Abstract
Zearalenone (ZEN) is a frequently-occurring mycotoxin in both animal and fish feeds. In order to characterize its effects on carp, three groups of fish were fed for 28 days with feeds contaminated with three different levels of ZEN (low: 332 µg kg−1, medium: 621 µg kg−1, and high: 797 µg kg−1 feed). The reversibility of the effects of ZEN was assessed by feeding all of the groups with uncontaminated feed for a further 14 days. Gene expression of immune genes in the liver tissue of the fish was analysed, revealing reduced expressions of immune, antioxidative, and estrogen-related genes after the fish had been exposed to ZEN. However, the expression of vacuole-type H+ ATPase increased substantially with ZEN exposure, thus supporting the previously-reported sensitivity of lysosomal functions to ZEN. Feeding the fish with a ZEN-free diet for a further two weeks changed the effects of ZEN on the expression of some genes, including the expressions of the cytokines IL-1β, IL-8, IL-10, and arginase 2, which were not influenced after four weeks of treatment, but showed lower values after the recovery phase in fish previously treated with ZEN compared with the control group. In summary, this study confirmed the broad effects of ZEN on different essential functions in carp and suggests that the current maximum allowable levels in compound feed are too high to prevent damage to fish.
Highlights
The mycotoxin zearalenone (ZEN)frequently occurs in feed stuffs and ingredients [1,2,3].In addition to hepatotoxic, genotoxic, haematological, and reproduction effects [4,5,6,7,8] of ZEN on fish, concern relating to the effects of this fungal metabolite on the immune system is increasing.Many mycotoxins are assumed to be immunotoxic in higher vertebrates [9]
To expand our knowledge of the systemic actions of ZEN in fish, the present study examined the effects of ZEN on the mRNA expression of selected genes in carp (Cyprinus carpio), which is an important fish species for aquaculture [34]
The relative mRNA levels of pro-inflammatory and anti-inflammatory immune-related genes were assessed in liver from control and ZEN-fed carp after 28 days of experimental feeding (Figures 1 and 2)
Summary
The mycotoxin zearalenone (ZEN)frequently occurs in feed stuffs and ingredients [1,2,3].In addition to hepatotoxic, genotoxic, haematological, and reproduction effects [4,5,6,7,8] of ZEN on fish, concern relating to the effects of this fungal metabolite on the immune system is increasing.Many mycotoxins are assumed to be immunotoxic in higher vertebrates [9]. The mycotoxin zearalenone (ZEN)frequently occurs in feed stuffs and ingredients [1,2,3]. Dietary exposure to ZEN has been shown to impair immune functions in domestic and laboratory animals [10,11,12,13,14]. This has included impairment of both innate and acquired immune responses [15,16]. The effects of ZEN on the immune parameters of fish have rarely been investigated. Recent publications have reported changes in white blood cell populations [7] and immunomodulation in carp treated with ZEN for four weeks [8], but the mechanism of action of ZEN remains unknown
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