Effet chez le porcelet d'une exposition à un régime co-contaminé en ...

INTRODUCTIONdue to the ingestion of co-contaminated feed is in accordance with the histopathologicalobservations (see below).Another parameter correlated with hepatotoxicity, is the relative weight of liver. Interestingly,either an increase or a decrease of the RW-L was observed in the experiments for the combinedtreatment (Table 1). This is attributed to the individual effect of each toxin, showing either anincrease or a decrease for this parameter, according to studies. A synergistic interaction type 2 or 3was recorded in pigs, turkeys, and rats exposed to both toxins (Harvey et al., 1995b; Kubena et al.,1995b; Pozzi et al., 2001). It would be possible that the mixture induced enough hepatic cell walldamage to have a major effect on total hepatic parenchymal mass. By contrast, other studies havereported an increase in the RW-L, but leading to a less than additive (Dilkin et al., 2003; Tessari et al.,2006) or an antagonistic interaction (Tessari et al., 2006; Weibking et al., 1994) in animals receivingmulti-contaminated feed.In two studies, ALP concentration was decreased when animals were fed with AF (Casado et al.,2001; Kubena et al., 1995b). The authors suggested that it was due to the inhibition of proteinsynthesis by AF. The combination of AF with FB led to a lesser reduction, suggesting an antagonisticinteraction (Table 1).c) effects of AF and FB on lipidsDisruption of sphingolipid biosynthesis is the main mechanism involved in FB toxicity, withinhibition of ceramide synthase leading to accumulation of sphingoid bases (sphinganine, Sa andsphingosine, So). This inhibition is well documented and the Sa/So ratio is considered as a goodindicator of FB exposure (Theumer et al., 2008).Three studies analyzed the effect of co-exposure to AF and FB on sphingoid bases in differentbiological samples, with the aim of investigating if AF could exacerbate the toxicity of FB (Orsi et al.,2007; Theumer et al., 2008; Weibking et al., 1994). These studies gave fairly different results (Table1). In contrast with the two other studies, Orsi et al. (2007) observed an increased Sa/So ratio inurine of animals exposed to AF alone. Both, Orsi et al. (2007) and Weibking et al. (1994)demonstrated an antagonistic interaction between AF and FB on the Sa/So ratio in the liver and inthe serum of exposed animals. Conversely, Theumer et al. (2008) observed a synergistic effect of thetwo toxins when looking at the Sa/So ratio in the kidney, urine, and to a lesser extent in the serumand the liver of exposed rats. Of note, this study also described a synergistic interaction in theincidence and the severity of kidney and liver lesions (Theumer et al. 2008).25