The Role of Oxidative Stress, Mitochondrial Function, and Autophagy in Diabetic Polyneuropathy

Enhancing S-nitrosoglutathione reductase decreases S-nitrosylation of ERO1α and reduces neuronal death in secondary traumatic brain injury

Traumatic brain injury (TBI) has the highest incidence of all common neurological disorders, along with high mortality and disability rates. Pathological conversion of excess nitric oxide (NO) to S-nitrosoglutathion (GSNO) after TBI leads to high S-nitrosylation of intracellular proteins, causing nitrative stress. GSNO reductase (GSNOR) plays an important role by regulating GSNO and SNO-proteins (PSNOs) and as a redox regulator of the nervous system. However, the effect of GSNOR on protein S-nitrosylation in secondary brain injury after TBI is not clear. In vivo TBI model was established in male C57BL/6 mice via controlled cortical impact (CCI). Neuron-targeted GSNOR-overexpression adeno-associated virus (AAV) was constructed and administered to mice by stereotactic cortical injection. The results showed that NO, GSNO, neuronal protein S-nitrosylation and neuronal death increased after TBI, while the level and activity of GSNOR decreased. Overexpression of GSNOR by AAV decreased GSNO and NO and improved short-term neurobehavioral outcomes in mice. GSNOR overexpression can reduce endoplasmic reticulum stress and neuronal death by reducing the S-nitrosylation of ERO1α via H2O2 generation and plays a neuroprotective role. In conclusion, our results suggest that GSNOR regulating S-nitrosylation of ERO1α may participate in neuronal death, and overexpression of GSNOR in neurons after experimental brain injury alleviates secondary brain injury. Our research provides a potential therapeutic approach for the treatment of TBI.

The efficacy of acupuncture for diabetic peripheral neuropathy: a systematic review and meta-analysis of randomized controlled trails

Objective

To systematically evaluate the clinical efficacy of acupuncture in the treatment of diabetic peripheral neuropathy (DPN).

Methods

Randomized controlled trial (RCT) of acupuncture for diabetic peripheral neuropathy in Chinese Knowledge Network (CNKI), Wanfang database, VIP database (VIP), PubMed, web of science, cochrane library, AMED and CINAHL were searched by computer since the establishment of the database. All publications in English and Chinese as of 30 December 2023 will be searched, without country or article type restrictions. Study selection, data extraction and evaluation were performed independently by two researchers. Risk of bias was assessed using the Cochrane risk assessment tool, and Meta-analysis was performed using RevMan5.3 software.

Results

DPN has good effective rate in acupuncture than conventional western medicine alone. However, the above conclusions need to be verified by larger samples and higher quality randomized controlled trials. ① Acupuncture treated DPN more effective than drug (RR = 1.38, 95%CI = 1.26 ~ 1.51, Z = 6.93, p < 0.00001), DPN of patients with acupuncture plus drug (RR = 1.38, 95%CI = 1.05 ~ 1.82, Z = 2.28, p = 0.02), There was no significant difference between acupuncture and usual care (RR = 2.41, 95%CI = 0.70 ~ 8.29, Z = 1.39, p = 0.16); ② Acupuncture treatment is superior to drug group in improving the SNCV of the median nerve (MD = 1.65, 95%CI = 0.74 ~ 2.57,Z = 3.55, p = 0.0004), sham needle treatment (MD = 0.50, 95%CI = 0.17 ~ 0.83, Z = 2.95, p = 0.003), Acupuncture plus drug was superior to drug in improving the SNCV of the median nerve (MD = 3.29, 95%CI = 2.55 ~ 4.03, Z = 8.70, p < 0.00001); ③ Acupuncture treatment is superior to drug group in improving the MNCV of the median nerve (MD = 2.24, 95%CI = 0.50 ~ 3.98, Z = 2.52, p = 0.01), and sham needle treatment (MD = 0.20, 95%CI = -0.03 ~ 0.43, Z = 1.69, p = 0.09), Acupuncture plus drug was superior to drug group in improving the MNCV of the median nerve (MD = 2.63, 95%CI = 1.83 ~ 3.42, Z = 6.46, p < 0.00001); ④ Acupuncture is better to drug group in improving SNCV of common peroneal nerve (MD = 1.67, 95%CI = 0.21 ~ 3.13, Z = 2.24, p = 0.02); ⑤ Acupuncture treatment is superior to drug group in improving the MNCV of the common peroneal nerve (MD = 2.03, 95%CI = 1.37 ~ 0.69, Z = 6.04, p < 0.00001), Acupuncture plus drug outperformed MNCV in improving the common peroneal nerve (MD = 4.23, 95%CI = -0.16 ~ 8.62, Z = 1, 89, p = 0.06); ⑥ Acupuncture treatment is superior to drug group in improving the SNCV of the tibial nerve (MD = 1.58, 95%CI = 0.85 ~ 2.30, Z = 4.26, p < 0.0001); ⑦ There was no significant difference between acupuncture treatment and drug group in improving the MNCV of the tibial nerve (MD =1.55, 95%CI = -0.59 ~ 3.68, Z = 1.42, p = 0.16); ⑧ Acupuncture plus drug is better than medication in reducing VAS (MD = -2.35, 95%CI = -3.78 ~ -0.93, Z = 3.23, p = 0.001), Acupuncture plus usual care is superior to usual caret (MD = -28.70, 95%CI = -39.50 ~ 17.90, Z = 5.21, p < 0.00001), There was no significant difference between acupuncture and sham needle treatment (MD = -4.00, 95%CI = -18.32 ~ 10.32, Z = 0.55, p = 0.58).

Conclusion

Compared with drug, usual care, and sham AT, AT has a better response rate and more favorable effect in improving nerve conduction velocity. The combination of AT and drug demonstrates a more significant improvement compared to drug alone. The combination of AT and usual care improves DPN symptoms more effectively than usual care. However, the above conclusions need to be verified by larger samples and higher quality randomized controlled trials.

Systematic review registration

[https://www.crd.york.ac.uk/], identifier [CRD42023451575].

Antiapoptotic and antinociceptive effects of Achillea millefolium L. aqueous extract in rats with experimental painful diabetic neuropathy

Background and purpose

Neuropathy is one of the common complications of diabetes mellitus. This study aimed to determine the analgesic and antiapoptotic effects of the aqueous extract of Achillea millefolium L. (Ach) in rats with experimental painful diabetic neuropathy by behavioral and molecular procedures.

Experimental approach

Thirty male Wistar rats were divided into 5 groups including control, diabetes + saline, and diabetes + Ach extract (doses of 150, 300, and 600 mg/kg/day for 3 weeks, orally). A tail-flick test was performed to assess the pain threshold in different groups. Western blotting test was used to evaluate the apoptotic (Bax, Bcl2, cleaved caspase-3, and cytochrome-c) and inflammatory (TNF-α and NF-kB) protein factors in the lumbar portion of the spinal cord tissue. Also, commercial assay kits were used to evaluate oxidative stress factors (MDA, GPx, and SOD enzyme activity) in the lumbar portion of the spinal cord tissue.

Findings/Results

Results showed that administering Ach extract at the doses of 300 and 600 mg/kg/day significantly increased the nociception threshold in treated diabetic animals compared to untreated diabetic animals. Moreover, the treatment of diabetic animals with Ach extract (300 and 600 mg/kg/day) significantly reduced the oxidative stress, inflammation, and apoptosis biochemical indicators in the lumbar spinal cord tissue compared to the untreated diabetic group.

Conclusion and implications

The findings showed that Ach extract has neuroprotective and anti-nociceptive effects in rats with diabetic neuropathy. The effects can be due to the inhibition of oxidative stress, inflammation, and apoptosis in the spinal cord tissue.

Linalool exerts antioxidant activity in a rat model of diabetes by increasing catalase activity without antihyperglycemic effect

Diabetes mellitus (DM) is a prevalent metabolic disorder often accompanied by oxidative stress, which contributes to various diabetic complications. Investigating the antioxidant activity of linalool (LIN) is crucial as it may offer a natural therapeutic approach to mitigate oxidative damage in DM. The aim of the present study was to investigate the antioxidant activity of LIN in a DM rat model. A total of 40 male Wistar albino rats (age, 8 weeks; weight, 250-300 g) were used. CONTROL and DM groups were administered physiological saline solution by oral gavage for 21 days. In rats in the DM + LIN and LIN groups, 100 mg/kg LIN was administered intragastrically after streptozotocin injection (n=10 per group). In the first (48 h after STZ injection), second (1 week later), third (2 weeks later), and fourth (3 weeks later) blood glucose measurements, a statistically significant increase was found in the blood glucose values of the DM and DM + LIN groups compared with those of the CONTROL group. During the 21-day experimental period, there was no reduction in blood glucose levels of the DM + LIN group. Consequently, no discernible anti-hyperglycemic effect of LIN was observed. Catalase enzyme activity, superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) levels and glutathione (GSH) levels were measured spectrophotometrically. All assays were conducted according to the protocols provided in the respective kits. The results were analyzed to assess the oxidative status and antioxidant capacity in the experimental groups. Catalase (CAT) activity was decreased in the DM group compared with that in the CONTROL group in both the serum and liver. However, LIN administration restored CAT activity in the DM + LIN group to the level of the CONTROL group. In the liver, the DM + LIN-treated group showed a notable reduction in malondialdehyde (MDA) levels compared with those in the DM group. In conclusion, the present results suggest that the antioxidant properties of LIN may have a regulatory effect on the oxidative status in diabetes-affected systems, potentially offering therapeutic benefits in managing oxidative stress associated with diabetes.

Maltol Improves Peripheral Nerve Function by Inhibiting Schwann Cell Apoptosis via the PERK/eIF2α/CHOP Pathway and MME Upregulation in Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is the most prevalent chronic complication among diabetic patients and a primary risk factor contributing to the deterioration of diabetic foot conditions. The pathogenesis of DPN remains complex and not fully understood, and there are hardly any effective treatment drugs. Maltol (3-hydroxy-2-methyl-4-pyranone) has demonstrated antioxidant and anti-inflammatory properties. However, the potential role of maltol in the treatment of DPN remains unclear. This study aimed to assess maltol's effects on DPN rats and high glucose (HG)/palmitic acid (PA)-induced rat Schwann cells (RSC96). The results indicated maltol's capacity to enhance peripheral nerve function in DPN rats. In RSC96 cells stimulated with high HG and PA, maltol treatment reduced DPN markers and apoptosis-related proteins. Functional enrichment analysis of differentially expressed genes revealed that endoplasmic reticulum (ER) stress pathways were involved in this process. Western blot results demonstrated the activation of ER stress pathway in HG/PA-induced RSC96 cells, with maltol attenuating ER stress-related protein expression. Furthermore, the knockdown of Membrane metallo-endopeptidase (MME) reversed maltol's effects on apoptosis-related protein expression, suggesting a potential therapeutic role for maltol via MME in treating DPN. These findings indicate that maltol may hold promise as a therapeutic agent for DPN treatment.

Type 2 diabetes microenvironment promotes the development of Parkinson's disease by activating microglial cell inflammation

Objective

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, and type 2 diabetes (T2DM) and PD are influenced by common genetic and environmental factors. Mitochondrial dysfunction and inflammation are common pathogenic mechanisms of both diseases. However, the close association between PD and T2DM and the specific relationship between them are not yet clear. This study aimed to reveal the specific connection between the two diseases by establishing a mouse model of comorbid PD and T2DM, as well as a Bv2 cell model.

Methods

C57BL/6 mouse were used to construct a model of PD with T2DM using streptozotocin and rotenone, while Bv2 cells were used to simulate the microenvironment of PD and T2DM using rotenone and palmitate. Behavioral tests were conducted to assess any differences in motor and cognitive functions in mouse. Immunohistochemistry was used to analyze the number of dopaminergic neurons in the substantia nigra region of mouse. Western blotting was used to detect the expression levels of TH, P-NFκB, NFκB, Cyclic GMP-AMP synthase (cGAS), and Stimulator of interferon genes (STING) proteins in the substantia nigra region of mouse and Bv2 cells. qRT-PCR was used to analyze the expression levels of IL1β, IL6, and TNF-α. Seahorse technology was used to assess mitochondrial function in Bv2 cells.

Results

T2DM exacerbated the motor and cognitive symptoms in mouse with PD. This effect may be mediated by disrupting mitochondrial function in microglial cells, leading to damaged mtDNA leakage into the cytoplasm, subsequently activating the cGAS-STING pathway and downstream P-NFκB/NFκB proteins, triggering an inflammatory response in microglial cells. Microglial cells release inflammatory factors such as IL1β, IL6, and TNF-α, exacerbating neuronal damage caused by PD.

Conclusion

Our study results suggest that T2DM may exacerbate the progression of PD by damaging mitochondrial function, and activating microglial cell inflammation. The detrimental effects on Parkinson's disease may be achieved through the activating of the cGAS-STING protein pathway.

New insights into the interplay between autophagy, gut microbiota and insulin resistance in metabolic syndrome

Metabolic syndrome (MetS) is a widespread and multifactorial disorder, and the study of its pathogenesis and treatment remains challenging. Autophagy, an intracellular degradation system that maintains cellular renewal and homeostasis, is essential for maintaining antimicrobial defense, preserving epithelial barrier integrity, promoting mucosal immune response, maintaining intestinal homeostasis, and regulating gut microbiota and microbial metabolites. Dysfunctional autophagy is implicated in the pathological mechanisms of MetS, involving insulin resistance (IR), chronic inflammation, oxidative stress, and endoplasmic reticulum (ER) stress, with IR being a predominant feature. The study of autophagy represents a valuable field of research with significant clinical implications for identifying autophagy-related signals, pathways, mechanisms, and treatment options for MetS. Given the multifactorial etiology and various potential risk factors, it is imperative to explore the interplay between autophagy and gut microbiota in MetS more thoroughly. This will facilitate the elucidation of new mechanisms underlying the crosstalk among autophagy, gut microbiota, and MetS, thereby providing new insights into the diagnosis and treatment of MetS.

Expert opinion on screening, diagnosis and management of diabetic peripheral neuropathy: a multidisciplinary approach

The proposed expert opinion aimed to address the current knowledge on conceptual, clinical, and therapeutic aspects of diabetic peripheral neuropathy (DPN) and to provide a guidance document to assist clinicians for the best practice in DPN care. The participating experts consider the suspicion of the disease by clinicians as a key factor in early recognition and diagnosis, emphasizing an improved awareness of the disease by the first-admission or referring physicians. The proposed "screening and diagnostic" algorithm involves the consideration of DPN in a patient with prediabetes or diabetes who presents with neuropathic symptoms and/or signs of neuropathy in the presence of DPN risk factors, with careful consideration of laboratory testing to rule out other causes of distal symmetric peripheral neuropathy and referral for a detailed neurological work-up for a confirmative test of either small or large nerve fiber dysfunction in atypical cases. Although, the first-line interventions for DPN are currently represented by optimized glycemic control (mainly for type 1 diabetes) and multifactorial intervention (mainly for type 2 diabetes), there is a need for individualized pathogenesis-directed treatment approaches for DPN. Alpha-lipoic acid (ALA) seems to be an important first-line pathogenesis-directed agent, given that it is a direct and indirect antioxidant that works with a strategy targeted directly against reactive oxygen species and indirectly in favor of endogenous antioxidant capacity for improving DPN conditions. There is still a gap in existing research in the field, necessitating well-designed, robust, multicenter clinical trials with sensitive endpoints and standardized protocols to facilitate the diagnosis of DPN via a simple and effective algorithm and to track progression of disease and treatment response. Identification of biomarkers/predictors that would allow an individualized approach from a potentially disease-modifying perspective may provide opportunities for novel treatments that would be efficacious in early stages of DPN, and may modify the natural course of the disease. This expert opinion document is expected to increase awareness among physicians about conceptual, clinical, and therapeutic aspects of DPN and to assist them in timely recognition of DPN and translating this information into their clinical practice for best practice in the management of patients with DPN.

Enteric neuropathy in diabetes: Implications for gastrointestinal function

Diabetes, commonly known for its metabolic effects, also critically affects the enteric nervous system (ENS), which is essential in regulating gastrointestinal (GI) motility, secretion, and absorption. The development of diabetes-induced enteric neuropathy can lead to various GI dysfunctions, such as gastroparesis and irregular bowel habits, primarily due to disruptions in the function of neuronal and glial cells within the ENS, as well as oxidative stress and inflammation. This editorial explores the pathophysiological mechanisms underlying the development of enteric neuropathy in diabetic patients. Additionally, it discusses the latest advances in diagnostic approaches, emphasizing the need for early detection and intervention to mitigate GI complications in diabetic individuals. The editorial also reviews current and emerging therapeutic strategies, focusing on pharmacological treatments, dietary management, and potential neuromodulatory interventions. Ultimately, this editorial highlights the necessity of a multidisciplinary approach in managing enteric neuropathy in diabetes, aiming to enhance patient quality of life and address a frequently overlooked complication of this widespread disease.

Non-coding RNAs in diabetic peripheral neuropathy: their role and mechanisms underlying their effects

Diabetic peripheral neuropathy (DPN) is a complication of diabetes with a high rate of disability. However, current clinical treatments for DPN are suboptimal. Non-coding RNAs (ncRNAs) are a type of RNAs that are not translated into proteins. NcRNAs perform functions that regulate epigenetic modifications, transcriptional or post-transcriptional regulators of proteins, and thus participate in the physiological and pathological processes of the body. NcRNAs play a role in the progress of DPN by affecting the processes of inflammation, oxidative stress, cellular autophagy or apoptosis. Therefore, ncRNAs treatment is regarded as a promising therapeutic approach for DPN. In addition, since some ncRNAs present stably in the blood of DPN patients, they are considered as potential biomarkers that contribute to early clinical diagnosis. In this paper, we review the studies on the role of ncRNAs in DPN in the last decade, and discuss the mechanisms of ncRNAs, aiming to provide a reference for the future research on the treatment and early diagnosis of DPN.

Novel drugs affecting diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) poses a significant threat, affecting half of the global diabetic population and leading to severe complications, including pain, impaired mobility, and potential amputation. The delayed manifestation of diabetic neuropathy (DN) makes early diagnosis challenging, contributing to its debilitating impact on individuals with diabetes mellitus (DM). This review examines the multifaceted nature of DPN, focusing on the intricate interplay between oxidative stress, metabolic pathways, and the resulting neuronal damage. It delves into the challenges of diagnosing DN, emphasizing the critical role played by hyperglycemia in triggering these cascading effects. Furthermore, the study explores the limitations of current neuropathic pain drugs, prompting an investigation into a myriad of pharmaceutical agents tested in both human and animal trials over the past decade. The methodology scrutinizes these agents for their potential to provide symptomatic relief for DPN. The investigation reveals promising results from various pharmaceutical agents tested for DPN relief, showcasing their efficacy in ameliorating symptoms. However, a notable gap persists in addressing the underlying problem of DPN. The results underscore the complexity of DPN and the challenges in developing therapies that go beyond symptomatic relief. Despite advancements in treating DPN symptoms, there remains a scarcity of options addressing the underlying problem. This review consolidates the state-of-the-art drugs designed to combat DPN, highlighting their efficacy in alleviating symptoms. Additionally, it emphasizes the need for a deeper understanding of the diverse processes and pathways involved in DPN pathogenesis.

From diabetic hyperglycemia to cerebrovascular Damage: A narrative review

Diabetes mellitus is a globally significant disease that can lead to systemic complications, particularly vascular damage, including cardiovascular and cerebrovascular diseases of relevance. The physiological changes resulting from the imbalance in blood glucose levels play a crucial role in initiating vascular endothelial damage. Elevated glucose levels can also penetrate the central nervous system, triggering diabetic encephalopathy characterized by oxidative damage to brain components and activation of alternative and neurotoxic pathways. This brain damage increases the risk of ischemic stroke, a leading cause of mortality worldwide and a major cause of disability among surviving patients. The aim of this review is to highlight important pathways related to hyperglycemic damage that extend to the brain and result in vascular dysfunction, ultimately leading to the occurrence of a stroke. Understanding how diabetes mellitus contributes to the development of ischemic stroke and its impact on patient outcomes is crucial for implementing therapeutic strategies that reduce the incidence of diabetes mellitus and its complications, ultimately decreasing morbidity and mortality associated with the disease.

Vincamine as an agonist of G-protein-coupled receptor 40 effectively ameliorates diabetic peripheral neuropathy in mice

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes, which has yet no curable medication. Neuroinflammation and mitochondrial dysfunction are tightly linked to DPN pathology. G-protein-coupled receptor 40 (GPR40) is predominantly expressed in pancreatic β-cells, but also in spinal dorsal horn and dorsal root ganglion (DRG) neurons, regulating neuropathic pain. We previously have reported that vincamine (Vin), a monoterpenoid indole alkaloid extracted from Madagascar periwinkle, is a GPR40 agonist. In this study, we evaluated the therapeutic potential of Vin in ameliorating the DPN-like pathology in diabetic mice. Both STZ-induced type 1 (T1DM) and db/db type 2 diabetic (T2DM) mice were used to establish late-stage DPN model (DPN mice), which were administered Vin (30 mg·kg-1·d-1, i.p.) for 4 weeks. We showed that Vin administration did not lower blood glucose levels, but significantly ameliorated neurological dysfunctions in DPN mice. Vin administration improved the blood flow velocities and blood perfusion areas of foot pads and sciatic nerve tissues in DPN mice. We demonstrated that Vin administration protected against sciatic nerve myelin sheath injury and ameliorated foot skin intraepidermal nerve fiber (IENF) density impairment in DPN mice. Moreover, Vin suppressed NLRP3 inflammasome activation through either β-Arrestin2 or β-Arrestin2/IκBα/NF-κB signaling, improved mitochondrial dysfunction through CaMKKβ/AMPK/SIRT1/PGC-1α signaling and alleviated oxidative stress through Nrf2 signaling in the sciatic nerve tissues of DPN mice and LPS/ATP-treated RSC96 cells. All the above-mentioned beneficial effects of Vin were abolished by GPR40-specific knockdown in dorsal root ganglia and sciatic nerve tissues. Together, these results support that pharmacological activation of GPR40 as a promising therapeutic strategy for DPN and highlight the potential of Vin in the treatment of this disease.

Effects of 4-hexylresorcinol on facial skeletal development in growing rats: Considerations for diabetes

Objective

: To investigate the long-term effects of 4-hexylresorcinol (4HR) on facial skeletal growth in growing male rats, with a focus on diabetic animal models.

Methods

: Forty male rats were used. Of them, type 1 diabetes mellitus was induced in 20 animals by administering 40 mg/kg streptozotocin (STZ), and they were assigned to either the STZ or 4HR-injected group (STZ/4HR group). The remaining 20 healthy rats were divided into control and 4HR groups. We administered 4HR subcutaneously at a weekly dose of 10 mg/kg until the rats were euthanized. At 16 weeks of age, whole blood was collected, and micro-computed tomography of the skull and femur was performed.

Results

: All craniofacial linear measurements were smaller in the STZ group than in the control group. The mandibular molar width was significantly smaller in the 4HR group than in the control group (P = 0.031) but larger in the STZ/4HR group than in the STZ group (P = 0.011). Among the diabetic animals, the STZ/4HR group exhibited significantly greater cortical bone thickness, bone mineral density, and bone volume than the STZ group. Serum testosterone levels were also significantly higher in the STZ/4HR group than in the STZ group.

Conclusions

: 4HR administration may have divergent effects on mandibular growth and bone mass in healthy and diabetic rats. In the context of diabetes, 4HR appears to have beneficial effects, potentially through the modulation of mitochondrial respiration.

Effects of autophagy inhibitor 3-methyladenine on a diabetic mice model

AIM

To investigate the role of autophagy inhibitor 3-methyladenine (3-MA) on a diabetic mice model (DM) and the potential mechanism.

METHODS

Male C57BL/6J mice were randomly divided into a normal control group (NC group) and an DM group. DM were induced by multiple low-dose intraperitoneal injection of streptozotocin (STZ) 60 mg/kg·d for 5 consecutive days. DM mice were randomly subdivided into untreated group (DM group), 3-MA (10 mg/kg·d by gavage) treated group (DM+3-MA group) and chloroquine (CQ; 50 mg/kg by intraperitoneal injection) treated group (DM+CQ group). The fasting blood glucose (FBG) levels were recorded every week. At the end of experiment, retinal samples were collected. The expression levels of pro-apoptotic proteins cleaved caspase-3, cleaved poly ADP-ribose polymerase 1 (PARP1) and Bax, anti-apoptotic protein Bcl-2, fibrosis-associated proteins Fibronectin and type 1 collagen α1 chain (COL1A1), vascular endothelial growth factor (VEGF), inflammatory factors interleukin (IL)-1β and tumor necrosis factor (TNF)-α, as well as autophagy related proteins LC3, Beclin-1 and P62 were determined by Western blotting. The oxidative stress indicators 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) were detected by commercial kits.

RESULTS

Both 3-MA and CQ had short-term hypoglycemic effect on FBG and reduced the expression of VEGF and inflammatory factors IL-1β and TNF-α in DM mice. 3-MA also significantly alleviated oxidative stress indicators 8-OHdG and MDA, decreased the expression of fibrosis-related proteins Fibronectin and COL1A1, pro-apoptotic proteins cleaved caspase-3, cleaved PARP1, as well as the ratio of Bax/Bcl-2. CQ had no significant impact on the oxidative stress indicators, fibrosis, and apoptosis related proteins. The results of Western blotting for autophagy related proteins showed that the ratio of LC3 II/LC3 I and the expression of Beclin-1 in the retina of DM mice were decreased by 3-MA treatment, and the expression of P62 was further increased by CQ treatment.

CONCLUSION

3-MA has anti-apoptotic and anti-fibrotic effects on the retina of DM mice, and can attenuate retinal oxidative stress, VEGF expression and the production of inflammatory factors in the retina of DM mice. The underlying mechanism of the above effects of 3-MA may be related to its inhibition of early autophagy and hypoglycemic effect.

Effects of noopept on ocular, pancreatic and renal histopathology in streptozotocin induced prepubertal diabetic rats

Diabetes mellitus (DM) is a chronic disease at all ages including childhood and puberty. Failure to treat DM can cause retinopathy, nephropathy and neuropathy. Endocrine and metabolic changes during the pubertal period complicate management of DM. Noopept is a cognitive enhancer that exhibits antidiabetic properties. We investigated the effect of noopept on the histopathology of the cornea, retina, kidney and pancreas in pubertal diabetic rats. We allocated 60 prepubertal male rats randomly into six groups of 10: untreated control (C), DM control (DC), noopept control (NC), DM + noopept (D + N), DM + insulin (D + I) and DM + insulin + noopept (D + I + N). DM was induced by streptozotocin in the DC, D + N, D + I and D + I + N groups. Noopept was administered to the NC, D + N and D + I + N groups; insulin was administered to the D + I and D + I + N groups for 14 days. On day 18 of the experiment, animals were sacrificed and eyes, kidneys and pancreata were excised for histological investigation. Renal tubule diameter and corneal and retinal thickness were increased significantly in DC groups compared to the control group. The D + I, D + N and D + I + N groups exhibited fewer DM induced pathological changes than the DC group. The D + I + N group exhibited no significant differences in renal tubule diameter and corneal and retinal thickness compared to the DC group. Our findings suggest that noopept is protective against DM end organ complications in streptozotocin induced diabetic pubertal rats.

Controversial Role of Folic Acid on Diabetic Auditory Neuropathy

OBJECTIVE

Diabetic auditory neuropathy (DAN) is a common complication of diabetes that seriously affects the quality of life in patients. In this study, we investigate the role of folic acid in the treatment of DAN in an experimental rat model.

METHODS

Thirty-two Sprague-Dawley rats were equally divided into four groups: group 1, normal; group 2, diabetic rats; and groups 3 and 4, diabetic rats treated with folic acid (40 and 80 mg/kg, respectively). We used some tools to investigate the therapeutic effect of folic acid on DAN. We evaluated auditory brain stem response (ABR), estimated the volume and number of spiral ganglion and the volume of stria vascularis and spiral ligament by the stereological method, and measured the blood levels of homocysteine (HCY), malondialdehyde (MDA), and superoxide dismutase (SOD).

RESULTS

Our study showed that folic acid treatment was not significantly effective in improving structural and functional disorders in DAN, even though its effectiveness in reducing HCY (P < 0.001) and MDA (P < 0.05) as oxidative biomarkers was significant.

CONCLUSION

Folic acid is not effective in relieving morphological and functional disorders in DAN.

Towards prevention of diabetic peripheral neuropathy: clinical presentation, pathogenesis, and new treatments

Diabetic peripheral neuropathy (DPN) occurs in up to half of individuals with type 1 or type 2 diabetes. DPN results from the distal-to-proximal loss of peripheral nerve function, leading to physical disability and sometimes pain, with the consequent lowering of quality of life. Early diagnosis improves clinical outcomes, but many patients still develop neuropathy. Hyperglycaemia is a risk factor and glycaemic control prevents DPN development in type 1 diabetes. However, glycaemic control has modest or no benefit in individuals with type 2 diabetes, probably because they usually have comorbidities. Among them, the metabolic syndrome is a major risk factor for DPN. The pathophysiology of DPN is complex, but mechanisms converge on a unifying theme of bioenergetic failure in the peripheral nerves due to their unique anatomy. Current clinical management focuses on controlling diabetes, the metabolic syndrome, and pain, but remains suboptimal for most patients. Thus, research is ongoing to improve early diagnosis and prognosis, to identify molecular mechanisms that could lead to therapeutic targets, and to investigate lifestyle interventions to improve clinical outcomes.

Contribution of hyperglycemia-induced changes in microglia to Alzheimer's disease pathology

Alzheimer's disease (AD) is a neurodegenerative condition characterized by cognitive and functional impairments. The investigation of AD has focused on the formation of senile plaques, composed mainly by amyloid β (Aβ) peptide, and neurofibrillary tangles (NFTs) in the brain. Senile plaques and NFTs cause the excessive recruitment and activation of microglia, thus generating neuroinflammation and neuronal damage. Among the risk factors for the development of AD, diabetes has increasingly attracted attention. Hyperglycemia, the fundamental characteristic of diabetes, is involved in several mechanisms that give rise to microglial overactivation, resulting in neuronal damage and cognitive impairment. Indeed, various studies have identified the correlation between diabetes and AD. The aim of this review is to describe various mechanisms of the hyperglycemia-induced overactivation of microglia, which leads to neuroinflammation and neuronal damage and consequently contributes to the pathology of AD. The disruption of the regulation of microglial activity by hyperglycemia occurs through many mechanisms, including a greater production of reactive oxygen species (ROS) and glycation end products (AGEs), and a decrease in the elimination of Aβ. The future direction of research on the relation between hyperglycemia and AD is addressed, such as the importance of determining whether the hyperglycemia-induced harmful effects on microglial activity can be reversed or attenuated if blood glucose returns to a normal level.

Berberine protects against palmitate induced beta cell injury via promoting mitophagy

BACKGROUND

Destruction of pancreatic beta cells is the most typical characteristic of diabetes.

OBJECTIVE

We aimed to evaluate the effect of berberine (BBR), a bioactive isoquinoline derivative alkaloid, on beta cell injury.

METHODS

Rodent pancreatic beta cell line INS-1 was treated with 0.5 mM palmitate (PA) for 24 h to establish an in vitro beta cell injury model.

RESULTS

BBR at 5 µM promoted cell viability, inhibited cell apoptosis and enhanced insulin secretion in PA-induced INS-1 cells. BBR treatment also suppressed PA-induced oxidative stress in INS-1 cells, as evidenced by the decreased ROS production and increased activities of antioxidant enzymes. In addition, suppressed ATP production and reduced mitochondrial membrane potential were restored by BBR in PA-treated INS-1 cells. It was further determined that BBR affected the expressions of mitophagy-associated proteins, suggesting that BBR promoted mitophagy in PA-exposed INS-1 cells. Meanwhile, we found that BBR facilitated nuclear expression and DNA-binding activity of Nrf2, an antioxidative protein that can regulate mitophagy. Finally, a rescue experiment was performed and the results demonstrated that the effect of BBR on cell viability, apoptosis and mitochondrial function in PA-induced INS-1 cells were cancelled by PINK1 knockdown.

CONCLUSIONS

BBR protects islet β cells from PA-induced injury, and this protective effect may be achieved by regulating mitophagy. The present study may provide a novel therapeutic strategy for β cell injury in diabetes mellitus.

mTOR Signalling Pathway: A Potential Therapeutic Target for Ocular Neurodegenerative Diseases

Recent advances in the research of the mammalian target of the rapamycin (mTOR) signalling pathway demonstrated that mTOR is a robust therapeutic target for ocular degenerative diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma. Although the exact mechanisms of individual ocular degenerative diseases are unclear, they share several common pathological processes, increased and prolonged oxidative stress in particular, which leads to functional and morphological impairment in photoreceptors, retinal ganglion cells (RGCs), or retinal pigment epithelium (RPE). mTOR not only modulates oxidative stress but is also affected by reactive oxygen species (ROS) activation. It is essential to understand the complicated relationship between the mTOR pathway and oxidative stress before its application in the treatment of retinal degeneration. Indeed, the substantial role of mTOR-mediated autophagy in the pathogenies of ocular degenerative diseases should be noted. In reviewing the latest studies, this article summarised the application of rapamycin, an mTOR signalling pathway inhibitor, in different retinal disease models, providing insight into the mechanism of rapamycin in the treatment of retinal neurodegeneration under oxidative stress. Besides basic research, this review also summarised and updated the results of the latest clinical trials of rapamycin in ocular neurodegenerative diseases. In combining the current basic and clinical research results, we provided a more complete picture of mTOR as a potential therapeutic target for ocular neurodegenerative diseases.

Oxidative stress in the pathophysiology of type 2 diabetes and related complications: Current therapeutics strategies and future perspectives

Type 2 diabetes (T2DM) is a persistent metabolic disorder rising rapidly worldwide. It is characterized by pancreatic insulin resistance and β-cell dysfunction. Hyperglycemia induced reactive oxygen species (ROS) production and oxidative stress are correlated with the pathogenesis and progression of this metabolic disease. To counteract the harmful effects of ROS, endogenous antioxidants of the body or exogenous antioxidants neutralise it and maintain bodily homeostasis. Under hyperglycemic conditions, the imbalance between the cellular antioxidant system and ROS production results in oxidative stress, which subsequently results in the development of diabetes. These ROS are produced in the endoplasmic reticulum, phagocytic cells and peroxisomes, with the mitochondrial electron transport chain (ETC) playing a pivotal role. The exacerbated ROS production can directly cause structural and functional modifications in proteins, lipids and nucleic acids. It also modulates several intracellular signaling pathways that lead to insulin resistance and impairment of β-cell function. In addition, the hyperglycemia-induced ROS production contributes to micro- and macro-vascular diabetic complications. Various in-vivo and in-vitro studies have demonstrated the anti-oxidative effects of natural products and their derived bioactive compounds. However, there is conflicting clinical evidence on the beneficial effects of these antioxidant therapies in diabetes prevention. This review article focused on the multifaceted role of oxidative stress caused by ROS overproduction in diabetes and related complications and possible antioxidative therapeutic strategies targeting ROS in this disease.

Docosahexaenoic Acid Suppresses Oxidative Stress-Induced Autophagy and Cell Death via the AMPK-Dependent Signaling Pathway in Immortalized Fischer Rat Schwann Cells 1

Autophagy is the process by which intracellular components are degraded by lysosomes. It is also activated by oxidative stress; hence, autophagy is thought to be closely related to oxidative stress, one of the major causes of diabetic neuropathy. We previously reported that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) induced antioxidant enzymes and protected Schwann cells from oxidative stress. However, the relationship between autophagy and oxidative stress-induced cell death in diabetic neuropathy has not been elucidated. Treatment with tert-butyl hydroperoxide (tBHP) decreased the cell survival rate, as measured by an MTT assay in immortalized Fischer rat Schwann cells 1 (IFRS1). A DHA pretreatment significantly prevented tBHP-induced cytotoxicity. tBHP increased autophagy, which was revealed by the ratio of the initiation markers, AMP-activated protein kinase, and UNC51-like kinase phosphorylation. Conversely, the DHA pretreatment suppressed excessive tBHP-induced autophagy signaling. Autophagosomes induced by tBHP in IFRS1 cells were decreased to control levels by the DHA pretreatment whereas autolysosomes were only partially decreased. These results suggest that DHA attenuated excessive autophagy induced by oxidative stress in Schwann cells and may be useful to prevent or reduce cell death in vitro. However, its potentiality to treat diabetic neuropathy must be validated in in vivo studies.

Liraglutide preserves CD34+ stem cells from dysfunction Induced by high glucose exposure

Background

Glucagon like peptide-1 receptor agonists (GLP-1RAs) have shown to reduce mortality and cardiovascular events in patients with type 2 diabetes mellitus (T2DM). Since the impairment in number and function of vasculotrophic circulating CD34⁺ hematopoietic stem progenitor cells (HSPCs) in T2D has been reported to increase cardiovascular (CV) risk, we hypothesized that one of the mechanisms whereby GLP-1 RAs exert CV protective effects may be related to the ability to improve CD34⁺ HSPC function.

Methods

In cord blood (CB)-derived CD34⁺ HSPC, the expression of GLP-1 receptor (GLP-1R) mRNA, receptor protein and intracellular signaling was evaluated by RT-qPCR and Western Blot respectively. CD34⁺ HSPCs were exposed to high glucose (HG) condition and GLP-1RA liraglutide (LIRA) was added before as well as after functional impairment. Proliferation, CXCR4/SDF-1α axis activity and intracellular ROS production of CD34⁺ HSPC were evaluated.

Results

CD34⁺ HSPCs express GLP-1R at transcriptional and protein level. LIRA treatment prevented and rescued HSPC proliferation, CXCR4/SDF-1α axis activity and metabolic imbalance from HG-induced impairment. LIRA stimulation promoted intracellular cAMP accumulation as well as ERK1/2 and AKT signaling activation. The selective GLP-1R antagonist exendin (9–39) abrogated LIRA-dependent ERK1/2 and AKT phosphorylation along with the related protective effects.

Conclusion

We provided the first evidence that CD34⁺ HSPC express GLP-1R and that LIRA can favorably impact on cell dysfunction due to HG exposure. These findings open new perspectives on the favorable CV effects of GLP-1 RAs in T2DM patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01486-9.

Adaptation to oxidative stress at cellular and tissue level

Several in vitro and in vivo investigations have already proved that cells and tissues, when pre-exposed to low oxidative stress by different stimuli such as chemical, physical agents and environmental factors, display more resistance against subsequent stronger ischaemic injuries, resulting in an adaptive response known as ischaemic preconditioning (IPC). The aim of this review is to report the most recent knowledge about the complex adaptive mechanisms, including signalling transduction pathways, antioxidant systems, apoptotic and inflammation pathways, underlying cell protection against oxidative damage. In addition, an update about in vivo adaptation strategies in response to ischaemic/reperfusion episodes and brain trauma is also given.

An Insight into Potential Pharmacotherapeutic Agents for Painful Diabetic Neuropathy

Diabetes is the 4th most common disease affecting the world's population. It is accompanied by many complications that deteriorate the quality of life. Painful diabetic neuropathy (PDN) is one of the debilitating consequences of diabetes that effects one-third of diabetic patients. Unfortunately, there is no internationally recommended drug that directly hinders the pathological mechanisms that result in painful diabetic neuropathy. Clinical studies have shown that anticonvulsant and antidepressant therapies have proven fruitful in management of pain associated with PDN. Currently, the FDA approved medications for painful diabetic neuropathies include duloxetine, pregabalin, tapentadol extended release, and capsaicin (for foot PDN only). The FDA has also approved the use of spinal cord stimulation system for the treatment of diabetic neuropathy pain. The drugs recommended by other regulatory bodies include gabapentin, amitriptyline, dextromethorphan, tramadol, venlafaxine, sodium valproate, and 5 % lidocaine patch. These drugs are only partially effective and have adverse effects associated with their use. Treating painful symptoms in diabetic patient can be frustrating not only for the patients but also for health care workers, so additional clinical trials for novel and conventional treatments are required to devise more effective treatment for PDN with minimal side effects. This review gives an insight on the pathways involved in the pathogenesis of PDN and the potential pharmacotherapeutic agents. This will be followed by an overview on the FDA-approved drugs for PDN and commercially available topical analgesic and their effects on painful diabetic neuropathies.

Attenuation of Oxidative Stress-Induced Cell Apoptosis and Pyroptosis in RSC96 Cells by Salvianolic Acid B

OBJECTIVE

To determine whether salvianolic acid B (Sal B) exerts protective effects on diabetic peripheral neuropathy by attenuating apoptosis and pyroptosis.

METHODS

RSC96 cells were primarily cultured with DMEM (5.6 mmol/L glucose), hyperglycemia (HG, 125 mmol/L glucose) and Sal B (0.1, 1, and 10 µ mol/L). Cells proliferation was measured by 3-(4, 5-cimethylthiazol-2-yl)-2, 5-dilphenyltetrazolium bromide assay. Reactive oxygen species (ROS) generation and apoptosis rate were detected by flow cytometry analysis. Western blot was performed to analyze the expressions of poly ADP-ribose polymerase (PARP), cleaved-caspase 3, cleaved-caspase 9, Bcl-2, Bax, NLRP3, ASC, and interleukin (IL)-1 β.

RESULTS

Treatment with HG at a concentration of 125 mmol/L attenuated cellular proliferation, while Sal B alleviated this injury (P<0.05). In addition, Sal B inhibited HG-induced ROS production and apoptosis rate (P<0.05). Furthermore, treatment with Sal B down-regulated HG-induced PARP, cleaved-caspase 3, cleaved-caspase 9, Bax, NLRP3, ASC, and IL-1 β expression, but mitigated HG-mediated down-regulation of Bcl-2 expression (P<0.05).

CONCLUSION

Sal B may protect RSC96 cells against HG-induced cellular injury via the inhibition of apoptosis and pyroptosis activated by ROS.

Effect of caffeine on the possible amelioration of diabetic neuropathy: A spectroscopic study

IMPORTANCE

One of the consequential and alarming complications of diabetes mellitus is diabetic neuropathy (DN). DN is assured to be caused chiefly by excess sorbitol levels in the body. The harmful consequences of DN alike peripheral nerve damage with extremity ulcers may be dodged with timely detection and treatment. The therapeutic methods for DN are scarce and expensive. Therefore economic and user friendly methodologies to prevent acquiring the disease need proper attention.

OBJECTIVE

The present research has been conducted (1) to analyse the levels of sorbitol in diabetic blood samples and compare them with non-diabetic ones and (2) to study the reduction in sorbitol levels upon addition of an important biochemical compounds caffeine in both sample groups.

RESEARCH DESIGN, SETTING, PARTICIPANTS AND METHOD

Sorbitol-caffeine interaction analysis of blood samples of 16 patients with type 2 diabetes from KPC Medical College, Kolkata, India was made. The spectroscopic analysis and their interpretations were compared with 16 healthy subjects.

MAIN OUTCOMES AND MEASURES

Present work describes that caffeine can be helpful in reducing the sorbitol level in diabetics, so the chances of development and progression of diabetic neuropathy can be controlled with the introduction of caffeine.

RESULTS

A total number of 32 blood samples of patients (aged 35-70 years); mean age ranges were 52.06 ± 2.68 and 53.50 ± 2.66 years for non-diabetic and diabetic ones respectively, glucose and sorbitol screening examination were done by enzymatic methodologies where concentrations were assessed by means of either absorption or fluorescence spectroscopy. The calibration range was 18.2-1119.3 mg/dL (Linear regression analysis r² = 0.996). The sensitivity of this screening program in detecting DN with the healthy adults has been inquired and found efficient. Results of fasting insulin analyses have also been analysed for HOMA-IR (homeostasis model assessment - insulin resistance) and HOMA-B (homeostasis model assessment - pancreatic β cell function) values. Statistical significance of the results in non-diabetic and diabetic groups were performed and found to be statistically significant.

CONCLUSIONS

We have defined the relationship between blood glucose level, insulin level, sorbitol and caffeine in human body and utilized them in the plausible remediation of DN.

Association Between Serum Albumin Levels and Diabetic Peripheral Neuropathy Among Patients with Type 2 Diabetes: Effect Modification of Body Mass Index

BACKGROUND

The role of serum albumin in the risk of diabetic peripheral neuropathy (DPN) remains unclear. This study aimed to explore the relationship between serum albumin level and DPN, and to examine any possible effect modifiers among patients with type 2 diabetes mellitus.

METHODS

This cross-sectional study was conducted in Jiangxi, China, from May 2012 to December 2014. Serum albumin levels were determined in 523 subjects, and the association between serum albumin level and DPN was evaluated using linear regression models (odds ratio [OR] and corresponding 95% confidence interval [CI]).

RESULTS

There was a significant inverse association between serum albumin level (per 1 g/L increment, OR 0.95 [95% CI 0.92-0.98]) and the risk of DPN. Accordingly, when serum albumin was assessed as quartiles, a significantly lower risk of DPN was found in participants in quartile 4 (OR 0.49 [95% CI 0.25-0.95]), compared with those in quartile 1. Consistently, higher albumin levels (≥35 g/L) were associated with decreased odds for DPN (OR 0.36 [95% CI 0.17-0.74]) compared with lower levels. Furthermore, the albumin-DPN association was significantly stronger in patients with a relatively high body mass index (BMI; ≥24 kg/m²; OR 0.91 [95% CI 0.85-0.98]) than in those with a low BMI (<24 kg/m²; OR 0.99 [95% CI 0.94-1.04]; P for interaction = 0.042).

CONCLUSION

These data suggest that serum albumin level could be a novel risk factor for DPN among patients with type 2 diabetes and relatively high BMI (>24 kg/m²).

Large-leaf yellow tea attenuates high glucose-induced vascular endothelial cells injury by up-regulating autophagy and down-regulating oxidative stress

Vascular endothelial cells injury induced by high glucose (HG) plays an important role in the occurrence and development of diabetic vascular complications. Yellow tea has a protective effect on vascular...

Lycorine improves peripheral nerve function by promoting Schwann cell autophagy via AMPK pathway activation and MMP9 downregulation in diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes mellitus and no effective therapy is approved. Here, lycorine, a natural alkaloid, was identified as a potential drug for DPN by the bioinformatics analysis of GEO datasets and Connectivity Map database. Lycorine administration improved peripheral nerve function and autophagy-associated proteins of diabetic mice. Again, in vitro high glucose-cultured rat Schwann cells (RSC96) showed enhanced autophagosome marker LC3-II with the treatment of lycorine. Additionally, beclin-1 and Atg3 were decreased in high glucose-stimulated RSC96 cells, which were reversed by lycorine treatment. Furthermore, DPN-associated differentially expressed genes (DEGs) from GEO datasets and lycorine-drug targets from PubChem and PharmMapper were visually analyzed and revealed that MMP9 was both DPN-associated DEGs and lycorine-drug target. Functional enrichment analysis of MMP9-relevant genes showed that cell energy metabolism was involved. Moreover, lycorine reduced high glucose-enhanced MMP9 expression in RSC96 cells. Overexpression of MMP9 attenuated lycorine-induced the expression of beclin-1, Atg3 and LC3-II in high glucose-cultured RSC96 cells. In addition, AMPK pathway activation was confirmed in lycorine-treated high glucose-cultured RSC96 cells. Then AMPK pathway inhibition attenuated lycorine-reduced MMP9 expression in high glucose-treated RSC96 cells. Molecular docking analysis revealed that lycorine bound the domain of AMPK containing Thr 172 site, which affected AMPK (Thr 172) phosphorylation. Finally, AMPK pathway activation and MMP9 downregulation were also revealed in the sciatic nerves of diabetic mice administrated with lycorine. Taken together, lycorine was advised to promote Schwann cell autophagy via AMPK pathway activation and MMP9 downregulation-induced LC3-II transformation in diabetic peripheral neuropathy.

Quality Control Mechanisms of Mitochondria: Another Important Target for Treatment of Peripheral Neuropathy

Mitochondria provide energy for various cellular activities and are involved in the regulating of several physiological and pathological processes. Mitochondria constitute a dynamic network regulated by numerous quality control mechanisms; for example, division is necessary for mitochondria to develop, and fusion dilutes toxins produced by the mitochondria. Mitophagy removes damaged mitochondria. The etiologies of peripheral neuropathy include congenital and acquired diseases, and the pathogenesis varies; however, oxidative stress caused by mitochondrial damage is the accepted pathogenesis of peripheral neuropathy. Regulation and control of mitochondrial quality might point the way toward potential treatments for peripheral neuropathy. This article will review mitochondrial quality control mechanisms, their involvement in peripheral nerve diseases, and their potential therapeutic role.

Association Between Severe Chronic Obstructive Pulmonary Disease and Polyneuropathy

BACKGROUND Chronic obstructive pulmonary disease (COPD) is a life-threatening and devastating disease associated with low-grade systemic inflammation. In adults, the most common disease of the peripheral nervous system is peripheral neuropathy. While most polyneuropathy has a mixed presentation, some cases are motor dominant and others are sensory dominant. We investigated polyneuropathy in patients with COPD and hypothesized that low-grade systemic inflammation and other pathologies in patients with COPD cause peripheral axonal polyneuropathy. MATERIAL AND METHODS We included 62 patients with COPD without any neurological signs or symptoms, and 30 healthy volunteers with no known neurological or pulmonary diseases as controls. There were 38 men in the COPD group and 17 men in the control group; the mean ages of the 2 groups were 64.88 and 62.7 years, respectively. According to the Global Initiative for Chronic Obstructive Lung Disease COPD report, all COPD patients were group D. After collecting demographic and clinical characteristics of the participants, we performed an electrophysiological examination to investigate polyneuropathy and pulmonary function test results. C-reactive protein, hemoglobin, creatinine, partial carbon dioxide pressure (pCO₂) levels were recorded. Electrophysiological examination was performed with a Medelec Synergy device using standard neurographic procedures, and the results were assessed. RESULTS Significant differences were found for forced expiratory volume in 1 sec (FEV1), %FEV1, forced vital capacity (FVC), %FVC, pCO₂, and hemoglobin and creatinine levels, but all participants had a creatinine level within the normal range. There was no difference in sensory neuropathy between the groups, but a significant difference was found in terms of motor neuropathy. CONCLUSIONS As noted in previous studies, systemic inflammation, increased oxidative stress, decreased oxygen pressure, and multiple comorbidities in patients with COPD may all contribute to the development of neuropathy.

The association of elevated serum lipocalin 2 levels with diabetic peripheral neuropathy in type 2 diabetes

A variety of studies have demonstrated the role of lipocalin 2 (LCN2) in both diabetes and neurological disorders. Nevertheless, the relationship between LCN2 and diabetic peripheral neuropathy (DPN) needs to be elucidated in humans. Therefore, this study aimed to investigate the association of LCN2 with DPN in type 2 diabetes (T2D). A total of 207 participants with T2D and 40 participants with normal glucose tolerance (NGT) were included in this study. All participants were classified into DPN group and non-DPN (NDPN) group based on the Toronto Clinical Neuropathy Scoring (TCNS). Demographic and biochemical parameters were measured. Serum LCN2 levels were determined using an ELISA technique. Serum LCN2 levels in NGT group were lower than those in either DPN group (P = 0.000) or NDPN group (P = 0.043), while serum LCN2 levels in DPN group were higher than NDPN group (P = 0.001). Moreover, serum LCN2 levels positively correlated to TCNS scores, which reflects neuropathy severity (r = 0.438, P = 0.000). Multivariate stepwise regression analysis showed that BMI, triglycerides, and diastolic pressure were independently associated with serum LCN2 in DPN. Additionally, logistic regression analysis demonstrated that LCN2 (odds ratio (OR) = 1.009) and diabetes duration (OR = 1.058) were independently associated with the occurrence of DPN in T2D. Our report reveals the association of serum LCN2 with DPN in T2D. LCN2 might be used to evaluate DPN severity and serve a role in the pathogenesis of DPN.

Loganin Ameliorates Painful Diabetic Neuropathy by Modulating Oxidative Stress, Inflammation and Insulin Sensitivity in Streptozotocin-Nicotinamide-Induced Diabetic Rats

Loganin is an iridoid glycoside with antioxidant, anti-inflammatory, glucose-lowering activities which may address the pathological mechanisms of painful diabetic neuropathy (PDN) related to inflammation, oxidative stress, and hyperglycemia. This study investigated the underlying mechanisms of action of loganin on PDN. The in vivo model of PDN was established by streptozotocin-nicotinamide (STZ-NA) induction in Sprague Dawley (SD) rats. Subsequently, loganin (5 mg/kg) was administered by daily intraperitoneal injection. High-glucose stimulated human SH-SY5Y cells co-incubated with loganin were used to mimic the in vitro model of PDN. Loganin improved PDN rats' associated pain behaviors (allodynia and hyperalgesia), insulin resistance index (HOMA-IR), and serum levels of superoxide dismutase (SOD), catalase and glutathione. Loganin also reduced pain-associated channel protein CaV3.2 and calcitonin gene-related peptide (CGRP) in the surficial spinal dorsal horn of PDN rats. Loganin inhibited oxidative stress and NF-κB activation and decreased the levels of mRNA and protein of proinflammatory factors IL-1β and TNF-α. Moreover, loganin attenuated insulin resistance by modulating the JNK-IRS-1 (insulin receptor substrate-1)-Akt-GSK3β signaling pathway in PDN rats. These results suggested that loganin improved PDN-mediated pain behaviors by inhibiting oxidative stress-provoked inflammation in the spinal cord, resulting in improved neuropathic pain.

Verbascoside Protects Gingival Cells against High Glucose-Induced Oxidative Stress via PKC/HMGB1/RAGE/NFκB Pathway

Impaired wound healing often occurs in patients with diabetes and causes great inconvenience to them. Aside from the presence of prolonged inflammation, the accumulation of oxidative stress is also implicated in the delayed wound healing. In the present study, we tested the effect of verbascoside, a caffeoyl phenylethanoid glycoside, on the improvement of cell viability and wound healing capacity of gingival epithelial cells under high glucose condition. We showed that verbascoside attenuated the high glucose-induced cytotoxicity and impaired healing, which may be associated with the downregulation of oxidative stress. Our results demonstrated that verbascoside increased the activity of the antioxidant enzyme SOD and reduced the oxidative stress indicator, 8-OHdG, as well as apoptosis. Moreover, verbascoside upregulated the PGC1-α and NRF1 expression and promoted mitochondrial biogenesis, which was mediated by suppression of PKC/HMGB1/RAGE/NFκB signaling. Likewise, we showed the inhibitory effect of verbascoside on oxidative stress was via repression of PKC/HMGB1/RAGE/NFκB activation. Also, our data suggested that the PKC-mediated oxidative stress may lead to the elevated production of inflammatory cytokines, IL-6 and IL-1β. Collectively, we demonstrated that verbascoside may be beneficial to ameliorate impaired oral wound healing for diabetic patients.

Recent Insights into the Nutritional Antioxidant Therapy in Prevention and Treatment of Diabetic Vascular Complications - A comprehensive Review

Diabetes mellitus (DM) and DM-induced vascular complications are a significant global healthcare problem causing a decrease in patient quality of life. The main reason for the disability and mortality of patients is rapidly progressing micro- and macroangiopathies. Currently, free radical oxidation is recognized as one of the main mechanisms in the development of DM and associated complications. Under normal physiological conditions, the level of free radicals and antioxidant defense capabilities is balanced. However, imbalance occurs between the antioxidant defense system and pro-oxidants during chronic hyperglycemia and may invoke formation of excess free radicals, leading to activation of lipid peroxidation and accumulation of highly toxic products of free radical oxidation. This is accompanied by varying degrees of insulin deficiency and insulin resistance in DM patients. Simultaneously with the activation of free radical generation, a decrease in the activity of antioxidant defense factors (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, vitamins C and E) and an acceleration of diabetic complications is seen. Therefore, we hypothesize that antioxidants may play a positive role in the treatment of DM patients to prevent DM-induced vascular complications. However this has not been sufficiently studied. In this review, we discuss recent insights into the potential underlying mechanisms of oxidative stress induced diabetic complications, and implications of antioxidants in mitigation of DM-induced vascular complications.

Oxidative Stress: Pathogenetic Role in Diabetes Mellitus and Its Complications and Therapeutic Approaches to Correction

The review presents modern views about the role of oxidative stress reactions in the pathogenesis of types 1 and 2 diabetes mellitus and their complications based on the analysis of experimental and clinical studies. The sources of increased ROS generation in diabetes are specified, including the main pathways of altered glucose metabolism, oxidative damage to pancreatic β-cells, and endothelial dysfunction. The relationship between oxidative stress, carbonyl stress, and inflammation is described. The significance of oxidative stress reactions associated with hyperglycemia is considered in the context of the “metabolic memory” phenomenon. The results of our studies demonstrated significant ethnic and age-related variability of the LPO—antioxidant defense system parameters in patients with diabetes mellitus, which should be considered during complex therapy of the disease. Numerous studies of the effectiveness of antioxidants in diabetes mellitus of both types convincingly proved that antioxidants should be a part of the therapeutic process. Modern therapeutic strategies in the treatment of diabetes mellitus are aimed at developing new methods of personalized antioxidant therapy, including ROS sources targeting combined with new ways of antioxidant delivery.

Calycosin-loaded nanoliposomes as potential nanoplatforms for treatment of diabetic nephropathy through regulation of mitochondrial respiratory function

BACKGROUNDS

One of the most common complications in diabetic nephropathy is generation of high levels of ROS which can be regulated by herbal antioxidants. However, polyphenols like calycosin, the bioactive compound of Radix astragali suffer from low solubility and poor bioavailability.

METHODS

Therefore, in the present study, calycosin-loaded nanoliposomes were fabricated and characterized by TEM, DLS and FTIR techniques. Afterwards, the drug loading (DL) and entrapment efficiency (EE), drug release, solubility, stability, and pharmacodynamic assays were performed. Finally, the antinephropathic effects of calycosin-loaded-nanoliposomes on mitochondria of kidney cells were explored by MTT, ROS, MDA, mitochondrial respiratory function assays.

RESULTS

The result showed that the size, hydrodynamic radius, zeta potential, EE, and DL were, 80 nm, 133.99 ± 21.44 nm, - 20.53 ± 3.57, 88.37 ± 2.28%, and 7.48 ± 1.19%, respectively. The outcomes of in vitro release assay showed that calycosin-loaded nanoliposomes were significantly slow-release in dialysis media with pH 1.2, pH 6.9 and pH 7.4, at about 30 min, the dissolution of calycosin from nanoliposome became almost complete, and after 2 months, the calycosin-loaded nanoliposomes were still stable. Pharmacokinetic assay revealed that the AUC0-t of calycosin in calycosin-loaded nanoliposome group was 927.39 ± 124.91 μg/L*h, which was 2.26 times than that of the free calycosin group (**P < 0.01). Additionally, the MRT0-t and t1/2 of calycosin in the calycosin-loaded nanoliposome group were prolonged by 1.54 times and 1.33 times than that of free calycosin group, respectively (*P < 0.05). Finally, it was shown that calycosin-loaded nanoliposomes regulated the viability, ROS production, lipid peroxidation and function of mitochondria in kidney cells of diabetic rats as a model of diabetic nephropathy.

CONCLUSION

In conclusion it may be suggested that new therapies based on nano-formulated calycosin can restore mitochondrial function which can improve diabetic nephropathy.

Ammonium Glycyrrhizinate Prevents Apoptosis and Mitochondrial Dysfunction Induced by High Glucose in SH-SY5Y Cell Line and Counteracts Neuropathic Pain in Streptozotocin-Induced Diabetic Mice

Glycyrrhiza glabra, commonly known as liquorice, contains several bioactive compounds such as flavonoids, sterols, triterpene, and saponins; among which, glycyrrhizic acid, an oleanane-type saponin, is the most abundant component in liquorice root. Diabetic peripheral neuropathy is one of the major complications of diabetes mellitus, leading to painful condition as neuropathic pain. The pathogenetic mechanism of diabetic peripheral neuropathy is very complex, and its understanding could lead to a more suitable therapeutic strategy. In this work, we analyzed the effects of ammonium glycyrrhizinate, a derivate salt of glycyrrhizic acid, on an in vitro system, neuroblastoma cells line SH-SY5Y, and we observed that ammonium glycyrrhizinate was able to prevent cytotoxic effect and mitochondrial fragmentation after high-glucose administration. In an in vivo experiment, we found that a short-repeated treatment with ammonium glycyrrhizinate was able to attenuate neuropathic hyperalgesia in streptozotocin-induced diabetic mice. In conclusion, our results showed that ammonium glycyrrhizinate could ameliorate diabetic peripheral neuropathy, counteracting both in vitro and in vivo effects induced by high glucose, and might represent a complementary medicine for the clinical management of diabetic peripheral neuropathy.

Ethoxyquin is neuroprotective and partially prevents somatic and autonomic neuropathy in db/db mouse model of type 2 diabetes

Ethoxyquin (EQ), a quinolone-based antioxidant, has demonstrated neuroprotective properties against several neurotoxic drugs in a phenotypic screening and is shown to protect axons in animal models of chemotherapy-induced peripheral neuropathy. We assessed the effects of EQ on peripheral nerve function in the db/db mouse model of type II diabetes. After a 7 week treatment period, 12-week-old db/db-vehicle, db/+ -vehicle and db/db-EQ treated animals were evaluated by nerve conduction, paw withdrawal against a hotplate, and fiber density in hindlimb footpads. We found that the EQ group had shorter paw withdrawal latency compared to vehicle db/db group. The EQ group scored higher in nerve conduction studies, compared to vehicle-treated db/db group. Morphology studies yielded similar results. To investigate the potential role of mitochondrial DNA (mtDNA) deletions in the observed effects of EQ, we measured total mtDNA deletion burden in the distal sciatic nerve. We observed an increase in total mtDNA deletion burden in vehicle-treated db/db mice compared to db/+ mice that was partially prevented in db/db-EQ treated animals. These results suggest that EQ treatment may exert a neuroprotective effect in diabetic neuropathy. The prevention of diabetes-induced mtDNA deletions may be a potential mechanism of the neuroprotective effects of EQ in diabetic neuropathy.

Mitochondrial remodelling-a vicious cycle in diabetic complications

Diabetes mellitus (DM) is a chronic, metabolic condition characterized by excessive blood glucose that causes perturbations in physiological functioning of almost all the organs of human body. This devastating metabolic disease has its implications in cognitive decline, heart damage, renal, retinal and neuronal complications that severely affects quality of life and associated with decreased life expectancy. Mitochondria possess adaptive mechanisms to meet the cellular energy demand and combat cellular stress. In recent years mitochondrial homeostasis has been point of focus where several mechanisms regulating mitochondrial health and function are evaluated. Mitochondrial dynamics plays crucial role in maintaining healthy mitochondria in cell under physiological as well as stress condition. Mitochondrial dynamics and corresponding regulating mechanisms have been implicated in progression of metabolic disorders including diabetes and its complications. In current review we have discussed about role of mitochondrial dynamics under physiological and pathological conditions. Also, modulation of mitochondrial fission and fusion in diabetic complications are described. The available literature supports mitochondrial remodelling as reliable target for diabetic complications.

Genetic and Epigenomic Modifiers of Diabetic Neuropathy

Diabetic neuropathy (DN), the most common chronic and progressive complication of diabetes mellitus (DM), strongly affects patients’ quality of life. DN could be present as peripheral, autonomous or, clinically also relevant, uremic neuropathy. The etiopathogenesis of DN is multifactorial, and genetic components play a role both in its occurrence and clinical course. A number of gene polymorphisms in candidate genes have been assessed as susceptibility factors for DN, and most of them are linked to mechanisms such as reactive oxygen species production, neurovascular impairments and modified protein glycosylation, as well as immunomodulation and inflammation. Different epigenomic mechanisms such as DNA methylation, histone modifications and non-coding RNA action have been studied in DN, which also underline the importance of “metabolic memory” in DN appearance and progression. In this review, we summarize most of the relevant data in the field of genetics and epigenomics of DN, hoping they will become significant for diagnosis, therapy and prevention of DN.

Impact of COVID-19 Pandemic on the Implantation of Intra-Cardiac Devices in Diabetic and Non-Diabetic Patients in the Western of Romania

Background and Objectives: COVID-19 pandemic severely impacted public health services worldwide, determining a significant decrease of elective cardiovascular (CV) procedures, especially in patients with associated chronic diseases such as diabetes mellitus (DM). Materials and Methods: This study was first started in 2019 in the western of Romania, to analyze the differences regarding the implantations of intra-cardiac devices such as permanent pacemakers (PPM), cardiac resynchronization therapy (CRT), or implantable cardioverter-defibrillators (ICD) in 351 patients with and without DM and the situation was reanalyzed at the end of 2020. Results: of the first 351 patients with and without DM. 28.20% of these patients had type 2 DM (p = 0.022), exceeding more than twice the prevalence of DM in the general population (11%). Patients with DM were younger (p = 0.022) and required twice as often CRT (p = 0.002) as non-diabetic patients. The state of these procedures was reanalyzed at the end of 2020, a dramatic decrease of all new device implantations being observed, both in non-diabetic and in patients with type 2 DM (79.37%, respectively 81.82%). Conclusions: COVID-19 pandemic determined a drastic decrease, with around 75% reduction of all procedures of new intra-cardiac devices implantation, both in non-diabetics, this activity being reserved mostly for emergencies.

Exploration of the hepatoprotective effect and mechanism of magnesium isoglycyrrhizinate in mice with arsenic trioxide‑induced acute liver injury

Arsenic trioxide (ATO)-induced hepatotoxicity limits the therapeutic effect of acute myelogenous leukemia treatment. Magnesium isoglycyrrhizinate (MgIG) is a natural compound extracted from licorice and a hepatoprotective drug used in liver injury. It exhibits anti-oxidant, anti-inflammatory and anti-apoptotic properties. The aim of the present study was to identify the protective action and underlying mechanism of MgIG against ATO-induced hepatotoxicity. A total of 50 mice were randomly divided into five groups (n=10/group): Control; ATO; MgIG and high- and low-dose MgIG + ATO. Following continuous administration of ATO for 7 days, the relative weight of the liver, liver enzyme, histological data, antioxidant enzymes, pro-inflammatory cytokines, cell apoptosis and changes in Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) signaling pathway were observed. MgIG decreased liver injury, decreased the liver weight and liver index, inhibited oxidative stress and decreased the activity of glutathione, superoxide dismutase and catalase, production of reactive oxygen species and levels of pro-inflammatory cytokines, including IL-1β, IL-6 and TNF-α. Western blotting showed a decrease in Bax and caspase-3. There was decreased cleaved caspase-3 expression and increased Bcl-2 expression. MgIG notably activated ATO-mediated expression of Keap1 and Nrf2 in liver tissue. MgIG administration was an effective treatment to protect the liver from ATO-induced toxicity. MgIG maintained the level of Nrf2 in the liver and protected the antioxidative defense system to attenuate oxidative stress and prevent ATO-induced liver injury.

Sarcopenia in Chronic Kidney Disease: Focus on Advanced Glycation End Products as Mediators and Markers of Oxidative Stress

Sarcopenia is common in chronic kidney disease (CKD), and it is independently associated with morbidity and mortality. Advanced glycation end products (AGE) are mainly known as aging products. In CKD, AGE accumulate due to increased production and reduced kidney excretion. The imbalance between oxidant/antioxidant capacities in CKD patients is one of the main factors leading to AGE synthesis. AGE can, in turn, promote CKD progression and CKD-related complications by increasing reactive oxygen species generation, inducing inflammation, and promoting fibrosis. All these derangements can further increase AGE and uremic toxin accumulation and promote loss of muscle mass and function. Since the link between AGE and sarcopenia in CKD is far from being fully understood, we revised hereby the data supporting the potential contribution of AGE as mediators of oxidative stress in the pathogenesis of sarcopenia. Understanding how AGE and oxidative stress impact the onset of sarcopenia in CKD may help to identify new potential markers of disease progression and/or therapeutic targets.