In vitro neuropharmacological evaluation of penitrem-induced tremorgenic syndromes: importance of the GABAergic system

Ethanol's interaction with BK channel α subunit residue K361 does not mediate behavioral responses to alcohol in mice

Large conductance potassium (BK) channels are among the most sensitive molecular targets of ethanol and genetic variations in the channel-forming α subunit have been nominally associated with alcohol use disorders. However, whether the action of ethanol at BK α influences the motivation to drink alcohol remains to be determined. To address this question, we first tested the effect of systemically administered BK channel modulators on voluntary alcohol consumption in C57BL/6J males. Penitrem A (blocker) exerted dose-dependent effects on moderate alcohol intake, while paxilline (blocker) and BMS-204352 (opener) were ineffective. Because pharmacological manipulations are inherently limited by non-specific effects, we then sought to investigate the behavioral relevance of ethanol's direct interaction with BK α by introducing in the mouse genome a point mutation known to render BK channels insensitive to ethanol while preserving their physiological function. The BK α K361N substitution prevented ethanol from reducing spike threshold in medial habenula neurons. However, it did not alter acute responses to ethanol in vivo, including ataxia, sedation, hypothermia, analgesia, and conditioned place preference. Furthermore, the mutation did not have reproducible effects on alcohol consumption in limited, continuous, or intermittent access home cage two-bottle choice paradigms conducted in both males and females. Notably, in contrast to previous observations made in mice missing BK channel auxiliary β subunits, the BK α K361N substitution had no significant impact on ethanol intake escalation induced by chronic intermittent alcohol vapor inhalation. It also did not affect the metabolic and locomotor consequences of chronic alcohol exposure. Altogether, these data suggest that the direct interaction of ethanol with BK α does not mediate the alcohol-related phenotypes examined here in mice.

Individual and combined effect of acrylamide, fumitremorgin C and penitrem A on human neuroblastoma SH-SY5Y cells

Acrylamide (AA) is a chemical compound that can be formed in certain foods during high-temperature cooking processes such as frying, baking, and roasting. Exposure to AA has been linked to several neurological effects, including peripheral neuropathy, ataxia, and impaired cognitive function. Penitrem A (PEN A) and Fumitremorgin C (FTC) are toxic mycotoxins produced by certain species of fungi, such as Penicillium Crustosum, Aspergillus Fumigatus and Neosartorya Fischeri. Both mycotoxins are commonly found in contaminated foods and animal feeds and have been linked to several adverse health effects in humans and animals, including the ability to disrupt normal functioning of the nervous system, tremors, seizures, muscle spasms, and convulsions. AA, PEN A, and FTC are all chemical contaminants. Understanding their toxicity and how they may affect human cells can help food safety authorities to establish safe exposure levels for these compounds through food and develop strategies to reduce their presence. The aim of this study was to explore the combined in vitro toxicological effects of AA, PEN A and FTC in SH-SY5Y cells. For this purpose, cells were treated with AA, FTC, and PEN A as an individual and combined treatment. The types of interactions were assessed by the isobologram analysis. The cell cycle was performed by flow cytometry. Additive effect in binary and tertiary combinations was the major effect according to isobologram graphics. Our results demonstrate that PEN A possessed the highest potential in disturbing cell cycle progression by disrupting cell density in G0/G1 phase.

The role of mycotoxins in neurodegenerative diseases: current state of the art and future perspectives of research

Mycotoxins are fungal metabolites that can cause various diseases in humans and animals. The adverse health effects of mycotoxins such as liver failure, immune deficiency, and cancer are well-described. However, growing evidence suggests an additional link between these fungal metabolites and neurodegenerative diseases. Despite the wealth of these initial reports, reliable conclusions are still constrained by limited access to human patients and availability of suitable cell or animal model systems. This review summarizes knowledge on mycotoxins associated with neurodegenerative diseases and the assumed underlying pathophysiological mechanisms. The limitations of the common in vivo and in vitro experiments to identify the role of mycotoxins in neurotoxicity and thereby in neurodegenerative diseases are elucidated and possible future perspectives to further evolve this research field are presented.

Mycotoxins Affecting Animals, Foods, Humans, and Plants: Types, Occurrence, Toxicities, Action Mechanisms, Prevention, and Detoxification Strategies-A Revisit

Mycotoxins are produced by fungi and are known to be toxic to humans and animals. Common mycotoxins include aflatoxins, ochratoxins, zearalenone, patulin, sterigmatocystin, citrinin, ergot alkaloids, deoxynivalenol, fumonisins, trichothecenes, Alternaria toxins, tremorgenic mycotoxins, fusarins, 3-nitropropionic acid, cyclochlorotine, sporidesmin, etc. These mycotoxins can pose several health risks to both animals and humans, including death. As several mycotoxins simultaneously occur in nature, especially in foods and feeds, the detoxification and/or total removal of mycotoxins remains challenging. Moreover, given that the volume of scientific literature regarding mycotoxins is steadily on the rise, there is need for continuous synthesis of the body of knowledge. To supplement existing information, knowledge of mycotoxins affecting animals, foods, humans, and plants, with more focus on types, toxicity, and prevention measures, including strategies employed in detoxification and removal, were revisited in this work. Our synthesis revealed that mycotoxin decontamination, control, and detoxification strategies cut across pre-and post-harvest preventive measures. In particular, pre-harvest measures can include good agricultural practices, fertilization/irrigation, crop rotation, using resistant varieties of crops, avoiding insect damage, early harvesting, maintaining adequate humidity, and removing debris from the preceding harvests. On the other hand, post-harvest measures can include processing, chemical, biological, and physical measures. Additionally, chemical-based methods and other emerging strategies for mycotoxin detoxification can involve the usage of chitosan, ozone, nanoparticles, and plant extracts.

Chemical Stimulation of Rodent and Human Cortical Synaptosomes: Implications in Neurodegeneration

Synaptic plasticity events, including long-term potentiation (LTP), are often regarded as correlates of brain functions of memory and cognition. One of the central players in these plasticity-related phenomena is the α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR). Increased levels of AMPARs on postsynaptic membranes thus constitute a biochemical measure of LTP. Isolated synaptic terminals (synaptosomes) are an excellent ex vivo tool to monitor synaptic physiology in healthy and diseased brains, particularly in human research. We herein describe three protocols for chemically-induced LTP (cLTP) in synaptosomes from both rodent and human brain tissues. Two of these chemical stimulation protocols are described for the first time in synaptosomes. A pharmacological block of synaptosomal actin dynamics confirmed the efficiency of the cLTP protocols. Furthermore, the study prototypically evaluated the deficiency of cLTP in cortical synaptosomes obtained from human cases of early-onset Alzheimer’s disease (EOAD) and frontotemporal lobar degeneration (FLTD), as well as an animal model that mimics FLTD.

In Vitro Toxicokinetics and Phase I Biotransformation of the Mycotoxin Penitrem A in Dogs

The tremorgenic mycotoxin penitrem A is produced by Penicillium species as a secondary metabolite on moldy food and feed. Dogs are sometimes exposed to penitrem A by consumption of spoiled food waste or fallen fruit. The lipophilic toxin crosses the blood-brain barrier and targets neuroreceptors and neurotransmitter release mechanisms in the central and peripheral nervous systems. Typical symptoms of penitrem A intoxication are periodical or continuous tremors, which can be passing, persistent or lethal, depending on the absorbed dose. There is presently no information on the biotransformation and toxicokinetics of penitrem A in dogs. The aim of the present study was therefore to identify potential metabolites of the toxin by performing in vitro biotransformation assays in dog liver microsomes. Analyses by liquid chromatography coupled to high-resolution mass spectrometry led to the provisional identification of eleven penitrem A phase I metabolites, which were tentatively characterized as various oxidation products. Furthermore, elimination parameters determined in in vitro assays run under linear kinetics were used for in vitro-to-in vivo extrapolation of the toxicokinetic data, predicting a maximal bioavailability of more than 50%. The metabolite profile detected in the in vitro assays was similar to that observed in the plasma of an intoxicated dog, confirming the predictive capability of the in vitro approach.

Identification of 'Voodoo': an emerging substance of abuse in Egypt

BACKGROUND

'Voodoo' is a new substance of abuse that recently spread among youth in Egypt. It has numerous potentially dangerous effects on humans. However, to date the composition of the main constituents of this compound is unknown.

PURPOSE

We sought to identify the active components of this unknown substance"voodoo".

METHODS

Three samples were collected and analysed by high-performance liquid chromatography with photodiode array detector (HPLC-PAD), gas chromatography/mass spectrometry (GC/MS), and ultra-performance liquid chromatography/mass spectrometry (UPLC-MS/MS) using targeted multiple reaction monitoring (MRM).

RESULTS

HPLC-PAD analysis showed that samples 1 and 2 had some common major peaks, the same retention time, and similar spectra, whereas sample 3 showed different peaks. GC/MS analysis revealed the presence of various putatively identified bioactive compounds, including quinazolines, morphinan alkaloid, cannabinoids, penitrem A, and the well-known synthetic cannabinoid FUB-AMB (methyl(2S)-2-{[1-[(4-fluorophenyl)methyl]indazole-3-carbonyl]amino}-3 methylbutanoate). UPLC-MS/MS analysis revealed the presence of common compounds such as tetrahydrocannabinol (THC), amphetamine, 3,4-methylenedioxyamphetamine, tramadol, and oxazepam.

CONCLUSION

We concluded that Voodoo is a mixture of substances of abuse at varying concentrations.

Tremorgenic and neurotoxic paspaline-derived indole-diterpenes: biosynthetic diversity, threats and applications

Indole-diterpenes (IDTs) such as the aflatrems, janthitrems, lolitrems, paspalitrems, penitrems, shearinines, sulpinines, and terpendoles are biogenetically related but structurally varied tremorgenic and neurotoxic mycotoxins produced by fungi. All these metabolites derive from the biosynthetic intermediate paspaline, a frequently occurring IDT on its own right. In this comprehensive review, we highlight the similarities and differences of the IDT biosynthetic pathways that lead to the generation of the main paspaline-derived IDT subgroups. We survey the taxonomic distribution and the regulation of IDT production in various fungi and compare the organization of the known IDT biosynthetic gene clusters. A detailed assessment of the highly diverse biological activities of these mycotoxins leads us to emphasize the significant losses that paspaline-derived IDTs cause in agriculture, and compels us to warn about the various hazards they represent towards human and livestock health. Conversely, we also describe the potential utility of these versatile molecules as lead compounds for pharmaceutical drug discovery, and examine the prospects for their industrial scale manufacture in genetically manipulated IDT producers or domesticated host microorganisms in synthetic biological production systems.

Putative neuromycotoxicoses in an adult male following ingestion of moldy walnuts

A tremorgenic syndrome occurs in dogs following ingestion of moldy walnuts, and Penicillium crustosum has been implicated as the offending fungus. This is the first report of suspected moldy walnut toxicosis in man. An adult male ingested approximately eight fungal-infected walnut kernels and after 12 h experienced tremors, generalized pain, incoordination, confusion, anxiety, and diaphoresis. Following symptomatic and supportive treatment at a local hospital, the man made an uneventful recovery. A batch of walnuts (approximately 20) was submitted for mycological culturing and identification as well as for mycotoxin analysis. Penicillium crustosum Thom was the most abundant fungus present on walnut samples, often occurring as monocultures on isolation plates. Identifications were confirmed with DNA sequences. The kernels and shells of the moldy walnuts as well as P. crustosum isolates plated on yeast extract sucrose (YES) and Czapek yeast autolysate (CYA) agars and incubated in the dark at 25 °C for 7 days were screened for tremorgenic mycotoxins and known P. crustosum metabolites using a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. A relatively low penitrem A concentration of only 1.9 ng/g was detected on the walnut kernels when compared to roquefortine C concentrations of 21.7 μg/g. A similar result was obtained from P. crustosum isolates cultured on YES and CYA, with penitrem A concentrations much lower (0.6-6.4 μg per g mycelium/agar) compared to roquefortine C concentrations (172-1225 μg/g). The authors surmised that besides penitrem A, roquefortine C might also play an additive or synergistic role in intoxication of man.

The fungal neurotoxin penitrem A induces the production of reactive oxygen species in human neutrophils at submicromolar concentrations

Penitrem A is a fungal neurotoxin that recurrently causes intoxication in animals, and occasionally also in humans. We have previously reported that penitrem A induced the production of reactive oxygen species (ROS) in rat cerebellar granule cells, opening for a new mechanism of action for the neurotoxin. The aim of this study was to examine the potential of penitrem A to induce ROS production in isolated human neutrophil granulocytes, and to study possible mechanisms involved. Penitrem A significantly increased the production of ROS in human neutrophils at concentrations as low as 0.25μM (40% increase over basal levels), as measured with the DCF fluorescence assay. The EC₅₀ determined for the production of ROS by penitrem A was 3.8μM. The maximal increase in ROS production was approximately 330% over basal levels at a concentration of 12.5μM. ROS formation was significantly inhibited by the antioxidant vitamin E (50μM), the intracellular Ca⁺² chelator BAPTA-AM (5μM), the mitogen activated protein kinase kinase (MEK) 1/2 and 5 inhibitor U0126 (1 and 10μM), the p38 mitogen activated protein kinase (MAPK) inhibitor SB203580 (1μM), the c-Jun amino-terminal kinase (JNK) inhibitor SP600125 (10μM), and the calcineurin inhibitors FK-506 and cyclosporine A (1.5 and 0.5μM, respectively). These finding suggest that penitrem A is able to induce an increase in ROS production in neutrophils via the activation of several MAPK-signalling pathways. We suggest that this increase may partly explain the pathophysiology generated by penitrem A neuromycotoxicosis in both humans and animals.

Astaxanthin and Docosahexaenoic Acid Reverse the Toxicity of the Maxi-K (BK) Channel Antagonist Mycotoxin Penitrem A

Penitrem A (PA) is a food mycotoxin produced by several terrestrial and few marine Penicillium species. PA is a potent tremorgen through selective antagonism of the calcium-dependent potassium BK (Maxi-K) channels. Discovery of natural products that can prevent the toxic effects of PA is important for food safety. Astaxanthin (AST) is a marine natural xanthophyll carotenoid with documented antioxidant activity. Unlike other common antioxidants, AST can cross blood brain barriers (BBBs), inducing neuroprotective effects. Docosahexaenoic acid (DHA) is polyunsaturated ω-3 fatty acid naturally occurring in fish and algae. DHA is essential for normal neurological and cellular development. This study evaluated the protective activity of AST and DHA against PA-induced toxicity, in vitro on Schwann cells CRL-2765 and in vivo in the worm Caenorhbitidis elegans and Sprague Dawley rat models. PA inhibited the viability of Schwann cells, with an IC₅₀ of 22.6 μM. Dose-dependent treatments with 10–100 μM DHA significantly reversed the PA toxicity at its IC₅₀ dose, and improved the survival of Schwann cells to 70.5%–98.8%. Similarly, dose-dependent treatments with 10–20 μM AST reversed the PA toxicity at its IC₅₀ dose and raised these cells’ survival to 61.7%–70.5%. BK channel inhibition in the nematode C. elegans is associated with abnormal reversal locomotion. DHA and AST counteracted the in vivo PA BK channel antagonistic activity in the C. elegans model. Rats fed a PA-contaminated diet showed high levels of glutamate (GLU), aspartate (ASP), and gamma amino butyric acid (GABA), with observed necrosis or absence of Purkinjie neurons, typical of PA-induced neurotoxicity. Dopamine (DA), serotonin (5-HT), and norepinephrine (NE) levels were abnormal, Nitric Oxide (NO) and Malondialdehyde (MDA) levels were significantly increased, and total antioxidant capacity (TAC) level in serum and brain homogenates was significantly decreased in PA-treated rats. DHA and AST treatments effectively counteracted the toxic effects of PA and normalized most biochemical parameters in rats. DHA and AST can be useful food additives to prevent and reverse PA food-induced toxicity.

Biotransformation of the fungal neurotoxin Thomitrem A by primary rat hepatocytes

The tremorgenic mycotoxin Thomitrem A is a secondary metabolite produced mainly by the fungus Penicillium crustosum that is frequently found on spoiled stored food and feed. Typical signs of intoxication observed in dogs after the consumption of food waste are emesis, tremors, seizures progressing to ataxia and lack of coordinated movements. How uptake of Thomitrem A relates to exposure is unknown so far since data on biotransformation and toxicokinetics are missing. In this study the toxin was therefore metabolised in an exploratory in vitro experiment by rat hepatocytes, and substrate depletion as well as the formation of hepatic metabolites were investigated. Seven metabolites were characterised by their retention times and fragmentation patterns in LC-MS/MS analysis. They were found to be products of oxidation and dehydration processes and occurred at different incubation time points, showing different signal abundance-time curve profiles. Toxicokinetic parameters were derived from the Thomitrem A depletion curve applying principles of in vitro-to-in vivo extrapolation (IVIVE). The predicted medium maximum bioavailability in rats could be of importance for the assessment of exposure in cases of intoxication if it was confirmed in vivo and in other species.

Indole-diterpenoid profiles of Claviceps paspali and Claviceps purpurea from high-resolution Fourier transform Orbitrap mass spectrometry

RATIONALE

The biological activities most commonly associated with indole-diterpenoids are tremorgenicity in mammals and toxicity in insects through modulation of ion channels. The neurotoxic effects of some analogues are the cause of syndromes such as 'ryegrass staggers' and 'Paspalum staggers' in cattle and sheep. Our purpose was to obtain and interpret mass spectra of some pure Claviceps-related indole-diterpenoids (paspaline, paspalinine, paxilline, paspalitrems A and B) to facilitate identification of related compounds for which standards were not available.

METHODS

C. paspali-infected Paspalum dilatatum as well as C. purpurea sclerotia obtained from infected Phalaris arundinacea were extracted and the extracts separated via liquid chromatography. Low- and high-resolution mass spectra were then obtained of known and potentially unknown indole-diterpenoids.

RESULTS

At least 20 different indole-diterpenoids were detected in the C. paspali extract with molecular masses ranging from 405 Da (C28H40NO) to 517 Da (C32H40NO5). The C. purpurea sclerotia were shown to contain several indole-diterpenoids with molecular masses ranging from 405 Da (C28H40NO) to 419 Da (C28H38NO2).

CONCLUSIONS

This study demonstrates for the first time that C. purpurea may also produce indole-diterpenoids. This might explain why grazing of Phalaris spp. is occasionally connected with a tremorgenic syndrome in cattle, called 'phalaris staggers'.

Penitrem A and analogues: toxicokinetics, toxicodynamics including mechanism of action and clinical significance

Penitrem A is a mycotoxin mainly produced by Penicillium crustosum, a fungal species occurring in all climate zones, ranging from tropical to arctic areas. P. crustosum produces a wide range of toxic metabolites, including penitrems, thomitrems and roquefortine C. The major metabolite, penitrem A, has been associated with several episodes of mycotoxicosis in dogs. The clinical symptoms of acute penitrem A intoxication include classical signs of neurotoxicity, such as tremors, convulsions, ataxia and nystagmus. The outcomes of penitrem A intoxication in animals range from total recovery to death, depending mainly on the level of exposure. Cases of suspected human mycotoxicosis following exposure to P. crustosum infected food, beer or inhalation of dust have also been reported. The toxicokinetics of penitrem A is scarcely studied. The toxin is rapidly absorbed, as demonstrated by the rapid onset of symptoms after exposure, but the absorption has not been quantified. Penitrem A is transported systemically after absorption and has been found in liver, kidney and brain as well as in serum and the gastrointestinal tract in exposed animals. Five phase I metabolites have been found in liver extracts of mice 60 min after oral exposure to penitrem A, while three metabolites were found after in vitro incubations with primary rat hepatocytes and rat liver microsomes. Only penitrem A was found in the brains of exposed mice or intoxicated dogs. The elimination has not been studied. Penitrem A is probably the main tremorgenic compound in Penicillium-infected food and feed commodities, since analogues had lower toxic potentials in comparative studies. Penitrem A affects the central as well as the peripheral nervous system. The toxin blocks the high-conductance Ca2+-activated potassium channels (BK) and impairs the GABAergic neurotransmission in the cerebellum. Animal poisoning by penitrem A is probably underdiagnosed due to a lack of knowledge among veterinarians.