New Advances on Pathophysiology of Diabetes Neuropathy and Pain Management: Potential Role of Melatonin and DPP-4 Inhibitors

Safety Study and Molecular Docking Analysis of Phyto-Constituents from Withania somnifera Leaves: Insights into Dipeptidyl Peptidase-4 (DPP-4) Inhibition and Therapeutic Potential

BACKGROUND

Medicinal plants form the foundation of healthcare systems and modern medicine, offering powerful therapeutic potential to combat a wide range of chronic metabolic disorders.

OBJECTIVE

The present study evaluates the safety of Withania somnifera leaf extracts using rodent modeling for 56 days. It also explores the molecular docking interactions of Withania somnifera (WS) leaf phytoconstituents with the dipeptidyl peptidase-4 (DPP-4) receptor.

METHODOLOGY

A total of 20 rats were divided into 5 groups (G0: Normal diet, G1: 0.25% WS leaves Extract, G3: 0.5% WS leaves Extract, G4: 0.5% WS leaves powder, and G5: 1% WS leaves powder) for 56 days. The organ-to-body weight ratio, LFTs, RFTs, and hematological profile were determined in the 4th and 8th weeks. On the other hand, the structures of compounds identified from the methanolic extract of W. somnifera leaves were modified into PDBQT format to perform molecular docking.

RESULTS

The results showed that all parameters varied within normal ranges. The hematological parameters were higher in G2 after the 28th day compared to the values after the 56th day. The maximum values of serum glucose and lipid parameters were found in the G3 group as compared to other groups, while hepato-renal markers were high in G0. Molecular docking revealed the binding affinity of w-02, w-03, w-04, w-05, and w-07 with DPP-4 receptors; moreover, w-04 had the highest binding affinity of -6.4 kcal/mol.

CONCLUSION

The 0.5% leaves extract of W. somnifera revealed positive effect on hematological and biochemical profile of rats without causing any adverse effects.

Neuro-Nutritional Approach to Neuropathic Pain Management: A Critical Review

Pain is a significant global public health issue that can interfere with daily activities, sleep, and interpersonal relationships when it becomes chronic or worsens, ultimately impairing quality of life. Despite ongoing efforts, the efficacy of pain treatments in improving outcomes for patients remains limited. At present, the challenge lies in developing a personalized care and management plan that helps to maintain patient activity levels and effectively manages pain. Neuropathic pain is a chronic condition resulting from damage to the somatosensory nervous system, significantly impacting quality of life. It is partly thought to be caused by inflammation and oxidative stress, and clinical research has suggested a link between this condition and diet. However, these links are not yet well understood and require further investigation to evaluate the pathways involved in neuropathic pain. Specifically, the question remains whether supplementation with dietary antioxidants, such as melatonin, could serve as a potential adjunctive treatment for neuropathic pain modulation. Melatonin, primarily secreted by the pineal gland but also produced by other systems such as the digestive system, is known for its anti-inflammatory, antioxidant, and anti-aging properties. It is found in various fruits and vegetables, and its presence alongside other polyphenols in these foods may enhance melatonin intake and contribute to improved health. The aim of this review is to provide an overview of neuropathic pain and examine the potential role of melatonin as an adjunctive treatment in a neuro-nutritional approach to pain management.

Effect of high-dose N-acetyl cysteine on the clinical outcome of patients with diabetic peripheral neuropathy: a randomized controlled study

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a vastly common and bothersome disorder with a clinically challenging course of treatment affecting patients with diabetes. This study aimed to evaluate the efficacy and safety of high dose oral N-acetyl cysteine (NAC) as adjuvant therapy on clinical outcome of DPN.

METHODS

A prospective, randomized, parallel, open label, controlled clinical trial. Ninety eligible DPN patients were randomly assigned to either control group receiving standard of care or NAC group receiving standard of care treatment and NAC at a dose of 2400 mg/day for 12 weeks. Glutathione peroxidase (GPx), nuclear factor erythoid-2 related factor (NRF-2) and tumor necrosis factor (TNF) were measured at baseline and after 12 weeks to assess anti-oxidant and anti-inflammatory properties. Michigan neuropathy screening instrument (MNSI), Toronto clinical neuropathy score (TCNS), Diabetic neuropathy score (DNS), Diabetes-39 quality of life questionnaire (DQOL) and pain score were assessed at baseline and after 12 weeks.

RESULTS

NAC group showed a significant increase (p < 0.05) in NRF-2 by 25.3% and GPx by 100% and a decline of 21.45% in TNF-alpha levels versus controls that reported a decline in NRF-2 and GPx and an increase in TNF-alpha. HgbA1C and AST levels significantly decreased in NAC versus controls (7.2 ± 1 vs 8 ± 1.1, p = 0.028 and 29.1 vs 55.4, p = 0.012) respectively. NAC administration resulted in a significant decline in MNSA, TCNS, DNS and pain scores versus controls that showed increase in all scores. The QOL total score and the anxiety and energy and mobility domain scores significantly decreased in the NAC group versus controls, p < 0.001.

CONCLUSION

High dose NAC administered for 12 weeks modulated inflammation by reducing TNF-alpha and increasing GPx and NRF2 versus controls. NAC improved clinical outcomes of DPN reflected by a decline in neuropathy and pain scores and an improvement in QOL.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04766450.

Tauroursodeoxycholic Acid (TUDCA) Relieves Streptozotocin (STZ)-Induced Diabetic Rat Model via Modulation of Lipotoxicity, Oxidative Stress, Inflammation, and Apoptosis

Tauroursodeoxycholic acid (TUDCA) is approved for the treatment of liver diseases. However, the antihyperglycemic effects/mechanisms of TUDCA are still less clear. The present study aimed to evaluate the antidiabetic action of TUDCA in streptozotocin (STZ)-induced type 2 diabetes mellitus (T2DM) in rats. Fifteen adult Wistar albino male rats were randomly divided into three groups (n = five in each): control, diabetic (STZ), and STZ+TUDCA. The results showed that TUDCA treatment significantly reduced blood glucose, HbA1c%, and HOMA-IR as well as elevated the insulin levels in diabetic rats. TUDCA therapy increased the incretin GLP-1 concentrations, decreased serum ceramide synthase (CS), improved the serum lipid profile, and restored the glycogen content in the liver and skeletal muscles. Furthermore, serum inflammatory parameters (such as TNF-α, IL-6, IL-1ß, and PGE-2) were substantially reduced with TUDCA treatment. In the pancreas, STZ+TUDCA-treated rats underwent an obvious enhancement of enzymatic (CAT and SOD) and non-enzymatic (GSH) antioxidant defense systems and a marked decrease in markers of the lipid peroxidation rate (MDA) and nitrosative stress (NO) compared to STZ-alone. At the molecular level, TUDCA decreased the pancreatic mRNA levels of iNOS and apoptotic-related factors (p53 and caspase-3). In conclusion, TUDCA may be useful for diabetes management and could be able to counteract diabetic disorders via anti-hyperlipidemic, antioxidant, anti-inflammatory, and anti-apoptotic actions.

Oxidative Stress in Diabetic Peripheral Neuropathy: Pathway and Mechanism-Based Treatment

Diabetic peripheral neuropathy (DPN) is a major complication of diabetes mellitus with a high incidence. Oxidative stress, which is a crucial pathophysiological pathway of DPN, has attracted much attention. The distortion in the redox balance due to the overproduction of reactive oxygen species (ROS) and the deregulation of antioxidant defense systems promotes oxidative damage in DPN. Therefore, we have focused on the role of oxidative stress in the pathogenesis of DPN and elucidated its interaction with other physiological pathways, such as the glycolytic pathway, polyol pathway, advanced glycosylation end products, protein kinase C pathway, inflammation, and non-coding RNAs. These interactions provide novel therapeutic options targeting oxidative stress for DPN. Furthermore, our review addresses the latest therapeutic strategies targeting oxidative stress for the rehabilitation of DPN. Antioxidant supplements and exercise have been proposed as fundamental therapeutic strategies for diabetic patients through ROS-mediated mechanisms. In addition, several novel drug delivery systems can improve the bioavailability of antioxidants and the efficacy of DPN.

Carnosine Alleviates Knee Osteoarthritis and Promotes Synoviocyte Protection via Activating the Nrf2/HO-1 Signaling Pathway: An In-Vivo and In-Vitro Study

The most common joint disease in the elderly is knee osteoarthritis (OA). It is distinguished by cartilage degradation, subchondral bone loss, and a decrease in joint space. We studied the effects of carnosine (CA) on knee OA in male Wistar rats. OA is induced by anterior cruciate ligament transection combined with medial meniscectomy (ACLT+MMx) method and in vitro studies are conducted in fibroblast-like synoviocyte cells (FLS). The pain was assessed using weight-bearing and paw-withdrawal tests. CA supplementation significantly reduced pain. The enzyme-linked immunosorbent assay (ELISA) method was used to detect inflammatory proteins in the blood and intra-articular synovial fluid (IASF), and CA reduced the levels of inflammatory proteins. Histopathological studies were performed on knee-tissue samples using toluidine blue and hematoxylin and eosin (H and E) assays. CA treatment improved synovial protection and decreased cartilage degradation while decreasing zonal depth lesions. Furthermore, Western blotting studies revealed that the CA-treated group activated nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase (HO-1) and reduced the expression of cyclooxygenase-2 (COX-2). FLS cells were isolated from the knee joints and treated with IL-1β to stimulate the inflammatory response and increase reactive oxygen species (ROS). The matrix metalloproteinase protein (MMP's) levels (MMP-3, and MMP-13) were determined using the reverse transcription-polymerase chain reaction (RT-PCR), and CA treatment reduced the MMP's expression levels. When tested using the 2',7'-dicholorodihydrofluroscene diacetate (DCFDA) assay and the 5,5',6,6'-tetracholoro-1,1',3,3'-tertraethylbenzimidazolcarboc janine iodide (JC-1) assay in augmented ROS FLS cells, CA reduced the ROS levels and improved the mitochondrial membrane permeability. This study's investigation suggests that CA significantly alleviates knee OA both in vitro and in vivo.