Dietary fish oil inhibits mechanical allodynia and thermal hyperalgesia in diabetic rats by blocking nuclear factor-κB-mediated inflammatory pathways

Metabolomic profiling of pediatric post-tonsillectomy pain: A proof-of-concept study

INTRODUCTION

Tonsillectomies are among the most common surgical procedures in children, with over 500 000 cases annually in the United States. Despite universal administration of intraoperative opioid analgesia, three out of five children undergoing tonsillectomy report moderate-to-severe pain upon recovering from anesthesia. The underlying molecular mechanisms of post-tonsillectomy pain are not well understood, limiting the development of targeted treatment strategies. Our study aimed to identify candidate serum metabolites associated with varying severity of post-tonsillectomy pain.

METHODS

Venous blood samples and pain scores were obtained from 34 children undergoing tonsillectomy ± adenoidectomy, and metabolomic analysis was performed. Supervised orthogonal projections to latent structures discriminant analysis were employed to identify differentially expressed metabolites between children with severe and mild pain, as well as between moderate and mild pain.

RESULTS

Pain scores differentiated children as mild (n = 6), moderate (n = 14), or severe (n = 14). Four metabolites (fatty acid 18:0(OH), thyroxine, phosphatidylcholine 38:5, and branched fatty acids C27H54O3) were identified as candidate biomarkers that differentiated severe vs. mild post-tonsillectomy pain, the combination of which yielded an AUC of 0.91. Similarly, four metabolites (sebacic acid, dicarboxylic acids C18H34O4, hydroxy fatty acids C18H34O3, and myristoleic acid) were identified as candidate biomarkers that differentiated moderate vs. mild post-tonsillectomy pain, with AUC values ranging from 0.85 to 0.95.

CONCLUSION

This study identified novel candidate biomarker panels that effectively differentiated varying severity of post-tonsillectomy pain. Further research is needed to validate these data and to explore their clinical implications for personalized pain management in children undergoing painful surgeries.

Characteristics of glucolipid metabolism and complications in novel cluster-based diabetes subgroups: a retrospective study

BACKGROUND

Glucolipid metabolism plays an important role in the occurrence and development of diabetes mellitus. However, there is limited research on the characteristics of glucolipid metabolism and complications in different subgroups of newly diagnosed diabetes. This study aimed to investigate the characteristics of glucolipid metabolism and complications in novel cluster-based diabetes subgroups and explore the contributions of different glucolipid metabolism indicators to the occurrence of complications and pancreatic function.

METHODS

This retrospective study included 547 newly diagnosed type 2 diabetes patients. Age, body mass index (BMI), glycated hemoglobin (HbA1C), homeostasis model assessment-2 beta-cell function (HOMA2-β), and homeostasis model assessment-2 insulin resistance (HOMA2-IR) were used as clustering variables. The participants were divided into 4 groups by k-means cluster analysis. The characteristics of glucolipid indicators and complications in each subgroup were analyzed. Regression analyses were used to evaluate the impact of glucolipid metabolism indicators on complications and pancreatic function.

RESULTS

Total cholesterol (TC), triglycerides (TG), triglyceride glucose index (TyG), HbA1C, fasting plasma glucose (FPG), and 2-h postprandial plasma glucose (2hPG) were higher in the severe insulin-resistant diabetes (SIRD) and severe insulin-deficient diabetes (SIDD) groups. Fasting insulin (FINS), fasting C-peptide (FCP), 2-h postprandial insulin (2hINS), 2-h postprandial C-peptide (2hCP), and the monocyte-to-high-density lipoprotein cholesterol ratio (MHR) were higher in mild obesity-related diabetes (MOD) and SIRD. 2hCP, FCP, and FINS were positively correlated with HOMA2-β, while FPG, TyG, HbA1C, and TG were negatively correlated with HOMA2-β. FINS, FPG, FCP, and HbA1C were positively correlated with HOMA2-IR, while high-density lipoprotein (HDL) was negatively correlated with HOMA2-IR. FINS (odds ratio (OR),1.043;95% confidence interval (CI) 1.006 ~ 1.081), FCP (OR,2.881;95%CI 2.041 ~ 4.066), and TyG (OR,1.649;95%CI 1.292 ~ 2.104) contributed to increase the risk of nonalcoholic fatty liver disease (NAFLD); 2hINS (OR,1.015;95%CI 1.008 ~ 1.022) contributed to increase the risk of atherosclerotic cardiovascular disease (ASCVD); FCP (OR,1.297;95%CI 1.027 ~ 1.637) significantly increased the risk of chronic kidney disease (CKD).

CONCLUSIONS

There were differences in the characteristics of glucolipid metabolism as well as complications among different subgroups of newly diagnosed type 2 diabetes. 2hCP, FCP, FINS, FPG, TyG, HbA1C, HDL and TG influenced the function of insulin. FINS, TyG, 2hINS, and FCP were associated with ASCVD, NAFLD, and CKD in newly diagnosed T2DM patients.

Omega-3 polyunsaturated fatty acids and corneal nerve health: Current evidence and future directions

Corneal nerves play a key role in maintaining ocular surface integrity. Corneal nerve damage, from local or systemic conditions, can lead to ocular discomfort, pain, and, if poorly managed, neurotrophic keratopathy. Omega-3 polyunsaturated fatty acids (PUFAs) are essential dietary components that play a key role in neural development, maintenance, and function. Their potential application in modulating ocular and systemic inflammation has been widely reported. Omega-3 PUFAs and their metabolites also have neuroprotective properties and can confer benefit in neurodegenerative disease. Several preclinical studies have shown that topical administration of omega-3 PUFA-derived lipid mediators promote corneal nerve recovery following corneal surgery. Dietary omega-3 PUFA supplementation can also reduce corneal epithelial nerve loss and promote corneal nerve regeneration in diabetes. Omega-3 PUFAs and their lipid mediators thus show promise as therapeutic approaches to modulate corneal nerve health in ocular and systemic disease. This review discusses the role of dietary omega-3 PUFAs in maintaining ocular surface health and summarizes the possible applications of omega-3 PUFAs in the management of ocular and systemic conditions that cause corneal nerve damage. In examining the current evidence, this review also highlights relatively underexplored applications of omega-3 PUFAs in conferring neuroprotection and addresses their therapeutic potential in mediating corneal nerve regeneration.

Treatment for Diabetic Peripheral Neuropathy: What have we Learned from Animal Models?

INTRODUCTION

Animal models have been widely used to investigate the etiology and potential treatments for diabetic peripheral neuropathy. What we have learned from these studies and the extent to which this information has been adapted for the human condition will be the subject of this review article.

METHODS

A comprehensive search of the PubMed database was performed, and relevant articles on the topic were included in this review.

RESULTS

Extensive study of diabetic animal models has shown that the etiology of diabetic peripheral neuropathy is complex, with multiple mechanisms affecting neurons, Schwann cells, and the microvasculature, which contribute to the phenotypic nature of this most common complication of diabetes. Moreover, animal studies have demonstrated that the mechanisms related to peripheral neuropathy occurring in type 1 and type 2 diabetes are likely different, with hyperglycemia being the primary factor for neuropathology in type 1 diabetes, which contributes to a lesser extent in type 2 diabetes, whereas insulin resistance, hyperlipidemia, and other factors may have a greater role. Two of the earliest mechanisms described from animal studies as a cause for diabetic peripheral neuropathy were the activation of the aldose reductase pathway and increased non-enzymatic glycation. However, continuing research has identified numerous other potential factors that may contribute to diabetic peripheral neuropathy, including oxidative and inflammatory stress, dysregulation of protein kinase C and hexosamine pathways, and decreased neurotrophic support. In addition, recent studies have demonstrated that peripheral neuropathy-like symptoms are present in animal models, representing pre-diabetes in the absence of hyperglycemia.

CONCLUSION

This complexity complicates the successful treatment of diabetic peripheral neuropathy, and results in the poor outcome of translating successful treatments from animal studies to human clinical trials.

Atorvastatin prevents the development of diabetic neuropathic nociception by possible involvement of nitrergic system

AIMS

Diabetic neuropathy has been identified as a common complication caused by diabetes. However, its pathophysiological mechanisms are not fully understood yet. Statins, also known as HMG-CoA reductase inhibitors, alleviate the production of cholesterol. Despite this cholesterol-reducing effect of statins, several reports have demonstrated their beneficial properties in neuropathic pain. In this study, we used streptozotocin (STZ)-induced diabetic model to investigate the possible role of nitric oxide (NO) in the antineuropathic-like effect of atorvastatin.

METHODS

Diabetes was induced by a single injection of STZ. Male rats orally received different doses of atorvastatin for 21 days. To access the neuropathy process, the thermal threshold of rats was assessed using hot plate and tail-flick tests. Moreover, sciatic motor nerve conduction velocity (MNCV) studies were performed. To assess the role of nitric oxide, N(G)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine (AG), and 7-nitroindazole (7NI) were intraperitoneally administered along with some specific doses of atorvastatin.

KEY FINDINGS

Atorvastatin significantly reduced the hyperalgesia in diabetic rats. L-NAME pretreatment with atorvastatin showed the antihyperalgesic effect, suggesting the possible involvement of the NO pathway in atorvastatin protective action. Furthermore, co-administration of atorvastatin with AG and 7NI resulted in a significant increase in pain threshold in diabetic rats.

SIGNIFICANCE

Our results reveal that the atorvastatin protective effect on diabetic neuropathy is mediated at least in a part via the nitric oxide system.

Short- and Long-Term Effects of Dietary Supplementation with Fish Oil on Inflammatory Pain in Rats

INTRODUCTION

Dietary supplementation with fish oil is promising as a complementary therapy for inflammatory pain. However, further studies are needed to support its therapeutic potential. For example, the antinociceptive effect of fish oil is widely suggested to be dependent on decreased prostaglandin E₂ (PGE₂) synthesis, but no previous study has investigated if it affects PGE₂-induced nociceptive response. Similarly, beneficial long-term effects on inflammatory response are related to early exposure to fish oil, however, whether these effects include decreased inflammatory pain throughout life is not known.

OBJECTIVE

The aim of this study was to investigate the short- and long-term effects of fish oil on inflammatory pain.

METHODS

Dietary fish oil supplementation was performed through two protocols: in adult rats, during 20 days, or in dams, during pregnancy and lactation, with tests performed in adult offspring. The hyperalgesic response induced by carrageenan and its final mediators PGE₂ and norepinephrine was used to model inflammatory pain.

RESULTS

The findings demonstrated for the first time that dietary fish oil (1) decreases the hyperalgesia induced by carrageenan; (2) but not that induced by its final mediator PGE₂ and norepinephrine; (3) increase omega-3 polyunsaturated fatty acids in peripheral neural tissue; and (4) attenuates inflammatory pain in individuals exposed to fish oil during pre-natal life and lactation.

CONCLUSION

Together, these findings support that fish oil decreases inflammatory pain either when consumed during adult life or during prenatal development. Future studies should confirm the therapeutic potential of fish oil in humans, which is essential for the development of public policies to encourage a fish oil richer diet.

Evolving concepts on the role of dyslipidemia, bioenergetics, and inflammation in the pathogenesis and treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most widespread and disabling neurological conditions, accounting for half of all neuropathy cases worldwide. Despite its high prevalence, no approved disease modifying therapies exist. There is now a growing body of evidence that DPN secondary to type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) represents different disease processes, with T2DM DPN best understood within the context of metabolic syndrome rather than hyperglycemia. In this review, we highlight currently understood mechanisms of DPN, along with their corresponding potential therapeutic targets. We frame this discussion within a practical overview of how the field evolved from initial human observations to murine pathomechanistic and therapeutic models into ongoing and human clinical trials, with particular emphasis on T2DM DPN and metabolic syndrome.

Aging and the immune response in diabetic peripheral neuropathy

A large proportion of older individuals with diabetes go on to develop diabetic peripheral neuropathy (DPN). DPN is associated with an increase in inflammatory cells within the peripheral nerve, activation of nuclear factor kappa-light-chain-enhancer of activated B cells and receptors for advanced glycation end products/advanced glycation end products pathways, aberrant cytokine expression, oxidative stress, ischemia, as well as pro-inflammatory changes in the bone marrow; all processes that may be exacerbated with age. We review the immunological features of DPN and discuss whether age-related changes in relevant immunological areas may contribute to age being a risk factor for DPN.

Specialized pro-resolving mediators in diabetes: novel therapeutic strategies

Diabetes mellitus (DM) is an important metabolic disorder characterized by persistent hyperglycemia resulting from inadequate production and secretion of insulin, impaired insulin action, or a combination of both. Genetic disorders and insulin receptor disorders, environmental factors, lifestyle choices and toxins are key factors that contribute to DM. While it is often referred to as a metabolic disorder, modern lifestyle choices and nutrient excess induce a state of systemic chronic inflammation that results in the increased production and secretion of inflammatory cytokines that contribute to DM. It is chronic hyperglycemia and the low-grade chronic-inflammation that underlies the development of microvascular and macrovascular complications leading to damage in a number of tissues and organs, including eyes, vasculature, heart, nerves, and kidneys. Improvements in the management of risk factors have been beneficial, including focus on intensified glycemic control, but most current approaches only slow disease progression. Even with recent studies employing SGLT2 inhibitors demonstrating protection against cardiovascular and kidney diseases, kidney function continues to decline in people with established diabetic kidney disease (DKD). Despite the many advances and a greatly improved understanding of the pathobiology of diabetes and its complications, there remains a major unmet need for more effective therapeutics to prevent and reverse the chronic complications of diabetes. More recently, there has been growing interest in the use of specialised pro-resolving mediators (SPMs) as an exciting therapeutic strategy to target diabetes and the chronic complications of diabetes.

New insights into the mechanisms of diabetic complications: role of lipids and lipid metabolism

Diabetes adversely affects multiple organs, including the kidney, eye and nerve, leading to diabetic kidney disease, diabetic retinopathy and diabetic neuropathy, respectively. In both type 1 and type 2 diabetes, tissue damage is organ specific and is secondary to a combination of multiple metabolic insults. Hyperglycaemia, dyslipidaemia and hypertension combine with the duration and type of diabetes to define the distinct pathophysiology underlying diabetic kidney disease, diabetic retinopathy and diabetic neuropathy. Only recently have the commonalities and differences in the metabolic basis of these tissue-specific complications, particularly those involving local and systemic lipids, been systematically examined. This review focuses on recent progress made using preclinical models and human-based approaches towards understanding how bioenergetics and metabolomic profiles contribute to diabetic kidney disease, diabetic retinopathy and diabetic neuropathy. This new understanding of the biology of complication-prone tissues highlights the need for organ-specific interventions in the treatment of diabetic complications.

Amelioration of PM2.5-induced lung toxicity in rats by nutritional supplementation with fish oil and Vitamin E

BACKGROUND

Exposure to fine particulate matter (PM_2.5) has been associated with respiratory morbidity and mortality. Identification of interventional measures that are efficacious against PM_2.5-induced toxicity may provide public health benefits. This study examined the inhibitory effects of nutritional supplementation with fish oil as a source of omega-3 fatty acids and vitamin E (Vit E) on PM_2.5-induced lung toxicity in rats.

METHOD

Sixty four male Sprague Dawley rats were gavaged with phosphate buffered saline (PBS), corn oil (5 ml/kg), fish oil (150 mg/kg), or Vit E (75 mg/kg), respectively, once a day for 21 consecutive days prior to intratracheal instillation of PM_2.5 (10 mg/kg) every other day for a total of 3 times. Serum and bronchoalveolar lavage fluids (BALFs) were collected 24 h after the last instillation of PM_2.5. Levels of total proteins (TP), lactate dehydrogenase (LDH), superoxide dismutase (SOD), 8-epi-prostaglandin F2α (8-epi-PGF2α), interleukin-1β (IL-1β), C-reactive protein (CRP), IL-6, and tumor necrosis factor-ɑ (TNF-ɑ) were analyzed for markers of cell injury and inflammation. Additionally, histological alterations of lung tissues were examined by hematoxylin-eosin staining.

RESULT

Exposure to PM_2.5 resulted in lung toxicity, represented as increased levels of total proteins, LDH, 8-epi-PGF2α, IL-1β and TNF-α, and increased infiltration of inflammatory cells, and decreased SOD in the BALFs, and systemic inflammation, as evinced by increased levels of CRP and IL-6 in serum. Strikingly, supplementation with fish oil but not Vit E significantly ameliorated PM_2.5-induced lung toxicity and systemic inflammation.

CONCLUSION

PM_2.5 exposure induces oxidative stress, lung injury and inflammation, which is ameliorated significantly by fish oil and partially by Vit E.

The Potential Role of Fatty Acids in Treating Diabetic Neuropathy

PURPOSE OF REVIEW

This review will summarize recent findings of the effect of supplemental fatty acids, with an emphasis on omega-3 polyunsaturated fatty acids, as a treatment for diabetic peripheral neuropathy.

RECENT FINDINGS

Pre-clinical studies have provided evidence that treating diabetic rodents with δ linolenic acid (omega-6 18:3) and to a greater extent with eicosapentaenoic and docosahexaenoic acids (omega-3 20:5 and 22:6, respectively) improve and even reverse vascular and neural deficits. Additional studies have shown resolvins, metabolites of eicosapentaenoic and docosahexaenoic acids, can induce neurite outgrowth in neuron cultures and that treating type 1 or type 2 diabetic mice with resolvin D1 or E1 provides benefit for peripheral neuropathy similar to fish oil. Omega-3 polyunsaturated fatty acids derived from fish oil and their derivatives have anti-inflammatory properties and could provide benefit for diabetic peripheral neuropathy. However, clinical trials are needed to determine whether this statement is true.

Effect of Fish Oil vs. Resolvin D1, E1, Methyl Esters of Resolvins D1 or D2 on Diabetic Peripheral Neuropathy

Objective

Fish oil is enriched in omega-3 polyunsaturated fatty acids primarily eicosapentaenoic and docosahexaenoic fatty acids. Metabolites of these two polyunsaturated fatty acids include the E and D series resolvins. Omega-3 polyunsaturated fatty acids and resolvins have been reported to have anti-inflammatory and neuroprotective properties. The objective of this study was to evaluate the efficacy of menhaden oil, a fish oil derived from the menhaden, resolvins D1 and E1 and the methyl esters of resolvins D1 and D2 on diabetic peripheral neuropathy. Hypothesis being examined was that the methyl esters of resolvins D1 and D2 would be move efficacious than resolvins D1 or E1 due to an extended half-life.

Methods

A model of type 2 diabetes in C57BL/6J mice was created through a combination of a high fat diet followed 8 weeks later with treatment of low dosage of streptozotocin. After 8 weeks of untreated hyperglycemia type 2 diabetic mice were treated for 8 weeks with menhaden oil in the diet or daily injections of 1 ng/g body weight resolvins D1, E1 or methyl esters of resolvins D1 or D2. Afterwards, multiple neurological endpoints were examined.

Results

Menhaden oil or resolvins did not improve hyperglycemia. Untreated diabetic mice were thermal hypoalgesic, had mechanical allodynia, reduced motor and sensory nerve conduction velocities and decreased innervation of the cornea and skin. These endpoints were significantly improved with menhaden oil or resolvin treatment. However, the methyl esters of resolvins D1 or D2, contrary to our hypothesis, were generally less potent than menhaden oil or resolvins D1 or E1.

Conclusion

These studies further support omega-3 polyunsaturated fatty acids derived from fish oil via in part due to their metabolites could be an effective treatment for diabetic neuropathy.

Long-Chain Omega-3 Fatty Acids Supplementation Accelerates Nerve Regeneration and Prevents Neuropathic Pain Behavior in Mice

Fish oil (FO) is the main source of long chain omega-3 polyunsaturated fatty acids (ω-3 PUFAs), which display relevant analgesic and anti-inflammatory properties. Peripheral nerve injury is driven by degeneration, neuroinflammation, and neuronal plasticity which results in neuropathic pain (NP) symptoms such as allodynia and hyperalgesia. We tested the preventive effect of an EPA/DHA-concentrate fish oil (CFO) on NP development and regenerative features. Swiss mice received daily oral treatment with CFO 4.6 or 2.3 g/kg for 10 days after NP was induced by partial sciatic nerve ligation. Mechanical allodynia and thermal hypernociception were assessed 5 days after injury. CFO 2.3 g/kg significantly prevented mechanical and thermal sensitization, reduced TNF levels in the spinal cord, sciatic MPO activity, and ATF-3 expression on DRG cells. CFO improved Sciatic Functional Index (SFI) as well as electrophysiological recordings, corroborating the increased GAP43 expression and total number of myelinated fibers observed in sciatic nerve. No locomotor activity impairment was observed in CFO treated groups. These results point to the regenerative and possibly protective properties of a combined EPA and DHA oral administration after peripheral nerve injury, as well as its anti-neuroinflammatory activity, evidencing ω-3 PUFAs promising therapeutic outcomes for NP treatment.

Inhibition of NF-κB activity by aminoguanidine alleviates neuroinflammation induced by hyperglycemia

Neuroinflammation is a key feature of cerebral complication which is associated with diabetes mellitus (DM). Inducible nitric oxide synthase (iNOS) is implicated in the pathogenesis of neuroinflammation. However, how iNOS facilitates the development of inflammation in brain is still unidentified. The aim of the present study was to investigate the association of iNOS and neuroinflammation in diabetic mice, and elucidate the potential mechanisms underlying aminoguanidine (AG), the selective inhibitor of iNOS, protected neurons against inflammation in diabetic mice. In present experiment, diabetic mice model were established by a single intraperitoneal injection of streptozotocin (STZ). AG was administered to diabetic mice for ten weeks after this disease induction. Then we measured iNOS activity in the serum and brain, detected the glial fibrillary acidic protein (GFAP) and ionised calcium binding adaptor molecule-1 (Iba-1) expressions in the brain. Moreover, nuclear factor-kappa B (NF-κB) in cytoplasm and nucleus were tested by IP and WB. Results revealed that high expression of iNOS in serum and brain could be reversed by AG treatment. Furthermore, AG could also inhibit GFAP and Iba-1 expressions, and NF-κB nuclear translocation by inhibiting it from binding to iNOS in cytoplasm. Our findings indicated that iNOS can combine with NF-κB in cytoplasm and promote its nuclear transfer in diabetic mice. Furthermore, AG decreased neuroinflammation through inhibiting iNOS activity and reducing NF-κB nuclear translocation by promoting its dissociation with iNOS in cytoplasm.

Epoxy fatty acids mediate analgesia in murine diabetic neuropathy

BACKGROUND

Neuropathic pain is a debilitating condition with no adequate therapy. The health benefits of omega-3 fatty acids are established, however, the role of docosahexaenoic acid (DHA) in limiting pain has only recently been described and the mechanisms of this action remain unknown. DHA is metabolized into epoxydocosapentanoic acids (EDPs) via cytochrome P450 (CYP450) enzymes which are substrates for the soluble epoxide hydrolase (sEH) enzyme. Here, we tested several hypotheses; first, that the antinociceptive action of DHA is mediated by the EDPs. Second, based on evidence that DHA and CYP450 metabolites elicit analgesia through opioid signalling, we investigated this as a possible mechanism of action. Third, we tested whether the analgesia mediated by epoxy fatty acids had similar rewarding effects as opioid analgesics.

METHODS

We tested diabetic neuropathic wild-type and sEH null mice in a conditioned place preference assay for their response to EDPs, sEHI and antagonism of these treatments with naloxone, a mu-opioid receptor antagonist.

RESULTS

The EDPs and sEH inhibitors were efficacious against chronic pain, and naloxone antagonized the action of both EDPs and sEH inhibitors. Despite this antagonism, the sEH inhibitors lacked reward side effects differing from opioids.

CONCLUSIONS

The EpFA are analgesic against chronic pain differing from opioids which have limited efficacy in chronic conditions.

SIGNIFICANCE

EDPs and sEHI mediate analgesia in modelled chronic pain and this analgesia is blocked by naloxone. However, unlike opioids, sEHI are highly effective in neuropathic pain models and importantly lack rewarding side effects.

Docosahexaenoic acid inhibits mechanical allodynia and thermal hyperalgesia in diabetic rats by decreasing the excitability of DRG neurons

Diabetes mellitus is a common metabolic disease in human beings with characteristic symptoms of hyperglycemia, chronic inflammation and insulin resistance. One of the most common complications of early-onset diabetes mellitus is peripheral diabetic neuropathy, which is manifested either by loss of nociception or by allodynia and hyperalgesia. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown the potential of anti-inflammation and modulating neuron excitability. The present study investigated the effects of docosahexaenoic acid (DHA) on the excitability of dorsal root ganglion (DRG) neurons in streptozotocin (STZ)-induced diabetes rats. The effects of DHA on the allodynia and hyperalgesia of diabetic rats were also evaluated. Dietary DHA supplementation effectively attenuated both allodynia and hyperalgesia induced by STZ injection. DHA supplementation decreased the excitability of DRG neurons by decreasing the sodium currents and increasing potassium currents, which may contribute to the effect of alleviating allodynia and hyperalgesia in diabetic rats. The results suggested that DHA might be useful as an adjuvant therapy for the prevention and treatment of painful diabetic neuropathy.