A new look at painful diabetic neuropathy

N-acetyl-L-cysteine mitigates diabetes-induced impairments in sciatic nerve

Diabetic neuropathy is a consequence of long-term hyperglycemia. The emergence of neuronal condition is a result of hyperglycemia-induced oxidative stress. In the present study, streptozotocin-induced diabetes exhibited notable decrease in the levels of phospholipids, glycolipids, gangliosides, and triglycerides in the sciatic nerve. The alterations in lipids resulted in increase in cholesterol to phospholipid ratio in sciatic nerve of diabetic animals. This ratio is crucial and determines the rheological properties of membranes and resulted in substantial reduction in the activity of membrane-bound enzymes; Ca2 + ATPase and acetylcholinesterase. Histological examination of the cross-section of the sciatic nerve in diabetic mice revealed axonal atrophy and disarrayed myelin sheath. The potential therapeutic impact of N-acetyl Cysteine (NAC), a powerful antioxidant, on a rat model of diabetic neuropathy was evaluated. NAC was administered to rats in drinking water for a period of 8 weeks. The results indicate that administration of NAC restored lipid composition; ratio of cholesterol to phospholipids, the activity of membrane linked enzymes, and improved the structural defects in sciatic nerve. NAC plays protective role against diabetes-induced alterations in lipid composition in sciatic nerve membranes leading to improvement in structure and function of membranes. Overall, the findings suggest NAC as a potential therapeutic strategy in preventing diabetic neuropathy and other diabetic complications.

Computer-aided diagnostic screening of diabetic peripheral neuropathy using colorimetric membrane analysis

BACKGROUND

The aim of this study was to develop an objective computational solution, including a smartphone app, to evaluate colorimetric quantification of a membrane designed to diagnose small fiber peripheral neuropathies in individual with diabetes. This membrane, SudoPad, was developed to improve diagnostic speed and accuracy, while minimizing patient discomfort.

METHODS

SudoPad is polymeric adhesive membrane made from sodium alginate, glycerol, Alizarin Red S, and sodium carbonate. A pilot study for a clinical trial was conducted with three groups to evaluate the membrane's effectiveness. Statistical analysis focused on calculating positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity, and accuracy.

RESULTS

The SudoPad app demonstrated an PPV of 88.46%, NPV of 85.90%, sensitivity of 67.65% (58,65% to 76,64% - CI 95%), specificity of 95.71% (91,81% to 99,60% - CI 95%) and accuracy of 86.54%. These metrics indicated the system's effectiveness in diagnosing peripheral neuropathies with a significant improvement in diagnostic accuracy.

CONCLUSIONS

The results suggest that SudoPad,a low-cost, biodegradable membrane, could enhance health technologies for diagnosing neuropathies. It offers a faster, accurate, and more comfortable alternative to current diagnostic methods.

Dose dependent relationship of metformin use and diabetic peripheral neuropathy risk in patients with type 2 diabetes mellitus

This study investigated the correlation between metformin use and diabetic peripheral neuropathy (DPN) risk in patients with type 2 diabetes mellitus (T2DM) and its dose-dependent relationship. The study included new-onset T2DM patients from 2002 to 2013. Patients were divided into two groups based on metformin treatment, and DPN risk was assessed at 2- and 5-year follow-ups. After adjusting for various factors, two logistic models, metformin cumulative defined daily dose (cDDD) and metformin treatment intensity (defined daily dose [DDD]/month), evaluated the metformin-DPN risk association. Results showed that patients with metformin cDDD < 300, 300-500, and > 500 had higher DPN risk at both follow-ups. Odds ratios (ORs) and confidence intervals (CIs) for DPN were 1.74 (1.69-1.79), 2.05 (1.81-2.32), and 2.36 (1.34-4.16) at 2 years and 1.63 (1.60-1.65), 1.82 (1.69-1.96), and 2.17 (1.56-3.03) at 5 years. Similarly, patients with < 10, 10-25, and > 25 DDD/month had higher DPN risk at both follow-ups. Metformin use correlated with DPN risk in T2DM patients, with a dose-dependent relationship. Higher metformin cDDD or treatment intensity increased DPN risk. However, the absence of vitamin B12 data limits the understanding of the underlying mechanisms. Well-designed, large-scale studies are required to evaluate the potential risks of metformin therapy for DPN in patients with T2DM.

Unraveling the link between magnesium and diabetic neuropathy: Evidence from in vitro to clinical studies

Diabetic neuropathy (DN) is one of the major complications of diabetes and the most common cause of neuropathic pain. Although the underlying pathological mechanisms remain unclear, several studies have produced conflicting results regarding the link between magnesium (Mg) concentration and DN. This ambiguity raises questions about the potential benefits of Mg supplementation in individuals with DN. Therefore, this comprehensive review summarizes and discusses the evidence from clinical, in vitro, and in vivo studies on the association between Mg and DN. Several findings indicate that Mg depletion is linked to the presence of neuropathy in diabetic patients. Additionally, low Mg concentration may contribute to the onset or worsening of DN by promoting axonal degeneration through various pathways. Furthermore, multiple studies have shown that Mg supplementation can have neuroprotective effects. These findings suggest potential as an alternative or complementary therapy for preventing and treating DN in the future.

Alpha-Lipoic Acid Treatment Reduces the Levels of Advanced End Glycation Products in Type 2 Diabetes Patients with Neuropathy

Background/Objectives: Type 2 diabetes mellitus (T2DM) and its macro- and microvascular complications are major health concerns with multiple factors, like advanced end glycation products (AGEs), in the background. AGEs induce long-lasting functional modification of the proteins and collagen in the vascular wall and nerve tissue. We investigated the effect of alpha-lipoic acid (ALA) treatment on AGEs, soluble AGE receptor (sRAGE), the AGE/sRAGE ratio, and the parameters of endothelial dysfunction and their correlations. Methods: In our 6-month intervention study, 54 T2DM patients with neuropathy treated according to the actual therapeutic guidelines with unchanged oral antidiabetic drugs were included and treated by daily oral administration of 600 mg ALA. A total of 24 gender and age-matched T2DM patients without neuropathy served as controls. Results: In our work, we first demonstrated the attenuating effect of alpha lipoic acid therapy on AGEs in humans (11.89 (9.44-12.88) to 10.95 (9.81-12.82) AU/μg (p = 0.017)). sRAGE levels or the AGEs/sRAGE ratio were not affected by ALA treatment or by the presence of neuropathy. We found a correlation between the changes of AGEs and the improvement of current perception threshold and progranulin levels, and an inverse correlation with the change of asymmetric dimethylarginine. Conclusions: According to our results, ALA decreases AGEs, which may contribute to the clinically well-known beneficial effect in diabetic neuropathy and improvement of endothelial function.

Unraveling the therapeutic potential of Astilbe rivularis Buch.-Ham. ex D. Don in attenuation of diabetic neuropathy in laboratory rats

ETHNOPHARMACOLOGICAL RELEVANCE

Astilbe rivularis Buch.-Ham. ex D. Don is a rare medicinal plant, traditionally employed for treating several disorders. The juice, decoction or powder of the roots, rhizomes, leaves and even the entire plant, are used for managing peptic ulcer, diarrhoea, jaundice, sprains and muscular swellings, bone fracture and dislocation of joints, postpartum bleeding and other menstrual disorders. These conventional medicinal uses make Astilbe rivularis a promising candidate for further research.

AIM OF THE STUDY

This study was designed to explore the neuroprotective potential of hydroethanolic extract of Astilbe rivularis (ARHE) in diabetic neuropathy (DN) in rats.

MATERIALS AND METHODS

GC-MS analysis was used to identify the phytoconstituents present in the plant extract. DN was induced by administration of STZ (55 mg/kg, i.p.), 15 min after NAD (230 mg/kg, i.p.) injection. The rats with fasting blood glucose (FBG) level >250 mg/dl were included in the study. DN was assessed by estimating the level of FBG, lipid profile, and invitro and invivo oxidative stress parameters. Additionally, behavioural parameters like, mechanical hyperalgesia, hot and cold allodynia were estimated to assess diabetic neuropathy. Furthermore, the level of antioxidant enzymes like SOD, GSH, and TBARS in sciatic nerve and inflammatory markers like, TGF-β and IL-6 were measured.

RESULTS

Altogether, 30 phytoconstituents were identified including heptafluorobutyric acid, hexadecanoic acid, and beta-sitosterol depicting antioxidant, antidiabetic, and anticancer properties, respectively. Administration of different doses (100, 200, and 400 mg/kg) of ARHE to diabetic rats attenuated elevated blood glucose level and restored lipid profile, body weight, food and water intake, and antioxidant level. Moreover, elevated level of inflammatory markers like, TGF-β and IL-6 was also found to be attenuated in sciatic nerve. Furthermore, ARHE attenuated the pain response assessed by mechanical hyperalgesia and hot and cold allodynia in diabetic neuropathy rats. ARHE also showed inhibitory activity on ALR enzyme and erythrocyte sorbitol accumulation, and ameliorated oxidative stress. Histopathological study indicated improvement in the architecture of sciatic nerve tissue in diabetic neuropathy rats with the treatment of ARHE.

CONCLUSIONS

Conclusively, hydroethanolic extract of Astilbe rivularis exhibited neuroprotective potential and ameliorated diabetic neuropathy in rats.

Probiotics alleviate painful diabetic neuropathy by modulating the microbiota-gut-nerve axis in rats

Painful diabetic neuropathy (PDN) is one of the most common complications of diabetes. Recent studies suggested that gut microbiota dysbiosis contributes to the development of PDN, but underlying mechanisms remain elusive. In this study, we found decreased probiotics generating bacteria such as Lactobacillus and Bifidobacterium strains in the PDN rats. Supplementation with multiple probiotics for 12 weeks alleviated pain, reversed nerve fiber lesions, and restored neuronal hyperexcitability. Probiotics administration effectively attenuated intestinal barrier impairment, reduced serum lipopolysaccharide and proinflammatory cytokines, and mitigated disruptions in the blood-nerve barrier. Furthermore, probiotics treatment inhibited the activation of the TLR4/MyD88/NF-κB signaling pathway and reduced proinflammatory cytokines in the sciatic nerve of the PDN rats. Together, our findings suggest that gut microbiota dysbiosis participates in PDN pathogenesis, and probiotics offer therapeutic potential via modulating the microbiota-gut-nerve axis.

Type 2 Diabetes Mellitus: A Comprehensive Review of Pathophysiology, Comorbidities, and Emerging Therapies

Humans are perhaps evolutionarily engineered to get deeply addicted to sugar, as it not only provides energy but also helps in storing fats, which helps in survival during starvation. Additionally, sugars (glucose and fructose) stimulate the feel-good factor, as they trigger the secretion of serotonin and dopamine in the brain, associated with the reward sensation, uplifting the mood in general. However, when consumed in excess, it contributes to energy imbalance, weight gain, and obesity, leading to the onset of a complex metabolic disorder, generally referred to as diabetes. Type 2 diabetes mellitus (T2DM) is one of the most prevalent forms of diabetes, nearly affecting all age groups. T2DM is clinically diagnosed with a cardinal sign of chronic hyperglycemia (excessive sugar in the blood). Chronic hyperglycemia, coupled with dysfunctions of pancreatic β-cells, insulin resistance, and immune inflammation, further exacerbate the pathology of T2DM. Uncontrolled T2DM, a major public health concern, also contributes significantly toward the onset and progression of several micro- and macrovascular diseases, such as diabetic retinopathy, nephropathy, neuropathy, atherosclerosis, and cardiovascular diseases, including cancer. The current review discusses the epidemiology, causative factors, pathophysiology, and associated comorbidities, including the existing and emerging therapies related to T2DM. It also provides a future roadmap for alternative drug discovery for the management of T2DM.

Application value of strain elastography and shear wave elastography in patients with type 2 diabetic peripheral neuropathy: a prospective observational study

OBJECTIVE

To evaluate the value of conventional ultrasound (US), strain elastography (SE), and shear wave elastography (SWE) in detecting diabetic peripheral neuropathy (DPN) of the tibial nerve (TN), and to establish a predictive model for the diagnosis of DPN.

METHODS

A total of 32 healthy participants, 34 diabetic patients without DPN, and 36 diabetic patients with DPN were recruited for this study. The TN at the ankle and popliteal fossa were selected for examination. US was used to measure the cross-sectional area (CSA) and perimeter of the TN. Additionally, SE was used to measure the strain ratio (SR) between the TN and the surrounding adipose tissue, and SWE was used to measure the shear wave velocity (SWV) of the TN.

RESULTS

The CSA, perimeter, SR, and SWV of the TN at the ankle were significantly higher in the DPN group compared to both the Non-DPN group and control group (P < .05). Similarly, the TN at the popliteal fossa showed these differences. At the ankle, the CSA, perimeter, SR, and SWV of the TN in patients without DPN were significantly higher than those in the control group (P < .05). At the popliteal fossa, the SR and SWV of the TN in patients without DPN were significantly higher than those in the control group (P < .05). However, the CSA and perimeter of the TN in patients without DPN did not show a statistically significant difference compared to the control group. The area under the curve (AUC) for the diagnosis of DPN using SWE is significantly greater than that of SE and US.

CONCLUSION

US, SE, and SWE could be used to diagnose DPN, and they also have good diagnostic value for sub-clinical DPN. Among these methods, SWE has demonstrated superior diagnostic efficacy. Compared to examining the TN in the popliteal fossa, the ankle level offers a better site for examination.

ADVANCES IN KNOWLEDGE

For diabetic peripheral neuropathy, US, SE, and SWE are all promising diagnostic methods with high clinical utility.

Assessment for Diabetic Neuropathy: Treatment and Neurobiological Perspective

Diabetic neuropathy, also known as diabetic peripheral sensorimotor neuropathy (DPN), is a consequential complexity of diabetes, alongside diabetic nephropathy, diabetic cardiomyopathy, and diabetic retinopathy. It is characterized by signs and symptoms of peripheral nerve damage in diabetes patients after ruling out other causes. Approximately 20% of people with diabetes are affected by this painful and severe condition. The development of diabetic neuropathy is influenced by factors such as impaired blood flow to the peripheral nerves and metabolic issues, including increased polyol pathway activation, myo-inositol loss, and nonenzymatic glycation. The present review article provides a brief overview of the pathological changes in diabetic neuropathy and the mechanisms and types of DPN. Various diagnostic tests and biomarkers are available to assess nerve damage and its severity. Pharmacotherapy for neuropathic pain in diabetic neuropathy is complex. This review will explore current treatment options and potential future developments to improve the quality of life for patients suffering from diabetic neuropathy.

Efficacy and Safety of Ultrasound-Guided Pulsed Radiofrequency Therapy of Stellate Ganglion on Refractory Painful Diabetic Peripheral Neuropathy

Background

The best tool for the management of pain associated with distal symmetric peripheral neuropathy (DSPN) is a matter of debate. Therefore, the study aimed to explore whether ultrasound-guided pulsed radiofrequency (PRF) therapy of the stellate ganglion (SG) in type 2 diabetes mellitus (T2DM) patients with painful DSPN could decrease pain severity and the need for analgesics.

Methods

Fifty-six T2DM patients with refractory painful DSPN were enrolled in this study, who then received bilateral ultrasound-guided PRF therapy of SG. The patients completed visual analog scale (VAS), simplified McGill pain questionnaire (SF-MPQ), Toronto clinical score system (TCSS), sleep duration at night (SDN), pain disability index (PDI), Karnofsky performance status (KPS), and depression screening scale (PHQ-9). After procedures, the degree of perceived pain relief, numbness relief and chills relief of the patients, and side effects were assessed. All patients underwent evaluation after the last procedure at 1, 4, 12 and 24-week follow-up periods.

Results

The postoperative VAS, SF-MPQ, TCSS, PDI and PHQ-9 scores were significantly lower, while the KPS values higher than the preoperative (P<0.05). The postoperative SDN was longer than the preoperative (P<0.05). The degree of perceived pain relief, chills relief, and numbness relief at 4, 12, and 24 weeks were lower than that at 1 week after the procedures (P<0.05). The postoperative rates of administration of analgesic were lower than those of preoperative period (P<0.05). The significant effective rates at 1, 4, 12, and 24 weeks after the procedure were 67.86%, 42.86%, 21.43%, and 17.86% and the total effective rates were 89.29%, 71.43%, 46.43%, and 32.14%. No serious complication was observed.

Conclusion

Ultrasound-guided stellate ganglion PRF therapy can effectively relieve pain and improve the quality of life in T2DM patients with refractory painful DSPN.

Pharmacological Effects of Paeonia lactiflora Focusing on Painful Diabetic Neuropathy

Painful diabetic neuropathy (PDN) is a highly prevalent complication in patients suffering from diabetes mellitus. Given the inadequate pain-relieving effect of current therapies for PDN, there is a high unmet medical need for specialized therapeutic options. In traditional Chinese medicine (TCM), various herbal formulations have been implemented for centuries to relieve pain, and one commonly used plant in this context is Paeonia lactiflora (P. lactiflora). Here, we summarize the chemical constituents of P. lactiflora including their pharmacological mechanisms-of-action and discuss potential benefits for the treatment of PDN. For this, in silico data, as well as preclinical and clinical studies, were critically reviewed and comprehensively compiled. Our findings reveal that P. lactiflora and its individual constituents exhibit a variety of pharmacological properties relevant for PDN, including antinociceptive, anti-inflammatory, antioxidant, and antiapoptotic activities. Through this multifaceted and complex combination of various pharmacological effects, relevant hallmarks of PDN are specifically addressed, suggesting that P. lactiflora may represent a promising source for novel therapeutic approaches for PDN.

Dietary Docosahexaenoic Acid-Rich Supplementation Decreases Neurotoxic Lipid Mediators in Participants with Type 2 Diabetes and Neuropathic Pain

BACKGROUND/OBJECTIVES

There is increasing evidence linking circulating neurotoxic lipids to the progression of chronic neuroinflammatory diseases in the peripheral and central nervous systems. Strategies to modify lipid profiles, such as docosahexaenoic acid (DHA)-rich supplementation, may aid in managing conditions like painful diabetic neuropathy (pDN). In a previous study, we demonstrated that three months of DHA supplementation significantly altered the metabolomic profile of patients with painful diabetic neuropathy (pDN), resulting in symptom improvement. This study investigates whether DHA-rich supplementation reduces neurotoxic lipid mediators associated with pDN in individuals with type 2 diabetes mellitus (T2DM).

METHODS

Forty individuals with type 2 diabetes participated in the "En Balance-PLUS" study, attending weekly lifestyle and nutrition education sessions while receiving daily supplementation of 1000 mg DHA and 200 mg EPA. Pain levels were assessed using the Short-Form McGill Pain Questionnaire (SF-MPQ) at baseline and after three months. Blood serum samples collected at these time points underwent untargeted lipidomic analyses, with ELISA used to evaluate biomarkers of necrosis (MLKL), autophagy (ATG5), and lipid chaperone protein (FABP5).

RESULTS

Untargeted lipidomic analysis revealed that several neurotoxic-associated lipids significantly decreased after DHA-rich supplementation. Also, circulating levels of MLKL were reduced, while protein levels of ATG5 and FABP5 significantly increased.

CONCLUSIONS

The reduction of circulating neurotoxic lipids and increase in neuroprotective lipids following DHA-rich supplementation are consistent with the reported roles of omega-3 polyunsaturated fatty acids (PUFAs) in reducing adverse symptoms associated with neuroinflammatory diseases and painful neuropathy.

MCC950 as a promising candidate for blocking NLRP3 inflammasome activation: A review of preclinical research and future directions

The NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome is a key component of the innate immune system that triggers inflammation and pyroptosis and contributes to the development of several diseases. Therefore, blocking the activation of the NLRP3 inflammasome has therapeutic potential for the treatment of these diseases. MCC950, a selective small molecule inhibitor, has emerged as a promising candidate for blocking NLRP3 inflammasome activation. Ongoing research is focused on elucidating the specific targets of MCC950 as well as assessfing its metabolism and safety profile. This review discusses the diseases that have been studied in relation to MCC950, with a focus on stroke, Alzheimer's disease, liver injury, atherosclerosis, diabetes mellitus, and sepsis, using bibliometric analysis. It then summarizes the potential pharmacological targets of MCC950 and discusses its toxicity. Furthermore, it traces the progression from preclinical to clinical research for the treatment of these diseases. Overall, this review provides a solid foundation for the clinical therapeutic potential of MCC950 and offers insights for future research and therapeutic approaches.

Vascular and nerve biomarkers in thigh skin biopsies differentiate painful from painless diabetic peripheral neuropathy

Background

Identifying distinct mechanisms and biomarkers for painful diabetic peripheral neuropathy (DPN) is required for advancing the treatment of this major global unmet clinical need. We previously provided evidence in calf skin biopsies that disproportion between reduced sensory small nerve fibers and increased blood vessels may distinguish painful from non-painful DPN. We proposed that overexposure of the reduced nerve fibers in DPN to increased hypoxemia-induced vasculature and related algogenic factors, e.g., nerve growth factor (NGF), leads to neuropathic pain. To further investigate this proposed mechanism, we have now studied more proximal thigh skin biopsies, to see if the same disproportion between increased vasculature and decreased nerve fibers generally differentiates painful DPN from painless DPN.

Methods

A total of 28 subjects with type 2 diabetes (T2DM) and 13 healthy volunteers (HV) underwent detailed clinical and neurophysiological assessments, based on the neuropathy composite score of the lower limbs [NIS(LL)] plus 7 tests. T2DM subjects were subsequently divided into three groups: painful DPN (n = 15), painless DPN (n = 7), and no DPN (n = 6). All subjects underwent skin punch biopsy from the upper lateral thigh 20 cm below the anterior iliac spine.

Results

Skin biopsies showed decreased PGP 9.5-positive intraepidermal nerve fiber (IENF) density in both painful DPN (p < 0.0001) and painless DPN (p = 0.001). Vascular marker von Willebrand Factor (vWF) density was markedly increased in painful DPN vs. other groups, including painless DPN (p = 0.01). There was a resulting significant decrease in the ratio of intraepidermal nerve fiber density to vasculature and PGP9.5 to vWF, in painful DPN vs. painless DPN (p = 0.05). These results were similar in pattern to those observed in these HV and T2DM groups previously in distal calf biopsies; however, the increase in vWF was much higher and nerve fiber density much lower in the calf than thigh for painful DPN. Thigh skin vWF density was significantly correlated with several metabolic (waist/hip ratio, HbA1c), clinical (e.g., pain score), and neurophysiological measures.

Conclusion

This study supports our proposal that increased dermal vasculature, and its disproportionate ratio to reduced nociceptors, may help differentiate painful DPN from painless DPN. This disproportion is greater in the distal calf than the proximal thigh skin; hence, neuropathic pain in DPN is length-dependent and first localized to the distal lower limbs, mainly feet.

Establishment and external validation of an early warning model of diabetic peripheral neuropathy based on random forest and logistic regression

OBJECTIVE

The primary objective of this study was to investigate the risk factors for diabetic peripheral neuropathy (DPN) and to establish an early diagnostic prediction model for its onset, based on clinical data and biochemical indices.

METHODS

Retrospective data were collected from 1,446 diabetic patients at the First Affiliated Hospital of Anhui University of Chinese Medicine and were split into training and internal validation sets in a 7:3 ratio. Additionally, 360 diabetic patients from the Second Affiliated Hospital were used as an external validation cohort. Feature selection was conducted within the training set, where univariate logistic regression identified variables with a p-value < 0.05, followed by backward elimination to construct the logistic regression model. Concurrently, the random forest algorithm was applied to the training set to identify the top 10 most important features, with hyperparameter optimization performed via grid search combined with cross-validation. Model performance was evaluated using ROC curves, decision curve analysis, and calibration curves. Model fit was assessed using the Hosmer-Lemeshow test, followed by Brier Score evaluation for the random forest model. Ten-fold cross-validation was employed for further validation, and SHAP analysis was conducted to enhance model interpretability.

RESULTS

A nomogram model was developed using logistic regression with key features: limb numbness, limb pain, diabetic retinopathy, diabetic kidney disease, urinary protein, diastolic blood pressure, white blood cell count, HbA1c, and high-density lipoprotein cholesterol. The model achieved AUCs of 0.91, 0.88, and 0.88 for the training, validation, and test sets, respectively, with a mean AUC of 0.902 across 10-fold cross-validation. Hosmer-Lemeshow test results showed p-values of 0.595, 0.418, and 0.126 for the training, validation, and test sets, respectively. The random forest model demonstrated AUCs of 0.95, 0.88, and 0.88 for the training, validation, and test sets, respectively, with a mean AUC of 0.886 across 10-fold cross-validation. The Brier score indicates a good calibration level, with values of 0.104, 0.143, and 0.142 for the training, validation, and test sets, respectively.

CONCLUSION

The developed nomogram exhibits promise as an effective tool for the diagnosis of diabetic peripheral neuropathy in clinical settings.

Discovery and Profiling of New Multimodal Phenylglycinamide Derivatives as Potent Antiseizure and Antinociceptive Drug Candidates

We developed a focused series of original phenyl-glycinamide derivatives which showed potent activity across in vivo mouse seizure models, namely, maximal electroshock (MES) and 6 Hz (using both 32 and 44 mA current intensities) seizure models. Following intraperitoneal (i.p.) administration, compound (R)-32, which was identified as a lead molecule, demonstrated potent protection against all seizure models with ED50 values of 73.9 mg/kg (MES test), 18.8 mg/kg (6 Hz, 32 mA test), and 26.5 mg/kg (6 Hz, 44 mA test). Furthermore, (R)-32 demonstrated efficacy in both the PTZ-induced kindling paradigm and the ivPTZ seizure threshold test. The expression of neurotrophic factors, such as mature brain-derived neurotrophic factor (mBDNF) and nerve growth factor (NGF), in the hippocampus and/or cortex of mice, and the levels of glutamate and GABA were normalized after PTZ-induced kindling by (R)-32. Importantly, besides antiseizure activity, (R)-32 demonstrated potent antinociceptive efficacy in formalin-induced pain, capsaicin-induced pain, as well as oxaliplatin- and streptozotocin-induced peripheral neuropathy in mice (i.p.). No influence on muscular strength and body temperature in mice was observed. Pharmacokinetic studies and in vitro ADME-Tox data (i.e., high metabolic stability in human liver microsomes, a weak influence on CYPs, no hepatotoxicity, satisfactory passive transport, etc.) proved favorable drug-like properties of (R)-32. Thermal stability of (R)-32 shown in thermogravimetry and differential scanning calorimetry gives the opportunity to develop innovative oral solid dosage forms loaded with this compound. The in vitro binding and functional assays indicated its multimodal mechanism of action. (R)-32, beyond TRPV1 antagonism, inhibited calcium and sodium currents at a concentration of 10 μM. Therefore, the data obtained in the current studies justify a more detailed preclinical development of (R)-32 for epilepsy and pain indications.

Perspectives on Stem Cell Therapy in Diabetic Neuropathic Pain

Diabetes mellitus-related morbidity and mortality are primarily caused by long-term complications such as retinopathy, nephropathy, cardiomyopathy, and neuropathy. Diabetic neuropathy (DN) involves the progressive degeneration of axons and nerve fibers due to chronic exposure to hyperglycemia. This metabolic disturbance leads to excessive activation of the glycolytic pathway, inducing oxidative stress and mitochondrial dysfunction, ultimately resulting in nerve damage. There is no specific treatment for painful DN, and new approaches should aim not only to relieve pain but also to prevent oxidative stress and reduce inflammation. Given that existing therapies for painful DN are not effective for diabetic patients, mesenchymal stromal cells (MSCs)-based therapy shows promise for providing immunomodulatory and paracrine regulatory functions. MSCs from various sources can improve neuronal dysfunction associated with DN. Transplantation of MSCs has led to a reduction in hyperalgesia and allodynia, along with the recovery of nerve function in diabetic rats. While the pathogenesis of diabetic neuropathic pain is complex, clinical trials have demonstrated the importance of MSCs in modulating the immune response in diabetic patients. MSCs reduce the levels of inflammatory factors and increase anti-inflammatory cytokines, thereby interfering with the progression of DM. Further investigation is necessary to ensure the safety and efficacy of MSCs in preventing or treating neuropathic pain in diabetic patients.

Comparison of the Effects of Combined Femoral and Sciatic Nerves Block versus General Anesthesia on Hemodynamic Stability and Postoperative Complication in Patients with Diabetic Foot: A Prospective, Double-Blind and Randomized Controlled Trial

Background

Perioperative anesthetic management of patients with diabetic foot undergoing surgical treatment is challenging due to their poor cardiovascular health status. According to previous literature, general anesthesia and peripheral nerve block have their own advantages and disadvantages for such patients. We reported the effect of these two anesthesia techniques on perioperative hemodynamics and prognosis in these patients.

Methods

This study employed a prospective randomized controlled design, where patients meeting the inclusion criteria were assigned to two groups: the general anesthesia group (GA group) and the peripheral nerve block group (PNB group). The primary outcomes were the differences in intraoperative hemodynamic stability and the incidence of postoperative complications between the two groups. The second outcomes were postoperative numerical rating scale scores, analgesic drug remedies, postoperative sleep conditions monitored by sleep bracelets and health status assessed by EQ-5D-5 L scores.

Results

One hundred and nine subjects were enrolled in this study, including 54 in the GA group and 55 in the PNB group. The baseline parameters of the two groups were comparable. The GA group exhibited a significantly higher incidence of hypotension, and Colloid intake and total fluid intake were significantly higher in the GA group than in the PNB group. Additionally, a larger proportion of patients in the GA group. The scores of postoperative pain during the 48 hours after surgery were significantly higher, and more patients needed tramadol for postoperative analgesia during the 24 h after surgery in the GA group than in the PNB group. Patients in the PNB group slept better, first feeding time, earlier out-of-bed activity and earlier discharge from the hospital, compared to the GA group. However, there was no obvious difference in postoperative complications between the two groups except pharyngeal pain.

Conclusion

Peripheral nerve block is a better option in patients with diabetes undergoing elective below-knee surgery than general anesthesia.

Novel Alaninamide Derivatives with Drug-like Potential for Development as Antiseizure and Antinociceptive Therapies─In Vitro and In Vivo Characterization

In the present study, a series of original alaninamide derivatives have been designed applying a combinatorial chemistry approach, synthesized, and characterized in the in vivo and in vitro assays. The obtained molecules showed potent and broad-spectrum activity in basic seizure models, namely, the maximal electroshock (MES) test, the 6 Hz (32 mA) seizure model, and notably, the 6 Hz (44 mA) model of pharmacoresistant seizures. Most potent compounds 26 and 28 displayed the following pharmacological values: ED50 = 64.3 mg/kg (MES), ED50 = 15.6 mg/kg (6 Hz, 32 mA), ED50 = 29.9 mg/kg (6 Hz, 44 mA), and ED50 = 34.9 mg/kg (MES), ED50 = 12.1 mg/kg (6 Hz, 32 mA), ED50 = 29.5 mg/kg (6 Hz, 44 mA), respectively. Additionally, 26 and 28 were effective in the ivPTZ seizure threshold test and had no influence on the grip strength. Moreover, lead compound 28 was tested in the PTZ-induced kindling model, and then, its influence on glutamate and GABA levels in the hippocampus and cortex was evaluated by the high-performance liquid chromatography (HPLC) method. In addition, 28 revealed potent efficacy in formalin-induced tonic pain, capsaicin-induced pain, and oxaliplatin- and streptozotocin-induced peripheral neuropathy. Pharmacokinetic studies and in vitro ADME-Tox data proved favorable drug-like properties of 28. The patch-clamp recordings in rat cortical neurons showed that 28 at a concentration of 10 μM significantly inhibited fast sodium currents. Therefore, 28 seems to be an interesting candidate for future preclinical development in epilepsy and pain indications.

Diabetic Neuropathy: Pathophysiology Review

PURPOSE OF REVIEW

Diabetic neuropathy is a debilitating complication of diabetes mellitus that affects millions of individuals worldwide. It is characterized by nerve damage resulting from prolonged exposure to high blood glucose levels. Diabetic neuropathy may cause a range of symptoms, including pain, numbness, muscle weakness, autonomic dysfunction, and foot ulcers, potentially causing significant impairment to the quality of life for those affected. This review article aims to provide a comprehensive overview of the pathophysiology of diabetic neuropathy. The etiology of diabetic neuropathy will be discussed, including risk factors, predisposing conditions, and an overview of the complex interplay between hyperglycemia, metabolic dysregulation, and nerve damage. Additionally, we will explore the molecular mechanisms and pathways of diabetic neuropathy, including the impact of hyperglycemia on nerve function, abnormalities in glucose metabolism, the role of advanced glycation end products (AGEs), and inflammatory and immune-mediated processes. We will provide an overview of the various nerve fibers affected by diabetic neuropathy and explore the common symptoms and complications associated with diabetic neuropathy in the pain medicine field.

RECENT FINDINGS

This review highlights advances in understanding the pathophysiology of diabetic neuropathy as well as reviews potential novel therapeutic strategies and promising areas for future research. In conclusion, this review article aims to shed light on the pathophysiology of diabetic neuropathy, its far-reaching consequences, and the evolving strategies for prevention and management. In understanding the mechanisms of diabetic neuropathy and the ongoing research in this area, healthcare professionals can better serve patients with diabetes, ultimately improving well-being and reducing complications.

Serum brain-derived neurotrophic factor levels in type 2 diabetes mellitus patients and its association with cognitive impairment: A meta-analysis

OBJECTIVE

To compare the serum levels of brain-derived neurotrophic factor (BDNF) in type 2 diabetes mellitus (T2DM) patients with healthy controls (HC) and evaluate the BDNF levels in T2DM patients with/without cognitive impairment.

METHODS

PubMed, EMBASE, and the Cochrane Library databases were searched for the published English literature on BDNF in T2DM patients from inception to December 2022. The BDNF data in the T2DM and HC groups were extracted, and the study quality was evaluated using the Agency for Healthcare Research and Quality. A meta-analysis of the pooled data was conducted using Review Manager 5.3 and Stata 12.0 software.

RESULTS

A total of 18 English articles fulfilled with inclusion criteria. The standard mean difference of the serum BDNF level was significantly lower in T2DM than that in the HC group (SMD: -2.04, z = 11.19, P <0.001). Besides, T2DM cognitive impairment group had a slightly lower serum BDNF level compared to the non-cognitive impairment group (SMD: -2.59, z = 1.87, P = 0.06).

CONCLUSION

BDNF might be involved in the neuropathophysiology of cerebral damage in T2DM, especially cognitive impairment in T2DM.

Comparison of therapeutic effects of N-Acetylcysteine with pregabalin in improving the clinical symptoms of painful diabetic neuropathy: a randomized, double-blind clinical trial

OBJECTIVES

Painful diabetic neuropathy (PDN) is highly prevalent and annoyingly in patients with diabetes. The aim of this study was to investigate the effects of oral N-acetylcysteine (NAC) compared to pregabalin in PDN.

METHODS

One hundred two eligible patients with type 2 diabetes and PDN were randomly recievied pregabalin (150 mg/day) or N-Acetylcysteine (NAC) (600 mg/ twice a day) for 8 weeks. Mean pain score, Sleep interference score (SIS), Patient Global Impression of Change (PGIC), Clinical Global Impression of Change (CGIC), and also, serum levels of total antioxidant capacity (TAC), total thiol groups (TTG), catalase activity (CAT), nitric oxide (NO), and malondialdehyde (MDA) were assessed at baseline and at the end of the study.

RESULTS

NAC was well tolerated in all patients. The decrease in mean pain scores and increase in SIS was similar between two groups. More improvement in PGIC and CGIC from the baseline was reported in NAC group. NAC, significantly, decreased serum levels of MDA, and NO, but increased TAC, TTG, and CAT. Pregabalin, significantly, decreased serum levels of MDA, and NO and increased TAC.

DISCUSSION

NAC is efficacious in alleviate symptoms of PDN which is probably related to its antioxidant effects.

TRIAL REGISTRATION

The research protocol received approval from the Ethics Committee of Hamadan University of Medical Sciences (IR.UMSHA.REC.1397.137). The trial registry URL and number in Iranian Registry of Clinical Trials (IRCT): https://www.irct.ir/trial/33313 , IRCT20180814040795N2 (Registration date: 2019-01-21, Retrospectively registered).

Painful diabetic neuropathy: The role of ion channels

Painful diabetic neuropathy (PDN) is a common chronic complication of diabetes that causes neuropathic pain and negatively affects the quality of life. The management of PDN is far from satisfactory. At present, interventions are primarily focused on symptomatic treatment. Ion channel disorders are a major cause of PDN, and a complete understanding of their roles and mechanisms may provide better options for the clinical treatment of PDN. Therefore, this review summarizes the important role of ion channels in PDN and the current drug development targeting these ion channels.

Single-cell analysis of age-related changes in leukocytes of diabetic mouse hindpaws

Complications associated with Type 1 and Type 2 diabetes, such as diabetic peripheral neuropathy and diabetic foot ulcers, are a growing health-care concern. In addition, this concern increases as diabetic patients age due to their increased susceptibility to complications. To address this growing problem, it is important to understand fluctuations in physiology which lead to pathological changes associated with the metabolic disturbances of diabetes. Our study explores dysregulation of immune cell populations in the hindpaws of healthy and diabetic mice at 12 and 21 weeks of age using single-cell RNA sequencing to provide insight into immune disruptions occurring in the distal limb during chronic diabetes. In 21-week-old Leprdb/db mice, increases were seen in mast cells/basophils, dermal γδ T cells, heterogeneous T cells, and Type 2 innate lymphoid cells. In addition, macrophages represented the largest cluster of immune cells and showed the greatest increase in genes associated with immune-specific pathways. Sub-clustering of macrophages revealed a bias toward angiogenic Lyve1+MHCIIlo macrophages in the hindpaws of 21-week-old diabetic mice, which corresponded to an increase in Lyve1+ macrophages in the hindpaws of 21-week-old diabetic mice on histology. Our results show that in Type 2 diabetes, the immunological function and phenotype of multiple immune cell types shift not only with metabolic disturbance, but also with duration of disease, which may explain the increased susceptibility to pathologies of the distal limb in patients with more chronic diabetes.

Update on Treating Painful Diabetic Peripheral Neuropathy: A Review of Current US Guidelines with a Focus on the Most Recently Approved Management Options

Painful diabetic peripheral neuropathy (DPN) is a highly prevalent and disabling complication of diabetes that is often misdiagnosed and undertreated. The management of painful DPN involves treating its underlying cause via lifestyle modifications and intensive glucose control, targeting its pathogenesis, and providing symptomatic pain relief, thereby improving patient function and health-related quality of life. Four pharmacologic options are currently approved by the US Food and Drug Administration (FDA) to treat painful DPN. These include three oral medications (duloxetine, pregabalin, and tapentadol extended release) and one topical agent (capsaicin 8% topical system). More recently, the FDA approved several spinal cord stimulation (SCS) devices to treat refractory painful DPN. Although not FDA-approved specifically to treat painful DPN, tricyclic antidepressants, serotonin/norepinephrine reuptake inhibitors, gabapentinoids, and sodium channel blockers are common first-line oral options in clinical practice. Other strategies may be used as part of individualized comprehensive pain management plans. This article provides an overview of the most recent US guidelines for managing painful DPN, with a focus on the two most recently approved treatment options (SCS and capsaicin 8% topical system), as well as evidence for using FDA-approved and guideline-supported drugs and devices. Also discussed are unmet needs for this patient population, and evidence for potential future treatments for painful DPN, including drugs with novel mechanisms of action, electrical stimulation devices, and nutraceuticals.

Impact of Resveratrol and Pharmaceutical Care on Type 2 Diabetes Mellitus and Its Neuropathic Complication: A Randomized Placebo Controlled Clinical Trial

Background. Management of diabetic neuropathy (DN) is a challenging issue. Therefore, integration of pharmaceutical care provided by the clinical pharmacists with pharmacotherapy may provide multifaceted approach to target the management of hyperglycemia and diabetic neuropathic complication. This study aimed to evaluate the effects of resveratrol (Resv) and/or pharmaceutical care (PC) on glycemic control and amelioration of diabetes-associated neuropathic complications. Patients and Methods. A four-arm randomized placebo-controlled clinical trial assigned 120 patients from the Diabetes and Endocrinology Center in Sulaymaniyah City, Iraq. The patients were divided into four groups. The Resv group (n = 30) received 500 mg Resv capsules once daily. The Placebo group (n = 30) received placebo capsules. Resv + PC (n = 30) received Resv 500 mg capsules with PC. Placebo + PC (n = 30) received placebo capsule plus PC. The duration of the intervention was 90 days. Drug therapy problems (DTPs) have been utilized as an important domain in PC. Clinical signs, symptoms, and neuropathic abnormalities were assessed using the Michigan Neuropathy Screening Instrument (MNSI), Douleur Neuropathique 4 (DN4) questions, and nerve conduction studies (NCSs) of the lower-limb sensory and motor nerves. Results. 97 patients from all the groups completed the study. At baseline, 84% of the Resv, 87% of the Placebo, and 92% of each of Resv + PC and Placebo + PC groups, respectively, had at least one DTP. The provision of PC resulted in a dramatic reduction in the number of DTP. Resveratrol with PC significantly ameliorated hyperglycemic status, neuropathic signs, and symptoms, as evidenced by a decrease in MNSI and DN4 scores and improvement in electroneurographic parameters. Conclusion. These findings support the integration of the PC concept into a pharmacotherapy intervention; they also encourage supplementation of Resv with conventional diabetes therapy to emphasize on the importance of this herbal medicine with the provision of PC in the management of diabetes and its neuropathic complications. This trial is registered with NCT05172947.

4. Painful diabetic polyneuropathy

INTRODUCTION

Pain as a symptom of diabetic polyneuropathy (DPN) significantly lowers quality of life, increases mortality and is the main reason for patients with diabetes to seek medical attention. The number of people suffering from painful diabetic polyneuropathy (PDPN) has increased significantly over the past decades.

METHODS

The literature on the diagnosis and treatment of diabetic polyneuropathy was retrieved and summarized.

RESULTS

The etiology of PDPN is complex, with primary damage to peripheral nociceptors and altered spinal and supra-spinal modulation. To achieve better patient outcomes, the mode of diagnosis and treatment of PDPN evolves toward more precise pain-phenotyping and genotyping based on patient-specific characteristics, new diagnostic tools, and prior response to pharmacological treatments. According to the Toronto Diabetic Neuropathy Expert Group, a presumptive diagnosis of "probable PDPN" is sufficient to initiate treatment. Proper control of plasma glucose levels, and prevention of risk factors are essential in the treatment of PDPN. Mechanism-based pharmacological treatment should be initiated as early as possible. If symptomatic pharmacologic treatment fails, spinal cord stimulation (SCS) should be considered. In isolated cases, where symptomatic pharmacologic treatment and SCS are unsuccessful or cannot be used, sympathetic lumbar chain neurolysis and/or radiofrequency ablation (SLCN/SLCRF), dorsal root ganglion stimulation (DRGs) or posterior tibial nerve stimulation (PTNS) may be considered. However, it is recommended that these treatments be applied only in a study setting in a center of expertise.

CONCLUSIONS

The diagnosis of PDPN evolves toward pheno-and genotyping and treatment should be mechanism-based.

Diabetic peripheral neuropathy: pathogenetic mechanisms and treatment

Diabetic peripheral neuropathy (DPN) refers to the development of peripheral nerve dysfunction in patients with diabetes when other causes are excluded. Diabetic distal symmetric polyneuropathy (DSPN) is the most representative form of DPN. As one of the most common complications of diabetes, its prevalence increases with the duration of diabetes. 10-15% of newly diagnosed T2DM patients have DSPN, and the prevalence can exceed 50% in patients with diabetes for more than 10 years. Bilateral limb pain, numbness, and paresthesia are the most common clinical manifestations in patients with DPN, and in severe cases, foot ulcers can occur, even leading to amputation. The etiology and pathogenesis of diabetic neuropathy are not yet completely clarified, but hyperglycemia, disorders of lipid metabolism, and abnormalities in insulin signaling pathways are currently considered to be the initiating factors for a range of pathophysiological changes in DPN. In the presence of abnormal metabolic factors, the normal structure and function of the entire peripheral nervous system are disrupted, including myelinated and unmyelinated nerve axons, perikaryon, neurovascular, and glial cells. In addition, abnormalities in the insulin signaling pathway will inhibit neural axon repair and promote apoptosis of damaged cells. Here, we will discuss recent advances in the study of DPN mechanisms, including oxidative stress pathways, mechanisms of microvascular damage, mechanisms of damage to insulin receptor signaling pathways, and other potential mechanisms associated with neuroinflammation, mitochondrial dysfunction, and cellular oxidative damage. Identifying the contributions from each pathway to neuropathy and the associations between them may help us to further explore more targeted screening and treatment interventions.

Serum levels of endocannabinoids and related lipids in painful vs painless diabetic neuropathy: results from the Pain in Neuropathy Study

ABSTRACT

N-arachidonoylethanolamine (also known as anandamide) and 2-arachidonoylglycerol are activators of the cannabinoid receptors. The endocannabinoid system also includes structurally and functionally related lipid mediators that do not target cannabinoid receptors, such as oleoylethanolamide, palmitoylethanolamide, and stearoylethanolamide. These bioactive lipids are involved in various physiological processes, including regulation of pain. The primary aim of the study was to analyze associations between serum levels of these lipids and pain in participants in the Pain in Neuropathy Study, an observational, cross-sectional, multicentre, research project in which diabetic patients with painless or painful neuropathy underwent deep phenotyping. Our hypothesis was that painful neuropathy would be associated with higher levels of the 5 lipids compared with painless neuropathy. Secondary aims were to analyze other patient-reported outcome measures and clinical data in relationship to lipid levels. The lipid mediators were analyzed in serum samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). Serum levels of anandamide were significantly higher in the painful group, but the effect size was small (Cohen d = 0.31). Using cluster analysis of lipid data, patients were dichotomized into a "high-level" endocannabinoid group and a "low-level" group. In the high-level group, 61% of patients had painful neuropathy, compared with 45% in the low-level group ( P = 0.039). This work is of a correlative nature only, and the relevance of these findings to the search for analgesics targeting the endocannabinoid system needs to be determined in future studies.

[The intensity of neuropathic pain and the severity of insomnia in diabetic polyneuropathy]

OBJECTIVE

To determine the prevalence of insomnia and the effectiveness of its treatment in patients with a painful form of diabetic polyneuropathy (DPN).

MATERIAL AND METHODS

Fifty patients with the painful form of DPN were randomly divided into 2 groups: the standard therapy group (ST) and the extended therapy group (ET). In the ST group, a single lesson on sleep hygiene was conducted, in the ET group there were 3-4 face-to-face individual sessions for the treatment of insomnia for two weeks. Both groups were interviewed at the time of hospitalization, after 3 and 6 months. The severity of polyneuropathy and the nature of neuropathic pain were assessed using the Neuropathic Neuropathy Impairment Score in the Lower Limbs (NIS-LL) and the Neuropathy Total Symptom Score - 9 (NTSS-9); the intensity of pain was assessed using a Visual Analog Scale (VAS). Sleep disorders were analyzed using the Pittsburgh Sleep Quality Index (PSQI) and the Insomnia Severity Index (ISI).

RESULTS

Sleep disorders of varying severity were observed in 82% of patients in the initial survey. In both groups, improvement in sleep quality was noted during treatment, but significantly better results were in the ET group, the ISI score after 6 months was 7.15±2.08 for the ST group and 3.07±2.49 for the ET group (p<0.0001). In the ST group, there was no significant decrease in the intensity of pain and the severity of polyneuropathy in dynamics. In the ET group, a significant decrease in NTSS-9 and VAS scores was found during the initial survey and after 6 months (p<0.0001). The intensity of pain also significantly decreased in the ET group compared with the ST group (p<0.0001) at the end of follow-up, which indicates the importance of sleep normalization in the treatment of neuropathic pain.

CONCLUSION

Most patients with the painful form of DPN have insomnia. Treatment of insomnia has shown its effectiveness as part of a multimodal approach to the managing of neuropathic pain in DPN and improving the quality of life of patients.

Painful Diabetic Neuropathy: The Need for New Approaches

Painful diabetic neuropathy is a common vexing problem for people with diabetes and a costly problem for society. The pathophysiology is not well understood, and no safe and effective mechanistically-based treatment has been identified. Poor glycemic control is a risk factor for painful diabetic neuropathy. Excessive intraneuronal glucose in people with diabetes can be shunted away from physiological glycolysis into multiple pathological pathways associated with neuropathy and pain. The first three treatments that are traditionally offered consist of risk factor reduction, lifestyle modifications, and pharmacological therapy, which includes only three drugs that are approved for this indication by the United States Food and Drug Administration. All of these traditional treatments are often inadequate for relieving neuropathic pain, and thus, new approaches are needed. Modern devices based on neuromodulation technology, which act directly on the nervous system, have been recently cleared by the United States Food and Drug Administration for painful diabetic neuropathy and offer promise as next-in-line therapy when traditional therapies fail.

Female sex is a risk factor for painful diabetic peripheral neuropathy: the EURODIAB prospective diabetes complications study

AIMS/HYPOTHESIS

While the risk factors for diabetic peripheral neuropathy (DPN) are now well recognised, the risk factors for painful DPN remain unknown. We performed analysis of the EURODIAB Prospective Complications Study data to elucidate the incidence and risk factors of painful DPN.

METHODS

The EURODIAB Prospective Complications Study recruited 3250 participants with type 1 diabetes who were followed up for 7.3±0.6 (mean ± SD) years. To evaluate DPN, a standardised protocol was used, including clinical assessment, quantitative sensory testing and autonomic function tests. Painful DPN (defined as painful neuropathic symptoms in the legs in participants with confirmed DPN) was assessed at baseline and follow-up.

RESULTS

At baseline, 234 (25.2%) out of 927 participants with DPN had painful DPN. At follow-up, incident DPN developed in 276 (23.5%) of 1172 participants. Of these, 41 (14.9%) had incident painful DPN. Most of the participants who developed incident painful DPN were female (73% vs 48% painless DPN p=0.003) and this remained significant after adjustment for duration of diabetes and HbA1c (OR 2.69 [95% CI 1.41, 6.23], p=0.004). The proportion of participants with macro- or microalbuminuria was lower in those with painful DPN compared with painless DPN (15% vs 34%, p=0.02), and this association remained after adjusting for HbA1c, diabetes duration and sex (p=0.03).

CONCLUSIONS/INTERPRETATION

In this first prospective study to investigate the risk factors for painful DPN, we definitively demonstrate that female sex is a risk factor for painful DPN. Additionally, there is less evidence of diabetic nephropathy in incident painful, compared with painless, DPN. Thus, painful DPN is not driven by cardiometabolic factors traditionally associated with microvascular disease. Sex differences may therefore play an important role in the pathophysiology of neuropathic pain in diabetes. Future studies need to look at psychosocial, genetic and other factors in the development of painful DPN.

Medicinal Plants for the Treatment of Neuropathic Pain: A Review of Randomized Controlled Trials

Neuropathic pain is a disabling condition caused by various diseases and can profoundly impact the quality of life. Unfortunately, current treatments often do not produce complete amelioration and can be associated with potential side effects. Recently, herbal drugs have garnered more attention as an alternative or a complementary treatment. In this article, we summarized the results of randomized clinical trials to evaluate the effects of various phytomedicines on neuropathic pain. In addition, we discussed their main bioactive components and potential mechanisms of action to provide a better view of the application of herbal drugs for treating neuropathic pain.

Arginine Biosynthesis Pathway Found to Play a Key Role in the Neuroprotective Effect of Liu-Wei-Luo-Bi (LWLB) Granules in Diabetic db/db Mice with Peripheral Neuropathy Using an Untargeted Metabolomics Strategy

Aim

Liu-Wei-Luo-Bi (LWLB) granules was a Chinese compound prescription for treating diabetic peripheral neuropathy (DPN). The aim of this study was to investigate the effect of LWLB granules on diabetic mice with peripheral neuropathy and to elucidate the potential mechanism based on an untargeted metabolomics approach.

Methods

One hundred forty db/db mice were randomly divided into seven groups: the Control group, DPN group, Mudan (MD) granules group, Epalrestat (Epa) group, and the LWLB low, medium, or high dose (LW-l, LW-m, or LW-h) group. After 12 weeks of treatment, body weight, blood glucose, mechanical pain threshold, motor conduction velocity (MCV), sensory conduction velocity (SCV), and Pathological Organization of the Sciatic and Caudal Nerves in mice were measured. Serum samples were collected for untargeted metabolomics analysis using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and multivariate statistics. Disease-related pathways were screened out with function enrichment analyses of candidate biomarkers.

Results

LWLB granules can improve the peripheral neuropathy of type 2 diabetic mice with peripheral nerve conduction disorders, mainly through significantly improving the nerve conduction velocity (P < 0.05) and lowering the mechanical pain threshold (P < 0.05). A total of 43 metabolites were identified as potential biomarkers related to the therapeutic effect of LWLB granules. Fifty, 4, and 26; 23, 4, and 22; and 24, 1, and 16 biomarkers were discovered in the LW-l, LW-m, and LW-h groups at the 4th, 6th, and 12th weeks, respectively. Five, three, seven, five, and four metabolic pathways were found in MD, Epa, LW-l, LW-m, and LW-h groups, respectively. The arginine biosynthesis pathway is the overlapping pathway in LW-l, LW-m, and LW-h groups.

Conclusion

LWLB granules have an obvious neuroprotective effect on diabetic peripheral neuropathy, and the metabolism mechanism of LWLB is mainly related to the arginine biosynthesis pathway on diabetic db/db mice with peripheral neuropathy.

Dietary and Nutritional Supplementation for Painful Diabetic Neuropathy: A Narrative Review

Painful diabetic neuropathy (PDN) is a serious and very common complication of diabetes mellitus (DM). It negatively affects the quality of life, increases morbidity and poses a financial burden on the health care system. Currently, treatment of PDN focuses on glycaemic control, while pathogenesis-oriented therapy has not yielded satisfactory results. The need to improve therapy remains. There is accumulating evidence on the potential benefit of nutritional interventions. This narrative review aims to examine the potential benefit of dietary and nutritional supplementation for PDN management. According to the preliminary research, supplementation with vitamin E, B-complex, omega-3 fatty acids, CoQ10 or N-acetylcysteine seems to be associated with promising results in improving PDN symptoms.

Effect of Hesperidin on Sciatic Nerve Damage in STZ-Induced Diabetic Neuropathy: Modulation of TRPM2 Channel

Diabetic neuropathy (DNP) is a severe complication of diabetes mellitus. In this study, we examined the potential of hesperidin (HES) to attenuate DNP and the involvement of the TRPM2 channel in this process. The rats were given a single dose of 45 mg/kg of streptozotocin (STZ) intraperitoneally to induce diabetic neuropathic pain. On the third day, we confirmed the development of diabetes in the DNP and DNP + HES groups. The HES groups were treated with 100 mg/kg and intragastric gavage daily for 14 days. The results showed that treatment with HES in diabetic rats decreased STZ-induced hyperglycemia and thermal hyperalgesia. Furthermore, in the histopathological examination of the sciatic nerve, HES treatment reduced STZ-induced damage. The immunohistochemical analysis also determined that STZ-induced increased TRPM2 channel, type-4 collagen, and fibrinogen immunoactivity decreased with HES treatment. In addition, we investigated the TRPM2 channel activation in the sciatic nerve damage mechanism of DNP model rats created by STZ application using the ELISA method. We determined the regulatory effect of HES on increased ROS, and PARP1 and TRPM2 channel activation in the sciatic nerves of DNP model rats. These findings indicated that hesperidin treatment could attenuate diabetes-induced DNP by reducing TRPM2 channel activation.

Vascular complications of diabetes: A narrative review

Diabetes mellitus is a complex chronic metabolic disease characterized by hyperglycemia and various complications. According to the different pathophysiological mechanisms, these complications can be classified as microvascular or macrovascular complications, which have long-term negative effects on vital organs such as the eyes, kidneys, heart, and brain, and lead to increased patient mortality. Diabetes mellitus is a major global health issue, and its incidence and prevalence have increased significantly in recent years. Moreover, the incidence is expected to continue to rise as more people adopt a Western lifestyle and diet. Thus, it is essential to understand the epidemiology, pathogenesis, risk factors, and treatment of vascular complications to aid patients in managing the disease effectively. This paper provides a comprehensive review of the literature to clarify the above content. Furthermore, this paper also delves into the correlation between novel risk factors, such as long noncoding RNAs, gut microbiota, and nonalcoholic fatty liver disease, with diabetic vascular complications.

Painful diabetic peripheral neuropathy of the feet: integrating prescription-strength capsaicin into office procedures

Prescription-strength (8%) capsaicin topical system is a US FDA-approved treatment for painful diabetic peripheral neuropathy of the feet. A 30 min application of the capsaicin 8% topical system can provide sustained (up to 3 months) local pain relief by desensitizing and reducing TRPV1-expressing cutaneous fibers. Capsaicin is not absorbed systemically; despite associated application-site discomfort, capsaicin 8% topical system is well tolerated, with no known drug interactions or contraindications, and could offer clinical advantages over oral options. Capsaicin 8% topical system are not for patient self-administration and require incorporation into office procedures, with the added benefit of treatment compliance. This article reviews existing literature and provides comprehensive, practical information regarding the integration of capsaicin 8% topical systems into office procedures.

Understanding the role of hyperglycemia and the molecular mechanism associated with diabetic neuropathy and possible therapeutic strategies

Diabetic neuropathy is a neuro-degenerative disorder that encompasses numerous factors that impact peripheral nerves in the context of diabetes mellitus (DM). Diabetic peripheral neuropathy (DPN) is very prevalent and impacts 50% of diabetic patients. DPN is a length-dependent peripheral nerve lesion that primarily causes distal sensory loss, discomfort, and foot ulceration that may lead to amputation. The pathophysiology is yet to be fully understood, but current literature on the pathophysiology of DPN revolves around understanding various signaling cascades involving the polyol, hexosamine, protein-kinase C, AGE, oxidative stress, and poly (ADP ribose) polymerase pathways. The results of research have suggested that hyperglycemia target Schwann cells and in severe cases, demyelination resulting in central and peripheral sensitization is evident in diabetic patients. Various diagnostic approaches are available, but detection at an early stage remains a challenge. Traditional analgesics and opioids that can be used "as required" have not been the mainstay of treatment thus far. Instead, anticonvulsants and antidepressants that must be taken routinely over time have been the most common treatments. For now, prolonging life and preserving the quality of life are the ultimate goals of diabetes treatment. Furthermore, the rising prevalence of DPN has substantial consequences for occupational therapy because such therapy is necessary for supporting wellness, warding off other chronic-diseases, and avoiding the development of a disability; this is accomplished by engaging in fulfilling activities like yoga, meditation, and physical exercise. Therefore, occupational therapy, along with palliative therapy, may prove to be crucial in halting the onset of neuropathic-symptoms and in lessening those symptoms once they have occurred.

Netrin-3 Suppresses Diabetic Neuropathic Pain by Gating the Intra-epidermal Sprouting of Sensory Axons

Diabetic neuropathic pain (DNP) is the most common disabling complication of diabetes. Emerging evidence has linked the pathogenesis of DNP to the aberrant sprouting of sensory axons into the epidermal area; however, the underlying molecular events remain poorly understood. Here we found that an axon guidance molecule, Netrin-3 (Ntn-3), was expressed in the sensory neurons of mouse dorsal root ganglia (DRGs), and downregulation of Ntn-3 expression was highly correlated with the severity of DNP in a diabetic mouse model. Genetic ablation of Ntn-3 increased the intra-epidermal sprouting of sensory axons and worsened the DNP in diabetic mice. In contrast, the elevation of Ntn-3 levels in DRGs significantly inhibited the intra-epidermal axon sprouting and alleviated DNP in diabetic mice. In conclusion, our studies identified Ntn-3 as an important regulator of DNP pathogenesis by gating the aberrant sprouting of sensory axons, indicating that Ntn-3 is a potential druggable target for DNP treatment.

Biomarkers in diabetic neuropathy

CONTEXT

The prevalence of diabetic neuropathy is drastically increasing in the world. To halt the progression of diabetic neuropathy, there is an unmet need to have potential biomarkers for the diagnosis and new drug discovery.

OBJECTIVE

To study various biomarkers involved in the pathogenesis of diabetic neuropathy.

METHODS

The literature was searched with the help of various scientific databases and resources like PubMed, ProQuest, Scopus, and Google scholar from the year 1976 to 2020.

RESULTS

Biomarkers of diabetic neuropathy are categorised as inflammatory biomarkers such as MCP-1, VEGF, TRPV1, NF-κB; oxidative biomarkers such as adiponectin, NFE2L2; enzyme biomarkers like NADPH, ceruloplasmin, HO-1, DPP-4, PARP α; miscellaneous biomarkers such as SIRT1, caveolin 1, MALAT1, and microRNA. All biomarkers have a significant role in the pathogenesis of diabetic neuropathy.

CONCLUSION

These biomarkers have a potential role in the progression of diabetic neuropathy and can be considered as potential targets for new drug discovery.

Preservation of thalamic neuronal function may be a prerequisite for pain perception in diabetic neuropathy: A magnetic resonance spectroscopy study

Introduction

In this study, we used proton Magnetic Resonance Spectroscopy (1H-MRS) to determine the neuronal function in the thalamus and primary somatosensory (S1) cortex in different subgroups of DPN, including subclinical- and painful-DPN.

Method

One-hundred and ten people with type 1 diabetes [20 without DPN (no-DPN); 30 with subclinical-DPN; 30 with painful-DPN; and 30 with painless-DPN] and 20 healthy volunteers, all of whom were right-handed men, were recruited and underwent detailed clinical and neurophysiological assessments. Participants underwent Magnetic Resonance Imaging at 1.5 Tesla with two 1H-MRS spectra obtained from 8 ml cubic volume voxels: one placed within left thalamus to encompass the ventro-posterior lateral sub-nucleus and another within the S1 cortex.

Results

In the thalamus, participants with painless-DPN had a significantly lower NAA:Cr ratio [1.55 + 0.22 (mean ± SD)] compared to all other groups [HV (1.80 ± 0.23), no-DPN (1.85 ± 0.20), sub-clinical DPN (1.79 ± 0.23), painful-DPN (1.75 ± 0.19), ANOVA p < 0.001]. There were no significant group differences in S1 cortical neurometabolites.

Conclusion

In this largest cerebral MRS study in DPN, thalamic neuronal dysfunction was found in advanced painless-DPN with preservation of function in subclinical- and painful-DPN. Furthermore, there was a preservation of neuronal function within the S1 cortex in all subgroups of DPN. Therefore, there may be a proximo-distal gradient to central nervous system alterations in painless-DPN, with thalamic neuronal dysfunction occurring only in established DPN. Moreover, these results further highlight the manifestation of cerebral alterations between painful- and painless-DPN whereby preservation of thalamic function may be a prerequisite for neuropathic pain in DPN.

Lysine demethylase KDM5B down-regulates SIRT3-mediated mitochondrial glucose and lipid metabolism in diabetic neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common neurological complication of diabetes mellitus without efficient interventions. Both lysine demethylase 5B (KDM5B) and sirtuin-3 (SIRT3) have been found to regulate islet function and glucose homeostasis. KDM5B was predicted to bind to the SIRT3 promoter by bioinformatics. Here, we investigated whether KDM5B affected DPN development via modulating SIRT3.

METHODS

The db/db mice and high glucose-stimulated Schwann cells (RSC96) were used as in vivo and in vitro models of DPN, respectively. Glucose level, glucose and insulin tolerance of mice were measured. Neurological function was evaluated by motor nerve conduction velocity (MNCV), tactile allodynia assay and thermal sensitivity assay. Adenosine triphosphate level, oxygen consumption rate, extracellular acidification rate, β-oxidation rate, acetyl-CoA level, acetylation levels and activities of long-chain acyl CoA dehydrogenase (LCAD) and pyruvate dehydrogenase (PDH) were detected. Methyl thiazolyl tetrazolium assay was adopted to determine cell viability. Reactive oxygen species (ROS) production was detected by MitoSox staining. Western blotting for measuring target protein levels. Molecular mechanisms were investigated by co-immunoprecipitine (Co-IP), chromatin immunoprecipitation (ChIP) and luciferase reporter assay.

RESULTS

KDM5B was up-regulated, while SIRT3 was down-regulated in DPN models. SIRT3 overexpression or AMPK activation ameliorated mitochondrial metabolism dysfunction and ROS overproduction during DPN. KDM5B overexpression triggered mitochondrial metabolism disorder and oxidative stress via directly transcriptional inhibiting SIRT3 expression by demethylating H3K4me3 or indirectly repressing AMPK pathway-regulated SIRT3 expression.

CONCLUSION

KDM5B contributes to DPN via regulating SIRT3-mediated mitochondrial glucose and lipid metabolism. KDM5B inhibition may be an effective intervention for DPN.

Nutraceuticals: A Promising Approach Towards Diabetic Neuropathy

BACKGROUND

Various nutraceuticals from different sources have various beneficial actions and have been reported for many years. The important findings from the research conducted using various nutraceuticals exhibiting significant physiological and pharmacological activities have been summarized.

METHODS

An extensive investigation of literature was done using several worldwide electronic scientific databases like PUBMED, SCOPUS, Science Direct, Google Scholar, etc. The entire manuscript is available in the English language that is used for our various compounds of interest. These databases were thoroughly reviewed and summarized.

RESULTS

Nutraceuticals obtained from various sources play a vital role in the management of peripheral neuropathy associated with diabetes. Treatment with nutraceuticals has been beneficial as an alternative in preventing the progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DPN.

CONCLUSION

Nutraceuticals obtained from different sources like a plant, an animal, and marine have been properly utilized for the safety of health. In our opinion, this review could be of great interest to clinicians, as it offers a complementary perspective on the management of DPN. Trials with a well-defined patient and symptom selection have shown robust pharmacological design as pivotal points to let these promising compounds become better accepted by the medical community.

Differences in Cognitive Function in Women and Men with Diabetic Peripheral Neuropathy with or without Pain

The aim of this study was to analyse the differences in cognitive function between women and men with type-2 diabetes mellitus (DMT2) and diabetic peripheral neuropathy (DPN) with and without diabetic neuropathic pain (DNP), and the factors associated with cognitive function in each sex. A cross-sectional study of 149 patients with DMT2 and DPN was performed. Sociodemographic and clinical variables, Test Your Memory (TYM) for cognitive assessment, anxiety and depression (HADS), quality of life (SF-12v2) and sleep characteristics (MOS-sleep) were measured. A high percentage of women presented cognitive impairment (50% vs. 36.1%) and they scored lower on the TYM (mean = 40.77; SD = 6.03 vs. mean = 42.49; SD = 6.05). Women with DNP scored lower on calculation tasks (3.17 vs. 3.52) than men with DNP, while women without DNP scored lower on retrograde memory (2.70 vs. 3.74), executive function (3.83 vs. 4.25) and similarities (2.51 vs. 3.12) than men without DNP. Being older (B = -0.181) and presenting cardiovascular risk factors (B = -5.059) were associated with worse cognitive function in women, while in men this was associated with older age (B = -0.154), a longer duration of diabetes (B = -0.319) and the presence of depression (B = -0.363). Women with and without DNP obtained worse results in cognitive function. However, the presence of pain had a greater impact on the different dimensions in men.

The upregulation of NLRP3 inflammasome in dorsal root ganglion by ten-eleven translocation methylcytosine dioxygenase 2 (TET2) contributed to diabetic neuropathic pain in mice

BACKGROUND

The nucleotide oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) in dorsal root ganglion (DRG) contributes to pain hypersensitivity in multiple neuropathic pain models, but the function of the NLRP3 in diabetic neuropathic pain (DNP) and the regulation mechanism are still largely unknown. Epigenetic regulation plays a vital role in the controlling of gene expression. Ten-eleven translocation methylcytosine dioxygenase 2 (TET2) is a DNA demethylase that contributes to transcriptional activation. TET2 is also involved in high glucose (HG)-induced pathology.

METHODS

DNP was induced in mice via the intraperitoneal injection of streptozotocin (STZ) for five consecutive days and the mechanical threshold was evaluated in STZ-diabetic mice by using von Frey hairs. The expression level of the NLRP3 pathway and TET2 in DRG were determined through molecular biology experiments. The regulation of the NLRP3 pathway by TET2 was examined in in vitro and in vivo conditions.

RESULTS

In the present research, we first established the DNP model and found that NLRP3 pathway was activated in DRG. The treatment of NLRP3 inhibitor MCC950 alleviated the mechanical allodynia of DNP mice. Then we revealed that in STZ-diabetic mice DRG, the genomic DNA was demethylated, and the expression of DNA demethylase TET2 was increased evidently. Using RNA-sequencing analysis, we found that the expression of Txnip, a gene that encodes a thioredoxin-interacting protein (TXNIP) which mediates NLRP3 activation, was elevated in the DRG after STZ treatment. In addition, knocking down of TET2 expression in DRG using TET2-siRNA suppressed the mRNA expression of Txnip and subsequently inhibited the expression/activation of NLRP3 inflammasome in vitro and in vivo as well as relieved the pain sensitivity of DNP animals.

CONCLUSION

The results suggested that the upregulation of the TXNIP/NLRP3 pathway by TET2 in DRG was involved in the pain hypersensitivity of the DNP model.

Triple-nerve decompression surgery for the treatment of painful diabetic peripheral neuropathy in lower extremities: A study protocol for a randomized controlled trial

Objectives

Painful diabetic peripheral neuropathy (DPN) is often refractory to conventional medications. Triple-nerve decompression was proposed for painful DPN due to the frequent involvement of multiple nerve entrapments in diabetes. However, the role of decompressive surgery remains controversial. This trial aims to assess the efficacy of triple-nerve decompression for patients with painful DPN suggestive of nerve entrapment using a randomized controlled trial (RCT) design.

Methods and analysis

This trial is a single-center RCT and will be conducted in Shanghai Ninth People's Hospital. Enrolled subjects (n = 74) with painful DPN due to nerve compression, which can be detected by nerve conduction studies, will be randomly allocated at a 1:1 ratio into surgical and non-surgical groups. The primary outcome will be measured by 50% responder rates, which is defined as the proportion of subjects with at least 50% reduction of the mean weekly visual analog score (VAS) of pain from baseline after 6 months of treatment. Mean weekly VAS will be additionally evaluated 1 week (W1), 1 month (M1), and 3 months (M3) after treatment to monitor the changes in pain intensity. The secondary outcomes include two-point discrimination (TPD), Toronto clinical scoring system (TCSS), electrophysiological indexes, hospital anxiety and depression scale (HADS), and the medical outcome study short-form 36-item questionnaire (SF-36). A quantitative analgesic questionnaire (QAQ) will be used as a secondary outcome to quantify the analgesic medication weekly. TPD and TCSS will be conducted at W1, M1, M3, and M6 after treatment. Electrophysiological tests, HADS, and SF-36 will be performed at M3 and M6.

Ethics and dissemination

Ethics approval has been obtained from the Ethics Committee of Shanghai Ninth People's Hospital (SH9H-2-21-T323-2). It was registered on the Chinese Clinical Trial Registry website (http://www.chictr.org.cn) on 16 August 2021 with the number ChiCTR2100050049. Written informed consent will be obtained from all participants. The results of this trial will be disseminated via peer-reviewed journals, mass media, and presentations at national and international academic conferences.

The relationship between vascular endothelial growth factor-A serum level and the severity of diabetic peripheral neuropathy

Background and aims

Diabetic peripheral neuropathy (DPN) is a common microvascular complication in type 2 diabetes mellitus (T2DM). The nerve fibers injury is caused by the interaction between metabolic and vascular factors. Vascular endothelial growth factor (VEGF) is an essential growth factor for vascular endothelial cells. We aimed to investigate the relation between VEGF-A serum level and the degree of DPN.

Results

This cross-sectional study was conducted on 81 patients with T2DM. Based on the combined clinical and electrophysiological assessment, 67 patients (82.7%) were diagnosed with peripheral neuropathy of which 32 patients (39.5%) had subclinical neuropathy, whereas 35 patients (43.2%) were confirmed cases of DPN. Patients with DPN had longer duration of DM and higher values of glycosylated hemoglobin (HbA1c). Although the mean serum VEGF-A level in diabetic patients without neuropathy was higher than that in diabetic patients with DPN, this difference did not reach statistical significance (P = 0.07). However, patients with subclinical DPN had significantly higher serum VEGF-A level compared to patients with confirmed DPN (P < 0.001).

Conclusion

DPN was found to be a common finding in the studied sample of T2DM patients. Longer duration of DM and poor glycemic control may be risk factors for development of severe DPN. Low VEGF-A serum levels may lead to more severe DPN in patients with T2DM.

Veratramine ameliorates pain symptoms in rats with diabetic peripheral neuropathy by inhibiting activation of the SIGMAR1-NMDAR pathway

CONTEXT

Veratramine may have a potential therapeutic effect for diabetic peripheral neuropathy (DPN).

OBJECTIVE

To evaluate whether veratramine ameliorates neuropathic pain in a rat diabetic model.

MATERIALS AND METHODS

Sprague-Dawley rats were used for a diabetic model induced by a streptozotocin + high-fat diet. Two months after the induction of the diabetic model, the rats with DPN were screened according to the mechanical pain threshold. The rats with DPN were divided into a model group (n = 12) and a treated group (n = 12). Rats with diabetes, but without peripheral neuropathy, were used in the vehicle group (n = 9). The treatment group received 50 μg/kg veratramine via the tail vein once a day for 4 weeks. During modelling and treatment, rats in all three groups were fed a high-fat diet.

RESULTS

The mechanical withdrawal threshold increased from 7.5 ± 1.9 N to 17.9 ± 2.6 N in DPN rats treated with veratramine. The tolerance time of the treated group to hot and cold ectopic pain increased from 11.8 ± 4.2 s and 3.4 ± 0.8 s to 20.4 ± 4.1 s and 5.9 ± 1.7 s, respectively. Veratramine effectively alleviated L4-L5 spinal cord and sciatic nerve pathological injury. Veratramine inhibited the expression of SIGMAR1 and the phosphorylation of the N-methyl-d-aspartate receptor (NMDAR) Ser896 site in spinal cord tissue, as well as inhibited the formation of SIGMAR1-NMDAR and NMDAR-CaMKII complexes.

DISCUSSION AND CONCLUSIONS

Veratramine may alleviate the occurrence of pain symptoms in rats with DPN by inhibiting activation of the SIGMAR1-NMDAR pathway.