The supplementation of a high dose of fish oil during pregnancy and lactation led to an elevation in Mfsd2a expression without any changes in docosahexaenoic acid levels in the retina of healthy 2-month-old mouse offspring.

Introduction: During fetal development, the proper development of neural and visual systems relies on the maternal supplementation of omega-3 fatty acids through placental transfer. Pregnant women are strongly advised to augment their diet with additional sources of omega-3, such as fish oil (FO). This supplementation has been linked to a reduced risk of preterm birth, pre-eclampsia, and perinatal depression. Recently, higher doses of omega-3 supplementation have been recommended for pregnant women. Considering that omega-3 fatty acids, particularly docosahexaenoic acid (DHA), play a crucial role in maintaining the delicate homeostasis required for the proper functioning of the retina and photoreceptors the effects of high-dose fish oil (FO) supplementation during pregnancy and lactation on the retina and retinal pigmented epithelium (RPE) in healthy offspring warrant better understanding. Methods: The fatty acid content and the changes in the expression of the genes regulating cholesterol homeostasis and DHA transport in the retina and RPE were evaluated following the high-dose FO supplementation. Results: Our study demonstrated that despite the high-dose FO treatment during pregnancy and lactation, the rigorous DHA homeostasis in the retina and RPE of the two-month-old offspring remained balanced. Another significant finding of this study is the increase in the expression levels of major facilitator superfamily domain-containing protein (Mfsd2a), a primary DHA transporter. Mfsd2a also serves as a major regulator of transcytosis during development, and a reduction in Mfsd2a levels poses a major risk for the development of leaky blood vessels. Conclusion: Impairment of the blood-retinal barrier (BRB) is associated with the development of numerous ocular diseases, and a better understanding of how to manipulate transcytosis in the BRB during development can enhance drug delivery through the BRB or contribute to the repair of central nervous system (CNS) barriers.

Fatty acids as biomodulators of Piezo1 mediated glial mechanosensitivity in Alzheimer's disease.

The brain is the softest organ in the body, and any change in the mechanical properties of the tissue induces the activation of glial cells, astrocytes and microglia. Amyloid plaques, one of the main pathological features of Alzheimer's disease (AD), are substantially harder than the surrounding brain tissue and can activate astrocytes and microglia resulting in the glial engulfment of plaques. Durotaxis, a migratory preference towards stiffer tissue, is prompting microglia to form a mechanical barrier around plaques reducing amyloid ß (Aß) induced neurotoxicity. Mechanoreceptors are highly expressed in the brain, particularly in microglia. The large increase in the expression of the mechanoreceptor Piezo1 was observed in the brains from AD animal models and AD patients in plaque encompassing glia. Importantly, Piezo1 function is regulated via force-from-lipids through the lipid composition of the membrane and membranous incorporation of polyunsaturated fatty acids (PUFAs) can affect the function of Piezo1 altering mechanosensitive properties of the cell. On the other hand, PUFAs dietary supplementation can alter microglial polarization, the envelopment of amyloid plaques, and immune response and Piezo1 activity was implicated in the similar modulations of microglia behavior. Finally, PUFAs treatment is currently in use in medical trials as the therapy for sickle cell anemia, a disease linked with the mutations in Piezo1. Further studies are needed to elucidate the connection between PUFAs, Piezo1 expression, and microglia behavior in the AD brain. These findings could open new possibilities in harnessing microglia in AD and in developing novel therapeutic strategies.

Short-term fish oil supplementation applied in presymptomatic stage of Alzheimer's disease enhances microglial/macrophage barrier and prevents neuritic dystrophy in parietal cortex of 5xFAD mouse model.

Dystrophic neurites and activated microglia are one of the main neuropathological characteristics of Alzheimer's disease (AD). Although the use of supplements with omega-3 fatty acids has been associated with reduced risk and lessened AD pathology, it still remains elusive whether such a treatment could affect dystrophic neurites (DNs) formation and microglia/macrophage behavior in the early phase of disease. We analyzed the effects of short-term (3 weeks) fish oil supplementation on DNs formation, tau hyperphosphorylation, Amyloid-beta peptide 1-42 (Aß42) levels and microglial/macrophage response to AD pathology in the parietal cortex of 4-month-old 5xFAD mice, a mouse model of AD. The present study shows for the first time that short-term FO supplementation applied in presymptomatic stage of AD, alters the behaviour of microglia/macrophages prompting them to establish a physical barrier around amyloid plaques. This barrier significantly suppresses DNs formation through the reduction of both Aß content and tau hyperphosphorylation. Moreover, the short-term FO treatment neither suppresses inflammation nor enhances phagocytic properties of microglia/macrophages in the response to Aß pathology, the effects most commonly attributed to the fish oil supplementation. Our findings suggest that fish oil consumption may play an important role in modulating microglial/macrophage response and ameliorating the AD pathology in presymptomatic stage of Alzheimer's disease.

Short-Term Fish Oil Treatment Changes the Composition of Phospholipids While Not Affecting the Expression of Mfsd2a Omega-3 Transporter in the Brain and Liver of the 5xFAD Mouse Model of Alzheimer's Disease.

Long-term fish oil (FO) supplementation is able to improve Alzheimer's disease (AD) pathology. We aimed to determine the impact of short-term fish oil (FO) intake on phospholipids composition and plaque pathology in 5xFAD mice, a widely used animal model of AD. A 3-week-long FO supplementation administered at 3 months of age decreased the number of dense core plaques in the 5xFAD cortex and changed phospholipids in the livers and brains of wild-type (Wt) and 5xFAD mice. Livers of both genotypes responded by increase of n-3 and reciprocal decrease of n-6 fatty acids. In Wt brains, FO supplementation induced elevation of n-3 fatty acids and subsequent enhancement of n-6/n-3 ratio. However, in 5xFAD brains the improved n-6/n-3 ratio was mainly due to FO-induced decrease in arachidonic and adrenic n-6 fatty acids. Also, brain and liver abundance of n-3 fatty acids were strongly correlated in Wts, oppositely to 5xFADs where significant brain-liver correlation exists only for n-6 fatty acids. Expression of omega-3 transporter Mfs2a remained unchanged after FO supplementation. We have demonstrated that even a short-term FO intake improves the phospholipid composition and has a significant effect on plaque burden in 5xFAD brains when applied in early stages of AD pathology.