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

Effective protective agents against the organ toxicity of T-2 toxin and corresponding detoxification mechanisms: A narrative review

T-2 toxin is one of the most widespread and toxic fungal toxins in food and feed. It can cause gastrointestinal toxicity, hepatotoxicity, immunotoxicity, reproductive toxicity, neurotoxicity, and nephrotoxicity in humans and animals. T-2 toxin is physicochemically stable and does not readily degrade during food and feed processing. Therefore, suppressing T-2 toxin-induced organ toxicity through antidotes is an urgent issue. Protective agents against the organ toxicity of T-2 toxin have been recorded widely in the literature, but these protective agents and their molecular mechanisms of detoxification have not been comprehensively summarized. In this review, we provide an overview of the various protective agents to T-2 toxin and the molecular mechanisms underlying the detoxification effects. Targeting appropriate targets to antagonize T-2 toxin toxicity is also an important option. This review will provide essential guidance and strategies for the better application and development of T-2 toxin antidotes specific for organ toxicity in the future.

A review of anorexia induced by T-2 toxin

The presence of anorexia in animals is the most well-known clinical symptom of T-2 toxin poisoning. T-2 toxin is the most characteristic type A toxin in the trichothecene mycotoxins. The consumption of T-2 toxin can cause anorexic response in mice, rats, rabbits, and other animals. In this review, the basic information of T-2 toxin, appetite regulation mechanism and the molecular mechanism of T-2 toxin-induced anorectic response in animals are presented and discussed. The objective of this overview is to describe the research progress of anorexia in animals produced by T-2 toxin. T-2 toxin mainly causes antifeedant reaction through four pathways: vagus nerve, gastrointestinal hormone, neurotransmitter and cytokine. This review aims to give an academic basis and useable reference for the prevention and treatment of clinical symptoms of anorexia in animals resulting from T-2 toxin.

Emesis to trichothecene deoxynivalenol and its congeners correspond to secretion of peptide YY and 5-HT

The type B trichothecenes pollute food crops and have been associated to alimentary toxicosis resulted in emetic reaction in human and animal. This group of mycotoxins consists deoxynivalenol (DON) and four structurally related congeners: 3-acetyl-deoxynivalenol (3-ADON), 15-acetyl deoxynivalenol (15-ADON), nivalenol (NIV) and 4-acetyl-nivalenol (fusarenon X, FX). While emesis induced by intraperitoneally dosed to DON in the mink has been related to plasma up-grading of 5-hydroxytryptamine (5-HT) and neurotransmitters peptide YY (PYY), the impact of oral dosing with DON or its four congeners on secretion of these chemical substances have not been established. The aim of this work was to contraste emetic influence to type B trichothecene mycotoxins by orally dosing and involve these influence to PYY and 5-HT. All five toxins attracted marked emetic reaction that are relevant to elevated PYY and 5-HT. The reduction in vomiting induced by the five toxins and PYY was due to blocking of the neuropeptide Y2 receptor. The inhibition of the induced vomiting response by 5-HT and all five toxins is regulated by the 5-HT3 receptor inhibitor granisetron. In a word, our results indicate that PYY and 5-HT take a key role in the emetic reaction evoked by type B trichothecenes.

Emetic Response to T-2 Toxin Correspond to Secretion of Glucagon-like Peptide-17–36 Amide and Glucose-Dependent Insulinotropic Polypeptide

The T-2 toxin, a major secondary metabolite of Fusarium Gramineae, is considered a great risk to humans and animals due to its toxicity, such as inducing emesis. The mechanism of emesis is a complex signal involving an imbalance of hormones and neurotransmitters, as well as activity of visceral afferent neurons. The T-2 toxin has been proven to induce emesis and possess the capacity to elevate expressions of intestinal hormones glucagon-like peptide-_17–36 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), both of which are important emetic factors. In addition, the activation of calcium-sensitive receptor (CaSR) and transient receptor potential (TRP) channels are engaged in intestinal hormone release. However, it is unknown whether hormones GLP-1 and GIP mediate T-2 toxin-induced emetic response through activating CaSR and TRP channels. To further assess the mechanism of T-2 toxin-induced emesis, we studied the hypothesis that T-2 toxin-caused emetic response and intestinal hormones GLP-1 and GIP released in mink are associated with activating calcium transduction. Following oral gavage and intraperitoneal injection T-2 toxin, emetic responses were observed in a dose-dependent manner, which notably corresponded to the secretion of GLP-1 and GIP, and were suppressed by pretreatment with respective antagonist Exending_9–39 and Pro3GIP. Additional research found that NPS-2143 (NPS) and ruthenium red (RR), respective antagonists of CaSR and TRP channels, dramatically inhibited both T-2 toxin-induced emesis response and the expression of plasma GLP-1 and GIP. According to these data, we observed that T-2 toxin-induced emetic response corresponds to secretion of GLP-1 and GIP via calcium transduction.

Glucose-Dependent Insulinotropic Polypeptide and Substance P Mediate Emetic Response Induction by Masked Trichothecene Deoxynivalenol-3-Glucoside through Ca2+ Signaling

Deoxynivalenol (DON), the most naturally-occurring trichothecenes, may affect animal and human health by causing vomiting as a hallmark of food poisoning. Deoxynivalenol-3-glucoside (D3G) usually co-occurs with DON as its glucosylated form and is another emerging food safety issue in recent years. However, the toxicity of D3G is not fully understood compared to DON, especially in emetic potency. The goals of this research were to (1) compare emetic effects to D3G by oral and intraperitoneal (IP) routes and relate emetic effects to brain-gut peptides glucose-dependent insulinotropic polypeptide (GIP) and substance P (SP) in mink; (2) determine the roles of calcium-sensing receptor (CaSR) and transient receptor potential (TRP) channel in D3G’s emetic effect. Both oral and IP exposure to D3G elicited marked emetic events. This emetic response corresponded to an elevation of GIP and SP. Blocking the GIP receptor (GIPR) diminished emetic response induction by GIP and D3G. The neurokinin 1 receptor (NK-1R) inhibitor Emend^® restrained the induction of emesis by SP and D3G. Importantly, CaSR antagonist NPS-2143 or TRP channel antagonist ruthenium red dose-dependently inhibited both D3G-induced emesis and brain-gut peptides GIP and SP release; cotreatment with both antagonists additively suppressed both emetic and brain-gut peptide responses to D3G. To summarize, our findings demonstrate that activation of CaSR and TRP channels contributes to D3G-induced emesis by mediating brain-gut peptide exocytosis in mink.

Toxic mechanisms of the trichothecenes T-2 toxin and deoxynivalenol on protein synthesis

The toxic mechanisms of trichothecenes, including T-2 toxin and deoxynivalenol (DON), are closely related with their effects on protein synthesis. Increasing lines of evidence show that T-2 toxin can reduce the levels of tight junction proteins, and nuclear factor erythroid 2-related factor 2 (Nrf2) by disrupting cellular barriers and the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) and Nrf2/heme oxygenase (HO)-1 pathways. Moreover, it can inhibit aggrecan synthesis, thus causing Kashin-Beck disease. Regarding type B trichothecene, DON inhibits activation marker and β-catenin synthesis by acting on immune cells and the wingless/integrated (Wnt) pathway; it also inhibits cell proliferation and immune surveillance. In addition, DON has been shown to destroy tight junctions, glucose transport, and tumor endothelial marker 8, thus disturbing intestinal function and changing cell migration. This review summarizes the inhibitory effects of the trichothecenes T-2 toxin and DON on different protein synthesis, while discussing their underlying mechanisms. Focus is given to the effects of these toxins on tight junctions, aggrecan, activation markers, and hormones including testosterone under the influence of steroidogenic enzymes. This review can extend the current understanding of the effects of trichothecenes on protein synthesis and help to further understand their toxic mechanisms.

The trichothecene neosolaniol stimulates an emetic response through neuropeptide Y2 and serotonin 3 receptors in mink

Type A trichothecene neosolaniol (NEO) is considered a potential risk to human and animal health by the European Food Safety Authority (EFSA). To date, available data do not allow making conclusions about the toxicological properties of this toxin. Trichothecenes have been previously demonstrated to induce emetic responses in mink, and this response has been associated with neurotransmitter peptide YY (PYY) and serotonin (5-hydroxytryptamine, 5-HT). The goal of this study was to compare emetic effects of NEO administered by intraperitoneal and oral routes and relate these effects to PYY and 5-HT. The effective doses resulting in emetic events in 50% of the animals following intraperitoneal and oral exposure to NEO were 0.4 and 0.09 mg/kg bw, respectively. This emetic response corresponded to elevated PYY and 5-HT levels. Blocking the neuropeptide Y2 receptor diminished emesis induction by PYY and NEO. The 5-HT3 receptor inhibitor granisetron completely restrained the induction of emesis by 5-HT and NEO. To summarize, our findings demonstrate that PYY and 5-HT play important roles in the NEO-induced emetic response.

The T2 Toxin Produced by Fusarium spp. Impacts Porcine Duodenal Nitric Oxide Synthase (nNOS)-Positive Nervous Structures-The Preliminary Study

T2 toxin synthetized by Fusarium spp. negatively affects various internal organs and systems, including the digestive tract and the immune, endocrine, and nervous systems. However, knowledge about the effects of T2 on the enteric nervous system (ENS) is still incomplete. Therefore, during the present experiment, the influence of T2 toxin with a dose of 12 µg/kg body weight (b.w.)/per day on the number of enteric nervous structures immunoreactive to neuronal isoform nitric oxide synthase (nNOS—used here as a marker of nitrergic neurons) in the porcine duodenum was studied using the double immunofluorescence method. Under physiological conditions, nNOS-positive neurons amounted to 38.28 ± 1.147%, 38.39 ± 1.244%, and 35.34 ± 1.151 of all enteric neurons in the myenteric (MP), outer submucous (OSP), and inner submucous (ISP) plexuses, respectively. After administration of T2 toxin, an increase in the number of these neurons was observed in all types of the enteric plexuses and nNOS-positive cells reached 46.20 ± 1.453% in the MP, 45.39 ± 0.488% in the OSP, and 44.07 ± 0.308% in the ISP. However, in the present study, the influence of T2 toxin on the intramucosal and intramuscular nNOS-positive nerves was not observed. The results obtained in the present study indicate that even low doses of T2 toxin are not neutral for living organisms because they may change the neurochemical characterization of the enteric neurons.

Selective stimulation of colonic L cells improves metabolic outcomes in mice

AIMS/HYPOTHESIS

Insulin-like peptide-5 (INSL5) is found only in distal colonic L cells, which co-express glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). GLP-1 is a well-known insulin secretagogue, and GLP-1 and PYY are anorexigenic, whereas INSL5 is considered orexigenic. We aimed to clarify the metabolic impact of selective stimulation of distal colonic L cells in mice.

METHODS

Insl5 promoter-driven expression of Gq-coupled Designer Receptor Exclusively Activated by Designer Drugs (DREADD) was employed to activate distal colonic L cells (LdistalDq). IPGTT and food intake were assessed with and without DREADD activation.

RESULTS

LdistalDq cell stimulation with clozapine N-oxide (CNO; 0.3 mg/kg i.p.) increased plasma GLP-1 and PYY (2.67- and 3.31-fold, respectively); INSL5 was not measurable in plasma but was co-secreted with GLP-1 and PYY in vitro. IPGTT (2 g/kg body weight) revealed significantly improved glucose tolerance following CNO injection. CNO-treated mice also exhibited reduced food intake and body weight after 24 h, and increased defecation, the latter being sensitive to 5-hydroxytryptamine (5-HT) receptor 3 inhibition. Pre-treatment with a GLP1 receptor-blocking antibody neutralised the CNO-dependent improvement in glucose tolerance but did not affect the reduction in food intake, and an independent group of animals pair-fed to the CNO-treatment group demonstrated attenuated weight loss. Pre-treatment with JNJ-31020028, a neuropeptide Y receptor type 2 antagonist, abolished the CNO-dependent effect on food intake. Assessment of whole body physiology in metabolic cages revealed LdistalDq cell stimulation increased energy expenditure and increased activity. Acute CNO-induced food intake and glucose homeostasis outcomes were maintained after 2 weeks on a high-fat diet.

CONCLUSIONS/INTERPRETATION

This proof-of-concept study demonstrates that selective distal colonic L cell stimulation has beneficial metabolic outcomes. Graphical abstract.

Type A Trichothecene Diacetoxyscirpenol-Induced Emesis Corresponds to Secretion of Peptide YY and Serotonin in Mink

The trichothecene mycotoxins contaminate cereal grains and have been related to alimentary toxicosis resulted in emetic response. This family of mycotoxins comprises type A to D groups of toxic sesquiterpene chemicals. Diacetoxyscirpenol (DAS), one of the most toxic type A trichothecenes, is considered to be a potential risk for human and animal health by the European Food Safety Authority. Other type A trichothecenes, T-2 toxin and HT-2 toxin, as well as type B trichothecene deoxynivalenol (DON), have been previously demonstrated to induce emetic response in the mink, and this response has been associated with the plasma elevation of neurotransmitters peptide YY (PYY) and serotonin (5-hydroxytryptamine, 5-HT). However, it is found that not all the type A and type B trichothecenes have the capacity to induce PYY and 5-HT. It is necessary to identify the roles of these two emetogenic mediators on DAS-induced emesis. The goal of this study was to determine the emetic effect of DAS and relate this effect to PYY and 5-HT, using a mink bioassay. Briefly, minks were fasted one day before experiment and given DAS by intraperitoneally and orally dosing on the experiment day. Then, emetic episodes were calculated and blood collection was employed for PYY and 5-HT test. DAS elicited robust emetic responses that corresponded to upraised PYY and 5-HT. Blocking the neuropeptide Y2 receptor (NPY2R) diminished emesis induction by PYY and DAS. The serotonin 3 receptor (5-HT3R) inhibitor granisetron totally restrained the induction of emesis by serotonin and DAS. In conclusion, our findings demonstrate that PYY and 5-HT have critical roles in DAS-induced emetic response.

Review article: Role of satiety hormones in anorexia induction by Trichothecene mycotoxins

The trichothecenes, produced by Fusarium, contaminate animal feed and human food in all stages of production and lead to a large spectrum of adverse effects for animal and human health. An hallmark of trichothecenes toxicity is the onset of emesis followed by anorexia and food intake reduction in different animal species (mink, mice and pig). The modulation of emesis and anorexia can result from a direct action of trichothecenes in the brain or from an indirect action in the gastrointestinal tract. The direct action of trichothecenes involved specific brain areas such as nucleate tractus solitarius in the brainstem and the arcuate nuclei in the hypothalamus. Activation of these areas in the brain leads to the activation of specific neuronal populations containing anorexigenic factors (POMC and CART). The indirect action of trichothecenes in the gastrointestinal tract involved, by enteroendocrine cells, the secretion of several gut hormones such as cholecystokinin (CCK) and peptide YY (PYY) but also glucagon-like peptide 1 (GLP-1), gastric inhibitory peptide (GIP) and 5-hydroxytryptamine (5-HT), which transmitted signals to the brain via the gut-brain axis. This review summarizes current knowledge on the effects of trichothecenes, especially deoxynivalenol, on emesis and anorexia and discusses the mechanisms underlying trichothecenes-induced food reduction.