Resveratrol attenuates neuropathic pain through balancing pro-inflammatory and anti-inflammatory cytokines release in mice

Therapeutic Advances in Peripheral Nerve Injuries: Nerve-Guided Conduit and Beyond

Peripheral nerve injury (PNI), a challenging neurosurgery issue, often leads to partial or complete loss of neuronal functions and even neuropathic pain. Thus far, the gold standard for treating peripheral nerve deficit remains autografts. While numerous reviews have explored PNI and regeneration, this work distinctively synthesizes recent advancements in tissue engineering-particularly four-dimensional (4D) bioprinting and exosome therapies-with an emphasis on their clinical translation. By consolidating findings spanning molecular mechanisms to therapeutic applications, this review proposes an actionable framework for advancing experimental strategies toward clinically viable solutions. Our work critically evaluates emerging innovations such as dynamically adaptive 4D-printed nerve conduits and exosome-based therapies, underscoring their potential to match conventional autografts in achieving functional restoration. Impact Statement Although several previous reviews have been made on describing with great detail the degenerative and regenerative mechanisms of the peripheral nervous systems, as well as the several existing and exploratory treatment strategies, we focus more on the latest advancements of each of those topics.

The circadian rhythm: A new target of natural products that can protect against diseases of the metabolic system, cardiovascular system, and nervous system

BACKGROUND

The treatment of metabolic system, cardiovascular system, and nervous system diseases remains to be explored. In the internal environment of organisms, the metabolism of substances such as carbohydrates, lipids and proteins (including biohormones and enzymes) exhibit a certain circadian rhythm to maintain the energy supply and material cycle needed for the normal activities of organisms. As a key factor for the health of organisms, the circadian rhythm can be disrupted by pathological conditions, and this disruption accelerates the progression of diseases and results in a vicious cycle. The current treatments targeting the circadian rhythm for the treatment of metabolic system, cardiovascular system, and nervous system diseases have certain limitations, and the identification of safer and more effective circadian rhythm regulators is needed.

AIM OF THE REVIEW

To systematically assess the possibility of using the biological clock as a natural product target for disease intervention, this work reviews a range of evidence on the potential effectiveness of natural products targeting the circadian rhythm to protect against diseases of the metabolic system, cardiovascular system, and nervous system. This manuscript focuses on how natural products restore normal function by affecting the amplitude of the expression of circadian factors, sleep/wake cycles and the structure of the gut microbiota.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

This work proposes that the circadian rhythm, which is regulated by the amplitude of the expression of circadian rhythm-related factors and the sleep/wake cycle, is crucial for diseases of the metabolic system, cardiovascular system and nervous system and is a new target for slowing the progression of diseases through the use of natural products. This manuscript provides a reference for the molecular modeling of natural products that target the circadian rhythm and provides a new perspective for the time-targeted action of drugs.

The Role of Phytochemicals in Managing Neuropathic Pain: How Much Progress Have We Made?

Neuropathic pain is a complex and debilitating condition resulting from nerve damage, characterized by sensations such as burning, tingling, and shooting pain. It is often associated with conditions such as multiple sclerosis (MS), Guillain-Barré syndrome (GBS), and diabetic polyneuropathy. Conventional pain therapies frequently provide limited relief and are accompanied by significant side effects, emphasizing the need to explore alternative treatment options. Phytochemicals, which are bioactive compounds derived from plants, have gained attention for their potential in neuropathic pain management due to their diverse pharmacological properties, including anti-inflammatory, antioxidant, and neuroprotective effects. This review evaluates the mechanisms by which specific phytochemicals, such as curcumin, resveratrol, and capsaicin, influence neuropathic pain pathways, particularly their role in modulating inflammatory processes, reducing oxidative stress, and interacting with ion channels and signaling pathways. While curcumin and resveratrol are primarily considered dietary supplements, their roles in managing neuropathic pain require further clinical investigation to establish their efficacy and safety. In contrast, capsaicin is an active ingredient derived from chili peppers that has been developed into approved topical treatments widely used for managing neuropathic and musculoskeletal pain. However, not all phytochemicals have demonstrated consistent efficacy in managing neuropathic pain, and their effects can vary depending on the compound and the specific condition. The pathophysiology of neuropathic pain, involving maladaptive changes in the somatosensory nervous system, peripheral and central sensitization, and glial cell activation, is also outlined. Overall, this review emphasizes the need for continued high-quality clinical studies to fully establish the therapeutic potential of phytochemicals in neuropathic pain management.

Recent advances in small molecule Nav 1.7 inhibitors for cancer pain management

The dorsal root ganglion (DRG) is the primary neuron responsible for transmitting peripheral pain signals to the central nervous system and plays a crucial role in pain transduction. Modulation of DRG excitability is considered a viable approach for pain management. Neuronal excitability is intricately linked to the ion channels on the neurons. The small and medium-sized DRG neurons are chiefly engaged in pain conduction and have high levels of TTX-S sodium channels, with Nav1.7 accounting for approximately 80% of the current. Voltage-gated sodium channel (VGSC or Nav) blockers are vital targets for the management of central nervous system diseases, particularly chronic pain. VGSCs play a key role in controlling cellular excitability. Clinical research has shown that Nav1.7 plays a crucial role in pain sensation, and there is strong genetic evidence linking Nav1.7 and its encoding gene SCN9A gene to painful disorders in humans. Many studies have shown that Nav1.7 plays an important role in pain management. The role of Nav1.7 in pain signaling pathways makes it an attractive target for the potential development of new pain drugs. Meanwhile, understanding the architecture of Nav1.7 may help to develop the next generation of painkillers. This review provides updates on the recently reported molecular inhibitors targeting the Nav1.7 pathway, summarizes their structure-activity relationships (SARs), and discusses their therapeutic effects on painful diseases. Pharmaceutical chemists are working to improve the therapeutic index of Nav1.7 inhibitors, achieve better analgesic effects, and reduce side effects. We hope that this review will contribute to the development of novel Nav1.7 inhibitors as potential drugs.

High-voltage pulsed radiofrequency improves ultrastructure of DRG and enhances spinal microglial autophagy to ameliorate neuropathic pain induced by SNI

Neuropathic pain (NeP) is intractable for which many therapies are ineffective. High-voltage pulsed radiofrequency (HVPRF) on dorsal root ganglion (DRG) is considered an effective treatment for NeP. The aim of this study is to explore the therapeutic voltage for the optimal efficacy of PRF and the underlying mechanisms. The radiofrequency electrode was placed close to the L5 DRG of rats with spared nerve injury (SNI) and emitted current by the corresponding voltage in different groups. Four different voltages (45 V, 65 V, 85 V, and 100 V) of PRF on DRG significantly alleviated the SNI-induced NeP, reduced the levels of activating transcription factor 3 (ATF3) in DRG, improved the ultrastructure of DRG, and promoted autophagy in spinal microglia to varying degrees and partially reversed the increased expression of TNF-α and the reduced expression of IL-10 in spinal cord dorsal horn (SCDH). The beneficial effect of 85V-PRF was superior to those of other three PRF treatments. The underlying mechanisms may be related to repairing the DRG damage and improving the DRG ultrastructure while regulating spinal microglial autophagy and thereby alleviating neuroinflammation.

Deciphering resveratrol's role in modulating pathological pain: From molecular mechanisms to clinical relevance

Pathological pain, a multifaceted and debilitating ailment originating from injury or post-injury inflammation of the somatosensory system, poses a global health challenge. Despite its ubiquity, reliable therapeutic strategies remain elusive. To solve this problem, resveratrol, a naturally occurring nonflavonoid polyphenol, has emerged as a potential beacon of hope owing to its anti-inflammatory, antioxidant, and immunomodulatory capabilities. These properties potentially position resveratrol as an efficacious candidate for the management of pathological pain. This concise review summaries current experimental and clinical findings to underscore the therapeutic potential of resveratrol in pathological pain, casting light on the complex underlying pathophysiology. Our exploration suggests that resveratrol may exert its analgesic effect by the modulating pivotal signaling pathways, including PI3K/Akt/mTOR, TNFR1/NF-κB, MAPKs, and Nrf2. Moreover, resveratrol appears to attenuate spinal microglia activation, regulate primary receptors in dorsal root sensory neurons, inhibit pertinent voltage-gated ion channels, and curb the expression of inflammatory mediators and oxidative stress responses. The objective of this review is to encapsulate the pharmacological activity of resveratrol, including its probable signaling pathways, pharmacokinetics, and toxicology pertinent to the treatment of pathological pain. Hopefully, we aim to map out promising trajectories for the development of resveratrol as a potential analgesic.

Combined Rehabilitation with Alpha Lipoic Acid, Acetyl-L-Carnitine, Resveratrol, and Cholecalciferolin Discogenic Sciatica in Young People: A Randomized Clinical Trial

Background and Objectives: In the Western world, back pain and sciatica are among the main causes of disability and absence from work with significant personal, social, and economic costs. This prospective observational study aims to evaluate the effectiveness of a rehabilitation program combined with the administration of Alpha Lipoic Acid, Acetyl-L-Carnitine, Resveratrol, and Cholecalciferol in the treatment of sciatica due to herniated discs in young patients in terms of pain resolution, postural alterations, taking painkillers, and quality of life. Materials and Methods: A prospective observational study was conducted on 128 patients with sciatica. We divided the sample into 3 groups: the Combo group, which received a combination of rehabilitation protocol and daily therapy with 600 mg Alpha Lipoic Acid, 1000 mg Acetyl-L-Carnitine, 50 mg Resveratrol, and 800 UI Cholecalciferol for 30 days; the Reha group, which received only a rehabilitation protocol; and the Supplement group, which received only oral supplementation with 600 mg Alpha Lipoic Acid, 1000 mg Acetyl-L-Carnitine, 50 mg Resveratrol, and 800 UI Cholecalciferol. Clinical assessments were made at the time of recruitment (T0), 30 days after the start of treatment (T1), and 60 days after the end of treatment (T2). The rating scales were as follows: the Numeric Rating Scale (NRS); the Oswestry Disability Questionnaire (ODQ); and the 36-item Short Form Health Survey (SF-36). All patients also underwent an instrumental stabilometric evaluation. Results: At T1, the Combo group showed statistically superior results compared to the other groups for pain (p < 0.05), disability (p < 0.05), and quality of life (p < 0.05). At T2, the Combo group showed statistically superior results compared to the other groups only for pain (p < 0.05) and quality of life (p < 0.05). From the analysis of the stabilometric evaluation data, we only observed a statistically significant improvement at T2 in the Combo group for the average X (p < 0.05) compared to the other groups. Conclusions: The combined treatment of rehabilitation and supplements with anti-inflammatory, pain-relieving, and antioxidant action is effective in the treatment of sciatica and can be useful in improving postural stability.

From nature to therapy: Luteolin's potential as an immune system modulator in inflammatory disorders

Inflammation is an essential immune response that helps fight infections and heal tissues. However, chronic inflammation has been linked to several diseases, including cancer, autoimmune disorders, cardiovascular diseases, and neurological disorders. This has increased interest in finding natural substances that can modulate the immune system inflammatory signaling pathways to prevent or treat these diseases. Luteolin is a flavonoid found in many fruits, vegetables, and herbs. It has been shown to have anti-inflammatory effects by altering signaling pathways in immune cells. This review article discusses the current research on luteolin's role as a natural immune system modulator of inflammatory signaling mechanisms, such as its effects on nuclear factor-kappa B, mitogen-activated protein kinases, Janus kinase/signal transducer and activator of transcription, and inflammasome signaling processes. The safety profile of luteolin and its potential therapeutic uses in conditions linked to inflammation are also discussed. Overall, the data point to Luteolin's intriguing potential as a natural regulator of immune system inflammatory signaling processes. More research is needed to fully understand its mechanisms of action and possible therapeutic applications.

Bibliometric and visual analysis of microglia-related neuropathic pain from 2000 to 2021

Background

Microglia has gradually gained researchers' attention in the past few decades and has shown its promising prospect in treating neuropathic pain. Our study was performed to comprehensively evaluate microglia-related neuropathic pain via a bibliometric approach.

Methods

We retrospectively reviewed publications focusing on microglia-related neuropathic pain from 2000 to 2021 in WoSCC. VOS viewer software and CiteSpace software were used for statistical analyses.

Results

A total of 2,609 articles were finally included. A steady increase in the number of relevant publications was observed in the past two decades. China is the most productive country, while the United States shares the most-cited and highest H-index country. The University of London, Kyushu University, and the University of California are the top 3 institutions with the highest number of publications. Molecular pain and Pain are the most productive and co-cited journals, respectively. Inoue K (Kyushu University) is the most-contributed researcher and Ji RR (Duke University) ranks 1st in both average citations per article and H-index. Keywords analyses revealed that pro-inflammatory cytokines shared the highest burst strength. Sex differences, neuroinflammation, and oxidative stress are the emerging keywords in recent years.

Conclusion

In the field of microglia-related neuropathic pain, China is the largest producer and the United States is the most influential country. The signaling communication between microglia and neurons has continued to be vital in this field. Sexual dimorphism, neuroinflammation, and stem-cell therapies might be emerging trends that should be closely monitored.

Through Its Powerful Antioxidative Properties, L-Theanine Ameliorates Vincristine-Induced Neuropathy in Rats

L-theanine (LT), which is a major amino acid found in green tea, was shown to alleviate Vincristine (VCR)-induced peripheral neuropathy and associated neuronal functional changes in rats. To induce peripheral neuropathy, rats were administered VCR at a dose of 100 mg/kg/day intraperitoneally on days 1–5 and 8–12, while control rats received LT at doses of 30, 100, and 300 mg/kg/day intraperitoneally for 21 days or saline solution. Electrophysiological measurements were taken to evaluate the nerve functional loss and recovery through motor and sensory nerve conduction velocities. The sciatic nerve was examined for several biomarkers, including nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), total calcium, IL-6, IL-10, MPO, and caspase-3. The results showed that VCR caused significant hyperalgesia and allodynia in rats; decreased nerve conduction velocity; increased NO and MDA levels; and decreased GSH, SOD, CAT, and IL-10 levels. LT was found to significantly reduce VCR-induced nociceptive pain thresholds, decrease oxidative stress levels (NO, MDA), increase antioxidative strength (GSH, SOD, CAT), and reduce neuroinflammatory activity and apoptosis markers (caspase-3). LT’s antioxidant, calcium homeostasis, anti-inflammatory, anti-apoptotic, and neuroprotective properties make it a potential adjuvant to conventional treatment in VCR-induced neuropathy in rats.

Resveratrol suppresses neuroinflammation to alleviate mechanical allodynia by inhibiting Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway in a rat model of spinal cord injury

Background

Neuropathic pain (NP) is one of intractable complications of spinal cord injury (SCI) and lacks effective treatment. Resveratrol (Res) has been shown to possess potent anti-inflammatory and anti-nociceptive effects. In this study, we investigated the analgesic effect of Res and its underlying mechanism in a rat model of SCI.

Methods

The rat thoracic (T10) spinal cord contusion injury model was established, and mechanical thresholds were evaluated during an observation period of 21 days. Intrathecal administration with Res (300 μg/10 μl) was performed once a day for 7 days after the operation. On postoperative day 7, the expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA) and Real-time quantitative PCR (RT-qPCR), the expression of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway was determined by western blot and RT-qPCR, and the co-labeled phospho-STAT3 (p-STAT3) with neuronal nuclear antigen (NeuN), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adapter molecule 1 (Iba-1) were explored by double immunofluorescence staining in the lumbar spinal dorsal horns. The temporal changes of p-STAT3 were investigated by western blot on the 1st, 3rd, 7th, 14th, and 21st days after the operation.

Results

Intrathecal administration with Res for 7 successive days alleviated mechanical allodynia of rats during the observation period. Meanwhile, treatment with Res suppressed the production of pro-inflammatory factors TNF-α, IL-1β and IL-6, and inhibited the expressions of phospho-JAK2 and p-STAT3 in the lumbar spinal dorsal horns on postoperative day 7. Additionally, the protein expression of p-STAT3 was significantly increased on the 1st day following the operation and remained elevated during the next 21 days, immunofluorescence suggested that the up-regulated p-STAT3 was co-located with glial cells and neurons.

Conclusion

Our current results indicated that intrathecal administration with Res effectively alleviated mechanical allodynia after SCI in rats, and its analgesic mechanism might be to suppress neuroinflammation by partly inhibiting JAK2/STAT3 signaling pathway.

The preventive use of resveratrol increases its antioxidant effect by SIRT1 and subclinical anti-inflammatory action in Neuro-2A cells

Currently, the important role of oxidative stress in the aging process and in neurodegenerative diseases has been highlighted, suggesting the beneficial effect of antioxidants as adjuvant therapy. Resveratrol (RSV) is a polyphenolic compound used in the clinic and has been shown as an antioxidant and anti-inflammatory. Therefore, the objective was to verify neuroprotective and modulating effects of RSV on N2-A cells, pre or post inserted into an oxidative stress environment. For this, two treatment conditions were established: pre-stimulus and post-stimulus. The analysis of AMPK and SIRT1 cell signaling pathways was performed through the chemiluminescence assay using the dorsomorphin and EX527 inhibitors, respectively. The inflammatory profile was also evaluated in these neural cells, through the levels of IL-6, TNF, and IL-10. We observed that RSV in N2-A cells has anti-inflammatory effect and antioxidant property and it mechanism is dependent on the SIRT1 signaling pathway. RSV effects occurs most markedly when cells have been pre-stimulated before inducing an oxidative stress environment. These results are important for conducting more adequate protocols in the medical and nutritional clinic.

Mitochondria and sensory processing in inflammatory and neuropathic pain

Rheumatic diseases, such as osteoarthritis and rheumatoid arthritis, affect over 750 million people worldwide and contribute to approximately 40% of chronic pain cases. Inflammation and tissue damage contribute to pain in rheumatic diseases, but pain often persists even when inflammation/damage is resolved. Mechanisms that cause this persistent pain are still unclear. Mitochondria are essential for a myriad of cellular processes and regulate neuronal functions. Mitochondrial dysfunction has been implicated in multiple neurological disorders, but its role in sensory processing and pain in rheumatic diseases is relatively unexplored. This review provides a comprehensive understanding of how mitochondrial dysfunction connects inflammation and damage-associated pathways to neuronal sensitization and persistent pain. To provide an overall framework on how mitochondria control pain, we explored recent evidence in inflammatory and neuropathic pain conditions. Mitochondria have intrinsic quality control mechanisms to prevent functional deficits and cellular damage. We will discuss the link between neuronal activity, mitochondrial dysfunction and chronic pain. Lastly, pharmacological strategies aimed at reestablishing mitochondrial functions or boosting mitochondrial dynamics as therapeutic interventions for chronic pain are discussed. The evidence presented in this review shows that mitochondria dysfunction may play a role in rheumatic pain. The dysfunction is not restricted to neuronal cells in the peripheral and central nervous system, but also includes blood cells and cells at the joint level that may affect pain pathways indirectly. Pre-clinical and clinical data suggest that modulation of mitochondrial functions can be used to attenuate or eliminate pain, which could be beneficial for multiple rheumatic diseases.

Bioactive compounds for neuropathic pain: An update on preclinical studies and future perspectives

Among different types of chronic pain, neuropathic pain (NP), arising from damage to the nervous system, including peripheral fibers and central neurons, is notoriously difficult to treat and affects 7-10% of the general population. Currently available treatment options for NP are limited and opioid analgesics have severe side effects and can result in opioid use disorder. Recent studies have exhibited the role of dietary bioactive compounds in the mitigation of NP. Here, we assessed the effects of commonly consumed bioactive compounds (ginger, curcumin, omega-3 polyunsaturated fatty acids, epigallocatechin gallate, resveratrol, soy isoflavones, lycopene, and naringin) on NP and NP-related neuroinflammation. Cellular studies demonstrated that these bioactive compounds reduce inflammation via suppression of NF-κB and MAPK signaling pathways that regulate apoptosis/cell survival, antioxidant, and anti-inflammatory responses. Animal studies strongly suggest that these regularly consumed bioactive compounds have a pronounced anti-NP effect as shown by decreased mechanical allodynia, mechanical hyperalgesia, thermal hyperalgesia, and cold hyperalgesia. The proposed molecular mechanisms include (1) the enhancement of neuron survival, (2) the reduction of neuronal hyperexcitability by activation of antinociceptive cannabinoid 1 receptors and opioid receptors, (3) the suppression of sodium channel current, and (4) enhancing a potassium outward current in NP-affected animals, triggering a cascade of chemical changes within, and between neurons for pain relief. Human studies administered in this area have been limited. Future randomized controlled trials are warranted to confirm the findings of preclinical efficacies using bioactive compounds in patients with NP.

Solid Dispersions Incorporated into PVP Films for the Controlled Release of Trans-Resveratrol: Development, Physicochemical and In Vitro Characterizations and In Vivo Cutaneous Anti-Inflammatory Evaluation

Trans-resveratrol can promote various dermatological effects. However, its high crystallinity decreases its solubility and bioavailability. Therefore, solid dispersions have been developed to promote its amorphization; even so, they present as powders, making cutaneous controlled drug delivery unfeasible and an alternative necessary for their incorporation into other systems. Thus, polyvinylpyrrolidone (PVP) films were chosen with the aim of developing a controlled delivery system to treat inflammation and bacterial infections associated with atopic dermatitis. Four formulations were developed: two with solid dispersions (and trans-resveratrol) and two as controls. The films presented with uniformity, as well as bioadhesive and good barrier properties. X-ray diffraction showed that trans-resveratrol did not recrystallize. Fourier-transform infrared spectroscopy (FT-IR) and thermal analysis evidenced good chemical compatibilities. The in vitro release assay showed release values from 82.27 ± 2.60 to 92.81 ± 2.50% (being a prolonged release). In the in vitro retention assay, trans-resveratrol was retained in the skin, over 24 h, from 42.88 to 53.28%. They also had low cytotoxicity over fibroblasts. The in vivo assay showed a reduction in inflammation up to 66%. The films also avoided Staphylococcus aureus’s growth, which worsens atopic dermatitis. According to the results, the developed system is suitable for drug delivery and capable of simultaneously treating inflammation and infections related to atopic dermatitis.

Antioxidant, anti-inflammatory and neuroprotective actions of resveratrol after experimental nervous system insults. Special focus on the molecular mechanisms involved

After different types of acute central nervous system insults, including stroke, subarachnoid haemorrhage and traumatic brain and spinal cord injuries, secondary damage plays a central role in the induction of cell death, neurodegeneration and functional deficits. Interestingly, secondary cell death presents an attractive target for clinical intervention because the temporal lag between injury and cell loss provides a potential window for effective treatment. While primary injuries are the direct result of the precipitating insult, secondary damage involves the activation of pathological cascades through which endogenous factors can exacerbate initial tissue damage. Secondary processes, usually interactive and overlapping, include oxidative stress, neuroinflammation and dysregulation of autophagy, ultimately leading to cell death. Resveratrol, a natural stilbene present at relatively high concentrations in grape skin and red wine, exerts a wide range of beneficial health effects. Within the central nervous system, in addition to its inherent free radical scavenging role, resveratrol increases endogenous cellular antioxidant defences thus modulating multiple synergistic pathways responsible for its antioxidant, anti-inflammatory and anti-apoptotic properties. During the last years, a growing body of in vitro and in vivo evidence has been built, indicating that resveratrol can induce a neuroprotective state and attenuate functional deficits when administered acutely after an experimental injury to the central nervous system. In this review, we summarize the most recent findings on the molecular pathways involved in the neuroprotective effects of this multi target polyphenol, and discuss its neuroprotective potential after brain or spinal cord injuries.

Neuroprotective effect of l-theanine in a rat model of chronic constriction injury of sciatic nerve-induced neuropathic pain

BACKGROUND/PURPOSE

We investigated the protective efficacy of _l-theanine (LT), the major amino acid components of green tea, on chronic constriction injury (CCI) of sciatic nerve-induced neuropathic pain (NP) development and neuronal functional changes in rats.

METHODS

Rats with NP induced by CCI of the left sciatic nerve and sham-operated rats received LT or saline solution, with pain sensitive tests of thermal hyperalgesia and mechanical allodynia. Motor and sensory nerve conduction velocities were measured after surgery. Subsequently, the rats were sacrificed; the sciatic nerve was excised, homogenized, prepared and subjected for estimation of nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), myeloperoxidase (MPO), and caspase-3.

RESULTS

CCI produced a significant increase in hyperalgesia and allodynia, an increase in SFI, a decrease in nerve conduction velocity, increases in NO, MDA, TNF-α, IL-1β, IL-6, MPO, and caspase-3 levels, as well as reduction of GSH, SOD, and CAT in the rat sciatic nerve. LT treatment significantly and dose-dependently alleviated CCI-induced nociceptive pain thresholds and ameliorated abnormal nerve conduction and functional loss in rats with CCI. Moreover, LT treatment reduced NO and MDA levels, increased antioxidative strength, and markedly suppressed the levels of neuroinflammatory and apoptotic markers in injured sciatic nerves.

CONCLUSION

This is the first report on the ameliorative effect of LT in CCI-induced NP in rats. This effect might be attributed to its anti-oxidative, anti-inflammatory, anti-apoptotic, and neuroprotective, thus making it potentially useful as an adjuvant to conventional treatment.

Neuropathic Pain: Biomolecular Intervention and Imaging via Targeting Microglia Activation

Many diseases, including cancer, can lead to neuropathic pain (NP). NP is one of the accompanying symptoms of suffering in many conditions and the life quality of NP patient is seriously affected. Due to complex causes, the effects of clinical treatments have been very unsatisfactory. Many experts have found that neuron-microglia interaction plays an essential role in NP occurrence and development. Therefore, the activation of microglia, related inflammatory mediators and molecular and cellular signaling pathways have become the focus of NP research. With the help of modern functional imaging technology, advanced pre-and clinical studies have been carried out and NP interventions have been attempted by using the different pharmaceuticals and the extracted active components of various traditional herbal medicines. In this communication, we review the mechanism of microglia on NP formation and treatment and molecular imaging technology's role in the clinical diagnosis and evaluation of NP therapies.

Roles of AMPK and Its Downstream Signals in Pain Regulation

Pain is an unpleasant sensory and emotional state that decreases quality of life. A metabolic sensor, adenosine monophosphate-activated protein kinase (AMPK), which is ubiquitously expressed in mammalian cells, has recently attracted interest as a new target of pain research. Abnormal AMPK expression and function in the peripheral and central nervous systems are associated with various types of pain. AMPK and its downstream kinases participate in the regulation of neuron excitability, neuroinflammation and axonal and myelin regeneration. Numerous AMPK activators have reduced pain behavior in animal models. The current understanding of pain has been deepened by AMPK research, but certain issues, such as the interactions of AMPK at each step of pain regulation, await further investigation. This review examines the roles of AMPK and its downstream kinases in neurons and non-neuronal cells, as well as their contribution to pain regulation.

Prospective Pharmacological Potential of Resveratrol in Delaying Kidney Aging

Aging is an unavoidable part of life. The more aged we become, the more susceptible we become to various complications and damages to the vital organs, including the kidneys. The existing drugs for kidney diseases are mostly of synthetic origins; thus, natural compounds with minimal side-effects have attracted growing interest from the scientific community and pharmaceutical companies. A literature search was carried out to collect published research information on the effects of resveratrol on kidney aging. Recently, resveratrol has emerged as a potential anti-aging agent. This versatile polyphenol exerts its anti-aging effects by intervening in various pathologies and multi-signaling systems, including sirtuin type 1, AMP-activated protein kinase, and nuclear factor-κB. Researchers are trying to figure out the detailed mechanisms and possible resveratrol-mediated interventions in divergent pathways at the molecular level. This review highlights (i) the causative factors implicated in kidney aging and the therapeutic aspects of resveratrol, and (ii) the effectiveness of resveratrol in delaying the aging process of the kidney while minimizing all possible side effects.

Differential inhibitory effects of resveratrol on excitotoxicity and synaptic plasticity: involvement of NMDA receptor subtypes

Objectives: The neuroprotective effects of resveratrol against excitatory neurotoxicity have been associated with N-methyl-D-aspartate receptor (NMDAR) inhibition. This study examined the differential inhibitory effects of resveratrol on NMDAR-mediated responses in neuronal cells with different NMDAR subtype composition.Methods: The effects of resveratrol on NMDA-induced cell death and calcium influx in immature and mature rat primary cortical neurons were determined and compared. Moreover, the potencies and efficacies of resveratrol to inhibit NR1/NR2A, NR1/NR2B, NR1/NR2C, and NR1/NR2D NMDAR expressed in HEK 293 cells were evaluated.Results: Resveratrol significantly attenuated NMDA-induced cell death in mature neurons, but not in immature neurons. Resveratrol also concentration-dependently reduced NMDA-induced calcium influx among all NMDAR subtypes, but displayed NR2 subunit selectivity, with a potency rank order of NR2B = NR2D > NR2A = NR2C and an efficacy rank order of NR2B = NR2C > NR2A = NR2D. Data show the stronger inhibitory effects of resveratrol on NR1/NR2B than other subtypes. Moreover, resveratrol did not affect hippocampal long-term potentiation (LTP), but impaired long-term depression (LTD).Discussion: These findings reveal the specific NMDAR modulating profile of resveratrol, providing further insight into potential mechanisms underlying the protective effects of resveratrol on neurological disorders.

Antihypernociceptive and Neuroprotective Effects of the Aqueous and Methanol Stem-Bark Extracts of Nauclea pobeguinii (Rubiaceae) on STZ-Induced Diabetic Neuropathic Pain

The greatest common and devastating complication of diabetes is painful neuropathy that can cause hyperalgesia and allodynia. It can disturb psychosocial functioning by increasing levels of anxiety and depression. This work was designed to evaluate the antihyperalgesic, antidepressant, and anxiolytic-like effects of the aqueous and methanol extracts of Nauclea pobeguinii stem-bark in diabetic neuropathy induced by streptozotocin in mice. Diabetic neuropathy was induced in mice by the intraperitoneal administration of 200 mg/kg streptozotocin (STZ) to provoke hyperglycemia. Nauclea pobeguinii aqueous and methanol extracts at the doses of 150 and 300 mg/kg were administered by oral route, and their effects were evaluated on antihyperalgesic activity (Von Frey filaments, hot plate, acetone, and formalin tests), blood glucose levels, body weight, serum, sciatic nerve proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and sciatic nerve growth factor (IGF and NGF) rates, depression (open field test, forced swimming test, tail suspension test), and anxiety (elevated plus maze, light-dark box test, social interaction). Oral administration of Nauclea pobeguinii stem-bark aqueous and methanol extracts (150 and 300 mg/kg) produced antihyperalgesic, antidepressant, and anxiolytic-like effects in STZ-induced diabetic neuropathic mice. Extracts also triggered a decrease in glycaemia and increased body weight in treated animals. They also significantly (p <0.001) reduced tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6 and significantly (p <0.001) increased nerve growth factor (NGF) and insulin-like growth factor (IGF) in sciatic nerves. The results of this study confirmed that Nauclea pobeguinii aqueous and methanol extracts possess antihyperalgesic, antidepressant, and anxiolytic activities and could be beneficial therapeutic agents.

Resveratrol rescued the pain related hypersensitivity for Cntnap2-deficient mice

Contactin-associated protein-like 2 (CNTNAP2 or CASPR2) is a neuronal transmembrane protein of the neurexin superfamily which is correlated with pain related hypersensitivity. Recent results indicated that the hyperactive phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway may be a promising therapeutic target for pain-related hypersensitivity in patients with dysfunction of CNTNAP2. Resveratrol is one of the most widely studied polyphenols with several beneficial properties. In the present study, we investigated the effects of resveratrol on the pain related hypersensitivity. And we found that the up-regulated phosphorylation of S6 could be suppressed by resveratrol. The nocifensive behavior duration time to heat and chemical algogens stimulation in Cntnap2-deficiency (Cntnap2-/-) mice could be attenuated by resveratrol. Our results indicated that resveratrol could rescue the pain related hypersensitivity for Cntnap2-/- mice may be via mTOR signaling pathway.

Opening eyes to therapeutic perspectives of bioactive polyphenols and their nanoformulations against diabetic neuropathy and related complications

Introduction: Diabetic neuropathy (DN) is one of the major complications arising from hyperglycaemia in diabetic patients. In recent years polyphenols present in plants have gained attention to treat DN. The main advantages associated with them are their action via different molecular pathways to manage DN and their safety. However, they failed to gain clinical attention due to challenges associated with their formulation development such as lipophilicity,poor bioavailability, rapid systemic elimination, and enzymatic degradation.Area covered: This article includes different polyphenols that have shown their potential against DN in preclinical studies and the research carried out towards development of their nanoformulations in order to overcome aforementioned issues.Expert opinion: In this review various polyphenol based nanoformulations such as nanospheres, self-nanoemulsifying drug delivery systems, niosomes, electrospun nanofibers, metallic nanoparticles explored exclusively to treat DN are discussed. However, the literature available related to polyphenol based nanoformulations to treat DN is limited. Moreover, these experiments are limited to preclinical studies. Hence, more focus is required towards  development of nanoformulations using simple and single step process as well as inexpensive and non-toxic excipients so that a stable, scalable, reproducible and non-toxic formulation could be achieved and clinical trials could be initiated.

Activating Sirt1 by resveratrol suppresses Nav1.7 expression in DRG through miR-182 and alleviates neuropathic pain in rats

Neuropathic pain is clinically unsatisfactorily treated because of unclear mechanisms. The present study aims to explore the concrete mechanisms underlying the alleviation of resveratrol-activated silent information regulator 1 (Sirt1) to chronic constriction injury (CCI)-induced neuropathic pain. CCI surgery was conducted to the unilateral sciatic nerve of male Sprague-Dawley rats to induce neuropathic pain experimentally. Resveratrol with or without miR-182 antagomir were administered to CCI rats via intrathecal catheter. Behavioral tests including paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were conducted to explore mechanical allodynia and thermal hyperalgesia. Western blot, qRT-PCR were used to detect the expression levels of Sirt1, miR-182, and Nav1.7 in CCI dorsal root ganglions (DRGs). CCI rats displayed lower PWT and PWL compared with the sham control. Also, the CCI DRGs displayed lower Sirt1 and miR-182 expression as well as higher Nav1.7 expression, which would be almost reversed by resveratrol treatment for 4 successive days. We also found that miR-182 expression inhibition erased the analgesia effect of resveratrol to CCI-induced neuropathic pain possibly through upregulating Nav1.7 expression. In summary, resveratrol alleviated CCI-induced neuropathic pain, possibly through activating Sirt1 to suppress Nav1.7 expression via upregulating miR-182 expression in CCI DRGs.

Resveratrol mediates mechanical allodynia through modulating inflammatory response via the TREM2-autophagy axis in SNI rat model

Background

Neuropathic pain (NeuP) is a chronic and challenging clinical problem, with little effective treatment. Resveratrol has shown neuroprotection by inhibiting inflammatory response in NeuP. Recently, the triggering receptor expressed on myeloid cells 2 (TREM2) expressed by microglia was identified as a critical factor of inflammation in nervous system diseases. In this study, we explored whether resveratrol could ameliorate neuroinflammation and produce anti-mechanical allodynia effects via regulating TREM2 in spared nerve injury rats, as well as investigated the underlying mechanisms.

Methods

A spared nerve injury (SNI) rat model was performed to investigate whether resveratrol could exert anti-mechanical allodynia effects via inhibiting neuroinflammation. To evaluate the role of TREM2 in anti-neuroinflammatory function of resveratrol, lentivirus coding TREM2 was intrathecally injected into SNI rats to activate TREM2, and the pain behavior was detected by the von Frey test. Furthermore, 3-methyladenine (3-MA, an autophagy inhibitor) was applied to study the molecular mechanisms of resveratrol-mediated anti-neuroinflammation using Western blot, qPCR, and immunofluorescence.

Results

The TREM2 expression and number of the microglial cells were significantly increased in the ipsilateral spinal dorsal horn after SNI. We found that intrathecal administration of resveratrol (300ug/day) alleviated mechanical allodynia; obviously enhanced autophagy; and markedly reduced the levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α in the ipsilateral spinal dorsal horn after SNI. Moreover, the number of Iba-1⁺ microglial cells and TREM2 expression were downregulated after resveratrol treatment. Intrathecal administration of lentivirus coding TREM2 and/or 3-MA in those rats induced deficiencies in resveratrol-mediated anti-inflammation, leading to mechanical allodynia that could be rescued via administration of Res. Furthermore, 3-MA treatment contributed to TREM2-mediated mechanical allodynia.

Conclusions

Taken together, these data reveal that resveratrol relieves neuropathic pain through suppressing microglia-mediated neuroinflammation via regulating the TREM2-autophagy axis in SNI rats.

Resveratrol alleviates temporomandibular joint inflammatory pain by recovering disturbed gut microbiota

Patients with temporomandibular disorders (TMDs) often experience persistent facial pain. However, the treatment of TMD pain is still inadequate. In recent years, the disturbance of gut microbiota has been shown to play an important role in the pathogenesis of different neurological diseases including chronic pain. In the present study, we investigated the involvement of gut microbiota in the development of temporomandibular joint (TMJ) inflammation. Intra-temporomandibular joint injection of complete Freund's adjuvant (CFA) was employed to induce TMJ inflammation. Resveratrol (RSV), a natural bioactive compound with anti-inflammatory property, was used to treat the CFA-induced TMJ inflammation. We observed that CFA injection not only induces persistent joint pain, but also causes the reduction of short-chain fatty acids (SCFAs, including acetic acid, propionic acid and butyric acid) in the gut as well as decreases relevant gut bacteria Bacteroidetes and Lachnospiraceae. Interestingly, systemic administration of RSV (i.p.) dose-dependently inhibits CFA-induced TMJ inflammation, reverses CFA-caused reduction of SCFAs and these gut bacteria. Moreover, CFA injection causes blood-brain barrier (BBB) leakage, activates microglia and enhances tumor necrosis factor alpha (TNFα) release in the spinal trigeminal nucleus caudalis (Sp5C). The RSV treatment restores the BBB integrity, inhibits microglial activation and decreases the release of TNFα in the Sp5C. Furthermore, fecal microbiota transplantation with feces from RSV-treated mice significantly diminishes the CFA-induced TMJ inflammation. Taken together, our results suggest that gut microbiome perturbation is critical for the development of TMJ inflammation and that recovering gut microbiome to normal levels could be a new therapeutic approach for treating such pain.

Sex dependent alterations of resveratrol on social behaviors and nociceptive reactivity in VPA-induced autistic-like model in rats

INTRODUCTION

The present study was designed to clarify the effects of resveratrol (RSV) on social behavioral alterations and nociceptive reactivity in valproic acid (VPA)-induced autistic-like model in female and male rats.

METHODS

Pregnant Wistar rats were randomly divided in five groups. Animals received saline, DMSO, VPA, RSV and RSV + VPA. VPA was administered (600 mg/kg, i. p.) on embryonic day 12.5 (E12.5) and pretreatment by resveratrol (3.6 mg/kg, s. c.) was applied on E6.5 until E18.5. All offspring were weaned on postnatal day 21 and the experiments were done in male and female rats on day 60. Social interaction, hot plate and tail flick tests were set out to assess social deficits and pain threshold, respectively. Sociability index (SI), Social novelty index (SNI) and latency time were calculated as the standard indices of social behaviors and pain threshold, respectively.

RESULTS

The results indicated that systemic intraperitoneal administration of VPA (600 mg/kg) significantly decreased SI and SNI in social interaction test (SIT) especially in male rats, indicating the social impairments caused by VPA. RSV (3.6 mg/kg, s. c.) reversed VPA-induced social deficits in male rats, but not in female group. VPA administration resulted in significant increase in latency time in the hot plate and tail flick tests in male rats, whereas it had no such dramatic effect in females. RSV administration in combination with VPA had no significant effect on latency time compared to the valproic acid group in male rats. It is important to note that RSV by itself had no significant effect on SI, SNI and latency time in female and male rats.

CONCLUSION

It can be concluded that valproic acid produces autistic-like behaviors and increases pain threshold in male rats which may be ameliorated at least in part by resveratrol administration. Further studies are needed to elucidate the molecular mechanisms involved in valproic acid and resveratrol-induced effects.

Resveratrol alleviates diabetic mechanical allodynia in rats by downregulating P2X3R

Mechanical allodynia, which develops in patients of diabetes mellitus as a neuropathic manifestation, remains without an effective treatment. The aim of the present study was to investigate the effects and potential mechanisms underlying resveratrol (RES) in a rat model of streptozocin (STZ)‑induced diabetic mechanical allodynia (DMA). The rat model of DMA was established by the administration of an intraperitoneal injection of STZ. From day 8 post‑STZ injection, rats were administered with an intragastric injection of various doses of RES for 14 consecutive days. The von Frey filaments were applied to detect the paw withdrawal threshold and evaluate the analgesic effects of RES. Based on the dose‑effect curve, the ED50 of RES was calculated. Immunofluorescence staining and western blotting were performed to detect the expression of purinergic receptor P2X3 (P2X3R) in the dorsal root ganglion (DRG) and spinal dorsal horn (SDH) following RESED50 treatment. The results indicated that RES significantly alleviated mechanical allodynia in DMA model rats in a dose‑dependent manner. Compared with the control group, the expression of P2X3R in DRG neurons and SDH terminals was markedly decreased following the administration of RESED50 (P<0.05). Collectively, the results indicated that RES displayed a dose‑dependent analgesic effect on DMA model rats. Furthermore, P2X3R expression downregulation in the DRG and SDH may be a mechanism underlying the analgesic effects of RES on DMA‑related behaviors.

Crocin Alleviates Pain Hyperalgesia in AIA Rats by Inhibiting the Spinal Wnt5a/β-Catenin Signaling Pathway and Glial Activation

At present, most of the drugs have little effect on the pathological process of rheumatoid arthritis (RA). Analgesia is an important measure in the treatment of RA and is also one of the criteria to determine the therapeutic effects of the disease. Some studies have found that crocin, a kind of Chinese medicine, can effectively alleviate pain sensitization in pain model rats, but the mechanism is not clear. Emerging evidence indicates that crocin may inhibit the metastasis of lung and liver cancer cells from the breast by inhibiting Wnt/β-catenin and the Wnt signaling pathway is closely related to RA. Wnt5a belongs to the Wnt protein family and was previously thought to be involved only in nonclassical Wnt signaling pathways. Recent studies have shown that Wnt5a has both stimulatory and inhibitory effects on the classical Wnt signaling pathway, and so, Wnt5a has attracted increasing attention. This study demonstrated that crocin significantly increased the mechanical thresholds of adjuvant-induced arthritis (AIA) rats, suggesting that crocin can alleviate neuropathic pain. Crocin significantly decreased the levels of pain-related factors and glial activation. Foxy5, activator of Wnt5a, inhibited the above effects of crocin in AIA rats. In addition, intrathecal injection of a Wnt5a inhibitor significantly decreased hyperalgesia in AIA rats. This research shows that crocin may alleviate neuropathic pain in AIA rats by inhibiting the expression of pain-related molecules through the Wnt5a/β-catenin pathway, elucidating the mechanism by which crocin relieves neuropathic pain and provides a new way of thinking for the treatment of AIA pain.

Mechanisms for Reducing Neuropathic Pain

Injury typically results in the development of neuropathic pain, but the pain normally decreases and disappears in paralleled with wound healing. The pain results from cells resident at, and recruited to, the injury site releasing pro-inflammatory cytokines and other mediators leading to the development of pro-inflammatory environment and causing nociceptive neurons to develop chronic ectopic electrical activity, which underlies neuropathic pain. The pain decreases as some of the cells that induce pro-inflammation, changing their phenotype leading to the blocking the release of pro-inflammatory mediators while releasing anti-inflammatory mediators, and blocking nociceptive neuron chronic spontaneous electrical activity. Often, despite apparent wound healing, the neuropathic pain becomes chronic. This raises the question of how chronic pain can be eliminated. While many of the cells and mediators contributing to the development and maintenance of neuropathic pain are known, a better understanding is required of how the injury site environment can be controlled to permanently eliminate the pro-inflammatory environment and silence the chronically electrically active nociceptive neurons. This paper examines how methods that can promote the transition of the pro-inflammatory injury site to an anti-inflammatory state, by changing the composition of local cell types, modifying the activity of pro- and anti-inflammatory receptors, inducing the release of anti-inflammatory mediators, and silencing the chronically electrically active nociceptive neurons. It also examines the hypothesis that factors released from platelet-rich plasma applied to chronic pain sites can permanently eliminate chronic inflammation and its associated chronic pain.

Resveratrol alleviates nuclear factor-κB-mediated neuroinflammation in vasculitic peripheral neuropathy induced by ischaemia-reperfusion via suppressing endoplasmic reticulum stress

Vasculitic peripheral neuropathy (VPN) arises from an inflammatory obstruction in the blood vessels supplying peripheral nerves and subsequent ischaemic insults, which exhibits the clinical features of neuropathic pain and impaired peripheral nerve function. VPN induced by ischaemia-reperfusion (IR) has been reported to involve nuclear factor-κB (NF-κB)-mediated neuroinflammation. Recent studies have suggested that endoplasmic reticulum (ER) stress has been implicated in the development of peripheral neuropathies. Resveratrol possesses a potent anti-inflammatory capacity. We hypothesized that resveratrol may exert a protective effect against VPN through modulating the interrelated ER stress and NF-κB pathways. Male Sprague-Dawley rats were allocated into five groups: sham, sham + resveratrol 40 mg/kg (R40), IR, IR + R20 and IR + R40. VPN was induced by occluding the right femoral artery for 4 hours followed by reperfusion. Our data have shown that VPN induced by IR led to hind paw mechanical allodynia, heat hyperalgaesia, and impaired motor nerve conduction velocity (MNCV). With resveratrol intervention, the behavioural parameters were improved in a dose-dependent manner and the MNCV levels were increased as well. The molecular data revealed that VPN induced by IR significantly increased the expression of NF-κB as well as the ER stress sensor proteins, protein kinase RNA-like endoplasmic reticulum kinase, inositol-requiring enzyme 1 and activating transcription factor 6 in the sciatic nerves. More importantly, resveratrol significantly attenuated the expression of NF-κB and the ER stress sensor proteins after IR. In conclusion, resveratrol alleviates VPN induced by IR. The mechanisms may involve modulating NF-κB-mediated neuroinflammation via suppressing ER stress.

Pretreatment with resveratrol ameliorate trigeminal neuralgia by suppressing matrix metalloproteinase-9/2 in trigeminal ganglion

Trigeminal neuralgia (TN) is a common type of neuropathic pain whereas the underlying pathogenesis has not been completely elucidated. Recent study suggests that the development of neuroinflammation is responsible for generating and sustaining neuropathic pain. The purpose of our study was to investigate the protective effect of intervening the inflammation in early stages of pain and explore its potential mechanism. MMP-9 and MMP-2 are vital proinflammatory participants and accumulating evidence indicates that they are involved in the early development of neuropathic pain. In this study, we found that MMP-9/2 showed different temporal up regulation in trigeminal ganglion (TG) significantly after chronic constriction injury (CCI) surgery. However, the activation of MMP-9/2 were suppressed by the pretreatment with resveratrol, which delayed and attenuated CCI-induced mechanical allodynia simultaneously. Besides, the expression of proinflammatory cytokines like IL-1β and TNF-α as well as the excessive neuronal activity induced by CCI were suppressed by resveratrol. Moreover, we believed that the inhibition of MMP-9/2 activation and pain sensitization may be related to the TLR-4/NF-κB signaling pathway, which might be negatively regulated by the induction of SOCS3. In conclusion, pretreatment with resveratrol could be an effective approach to alleviate trigeminal neuralgia in early stages via a powerful inhibition on the activation of MMP-9/2 in TG.

The antinociceptive effect of resveratrol in bone cancer pain is inhibited by the Silent Information Regulator 1 inhibitor selisistat

Objectives

To study the antinociceptive effect of single and repeated doses of resveratrol in a bone cancer pain model, and whether this effect is prevented by the Silent Information Regulator 1 (SIRT1) inhibitor selisistat.

Methods

The femoral intercondylar bone of BALB/c mice was injected with 1 000 000 BJ3Z cancer cells. Bone resorption and tumour mass growth (measured by in vivo X-ray and fluorescence imaging), as well as mechanical nociceptive thresholds (von Frey device) and dynamic functionality (rotarod machine), were evaluated during the following 4 weeks. Acute resveratrol (100 mg/kg i.p.) and/or selisistat (10 mg/kg s.c.) were administered on day 14. Chronic resveratrol (100 mg/kg i.p., daily) and/or selisistat (0.5 μg/h s.c., Alzet pump) were administered between days 14 and 20.

Key findings

Tumour growth gradually incremented until day 31, while mechanical hyperalgesia started on day 3 after cancer cell injection. Acute resveratrol increased the mechanical threshold of pain (peaking at 1.5 h), while the dynamic functionality decreased. Chronic resveratrol produced a sustained antinociceptive effect on mechanical hyperalgesia and improved the loss of dynamic functionality induced by the bone cancer tumour. Selisistat prevented all the effects of resveratrol.

Conclusions

Acute and chronic resveratrol induces antinociceptive effect in the model of metastatic osseous oncological pain, an effect that would be mediated by SIRT1 molecular signalling.

Recent development in antihyperalgesic effect of phytochemicals: anti-inflammatory and neuro-modulatory actions

INTRODUCTION

Pain is an unpleasant sensation triggered by noxious stimulation. It is one of the most prevalent conditions, limiting productivity and diminishing quality of life. Non steroidal anti inflammatory drugs (NSAIDs) are widely used as pain relievers in present day practice as pain is mostly initiated due to inflammation. However, due to potentially serious side effects, long term use of these antihyperalgesic drugs raises concern. Therefore there is a demand to search novel medicines with least side effects. Herbal products have been used for centuries to reduce pain and inflammation, and phytochemicals are known to cause fewer side effects. However, identification of active phytochemicals of herbal medicines and clear understanding of the molecular mechanism of their action is needed for clinical acceptance.

MATERIALS AND METHODS

In this review, we have briefly discussed the cellular and molecular changes during hyperalgesia via inflammatory mediators and neuro-modulatory action involved therein. The review includes 54 recently reported phytochemicals with antihyperalgesic action, as per the literature available with PubMed, Google Scholar and Scopus.

CONCLUSION

Compounds of high interest as potential antihyperalgesic agents are: curcumin, resveratrol, capsaicin, quercetin, eugenol, naringenin and epigallocatechin gallate (EGCG). Current knowledge about molecular targets of pain and their regulation by these phytochemicals is elaborated and the scope of further research is discussed.

Kindlin-1 Regulates Astrocyte Activation and Pain Sensitivity in Rats With Neuropathic Pain

BACKGROUND AND OBJECTIVES

Astrocyte activation has been implicated in the pathogenesis of neuropathic pain, but the involvement of kindlin-1 in astrocyte activation and neuropathic pain has not yet been illustrated. Using a chronic constriction injury (CCI) rat model of neuropathic pain, we investigated the expression levels of kindlin-1 during neuropathic pain and the influences of kindlin-1 on regulating pain sensitivity.

METHODS

Neuropathic pain was induced in rats by CCI of the sciatic nerve. Rats were randomly assigned to 4 groups: sham operation, CCI, CCI + kindlin-1 short hairpin RNA (shRNA), and CCI + kindlin-1 groups. Animals in the CCI + kindling-1 shRNA and CCI + kindlin-1 groups were given kindlin-1 shRNA or kindlin-1 virus infection to reduce or overexpress kindlin-1, respectively. Kindlin-1 expression was persistently increased in rats 10 days after CCI. A large proportion of glial fibrillary acidic protein (GFAP)-positive astrocytes expressed kindlin-1 in spinal cord tissues of rats after CCI.

RESULTS

Compared with the sham operation group, CCI animals exhibited increased GFAP expression and GFAP-positive astrocytes in the spinal cord. Down-regulation of kindlin-1 reduced the up-regulation of GFAP in the spinal cord, whereas overexpression of kindlin-1 promoted elevation of GFAP levels. Kindlin-1 silencing elevated the mechanical and thermal pain thresholds of CCI rats (P < 0.05). However, overexpression of kindlin-1 aggravated CCI-induced pain sensitivity.

CONCLUSIONS

Kindlin-1 may regulate pain sensitivity by affecting activated astrocytes in the spinal cord. Inhibition of kindlin-1 may provide a novel paradigm for the management of neuropathic pain.

Indolyl-isoxazolidines attenuate LPS-stimulated pro-inflammatory cytokines and increase survival in a mouse model of sepsis: Identification of potent lead

A library of indolyl-isoxazolidines (6-9) has been synthesized by regio- and stereoselective microwave irradiated 1,3-dipolar cycloadditions of C-(3-indolyl)-N-phenylnitrone (2') with variedly substituted dipolarophiles (3'-5') and screened for their anti-inflammatory activities through inhibition of pro-inflammatory cytokines such as TNF-α and IL-6. Amongst the evaluated compounds (6-9), bicyclic isoxazolidine (9a) was found to exhibit significant inhibitory potential against LPS induced human IL-6 and TNF-α in THP-1 cells. Compound 9a was further assessed for in vivo analgesic and anti-inflammatory activities via acetic acid induced writhing and carrageenan induced paw edema models in mice, respectively. The results showed that compound possesses potent anti-inflammatory-analgesic activity comparable to indomethacin and did not show toxicity up to a 2000 mg kg^-1 dose as evidenced by histopathological studies. Consequently, the most active compound 9a was also evaluated against LPS-induced septic death and exhibited a significant protection in in vivo mouse model. Taken all together, the results suggest that the compound 9a is able to attenuate pro-inflammatory cytokines such as IL-6 and TNF-α; accelerate resolution of inflammation, and also increased survival rate of septic mice. Therefore, these "lead" isoxazolidines can be used as promising candidate for further analgesic/anti-inflammatory drug design and development.

Resveratrol enhances IL-4 receptor-mediated anti-inflammatory effects in spinal cord and attenuates neuropathic pain following sciatic nerve injury

Resveratrol has been showed to relieve neuropathic pain through its anti-inflammatory effects on the peripheral nerve system. However, it is not clear whether resveratrol, especially when administered systemically, is effective in alleviating the peripheral neuropathy-induced imbalance between pro- and anti-inflammatory responses in the central nervous system. To test this, we used a rat neuropathic pain model resulting from chronic constriction injury of the sciatic nerve. Resveratrol (200 mg/kg) or vehicle (dimethylsulfoxide) were administered intraperitoneally once daily for 14 consecutive days after chronic constriction injury. We found that resveratrol attenuated mechanical allodynia and thermal hyperalgesia in rats with chronic constriction injury. After 14 days of resveratrol treatment, expression of several anti-inflammatory cytokine receptors, including IL-1RA and IL-1R2, was increased in the dorsal spinal cord of rats with chronic constriction injury, and IL-4Rα was increased in dorsal spinal cord neurons. Knockdown of IL-4Rα in a neuronal cell line reversed the resveratrol-induced upregulation of IL-1RA and IL-1R2. These results indicate that resveratrol enhances IL-4 receptor-mediated anti-inflammatory responses in the spinal cord and thus might contribute to the alleviation of central sensitization following peripheral nerve injury.

A comprehensive review of the health perspectives of resveratrol

Many natural products present in our diet, including flavonoids, can prevent the progression of cancer and other diseases. Resveratrol, a natural polyphenol present in various fruits and vegetables, plays an important role as a therapeutic and chemopreventive agent used in the treatment of various illnesses. It exhibits effects against different types of cancer through different pathways. It additionally exerts antidiabetic, anti-inflammatory, and anti-oxidant effects in a variety of cell types. Furthermore, the cardiovascular protective capacities of resveratrol are associated with multiple molecular targets and may lead to the development of novel therapeutic strategies for atherosclerosis, ischemia/reperfusion, metabolic syndrome, and heart failure. Accordingly, this article presents an overview of recent developments in the use of resveratrol for the prevention and treatment of different diseases along with various mechanisms. In addition, the present review summarizes the most recent literature pertaining to resveratrol as a chemotherapeutic agent against multiple diseases and provides an assessment of the potential of this natural compound as a complementary or alternative medicine.