Fate of [3H]-Deoxynivalenol in Rainbow Trout (Oncorhynchus mykiss) Juveniles: Tissue Distribution and Excretion

Abstract

Deoxynivalenol (DON), a Fusarium mycotoxin, is one of the most prevalent mycotoxins in aquafeeds. The toxicokinetics of DON are rarely studied in aquatic species. The present study used juvenile rainbow trout (Oncorhynchus mykiss) with a mean initial body weight of 7.72 ± 1.42 g in order to evaluate the pharmacokinetic behaviour and the metabolization of radiolabelled DON ([ 3 H]-DON). In a first trial, 30 fish were tube-fed with four pellets containing a total of 125 ± 0.019 ng of [ 3 H]-DON. At different sampling time points after feeding (1 h, 3 h, 6 h, 12 h or 24 h), the tissue distribution of the [ 3 H]-DON was assessed by liquid scintillation counting. In a second trial, five fish were tube-fed four pellets containing a total of 663 ng of unlabelled-DON. Twenty-four hours after feeding, metabolites of DON excreted into the water were analysed by LC-MS/MS. [ 3 H]-DON was detected in fish liver one hour after tube-feeding, indicating a rapid absorption of DON. In the first hour, [ 3 H]-DON achieved its maximum in the gastro-intestinal tract (GIT) (20.56 ± 8.30 ng). However, 6.19 ± 0.83 ng of [ 3 H]-DON was also detected in the water at this sampling time point. The fast excretion of [ 3 H]-DON (above the average gastric emptying time of trout) might be related to its high-water solubility and consequent excretion with the fluid phase of the chyme. The amount of [ 3 H]-DON in the GIT was stable during the first six hours. Such long transit time of DON through the GIT increases the potential for damage and absorption. The period between six and twelve hours seems to be the turning point in terms of DON excretion. Twelve hours after tube-feeding, the trout excreted 50.71 ± 22.17% of the tube-fed DON amount into water, while at the previous sampling time point (six hours) only 11.03 ± 6.09% were detected. These data suggest that an effective method for gastrointestinal DON detoxification in trout requires a period of action lower than six hours. In the present trial, no DON metabolites were detected in water.

The Occurrence of Mycotoxins in Raw Materials and Fish Feeds in Europe and the Potential Effects of Deoxynivalenol (DON) on the Health and Growth of Farmed Fish Species—A Review

“…An in vivo experiment with rainbow trout confirmed metabolisation of DON to the less toxic DON-3sulfate, possibly explaining the absence of clinical signs with high doses of DON [119]. In general, also in fish, DON and its metabolites are readily excreted via the bile and thereby finally via the faeces [146]. Studies have shown almost negligible accumulation of DON in the muscle of salmon [108,147], carp [125] and gilthead sea bream [147], indicating little risk to humans after consumption of farmed fish fillet.…”

Toxicokinetics of Deoxynivalenol in Dezhou Male Donkeys after Oral Administration

“…Different animals vary in their susceptibilities to DON in the order of pigs, mice, rats and poultry, which may be related to the different in absorption, distribution, metabolism and excretion of DON in animals [14]. Meanwhile, the toxicokinetics of DON have been studied on different kinds of animals, including pigs [15], chickens [16], mice [17], rats [18] and fish [19]. The time to reach the maximum plasma DON concentration (T max ) after oral administration was about 0.08-0.5 h in mice [20,21], 2 h in chicken [22] and 10 min in rats [23].…”

Mycotoxins in aquafeeds : The impact on rainbow trout

“…Further studies had also confirmed the impact of DON on rainbow trout productivity; either by using low DON doses (1100 and 2700 µg/kg) (Gonçalves et al, 2019) or high (4700 and 11400 µg/kg) (Gonçalves et al, 2018b). Notably, the latter study provided new insights into the direct effects of DON by measuring proteolytic enzyme activity and relevant gene expression in the head kidney, liver, brain and gastrointestinal tract.…”

“…An in vivo experiment with rainbow trout confirmed metabolisation of DON to the less toxic DON-3-sulfate, possibly explaining the absence of clinical signs with high doses of DON (Gonçalves et al, 2018b). In general, also in fish, DON and its metabolites are readily excreted via the bile and thereby finally via the faeces (Gonçalves et al, 2018b). Studies have shown almost negligible accumulation of DON in the muscle of salmon (Bernhoft et al, 2017;Nácher-Mestre et al, 2015), carp (Pietsch et al, 2014b) and gilthead sea bream (Nácher-Mestre et al, 2015), indicating little risk to humans after consumption of farmed fish fillet.…”

“…Also in fish, glucuronidation can transform DON to DON-3glucuronide (DON-3-GlcA), at least in in vitro studies of liver microsomes of carp and trout (Maul et al, 2012). An in vivo experiment with rainbow trout confirmed metabolisation of DON to the less toxic DON-3-sulfate, possibly explaining the absence of clinical signs with high doses of DON (Gonçalves et al, 2018b). In general, also in fish, DON and its metabolites are readily excreted via the bile and thereby finally via the faeces (Gonçalves et al, 2018b).…”