid hydroperoxide levels, but TAC increased (45%) while lipid hydroperoxides decreased (38%) in the sciatic nerve from vit. C+E-treated CCI rats. Thus, treatment with a combination of vit. C+E was more effective to treat CCI-induced neuropathic pain than vitamins alone, and the antinociceptive effect was greater with co-administration of vit. C+E and gabapentin than with gabapentin alone.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

The Role of Descending Modulation in Manual Therapy and Its Analgesic Implications: A Narrative Review

Manual therapy has long been a component of physical rehabilitation programs, especially to treat those in pain. The mechanisms of manual therapy, however, are not fully understood, and it has been suggested that its pain modulatory effects are of neurophysiological origin and may be mediated by the descending modulatory circuit. Therefore, the purpose of this review is to examine the neurophysiological response to different types of manual therapy, in order to better understand the neurophysiological mechanisms behind each therapy's analgesic effects. It is concluded that different forms of manual therapy elicit analgesic effects via different mechanisms, and nearly all therapies appear to be at least partially mediated by descending modulation. Additionally, future avenues of mechanistic research pertaining to manual therapy are discussed.