The Effect of Dietary Polyunsaturated Fatty Acids and Alcohol on Neurotransmitter Levels in Rat Brain

PUFA and their derivatives in neurotransmission and synapses: a new hallmark of synaptopathies

PUFA of the n-3 and n-6 families are present in high concentration in the brain where they are major components of cell membranes. The main forms found in the brain are DHA (22 :6, n-3) and arachidonic acid (20:4, n-6). In the past century, several studies pinpointed that modifications of n-3 and n-6 PUFA levels in the brain through dietary supply or genetic means are linked to the alterations of synaptic function. Yet, synaptopathies emerge as a common characteristic of neurodevelopmental disorders, neuropsychiatric diseases and some neurodegenerative diseases. Understanding the mechanisms of action underlying the activity of PUFA at the level of synapses is thus of high interest. In this frame, dietary supplementation in PUFA aiming at restoring or promoting the optimal function of synapses appears as a promising strategy to treat synaptopathies. This paper reviews the link between dietary PUFA, synapse formation and the role of PUFA and their metabolites in synaptic functions.

Polyunsaturated fatty acids moderate the effect of poor sleep on depression risk

Although potentially modifiable risk factors for interferon-alpha (IFN-α)-associated depression (IFN-MDD) have been identified, it is not currently known how they interact to confer risk. In the present study we prospectively investigated interactions among poor sleep quality, high-stress, pre-existing depressive symptoms, and polyunsaturated fatty acid status. Non-depressed hepatitis C patients (n=104) were followed prospectively during IFN-α therapy. IFN-MDD occurs in 20-40% of patients and was diagnosed using the Structured Clinical Interview of DSM-IV (SCID-IV), with incidence examined using Cox regression. Baseline Pittsburgh Sleep Quality Inventory (PSQI), Perceived Stress Scale (PSS), Beck Depression Inventory (BDI), and a range of plasma long-chain fatty acid levels were measured (gas chromatography) - focusing on the ratio of arachidonic acid (AA) to docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (AA/EPA+DHA). The AA/EPA+DHA ratio (Β=0.40 ± 0.16; p=0.006), PSQI (Β=0.12 ± 0.04; p=0.001), PSS (Β=0.07 ± 0.02; p<0.001), and baseline BDI (Β=0.05 ± 0.02; p<0.001) each individually predicted IFN-MDD incidence. In step-wise Cox regression eliminating non-significant variables, two interactions remained significantly predictive: PSQI*AA/EPA+DHA (p=0.008) and PSS*AA/EPA+DHA (p=0.01). Receiver Operator Curves (ROC) were used to examine the specificity and sensitivity of IFN-MDD prediction. When sleep was normal (PSQI<5), AA/EPA+DHA was strongly predictive of IFN-MDD (AUC=91 ± 6; p=0.002). For example, among those with AA/EPA+DHA less than the median (4.15), none with PSQI<5 developed depression. Conversely, neither PSS nor PSQI was statistically associated with depression risk in those with an elevated AA/EPA+DHA ratio. These data demonstrate that the AA/EPA+DHA ratio moderates the effect of poor sleep on risk for developing IFN-MDD and may have broader implications for predicting and preventing MDD associated with inflammation.

Serum n-3 polyunsaturated fatty acids and psychological distress in early pregnancy: Adjunct Study of Japan Environment and Children's Study

N-3 polyunsaturated fatty acids (PUFAs), especially long-chain types such as docosahexaenoic acid, are important nutrients in pregnancy, but the relationship between n-3 PUFA levels and perinatal and postnatal depression remains controversial. This study examined the possible relationship between serum n-3 PUFA levels and psychological distress among expectant mothers in early pregnancy. Data and specimen samples were obtained in a birth cohort study started at Toyama Regional Center in July 2012 as an adjunct study of the Japan Environment and Children's Study. Blood samples were collected at 9-14 weeks' gestation (75% of samples) or after 15 weeks (25%). Subjects with a Kessler Psychological Distress Scale score (K6) ⩾ 9 were assigned to the psychological distress group (n=283). The control group (n=283) was matched for age, educational level and family income. Fatty acid composition was determined from serum samples by gas chromatography. Associations between fatty acid levels and incident psychological distress were evaluated by logistic regression. After adjusting for possible confounders, eicosapentaenoic acid showed an inverse association with risk of psychological distress, with an odds ratio of 0.47 (95% confidence interval: 0.30, 0.73) for the highest tertile. This inverse association remained even after applying a higher cutoff score (K6 ⩾ 13) indicating severe psychological distress (74 pairs). We believe this is the first study to reveal the associations between serum n-3 PUFAs and risk of psychological distress in early pregnancy. Further research is required to verify the causality of these associations.

Anger induced by interferon-alpha is moderated by ratio of arachidonic acid to omega-3 fatty acids

OBJECTIVE

Anger worsens in some patients during interferon-alpha (IFN-α) therapy. Elevated anger has also been associated with lower long-chain omega-3 (LCn-3) fatty acid levels. We examined whether fatty acids could influence vulnerability to anger during IFN-α exposure.

METHODS

Plasma arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) levels were determined prior to IFN-α therapy by mass spectroscopy. Repeated-measure analyses examined the relationship between AA/EPA+DHA and the subsequent development of labile anger and irritability in 82 subjects who prospectively completed the Anger, Irritability, and Assault Questionnaire (AIAQ) during the first eight weeks of IFN-α therapy.

RESULTS

Prior to IFN-α therapy, AA/EPA+DHA did not correlate with either labile anger or irritability. Pre-treatment AA/EPA+DHA did correlate with the subsequent maximal increase in labile anger during IFN-α therapy (r=0.33; p=0.005). Over time, labile anger increased more in subjects with above median AA/EPA+DHA ratios (p<0.05). Of the 17 subjects ultimately requiring psychiatric intervention for anger, 14/17 had above-median AA/EPA+DHA ratios (p=0.009). There was also an interaction with the tumor necrosis factor-alpha (TNF-α) promoter polymorphism (A-308G), such that only those with both elevated AA/EPA+DHA and the A allele had increased labile anger (p=0.001). In an additional 18 subjects, we conversely observed that selective serotonin reuptake inhibitor treatment was associated with increased irritability during IFN-α therapy.

CONCLUSION

LCn-3 fatty acid status may influence anger development during exposure to elevated inflammatory cytokines, and may interact with genetic risk for increased brain TNF-α. LCn-3 supplements may be one strategy for minimizing this adverse side effect of IFN-α.

Fatty acid composition in the postmortem amygdala of patients with schizophrenia, bipolar disorder, and major depressive disorder

Previous studies with postmortem brain tissues showed abnormalities in n-3 polyunsaturated fatty acids (PUFAs) in the orbitofrontal cortex of individuals with schizophrenia and mood disorders. However, in the hippocampus, we were not able to find any significant differences in PUFAs except for small differences in n-6 PUFAs. In the present study we investigated levels of PUFAs in the amygdala of postmortem brains from patients with schizophrenia, bipolar disorder, and major depressive disorder (MDD) compared with those of unaffected controls. Amygdala samples from patients with schizophrenia (n = 15), bipolar disorder (n = 15), or MDD (n = 15), and controls matched for age, sex, and five other confounding factors (n = 15) were analyzed for fatty acid composition by gas chromatography. In contrast to previous studies of the orbitofrontal cortex and hippocampus, we were unable to find any significant differences in major PUFAs. The relative compositions of docosahexaenoic acid (DHA), the major n-3 PUFA, were 10.0 ± 1.1%, 10.0 ± 1.3%, 9.3 ± 1.3%, and 9.7 ± 1.1%, respectively, in patients with schizophrenia, bipolar disorder, and MDD and unaffected controls (not significantly different). The corresponding relative compositions of arachidonic acid (AA), the major n-6 PUFA, were 9.0 ± 0.8%, 9.2 ± 0.5%, 9.4 ± 0.7%, and 9.4 ± 0.7%, respectively (not significantly different). Significant differences were found in some of the other fatty acids. In particular, we found a 6.5% increase in palmitic acid and 6.2% decrease in oleic acid in patients with MDD compared to controls. With regard to schizophrenia, there was an 8.0% decrease in docosatetraenoic acid compared to controls. In conclusion, the changes in DHA and/or AA seen in orbitofrontal cortex and hippocampus were not observed in amygdala. These changes may be specific to particular brain regions.

Higher n-3 fatty acids are associated with more intense fenfluramine-induced ACTH and cortisol responses among cocaine-abusing men

Preclinical studies have shown that diets supplemented with or deficient in n-3 polyunsaturated fatty acids (PUFAs) could influence serotonergic neurotransmission, but information about their effects on the serotonergic function of humans is scant. Therefore, simultaneous assessments of n-3 PUFAs and of the adrenocorticotropic hormone (ACTH) and cortisol responses to challenges with the serotonin (5-HT) probe d,l-fenfluramine (FEN) were performed in 25 cocaine-abusing men and 12 control subjects. Cocaine abusers were tested 18 days after their admission to a closed ward. ACTH and cortisol were measured in plasma samples collected on two testing days separated by 48 h following the random administration of 60 mg of FEN or placebo. Fatty acids were measured in the first test day samples. Patients' FEN-induced ACTH rises were significantly and positively correlated with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Patients' cortisol rises were positively and significantly correlated with EPA but not with DHA. There were no significant correlations between hormonal responses and pre-hospitalization cocaine use parameters. Control subjects' responses to FEN were not correlated with any PUFA. In conclusion, higher EPA and DHA levels were associated with a more intense FEN-induced ACTH response and higher EPA levels with a more intense cortisol response in cocaine-abusing men withdrawn from cocaine but not in control subjects. These findings support and expand existing evidence that EPA and DHA could influence 5-HT function in some human subgroups.

Effects of ethyl-eicosapentaenoic acid omega-3 fatty acid supplementation on hot flashes and quality of life among middle-aged women: a double-blind, placebo-controlled, randomized clinical trial

OBJECTIVE

To compare the effects of enriched ethyl-eicosapentaenoic acid (E-EPA) omega-3 fatty acid supplementation with those of placebo on hot flashes (HFs) and quality of life among middle-aged women.

METHODS

Women were considered for participation if they were between 40 and 55 years of age and had moderate to severe psychological distress. A total of 120 women were randomly assigned to E-EPA or placebo for 8 weeks. Only women with HFs were included in this analysis (E-EPA, n = 45; placebo, n = 46). Outcomes were changes from baseline to week 8 postintervention regarding hot flash (HF) frequency (number of HFs per day), intensity and score (frequency x intensity), and Menopause-specific Quality of Life questionnaire scores.

RESULTS

At baseline, the average number of HFs was 2.8 per day. After 8 weeks, HF frequency and score decreased significantly in the E-EPA group compared with the placebo group. There was no difference in the change in HF intensity between groups. Frequency of HFs declined by a mean of 1.58 per day (95% CI, -2.18 to -0.98) in the E-EPA group and by 0.50 per day (95% CI, -1.20 to 0.20) in the placebo group. The odds of being a responder among those taking E-EPA were about three times greater than among those taking placebo (odds ratio, 2.70; 95% CI, 1.03-7.03; P = 0.04). Menopause-Specific Quality of Life scores improved significantly over time in both groups but no significant differences were noted between them.

CONCLUSIONS

Supplementation with E-EPA omega-3 fatty acid reduced HF frequency and improved the HF score relative to placebo. These results need to be confirmed by a clinical trial specifically designed to evaluate HFs in more symptomatic women.

Prevention of alcoholic fatty liver and mitochondrial dysfunction in the rat by long-chain polyunsaturated fatty acids

BACKGROUND/AIMS

We reported that reduced dietary intake of polyunsaturated fatty acids (PUFA) such as arachidonic (AA,20:4n6,omega-6) and docosahexaenoic (DHA,22:6n3,omega-3) acids led to alcohol-induced fatty liver and fibrosis. This study was aimed at studying the mechanisms by which a DHA/AA-supplemented diet prevents alcohol-induced fatty liver.

METHODS

Male Long-Evans rats were fed an ethanol or control liquid-diet with or without DHA/AA for 9 weeks. Plasma transaminase levels, liver histology, oxidative/nitrosative stress markers, and activities of oxidatively-modified mitochondrial proteins were evaluated.

RESULTS

Chronic alcohol administration increased the degree of fatty liver but fatty liver decreased significantly in rats fed the alcohol-DHA/AA-supplemented diet. Alcohol exposure increased oxidative/nitrosative stress with elevated levels of ethanol-inducible CYP2E1, nitric oxide synthase, nitrite and mitochondrial hydrogen peroxide. However, these increments were normalized in rats fed the alcohol-DHA/AA-supplemented diet. The number of oxidatively-modified mitochondrial proteins was markedly increased following alcohol exposure but significantly reduced in rats fed the alcohol-DHA/AA-supplemented diet. The suppressed activities of mitochondrial aldehyde dehydrogenase, ATP synthase, and 3-ketoacyl-CoA thiolase in ethanol-exposed rats were also recovered in animals fed the ethanol-DHA/AA-supplemented diet.

CONCLUSIONS

Addition of DHA/AA prevents alcohol-induced fatty liver and mitochondrial dysfunction in an animal model by protecting various mitochondrial enzymes most likely through reducing oxidative/nitrosative stress.

Long-chain n-3 polyunsaturated fatty acids decrease feelings of anger in substance abusers

It has been suggested that low levels of n-3 polyunsaturated fatty acids (PUFAs) play a role in the pathophysiology of some psychiatric disorders. In light of the existence of strong associations between high-frequency and high-severity aggressive behaviors and substance use disorders and of our observation that substance abusers have poor dietary habits, the possibility that the administration of supplements of n-3 PUFAs would decrease their anger levels was explored. A lifelong history of aggressive behaviors and problems with the law was obtained in 24 patients. Thirteen patients received on a daily basis capsules containing 3 g of n-3 PUFAs (EPA+DHA). Eleven patients received placebo capsules. The trial was double-blind, randomized, and lasted 3 months. An anger scale was administered at baseline and every month thereafter. Six PUFA group patients and eight placebo group patients were followed for an additional 3 months after treatment discontinuation. Four patients in each group had a history of assaultive behavior. The baseline fish and n-3 PUFA intakes of these eight patients were significantly lower than those of the non-aggressive patients. When given for 3 months, n-3 PUFAs were superior to placebo in diminishing anger scores. Scores remained decreased for 3 months following treatment discontinuation. These data provide further support for emerging evidence indicating that supplementation with long-chain n-3 PUFAs could be beneficial in the treatment of some individuals with aggressive tendencies.

Aggressive dogs are characterized by low omega-3 polyunsaturated fatty acid status

Canine aggressive behaviour is one of the most common problems being reported by dog owners. However, the biochemical basis of this phenomenon remains unclear. In humans, alterations in omega-3 plasma polyunsatured fatty acids and elevated omega6/omega-3 ratio have been linked to behavioural alterations, including aggression. Thus far, however, the relationship between plasma polyunsatured fatty acid status and aggression has not been investigated in the dog. In the present study we sought to investigate whether polyunsatured fatty acid status could be altered in plasma of pathologically aggressive Canis familiaris. Eighteen adult male German Shepherd dogs, aged 4.9 +/- 0.9 years, showing no clinical signs but aggression, were investigated. Eighteen healthy male dogs, aged 4.8 +/- 0.7 years, with a negative history of behavioural and neurological disorders served as controls. Baseline fasting plasma polyunsatured fatty acid composition was determined by gas chromatography. Compared to normal dogs, aggressive dogs showed lower docosahexaenoic acid (22:6 n-3) concentrations and a higher omega6/omega-3 ratio. In addition, they showed reduced cholesterol and bilirubin concentrations compared to their normally behaving counterparts. Altogether, our results suggest that low omega-3 fatty acids may adversely impact behaviour in dogs, resulting in greater propensity to aggression. However, given the cross-sectional design of our study, we cannot claim any causal relationship between the presence of alterations in fatty acid status and canine aggressiveness. Whether omega-3 fatty acids supplementation may be useful to reduce aggressive behaviour in the dog deserves further investigation.

Omega-3 fatty acid deficiencies in neurodevelopment, aggression and autonomic dysregulation: opportunities for intervention

Mechanisms by which aggressive and depressive disorders may be exacerbated by nutritional deficiencies in omega-3 fatty acids are considered. Early developmental deficiencies in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) may lower serotonin levels at critical periods of neurodevelopment and may result in a cascade of suboptimal development of neurotransmitter systems limiting regulation of the limbic system by the frontal cortex. Residual developmental deficits may be manifest as dysregulation of sympathetic responses to stress including decreased heart rate variability and hypertension, which in turn have been linked to behavioral dysregulation. Little direct data are available to disentangle residual neurodevelopmental effects from reversible adult pathologies. Ensuring optimal intakes of omega-3 fatty acids during early development and adulthood shows considerable promise in preventing aggression and hostility.

Polyunsaturated fatty acid status and relapse vulnerability in cocaine addicts

There is mounting evidence that low levels of some polyunsaturated fatty acids (PUFAs) play a role in the pathophysiology of depressive and aggressive disorders, including homicides. There is also evidence derived mostly from the animal literature that PUFAs could play a role in the abuse of substances through their action on central serotonergic and dopaminergic systems that are both known to play a role in reward mechanisms. In this study, we explored the possibility that the relapse rates of cocaine addicts discharged after a period of detoxification on an inpatient unit would be associated with their PUFA status. Thirty-eight patients were enrolled in the study. PUFA status was assessed only at baseline, shortly after admission. Resumption of substance use was assessed 3 months, 6 months and 1 year following discharge. Thirty-two patients remained available for follow-up for the duration of the study. Subjects who relapsed at 3 months had significantly lower baseline levels of total n-6 PUFAs, linoleic acid (LA, 18:2n-6), arachidonic acid (AA, 20:4n-6) and total n-3 PUFAs when compared to non-relapsers by ANCOVAs with age and weight as covariates. Lower baseline total n-6 PUFAs, LA and AA continued to predict relapse 6 months and 12 months following discharge. Age, marital status, educational level, cocaine use parameters or psychopathology did not differ between relapsers and non-relapsers. In conclusion, low PUFA status at baseline was a better predictor of relapse than cocaine use, sociodemographic or clinical parameters. These data suggest, but do not prove, the existence of a causal relationship between n-6 or n-3 status and relapse vulnerability in cocaine addicts, and provide a rationale for the exploration of possible relationships between relapse to addictive disorders and PUFA status in observational and interventional trials.