Identification of a Novel Hemoglobin Adduct in Sprague Dawley Rats Exposed to Atrazine

Dooley, Greg; Prenni, Jessica E.; Prentiss, Pilar L.; Cranmer, Brian K.; Andersen, Melvin E.; Tessari, John D.

doi:10.1021/tx060023c

Cited by 20 publications

(22 citation statements)

References 33 publications

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“…These data suggested that ATR is perhaps the primary compound that acutely affects the brain and that metabolism of ATR, at least in terms of its acute effects on the brain, is a detoxication mechanism. However, recent reports indicated that both ATR and DACT can covalently react with proteins forming stable protein adducts (Dooley et al, 2006(Dooley et al, , 2008. Several proteins were identified in these studies that were adducted by DACT, but the functional consequence of this adduction is currently unknown.…”

Section: Ross Et Almentioning

confidence: 99%

“…Thus, some of the effects of ATR exposure on the thymus may be indirect, i.e., mediated by activation of the stress axis, which is observed after acute ATR exposure (Pruett et al, 2003). On the other hand, because ATR and DACT were detectable in the spleen, their ability to form protein adducts (Dooley et al, 2006(Dooley et al, , 2008 may play a role in the longerlasting effects of ATR exposure on the spleen (Filipov et al, 2005).…”

Section: Ross Et Almentioning

confidence: 99%

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Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels

Ross¹,

Jones²,

Filipov³

2008

Drug Metab Dispos

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2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine, ATR)is a toxicologically important and widely used herbicide. Recent studies have shown that it can elicit neurological, immunological, developmental, and biochemical alterations in several model organisms, including in mice. Because disposition data in mice are lacking, we evaluated ATR's metabolism and tissue dosimetry after single oral exposures (5-250 mg/kg) in C57BL/6 mice using liquid chromatography/mass spectrometry (Ross and Filipov, 2006). ATR was metabolized and cleared rapidly; didealkyl ATR (DACT) was the major metabolite detected in urine, plasma, and tissues. Plasma ATR peaked at 1 h postdosing and rapidly declined, whereas DACT peaked at 2 h and slowly declined. Most ATR and metabolite residues were excreted within the first 24 h. However, substantial amounts of DACT were still present in 25-to 48-h and 49-to 72-h urine. ATR reached maximal brain levels (0.06-1.5 M) at 4 h (5-125 mg/kg) and 1 h (250 mg/kg) after dosing, but levels quickly declined to <0.1 M by 12 h in all the groups. In contrast, strikingly high concentrations of DACT (1.5-50 M), which are comparable with liver DACT levels, were detectable in brain at 2 h. Brain DACT levels slowly declined, paralleling the kinetics of plasma DACT. Our findings suggest that in mice ATR is widely distributed and extensively metabolized and that DACT is a major metabolite detected in the brain at high levels and is ultimately excreted in urine. Our study provides a starting point for the establishment of models that link target tissue dose to biological effects caused by ATR and its in vivo metabolites.Atrazine (ATR) is a triazine herbicide that effectively inhibits photosynthesis in broadleaf weeds and grasses (Environmental Protection Agency, 2003). In the United States, ATR is applied on crops such as corn, sugarcane, pineapples, macadamia nuts, and sorghum, as well as on highway and railroad rights-of-way and on evergreen trees (Environmental Protection Agency, 2003). Several epidemiological studies have investigated the link between ATR exposure and adverse human health outcomes (Hoppin et al., 2002;MacLennan et al., 2002;De Roos et al., 2003;Hessel et al., 2004). However, the human data at present are equivocal. In some cases ATR exposure is associated with negative health outcomes, whereas in others it is not. One major drawback of virtually all the existing epidemiological studies is the fact that ATR exposure has not been precisely quantified or estimated. In this regard, exposure-only studies, i.e., studies where health outcomes have not been assessed, indicate that pesticide applicators and farmers during spraying are exposed to appreciable levels of ATR because detectable amounts of ATR and its metabolites are found in their saliva and urine (Hines et al., 2006). Moreover, a recent report indicated that not only ATR applicators but also their families are at risk of high level of ATR exposure (Curwin et al., 2007).Although data on health effects of ATR in humans ar...

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Section: Ross Et Almentioning

confidence: 99%

Section: Ross Et Almentioning

confidence: 99%

Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels

Ross¹,

Jones²,

Filipov³

2008

Drug Metab Dispos

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“…Despite its relatively short half-life in the adult rat (< 1 day), many laboratories have shown that ATR administration adversely affects the endocrine system and reproductive tissue development in the rat (reviewed by Dooley et al 2006). Long-term dietary exposure to 400 ppm ATR (~ 22.5 mg/kg) caused an early onset of mammary tumors in Sprague-Dawley rats, and the appearance of tumors was mediated by ATR-induced premature reproductive aging (Eldridge et al 1994b, 1998, 1999a, 1999b).…”

mentioning

confidence: 99%

Mammary Gland Development as a Sensitive End Point after Acute Prenatal Exposure to an Atrazine Metabolite Mixture in Female Long-Evans Rats

Enoch

Stanko

Greiner

et al. 2007

Environ Health Perspect

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BackgroundAtrazine (ATR), a widely used chlorotriazine herbicide, inhibits a number of endocrine-dependent processes, including gonadotrophin surges and mammary gland development in rats. Chlorotriazine herbicides are rapidly metabolized in plants and animals to form a group of metabolites that are detected both in the environment and in exposed animals. The extent to which these metabolites are responsible directly for the observed health effects is not understood.ObjectivesOur goal was to determine if a mixture of ATR metabolites, in proportions found in the environment, might produce developmental effects in Long-Evans rats following exposure late in pregnancy.MethodsWe administered an ATR metabolite mixture (AMM) containing ATR, hydroxyatrazine, diaminochlorotriazine, deethylatrazine, and deisopropylatrazine orally to pregnant Long-Evans rats at 0.09, 0.87, or 8.73 mg/kg body weight (bw)/day, on gestation days 15–19, using 0 and 100 mg ATR/kg bw/day as negative and positive controls, respectively.ResultsWe observed no significant effect of acute AMM exposure on body weight gain in dams during the dosing period, weight loss in pups on postnatal day (PND)4, or pubertal timing, as is seen with ATR alone. However, as with ATR, we detected delayed mammary gland development, evaluated by whole mount analysis, as early as PND4 in all treatment groups.ConclusionsOur data suggest that acute exposure to AMM at levels as low as 0.09 mg/kg bw during late pregnancy causes persistent alterations in mammary gland development of female offspring, and that these effects do not appear to be related to bw or associated with pubertal timing.

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“…DACT is reactive towards exposed cysteine residues in vitro forming stable covalent adducts through a non-enzymatic nucleophilic substitution reaction at the chlorine moiety. 20 Numerous DACT-adducted proteins have been identified in the pituitary and hypothalamus in previous studies with ATRA exposed rodents suggesting widespread protein modification. 14,21 Nearly all of the identified modified proteins share the common characteristic of exposed cysteine residues.…”

Section: Discussionmentioning

confidence: 97%

The atrazine metabolite diaminochlorotriazine suppresses LH release from murine LβT2 cells by suppressing GnRH-induced intracellular calcium transients

Dooley

Tjalkens²,

Hanneman³

2013

Toxicol. Res.

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The primary metabolite of the herbicide atrazine (ATRA), diaminochlorotriazine (DACT), has been suggested to cause disruption in the hypothalamic-pituitary-gonadal axis leading to inhibition of luteinizing hormone (LH) release. DACT is a reactive electrophile known to form covalent protein adducts both in vitro and in vivo following ATRA exposure and maybe targeting proteins involved in GnRH-induced calcium signaling and subsequent LH release. To test this hypothesis, LβT2 pituitary cells were exposed to 300 μM DACT for 24 hrs and examined by fluorescence microscopy for GnRH-induced changes in intracellular calcium and LH release. LβT2 cells exposed to DACT had markedly diminished GnRH-induced intracellular calcium transients and a significant decreased LH release in response to GnRH. DACT appeared to cause a selective decrease in caffeine-sensitive ryanodine receptor-operated calcium stores in LβT2 cells, rather than in thapsigargin-sensitive ER calcium stores. This sensitivity correlated with the formation of covalent protein adducts by DACT, as determined by mass spectrometry. ERp57 was identified by mass spectrometry as a target of DACT adduction in the ER that could potentially mediate the effects of DACT on inhibition of GnRH-induced calcium signaling and inhibition of LH release. Intracellular calcium responses to GnRH and release of LH were restored in DACT-treated cells with the addition of a calcium ionophore (A23187). These data suggest that DACT forms adducts on proteins involved in calcium handling within the ER and that dysfunction in this critical signaling system is associated with loss of normal sensitivity to GnRH and subsequent decreased release of LH.

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Identification of a Novel Hemoglobin Adduct in Sprague Dawley Rats Exposed to Atrazine

Cited by 20 publications

References 33 publications

Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels

Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels

Mammary Gland Development as a Sensitive End Point after Acute Prenatal Exposure to an Atrazine Metabolite Mixture in Female Long-Evans Rats

The atrazine metabolite diaminochlorotriazine suppresses LH release from murine LβT2 cells by suppressing GnRH-induced intracellular calcium transients

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