Short-term neuronal effects of fumonisin B1 on neuronal activity in rodents

Fumonisin B1 neurotoxicity: Preclinical evidence, biochemical mechanisms and therapeutic strategies

The neurotoxic effects of fungal toxins in both humans and animals have been well documented. Fumonisin B1 (FB1), a mycotoxin produced by fungi of the Fusarium species, is the most toxic fumonisin variant whose neurotoxic effect is still being elucidated. This review highlights the biochemical aspects of FB1 neurotoxicity, such as its mechanisms of action as well as therapeutic strategies. Both in vitro and in vivo studies have demonstrated that alteration in sphingolipid metabolism is a major event in FB-induced neurotoxicity. Studies have also shown that neurotoxicity due to FB1 involves dysregulation of several biochemical events in the brain, such as induction of oxidative stress and inflammation, mitochondrial dysfunction and associated programmed cell death, inhibition of acetylcholinesterase and alteration of neurotransmitter levels, decreased activity of Na+K+ ATPase, as well as disruption of blood-brain barrier. This review highlights the potential public health effects of FB1-induced neurotoxicity and the need to limit human and animal exposure to FB1in order to prevent its neurotoxic effect. Moreover, it is hoped that this review would stimulate studies aimed at filling the current research gaps such as delineating the effect of FB1 on the blood-brain barrier and appropriate therapies for neurotoxicity caused by FB1.

Fumonisin distorts the cellular membrane lipid profile: A mechanistic insight

Monitoring modifications in membrane lipids in association with external stimuli/agents, including fumonisins (FUMs), is a widely employed approach to assess cellular metabolic response/status. FUMs are prevalent fusariotoxins worldwide that have diverse structures with varying toxicity across species; nevertheless, they can induce metabolic disturbances and disease, including cancer. The capacity of FUMs to disrupt membrane lipids, demonstrated across numerous species and organs/tissues, is ascribed to a multitude of factors/events, which range from direct to indirect effects. Certain events are well established, whereas the potential consequences of others remain speculative. The most notable effect is their resemblance to sphingoid bases, which impacts the synthesis of ceramides leading to numerous changes in lipids' composition that are not limited to sphingolipids' composition of the membranes. The next plausible scenario involves the induction of oxidative stress, which is considered an indirect/secondary effect of FUMs. Additional modes of action include modifications of enzyme activities and nuclear signals related to lipid metabolism, although these are likely not yet fully comprehended. This review provides in-depth insight into the current state of these events and their potential mechanistic actions in modifying membrane lipids, with a focus on long-chain fatty acids. This paper also presents a detailed description of the reported modifications to membrane lipids by FUMs.

Involvement of Autophagy and Oxidative Stress-Mediated DNA Hypomethylation in Transgenerational Nephrotoxicity Induced in Rats by the Mycotoxin Fumonisin B1

Fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, is one of the most common pollutants in natural foods and agricultural crops. It can cause chronic and severe health issues in humans and animals. The aim of this study was to evaluate the transgenerational effects of FB1 exposure on the structure and function of the kidneys in offspring. Virgin female Wistar rats were randomly divided into three groups: group one (control) received sterile water, and groups two and three were intragastrically administered low (20 mg/kg) and high (50 mg/kg) doses of FB1, respectively, from day 6 of pregnancy until delivery. Our results showed that exposure to either dose of FB1 caused histopathological changes, such as atrophy, hypercellularity, hemorrhage, calcification, and a decrease in the glomerular diameter, in both the first and second generations. The levels of the antioxidant markers glutathione, glutathione S-transferase, and catalase significantly decreased, while malondialdehyde levels increased. Moreover, autophagy was induced, as immunofluorescence analysis revealed that LC-3 protein expression was significantly increased in both generations after exposure to either dose of FB1. However, a significant decrease in methyltransferase (DNMT3) protein expression was observed in the first generation in both treatment groups (20 mg/kg and 50 mg/kg), indicating a decrease in DNA methylation as a result of early-life exposure to FB1. Interestingly, global hypomethylation was also observed in the second generation in both treatment groups despite the fact that the mothers of these rats were not exposed to FB1. Thus, early-life exposure to FB1 induced nephrotoxicity in offspring of the first and second generations. The mechanisms of action underlying this transgenerational effect may include oxidative stress, autophagy, and DNA hypomethylation.

Interaction of Fumonisin B1, N-Palmitoyl-Fumonisin B1, 5-O-Palmitoyl-Fumonisin B1, and Fumonisin B4 Mycotoxins with Human Serum Albumin and Their Toxic Impacts on Zebrafish Embryos

Fumonisins are frequent food contaminants. The high exposure to fumonisins can cause harmful effects in humans and animals. Fumonisin B1 (FB1) is the most typical member of this group; however, the occurrence of several other derivatives has been reported. Acylated metabolites of FB1 have also been described as possible food contaminants, and the very limited data available suggest their significantly higher toxicity compared to FB1. Furthermore, the physicochemical and toxicokinetic properties (e.g., albumin binding) of acyl-FB1 derivatives may show large differences compared to the parent mycotoxin. Therefore, we tested the interactions of FB1, N-palmitoyl-FB1 (N-pal-FB1), 5-O-palmitoyl-FB1 (5-O-pal-FB1), and fumonisin B4 (FB4) with human serum albumin as well as the toxic effects of these mycotoxins on zebrafish embryos were examined. Based on our results, the most important observations and conclusions are the following: (1) FB1 and FB4 bind to albumin with low affinity, while palmitoyl-FB1 derivatives form highly stable complexes with the protein. (2) N-pal-FB1 and 5-O-pal-FB1 likely occupy more high-affinity binding sites on albumin. (3) Among the mycotoxins tested, N-pal-FB1 showed the most toxic effects on zebrafish, followed by 5-O-pal-FB1, FB4, and FB1. (4) Our study provides the first in vivo toxicity data regarding N-pal-FB1, 5-O-pal-FB1, and FB4.

The natural occurrence, toxicity mechanisms and management strategies of Fumonisin B1：A review

Fumonisin B1 (FB1) contaminates various crops, causing huge losses to agriculture and livestock worldwide. This review summarizes the occurrence regularity, toxicity, toxic mechanisms and management strategies of FB1. Specifically, FB1 contamination is particularly serious in developing countries, humid and hot regions. FB1 exposure can produce different toxic effects on the nervous system, respiratory system, digestive system and reproductive system. Furthermore, FB1 can also cause systemic immunotoxicity. The mechanism of toxic effects of FB1 is to interfere with the normal pathway of sphingolipid de novo biosynthesis by acting as a competitive inhibitor of ceramide synthase. Meanwhile, the toxic products of sphingolipid metabolic disorders can cause oxidative stress and apoptosis. FB1 also often causes feed contamination by mixing with other mycotoxins, and then exerts combined toxicity. For detection, lateral flow dipstick technology and enzyme linked immunosorbent assay are widely used in the detection of FB1 in commercial feeds, while mainstream detection methods such as high performance liquid chromatography and liquid chromatography-mass spectrometry are widely used in the laboratory theoretical study of FB1. For purification means of FB1, some natural plant extracts (such as Zingiber officinale and Litsea Cubeba essential oil) and their active compounds have been proved to inhibit the toxic effects of FB1 and protect livestock due to their antifungal and antioxidant effects. Natural plant extract has the advantages of high efficiency, low cost and no contamination residue. This review can provide information for comprehensive understanding of FB1, and provide reference for formulating reasonable treatment and management strategies in livestock production.

Abnormal neurotransmission of GABA and serotonin in Caenorhabditis elegans induced by Fumonisin B1

Fumonisin B1 (FB1) is a neurodegenerative mycotoxin synthesized by Fusarium spp., but the potential neurobehavioral toxicity effects in organisms have not been characterized clearly. Caenorhabditis elegans (C. elegans) has emerged as a promising model organism for neurotoxicological studies due to characteristics such as well-functioning nervous system and rich behavioral phenotypes. To investigate whether FB1 has neurobehavioral toxicity effects on C. elegans, the motor behavior, neuronal structure, neurotransmitter content, and gene expression related with neurotransmission of C. elegans were determined after exposed to 20-200 μg/mL FB1 for 24 h and 48 h, respectively. Results showed that FB1 caused behavioral defects, including body bends, head thrashes, crawling distance, mean speed, mean amplitude, mean wavelength, foraging behavior, and chemotaxis learning ability in a dose-, and time-dependent manner. In addition, when C. elegans was exposed to FB1 at a concentration of 200 μg/mL for 24 h and above 100 μg/mL for 48 h, the GABAergic and serotonergic neurons were damaged, but no effect on dopaminergic, glutamatergic, and cholinergic neurons. The relative content of GABA and serotonin decreased significantly. Furthermore, abnormal expression of mRNA levels associated with GABA and serotonin were found in nematodes treated with FB1, such as unc-30, unc-47, unc-49, exp-1, mod-5, cat-1, and tph-1. The neurobehavioral toxicity effect of FB1 may be mediated by abnormal neurotransmission of GABA and serotonin. This study provides useful information for understanding the neurotoxicity of FB1.

Effectiveness of beetroot extract in SH-SY5Y neuronal cell protection against Fumonisin B1, Ochratoxin A and its combination

Fumonisin B1 (FB1) and ochratoxin A (OTA) are fungal metabolites of worldwide concern because of their effect on human and animal health, as both have been classified by IARC as possible carcinogens (Group 2B). Beetroot is a source of dietary fiber, folic acid, and vitamin C, and some studies have demonstrated their antioxidant activity. Therefore, this work presents the cytoprotective effect of beetroot extract (BRE) on a neuroblastoma cell line (SH-SY5Y cells) exposed to FB1, OTA, and its combination. Cytotoxicity was studied by the MTT ([3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, for 24 h and 48 h. Simultaneous treatment and pre-treatment strategies were tested with 1:512-1:2 and 1:0 dilutions of BRE, with a concentration range from 0.4 to 100 μM of FB1 and from 0.19 to 50 μM of OTA. IC₅₀ values of 5.8 μM and 9.1 μM at 24 h and 48 h, respectively were obtained for OTA while no cytotoxic effect was detected at the concentrations tested for FB1. Cytoprotection with increased viability was obtained when the simultaneous BRE + OTA strategy was performed. Finally, better protection was observed in the pretreatment strategy in which cells were exposed 24 h previously to BRE, compared to that shown in the simultaneous assay.