Patricia Panther

Mycotoxin deoxynivalenol (DON) mediates biphasic cellular response in intestinal porcine epithelial cell lines IPEC-1 and IPEC-J2

The Fusarium derived mycotoxin deoxynivalenol (DON) is frequently found in cereals used for human and animal nutrition. We studied effects of DON in non-transformed, non-carcinoma, polarized epithelial cells of porcine small intestinal origin (IPEC-1 and IPEC-J2) in a low (200 ng/mL) and a high (2000 ng/mL) concentration. Application of high DON concentrations showed significant toxic effects as indicated by a reduction in cell number, in cellular reduction capacity measured by MTT assay, reduced uptake of neutral red (NR) and a decrease in cell proliferation. High dose toxicity was accompanied by disintegration of tight junction protein ZO-1 and increase of cell cycle phase G2/M. Activation of caspase 3 was found as an early event in the high DON concentration with an initial maximum after 6-8 h. In contrast, application of 200 ng/mL DON exhibited a response pattern distinct from the high dose DON toxicity. The cell cycle, ZO-1 expression and distribution as well as caspase 3 activation were not changed. BrdU incorporation was significantly increased after 72 h incubation with 200 ng/mL DON and NR uptake was only transiently reduced after 24 h. Low dose effects of DON on intestinal epithelial cells were triggered by mechanisms different from those responsible for the high dose toxicity.

The Fusarium toxin deoxynivalenol (DON) modulates the LPS induced acute phase reaction in pigs

The systemic effects of the Fusarium toxin deoxynivalenol (DON) and of bacterial lipopolysaccharides (LPS) were studied in male castrated pigs (40.4 ± 3.7 kg) infused intravenously with either DON or LPS alone (100 μg DON/kg/h, 7.5 μg/LPS/kg/h), or together (100 μg DON plus 7.5 μg/LPS/kg/h). The Control group received a saline infusion (n=6/treatment, 24h observation period). An additional DON infusion did not exacerbate the clinical signs observed in LPS-infused pigs. For example, rectal temperature climaxed after 4h (40.4 ± 0.2°C) and 5h (40.1 ± 0.3°C), in the LPS and LPS+DON group, respectively. Saline and DON alone did not induce an acute phase reaction as indicated by unaltered plasma levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) while LPS caused a significant rise of both cytokines. TNF-alpha plasma peak concentrations were significantly higher in the LPS compared to the DON+LPS group (94.3 ± 17.2 ng/mL vs. 79.2 ± 15.7 ng/mL) while IL-6 climaxed earlier in the latter group (3h p.i. vs. 2h p.i.). From the tested clinical-chemical plasma characteristics the total bilirubin concentration and the ASAT activity were strongly elevated by the LPS infusion and additionally increased and decreased by DON, respectively. In conclusion, the LPS-induced effects were only marginally modified by DON.

A chronic oral exposure of pigs with deoxynivalenol partially prevents the acute effects of lipopolysaccharides on hepatic histopathology and blood clinical chemistry

Lipopolysaccharides (LPS), a cell wall component of gram-negative bacteria, and deoxynivalenol (DON), a prevalent Fusarium-derived contaminant of cereal grains, are each reported to have detrimental effects on the liver. A potentiating toxic effect of the combined exposure was reported previously in a mouse model and hepatocytes in vitro, but not in swine as the most DON-susceptible species. Thus, pigs were fed either a control diet (CON) or a Fusarium contaminated diet (DON, 3.1mg DON/kg diet) for 37 days. At day 37 control pigs were infused for 1h either with physiological saline (CON_CON), 100μg/kg BW DON (CON_DON), 7.5μg/kg BW LPS (CON_LPS), or both toxins (CON_DON/LPS) and Fusarium-pigs with saline (DON_CON) or 7.5μg/kg BW LPS (DON_LPS). Blood samples were taken before and after infusion (-30, +30, +60, +120, and +180min) for clinical blood chemistry. Pigs were sacrificed at +195min and liver histopathology was performed. LPS resulted in higher relative liver weight (p<0.05), portal, periportal and acinar inflammation (p<0.05), haemorrhage (p<0.01) and pathological bilirubin levels (CON_CON 1.0μmol/L vs. CON_LPS 5.4μmol/L, CON_DON/LPS 8.3μmol/L; p<0.001). DON feeding alleviated effects of LPS infusion on histopathology and blood chemistry to control levels, whereas DON infusion alone had no impact.

Interactions between the Fusarium toxin deoxynivalenol and lipopolysaccharides on the in vivo protein synthesis of acute phase proteins, cytokines and metabolic activity of peripheral blood mononuclear cells in pigs

The in vivo effects of the Fusarium toxin deoxynivalenol (DON) on albumin and fibrinogen synthesis in pigs and metabolic activity of porcine peripheral blood mononuclear cells (PBMCs) were studied alone or in combination with lipopolysaccharides (LPSs) in order to examine proposed synergistic effects of both substances. A total of 36 male castrated pigs (initial weight of 26 kg) were used. Uncontaminated (Control) and naturally DON-contaminated (chronic oral DON, 3.1mg/kg diet) wheat was fed for 37 days. On the day of protein synthesis measurement, pigs recruited from the Control group were treated once intravenously with (iv) DON (100 μg/kg live weight (LW)/h), iv LPS (7.5 μg/kgLW/h) or a combination of both substances, and six pigs from the chronic oral group were treated once with iv LPS. A treatment with DON alone exhibited no alterations of acute phase protein synthesis and metabolic activity of PBMC. There was no evidence that the chosen dosing regimen of DON had influences on the induced sub-acute stage of sepsis, as the LPS challenge, irrespective of DON co-exposure, mediated an acute phase reaction with a typical decrease of albumin synthesis, as well as changes in cytokine concentration and a loss of metabolic activity in PBMC.

The plasma clearance of the Fusarium toxin deoxynivalenol (DON) is decreased in endotoxemic pigs

The plasma elimination kinetics of the Fusarium toxin deoxynivalenol (DON) was investigated in male castrated pigs (40.4±3.7 kg) when infused intravenously either alone (100 μg/kg/h, n=6) or together with lipopolysaccharides (LPS, 7.5 μg/kg/h, n=6). The maximum DON concentration after one hour of infusion was significantly higher by 61% in the DON+LPS Group compared to pigs infused with DON alone. The area under the plasma DON concentration vs. time curve of the DON+LPS Group was approximately twice as high as that of the DON Group after 24h while the initial (0.63 vs. 0.6 h) and terminal half-lifes (2.97 vs. 2.30 h) remained uninfluenced. The apparent volume of distribution and the plasma clearance were significantly lower for the DON+LPS Group compared to the DON Group (2.14 vs. 1.45 L/kg and 11.9 vs. 5.87 mL/kg/min). Glucuronidated DON seemed to persist longer in the DON+LPS Group. In conclusion, clearance of DON was decreased during an LPS induced acute phase reaction in pigs. Whether the higher plasma DON concentrations in endotoxemic pigs are due to a hemodynamically associated longer persistence of the DON glucuronide or because of an altered glucuronidation activity needs to be examined further.

Interactions of deoxynivalenol and lipopolysaccharides on tissue protein synthesis in pigs

Possible interactions between the Fusarium toxin deoxynivalenol and lipopolysaccharides on in vivo protein synthesis were investigated in selected porcine tissues. A total of 36 male castrated pigs (initial weight of 26 kg) were used. 24 pigs were fed a control diet and 12 a Fusarium-contaminated diet (chronic oral deoxynivalenol, 3.1 mg/kg diet) for 37 days. Tissue protein synthesis was measured in pigs fed control diet after intravenous infusion of deoxynivalenol (100 µg/kg live weight/h), lipopolysaccharides (7.5 µg/kg live weight/h) or a combination of both compounds on the day of the measurements, while six pigs from the chronic oral deoxynivalenol group were intravenously treated with lipopolysaccharides (7.5 µg/kg live weight/h). Deoxynivalenol challenge alone failed to alter protein synthesis parameters. Fractional protein synthesis rates were exclusively reduced in liver, spleen and small intestine of lipopolysaccharides-treated pigs. Intravenous deoxynivalenol co-exposure enhanced the impacts of...

Deep Brain Stimulation of the Pedunculopontine Tegmental Nucleus (PPN) Influences Visual Contrast Sensitivity in Human Observers.

The parapontine nucleus of the thalamus (PPN) is a neuromodulatory midbrain structure with widespread connectivity to cortical and subcortical motor structures, as well as the spinal cord. The PPN also projects to the thalamus, including visual relay nuclei like the LGN and the pulvinar. Moreover, there is intense connectivity with sensory structures of the tegmentum in particular with the superior colliculus (SC). Given the existence and abundance of projections to visual sensory structures, it is likely that activity in the PPN has some modulatory influence on visual sensory selection. Here we address this possibility by measuring the visual discrimination performance (luminance contrast thresholds) in a group of patients with Parkinson’s Disease (PD) treated with deep-brain stimulation (DBS) of the PPN to control gait and postural motor deficits. In each patient we measured the luminance-contrast threshold of being able to discriminate an orientation-target (Gabor-grating) as a function of stimulation frequency (high 60Hz, low 8/10, no stimulation). Thresholds were determined using a standard staircase-protocol that is based on parameter estimation by sequential testing (PEST). We observed that under low frequency stimulation thresholds increased relative to no and high frequency stimulation in five out of six patients, suggesting that DBS of the PPN has a frequency-dependent impact on visual selection processes at a rather elementary perceptual level.