The influence of experimental administration of low zearalenone doses on the expression of Th1 and Th2 cytokines and on selected subpopulations of lymphocytes in intestinal lymph nodes.

The aim of this study was to characterize the immune response taking place in ileocecal lymph nodes (ICLN) in control (n=15) and zearalenone (ZEN)-treated (n=15) pigs. The experiment was carried out over 42 days; a dose of 0.1 mg kg-1 feed day-1 of ZEN was administered to the animals. The dose used in the experiment was at a level where no adverse effects are observed (NOAEL) in the ovaries, uterus and vagina. ICLN samples for analysis were collected on the 14th, 28th and 42nd day of the experiment. The analysis of cytokine concentration in the tissues showed that pigs treated with ZEN had an increased level of cytokines produced by helper Th1 lymphocytes (IL-2, IL-12 and IFN-γ) on the 28th day of the experiment. The level of cytokines produced by helper Th2 lymphocytes (IL-4 and IL-10) was characterized by a statistically non-significant upward trend, as compared with the control group. Flow cytometry showed a linear decrease in the percentage of CD21+ B, CD2+ T and CD4+CD8- T cells and an increase in the percentage of CD8+CD4- and TCRγδ + T cells in pigs treated with ZEN. Both ZEN and α-ZEL (α-zearalenone) concentrations increased over time in the liver, but only ZEN concentration increased in ICLN. The results obtained demonstrate that a NOAEL concentration of ZEN shifts the immune response in pig ICLN towards Th1/Th17, probably with a simultaneous activation of M1 macrophages. Moreover, we observed an increase in humoral cytokine secretion; this can be explained by a negative feedback loop and a phenotypic switch of macrophages from M1 to M2, as well as a switch of immune response from Th1 to Th2 type. ZEN can therefore influence the process of cytokine secretion and the percentage of lymphocytes in ileocecal lymph nodes.

Zearalenone-induced changes in the lymphoid tissue and mucosal nerve fibers in the porcine ileum.

This is the first study to examine zearalenone-(ZEN) induced changes in the immune system of the ileum and substance P-(SP-) and vasoactive intestinal peptide-(VIP-) immunoreactive nerve fibers in the mucosa, which participate in the regulation of intestinal functions under physiological conditions and during pathological processes. The aim of this study was also to identify potential relationships between selected immune and neural elements in ileal Peyer's patches in pigs that were and were not exposed to ZEN. The experiment was performed on 10 prepubertal gilts divided into two groups: the experimental group (n=5) where ZEN was administered at 0.1 mg kg-1 feed day-1 for 42 days, and the control group (n=5) which was administered a placebo. The tissue levels of cytokines were determined by enzyme-linked immunosorbent assay which revealed elevated concentrations of IL-12/23 40p and IL-1 ß in animals exposed to ZEN. Flow cytometry revealed a lower percentage of CD21+ lymphocytes in pigs exposed to ZEN in comparison with control animals. The tissue levels of neuropeptides were evaluated in the dot blot procedure which demonstrated higher concentrations of VIP and SP in experimental pigs. In experimental animals, numerous VIP-like immunoreactive processes were observed, and SP-immunoreactive nerve fibers formed a very dense network. Our results demonstrate for the first time that ZEN can modify the chemical coding of nerve structures in the gastrointestinal system. Those modifications can be attributed to ZEN's impact on estrogen receptors or its pro-inflammatory properties, and they reflect changes that take place in the nervous system at the transcriptional, translational and metabolic level.

Zearalenone induces apoptosis and inhibits proliferation in porcine ileal Peyer's patch lymphocytes.

Zearalenone (ZEN) is one of the most active natural estrogenic compounds that induces apoptosis. This study has been prompted by the widespread occurrence of ZEN in food and feed and limited knowledge about the effects of exposure to low doses of ZEN on the immune system. The aim of the study was to verify the hypothesis that low doses of ZEN contribute to induction of apoptosis and inhibition of proliferation in lymphocytes of the germinal centers (GC) of ileal Peyer's patches (IPP) in pigs. The experiment was performed on 30 female Polish Large White pigs, aged 2 months, with body weight of 15-18 kg, divided into two groups: control (C, n = 15) and experimental (Z, n = 15). On days 14, 28 and 42 of exposure to ZEN (100 µg kg(-1) feed day(-1)), apoptosis in IPP GC was evaluated histologically in HE-stained specimens, immunohistochemically by active caspase-3 staining and in mononucleosome and oligonucleosome detection-based ELISA. Proliferation was evaluated histologically by mitosis detection in HE-stained specimens, immunohistochemically by PCNA staining and in the MTT tetrazolium salt colorimetric assay detecting mitogenic responses of B cells to LPS. Exposure to low doses of ZEN for several weeks intensified apoptosis and weakened proliferation in IPP lymphocytes. ZEN influences gut-associated lymphoid tissue (GALT) by decreasing the expression of CD21+ on B cells and by increasing the percentage of B1 cell populations.

Evaluation of selected serum biochemical and haematological parameters in gilts exposed per os to 100 ppb of zearalenone.

Zearalenone (ZEN) widely contaminates animal feed of plant origin. The recommended safe concentrations of ZEN in feeds for various animal species are set mainly based on the mycotoxin's hormonal properties (NOEL). Our growing knowledge about biologically active concentrations of ZEN, molecular mechanisms and cells/tissues targeted by ZEN indicates that the harmful effects exerted by this mycotoxin on animals may be far greater than previously believed. This experiment was performed on pre-pubertal gilts divided into a control group (n=9) and an experimental group (ZEN, n=9). The control group received placebo, whereas the experimental group was administered ZEN at a dose of 0.1 mg/kg feed (equivalent to 5 µg/kg BW/day) for 42 days. On days 14, 28 and 42 blood samples were collected from the animals to determine the concentrations of selected zearalenols, serum biochemical and haematological parameters. Conjugated ZEN was found in the blood serum of the experimental gilts. Changes in the analysed biochemical parameters included a transient increase in albumin and cholesterol levels. A statistically significant increase in the concentrations of neutrophilic and acidophilic granulocytes was observed in the white blood cell system. The results indicate that long-term per os exposure of pre-pubertal gilts to low doses of ZEN (below NOEL) has a modulatory effect on liver function and white blood cells.

Changes in Th1 and Th2 cytokine concentrations in ileal Peyer's patches in gilts exposed to zearalenone.

GALT induces tolerance to foreign food antigens and plays an important role in the development of food allergies and the inflammatory bowel disease. The immune function of GALT is significantly influenced by an equilibrium between Th1 and Th2 subpopulations and the cytokines they produce. Th1 cytokines participate in the induction of a cell-mediated immune response, whereas Th2 cytokines induce powerful antibody-mediated responses. Changes in Th1/Th2 cell polarization of an immune response are associated with susceptibility to autoimmune and infectious diseases. This experiment investigated changes in cytokine levels produced by Th1 and Th2 cells in ileal Payer's patches in gilts exposed to ZEN doses below the NOEL (approximately 8 microg kg(-1) BW) for 14, 28 and 42 days. A significant linear increase in IL-4 (40.32 +/- 1.55 ng mg(-1)--137.60 +/- 29.96 ng mg(-1)), and IL-10 (5.99 +/- 0.15 ng mg(-1)--16.39 +/- 1.11 ng mg(-1)) concentrations was observed. An increase in Th1 (IL-2 and IFN-gamma) cytokine levels was also noted in the experimental group, but it was not statistically significant. An HPLC analysis of Peyer's patches in group E animals revealed a linear increase in ZEN concentrations (3.65 +/- 0.91 ng g(-1)--4.72 +/- 1.85 ng g(-1)) and an absence of alpha-ZEL. IL-4 stimulates monocytes and macrophages, it induces the production of proinflammatory cytokines and it may directly and indirectly contribute to the development of inflammatory foci. Higher IL-4 levels could shift polarization toward Th2 cells, stimulate B cells to undergo class switching to produce IgE and contribute to the development of allergies.

The effect of in vivo exposure to zearalenone on cytokine secretion by Th1 and Th2 lymphocytes in porcine Peyer's patches after in vitro stimulation with LPS.

Most research studies investigating the estrogenic effects of zearalenone (ZEN) focus on the mycotoxin's effect on the reproductive system. Since estrogen receptors are present on various types of immunocompetent cells, ZEN can also modify diverse immune functions. This study analyzed immunocompetent cells isolated from Peyer's patches in the ileum of pigs administered ZEN in the estimated daily dose of 8 µg kg(-1) BW (equivalent of 100 µg kg(-1) feed per day(-1)). The objective of the study was to determine whether long-term exposure to low ZEN doses below the NOEL threshold leads to changes in the percentages of lymphocyte subpopulations and cytokine secretion by Th1 (IL-2, IFN-γ) and Th2 (IL-4 and IL-10) lymphocytes in Peyer's patches of the ileum after in vitro stimulation with lipopolysaccharides (LPS). Immunocompetent cells isolated from Payer's patches on experimental days 0, 14, 28 and 42 were cultured in vitro and stimulated with LPS. The presence of IL-2, IFN-γ, IL-4 and IL-10 in culture media was determined by the ELISA method. The results of the study indicate that ZEN inhibits IL-2 and IFN-γ secretion and stimulates IL-4 and IL-10 produc- tion by Th1 and Th2 lymphocytes by shifting the Th1/Th2 balance towards the humoral immune response. The above can promote allergic responses, as demonstrated by the increase in the size of B1 cell populations producing more autoantibodies. ZEN can also lower resistance to viruses and tumors by inhibiting the proliferation of NK cells and IFN-γ secretion.

The effect of T-2 toxin on percentages of CD4+, CD8+, CD4+ CD8+ and CD21+ lymphocytes, and mRNA expression levels of selected cytokines in porcine ileal Peyer's patches.

The immune system is one of the main toxicity targets of the T-2 toxin. In view of scant research data demonstrating the effect of T-2 on cellular and humoral responses in gut-associated lymphoid tissue (GALT), this study set out to investigate the effects of chronic exposure to low doses of the T-2 toxin (200 microg T-2 toxin kg(-1) feed) on percentages of CD4+ and CD8+ T lymphocytes, CD4+/CD8+ double-positive T lymphocytes, CD21+ B cells, and IL-2, IFN-gamma, IL-4 and IL-10 mRNA expression levels in porcine ileal Peyer's patches. The investigated material comprised ileum sections sampled from piglets (aged 8-10 weeks, body weight of 15-18 kg) on days 14, 28 and 42 of the experiment. After 42 days of exposure to T-2, a significant drop in the quantity of the IL-10 product was observed (R = 0.94; S.E. 0.49-0.79; p < 0.001). A gradual decrease in the amount of IL-4 and IFN-gamma cytokine transcripts was found throughout the experiment, but the reported trend was not significant. On experimental days 14 and 42, a significant increase in the percentage of CD8+ T lymphocytes was observed in comparison with the control (p = 0.04 and p = 0.05, respectively), whereas on day 28, a significant decrease in the percentage of the above subpopulation was noted (p = 0.00). The percentage of CD21+ B cells in the experimental group decreased steadily in comparison with the control, and the observed drop was significant on days 28 and 42 (p = 0.06 and p = 0.00, respectively). On days 14 and 28, the percentages of CD4+ and CD8+ T lymphocytes were lower in the experimental animals than in the control group, and the drop reported on day 28 was statistically significant (p = 0.03).

Zearalenone and deoxynivalenol mycotoxicosis in dairy cattle herds.

Mycotoxin contaminations pose a growing problem in animal production from the economic and toxicological point of view. Clinical symptoms of mycotoxicosis are relatively unspecific, making the disease difficult to diagnose. This study presents a clinical case of dairy cattle infected with natural mycotoxins produced by fungi of the genus Fusarium (zearalenone [ZEA] and deoxynivalenol [DON]) in eastern Poland. In dead and infected cows, the presence of ZEA and DON was determined in the blood serum, significant changes were observed in blood morphological and biochemical profiles, extravasations and bowel inflammations were also observed. The results reported testify to an acute autoimmune process in the intestines as well as immunosuppression.

The effect of experimental, long-term exposure to low-dose zearalenone mycotoxicosis on the histological condition of ovaries in sexually immature gilts.

Farm animals are at risk of exposure to zearalenone (ZEA) in feedstuffs, which may lead to aberrations in their reproductive development, thereby adversely affecting production outcomes. The objective of this study was to determine the effect of long-term (48 days), per os administration of low ZEA doses (50% [20 µg ZEA/kg body weight (bw)] and 100% [40 µg ZEA/kg bw] NOAEL values) on anatomopathological changes in the ovaries of sexually immature gilts. The experiment involved 12 clinically healthy gilts aged 2 months with an initial body weight of about 40 kg and a determined immune status. The animals were randomly divided into two experimental groups (E1, E2) and a control group (C; all n = 4). Group E1 received per os 20 µg ZEA/kg bw for 48 days; group E2 received per os 40 µg ZEA/kg bw for 48 days; and group C received per os placebo for 48 days. Analytical samples of the mycotoxin were administered daily per os in gelatine capsules before morning feeding. Animals were sacrificed at the end of the experiment. The results of anatomopathological examinations of the ovaries in immature gilts subjected to long-term, low-dose ZEA exposure showed that ZEA-induced experimental hyperoestrogenism lowered the proliferative ability of granulosa cells of the ovarian follicle walls and of the connective tissue of the ovarian stroma, in particular at the lower ZEA dose.

The biotransformation of chosen mycotoxins.

Despite the unfavourable influence of mycotoxins on human and animal health and few toxicological aspects that have been documented, about these biologically active substances has not been explored. Aiming at more knowledge and a better understanding of the effects and mechanism of mycotoxin action in mammals would provide the basics for developing strategies to restrain different mycotoxicoses. One of the processes not fully understood is biotransformation, to which mycotoxins are subjected the animal organism. Biotransformation is the conversion of mycotoxins to non-toxic metabolites and occurs mostly in the intestinal mucosal membrane and liver, although other tissues and systems also take part in this process. Mycotoxin biotransformation reactions can be considered bioinactivation or detoxication, but mycotoxin biotransformation processes could also result in products more toxic than the mycotoxin. It can be concluded from research studies that our knowledge of mycotoxin biotransformation is scarce.

Influence of low doses of deoxynivalenol on histopathology of selected organs of pigs.

Deoxynivalenol is one of mycotoxins that are most frequently determined in animal feed manufactured in Poland. The examination of histopathological lesions concomitant with deoxynivalenol intoxication is difficult because of the common, often synergistic, reaction of this mycotoxin with other toxins, such as zearalenone or ochratoxin A, which has a strong nephrotoxic activity. The possibility of estimating histopathological lesions in the course of intoxication with pure toxin at various doses is therefore of interest. Dosages used in this experiment relate to clinical cases observed in feeding the animals with whole ration feed obtained by processing feedingstuffs contaminated with Fusarium moulds. However, concerning the fact of one-shot administration of clinically pure toxin, the main question was if it was a sufficient dose to cause changes in the histopathological picture of gastrointestinal tract organs. The experiment was carried out on 12 nursery pigs of mixed breed (Polish White Large x Polish White Ear-pendent) with an average body weigh of 35 kg. The experimental nursery pigs were divided into 3 groups: group I (n=4)--control; group II (n=4)--DON administered at a dose of 0.2 mg/kg b.w.; group III (n=4)--DON administered at a dose of 0.4 mg/kg b.w. After slaughter of the animals, macroscopic examination was performed and segments of duodenum, jejunum, ileum, liver and mesenteric lymph nodes were sampled and assigned for histopathological examination. The results obtained equate to the clinically observed signs in swine production involving some nutrient metabolism disturbances in the gastrointestinal tract in the course of deoxynivalenol mycotoxicosis. Histopathological examination of segments of the duodenum, the jejunum, the ileum, the liver and the lymph nodes indicate that the regressive lesions are more expressed in the experimental group treated with the highest concentration of deoxynivalenol.

The evaluation of the efficacy of sodium carbonate as zearalenone destructor in feeding stuffs.

Contamination of feed with zearalenone (ZEA) is still a serious problem in farm animals feeding, especially in gilts, sensitive to this compound. The relative failure of current methods of decontamination and quality control lead us to look for new techniques. The commonly accepted method for breaking down ZEA was performed in controlled temperature and time conditions. Various sodium carbonate doses (0.5 - 4%) were added to feed naturally contaminated with ZEA (ZEA biosynthesis by F. graminearum isolates). These doses were found to be effective in in vitro studies. The addition of 2% sodium carbonate gave the best results in reducing the phytoestrogen in the feed.

Histological estimation of the small intestine wall after administration of feed containing deoxynivalenol, T-2 toxin and zearalenone in the pig.

Fusarium spp. moulds are common in moderate climate regions of North America, Asia and Europe. They produce hepatotoxic and nephrotoxic mycotoxins, acting like estrogens, impairing hemopoesis and immunosuppressing. Actively dividing skin cells, lymphatic tissue, haemopoetic tissue and gastrointestinal tissue are the most sensitive for these trichothecenes action. The mucosal membrane of the gastrointestinal tract is the first barrier of the organism contacting with foreign antigens like feed proteins, natural toxins, saprophytic and pathogenic microflora and mycotoxins. The aim of this study was to perform histological estimation of the porcine small intestine after short term intoxication with low doses of deoxynivalenol (DON), T-2 toxin (T-2) and zearalenone (ZEA) obtained from wheat naturally contaminated with Fusarium moulds. Experimental pigs (n=5) were fed for 14 days feed containing DON, T-2 and ZEA (28.9, 11.5 and 33.2 microg kg(-1) of feed). On the last day of the experiment, the animals were euthanised and samples of the jejunum were collected for histological examination. In the experimental pigs, normally developed intestinal villi and crypts were found. However, number of acidophilic granulocytes in the mucous membrane and decreased numbers of goblet cells, increased numbers of endothelial lymphocytes and numerous plasma cells in intestinal epithelium was observed. On the surface of the intestinal epithelium the glycocalyx was poorly developed. The results obtained suggest that short term intoxication with low doses of DON, T-2 and ZEA does not cause significant changes in the histological structure of the small intestine in the pig. However, low concentrations of DON, T-2 and ZEA probably influence enterocytes metabolism and evoke inflammation of the mucous membrane of the small intestine.

Ultrastructural changes of ovarian follicle and corpus luteum after experimental zearalenone mycotoxicosis in bitch.

The aim of the study was to determine the influence of experimental zearalenone (ZEA) mycotoxicosis on the ultrastructure of ovaries in bitches receving zearalenone for 100 days per os in the anestrus phase. Experiment has been conducted on 9 sexually mature clinically healthy bitches. The sexually mature animals aged 1-3 years were in anestrus. The dogs have been divided into three groups: EI and EII, receiving ZEAper os in two dosages (25 microg/kg and 50 microg/kg b.w.) and control animals which received placebo per os. On the last day of experiment, ovariohysterectomy was performed in all the bitches and the uterine samples were submitted to ultrastructural analyses. The study has revealed that long lasting administration of higher dose of zearalenone causes ultrastructural changes in the granular layer of ovarian follicles, which showed due to their biological activity decrease. The changes in the granular layer, atrophy of intercellular connections and the appearance of intercellular spaces can stand for reduced activity of this layer. Changes in morphology of mitochondria, rough endoplasmic reticulum and Golgi apparatus sugest ZEA influence on cell metabolism and secretory processes. It seems therefore that in bitches and other monogastric animals, intoxications induced by this mycotoxin causes ultrastructural changes in granular cells of ovarian follicles.

Histopathological examination of ovaries in bitches after experimental zearalenone mycotoxicosis.

The present study deals with the influence of experimental ZEA mycotoxicosis on histopathological lesions in ovaries of bitches, which were administered zearalenone per os during anestrus phase for one hundred days. The experiment was performed on 9 sexually mature, clinically healthy bitches. The animals assigned into two experimental groups received zearalenone per os at two doses, 25 microg/kg b.w. and 50 microg/kg b.w., respectively: the bitches from control group received placebo per os. On the last day of zearalenone intoxication, the bitches were ovariohystorectomized. Histopathology and immunohistochemistry were performed. The study revealed that zearalenone and its metabolites caused profound regressive lesions: granular cells degeneration and atrophy. Numerous edemas and blood extravasations were also found. The intensity of these changes was significantly dose dependent. Furthermore, in ovarian cells and tissues of both experimental groups, no reaction for PCNA antigen was observed. In conclusion, zearalenone and its metabolites exerts unfavorable effects on the morphology of ovaries in bitches.

Histopathological and immunohistochemical examinations, and changes in proliferation activity of the uterus in bitches following zearalenon micotoxicosis.

The research was aimed at determining the impact of the experimental oral administration of zearalenon on the uterus in bitches. The study was carried out on 9 sexually mature 1 to 3 year-old bitches that were divided into three groups: two experimental ones and a control group. The experimental animals were orally administered zearalenon at 25 microg/kg BW (body weight) (group DI; n=3) and 50 microg/kg BW (group DII; n=3) throughout 100 days while the control bitches (group K; n=3) were administered placebo. After the period of 100 days, ovariohysterectomy was performed, and the uterine samples were submitted to histopathological and immunohistochemical examinations in order to determine the structure of the wall and the presence of PCNA antigen. In the experimental animals, the histopathological examinations revealed regressive lesions, such as degeneration and atrophia within the endometrium and myometrium, and local circulatory disorders, i.e. edema and extravasation. These lesions were not reported in the controls. In the bitches administered zearalenon, the tissues did not express any proliferative activity as determined by the presence of PCNA. It is assumed that, following the administration of zearalenon for 100 days orally to bitches, disruption of the structures within the wall of the uterus (i.e. degeneration, atrophy, edema, and extravasation within the endometrium and myometrium) develops. This research proves that zearalenon ingested by bitches may lead to dysfunction of the uterus and cause disruption of its structures.

The impact of zearalenone on the level of the selected estrogens in blood serum of sexually immature gilts.

The aim of the study was to evaluate the influence of low dose (LOEL - lowest observed effect level) of zearalenone (200 microg/kg b.w.), applied per os for 7 days (short-term intoxication), on sexual behavior, concentration of the examined xenobiotic and its metabolite and selected estrogens in sexually immature gilts: ovariohysterectomised (group D1) and intact (group D2) animals. Clinical signs of oestrus (reddening, oedema and hyperaemia of the vulva and serorhoea from the reproductive tract--lack of standing reflex) were obserwed in group D1 on day 6 and in group D2 on day 4 of the experiment. Laboratory analyses of blood plasma were carried out determine the presence of zearalenone and alpha-zearalenole. They revealed an increase in the level of alpha-zearalenol before the oestrus, decrease in total amount of both examined substances on day when the oestrus appeared and increase in the level of both examined xenobiotics in the post oestrus period together with the higher share of zearalenone. Medium concentrations of estrone and estradiol within the borders of method determination in the majority of periods examined. Higher levels of estrone (32.0 pg/ml) were found on day 4, in the group D2 and estradiol (6.5 pg/ml) on day 6 in the D2 group. The presents study revealed that zearalenone applied per os at LOEL dose causes the incidence of apparent sexual readiness (without standing reflex) in sexually immature gilts with the somatically immature reproductive system.

Level of zearalenone in blood serum and lesions in ovarian follicles of sexually immature gilts in the course of zearalenone micotoxicosis.

The aim of the study was to determine how a low dose of zearalenone applied orally for eight days influences the level of zearalenone (ZEN) and alpha-zearalenole in blood plasma and causes the occurrence of histopathological changes in the cells of the ovarian follicles in sexually immature gilts. The animals were divided into 2 groups (control, C; n = 4 and experimental, E; n = 4). The gilts from group E were treated daily with zearalenone at a dose of 200 microg/kg b.w. The level of zearalenone and alpha-zearalenole (ZON as the sum of the levels of both zearalenone and alpha-zearalenole) was measured daily. On day eight of the experiment the animals were sacrificed and their ovaries were taken for histopathological examination. The tissue sections obtained were HE- and PAS-stained according to McManus. The presence of PCNA antigen was also estimated. The highest concentration of ZON was noted on day 5 in group E (8.16 +/- 2.49 ng/ml). External estrus symptoms without standing reflex were observed in group E on day 4. In group C there were no pathological changes in the ovaries. In group E, a few ovarian follicles were found, but they were located in the cortical layer. They were filled with a liquid substance rich in protein and without the granulosa layer. There was disintegration with apoptotic-like changes of the PCNA-negative cells in the granulosa layer of single mature follicles. On day 4 the dose of zearalenone caused disturbances in the process of development and maturation of some of the best developed ovarian follicles. This probably occurred through the activation of on apoptosis-like process of the granulosa cells with simultaneous manifestation of estrus without standing reflex.

Morphology and ultrastructure of small intestine mucosa in gilts with zearalenone mycotoxicosis.

Zearalenone (ZEA) is a mycotoxin produced by Fusarium. It evokes disruptions in sex cycle and changes in the morphology of the reproductive organs in pigs. The morphology and ultrastructure of the small intestine mucosa were assessed after the course of the experimental zearalenone mycotoxicosis. During the experiment, pigs were fed feed containing low doses of ZEA. The experiment lasted 7 days and it was carried out on sexually immature gilts that were divided into 3 groups: control group (C) and 2 experimental groups (E1, E2; n=8). Groups E1 and E2 were given ZEA every day at a dose of 200 and 400 microg/kg b.w. The samples of tissues were taken for examinations after the slaughter on the last day of the experiment. No significant changes in the morphology of the intestinal mucosa were found in the experimental animals. Increased activity of the goblet cells and high content of mucinogen vesicles, lymphocytic infiltration, increased activity of endocrine cells and the presence of Paneth cells on the bottom of intestinal crypts, which sugest mobilisation of the local defence mechanisms in the intestinal mucosa, were obseved in group E2.

Modification of zearalenone structure in model and natural conditions.

Zearalenone is a mycotoxin widely occurring in cereals and animal feed, and it is associated with hyperestrogenism and other reprodutive disorders in animals. A new method of detoxication of feedstuffs involves alkaline hydrolysis of toxic macrolactone (1) (as well as model compounds (2a, 2b)). The method caused modification of zearalenone structure under mild conditions and the toxin underwent irreversible hydrolysis with high efficiency.