Fish oil supplementation prevents diabetes-induced nerve conduction velocity and neuroanatomical changes in rats

The potential protective effects of melatonin and omega-3 on the male rat optic nerve exposed to 900 MHz electromagnetic radiation during the prenatal period

BACKGROUND

Due to children and adolescents' widespread use of electronic devices, researchers have focused on pre-and early postnatal electromagnetic field (EMF) exposure. However, little is known about the effects of EMF exposure on the optic nerve. The aim of study was to investigate the changes occurring in the optic nerve and the protective effects of melatonin (mel) and omega 3 (ω-3) in rats.

METHODS

Thirty-five pregnant rats were divided into seven groups, Cont, Sham, EMF, EMF + melatonin (EMF + Mel), EMF + ω3, Mel, and ω3. The EMF groups were exposed to 900 megahertz (MHz) EMF daily for two hours during pregnancy. After the experiment, the right optic nerve of each offspring rat was removed and fixed in glutaraldehyde. Thin and semi-thin sections were taken for electron microscopic and stereological analyses. Myelinated axon numbers, myelin sheath thicknesses, and axonal areas were estimated using stereological methods.

RESULTS

The groups had no significant differences regarding mean numbers of axons, mean axonal areas, or mean myelin sheath thicknesses (p > 0.05). Histological observations revealed impaired lamellae in the myelin sheath of most axons, and vacuolization was frequently observed between the myelin sheath and axon in the EMF-exposed group. The Mel and ω-3-treated EMF groups exhibited well-preserved myelinated nerve fibers and intact astrocytes and oligodendrocytes.

CONCLUSIONS

At the ultrastructural level, Mel and ω3 exhibits a neuroprotective effect on the optic nerve exposed to prenatal EMF. The protective effects of these antioxidants on oligodendrocytes, which play an essential role in myelin formation in the central nervous system, now require detailed investigation.

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.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

Omega-3 Nutrition Therapy for the Treatment of Diabetic Sensorimotor Polyneuropathy

Despite advances in clinical and translational research, an effective therapeutic option for diabetic sensorimotor polyneuropathy (DSP) has remained elusive. The pathomechanisms of DSP are diverse, and along with hyperglycemia, the roles of inflammatory mediators and lipotoxicity in the development of microangiopathy have been well elucidated. Omega-3 (n-3) polyunsaturated fatty acids (PUFA) are essential fatty acids with a vital role in a number of physiological processes, including neural health, membrane structure integrity, anti-inflammatory processes, and lipid metabolism. Identification of n-3 PUFA derived specialised proresolving mediators (SPM), namely resolvins, neuroprotectin, and maresins which also favour nerve regeneration, have positioned n-3 PUFA as potential treatment options in DSP. Studies in n-3 PUFA treated animal models of DSP showed positive nerve benefits in functional, electrophysiological, and pathological indices. Clinical trials in humans are limited, but recent proof-of-concept evidence suggests n-3 PUFA has a positive effect on small nerve fibre regeneration with an increase in the small nerve fiber measure of corneal nerve fibre length (CNFL). Further randomized control trials with a longer duration of treatment, higher n-3 PUFA doses, and more rigorous neuropathy measures are needed to provide a definitive understanding of the benefits of n-3 PUFA supplementation in DSP.

N-3 Polyunsaturated Fatty Acids and Their Lipid Mediators as A Potential Immune-Nutritional Intervention: A Molecular and Clinical View in Hepatic Disease and Other Non-Communicable Illnesses

In recent years, the beneficial effect of n-3 polyunsaturated fatty acids (n-3 PUFAs) intake on human health has been widely accepted in the field of immunonutrition. Today, we find a diversity of supplements based on n-3 PUFAs and/or minerals, vitamins and other substances. The main objective of this review is to discuss the importance of n-3 PUFAs and their derivatives on immunity and inflammatory status related to liver disease and other non-communicable illnesses. Based on the burden of liver diseases in 2019, more than two million people die from liver pathologies per year worldwide, because it is the organ most exposed to agents such as viruses, toxins and medications. Consequently, research conducted on n-3 PUFAs for liver disease has been gaining prominence with encouraging results, given that these fatty acids have anti-inflammatory and cytoprotective effects. In addition, it has been described that n-3 PUFAs are converted into a novel species of lipid intermediaries, specialized pro-resolving mediators (SPMs). At specific levels, SPMs improve the termination of inflammation as well as the repairing and regeneration of tissues, but they are deregulated in liver disease. Since evidence is still insufficient to carry out pharmacological trials to benefit the resolution of acute inflammation in non-communicable diseases, there remains a call for continuing preclinical and clinical research to better understand SPM actions and outcomes.

Effect of n-3 polyunsaturated fatty acid supplementation on muscle mass and function with aging: A meta-analysis of randomized controlled trials✰

The results of randomized controlled trials (RCTs) investigating supplemental n-3 polyunsaturated fatty acids (PUFA) on muscle mass and function have been inconsistent. The present study aimed to quantitatively evaluate the effect of n-3 PUFA supplementation on indicators of muscle mass and function in healthy subjects. A systematic literature search was conducted up to July 2020 with databases of PubMed and Web of science. The random-effects model was implemented to calculate the weighted mean difference of net change of indicators regarding muscle mass and function. A total of nine studies (thirteen treatment groups) with 2067 participants were included for data analysis. The summary estimate showed that n-3 PUFA supplementation significantly increased the grip strength (1.17 kg; 95% CI: 0.27, 2.08 kg). Non-significant effect was observed with respect to muscle mass parameters, including fat mass (-0.67 kg; 95% CI: -2.20, 0.87 kg) and lean mass (0.33 kg; 95% CI: -0.35, 1.00 kg). Regarding muscle function indicators, there were non-significant effects on walking speed (-0.01 m•s^-1; 95% CI: -0.03, 0.01 m•s^-1), time up and go test (-0.25 s; 95% CI: -0.55, 0.04 s), respectively. The findings of this study indicated that supplementation with n-3 PUFA might have beneficial effects to improve muscle mass and function in healthy participants. However, there was no significant improvement in the subjects' muscle mass. Whether n-3 PUFA supplementation has favorable effects in participants with sarcopenia are warranted to be further investigated.

Effects of Nonpharmacological Interventions in Chemotherapy-Induced Peripheral Neuropathy: An Overview of Systematic Reviews and Meta-Analyses

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the prevalent and disabling side effects of cancer treatment. However, management strategies for CIPN currently remain elusive, with treatment restricted to neuropathic pain medications, supportive care, and chemotherapy dosing adjustments. This overview explores evidence on the potential benefits and safety of nonpharmacological interventions in preventing and treating CIPN in cancer patients.

METHODS

Seven databases were searched for systematic reviews of randomized controlled trials (RCTs). The methodological quality of the selected reviews was assessed by AMSTAR 2, and the quality of evidence was judged by GRADE. Twenty-eight systematic reviews were considered eligible for this review.

RESULTS

It was found that nonpharmacological interventions (acupuncture, exercise, herbal medicine, nutritional supplements) provided potential benefits for patients with CIPN. Furthermore, Chinese herbal medicine, administered orally or externally, significantly prevented and/or relieved the incidence and severity of CIPN in comparison to control groups (no additional treatment, placebo, and conventional western medicine). However, the quality of evidence and strength of recommendations were compromised by the inconsistencies and imprecision of included studies. The main concerns regarding the quality of systematic reviews included the lack of sufficiently rigorous a priori protocols, and the lack of protocol registration adopted in the included studies.

CONCLUSIONS

Though looking across reviews, Chinese herbal medicine appear generally effective in CIPN, uncertainty remains about the effects of many other nonpharmacological interventions. The evidence on what works was particularly compromised by reporting and methodological limitations, which requires further investigation to be more certain of their effects.

Protective effect of docosahexaenoic acid on lipotoxicity-mediated cell death in Schwann cells: Implication of PI3K/AKT and mTORC2 pathways

BACKGROUND AND AIM

Docosahexaenoic acid (DHA) exhibits neuroprotective properties and has been shown to preserve nerve cells following trauma and ischemic injury. Recently, we showed that DHA pretreatment improved locomotion and reduced neuropathic pain after acute spinal cord injury in adult rats. These improvements were associated with an increase in the levels of AKT in spinal cord injury neurons. In this study, we investigate the implication of PI3K/AKT and mTOR pathway in DHA-mediated protection of primary cultured Schwann cells (pSC) undergoing palmitic acid-induced lipotoxicity (PA-LTx).

METHODS

Primary cultured Schwann cells were treated with PA (PA:BSA, 2:1) in the presence or absence of DHA (1-200 µM) for 24-48 hr. Cell viability was determined by crystal violet staining and nuclear morphology was examined using Hoechst staining.

RESULTS

We found that pSC cultures exposed to palmitic acid (PA) overload showed chromatin condensation, a decrease in cell viability and an inhibition of AKT phosphorylation in a time-dependent manner. Next, pSC exposed to PA overload were treated with DHA. The data show that co-treatment with DHA inhibited the loss of cell viability and apoptosis caused by PA. Moreover, treatment with DHA inhibited chromatin condensation, significantly stimulated p-AKT phosphorylation under PA-LTx condition, and DHA alone increased AKT phosphorylation. Additionally, when these pSC cultures were treated with PI3K inhibitors LY294002 and, BKM120 and mTOR inhibitors Torin 1 (mTORC1/mTORC2), but not rapamycin (mTORC1), the protective effects of DHA were not observed.

CONCLUSION

These findings suggest PI3K/AKT and mTORC2 kinase pathways are involved in the protective function (s) of DHA in PA-induced Schwann cell death.

Comparison of the Effects of Omega 3 and Vitamin E on Palcitaxel-Induced Peripheral Neuropathy

BACKGROUND

Paclitaxel-induced peripheral neuropathy is the most important side effect limiting the use of this medication.

AIM

This study aimed to compare the effects of omega-3 and vitamin E on the incidence of peripheral neuropathy in patients receiving Taxol.

METHODS

In this clinical trial, 63 patients who were a candidate for receiving taxol, were enrolled based on inclusion and exclusion criteria. In group O, patients received 640 mg omega-3 three times a day, and group E, received 300 mg vitamin E two times a day. Patients took the supplements up to three months after the onset of Taxol. Group P received placebo for a similar period. All patients referred to a neurologist for electrophysiological evaluation before the onset of chemotherapy and at months 1 and 3. The presence of neuropathy and its progression was recorded by the neurologist.

RESULTS

Neurological examination in this study indicated that 6 patients (28.6%) in Group O, 7 patients (33.3%) in group E, and 15 patients (71.4%) in placebo group started peripheral neuropathy. There was a significant difference between intervention groups and the placebo group (p = 0.0001) and no significant difference between intervention groups (p = 0.751).

CONCLUSION

Our data suggested that vitamin E and omega-3 may significantly reduce the incidence of Paclitaxel-induced peripheral neuropathy. Routine administration of such supplements that have no special side effect for patients under chemotherapy may greatly enhance their quality of life.

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.

Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) in Muscle Damage and Function

Nutritional supplementation not only helps in improving and maintaining performance in sports and exercise, but also contributes in reducing exercise fatigue and in recovery from exhaustion. Fish oil contains large amounts of omega-3 fatty acids, eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3). It is widely known that omega-3 fatty acids are effective for improving cardiac function, depression, cognitive function, and blood as well as lowering blood pressure. In the relationship between omega-3 fatty acids and exercise performance, previous studies have been predicted improved endurance performance, antioxidant and anti-inflammatory responses, and effectivity against delayed-onset muscle soreness. However, the optimal dose, duration, and timing remain unclear. This review focuses on the effects of omega-3 fatty acid on muscle damage and function as evaluated by human and animal studies and summarizes its effects on muscle and nerve damage, and muscle mass and strength.

Omega-3 polyunsaturated fatty acid supplementation for improving peripheral nerve health: protocol for a systematic review

INTRODUCTION

Damage to peripheral nerves occurs in a variety of health conditions. Preserving nerve integrity, to prevent progressive nerve damage, remains a clinical challenge. Omega-3 polyunsaturated fatty acids (PUFAs) are implicated in the development and maintenance of healthy nerves and may be beneficial for promoting peripheral nerve health. The aim of this systematic review is to assess the effects of oral omega-3 PUFA supplementation on peripheral nerve integrity, including both subjective and objective measures of peripheral nerve structure and/or function.

METHODS AND ANALYSIS

A systematic review of randomised controlled trials that have evaluated the effects of omega-3 PUFA supplementation on peripheral nerve assessments will be conducted. Comprehensive electronic database searches will be performed in Ovid MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), US National Institutes of Health Clinical Trials Registry and the WHO International Clinical Trials Registry Platform. The title, abstract and keywords of identified articles will be assessed for eligibility by two reviewers. Full-text articles will be obtained for all studies judged as eligible or potentially eligible; these studies will be independently assessed by two reviewers to determine eligibility. Disagreements will be resolved by consensus. Risk of bias assessment will be performed using the Cochrane Collaboration risk of bias tool to appraise the quality of included studies. If clinically meaningful, and there are a sufficient number of eligible studies, a meta-analysis will be conducted and a summary of findings table will be provided.

ETHICS AND DISSEMINATION

This is a systematic review that will involve the analysis of previously published data, and therefore ethics approval is not required. A manuscript reporting the results of this systematic review will be published in a peer-reviewed journal and may also be presented at relevant scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42018086297.

Effect of omega-3 supplementation on neuropathy in type 1 diabetes: A 12-month pilot trial

OBJECTIVE

To test the hypothesis that 12 months of seal oil omega-3 polyunsaturated fatty acids (ω-3 PUFA) supplementation will stop the known progression of diabetic sensorimotor polyneuropathy (DSP) in type 1 diabetes mellitus (T1DM).

METHODS

Individuals with T1DM and evidence of DSP as determined by a Toronto Clinical Neuropathy Score ≥1 were recruited to participate in a single-arm, open-label trial of seal oil ω-3 PUFA supplementation (10 mL·d^-1; 750 mg eicosapentaenoic acid, 560 mg docosapentaenoic acid, and 1,020 mg docosahexaenoic acid) for 1 year. The primary outcome was the 1-year change in corneal nerve fiber length (CNFL) measured by in vivo corneal confocal microscopy, with sensory and nerve conduction measures as secondary outcomes.

RESULTS

Forty participants (53% female), aged 48 ± 14 years, body mass index 28.1 ± 5.8 with diabetes duration of 27 ± 18 years, were enrolled. At baseline, 23 participants had clinical DSP and 17 did not. Baseline CNFL was 8.3 ± 2.9 mm/mm² and increased 29% to 10.1 ± 3.7 mm/mm² (p = 0.002) after 12 months of supplementation. There was no change in nerve conduction or sensory function.

CONCLUSIONS

Twelve months of ω-3 supplementation was associated with increase in CNFL in T1DM.

CLINICALTRIALSGOVIDENTIFIER

NCT02034266.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with T1DM and evidence of DSP, 12 months of seal oil omega-3 supplementation increases CNFL.

Lipids: A Suitable Therapeutic Target in Diabetic Neuropathy?

Diabetic polyneuropathy (DPN) encompasses multiple syndromes with a common pathogenesis. Glycemic control shows a limited correlation with DPN, arguing in favor of major involvement of other factors, one of which is alterations of lipid and lipoprotein metabolism. Consistent associations have been found between plasma triglycerides/remnant lipoproteins and the risk of DPN. Studies in cultured nerve tissue or in murine models of diabetes have unveiled mechanisms linking lipid metabolism to DPN. Deficient insulin action increases fatty acids flux to nerve cells, inducing mitochondrial dysfunction, anomalous protein kinase C signaling, and perturbations in the physicochemical properties of the plasma membrane. Oxidized low-density lipoproteins bind to cellular receptors and promote generation of reactive oxygen species, worsening mitochondrial function and altering the electrical properties of neurons. Supplementation with specific fatty acids has led to prevention or reversal of different modalities of DPN in animal models. Post hoc and secondary analyses of clinical trials have found benefits of cholesterol reducing (statins and ezetimibe), triglyceride-reducing (fibrates), or lipid antioxidant (thioctic acid) therapies over the progression and severity of DPN. However, these findings are mostly hypothesis-generating. Randomized trials are warranted in which the impact of intensive plasma lipids normalization on DPN outcomes is specifically evaluated.

Omega-3 Polyunsaturated Fatty Acids Intake to Regulate Helicobacter pylori-Associated Gastric Diseases as Nonantimicrobial Dietary Approach

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), commonly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been acknowledged as essential long-chain fatty acids imposing either optimal health promotion or the rescuing from chronic inflammatory diseases such as atherosclerosis, fatty liver, and various inflammatory gastrointestinal diseases. Recent studies dealing with EPA and DHA have sparked highest interests because detailed molecular mechanisms had been documented with the identification of its receptor, G protein coupled receptor, and GPR120. In this review article, we have described clear evidences showing that n-3 PUFAs could reduce various Helicobacter pylori- (H. pylori-) associated gastric diseases and extended to play even cancer preventive outcomes including H. pylori-associated gastric cancer by influencing multiple targets, including proliferation, survival, angiogenesis, inflammation, and metastasis. Since our previous studies strongly concluded that nonantimicrobial dietary approach for reducing inflammation, for instance, application of phytoceuticals, probiotics, natural products including Korean red ginseng, and walnut plentiful of n-3 PUFAs, might be prerequisite step for preventing H. pylori-associated gastric cancer as well as facilitating the rejuvenation of precancerous atrophic gastritis, these beneficial lipids can restore or modify inflammation-associated lipid distortion and correction of altered lipid rafts to send right signaling to maintain healthy stomach even after chronic H. pylori infection.

Rat Models of Diet-Induced Obesity and High Fat/Low Dose Streptozotocin Type 2 Diabetes: Effect of Reversal of High Fat Diet Compared to Treatment with Enalapril or Menhaden Oil on Glucose Utilization and Neuropathic Endpoints

We examined whether reversal of high fat diet, stimulating weight loss, compared to two treatments previously shown to have beneficial effects, could improve glucose utilization and peripheral neuropathy in animal models of obesity and type 2 diabetes. Rats were fed a high fat diet and treated with a low dose of streptozotocin to create models of diet induced obesity or type 2 diabetes, respectively. Afterwards, rats were transferred to a normal diet or treated with enalapril or dietary enrichment with menhaden oil for 12 weeks. Obesity and to a greater extent type 2 diabetes were associated with impaired glucose utilization and peripheral neuropathy. Placing obese rats on a normal diet improved glucose utilization. Steatosis but not peripheral neuropathy was improved after placing obese or diabetic rats on a normal diet. Treating obese and diabetic rats with enalapril or a menhaden oil enriched diet generally improved peripheral neuropathy endpoints. In summary, dietary improvement with weight loss in obese or type 2 diabetic rats was not sufficient to correct peripheral neuropathy. These results further stress the need for discovery of a comprehensive treatment for peripheral neuropathy.

Enriching the diet with menhaden oil improves peripheral neuropathy in streptozotocin-induced type 1 diabetic rats

The purpose of this study was to determine the effect of supplementing the diet of type 1 diabetic rats with menhaden oil on diabetic neuropathy. Menhaden oil is a natural source for n-3 fatty acids, which have been shown to have beneficial effects in cardiovascular disease and other morbidities. Streptozotocin-induced diabetic rats were used to examine the influence of supplementing their diet with 25% menhaden oil on diabetic neuropathy. Both prevention and intervention protocols were used. Endpoints included motor and sensory nerve conduction velocity, thermal and mechanical sensitivity, and innervation and sensitivity of the cornea and hindpaw. Diabetic neuropathy as evaluated by the stated endpoints was found to be progressive. Menhaden oil did not improve elevated HbA1C levels or serum lipid levels. Diabetic rats at 16-wk duration were thermal hypoalgesic and had reduced motor and sensory nerve conduction velocities, and innervation and sensitivity of the cornea and skin were impaired. These endpoints were significantly improved with menhaden oil treatment following the prevention or intervention protocol. We found that supplementing the diet of type 1 diabetic rats with menhaden oil improved a variety of endpoints associated with diabetic neuropathy. These results suggest that enriching the diet with n-3 fatty acids may be a good treatment strategy for diabetic neuropathy.

The role of long chain fatty acids and their epoxide metabolites in nociceptive signaling

Lipid derived mediators contribute to inflammation and the sensing of pain. The contributions of omega-6 derived prostanoids in enhancing inflammation and pain sensation are well known. Less well explored are the opposing anti-inflammatory and analgesic effects of the omega-6 derived epoxyeicosatrienoic acids. Far less has been described about the epoxidized metabolites derived from omega-3 long chain fatty acids. The epoxide metabolites are turned over rapidly with enzymatic hydrolysis by the soluble epoxide hydrolase being the major elimination pathway. Despite this, the overall understanding of the role of lipid mediators in the pathology of chronic pain is growing. Here, we review the role of long chain fatty acids and their metabolites in alleviating both acute and chronic pain conditions. We focus specifically on the epoxidized metabolites of omega-6 and omega-3 long chain fatty acids as well as a novel strategy to modulate their activity in vivo.

Partial replacement with menhaden oil improves peripheral neuropathy in high-fat-fed low-dose streptozotocin type 2 diabetic rat

Aims. To determine the effect of partial replacement of a high-fat diet with menhaden oil on diabetic neuropathy in an animal model of type 2 diabetes. Materials and Methods. High-fat/low-dose streptozotocin diabetic rats were used to examine the influence of replacing 50% of the source of the high-fat diet (lard) with menhaden oil, a natural source of n-3 fatty acids, on diabetic neuropathy. Endpoints included analyses of glucose tolerance, fatty liver disease, serum and liver fatty acid composition, serum lipid and adiponectin levels, motor and sensory nerve conduction velocity, thermal sensitivity and innervation of the hindpaw. Results. Diabetic rats were insulin resistant and menhaden oil did not improve whole animal glucose utilization. Menhaden oil did not improve elevated HbA₁C levels or serum lipid levels but serum levels of adiponectin were significantly increased and hepatic steatosis was significantly improved. Diabetic rats were thermal hypoalgesic, had reduced motor and sensory nerve conduction velocities and intraepidermal nerve fiber profiles were decreased in the hindpaw and these endpoints were significantly improved with menhaden oil. Conclusions. We found that enrichment of a high-fat diet with menhaden oil improved a number of endpoints associated with diabetic neuropathy.

Omega-3 fatty acids are protective against paclitaxel-induced peripheral neuropathy: a randomized double-blind placebo controlled trial

Background

Axonal sensory peripheral neuropathy is the major dose-limiting side effect of paclitaxel.Omega-3 fatty acids have beneficial effects on neurological disorders from their effects on neurons cells and inhibition of the formation of proinflammatory cytokines involved in peripheral neuropathy.

Methods

This study was a randomized double blind placebo controlled trial to investigate the efficacy of omega-3 fatty acids in reducing incidence and severity of paclitaxel-induced peripheral neuropathy (PIPN). Eligible patients with breast cancer randomly assigned to take omega-3 fatty acid pearls, 640 mg t.i.d during chemotherapy with paclitaxel and one month after the end of the treatment or placebo. Clinical and electrophysiological studies were performed before the onset of chemotherapy and one month after cessation of therapy to evaluate PIPN based on "reduced Total Neuropathy Score".

Results

Twenty one patients (70%) of the group taking omega-3 fatty acid supplement (n = 30) did not develop PN while it was 40.7%( 11 patients) in the placebo group(n = 27). A significant difference was seen in PN incidence (OR = 0.3, .95% CI = (0.10-0.88), p = 0.029). There was a non-significant trend for differences of PIPN severity between the two study groups but the frequencies of PN in all scoring categories were higher in the placebo group (0.95% CI = (−2.06 -0.02), p = 0.054).

Conclusions

Omega-3 fatty acids may be an efficient neuroprotective agent for prophylaxis against PIPN. Patients with breast cancer have a longer disease free survival rate with the aid of therapeutical agents. Finding a way to solve the disabling effects of PIPN would significantly improve the patients’ quality of life.

Trial registration

This trial was registered at ClinicalTrials.gov (NCT01049295)

Fish-oil supplementation enhances the effects of strength training in elderly women

BACKGROUND

Muscle force and functional capacity generally decrease with aging in the older population, although this effect can be reversed, attenuated, or both through strength training. Fish oil (FO), which is rich in n-3 (omega-3) PUFAs, has been shown to play a role in the plasma membrane and cell function of muscles, which may enhance the benefits of training. The effect of strength training and FO supplementation on the neuromuscular system of the elderly has not been investigated.

OBJECTIVE

The objective was to investigate the chronic effect of FO supplementation and strength training on the neuromuscular system (muscle strength and functional capacity) of older women.

DESIGN

Forty-five women (aged 64 ± 1.4 y) were randomly assigned to 3 groups. One group performed strength training only (ST group) for 90 d, whereas the others performed the same strength-training program and received FO supplementation (2 g/d) for 90 d (ST90 group) or for 150 d (ST150 group; supplemented 60 d before training). Muscle strength and functional capacity were assessed before and after the training period.

RESULTS

No differences in the pretraining period were found between groups for any of the variables. The peak torque and rate of torque development for all muscles (knee flexor and extensor, plantar and dorsiflexor) increased from pre- to posttraining in all groups. However, the effect was greater in the ST90 and ST150 groups than in the ST group. The activation level and electromechanical delay of the muscles changed from pre- to posttraining only for the ST90 and ST150 groups. Chair-rising performance in the FO groups was higher than in the ST group.

CONCLUSIONS

Strength training increased muscle strength in elderly women. The inclusion of FO supplementation caused greater improvements in muscle strength and functional capacity.

Date fruit extract is a neuroprotective agent in diabetic peripheral neuropathy in streptozotocin-induced diabetic rats: a multimodal analysis

Background. To study the effects of an aqueous extract of date fruit (Phoenix dactylifera L. Arecaceae) diet on diabetic polyneuropathy (DPN) in streptozotocin- (STZ-) induced diabetic rats. Methods. The effects of a date fruit extract (DFE) diet on diabetic neuropathy in STZ-induced diabetic rats were evaluated and compared with a nondiabetic control group, diabetic control group (sham), and vehicle group with respect to the following parameters: open field behavioral test, motor nerve conduction velocity (MNCV), and morphological observations. Results. In the model of STZ-induced of diabetic neuropathy, chronic treatment for 6 weeks with DFE counteracted the impairment of the explorative activity of the rats in an open field behavioral test and of the conduction velocity of the sciatic nerve (MNCV). In addition, pretreatment with DFE significantly reversed each nerve diameter reduction in diabetic rats. Conclusion. DFE treatment shows efficacy for preventing diabetic deterioration and for improving pathological parameters of diabetic neuropathy in rats, as compared with control groups.

Gender specific influence of fish oil or atorvastatin on functional properties of renal Na,K-ATPase in healthy Wistar and hypertriglyceridemic rats

For better understanding of pathophysiological processes leading to increased retention of sodium as a consequence of hyperlipidemia, the properties of renal Na,K-ATPase, a key enzyme involved in maintaining sodium homeostasis in the organism, were studied. Enzyme kinetics of renal Na,K-ATPase were used for characterization of ATP- and Na(+)-binding sites after administration of fish oil (FO) (30 mg·day(-1)) or atorvastatin (0.5 mg·100 g(-1)·day(-1)) to healthy Wistar rats and rats with hereditary hypertriglyceridemia of both genders. Untreated healthy Wistar and also hypertriglyceridemic female rats revealed higher Na,K-ATPase activity as compared to respective untreated male groups. Hypertriglyceridemia itself was accompanied with higher Na,K-ATPase activity in both genders. Fish oil improved the enzyme affinity to ATP and Na(+), as indicated by lowered values of K(m) and K(Na) in Wistar female rats. In Wistar male rats FO deteriorated the enzyme in the vicinity of the Na(+)-binding site as revealed from the increased K(Na) value. In hypertriglyceridemic rats FO induced a significant effect only in females in the vicinity of the sodium binding sites resulting in improved affinity as documented by the lower value of K(Na). Atorvastatin aggravated the properties of Na,K-ATPase in both genders of Wistar rats. In hypertriglyceridemic rats protection of Na,K-ATPase was observed, but this effect was bound to females only. Both treatments protected renal Na,K-ATPase in a gender specific mode, resulting probably in improved extrusion of excessive intracellular sodium out of the cell affecting thus the retention of sodium in hHTG females only.

The comparative protective effects of ganoderma spores lipid and fish oil on N-methyl-N-nitrosourea-induced photoreceptor cell lesion in rats

Purpose. To compare Ganoderma spores lipid (GSL) and fish oil (FO) in inhibiting retinal photoreceptor cell lesions induced by N-methyl-N-nitrosourea (MNU) in rats. Methods. 120 rats were untreated (normal control, NC group) or treated with a single intraperitoneal injection of 40 mg/kg MNU (MNU group) then treated with GSL (GSL group) or FO (FO group). Eyes were obtained at 1, 3, 5, 7, and 10 days. Results. Light microscopy assay demonstrated that GSL and FO alleviated rat retinal photoreceptor cell damage (GSL and FO versus MNU group P < .001) similarly (GSL versus FO group P = .980). Electron microscopy confirmed that GSL and FO reversed damage to photoreceptor segments and photoreceptor cell nuclei. GSL-treated rats showed significantly elevated a-wave and b-wave amplitudes over MNU group (P < .05) but less than NC group (P < .05) and not significantly different from FO group (P > .05). Conclusion. GSL, like FO, alleviates rat retinal photoreceptor cell damage induced by MNU.

Effects of maternal malnutrition and postnatal nutritional rehabilitation on brain fatty acids, learning, and memory

Undernutrition still affects mothers and children in developing countries and thus remains the major focus of nutritional intervention efforts. Neuronal development, which classically includes neurogenesis, migration, maturation, and synapse refinement, begins in utero and continues into the early postnatal period. These processes are not only genetically regulated but also clearly susceptible to environmental manipulation. Dietary deprivation during early life is known to have adverse effects on brain anatomy, physiology, and biochemistry, and may even lead to permanent brain damage. Although all nutrients are important for the structural development of the central nervous system, lipids such as long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (22:6 n-3) and arachidonic acid (20:4 n-6), are important for normal brain development. The purpose of this literature review is to examine how early undernutrition involving a deficiency in long-chain polyunsaturated fatty acids can affect brain development and function and produce deficits in spatial cognitive learning ability.

Sciatic nerve of diabetic rat treated with epoetin delta: effects on C-fibers and blood vessels including pericytes

In diabetes mellitus (DM) reduced motor and sensory properties of peripheral nerves are linked with the dysfunction of neural vasculature. We investigated C-fibers and microvessels of sciatic nerve of normal, DM, and DM + epoetin delta-treated rats. C-fibers immunoreactive for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH), epoetin receptor (EpoR), and common beta receptor subunit of the interleukin 3 receptor (IL-3Rbeta) were present in all rats, whereas in DM and epoetin-treated rats C-fibers also showed neuronal (nNOS) and inducible (iNOS) nitric oxide synthases. The cross-sectional area of CGRP-positive C-fibers was decreased in DM, but it recovered after epoetin treatment. In all conditions, vascular endothelium showed scarce immunolabeling for endothelial nitric oxide synthase (eNOS); the profound immunoreactivity for eNOS, EpoR, and IL-3Rbeta was in pericytes. Some perivascular autonomic nerves were damaged and IL-3Rbeta positive. Findings are discussed in terms of declined sensory conduction velocity in DM, its improvement after epoetin treatment, and the possible vascular contribution to these phenomena.

Therapeutic potential of n-3 polyunsaturated fatty acids in disease

PURPOSE

The potential therapeutic benefits of supplementation with n-3 polyunsaturated fatty acids (PUFAs) in various diseases are reviewed, and the antiinflammatory actions, activity, and potential drug interactions and adverse effects of n-3 PUFAs are discussed.

SUMMARY

Fish oils are an excellent source of long-chain n-3 PUFAs, such as eicosapentaenoic acid and docosahexaenoic acid. After consumption, n-3 PUFAs can be incorporated into cell membranes and reduce the amount of arachidonic acid available for the synthesis of proinflammatory eicosanoids (e.g., prostaglandins, leukotrienes). Likewise, n-3 PUFAs can also reduce the production of inflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1, and interleukin-6. Considerable research has been conducted to evaluate the potential therapeutic effects of fish oils in numerous conditions, including arthritis, coronary artery disease, inflammatory bowel disease, asthma, and sepsis, all of which have inflammation as a key component of their pathology. Additional investigations into the use of supplementation with fish oils in patients with neural injury, cancer, ocular diseases, and critical illness have recently been conducted. The most commonly reported adverse effects of fish oil supplements are a fishy aftertaste and gastrointestinal upset. When recommending an n-3 PUFA, clinicians should be aware of any possible adverse effect or drug interaction that, although not necessarily clinically significant, may occur, especially for patients who may be susceptible to increased bleeding (e.g., patients taking warfarin).

CONCLUSION

The n-3 PUFAs have been shown to be efficacious in treating and preventing various diseases. The wide variation in dosages and formulations used in studies makes it difficult to recommend dosages for specific treatment goals.

The Residual Risk Reduction Initiative: a call to action to reduce residual vascular risk in dyslipidaemic patient

Despite current standards of care aimed at achieving targets for low-density lipoprotein (LDL) cholesterol, blood pressure and glycaemia, dyslipidaemic patients remain at high residual risk of vascular events. Atherogenic dyslipidaemia, specifically elevated triglycerides and low levels of high-density lipoprotein (HDL) cholesterol, often with elevated apolipoprotein B and non-HDL cholesterol, is common in patients with established cardiovascular disease, type 2 diabetes, obesity or metabolic syndrome and is associated with macrovascular and microvascular residual risk. The Residual Risk Reduction Initiative (R3I) was established to address this important issue. This position paper aims to highlight evidence that atherogenic dyslipidaemia contributes to residual macrovascular risk and microvascular complications despite current standards of care for dyslipidaemia and diabetes, and to recommend therapeutic intervention for reducing this, supported by evidence and expert consensus. Lifestyle modification is an important first step. Additionally, pharmacotherapy is often required. Adding niacin, a fibrate or omega-3 fatty acids to statin therapy improves achievement of all lipid risk factors. Outcomes studies are evaluating whether these strategies translate to greater clinical benefit than statin therapy alone. In conclusion, the R3I highlights the need to address with lifestyle and/or pharmacotherapy the high level of residual vascular risk among dyslipidaemic patients who are treated in accordance with current standards of care.

At low doses, a gamma-linolenic acid-lipoic acid conjugate is more effective than docosahexaenoic acid-enriched phospholipids in preventing neuropathy in diabetic rats

A deficiency in essential fatty acid metabolism has been reported in diabetes. Nutritional supplementations with (n-6) or (n-3) PUFA have differential efficiency on parameters of diabetic neuropathy, including nerve conduction velocity (NCV) and nerve blood flow (NBF). The aim of this study was to compare the neuroprotective effects of gamma-linolenic acid (GLA)-lipoic acid (LA) conjugate (GLA-LA) and docosahexaenoic acid (DHA)-enriched phospholipids (PL) supplementations on NCV and NBF. Streptozotocin-induced diabetic (D) and control (C) rats were supplemented for 8 wk with either DHA-enriched PL at a dose of 30 mg.kg-1.d-1 (DDHA and CDHA) or with corn oil enriched with GLA-LA at a dose of 30 mg.kg-1.d-1 (DGLA and CGLA). Moreover, a C and D group received no supplementation. After 8 wk, NCV (-30%) and NBF (-50%) were lower in the D group than in the C group. Supplementation with GLA-LA totally prevented the decrease in NCV and NBF in the DGLA group, in which values did not differ from group C. Supplementation with DHA only partially prevented the decrease in NCV in the DDHA group, in which value was different from groups C and D and did not affect NBF. We conclude that at the low doses used, supplementation with GLA-LA is more effective than supplementation with DHA in preventing experimental diabetic neuropathy. The difference could be due in part to an antioxidant protective effect of LA on GLA.

Modulation of phosphoinositide-protein kinase C signal transduction by omega-3 fatty acids: implications for the pathophysiology and treatment of recurrent neuropsychiatric illness

The phosphoinositide (PI)-protein kinase C (PKC) signal transduction pathway is initiated by pre- and postsynaptic Galphaq-coupled receptors, and regulates several clinically relevant neurochemical events, including neurotransmitter release efficacy, monoamine receptor function and trafficking, monoamine transporter function and trafficking, axonal myelination, and gene expression. Mounting evidence for PI-PKC signaling hyperactivity in the peripheral (platelets) and central (premortem and postmortem brain) tissues of patients with schizophrenia, bipolar disorder, and major depressive disorder, coupled with evidence that PI-PKC signal transduction is down-regulated in rat brain following chronic, but not acute, treatment with antipsychotic, mood-stabilizer, and antidepressant medications, suggest that PI-PKC hyperactivity is central to an underlying pathophysiology. Evidence that membrane omega-3 fatty acids act as endogenous antagonists of the PI-PKC signal transduction pathway, coupled with evidence that omega-3 fatty acid deficiency is observed in peripheral and central tissues of patients with schizophrenia, bipolar disorder, and major depressive disorder, support the hypothesis that omega-3 fatty acid deficiency may contribute to elevated PI-PKC activity in these illnesses. The data reviewed in this paper outline a potential molecular mechanism by which omega-3 fatty acids could contribute to the pathophysiology and treatment of recurrent neuropsychiatric illness.

Neuroprotective effect of docosahexaenoic acid-enriched phospholipids in experimental diabetic neuropathy

A deficiency in essential fatty acid metabolism has been widely reported in both human and animal diabetes. Fish oil supplementations (n-3 fatty acids), containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), were less effective on diabetic neuropathy than (n-6) fatty acids. This partial effect of (n-3) fatty acids might be attributed to the presence of EPA, a competitor of arachidonic acid, which enhanced the diabetes-induced decrease of this fatty acid in serum and tissues. For determining whether a supplementation with DHA alone could prevent neuropathy in streptozotocin-induced diabetes, diabetic rats were given daily, by gavage, liposomes containing DHA phospholipids, at a dose of 60 mg/kg. Eight weeks of diabetes induced significant decreases in nerve conduction velocity (NCV), nerve blood flow (NBF), and sciatic nerve and erythrocyte (red blood cells [RBCs]) Na,K-ATPase activities. DHA phospholipids totally prevented the decrease in NCV and NBF observed during diabetes when compared with the nonsupplemented diabetic group. DHA phospholipids also prevented the Na,K-ATPase activity decrease in RBC but not in sciatic nerve. Moreover, DHA level in sciatic nerve membranes was correlated with NCV. These results demonstrate a protective effect of daily doses of DHA on experimental diabetic neuropathy. Thus, treatment with DHA phospholipids could be suitable for evaluation in clinical trials.

Effects of cod liver oil on tissue antioxidant pathways in normal and streptozotocin-diabetic rats

Lipid disorders and increased oxidative stress may exacerbate some complications of diabetes mellitus. Previous studies have implicated the beneficial effects of some antioxidants, omega-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the protection of cells from the destructive effect of increased lipids and lipid peroxidation products. This study, therefore, was designed to investigate the effects of cod liver oil (CLO, Lysi Ltd. Island), which comprises mainly vitamin A, PUFAs, EPA and DHA. Effects were monitored on plasma lipids, lipid peroxidation products (MDA) and the activities of antioxidant enzymes, glutathione peroxidase (GSHPx) and catalase in heart, liver, kidney and lung of non-diabetic control and streptozotocin (STZ)-induced-diabetic rats. Two days after STZ-injection (55 mg kg(-1) i.p.), non-diabetic control and diabetic rats were divided randomly into two groups as untreated or treated with CLO (0.5 ml kg(-1) rat per day) for 12 weeks. Plasma glucose, triacylglycerol and cholesterol concentrations were significantly elevated in 12-week untreated-diabetic animals; CLO treatment almost completely prevented these abnormalities in triacylglycerol and cholesterol, but hyperglycaemia was partially controlled. CLO also provided better weight gain in diabetic animals. In untreated diabetic rats, MDA markedly increased in aorta, heart and liver but was not significantly changed in kidney and lung. This was accompanied by a significant increase in both GSHPx and catalase enzyme activities in aorta, heart, and liver of diabetic rats. In kidney and lung, diabetes resulted in reduced catalase while GSHPx was significantly activated. In aorta, heart, and liver, diabetes-induced changes in MDA were entirely prevented by CLO treatment. In the tissues of CLO-treated diabetic animals, GSHPx activity paralleled those of control animals. CLO treatment also caused significant improvements in catalase activities in every tissue of diabetic rats, but failed to affect MDA and antioxidant activity in control animals. The current study suggests that the treatment of diabetic rats with CLO provides better control of glucose and lipid metabolism, allows recovery of normal growth rate, prevents oxidative/peroxidative stress and ameliorates endogenous antioxidant enzyme activities in various tissues. Because CLO contains a plethora of beneficial compounds together, its use for the management of diabetes-induced complications may provide important advantages.

Favorable impact of a vegan diet with exercise on hemorheology: implications for control of diabetic neuropathy

A little-noticed clinical report indicates that a low-fat, whole-food vegan diet, coupled with daily walking exercise, leads to rapid remission of neuropathic pain in the majority of type 2 diabetics expressing this complication. Concurrent marked improvements in glycemic control presumably contribute to this benefit, but are unlikely to be solely responsible. Consideration should be given to the possibility that improved blood rheology - decreased blood viscosity and increased blood filterability - plays a prominent role in mediating this effect. There is considerable evidence that neural hypoxia, secondary to impaired endoneurial microcirculatory perfusion, is a crucial etiologic factor in diabetic neuropathy; the unfavorable impact of diabetes on hemorheology would be expected to exacerbate endoneurial ischemia. Conversely, measures which improve blood fluidity would likely have a beneficial impact on diabetic neuropathy. There is indeed evidence that vegan diets, as well as exercise training, tend to decrease the viscosity of both whole blood and plasma; reductions in hematocrit and in fibrinogen may contribute to this effect. The fact that vegan diets decrease the white cell count is suggestive of an improvement in blood filterability as well; filterability improves with exercise training owing to an increase in erythrocyte deformability. Whether these measures influence the activation of leukocytes in diabetics - an important determinant of blood filterability - remains to be determined. There are various reasons for suspecting that a vegan diet can reduce risk for other major complications of diabetes - retinopathy, nephropathy, and macrovascular disease - independent of its tendency to improve glycemic control in type 2 patients. The vegan diet/exercise strategy represents a safe, 'low-tech' approach to managing diabetes that deserves far greater attention from medical researchers and practitioners.

Dietary supplements

The amount of published information on dietary supplements mushroomed in the 1990s. In fewer than 5 years, publications increased at least 100-fold in the medical literature alone. Dietary supplements are an uncharted territory that warrants complete and accurate exploration. One should not be surprised that disease and illness may respond to dietary supplements. Nutrition is the foundation to good health, and dietary supplements may prove to be some of the most powerful medicines ever discovered. An especially exciting discovery is that dietary supplements may enhance the effects of specific drugs. This discovery may lead to more effective and safer protocols for the treatment of cancer, heart and lung disease, and a host of chronic medical conditions. Information about dietary supplements is becoming more common in the popular medical literature and is creating increased curiosity and an increased awareness. The explosion of the dietary supplement market is compelling physicians to become aware of dietary supplements. Whether or not they are used in clinical practice is a decision for the individual physician. Given the increasing number of patients who are using dietary supplements, however, it is imperative that physicians have a good understanding of this topic. Considering the increasing complexity and magnitude of this topic, physician specialization may be essential. There are many good reference books, review articles, and internet sites on specific supplements that probably should be part of every physician's reference library. The accompanying box provides a brief list of such sources.

Localization of Na,K-ATPase alpha/beta isoforms in rat sciatic nerves: effect of diabetes and fish oil treatment

The localization of the Na,K-ATPase isoenzymes in sciatic nerve remains controversial, as well as diabetes-induced changes in Na,K-ATPase isoforms. Some of these changes could be prevented by fish oil therapy. The aim of this study was to determine by confocal microscopy the distribution of Na,K-ATPase isoforms (alpha1, alpha2, alpha3, beta1, and beta2) in the sciatic nerve, the changes induced by diabetes, and the preventive effect of fish oil in diabetic neuropathy. This study was performed in three groups of rats. In the first two groups, diabetes was induced by streptozotocin and rats were supplemented daily with fish oil or olive oil at a dosage of 0.5 g/kg of body weight. The third one was a control group that was supplemented with olive oil. Five antibodies against specific epitopes of Na,K-ATPase isoenzymes were applied to stained dissociated nerve fibers with fluorescent secondary antibodies. The five isoenzymes were documented in nonspecific regions, Schwann cells (myelin), and the node of Ranvier. The localization of the alpha1, alpha2, and beta1 isoenzymes was not affected by diabetes. In contrast, diabetes induced a decrease of the alpha2 subunit (p < 0.05) and an up-regulation of the beta2 subunit (p < 0.05). These modifications were noted in both regions for alpha2 and were localized at the myelin domain only for the beta2. Fish oil supplementation prevented the diabetes-induced changes in the alpha2 subunit with an additional up-regulation. The beta2 subunit was not modified. A phenotypic change similar to nerve injury was induced by diabetes. Fish oil supplementation partially prevented some of these changes.

Depression and bipolar disorder: relationships to impaired fatty acid and phospholipid metabolism and to diabetes, cardiovascular disease, immunological abnormalities, cancer, ageing and osteoporosis. Possible candidate genes

Depression and bipolar disorder are two of the commonest illnesses in the developed world. While some patients can be treated effectively with available drugs, many do not respond, especially in the depression related to bipolar disorder. Depression is associated with diabetes, cardiovascular disease, immunological abnormalities, multiple sclerosis, cancer, osteoporosis and ageing: in each case depressed individuals have a worse outcome than non-depressed individuals. In all of these conditions there is now evidence of impaired phospholipid metabolism and impaired fatty acid-related signal transduction processes. Impaired fatty acid and phospholipid metabolism may be a primary cause of depression in many patients and may explain the interactions with other diseases. Several novel gene candidates for involvement in depression and bipolar disorder are proposed.