Modification of energy balance induced by the food contaminant T-2 toxin: a multimodal gut-to-brain connection

"Three-in-One" Multifunctional Hollow Nanocages with Colorimetric Photothermal Catalytic Activity for Enhancing Sensitivity in Biosensing

Immunochromatographic assays (ICAs) have been widely used in the field detection of mycotoxin contaminants. Nevertheless, the lack of multisignal readout capability and the ability of signaling tags to maintain their biological activity while efficiently loading antibodies remain a great challenge in satisfying diverse testing demands. Herein, we proposed a novel three-in-one multifunctional hollow vanadium nanomicrosphere (high brightness-catalytic-photothermal properties)-mediated triple-readout ICA (VHMS-ICA) for sensitive detection of T-2. As the key to this biosensing strategy, vanadium was used as the catalytic-photothermal characterization center, and natural polyphenols were utilized as the bridging ligands for coupling with the antibody while self-assembling with formaldehyde cross-linking into a hollow nanocage-like structure, which offers the possibility of realizing a three-signal readout strategy and improving the coupling efficiency to the antibody while preserving its biological activity. The constructed sensors showed a detection limit (LOD) of 2 pg/mL for T-2, which was about 345-fold higher than that of conventional gold nanoparticle-based ICA (0.596 ng/mL). As anticipated, the detection range of VHMS-ICA was extended about 8-fold compared with the colorimetric signal alone. Ultimately, the proposed immunosensor performed well in maize and oat samples, with satisfactory recoveries. Owing to the synergistic and complementary interactions between distinct signaling modes, the establishment of multimodal immunosensors with multifunctional tags is an efficient strategy to satisfy diversified detection demands.

Selenomethionine Antagonized microRNAs Involved in Apoptosis of Rat Articular Cartilage Induced by T-2 Toxin

T-2 toxin and selenium deficiency are considered important etiologies of Kashin-Beck disease (KBD), although the exact mechanism is still unclear. To identify differentially expressed microRNAs (DE-miRNAs) in the articular cartilage of rats exposed to T-2 toxin and selenomethionine (SeMet) supplementation, thirty-six 4-week-old Sprague Dawley rats were divided into a control group (gavaged with 4% anhydrous ethanol), a T-2 group (gavaged with 100 ng/g·bw/day T-2 toxin), and a T-2 + SeMet group (gavaged with 100 ng/g·bw/day T-2 toxin and 0.5 mg/kg·bw/day SeMet), respectively. Toluidine blue staining was performed to detect the pathological changes of articular cartilage. Three rats per group were randomly selected for high-throughput sequencing of articular cartilage. Target genes of DE-miRNAs were predicted using miRanda and RNAhybrid databases, and the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway were enriched. The network map of miRNA-target genes was constructed using Cytoscape software. The expression profiles of miRNAs associated with KBD were obtained from the Gene Expression Omnibus database. Additionally, the DE-miRNAs were selected for real-time quantitative PCR (RT-qPCR) verification. Toluidine blue staining demonstrated that T-2 toxin damaged articular cartilage and SeMet effectively alleviated articular cartilage lesions. A total of 50 DE-miRNAs (28 upregulated and 22 downregulated) in the T-2 group vs. the control group, 18 DE-miRNAs (6 upregulated and 12 downregulated) in the T-2 + SeMet group vs. the control group, and 25 DE-miRNAs (5 upregulated and 20 downregulated) in the T-2 + SeMet group vs. the T-2 group were identified. Enrichment analysis showed the target genes of DE-miRNAs were associated with apoptosis, and in the MAPK and TGF-β signaling pathways in the T-2 group vs. the control group. However, the pathway of apoptosis was not significant in the T-2 + SeMet group vs. the control group. These results indicated that T-2 toxin induced apoptosis, whereas SeMet supplementation antagonized apoptosis. Apoptosis and autophagy occurred simultaneously in the T-2 + SeMet group vs. T-2 group, and autophagy may inhibit apoptosis to protect cartilage. Compared with the GSE186593 dataset, the evidence of miR-133a-3p involved in apoptosis was more abundant. The results of RT-qPCR validation were consistent with RNA sequencing results. Our findings suggested that apoptosis was involved in articular cartilage lesions induced by T-2 toxin, whereas SeMet supplementation antagonized apoptosis, and that miR-133a-3p most probably played a central role in the apoptosis process.

Effects of T-2 toxin on growth performance, feather quality, tibia development and blood parameters in Yangzhou goslings

T-2 toxin is a dangerous natural pollutant and widely exists in animal feed, often causing toxic damage to poultry, such as slow growth and development, immunosuppression, and death. Although geese are considered the most sensitive poultry to T-2 toxin, the exact damage caused by T-2 toxin to geese is elusive. In the present study, a total of forty two 1-day-old healthy Yangzhou male goslings were randomly allotted seven diets contaminated with 0, 0.2, 0.4, 0.6, 0.8, 1.0, or 2.0 mg/kg T-2 toxin for 21 d, and the effects of T-2 toxin exposure on growth performance, feather quality, tibia development, and blood parameters were investigated. The results showed that T-2 toxin exposure significantly inhibited feed intake, body weight gain, shank length growth, and organ development (e.g., ileum, cecum, liver, spleen, bursa, and tibia) in a dose-dependent manner. In addition, the more serious feathering abnormalities and feather damage were observed in goslings exposed to a high dose of T-2 toxin (0.8, 1.0, and 2.0 mg/kg), which were mainly sparsely covered with short, dry, rough, curly, and gloss-free feathers on the back. We also found that hypertrophic chondrocytes of the tibial growth plate exhibited abnormal morphology and nuclear consolidation or loss, accompanied by necrosis and excessive apoptosis under 2.0 mg/kg T-2 toxin exposure. Moreover, 2.0 mg/kg T-2 toxin exposure triggered erythropenia, thrombocytosis, alanine aminotransferase, and aspartate aminotransferase activity, as well as high blood urea nitrogen, uric acid, and lactic dehydrogenase levels. Collectively, these data indicate that T-2 toxin had an adverse effect on the growth performance, feather quality, and tibia development, and caused liver and kidney damage and abnormal blood parameters in Yangzhou goslings, providing crucial information toward the prevention and control of T-2 toxin contamination in poultry feed.

Stressful Effects of T-2 Metabolites and Defense Capability of HepG2 Cells

The T-2 toxin (T-2), a mycotoxin produced by several species of Fusarium which belongs to group A of trichothecenes, is rapidly metabolized, and its main metabolites are HT-2, Neosolaniol (Neo), T2-triol and T2-tetraol. In this work, the antioxidant defense system of HepG2 cells against oxidative stress induced by T-2 and its metabolites was evaluated. The results obtained demonstrated that there is an overall decrease in glutathione (GSH) levels after all mycotoxins exposure. Moreover, the GSH levels and the enzymatic activities related to GSH (GPx and GST) increased with NAC pre-treatment (glutathione precursor) and decreased with BSO pre-treatment (glutathione inhibitor). The GPx activity is increased by T2-tetraol. The GST activity increased after T-2 and T2-triol exposure; however, T2-tetraol decreased its activity. Furthermore, CAT activity increased after T-2 and T2-triol; nevertheless, Neo decreased its activity. Finally, SOD activity is increased by all mycotoxins, except after T-2 exposure. So, the damage associated with oxidative stress by T-2 and its metabolites is relieved by the antioxidant enzymes system on HepG2 cells.

Assessment of information as regards the toxicity of T‐2 and HT‐2 toxin for ruminants

In 2011, the EFSA Panel on Contaminants in the Food Chain (CONTAM) adopted a Scientific Opinion on the risks for animal health related to the presence of T‐2 (T2) and HT‐2 (HT2) toxin in food and feed. No observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) were derived for different animal species. In ruminants a LOAEL was established for the sum of T2 and HT2 of 0.3 mg/kg body weight (bw) per day, based on studies with calves and lambs. The CONTAM Panel noted that the effects observed in nutritionally challenged heifers and ewes give rise to the assumption that rumen detoxification of T2 may not always be complete and therefore effective to prevent adverse effects in ruminants. However, the limited data on the effects of T2 on adult ruminants did not allow a conclusion. The European Commission requested EFSA to review the information regarding the toxicity of T2 and HT2 for ruminants and to revise, if necessary, the established Reference Point (RP). Adverse effect levels of 0.001 and 0.01 mg T2/kg bw per day for, respectively, sheep and cows, were derived from case studies, estimated to correspond to feed concentrations of 0.035 mg T2/kg for sheep and 0.6 mg T2/kg for cows. RPs for adverse animal health effects of 0.01 mg/kg feed for sheep and 0.2 mg/kg feed for cows were established. For goats, the RP for cows was selected, in the absence of data that they are more sensitive. Based on mean exposure estimates performed in the previous Opinion, the risk of adverse health effects of feeds containing T2 and HT2 was considered a concern for lactating sheep. For milking goats, a comparison performed between dietary exposure and the RP derived for cows, indicates a potential risk for adverse health effects. For dairy cows and fattening beef, the risk is considered low.

Protective Effect of Selenomethionine on T-2 Toxin-Induced Rabbit Immunotoxicity

T-2 toxin is a trichothecene mycotoxin produced by fusarium species, which is mainly prevalent in grain and livestock feed. One of the main effects of this toxin is immunodepression. Previous studies have shown that T-2 toxin can cause damage to immune organs and impaired immune function in animals. However, selenomethionine (SeMet) as an organic selenium source can not only promote the growth and development of the body but also effectively improve the body's immune function. In this study, rabbits were exposed to 0.4-mg/kg T-2 toxin, and abnormal blood routine indicators were found in the rabbits. HE staining also showed obvious lesions in the spleen and thymus tissue structures, accompanied by a large number of bleeding points. In addition, rabbits showed strong oxidative stress and inflammatory response after T-2 toxin action. 0.2 mg/kg, 0.4 mg/kg, and 0.6 mg/kg organic selenium were added to the feed. However, it was found that 0.2 mg/kg selenium can effectively improve the abnormal changes of blood routine and spleen and thymus tissue of rabbits. On the other hand, it can significantly increase the expression of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) in the spleen and thymus, and downregulate the expression of reactive oxygen species (ROS) and malondialdehyde (MDA). In addition, inflammatory factors interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in blood were also significantly inhibited; the expression of proliferating cell nuclear antigen (PCNA) in the spleen and thymus was also significantly increased after low-dose selenium treatment. Surprisingly, 0.4 mg/kg and 0.6 mg/kg of selenium did not effectively alleviate the immunotoxic effects caused by T-2 toxin, and cause damage to a certain extent. In summary, our results show that 0.2 mg/kg of SeMet can effectively alleviate the immunotoxicity caused by T-2 toxin. Selenium may protect rabbits from T-2 toxin by improving its antioxidant and anti-inflammatory capabilities.

T-2 Toxin-The Most Toxic Trichothecene Mycotoxin: Metabolism, Toxicity, and Decontamination Strategies

Among trichothecenes, T-2 toxin is the most toxic fungal secondary metabolite produced by different Fusarium species. Moreover, T-2 is the most common cause of poisoning that results from the consumption of contaminated cereal-based food and feed reported among humans and animals. The food and feed most contaminated with T-2 toxin is made from wheat, barley, rye, oats, and maize. After exposition or ingestion, T-2 is immediately absorbed from the alimentary tract or through the respiratory mucosal membranes and transported to the liver as a primary organ responsible for toxin's metabolism. Depending on the age, way of exposure, and dosage, intoxication manifests by vomiting, feed refusal, stomach necrosis, and skin irritation, which is rarely observed in case of mycotoxins intoxication. In order to eliminate T-2 toxin, various decontamination techniques have been found to mitigate the concentration of T-2 toxin in agricultural commodities. However, it is believed that 100% degradation of this toxin could be not possible. In this review, T-2 toxin toxicity, metabolism, and decontamination strategies are presented and discussed.

A fluorescence aptasensor for the sensitive detection of T-2 toxin based on FRET by adjusting the surface electric potentials of UCNPs and MIL-101

T-2 toxin is a class A trichothecene mycotoxin produced by Fusarium, which exhibits genotoxic, cytotoxic, and immunotoxic effects in animals and humans. In this study, we developed an aptasensor for the sensitive detection of T-2 toxin, which was based on fluorescence resonance energy transfer (FRET), and acted by adjusting the electric potential on the surface of upconversion nanoparticles (UCNPs) and MIL-101(Cr). In addition, it combined the excellent spectral properties of UCNPs with the good adsorption quenching abilities of metal organic frameworks (MOFs). Under the action of π-π stacking interactions, the UCNPs-aptamer was adsorbed onto the surface of MIL-101, leading to fluorescence quenching due to the occurrence of FRET. After the addition of T-2 toxin, owing to its selective binding to the UCNPs-aptamer, the UCNPs-aptamer moved away from MIL-101(Cr), resulting in fluorescence recovery. Moreover, the extent of fluorescence recovery was positively correlated with the concentration of T-2 toxin. The limit of detection (LOD) of this sensor was 0.087 ng mL^-1 (S/N = 3), and a good linear correlation was observed between the fluorescence intensity and the T-2 toxin concentration in the range of 0.1-100 ng mL^-1. Moreover, the recovery of this method was 97.52-109.53% for corn meal samples (relative standard deviation, RSD = 1.7-2.4%) and 90.81-100.02% for beer samples (RSD = 2.4-2.7%). By adjusting the surface electric potentials, the efficient fluorescence aptasensor combined the advantages of UCNPs and MIL-101(Cr) and allowed the first application of such a system in toxin detection, thereby indicating its potential food sample analysis and biochemical sensing.

Blockade of Glial Connexin 43 Hemichannels Reduces Food Intake

The metabolic syndrome, which comprises obesity and diabetes, is a major public health problem and the awareness of energy homeostasis control remains an important worldwide issue. The energy balance is finely regulated by the central nervous system (CNS), notably through neuronal networks, located in the hypothalamus and the dorsal vagal complex (DVC), which integrate nutritional, humoral and nervous information from the periphery. The glial cells’ contribution to these processes emerged few year ago. However, its underlying mechanism remains unclear. Glial connexin 43 hemichannels (Cx43 HCs) enable direct exchange with the extracellular space and can regulate neuronal network activity. In the present study, we sought to determine the possible involvement of glial Cx43 HCs in energy balance regulation. We here show that Cx43 is strongly expressed in the hypothalamus and DVC and is associated with glial cells. Remarkably, we observed a close apposition of Cx43 with synaptic elements in both the hypothalamus and DVC. Moreover, the expression of hypothalamic Cx43 mRNA and protein is modulated in response to fasting and diet-induced obesity. Functionally, we found that Cx43 HCs are largely open in the arcuate nucleus (ARC) from acute mice hypothalamic slices under basal condition, and significantly inhibited by TAT-GAP19, a mimetic peptide that specifically blocks Cx43 HCs activity. Moreover, intracerebroventricular (i.c.v.) TAT-GAP19 injection strongly decreased food intake, without further alteration of glycaemia, energy expenditures or locomotor activity. Using the immediate early gene c-Fos expression, we found that i.c.v. TAT-GAP19 injection induced neuronal activation in hypothalamic and brainstem nuclei dedicated to food intake regulation. Altogether, these results suggest a tonic delivery of orexigenic molecules associated with glial Cx43 HCs activity and a possible modulation of this tonus during fasting and obesity.

The neurotoxicity of trichothecenes T-2 toxin and deoxynivalenol (DON): Current status and future perspectives

During the last decade, the neurotoxicity of the trichothecenes T-2 toxin and deoxynivalenol (DON) has been a major concern, and many important findings have been reported on this topic. Through a summary of relevant research reports in recent years, we discuss the potential neurotoxic mechanisms of T-2 toxin and DON. In neuronal cells, T-2 toxin induces mitochondrial dysfunction and oxidative stress through a series of signalling pathways, including Nrf2/HO-1 and p53. This toxin crosses the blood-brain barrier (BBB) by altering permeability and induces oxidative stress responses, including ROS generation, lipid peroxidation, and protein carbonyl formation. Cellular metabolites (for example, HT-2 toxin) further promote neurotoxic effects. The type B trichothecene DON induces neuronal cell apoptosis via the MAPK and mitochondrial apoptosis pathways. This molecule induces inflammation of the central nervous system, increasing the expression of proinflammatory molecules. DON directly affects brain neurons and glial cells after passing through the BBB and affects the vitality and function of astrocytes and microglia. Exposure to trichothecenes alters brain dopamine levels, decreases ganglion area, and further induces brain damage. In this review, we mainly discuss the neurotoxicity of T-2 toxin and DON. However, our main goal was to reveal the potential mechanism(s) and offer new topics, including the potential of hypoxia-inducible factors, immune evasion, and exosomes, for future research in this context. This review should help elucidate the neurotoxic mechanism of trichothecenes and provides some potential inspiration for the follow-up study of neurotoxicity of mycotoxins.

Identification and Distribution of Novel Metabolites of Lolitrem B in Mice by High-Resolution Mass Spectrometry

Lolitrem B is the most potent indole-diterpene mycotoxin produced by Epichloë festucae var. lolii (termed LpTG-1), with severe intoxication cases reported in livestock. To date, there are no in vivo metabolism studies conducted for the mycotoxin. A mouse model assay established for assessing toxicity of indole-diterpenes was used to investigate metabolic products of lolitrem B. Mice were administered lolitrem B at 0.5 and 2.0 mg/kg body weight (b.wt) intraperitoneally before body and brain tissues were collected at 6 h and 24 h post-treatment. Samples were cryoground and subjected to a biphasic or monophasic extraction. The aqueous and lipophilic phases were analysed using liquid chromatography high-resolution mass spectrometry (LC–HRMS); data analysis was performed with Compound Discoverer™ software. A total of 10 novel phase I metabolic products were identified in the lipophilic phase and their distribution in the liver, kidney and various brain regions are described. The biotransformation products of lolitrem B were found to be present in low levels in the brain. Based on structure–activity postulations, six of these may contribute towards the protracted tremors exhibited by lolitrem B-exposed animals.

Phytochemicals and Gastrointestinal Cancer: Cellular Mechanisms and Effects to Change Cancer Progression

Gastrointestinal (GI) cancer is a prevailing global health disease with a high incidence rate which varies by region. It is a huge economic burden on health care providers. GI cancer affects different organs in the body such as the gastric organs, colon, esophagus, intestine, and pancreas. Internal and external factors like smoking, obesity, urbanization, genetic mutations, and prevalence of Helicobacter pylori and Hepatitis B and Hepatitis C viral infections could increase the risk of GI cancer. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in fruits, grains, and vegetables. Consumption of phytochemicals may protect against chronic diseases like cardiovascular disease, neurodegenerative disease, and cancer. Multiple studies have assessed the chemoprotective effect of selected phytochemicals in GI cancer, offering support to their potential towards reducing the pathogenesis of the disease. The aim of this review was to summarize the current knowledge addressing the anti-cancerous effects of selected dietary phytochemicals on GI cancer and their molecular activities on selected mechanisms, i.e., nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), detoxification enzymes, adenosine monophosphate activated protein kinase (AMPK), wingless-related integration site/β-catenin (wingless-related integration site (Wnt) β-catenin, cell apoptosis, phosphoinositide 3-kinases (PI3K)/ protein kinase B AKT/ mammalian target of rapamycin (mTOR), and mitogen-activated protein kinase (MAPK). In this review phytochemicals were classified into four main categories: (i) carotenoids, including lutein, lycopene, and β-carotene; (ii) proanthocyanidins, including quercetin and ellagic acid; (iii) organosulfur compounds, including allicin, allyl propyl disulphide, asparagusic acid, and sulforaphane; and (iv) other phytochemicals including pectin, curcumins, p-coumaric acid and ferulic acid. Overall, phytochemicals improve cancer prognosis through the downregulation of β-catenin phosphorylation, therefore enhancing apoptosis, and upregulation of the AMPK pathway, which supports cellular homeostasis. Nevertheless, more studies are needed to provide a better understanding of the mechanism of cancer treatment using phytochemicals and possible side effects associated with this approach.

T-2 toxin neurotoxicity: role of oxidative stress and mitochondrial dysfunction

Mycotoxins are highly diverse secondary metabolites produced in nature by a wide variety of fungi. Mycotoxins cause animal feed and food contamination, resulting in mycotoxicosis. T-2 toxin is one of the most common and toxic trichothecene mycotoxins. For the last decade, it has garnered considerable attention due to its potent neurotoxicity. Worryingly, T-2 toxin can cross the blood-brain barrier and accumulate in the central nervous system (CNS) to cause neurotoxicity. This review covers the current knowledge base on the molecular mechanisms of T-2 toxin-induced oxidative stress and mitochondrial dysfunction in the CNS. In vitro and animal data have shown that induction of reactive oxygen species (ROS) and oxidative stress plays a critical role during T-2 toxin-induced neurotoxicity. Mitochondrial dysfunction and cascade signaling pathways including p53, MAPK, Akt/mTOR, PKA/CREB and NF-κB contribute to T-2 toxin-induced neuronal cell death. T-2 toxin exposure can also result in perturbations of mitochondrial respiratory chain complex and mitochondrial biogenesis. T-2 toxin exposure decreases the mitochondria unfolded protein response and dampens mitochondrial energy metabolism. Antioxidants such as N-acetylcysteine (NAC), activation of Nrf2/HO-1 and autophagy have been shown to provide a protective effect against these detrimental effects. Clearly, translational research and the discovery of effective treatment strategies are urgently required against this common food-borne threat to human health and livestock.

Feed preference and feeding behaviours in grower broilers fed diets containing wheat naturally contaminated with fusarium mycotoxins

1. Two trials were conducted to determine the effect of feeding diets contaminated with fusarium mycotoxins (primarily deoxynivalenol (DON)) on broiler chicken feed preference, feeding behaviour and growth performance. 2. A total of 120 male Ross 308 chicks (4 birds/cage, 30 cages) were fed a common corn-based starter diet from 1 to 20 d of age. At 21 d, 15 cages were randomly assigned to the feed preference trial or a feeding behaviour trial. Three wheat-based experimental diets (0.14, 2.27 and 5.84 mg/kg DON) were prepared with a clean wheat and a naturally contaminated wheat. Broilers were ad libitum fed the experimental diets during 21-27 d. 3. In the preference trial, each cage's feeder was split into two equal-sized compartments so birds were provided a choice of two diets (control vs. low, control vs. high and low vs. high DON). In the feeding behaviour trial, diets were randomly assigned to 15 cages (5 cages/diet). Feeding and drinking behaviour was recorded for 1 h before and after the dark period and 1-h period at 9 h after the light was turned on (middle of day). Growth performance was assessed at 27 d. 4. In the preference trial, broilers preferred the control diet over low (93.0 vs. 66.1 g/d, P < 0.01) and high (104.4 vs. 50.4 g/d, P < 0.01) DON diets. At all three timepoints, where behaviour was recorded, birds offered the DON diets spent more time at the feeder compared to birds provided control diets (P < 0.05). Control birds had lower feed to gain ratio (1.65) than birds fed low (1.82) and high (1.94) DON diets (P < 0.01). 5. It is clear that broilers are sensitive to the presence of fusarium mycotoxins and that moderate levels of DON negatively affect feed preference and growth performance when fed during the grower period.

Anorectic responses to T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol correspond to plasma elevations of neurotransmitters 5-hydroxytryptamine and substance P

Trichothecene mycotoxins commonly contaminate cereal grains and are often linked to human and animal food poisoning. The rapid onset of anorexia is a common hallmark of trichothecenes-induced toxicity. Although the neurotransmitters 5-hydroxytryptamine (5-HT) and substance P (SP) are known to regulate appetite, it remains unknown whether these two neurotransmitters are involved in type A trichothecenes-induced anorectic response. The goal of this study is to relate plasma 5-HT and SP to anorectic responses induced by type A trichothecenes T-2 toxin (T-2), HT-2 toxin (HT-2), diacetoxyscirpenol (DAS) and neosolaniol (NEO). These four toxins evoked robust anorectic response and secretion of plasma 5-HT and SP at 1 mg/kg bw. Following oral exposure, plasma 5-HT and SP were elevated and all peaked at 2 h for T-2, HT-2, DAS and NEO. Following intraperitoneal (IP) administration, plasma 5-HT and SP were peaked at 6 h, 6 h, 2 h, 2 h and 2 h, 6 h, 2 h, 2 h for T-2, HT-2, DAS and NEO, respectively. Elevations of plasma 5-HT and SP markedly corresponded to anorexia induction by T-2, HT-2, DAS and NEO. Altogether, the results presented herein indicated that 5-HT and SP play contributory roles in anorectic responses induced by T-2, HT-2, DAS and NEO.

Potential roles for glucagon-like peptide-17-36 amide and cholecystokinin in anorectic response to the trichothecene mycotoxin T-2 toxin

Anorexia is a hallmark of animal and human exposed to T-2 toxin, a most poisonous trichothecene mycotoxins contaminating various cereal grains including wheat, corn and barley. Although this adverse effect has been well characterized in several animal species, the underlying mechanisms are unclear. The goal for this study was to elucidate the roles of two gut satiety hormones, glucagon-like peptide-1_7-36 amide (GLP-1) and cholecystokinin (CCK) in T-2 toxin-evoked anorectic response using a mouse anorexia bioassay. Elevations of plasma GLP-1 and CCK significantly corresponded to anorexia induction by T-2 toxin. Direct administration of exogenous GLP-1 and CCK markedly evoked anorectic responses similar to T-2 toxin. The GLP-1 receptor (GLP-1R) antagonist Exendin9-39 dose-dependently cause attenuation of both GLP-1- and T-2 toxin-induced anorectic responses. Pretreatment with the CCK1 receptor (CCK1R) antagonist SR 27897 and CCK2 receptor (CCK2R) antagonist L-365,260 attenuated anorexia induction by both CCK- and T-2 toxin in a dose dependent manner. Taken together, our findings suggest that both GLP-1 and CCK play contributory roles in T-2 toxin-induced anorexia.

Comparison of Anorectic Potencies of Type A Trichothecenes T-2 Toxin, HT-2 Toxin, Diacetoxyscirpenol, and Neosolaniol

Trichothecene mycotoxins are common contaminants in cereal grains and negatively impact human and animal health. Although anorexia is a common hallmark of type B trichothecenes-induced toxicity, less is known about the anorectic potencies of type A trichothecenes. The purpose of this study was to compare the anorectic potencies of four type A trichothecenes (T-2 toxin (T-2), HT-2 toxin (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO)) in mice. Following oral exposure to T-2, HT-2, DAS, and NEO, the no observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) were 0.01, 0.01, 0.1, and 0.01 mg/kg body weight (BW), and 0.1, 0.1, 0.5, and 0.1 mg/kg BW, respectively. Following intraperitoneal (IP) exposure to T-2, HT-2, DAS, and NEO, the NOAELs were 0.01 mg/kg BW, except for DAS (less than 0.01 mg/kg BW), and the LOAELs were 0.1, 0.1, 0.01, and 0.1 mg/kg BW, respectively. Taken together, the results suggest that (1) type A trichothecenes could dose-dependently elicit anorectic responses following both oral gavage and IP exposure in mice; (2) the anorectic responses follow an approximate rank order of T-2 = HT-2 = NEO > DAS for oral exposure, and DAS > T-2 = HT-2 = NEO for IP administration; (3) IP exposure to T-2, HT-2, DAS, and NEO evoked stronger anorectic effects than oral exposure. From a public health perspective, comparative anorectic potency data should be useful for establishing toxic equivalency factors for type A trichothecenes.

Anorectic response to the trichothecene T-2 toxin correspond to plasma elevations of the satiety hormone glucose-dependent insulinotropic polypeptide and peptide YY3-36

T-2 toxin, a potent type A trichothecene mycotoxin, is produced by various Fusarium species and can negatively impact animal and human health. Although anorexia induction is a common hallmark of T-2 toxin-induced toxicity, the underlying mechanisms for this adverse effect are not fully understood. The goal of this study was to determine the roles of two gut satiety hormones, glucose-dependent insulinotropic polypeptide (GIP) and Peptide YY_3-36 (PYY_3-36) in anorexia induction by T-2 toxin. Elevations of plasma GIP and PYY_3-36 markedly corresponded to anorexia induction following oral exposure to T-2 toxin using a nocturnal mouse anorexia model. Direct administration of exogenous GIP and PYY_3-36 similarly induced anorectic responses. Furthermore, the GIP receptor antagonist Pro3GIP dose-dependently attenuated both GIP- and T-2 toxin-induced anorectic responses. Pretreatment with NPY2 receptor antagonist JNJ-31020028 induced a dose-dependent attenuation of both PYY_3-36- and T-2 toxin-induced anorectic responses. To summarize, these findings suggest that both GIP and PYY_3-36 might be critical mediators of anorexia induction by T-2 toxin.

T-2 mycotoxin treatment of newborn rat pups does not significantly affect nervous system functions in adulthood

T-2 toxin is primarily produced by Fusarium sp. abundant under temperate climatic conditions. Its main harmful effect is the inhibition of protein synthesis. Causing oxidative stress, it also promotes lipid peroxidation and changes plasma membrane phospholipid composition; this may lead to nervous system alterations. The aim of the present study was to examine whether a single dose of T-2 toxin administered at newborn age has any long-lasting effects on nervous system functions. Rat pups were treated on the first postnatal day with a single intraperitoneal dose of T-2 toxin (0.2 mg/bwkg). Body weight of treated pups was lower during the second and third week of life, compared to littermates; later, weight gain was recovered. At young adulthood, behavior was tested in the open field, and no difference was observed between treated and control rats. Field potential recordings from somatosensory cortex and hippocampus slices did not reveal any significant difference in neuronal network functions. In case of neocortical field EPSP, the shape was slightly different in treated pups. Long-term synaptic plasticity was also comparable in both groups. Seizure susceptibility of the slices was not different, either. In conclusion, T-2 toxin did not significantly affect basic nervous system functions at this dose.

Glial Endozepines Inhibit Feeding-Related Autonomic Functions by Acting at the Brainstem Level

Endozepines are endogenous ligands for the benzodiazepine receptors and also target a still unidentified GPCR. The endozepine octadecaneuropeptide (ODN), an endoproteolytic processing product of the diazepam-binding inhibitor (DBI) was recently shown to be involved in food intake control as an anorexigenic factor through ODN-GPCR signaling and mobilization of the melanocortinergic signaling pathway. Within the hypothalamus, the DBI gene is mainly expressed by non-neuronal cells such as ependymocytes, tanycytes, and protoplasmic astrocytes, at levels depending on the nutritional status. Administration of ODN C-terminal octapeptide (OP) in the arcuate nucleus strongly reduces food intake. Up to now, the relevance of extrahypothalamic targets for endozepine signaling-mediated anorexia has been largely ignored. We focused our study on the dorsal vagal complex located in the caudal brainstem. This structure is strongly involved in the homeostatic control of food intake and comprises structural similarities with the hypothalamus. In particular, a circumventricular organ, the area postrema (AP) and a tanycyte-like cells forming barrier between the AP and the adjacent nucleus tractus solitarius (NTS) are present. We show here that DBI is highly expressed by ependymocytes lining the fourth ventricle, tanycytes-like cells, as well as by proteoplasmic astrocytes located in the vicinity of AP/NTS interface. ODN staining observed at the electron microscopic level reveals that ODN-expressing tanycyte-like cells and protoplasmic astrocytes are sometimes found in close apposition to neuronal elements such as dendritic profiles or axon terminals. Intracerebroventricular injection of ODN or OP in the fourth ventricle triggers c-Fos activation in the dorsal vagal complex and strongly reduces food intake. We also show that, similarly to leptin, ODN inhibits the swallowing reflex when microinjected into the swallowing pattern generator located in the NTS. In conclusion, we hypothesized that ODN expressing cells located at the AP/NTS interface could release ODN and modify excitability of NTS neurocircuitries involved in food intake control.

Appropriateness to set a group health based guidance value for T2 and HT2 toxin and its modified forms

The EFSA Panel on Contaminants in the Food Chain (CONTAM) established a tolerable daily intake (TDI) for T2 and HT2 of 0.02 μg/kg body weight (bw) per day based on a new in vivo subchronic toxicity study in rats that confirmed that immune‐ and haematotoxicity are the critical effects of T2 and using a reduction in total leucocyte count as the critical endpoint. An acute reference dose (ARfD) of 0.3 μg for T2 and HT2/kg bw was established based on acute emetic events in mink. Modified forms of T2 and HT2 identified are phase I metabolites mainly formed through hydrolytic cleavage of one or more of the three ester groups of T2. Less prominent hydroxylation reactions occur predominantly at the side chain. Phase II metabolism involves conjugation with glucose, modified glucose, sulfate, feruloyl and acetyl groups. The few data on occurrence of modified forms indicate that grain products are their main source. The CONTAM Panel found it appropriate to establish a group TDI and a group ARfD for T2 and HT2 and its modified forms. Potency factors relative to T2 for the modified forms were used to account for differences in acute and chronic toxic potencies. It was assumed that conjugates (phase II metabolites of T2, HT2 and their phase I metabolites), which are not toxic per se, would be cleaved releasing their aglycones. These metabolites were assigned the relative potency factors (RPFs) of their respective aglycones. The RPFs assigned to the modified forms were all either 1 or less than 1. The uncertainties associated with the present assessment are considered as high. Using the established group, ARfD and TDI would overestimate any risk of modified T2 and HT2.

Dysregulation of energy balance by trichothecene mycotoxins: Mechanisms and prospects

Trichothecenes are toxic metabolites produced by fungi that constitute a worldwide hazard for agricultural production and both animal and human health. More than 40 countries have introduced regulations or guidelines for food and feed contamination levels of the most prevalent trichothecene, deoxynivalenol (DON), on the basis of its ability to cause growth suppression. With the development of analytical tools, evaluation of food contamination and exposure revealed that a significant proportion of the human population is chronically exposed to DON doses exceeding the provisional maximum tolerable daily dose. Accordingly, a better understanding of trichothecene impact on health is needed. Upon exposure to low or moderate doses, DON and other trichothecenes induce anorexia, vomiting and reduced weight gain. Several recent studies have addressed the mechanisms by which trichothecenes induce these symptoms and revealed a multifaceted action targeting gut, liver and brain and causing dysregulation in neuroendocrine signaling, immune responses, growth hormone axis, and central neurocircuitries involved in energy homeostasis. Newly identified trichothecene toxicosis biomarkers are just beginning to be exploited and already open up new questions on the potential harmful effects of chronic exposure to DON at apparently asymptomatic very low levels. This review summarizes our current understanding of the effects of DON and other trichothecenes on food intake and weight growth.

Comparison of Anorectic Potencies of the Trichothecenes T-2 Toxin, HT-2 Toxin and Satratoxin G to the Ipecac Alkaloid Emetine

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Anorectic effects of natural toxins were compared in the mouse.

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Parenteral and oral T-2 and HT-2 toxin exposure caused prolonged anorexia.

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Emetine was more potent when delivered orally as compared to parenterally.

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Emetine's effects were less than T-2 and HT-2 toxin and more transient.

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Parental and intranasal delivery satratoxin G caused transient anorectic effects.

Trichothecene mycotoxins, potent translational inhibitors that are associated with human food poisonings and damp-building illnesses, are of considerable concern to animal and human health. Food refusal is a hallmark of exposure of experimental animals to deoxynivalenol (DON) and other Type B trichothecenes but less is known about the anorectic effects of foodborne Type A trichothecenes (e.g., T-2 toxin, HT-2 toxin), airborne Type D trichothecenes (e.g., satratoxin G [SG]) or functionally analogous metabolites that impair protein synthesis. Here, we utilized a well-described mouse model of food intake to compare the anorectic potencies of T-2 toxin, HT-2 toxin, and SG to that of emetine, a medicinal alkaloid derived from ipecac that inhibits translation. Intraperitoneal (IP) administration with T-2 toxin, HT-2 toxin, emetine and SG evoked anorectic responses that occurred within 0.5 h that lasted up to 96, 96, 3 and 96 h, respectively, with lowest observed adverse effect levels (LOAELs) being 0.1, 0.1, 2.5 and 0.25 mg/kg BW, respectively. When delivered via natural routes of exposure, T-2 toxin, HT-2 toxin, emetine (oral) and SG (intranasal) induced anorectic responses that lasted up to 48, 48, 3 and 6 h, respectively with LOAELs being 0.1, 0.1, 0.25, and 0.5 mg/kg BW, respectively. All four compounds were generally much more potent than DON which was previously observed to have LOAELs of 1 and 2.5 mg/kg BW after IP and oral dosing, respectively. Taken together, these anorectic potency data will be valuable in discerning the relative risks from trichothecenes and other translational inhibitors of natural origin.

Acute oral metformin enhances satiation and activates brainstem nesfatinergic neurons

OBJECTIVE

The study was designed to determine metformin effects on meal pattern, gastric emptying, energy expenditure, and to identify metformin-sensitive neurons and their phenotype.

METHODS

This study was performed on C57BL/6J and obese/diabetic (db/db) mice. Metformin (300 mg/kg) was administered by oral gavage. Food intake, meal pattern, oxygen consumption (VO2 ), and carbon dioxide production (VCO2 ) were obtained using an Oxylet Physiocage System. Gastric emptying assay and real-time RT-PCR from dorsal vagal complex extracts were also performed. C-Fos expression was used as a marker of neuronal activation. Phenotypic characterization of activated neurons was performed using either proopiomelanocortin (POMC)-Tau-Topaz GFP transgenic mice or NUCB2/nesfatin-1 and tyrosine hydroxylase (TH) labeling.

RESULTS

Acute per os metformin treatment slowed down gastric emptying, reduced meal size, but not meal number in a leptin-independent manner, and transiently decreased energy expenditure in a leptin-dependent manner. Metformin specifically activated central circuitry within the brainstem, independently of vagal afferents. Finally, while POMC neurons seemed sparsely activated, we report that a high proportion of the c-Fos positive cells were nesfatinergic neurons, some of which coexpressing TH.

CONCLUSIONS

Altogether, these results show that metformin modifies satiation by activating brainstem circuitry and suggest that NUCB2/nesfatin-1 could be involved in this metformin effect.

Diet, inflammation and the brain: commentary on the 2014 named series

This commentary will summarize the manuscripts in the 2014 Named Series, Diet, Inflammation, and the Brain. The series included studies that addressed the effect of dietary manipulations, including high fat diet, caloric restriction, or variations in dietary composition, on immune system endpoints in the brain, including microglial characterizations, changes in immune cell traffic into the brain, and markers of neuronal activation. Additionally, many of the studies assessed behavioral endpoints in parallel, including memory performance, social behavior and sickness behaviors (fever, decreased locomotion). Additionally, studies were included that focused on the converse relationship; the effect of immune system components (e.g., specific cytokines or chemokines) on metabolic and weight-related endpoints. The Named Series included both human and animal studies, as well as a review. Collectively, these studies highlight this growing area of research, which has great potential for identifying new ways to improve human health through diet.

Toxic phytochemicals and their potential risks for human cancer

Consuming plants for their presumed health benefits has occurred since early civilizations. Phytochemicals are found in various plants that are frequently included in the human diet and are generally thought to be safe for consumption because they are produced naturally. However, this is not always the case and in fact many natural compounds found in several commonly consumed plants are potential carcinogens or tumor promoters and should be avoided.