The effect of deoxynivalenol on serotoninergic neurotransmitter levels in pig blood 1

Abstract

Deoxynivalenol (DON) produces two characteristic toxicological effects, decreased feed consumption (anorexia) and emesis. Both effects have been linked to increased central (CNS) serotoninergic activity. Although there has also been some indication of a peripheral involvement, the role of blood pools of serotonin and related compounds in mediating DON toxicity is not well defined. In this study, the effect of DON on plasma concentrations of serotonin (5‐hydroxytryptamine, 5HT), 5HIAA (5‐hydroxyindoleacetic acid) and tryptophan (TRP), as a reflection of an induced peripheral serotoninergic system, was investigated in swine.

Typical values for the plasma concentrations of 5HT, 5HIAA, and TRP were established in pigs. Following administration of DON, either intragastrically or intravenously, concentration changes in these substances were measured over an eight hour period. The effect of low and high toxin doses were also compared.

Analyses showed no effect on plasma levels of the compounds of interest, even at sufficient toxin doses to invoke emesis in the test animals. Any variation over the course of the study remained within acceptable control limits. These results indicated no peripheral effect by DON which could account for the increased serotoninergic activity associated with altered feeding behaviour or emesis.     

Effect of the appetite stimulant cyproheptadine on deoxynivalenol ‐ induced reductions in feed consumption and weight gain in the mouse 1

Abstract

Deoxynivalenol (DON, vomitoxin), a Fusarium mycotoxin, is suspected of inducing its anorectic/feed refusal activity through a serotoninergic (5HT) mechanism, possible via 5HT₂‐receptors. In this study the efficiency of cyproheptadine (CYP), a serotonin antagonist and known appetite stimulant, to attenuate the adverse effect of DON was investigated in mice. CYP was administered in the feed for two days before animals began receiving the DON, which was also added to the feed. Both agents were administered concurrently thereafter for a 12‐day period. Dosing levels included various combinations of the two compounds, ranging from 0–16 ppm DON and 0–20 ppm CYP.

Results showed that CYP could effectively offset the reduction in feed intake caused by dietary DON, but only when dose levels were optimized (CYP appeared to have a narrow effective dose range, which was also dependent on the DON concentration). In fact, optimum CYP doses were able to enhance feed intake in DON‐fed mice above control levels, indicating that more than just a direct block of the toxin's effect was occurring. Conversely though, the effect of CYP on weight gain (WG) was ambiguous. At the lower CYP doses (≤ 5 ppm), alone or in combination with the lowest DON level tested (4 ppm), a modest positive effect was noted, but at the higher DON concentrations (≥ 8 ppm) the overall WG generally remained depressed, and tended to be reduced further by increasing doses of CYP.

These results provide additional support that serotoninergic mechanisms probably play a role in mediating DON‐induced reduction in feed intake. Where and how DON actually initiates its anorectic effect, however, has not been resolved.     

Distribution of deoxynivalenol in cerebral spinal fluid following administration to swine and sheep 1

Abstract

Deoxynivalenol (DON) is one of the major mycotoxins produced by Fusarium fungi. In evaluating DON as a potent CNS (emetic, anorexic) agent, its cerebral spinal fluid (CSF) and plasma pharmacokinetics were studied in pigs, a species very sensitive to the effects of DON, and sheep, a more tolerant animal. After intravenous administration, DON was detected very rapidly (<2.5 min) in the CSF of both species, but whereas peak levels (t‐max) occurred at 5–10 min in sheep, in swine it was 30–60 min. It would appear that the very rapid and extensive tissue distribution of DON in swine (Vdγ = 1.13 1 kg^‐1) may be slowing the rate of diffusion of the toxin into the CSF compared to sheep (Vd_β = 0.19 1 kg^‐1) where the toxin is confined essentially to the extracellular compartment. Area under curve calculations indicate approximately 2 1/2 times the amount of toxin eventually reaches the pig CSF compared to sheep CSF.

A good relationship between blood‐CSF DON levels was apparent in both species, although limitations in detection methods made it impossible to resolve a slow terminal phase (γ) in swine CSF which was evident in the plasma profile after iv administration.

Following oral administration of DON to pigs, a close correlation between plasma and CSF DON levels was observed. The toxin could be detected in CSF for up to 20 hr post‐dosing.     

Investigation of the Ultraviolet Photolysis Method for the Determination of Organic Nitrogen in Aerosol Samples

Abstract

The research objective was to adapt the ultraviolet (UV)photolysis method to determine dissolved organic nitrogen (DON) in aqueous extracts of aerosol samples. DON was assumed to be the difference in total concentration of inorganic nitrogen forms before and after sample irradiation. Using a 2² factorial design the authors found that the optimal conversion of urea, amino acids (alanine, aspartic acid, glycine, and serine), and methylamine for a reactor temperature of 44 °C occurred at pH 2.0 with a 24-hr irradiance period at concentrations < µM of organic nitrogen. Different decomposition mechanisms were evident: the photolysis of amino acids and methylamine released mainly ammonium (NH₄ ⁺), but urea released a near equimolar ratio of NH₄ ⁺ and nitrate (NO₃ ^?). The method was applied to measure DON in the extracts of aerosol samples from Tampa, FL, over a 32-day sampling period. Average dissolved inorganic (DIN) and DON concentrations in the particulate matter fraction PM₁₀ were 78.1 ± 29.2 nmol-Nm^?3and 8.3 ± 4.9 nmol-Nm^?3, respectively. The ratio between DON and total dissolved nitrogen ([TDN] = DIN + DON) was 10.1 ± 5.7%, and the majority of the DON (79.1 ± 18.2%) was found in the fine particulate matter (PM_2.5) fraction. The average concentrations of DIN and DON in the PM_2.5 fraction were 54.4 ± 25.6 nmol-Nm^?3 and 6.5 ± 4.4 nmol-Nm^?3, respectively.     

Gamma aminobutyric acid radioreceptor‐assay a possible biomarker for human exposure to certain agrochemicals

Abstract

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the γ‐ aminobutyric acid (GABA)_A receptor‐ionophore sites. [³⁵S] tertiary‐butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABA_A receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centnfugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [³⁵S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the α‐endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8x10^‐11 gm of endosulfan in each ml of the blood samples.     

Effects of lindane on Daphnia magna during chronic exposure

Abstract

Acute and chronic toxicity tests with lindane were conducted on Daphnia magna. The 24‐hr static LC50 was 1.64 mgL^‐1. The sublethal effects of 0.16, 0.25, 0.32, 0.60 and 0.80 mgL^‐1 lindane on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 × 10⁵ cellsmL^‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were:mean total young per female, mean brood size, days to first brood, intrinsic rate of natural increase (r), growth, and survival. Reproduction as well as survival was significantly reduced at lindane concentrations of 0.25 mgL^‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of lindane. Growth, as measured by body length, was depressed significantly at 0.25 mgL^‐1 lindane and higher. The chronic data was used to formulate an acute/chronic ratio.     

Evaluation of a Daphnia magna renewal life‐cycle test method with diazinon

Abstract

Acute and chronic toxicity tests with diazinon (diethyl 2‐isopropyl‐6‐methyl‐4‐pyrimidinyl phosphorothionate) were conducted on Daphnia magna. The 24‐hr static LC50 was 0.86 μL.L^‐1. The sublethal effects of 0.05, 0.1, 0.5, 0.75 and 1.0 ngL^‐1 of diazinon concentrations on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 x 10⁵ cellsmL^‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were: mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction as well as survival was significantly reduced at diazinon concentrations of 0.10 ngL^‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of diazinon. Growth, as measured by body length, was depressed significantly at 0.05 ngL^‐1 of diazinon and higher concentrations. The maximum acceptable toxicant concentration (MATC) was calculated. The chronic data was used to formulate an acute/chronic ratio.     

Effects of cadmium,zinc, copper and manganese on hepatic parenchymal cell gluconeogenesis

Abstract

The effects of divalent cations on gluconeogenesis in enzy‐matically isolated rat hepatic parenchymal cells were examined. Cadmium, zinc and copper decreased glucose production from lactate (10 mM). However, manganese at 0.05 to 1.0 mM levels stimulated gluconeogenesis by the cells and reduced the effects of the Cd⁺², Zn⁺² and Cu⁺² on gluconeogenesis. The results indicate that under these in vitro conditions the cations altered an aspect of hepatic function—gluconeogenesis from lactate.     

Effect of the trichothecene deoxynivalenol on brain biogenic monoamines concentrations in rats and chickens

Male Sprague-Dawley rats (180 g) and 28-day-old Single Comb White Leghorn Cockerels (300 g) were orally dosed with deoxynivalenol (DON) at 2.5 mg kg-1 body weight. In the first experiment, whole brains were collected at 2, 6, 12, 24 and 48 hours after the toxin treatment and analyzed for brain biogenic monoamines by high-performance liquid chromatography with electrochemical detection. Although several interesting trends were observed, DON did not influence whole brain concentrations of monoamine neurotransmitters or their metabolites in either species, at any time. In a second experiment, brains were collected 24 hours postdosing, dissected into 5 brain regions (pons and medulla oblongata, cerebellum, hypothalamus, hippocampus and cerebral cortex), and analyzed. DON treatment resulted in significantly elevated concentrations of serotonin (HT) and 5-hydroxyindole-3-acetic acid (HIAA) in all brain regions of the rat. However, this was not seen in poultry, where DON treatment resulted in a decrease in norepinephrine (NE) in the hypothalamus and hippocampus, and a decrease in dopamine (DA) in the pons and medulla oblongata region. These results suggest that DON influences brain biogenic amine metabolism, and that there may be intraspecies differences in the central effects of this mycotoxin.     

The influence of deoxynivalenol and zearalenone on steroid hormone production by porcine ovarian granulosa cells in vitro

Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) are frequently occurring in feed of pigs together. The aim of this study was to evaluate the possible in vitro effects of DON and ZEA, alone or their combination on steroid secretion of porcine ovarian granulosa cells (GCs). A species-specific model with porcine ovarian GCs was used to study the potential endocrine disrupting effects of DON and ZEA alone and in co-exposure. Progesterone (P4) and estradiol (E2) were determined by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA). The results of this study demonstrate that DON alone at the higher concentrations may act to stimulate P4 (at 1,000, 2,000, 3,000 and 5,000 ng mL^?1 but not 10 and 100 ng mL^?1) and E2 (at 2,000, 3,000 and 5,000 ng mL^?1 but not 10, 100 and 1000 ng mL^?1) secretion. The effects of ZEA on P4 and E2 secretion were not confirmed. DON in combination with the other fusariotoxin ZEA may impair steroidogenesis. Results aslo demonstrate different toxicological effects of fusariotoxins on follicle stimulating hormone-induced secretion of P4 and E2. All these results taken together suggest that fusariotoxin and their interactions can impact ovarian steroidogenesis, thereby demonstrating their potential reproductive effects in pigs.     

Assessment of a potential preventive ability of amygdalin in mycotoxin-induced ovarian toxicity

The possible effects of a natural substance amygdalin and its combination with the mycotoxin deoxynivalenol (DON) on the steroid hormone secretion (progesterone and 17-β-estradiol) by porcine ovarian granulosa cells (GCs) were examined in this in vitro study. Ovarian GCs were incubated without (control group) and with amygdalin (1, 10, 100, 1,000 and 10,000 μg mL¹), or its combination with DON (1 μg mL¹) for 24 h. The release of steroid hormones was determined by ELISA. The progesterone secretion by porcine ovarian GCs was not affected by amygdalin in comparison to the control. However, the highest amygdalin dose (10,000 μg mL¹) caused a significant stimulation of the 17-β-estradiol release. A combination of amygdalin with DON significantly (P < 0.05) increased the progesterone release at all concentrations. Similarly, a stimulatory effect of amygdalin co-administered with DON was detected with respect to the 17-β-estradiol secretion at the highest dose (10,000 μg mL¹) of amygdalin and 1 μg mL¹ of DON. Noticeable differences between the effects of amygdalin alone and its combination with DON on the progesterone release were detected. In contrast, no differences between the stimulatory effects of amygdalin and its combination with DON on the 17-β-estradiol synthesis by porcine GCs were observed. Findings from this in vitro study did not confirm the expected protective effect of amygdalin on mycotoxin induced reprotoxicity. Our results indicate that the stimulatory effect of amygdalin combined with DON on the progesterone release was clearly caused by the DON addition, not by the presence amygdalin per se. On the other hand, the stimulation of 17-β-estradiol production was solely caused by the presence of amygdalin addition. These findings suggest a possible involvement of both natural substances into the processes of steroidogenesis and appear to be endocrine modulators of porcine ovaries.     

Aluminum interaction with human brain tau protein phosphorylation by various Kinases

Abstract

Phosphorylation is an indispensable process for energy and signal transduction in biological systems. AlCl₃ at 10 nM to 10 uM range activated in‐vitro [γ‐³²P)ATP phosphorylation of the brain (tau) T protein in both normal human or E.coli expressed T forms; in the presence of the kinases P34, PKP, and PKC. However, higher concentrations of ALCl₃ inhibited the T phosphorylation with P34, PKP, and PKC to a maximum at 1 mM level. AlCl₃ at 100 uM to 500 uM range induced non‐enzymatic phosphorylation of T with γ‐ATP, γ‐GTP, and α‐GTP. AlCl₃ activated histone phosphorylation by P34 in a similar pattern. The hyperphosphorylation of T by Al³⁺ was accompanied by molecular shift and mobility retardation in SDS‐PAGE. This may demonstrate the mechanism of the longterm neurological effect of Al³⁺ in human brain leading to the formation of the neurofibrillary tangles related to Alzeheimer's disease.     

Occurrence of mycotoxins in wheat grains exposed to fungicides on fusarium head blight control in southern Brazil

Mycotoxins occurrence in wheat grains impose risks to human and animal health. The southern Brazil has favorable weather conditions for Fusarium graminearum infections and consequently for mycotoxins accumulation on grains. The goal of this study was to evaluate the behavior of new wheat commercial genotypes to Fusarium Head Blight (FHB), to control performance of new fungicide formulations and their relationship with mycotoxins concentration in grains. The manly mycotoxin occurrence on wheat grains in southern Brazil was deoxynivalenol (DON). Two cultivars showed high DON concentration above the tolerance limits (>3000 μg kg^?1). Many other mycotoxins monitored presented concentrations below method detection limit. Satisfactory levels of fungicide effectiveness were achieved against F. graminearum. Some fungicides promoted a satisfactory decrease on DON accumulation in grains. The best results were obtained when prothioconazole was present. SDHI (Succinate dehydrogenase inhibitors) + QoI (Quinone outside inhibitors) fungicides showed benefic effects at FHB control at field, but it did not promote satisfactory reduction on DON contamination. Fungicides can be used satisfactory for FHB control and reduce DON contamination in grains in southern Brazil. The presence of prothioconazole should be recommended. Some genotypes showed high DON concentration and it was not directly related with FHB severity at field.     

Influence of additives in the end‐use mixes of tebufenozide on deposition,adhesion and persistence in spruce foliage

Abstract

A commercial flowable formulation of tebufenozide, RH‐5992 2F [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyl) hydrazine], was diluted with water, water and canola oil, and water and the methyl ester of canola oil, to provide six end‐use mixes with concentrations of 35 and 70 g of active ingredient (Al) litre^‐1. The mixes were applied at 70 and 140 g Al ha^‐1 over white spruce [Picea glauca (Moench) Voss] seedlings in a laboratory spray chamber and foliar concentrations of tebufenozide were determined over a 60‐d period. At intervals of time post‐spray, seedlings were sprayed with monosized droplets of Sunspray®11N as rainfall, and the amount of tebufenozide knocked off from foliage was determined. The potential energy of adhesion (PEA) of the Al particles on the foliage increased with time and varied according to the type of end‐use mix, its viscosity and the dosage sprayed.

The end‐use mixes were applied over white spruce trees under field conditions and persistence of tebufenozide was investigated. DT₅₀ values were influenced by the type of mix and dosage sprayed. Oil‐containing mixes and higher dosages increased the PEA of tebufenozide particles.     

The effects of relative humidity on the insecticidal properties of a diatomite‐based dust

Abstract

The feasibility of using diatomaceous earth (diatomite) as an insecticidal dust was investigated under conditions of high (80%) and low (10%) relative humidity, using the adult red flour beetle, Tribolium castaneum. Tested were diatomite and two lots of a commercial formulation of the same diatomite, containing 0.2% pyrethrins and 1.0% piperonyl butoxide. For comparison, talcum and a talcum‐based commercial formulation, containing the same concentrations of pyrethrins and piperonyl butoxide, were included in the tests. The insects were exposed to 0.08 mg/cm² of each material tested, equivalent to the label recommendation of 7 lb/acre for the diatomite‐based commercial insecticide. At 10% RH, higher doses of diatomite were also tested. Mortalities were determined at intervals for up to 84 hours.

Diatomite caused no mortalities at the experimental concentration, regardless of RH. At about four times that rate and 10% RH, it caused less than 5% mortality.

At 80% RH, the diatomite‐based product (P. C. P. Act #14074) was significantly more effective than the talcum‐based one (#13074). At 10% RH, however, the latter acted more quickly than the diatomite‐based formulations, but all produced nearly 100% mortality after 68 hours.

The results are discussed in terms of the physical characteristics of diatomite and in terms of the modes of insecticidal actions of diatomite and pyrethrins. It is concluded that diatomite alone, despite its attractiveness to environmental interests, is not likely to become an effective agent for controlling red flour beetles and other pest insects with similar water‐proofing mechanisms.     

Effects of the herbicide molinate on the metabolic activities of a degradative Streptomyces griseus strain

Abstract

Cometabolic degradation of the herbicide molinate was tested using two microorganisms, Arthrobacter sp., strain M3 and Streptomyces griseus strain M2; the latter classified on the basis of the presence of the enzymatic cofactor SF‐420. The strains M3 and M2, inoculated in a basic salts medium with glucose as carbon source and added with 100 mg L^‐1 of molinate, degraded respectively 35 and 51% of the herbicide in 36 days.

Increasing concentrations of molinate, ranging from 50 to 200 mg L^‐1 in glucose medium, did not affect the final ATP yield of the strain M2, but decreased the final growth yield and the ATP synthesis rate. Moreover, the onset of coenzyme SF‐420 synthesis was progressively delayed.

In contrast, surprisingly, SF‐420 final yield and production rate were increased by progressive increasing concentrations of molinate in the mineral medium.     

The role of tryptophan in don‐induced feed rejection

Abstract

Deoxynivalenol (DON, vomitoxin) commonly produced by Fusarium fungi can alter feeding behaviour of pigs and other farm animals. The effects of dietary tryptophan (TRP, precursor of brain amine serotonin) in combination with DON were examined in mice to determine if TRP can modulate DON toxicity. Results indicated that brain TRP can be influenced by dietary TRP, but no evidence of TRP potentiating DON toxicity was observed. Higher TRP levels likely induced amino acid imbalance leading to weight gain suppression.     

In vitro response of human ovarian cancer cells to dietary bioflavonoid isoquercitrin

Abstract

Isoquercitrin is a dietary bioflavonoid used as a food supplement. We studied the mechanism underlying its effect in human ovarian cancer cells using OVCAR-3 cell line. Viability, survival, apoptosis, release of human transforming growth factor-β1 (TGF-β1) and TGF-β1 receptor, and intracellular reactive oxygen species (ROS) generation by OVCAR-3 cells were examined after isoquercitrin treatment at concentrations 5, 10, 25, 50, and 100?μg mL^?1. AlamarBlue assay revealed that isoquercitrin did not cause any significant change (P?>?0.05) in cell viability as compared to control. Apoptotic assay using flow cytometry did not find any significant change (P?>?0.05) in the proportion of live, dead and apoptotic cells as compared to control. ELISA also showed that the release of human TGF-β1 and TGF-β1 receptor were not significantly (P?>?0.05) affected by isoquercitrin as compared to control. Chemiluminescence assay demonstrated that lower concentrations (5, 10, and 25?μg mL^?1) were able to exhibit beneficial effects by inhibiting the generation of intracellular ROS. In contrast, elevated concentrations of 50 and 100?μg mL^?1 led to oxidative stress (P?相似文献   

Characterization and application of the enzyme peroxidase to the degradation of the mycotoxin DON

Deoxynivalenol (DON), one of the main mycotoxins found in food matrices, has high level of toxicity. This study aimed to characterize the peroxidase enzyme extracted from rice bran to be applied to the biodegradation of DON in order to evaluate the potential peroxidase (PO) from rice bran (RB) has to degrade DON in optimal conditions. Purification and recovery factors of PO extracted from RB and purified by three-phase partitioning were 5.7% and 50%, respectively. PO had the highest level of activity in the phosphate buffer 5 mM pH 5.5 in both crude and purified forms, whose reaction temperatures were 25°C and 10°C. At the end of production, purification and characterization steps, specific activities of the bran were 115.79 U mg^?1 and 4363 U g^?1. Reduction in the mycotoxin DON in optimal conditions determined for PO from RB was 20.3%, a promising result when the aim is to adequate mycotoxicological levels to foods.     

Micronucleus frequency in sheep lymphocytes after in vitro exposure to fungicide tolylfluanid

The fungicide tolylfluanid (N - dichlorofluoromethylthio-N′, N - dimethyl - N - p - tolylsulfamide), was investigated by cytokinesis-block micronucleus assay. Tolylfluanid at the lowest concentration (1 × 10^{? 6}mol L^{? 1})did not influence significantly the frequency of micronuclei in sheep lymphocyte cultures in comparison with control (32.33 ± 3.51/1000 binucleated cells versus 30.33 ± 2.82/1000 binucleated cells in dimethylsulfoxide (DMSO) control, P = 0.44). Higher tolylfluanid concentrations (1 × 10^{? 4} and, 1 × 10^{? 5} mol L^{? 1}) resulted in a significant dose-dependent increase in the number of micronuclei in comparison with control (74.00 ± 13.00/1000 binucleated cells and 52.67 ± 10.12/1000 binucleated cells versus 30.33 ± 2. 82/1000 binucleated cells in DMSO control, P = 0.005 and 0.02, respectively, ANOVA followed by Tukey test P < 0.05). Many of the treated cells also possessed multiple micronuclei. Tolylfluanid did not affect the nuclear division index at all treatment concentrations. Our in vitro results thus demonstrate that tolylfluanid had a significant genotoxic effect at only the highest concentration tested.