Michał Dąbrowski

The effect of low doses of zearalenone and its metabolites on progesterone and 17β-estradiol concentrations in peripheral blood and body weights of pre-pubertal female Beagle dogs.

The experiment involved 30 clinically healthy female Beagle dogs aged approximately 70 days with estimated initial body weight (BW) of 8 kg. The animals were randomly divided into two experimental groups (EI and EII) and a control group of 10 animals each. Group EI was intoxicated with 50 μg zearalenone/kg BW per os for 42 days, group EII received 75 μg zearalenone/kg BW per os for 42 days, and the control group was administered placebo per os for 42 days. The animals were weighed, and blood samples for analyses of the concentrations of zearalenone, its metabolites, progesterone and 17β-estradiol were collected seven times at seven-day intervals, one hour after mycotoxin administration. Biotransformation of zearalenone was observed in all groups throughout the experiment, and the highest percentage share of α-zearalenol was reported in group EII on the last five sampling dates (0.637-0.788 ng/ml, i.e. percentage share of 57.96-73.64%). The above had a significant influence on the non-physiological concentrations of progesterone and 17β-estradiol in both experimental (E) groups throughout the experiment. The lowest progesterone levels (0.131 ng/ml) were observed in group EII during the last test, and high concentrations of 17β-estradiol were found in group EII on the last two sampling dates (17.434 and 21.581 ng/ml, respectively) in comparison with control. Inhibited proliferation, manifested by a slower rate of body weight gain, was observed on the last but one day of zearalenone administration in both experimental groups. Our results indicate that NOAEL doses have stimulating/adaptive effects, whereas doses above NOAEL values suggest that even very low zearalenone doses can act as endocrine disruptors with regard to progesterone and 17β-estradiol.

Zearalenone in the Intestinal Tissues of Immature Gilts Exposed per os to Mycotoxins

Zearalenone and its metabolites, α-zearalenol and β-zearalenol, demonstrate estradiol-like activity and disrupt physiological functions in animals. This article evaluates the carryover of zearalenone and its selected metabolites from the digesta to intestinal walls (along the entire intestines) in pre-pubertal gilts exposed to low doses of zearalenone over long periods of time. The term “carryover” describes the transfer of mycotoxins from feed to edible tissues, and it was used to assess the risk of mycotoxin exposure for consumers. The experimental gilts with body weight of up to 25 kg were per os administered zearalenone at a daily dose of 40 μg/kg BW (Group E, n = 18) or placebo (Group C, n = 21) over a period of 42 days. In the first weeks of exposure, the highest values of the carryover factor were noted in the duodenum and the jejunum. In animals receiving pure zearalenone, the presence of metabolites was not determined in intestinal tissues. In the last three weeks of the experiment, very high values of the carryover factor were observed in the duodenum and the descending colon. The results of the study indicate that in animals exposed to subclinical doses of zearalenone, the carryover factor could be determined by the distribution and expression of estrogen receptor beta.

Changes in the Subpopulations of Porcine Peripheral Blood Lymphocytes Induced by Exposure to Low Doses of Zearalenone (ZEN) and Deoxynivalenol (DON).

Zearalenone and deoxynivalenol are secondary metabolites of fungi of the genus Fusarium. The presence of mycotoxins in cereals and the resulting contamination of feeds and foods pose health risks for animals and humans. The dangers associated with high doses of mycotoxins have been extensively researched but very little is known about NOAEL (No Observed Adverse Effect Level) doses or exposure to a combination of mycotoxins (mixed mycotoxicoses). The aim of this study was to determine the effects of six-week exposure to NOAEL doses of individual and combined mycotoxins on the subpopulations of CD4+8−, CD4−8+ and CD4+8+ lymphocytes in the peripheral blood of pigs. The experiment was performed on 72 gilts with average body weight of 25 kg, divided into three experimental groups (E1, E2 and E3, administered zearalenone (ZEN), deoxynivalenol (DON) and ZEN + DON, respectively, on a daily basis) and a control group (C) receiving placebo. Changes in lymphocyte subpopulations were evaluated by flow cytometry at weekly intervals (experimental days 7, 14, 21, 28, 35 and 42). A linear increase in the percentage of CD4+8+ lymphocytes was highly correlated with time (r = 0.682) in group C. The correlations and linear increase in the above subpopulation were disrupted in the remaining groups. In group E3, a statistically significant (p < 0.05) decrease in CD4+8+ counts was observed in week 5, which could point to a transient depletion of regulatory mechanisms of immune responses. The noted results also suggest that in mixed mycotoxicosis, ZEN and DON exerted stronger immunomodulatory effects.

Risk assessment for changes in the metabolic profile and body weights of pre-pubertal gilts during long-term monotonic exposure to low doses of zearalenone (ZEN).

The aim of the study was to examine whether the process of exposure to low doses of ZEN generates changes in the hematological and biochemical image of blood serum. During the experiment, pre-pubertal gilts (up to 25kg) were administered per os ZEN at a dose of 40μg/kg BW (Group E, n=18) or placebo (Group C, n=21) on a daily basis for 42days. Blood samples for investigation were collected seven times at intervals of one week. In the experimental groups, slight but statistically significant changes in the values of selected biochemical blood indices such as glucose, ALT, Pin, total protein and Fe, or in hematological indices such as RBC, MCV, PLT, WBC, basophils, eosinophils and monocytes were observed. Based on statistical analysis between the groups, differences in the values of WBC, basophils, peroxidase negative cells, Hb, Ht, MCV, HDW, glucose, ALT, AP, total protein, iron or potassium were found. In Group E, decreasing trends in the values of PLT and glucose, and increasing trends in the values of total protein, Pin, Na and Cl were found. The described situations occurred during the last three weeks of exposure. Low levels of exposure to ZEN lead to completely different changes in the metabolic profile than those resulting from higher doses of the toxin. The stimulatory effect of mycotoxins, observed in initial stages of exposure, is eliminated when the compensatory response and adaptive mechanisms are triggered, and due to excessive loss of energy, which may point to more efficient feed utilization and/or detoxification processes. The values of body weight gain obtained in Group E were monotonically higher in four out of the six investigated weeks of exposure. The above changes were accompanied by a decrease in glucose concentrations and higher total protein levels (a rising tendency), which could have affected the rate of body weight gain.

Evaluation of the proliferative activity of immunocompetent cells in the jejunal and iliac lymph nodes of prepubertal female wild boars diagnosed with mixed mycotoxicosis

Abstract The study evaluated the proliferative activity of immunocompetent cells in the jejunal and iliac lymph nodes of prepubertal female wild boars exposed to deoxynivalenol and zearalenone in naturally contaminated feed. The evaluation was performed with the use of the MTT assay and 2 mitogens: lipopolysaccharide (LPS) and concanavalin A. Intensified proliferative processes in T and B lymphocytes were revealed. The mitogenic activity of LPS was more expressed in the lymphocytes of both iliac and jejunal lymph nodes in comparison with the control group. Proliferative activity was higher in iliac lymph nodes than in jejunal lymph nodes. A reverse trend was observed in the percentage of live cells, which was higher in jejunal lymph nodes during the evaluation of lymphocyte proliferation.

Growth performance, selected blood biochemical parameters and body weights of pre-pubertal gilts fed diets supplemented with different doses of zearalenone (ZEN)

ABSTRACT The aim of this study was to determine whether exposure to low doses of zearalenone (ZEN) induces changes in the serum biochemical profile and body weights (BW). Pre‐pubertal gilts (with BW of up to 14.5 kg) were administered ZEN in daily doses of 5 &mgr;g/kg BW (group 1, n = 15), 10 &mgr;g/kg BW (group 2, n = 15), 15 &mgr;g/kg BW (group 3, n = 15) or placebo (control group C, n = 15) throughout the experiment. Blood was sampled for analysis on 10 dates (at five‐day intervals). Minor but statistically significant differences in the analysed serum biochemical parameters (ALT, AST, ALP, total cholesterol, total bilirubin, glucose, total protein, iron, BUN and urea) were observed in the studied groups. The biochemical parameters of the analysed gilts indicate that the maintenance of homeostasis and biotransformation of ZEN require considerable energy expenditure. Beginning on the fourth analytical date, BW gains were consistently higher in the experimental groups than in group C. The observed decrease in glucose and total protein levels can probably be attributed to higher BW gains and the ongoing ZEN biotransformation processes in the enterocytes and the liver. HighlightsExposure to low doses of ZEN induces a decrease in glucose and total protein levels, which contributes to weight gains.Low ZEN doses induce adaptive and/or compensatory mechanisms in pre‐pubertal gilts.Low doses of ZEN (MABEL, NOAEL and LOAEL) can exert a stimulatory effect on pre‐pubertal gilts.

The Genotoxicity of Caecal Water in Gilts Exposed to Low Doses of Zearalenone

Zearalenone is a toxic low-molecular-weight molecule that is naturally produced by moulds on crops as a secondary metabolite. The aim of this study was to determine the genotoxicity of caecal water collected successively from the caecal contents of gilts exposed to low doses (LOAEL, NOAEL, and MABEL) of zearalenone. The experiment was performed on 60 clinically healthy gilts with average BW of 14.5 ± 2 kg, divided into three experimental groups and a control group. Group ZEN5 were orally administered ZEN at 5 μg/kg BW, group ZEN10—10 μg ZEN/kg BW and group ZEN15—15 µg ZEN/kg BW. Five gilts from every group were euthanized on analytical dates 1, 2, and 3. Caecal water samples for in vitro analysis were collected from the ileocaecal region. The genotoxicity of caecal water was noted, particularly after date 1 in groups ZEN10 and ZEN15 with a decreasing trend. Electrophoresis revealed the presence of numerous comets without tails in groups C and ZEN5 and fewer comets with clearly expressed tails in groups ZEN10 and ZEN15. The distribution of LLC-PK1 cells ranged from 15% to 20% in groups C and ZEN5, and from 30% to 60% in groups ZEN10 and ZEN15. The analysis of caecal water genotoxicity during exposure to very low doses of ZEN revealed the presence of a counter response and a compensatory effect in gilts.

Effects of Streptozotocin-Induced Diabetes on the Pineal Gland in the Domestic Pig

Several observations from experiments in rodents and human patients suggest that diabetes affects pineal gland function, including melatonin secretion; however, the accumulated data are not consistent. The aim of the present study was to determine the effects of streptozotocin-induced diabetes on the pineal gland in the domestic pig, a species widely used as a model in various biomedical studies. The study was performed on 10 juvenile pigs, which were divided into two groups: control and diabetic. Diabetes was evoked by administration of streptozotocin (150 mg/kg of body weight). After six weeks, the animals were euthanized between 12.00 and 14.00, and the pineal glands were removed and divided into two equal parts, which were used for biochemical analyses and for preparation of explants for the superfusion culture. The pineal contents (per 100 μg protein) of serotonin, 5-hydroxyindole acetic acid, 5-hydroxytryptophol, 5-methoxyindole acetic acid, 5-methoxytryptophol, and 5-methoxytryptamine were significantly lower in diabetic pigs than in control pigs. In contrast, the level of N-acetylserotonin was significantly higher in diabetic animals. No significant differences were found in the level of melatonin between control and experimental pigs. The amounts of 3,4-dihydroxyphenylalanine, dopamine, norepinephrine, and 3,4-dihydroxyphenylacetic acid were significantly lower in the pineal glands of diabetic animals. The level of vanillylmandelic acid was higher in diabetic pigs. No differences were observed in the level of basal and NE-stimulated release of N-acetylserotonin or melatonin between the pineal explants prepared from control and experimental animals. In vitro treatment with insulin was ineffective. In conclusion, streptozotocin-induced diabetes affects both indole metabolism and adrenergic neurotransmission in the pig pineal gland.

The Effect of Deoxynivalenol on Selected Populations of Immunocompetent Cells in Porcine Blood—A Preliminary Study

Deoxynivalenol (DON) is one of the most prevalent mycotoxins in Europe. Pigs are an animal species that is most susceptible to this mycotoxin. Deoxynivalenol causes significant losses in pig production by lowering feed intake, decreasing daily weight gains, disrupting immune responses, and increasing susceptibility to diseases. The aim of this experiment was to determine the influence of feed contaminated with DON at concentrations insignificantly higher than recommended by the European Commission (900 µg/kg). The experimental feed contained 1008 μg DON/kg. The experiment was performed on eight weaners from the same litter. The animals were randomly divided into two groups: an experimental group (M, n = 4) fed contaminated feed and a control group (C, n = 4) administered feed free of mycotoxins. The experiment lasted for six weeks, and peripheral blood samples were collected from the animals for analyses of selected morphological parameters and changes in the percentages of CD4+8−, CD4−8+, and CD4+8+ lymphocytes and antigen-presenting cells (APC) with CD14+172+ (monocytes), CD172ahigh4−14− (conventional dendritic cells, cDC), and CD172adim4+14− (plasmacytoid dendritic cells, pDC) phenotypes. The morphological parameters of porcine blood samples were determined by flow cytometry with non-fluorescent particle-size calibration standards, and no differences were observed between groups M and C. An immunophenotyping analysis of lymphocytes and dendritic cells (DC) revealed an increase in the percentage of CD4+8−, CD172ahigh4−14−, and CD172adim4+14− cells, and a decrease in the number of CD4−8+ cells in group M. The results of this experiment suggest that prolonged exposure to low doses of DON can change the proportions of immunocompetent cells (a shift towards humoral immunity), without affecting their overall counts.