Changes in serum brain-derived neurotrophic factor following supplementation of omega 3 fatty acids: A systematic review and Meta-Regression analysis

BACKGROUND & AIMS

This study aimed to comprehensively investigate the effects of omega 3 supplementation on BDNF.

METHODS

Original databases were searched using standard keywords to identify all controlled trials that investigating the BDNF effects of omega 3 supplementation. Pooled weighted mean difference and 95% confidence intervals were achieved by random-effects model analysis for the best estimation of outcomes.

RESULTS

According to the results of a random-effects meta-analysis, omega 3 supplementation significantly raised BDNF levels compared to the control group (pooled WMD of 1.01 μmol/L; 95% confidence interval [CI] 0.35 to 1.67; P = 0.003) and this increase was even more pronounced for interventions >10 weeks and doses ≤1500 mg/day. Additionally, in individuals under 50 years of age, a greater increase in the effects of omega-3 supplements on this brain factor was observed.

CONCLUSIONS

The present comprehensive review and meta-regression analysis generally showed that omega-3 supplementation can statistically significantly increase BDNF levels.

Impact of SARS-CoV-2 on Host Factors Involved in Mental Disorders

COVID-19, caused by SARS-CoV-2, is a systemic illness due to its multiorgan effects in patients. The disease has a detrimental impact on respiratory and cardiovascular systems. One early symptom of infection is anosmia or lack of smell; this implicates the involvement of the olfactory bulb in COVID-19 disease and provides a route into the central nervous system. However, little is known about how SARS-CoV-2 affects neurological or psychological symptoms. SARS-CoV-2 exploits host receptors that converge on pathways that impact psychological symptoms. This systemic review discusses the ways involved by coronavirus infection and their impact on mental health disorders. We begin by briefly introducing the history of coronaviruses, followed by an overview of the essential proteins to viral entry. Then, we discuss the downstream effects of viral entry on host proteins. Finally, we review the literature on host factors that are known to play critical roles in neuropsychiatric symptoms and mental diseases and discuss how COVID-19 could impact mental health globally. Our review details the host factors and pathways involved in the cellular mechanisms, such as systemic inflammation, that play a significant role in the development of neuropsychological symptoms stemming from COVID-19 infection.

Prevention of streptozotocin‑induced Neuro‑2a cell death by C8‑B4 microglia transformed with repetitive low‑dose lipopolysaccharide

Diabetes‑associated neuronal dysfunction (DAND) is one of the serious complications of diabetes, but there is currently no remedy for it. Streptozotocin [2‑deoxy‑2‑(3‑methy1‑3‑nitrosoureido) D‑glucopyranose; STZ] is one of the most well‑established diabetes inducers and has been used in vivo and in vitro DAND models. The aim of the present study was to demonstrate that C8‑B4 microglia transformed by the stimulus of repetitive low‑dose lipopolysaccharide (LPSx3‑microglia) prevent STZ‑induced Neuro‑2a neuronal cell death in vitro. The ELISA results showed that neurotrophin‑4/5 (NT‑4/5) secretion was promoted in LPSx3‑microglia and the cell viability assay with trypan blue staining revealed that the culture supernatant of LPSx3‑microglia prevented STZ‑induced neuronal cell death. In addition, reverse transcription‑quantitative PCR showed that neurons treated with the culture supernatant of LPSx3‑microglia promoted the gene expression of B‑cell lymphoma‑extra large and glucose‑dependent insulinotropic polypeptide receptor. Furthermore, the inhibition of tyrosine kinase receptor B, a receptor of NT‑4/5, suppressed the neuroprotective effect of LPSx3‑microglia. Taken together, the present study demonstrated that LPSx3‑microglia prevent STZ‑induced neuronal death and that NT‑4/5 may be involved in the neuroprotective mechanism of LPSx3‑microglia.

Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties?

The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.

Effects of nutritional interventions on BDNF concentrations in humans: a systematic review

Objectives: Brain-derived neurotrophic factor (BDNF) plays an essential role in brain and metabolic health. The fact that higher concentrations are associated with improved cognitive performance has resulted in numerous intervention trials that aim at elevating BDNF levels. This systematic review provides an overview of the relation between various nutritional factors and BDNF concentrations in controlled human intervention studies. Methods: A systematic search in May 2020 identified 48 articles that examined the effects of dietary patterns or foods (n = 3), diets based on energy intake (n = 7), vitamins and minerals (n = 7), polyphenols (n = 11), long-chain omega-3 polyunsaturated fatty acids (n = 5), probiotics (n = 8), and miscellaneous food supplements (n = 7). Results: In particular, studies with dietary patterns or foods showed increased peripheral BDNF concentrations. There are also strong indications that polyphenols tend to have a positive effect on BDNF concentrations. Four of the 11 included studies with a polyphenol intervention showed a significant increase in BDNF concentrations, one study showed an increase but this was not statistically analyzed, and two studies showed a trend to an increase. Discussion: The two polyphenol classes, phenolic acids, and other phenolic compounds were responsible for the significant effects. No clear effect was found for the other dietary factors, which might also be related to whether serum or plasma was used for BDNF analysis. More work is needed to understand the relation between peripheral and central BDNF concentrations.

TrkB-Mediated Neuroprotective and Antihypoxic Properties of Brain-Derived Neurotrophic Factor

The neuroprotective and antihypoxic effects of brain-derived neurotrophic factor (BDNF) on dissociated hippocampal cultures in a hypoxia model were investigated. These experiments demonstrate that 10 minutes of normobaric hypoxia increased the number of dead cells in primary culture, whereas a preventive application of BDNF increased the number of viable cells. Spontaneous bioelectrical and calcium activity in neural networks was analyzed using multielectrode arrays and functional intravital calcium imaging. The results indicate that BDNF affects the functional parameters of neuronal networks in dissociated hippocampal cultures over the 7-day posthypoxic period. In addition, the effects of k252a, an antagonist of tropomyosin-related kinase B (TrkB), on functional bioelectrical activity during and after acute hypoxia were investigated. It was shown that the protective effects of BDNF are associated with binding to the TrkB receptor. Finally, intravital fluorescent mRNA probes were used to study the role of NF-κB1 in the protective effects of BDNF. Our experiments revealed that BDNF application stimulates NF-κB1 mRNA synthesis in primary dissociated hippocampal cells under normal conditions but not in hypoxic state.

Oscillations in a neurite growth model with extracellular feedback

We consider the influence of extracellular signalling on neurite elongation in a model of neurite growth mediated by building proteins (e.g., tubulin). The tubulin production dynamics were supplied by a function describing the influence of extracellular signalling, which can promote or depress neurite elongation. We found that this extracellular feedback could generate neurite length oscillations consisting of a periodic sequence of elongations and retractions. The oscillations prevent further outgrowth of the neurite, which becomes trapped in the non-uniform extracellular field. We analysed the characteristics of the elongation process for different distributions of attracting and repelling sources of the extracellular signalling molecules. The model predicts three different scenarios of neurite development in the extracellular field, including monotonic and oscillatory outgrowth, localised limit cycle oscillations and complete growth depression.