Effect of fish oil and coconut fat supplementation on depressive-type behavior and corticosterone levels of prenatally stressed male rats

Nutritional interventions to counteract the detrimental consequences of early-life stress

Exposure to stress during sensitive developmental periods comes with long term consequences for neurobehavioral outcomes and increases vulnerability to psychopathology later in life. While we have advanced our understanding of the mechanisms underlying the programming effects of early-life stress (ES), these are not yet fully understood and often hard to target, making the development of effective interventions challenging. In recent years, we and others have suggested that nutrition might be instrumental in modulating and possibly combatting the ES-induced increased risk to psychopathologies and neurobehavioral impairments. Nutritional strategies are very promising as they might be relatively safe, cheap and easy to implement. Here, we set out to comprehensively review the existing literature on nutritional interventions aimed at counteracting the effects of ES on neurobehavioral outcomes in preclinical and clinical settings. We identified eighty six rodent and ten human studies investigating a nutritional intervention to ameliorate ES-induced impairments. The human evidence to date, is too few and heterogeneous in terms of interventions, thus not allowing hard conclusions, however the preclinical studies, despite their heterogeneity in terms of designs, interventions used, and outcomes measured, showed nutritional interventions to be promising in combatting ES-induced impairments. Furthermore, we discuss the possible mechanisms involved in the beneficial effects of nutrition on the brain after ES, including neuroinflammation, oxidative stress, hypothalamus-pituitary-adrenal axis regulation and the microbiome-gut-brain axis. Lastly, we highlight the critical gaps in our current knowledge and make recommendations for future research to move the field forward.

Coconut oil supplementation during development reduces brain excitability in adult rats nourished and overnourished in lactation

INTRODUCTION

Coconut oil has been considered as a therapeutic alternative in several pathologies, but there is limited information regarding its effects on brain functioning.

OBJECTIVE

This study analyzed whether early virgin coconut oil (VCO) supplementation interferes with electrical activity of the adult rat brain and its lipid peroxidation. Moreover, it investigated whether the putative effect on brain electrophysiology could be affected by overnutrition occurring during lactation, and/or by environmental enrichment (EE). Electrophysiology was measured through cortical spreading depression (CSD), a phenomenon related to brain excitability.

METHODS

Wistar rats were suckled in litters of either nine or three pups, forming nourished (N) or overnourished (ON) groups, respectively. Between the 7th and 30th days of life, half of the animals in each group received VCO (10 mg kg^-1 d^-1; by gavage). The other half received an equivalent amount of vehicle (V, 0.009% cremophor). On day 36, animals from both groups were subjected to EE for 4 weeks. At 105 ± 15 days of life, each animal was subjected to CSD recordings and lipid peroxidation analyses.

RESULTS

Overnutrition during lactation enhanced body and brain weights. VCO decelerated the CSD propagation velocity (control - 3.57 ± 0.23 mm min^-1versus VCO - 3.27 ± 0.18 mm min^-1; p < 0.001), regardless of whether subjected to overnourishment or EE exposure. Neither VCO nor EE modified the cerebral lipid peroxidation (p > 0.05).

CONCLUSION

VCO supplementation impaired the spreading of CSD, indicating reduction of brain excitability. VCO effects occurred regardless of the nutritional state during lactation.

Can coconut oil and treadmill exercise during the critical period of brain development ameliorate stress-related effects on anxiety-like behavior and episodic-like memory in young rats?

Virgin coconut oil (CO) and treadmill exercise have been reported to improve memory performance in young rats.

Does stress elicit depression? Evidence from clinical and preclinical studies

Exposure to stressful situations may induce or deteriorate an already existing depression. Stress-related depression can be elicited at an adolescent/adult age but evidence also shows that early adverse experiences even at the fetal stage may predispose the offspring for later development of depression. The hypothalamus-pituitary-adrenal axis (HPA-axis) plays a key role in regulating the stress response and dysregulation in the system has been linked to depression both in humans and in animal models. This chapter critically reviews clinical and preclinical findings that may explain how stress can cause depression, including HPA-axis changes and alterations beyond the HPA-axis. As stress does not elicit depression in the majority of the population, this motivated research to focus on understanding the biology underlying resilient versus sensitive subjects. Animal models of depression have contributed to a deeper understanding of these mechanisms. Findings from these models will be presented.

Peripheral biomarkers in animal models of major depressive disorder

Investigations of preclinical biomarkers for major depressive disorder (MDD) encompass the quantification of proteins, peptides, mRNAs, or small molecules in blood or urine of animal models. Most studies aim at characterising the animal model by including the assessment of analytes or hormones affected in depressive patients. The ultimate objective is to validate the model to better understand the neurobiological basis of MDD. Stress hormones or inflammation-related analytes associated with MDD are frequently measured. In contrast, other investigators evaluate peripheral analytes in preclinical models to translate the results in clinical settings afterwards. Large-scale, hypothesis-free studies are performed in MDD models to identify candidate biomarkers. Other studies wish to propose new targets for drug discovery. Animal models endowed with predictive validity are investigated, and the assessment of peripheral analytes, such as stress hormones or immune molecules, is comprised to increase the confidence in the target. Finally, since the mechanism of action of antidepressants is incompletely understood, studies investigating molecular alterations associated with antidepressant treatment may include peripheral analyte levels. In conclusion, preclinical biomarker studies aid the identification of new candidate analytes to be tested in clinical trials. They also increase our understanding of MDD pathophysiology and help to identify new pharmacological targets.

Fish oil as a management component for mood disorders - an evolving signal

PURPOSE OF REVIEW

To overview the theoretical relevance of omega-3 and omega-6 fatty acids in the cause of mood disorders, and focus on evaluating the potential therapeutic role of omega-3 fatty acids.

RECENT FINDINGS

Numerous studies have documented low omega-3 fatty acid levels in those with depressive disorders, and there are plausible biological explanations as to why reduced omega-3 status may predispose to mood disorders as well as to a range of other conditions. Although early studies evaluating the role of omega-3 preparations as treatments of depression were generally positive, the rate of negative or nondifferential studies has increased in recent years. Recent meta-analyses provide an explanation in suggesting that docosahexaenoic acid-weighted preparations may be ineffective while finding support for eicosapentaenoic acid (EPA)-weighted preparations.

SUMMARY

There is sufficient indicative data favouring EPA-weighted omega-3 supplementation for those with a depressive mood disorder, particular when fish oil is viewed by patients as 'natural,' it has few side effects and is neuroprotective. Recent meta-analyses inform us that intervention studies should focus on EPA-weighted preparations.