Modulation of redox and insulin signaling underlie the anti-hyperglycemic and antioxidant effects of diphenyl diselenide in zebrafish

Depolymerization of oyster glycosaminoglycans for the enhancement of α-glucosidase inhibition and its application in hypoglycemic studies

Glycosaminoglycans are a class of naturally occurring macromolecular heteropolysaccharides with α-glucosidase inhibitory effects, which play an essential role in regulating postprandial hyperglycemia. However, the significant molecular weight hinders their inhibitory activity. In this study, oyster glycosaminoglycans were used for purification and depolymerization studies to obtain oyster glycosaminoglycan oligosaccharides (OGAG-Oli) and to study their inhibitory activity against α-glucosidase in vitro and hypoglycemic effect on hyperglycemic zebrafish in vivo. The results showed that the OGAG-Oli with optimal α-glucosidase inhibition obtained by the β-elimination mechanism of chondroitinase ABC had a molecular weight of about 2400 Da with five disaccharide repeating units, and their inhibitory effect on α-glucosidase was significantly enhanced with an IC50 value of 0.12 mg/mL, which was related to the strong binding capacity with α-glucosidase as evidenced by molecular docking. FT-IR and NMR results showed that the conformation of OGAG-Oli was predominantly in the α-configuration, which indicated that its inhibitory effect on α-glucosidase mainly depended on the α-glucosidic bond therein. The enzymatic depolymerization process of glycosaminoglycans was optimized, and the process conditions were determined as phosphate buffer solution pH 8.0, reaction time 3 h, reaction temperature 30 °C, chondroitin enzyme ABC activity 0.5 mU. The hypoglycemic ability of OGAG-Oli was evaluated in diabetic zebrafish, and the results showed that OGAG-Oli at a high-dose (0.12 mg/g, bw/d) could extremely significantly reduce fasting blood glucose in zebrafish, with an effect close to that of acarbose (p > 0.05), and exceptionally significantly (p < 0.01) reduced the elevation of TC, TG, and LDL-C caused by prolonged hyperglycemia, and extremely significantly (p < 0.01) increased the HDL-C level. This study showed that the structurally modified oyster glycosaminoglycans had intense α-glucosidase inhibitory activity, and exhibited biological activity of reducing glucose uptake and consequently improving body weight and lipid metabolism in diabetic zebrafish. As a bioactive ingredient of natural origin, this study provides a theoretical basis for the development and utilization of glycosaminoglycans with hypoglycemic effects in foods and drugs.

Diphenyl diselenide protects against diabetic kidney disease through modulating gut microbiota dysbiosis in streptozotocin-induced diabetic rats

Introduction

Diphenyl diselenide (DPDS) ameliorates nephropathy in streptozotocin (STZ)-induced type 1 diabetic rats by inhibiting oxidative stress and inflammatory reactions. However, it has not been clarified whether DPDS alleviates type 1 diabetic kidney disease (DKD) is related to the inhibition of extracellular matrix (ECM) production and the regulation of intestinal flora disorder.

Methods

The present study investigated the effects of DPDS on ECM generation in the kidney and intestinal microflora composition in feces. The rats were orally administered DPDS or metformin for eight weeks. Various indices were measured to assess the severity of renal injury. After euthanizing the rats, oxidative stress markers in serum and kidney were assessed using biochemical methods, and the expressions of ECM-related proteins in kidney were analyzed using Western blot. Additionally, 16S rRNA high-throughput sequencing was used to evaluate the diversity and composition of the intestinal flora in feces.

Results

The results showed DPDS and metformin improved the DKD in STZ rats, as evidenced by decreased blood glucose, BUN, urine volume, urine microalbumin, urinary β2 microglobulin, and improvement of renal pathological morphology. Furthermore, DPDS intervention markedly reduced the protein expression of α-SMA, COI Ⅳ, FN, and vimentin in the kidneys. Besides, DPDS not only improved dyslipidemia in STZ diabetic rats, but also enhanced the activities of antioxidant enzymes, decreased the level of MDA in serum and kidney, and regulated the expression of proteins related to the Nrf2/Keap1 signaling pathway in the kidney. Moreover, we found that DPDS could selectively improve the relative abundance of probiotics as well as the diversity of flora, thus ameliorating the intestinal microbial composition of the STZ rats, significantly regulating the intestinal microbial homeostasis.

Discussion

Overall, DPDS inhibited ECM production and improved renal pathological changes, which may be related to reducing oxidative stress damage in the kidney and improving intestinal flora imbalance, providing data support for the further development and application of DPDS in DKD.

Negative impacts of social isolation on behavior and neuronal functions are recovered after short-term social reintroduction in zebrafish

Recently, social isolation measures were crucial to prevent the spread of the coronavirus pandemic. However, the lack of social interactions affected the population mental health and may have long-term consequences on behavior and brain functions. Here, we evaluated the behavioral, physiological, and molecular effects of a social isolation (SI) in adult zebrafish, and whether the animals recover such changes after their reintroduction to the social environment. Fish were submitted to 12 days of SI, and then reintroduced to social context (SR). Behavioral analyses to evaluate locomotion, anxiety-like and social-related behaviors were performed after SI protocol, and 3 and 6 days after SR. Cortisol and transcript levels from genes involved in neuronal homeostasis (c-fos, egr, bdnf), and serotonergic (5-HT) and dopaminergic (DA) neurotransmission (thp, th) were also measured. SI altered social behaviors in zebrafish such as aggression, social preference, and shoaling. Fish submitted to SI also presented changes in the transcript levels of genes related to neural activity, and 5-HT/DA signaling. Interestingly, most of the behavioral and molecular changes induced by SI were not found again 6 days after SR. Thus, we highlight that SR of zebrafish to their conspecifics played a positive role in social behaviors and in the expression of genes involved in different neuronal signaling pathways that were altered after 12 days of SI. This study brings unprecedented data on the effects of SR in the recovery from SI neurobehavioral alterations, and reinforces the role of zebrafish as a translational model for understanding the neurobiological mechanisms adjacent to SI and resocialization.

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides

Diorganyl diselenides have emerged as privileged structures because they are easy to prepare, have distinct reactivity, and have broad biological activity. They have also been used in the synthesis of natural products as an electrophile in the organoselenylation of aromatic systems and peptides, reductions of alkenes, and nucleophilic substitution. This review summarizes the advancements in methods for the transformations promoted by diorganyl diselenides in the main functions of organic chemistry. Parallel, it will also describe the main findings on pharmacology and toxicology of diorganyl diselenides, emphasizing anti-inflammatory, hypoglycemic, chemotherapeutic, and antimicrobial activities. Therefore, an examination detailing the reactivity and biological characteristics of diorganyl diselenides provides valuable insights for academic researchers and industrial professionals.

Biofiltering capacity of Chambardia rubens (Bivalvia: Unionidae) may modulate expression of stress and growth genes inhibited by the neonicotinoid insecticide acetamiprid in zebrafish

Neonicotinoid insecticides specifically target insect subtypes of nicotinic acetylcholine receptors. Acetamiprid (ACE: C10H11ClN4), the neonicotinoid insecticide, is used to control crop insect pests worldwide. It is a nitrile, monochloropyridine, and carboxamidine that is highly soluble and accessible to waterways. There, it causes neurotoxic and oxidative perturbance to non-target organisms. The unionid mussel Chamabradia rubens is a common Northern River Nile suspension feeder. The current study aimed to assess ACE filtration from waters by C. rubens, and whether this biological power can reduce ACE effects on fish. Removal of ACE by C. rubens was assessed using LC-MS/MS. Zebrafish Danio rerio adults were exposed to different sublethal doses of ACE in the presence or absence of C. rubens in their aquaria. The results showed that mussels could remove significant ACE amounts from water, where it accumulated mostly in the digestive gland. The presence of C.rubens in zebrafish aquaria having ACE was accompanied by significant upregulation of antioxidant enzyme gene transcripts and total H2O2 scavenging, in contrast to mussel-free ACE-exposed groups. Meanwhile, liver triglycerides rose 5-6-fold in response to ACE in the "Fish-Only" groups, indicating an ACE-induced hepatotoxicity. Also, Insulin-like growth factor 1 (igf1) and fish body mass increased more in "Fish + Mussel" groups than in the "Fish-Only" ones. In aggregate, these findings suggest that the Nile mussel could reduce the oxidative stress and metabolic changes induced in fish by ACE. This can contribute valuable environmental and economic benefits upon the use of this mussel as a biofilter.

Disease-modifying potential of diphenyl diselenide in an experimental osteoarthritis model

Oxidative stress is a key factor in the disruption of cartilage homeostasis during the development of osteoarthritis (OA). Organic selenium (Se)-containing compounds such as diselenides have excellent antioxidant activity and may prevent related diseases. We aimed to examine the benefits of the synthetic small molecule diphenyl diselenide (DPDSe) in OA models in vitro and in vivo. Our findings showed that DPDSe could maintain extracellular matrix (ECM) homeostasis and inhibit reactive oxygen species (ROS) production in IL-1β-treated chondrocytes. In a destabilization of the medial meniscus (DMM)-induced OA mouse model, intra-articular administration of DPDSe alleviated joint degeneration, as evidenced by a decrease in the OARSI score and the restoration of collagen II (COL2) and MMP-13 expression in cartilage tissues. We confirmed that DDS activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in IL-1β-treated chondrocytes, and its chondroprotective effects were significantly counteracted when Nrf2 signaling was blocked by the inhibitor ML385 or by siRNA-mediated Nrf2 knockdown. The relatively strong performance of DPDSe makes it an ideal candidate for further trials as a disease-modifying OA drug (DMOAD).

The beneficial and toxic effects of selenium on zebrafish. A systematic review of the literature

Selenium is an important and essential trace element in organisms, but its effects on organisms are also a "double-edged sword". Selenium deficiency or excess can endanger the health of humans and animals. In order to thoroughly understand the nutritional value and toxicity hazards of selenium, researchers have conducted many studies on the model animal zebrafish. However, there is a lack of induction and summary of relevant research on which selenium acts on zebrafish. This paper provides a review of the reported studies. Firstly, this article summarizes the benefits of selenium on zebrafish from three aspects: Promoting growth, Enhancing immune function and anti-tumor ability, Antagonizing some pollutants, such as mercury. Then, three aspects of selenium toxicity to zebrafish are introduced: nervous system and behavior, reproductive system and growth, and damage to some organs. This article also describes how different forms of selenium compounds have different effects on zebrafish health. Finally, prospects for future research directions are presented.

Diphenyl Diselenide Through Reduction of Inflammation, Oxidative Injury and Caspase-3 Activation Abates Doxorubicin-Induced Neurotoxicity in Rats

Neurotoxicity associated with chemotherapy is a debilitating side effect of cancer management in humans which reportedly involves inflammatory and oxidative stress responses. Diphenyl diselenide (DPDS) is an organoselenium compound which exhibits its anti-tumoral, anti-oxidant, anti-inflammatory and anti-mutagenic effects. Nevertheless, its possible effect on chemotherapy-induced neurotoxicity is not known. Using rat model, we probed the behavioral and biochemical effects accompanying administration of antineoplastic agent doxorubicin (7.5 mg/kg) and DPDS (5 and 10 mg/kg). Anxiogenic-like behavior, motor and locomotor insufficiencies associated with doxorubicin were considerably abated by both DPDS doses with concomitant enhancement in exploratory behavior as demonstrated by reduced heat maps intensity and enhanced track plot densities. Moreover, with exception of cerebral glutathione (GSH) level, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, biochemical data demonstrated reversal of doxorubicin-mediated decline in cerebral and cerebellar antioxidant status indices and the increase in acetylcholinesterase (AChE) activity by both doses of DPDS. Also, cerebellar and cerebral lipid peroxidation, hydrogen peroxide as well as reactive oxygen and nitrogen species levels were considerably diminished in rats administered doxorubicin and DPDS. In addition, DPDS administration abated myeloperoxidase activity, tumour necrosis factor alpha and nitric oxide levels along with caspase-3 activity in doxorubicin-administered rats. Chemoprotection of doxorubicin-associated neurotoxicity by DPDS was further validated by histomorphometry and histochemical staining. Taken together, DPDS through offsetting of oxido-inflammatory stress and caspase-3 activation elicited neuroprotection in doxorubicin-treated rats.

Diphenyl Diselenide Attenuates Mitochondrial Damage During Initial Hypoxia and Enhances Resistance to Recurrent Hypoxia

Hypoxia plays a significant role in the development of various cerebral diseases, many of which are associated with the potential risk of recurrence due to mitochondrial damage. Conventional drug treatments are not always effective for hypoxia-related brain diseases, necessitating the exploration of alternative compounds. In this study, we investigated the potential of diphenyl diselenide [(PhSe)2] to ameliorate locomotor impairments and mitigate brain mitochondrial dysfunction in zebrafish subjected to hypoxia. Additionally, we explored whether these improvements could confer resistance to recurrent hypoxia. Through a screening process, an appropriate dose of (PhSe)2 was determined, and animals exposed to hypoxia received a single intraperitoneal injection of 100 mg/kg of the compound or vehicle. After 1 h from the injection, evaluations were conducted on locomotor deficits, (PhSe)2 content, mitochondrial electron transport system, and mitochondrial viability in the brain. The animals were subsequently exposed to recurrent hypoxia to assess the latency time to hypoxia symptoms. The findings revealed that (PhSe)2 effectively crossed the blood-brain barrier, attenuated locomotor deficits induced by hypoxia, and improved brain mitochondrial respiration by modulating complex III. Furthermore, it enhanced mitochondrial viability in the telencephalon, contributing to greater resistance to recurrent hypoxia. These results demonstrate the beneficial effects of (PhSe)2 on both hypoxia and recurrent hypoxia, with cerebral mitochondria being a critical target of its action. Considering the involvement of brain hypoxia in numerous pathologies, (PhSe)2 should be further tested to determine its effectiveness as a potential treatment for hypoxia-related brain diseases.

Anthropogenic underwater noise: A review on physiological and molecular responses of marine biota

The detrimental effects of anthropogenic underwater noise on marine organisms have garnered significant attention among scientists. This review delves into the research concerning the repercussions of underwater noise on marine species, with specific emphasis on the physiological and molecular responses of marine biota. This review investigates the sensory mechanisms, hearing sensitivity, and reaction thresholds of diverse marine organisms, shedding light on their susceptibility to underwater noise disturbances. The physiological and molecular effects of anthropogenic underwater noise on marine biota include oxidative stress, energy homeostasis, metabolism, immune function, and respiration. Additionally, changes in the gene expression profile associated with oxidative stress, metabolism, and immunological response are among the responses reported for marine biota. These effects pose a threat to animal fitness and potentially affect their survival as individuals and populations.

Insulin signaling promotes neurogenesis in the brain of adult zebrafish

Insulin is a peptide hormone that plays a central role in the regulation of circulating blood glucose in vertebrates, including zebrafish. Increasing evidence has demonstrated the important role of insulin in many brain functions. In zebrafish, two insulin receptor genes (insra and insrb) have been identified. However, their biodistribution in the adult brain as well as their cell-specific expression pattern has not been well described. Using gene expression analysis, in situ hybridization and transgenic fish, we confirmed the expression of insra, insrb, and irs1 (insulin receptor substrate 1, the downstream effector of insulin receptor) in the brain of adult zebrafish and characterized their specific expression in neurons and neural stem cells (radial glia). After demonstrating that intracerebroventricular (ICV) injection resulted in the diffusion of the injected solution within the ventricular system, we analyzed the effect of insulin ICV injection on neurogenesis. We showed that insulin promotes ventricular cell proliferation 24 h postinjection. This neurogenic effect appeared to be independent of neuroinflammatory processes. Also, after a mechanical telencephalic stab-wound injury, we highlighted the overexpression of irs1 gene 5 days postlesion notably in the ventricular zone where radial glial cells (RGCs) are localized, suggesting key roles of insulin signaling in regenerative processes. Finally, our results reinforced the expression of insulin-related proteins in the brain of adult zebrafish, highlighting the potential role of insulin signaling on neurogenesis.

Recent Advances in the Synthesis and Antioxidant Activity of Low Molecular Mass Organoselenium Molecules

Selenium is an essential trace element in living organisms, and is present in selenoenzymes with antioxidant activity, like glutathione peroxidase (GPx) and thioredoxin reductase (TrxR). The search for small selenium-containing molecules that mimic selenoenzymes is a strong field of research in organic and medicinal chemistry. In this review, we review the synthesis and bioassays of new and known organoselenium compounds with antioxidant activity, covering the last five years. A detailed description of the synthetic procedures and the performed in vitro and in vivo bioassays is presented, highlighting the most active compounds in each series.

Ebselen and Diphenyl Diselenide Inhibit SARS-CoV-2 Replication at Non-Toxic Concentrations to Human Cell Lines

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the causative agent of the COVID-19 pandemic, a global public health problem. Despite the numerous studies for drug repurposing, there are only two FDA-approved antiviral agents (Remdesivir and Nirmatrelvir) for non-hospitalized patients with mild-to-moderate COVID-19 symptoms. Consequently, it is pivotal to search for new molecules with anti-SARS-CoV-2 activity and to study their effects in the human immune system. Ebselen (Eb) is an organoselenium compound that is safe for humans and has antioxidant, anti-inflammatory, and antimicrobial properties. Diphenyl diselenide ((PhSe)₂) shares several pharmacological properties with Eb and is of low toxicity to mammals. Herein, we investigated Eb and (PhSe)₂ anti-SARS-CoV-2 activity in a human pneumocytes cell model (Calu-3) and analyzed their toxic effects on human peripheral blood mononuclear cells (PBMCs). Both compounds significantly inhibited the SARS-CoV-2 replication in Calu-3 cells. The EC₅₀ values for Eb and (PhSe)₂ after 24 h post-infection (hpi) were 3.8 µM and 3.9 µM, respectively, and after 48 hpi were 2.6 µM and 3.4 µM. These concentrations are safe for non-infected cells, since the CC₅₀ values found for Eb and (PhSe)₂ on Calu-3 were greater than 200 µM. Importantly, the concentration rates tested on viral replication were not toxic to human PBMCs. Therefore, our findings reinforce the efficacy of Eb and demonstrate (PhSe)₂ as a new candidate to be tested in future trials against SARS-CoV-2 infection/inflammation conditions.

Zebrafish: A New Promise to Study the Impact of Metabolic Disorders on the Brain

Zebrafish has become a popular model to study many physiological and pathophysiological processes in humans. In recent years, it has rapidly emerged in the study of metabolic disorders, namely, obesity and diabetes, as the regulatory mechanisms and metabolic pathways of glucose and lipid homeostasis are highly conserved between fish and mammals. Zebrafish is also widely used in the field of neurosciences to study brain plasticity and regenerative mechanisms due to the high maintenance and activity of neural stem cells during adulthood. Recently, a large body of evidence has established that metabolic disorders can alter brain homeostasis, leading to neuro-inflammation and oxidative stress and causing decreased neurogenesis. To date, these pathological metabolic conditions are also risk factors for the development of cognitive dysfunctions and neurodegenerative diseases. In this review, we first aim to describe the main metabolic models established in zebrafish to demonstrate their similarities with their respective mammalian/human counterparts. Then, in the second part, we report the impact of metabolic disorders (obesity and diabetes) on brain homeostasis with a particular focus on the blood-brain barrier, neuro-inflammation, oxidative stress, cognitive functions and brain plasticity. Finally, we propose interesting signaling pathways and regulatory mechanisms to be explored in order to better understand how metabolic disorders can negatively impact neural stem cell activity.

Targeting NRF2 in Type 2 diabetes mellitus and depression: Efficacy of natural and synthetic compounds

Evidence supports a strong bidirectional association between depression and Type 2 diabetes mellitus (T2DM). The harmful impact of oxidative stress and chronic inflammation on the development of both disorders is widely accepted. Nuclear factor erythroid 2-related factor 2 (NRF2) is a pertinent target in disease management owing to its reputation as the master regulator of antioxidant responses. NRF2 influences the expression of various cytoprotective phase 2 antioxidant genes, which is hampered in both depression and T2DM. Through interaction and crosstalk with several signaling pathways, NRF2 endeavors to contain the widespread oxidative damage and persistent inflammation involved in the pathophysiology of depression and T2DM. NRF2 promotes the neuroprotective and insulin-sensitizing properties of its upstream and downstream targets, thereby interrupting and preventing disease advancement. Standard antidepressant and antidiabetic drugs may be powerful against these disorders, but unfortunately, they come bearing distressing side effects. Therefore, exploiting the therapeutic potential of NRF2 activators presents an exciting opportunity to manage such bidirectional and comorbid conditions.

Recent development in zebrafish model for bioactivity and safety evaluation of natural products

The zebrafish is a species of freshwater fish, popular in aquariums and laboratories. Several advantageous features have facilitated zebrafish to be extensively utilized as a valuable vertebrate model in the lab. It has been well-recognized that natural products possess multiple health benefits for humans. With the increasing demand for natural products in the development of functional foods, nutraceuticals, and natural cosmetics, the zebrafish has emerged as an unprecedented tool for rapidly and economically screening and identifying safe and effective substances from natural products. This review first summarized the key factors for the management of zebrafish in the laboratory, followed by highlighting the current progress on the establishment and applications of zebrafish models in the bioactivity evaluation of natural products. In addition, the zebrafish models used for assessing the potential toxicity or health risks of natural products were involved as well. Overall, this review indicates that zebrafish are promising animal models for the bioactivity and safety evaluation of natural products, and zebrafish models can accelerate the discovery of novel natural products with potential health functions.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Diphenyl diselenide ameliorates diabetic nephropathy in streptozotocin-induced diabetic rats via suppressing oxidative stress and inflammation

Oxidative stress and inflammation are implicated in the occurrence and progression of diabetic nephropathy (DN). Diphenyl diselenide (DPDS) is a stable and simple diaryl diselenide with anti-hyperglycemic, anti-inflammatory, and antioxidant activities. However, the effects of DPDS on DN are still unclear to date. Herein, we aimed to explore whether DPDS could improve renal dysfunction in streptozotocin (STZ)-induced diabetic rats and its underlying mechanisms. STZ-induced DN rats were administered with DPDS (5 or 15 mg/kg) or metformin (200 mg/kg) once daily by intragastric gavage for 12 weeks. DPDS supplementation significantly improved hyperglycemia, glucose intolerance, dyslipidemia, and the renal pathological abnormalities, concurrent with significantly reduced serum levels of creatinine, urea nitrogen, urine volume, and urinary levels of micro-albumin, β2-microglobulin and N-acetyl-glucosaminidase activities. Moreover, DPDS effectively promoted the activities of antioxidant enzymes, and reduced the levels of MDA and pro-inflammatory factors in serum and the kidney. Furthermore, DPDS supplementation activated the renal Nrf2/Keap1 signaling pathway, but attenuated the high phosphorylation levels of NFκB, JNK, p38 and ERK1/2. Altogether, the current study indicated for the first time that DPDS ameliorated STZ-induced renal dysfunction in rats, and its mechanism of action may be attributable to suppressing oxidative stress via activating the renal Nrf2/Keap1 signaling pathway and mitigating inflammation by suppressing the renal NFκB/MAPK signaling pathways, suggesting a potential therapeutic approach for DN.