Perinatal Exposure to the Fungicide Prochloraz Feminizes the Male Rat Offspring

Abstract

Prochloraz is a commonly used fungicide that has shown multiple mechanisms of action in vitro. It antagonizes the androgen and the estrogen receptors, agonizes the Ah receptor, and inhibits aromatase activity. In vivo prochloraz acts antiandrogenically in the Hershberger assay by reducing weights of reproductive organs, affecting androgen-regulated gene expressions, and increasing luteinizing hormone (LH) levels. The purpose of this study was to investigate reproductive toxic effects after exposure during gestation and lactation to prochloraz alone and a mixture of five pesticides (deltamethrin, methiocarb, prochloraz, simazine, and tribenuron-methyl). Prochloraz (30 mg/kg/day) or the mixture (20 mg/kg/day) was dosed to pregnant Wistar dams from gestational day (GD) 7 until postnatal day (PND) 16. Some dams were taken for cesarean section at GD 21, and others were allowed to give birth. Results showed that prochloraz and the mixture significantly reduced plasma and testicular testosterone levels in GD 21 male fetuses, whereas testicular progesterone was increased. Gestational length was increased by prochloraz. Chemical analysis of the rat breast milk showed that prochloraz was transferred to the milk. In males a significant increase of nipple retention was found, and the bulbourethral gland weight was decreased, whereas other reproductive organs were unaffected. In addition cytochrome P450 (CYP)1A activities in livers were induced by prochloraz, possibly as a result of Ah receptor activation. Behavioral studies showed that the activity level and sweet preference of adult males were significantly increased. Overall these results strongly indicate that prochloraz feminizes the male offspring after perinatal exposure, and that these effects are due, at least in part, to diminished fetal steroidogenesis.

Widely Used Pesticides with Previously Unknown Endocrine Activity Revealed as in Vitro Antiandrogens

“…There is insufficient evidence to assess the risk of tested pesticides to human health because of a lack of data. However, to our knowledge, all of the pesticides (with the possible exception of fenitrothion; Okahashi et al 2005;Turner et al 2002) identified as in vitro AR antagonists in our study have also been reported to have anti androgenic effects in vivo in animal models (Anway et al 2006;Gray et al 1999;Lambright et al 2000;McIntyre et al 2002;Ostby et al 1999;Sinha et al 2001;Taxvig et al 2007;Uzumcu et al 2004;Vinggaard et al 2005). We also identified 7 compounds that appeared to be androgenic because they stimulated activity in the absence of DHT.…”

“…These compounds are newly formulated fungicides (dimethomorph, 2007; fludioxonil, 2008; fenhexamid, 2001), which are stable on food commodities (> 70% of the parent compound) and remain unchanged on the commodity when reaching the consumer (EFSA 2007(EFSA , 2010a(EFSA , 2010b. Dimethomorph and fenhexamid belong to the fungicide group of sterol bio synthesis inhibitors (Leroux 2004), as do the in vivo anti androgenic conazoles (e.g., Taxvig et al 2007) and imidazoles (Vinggaard et al 2005). A study of the sterol biosynthesis inhibitors imazalil, propi conazole, triadimefon, triadimenol, and prochloraz indicated that all inhibited aromatase in human placental microsomes (Vinggaard et al 2000), but to our knowledge, effects of dimethomorph and fenhexamid on steroido genesis in mammalian cells have not been assessed.…”

“…A study of the sterol biosynthesis inhibitors imazalil, propi conazole, triadimefon, triadimenol, and prochloraz indicated that all inhibited aromatase in human placental microsomes (Vinggaard et al 2000), but to our knowledge, effects of dimethomorph and fenhexamid on steroido genesis in mammalian cells have not been assessed. Imazalil and the in vivo anti androgen prochloraz (Vinggaard et al 2005) are both classified as imidazole fungicides, and in vitro potency estimates for the two compounds were similar (IC 20 : imazalil, 3.23 μM; prochloraz, 2.39 μM), but the possible effects of imazalil in vivo have not been evaluated. Therefore, it is our view that dimethomorph, fludioxonil, fenhexamid, and imazalil should be tested in vivo as a matter of urgency.…”

“…There is a good correlation between androgen receptor (AR) antagonist properties and in vivo anti androgenic effects, and there is also good evidence that androgen-sensitive end points are demasculinized in male rats when exposed in utero to a wide range of pesticides. Antiandrogenic effects both in vitro and via maternal exposure in vivo have been reported in response to the herbicide linuron Lambright et al 2000); the fungicides prochloraz (Vinggaard et al 2005), procymidone (Ostby et al 1999), tebuconazole (Taxvig et al 2007), and vinclozolin (Anway et al 2006;Uzumcu et al 2004); the organochlorine insecticides DDE ) and endosulfan (Sinha et al 2001); the organophosphate dimethoate (Verma and Mohanty 2009); and the pyrethroid insecticide deltamethrin (Andrade et al 2002). However, with the exception of linuron, dimethoate, deltamethrin, and tebuconazole, the pesticides listed above have not been authorized for use in Europe during the past 5 years, which should result in lower occupational, residential, and dietary exposures.…”

Applicability of Computational Systems Biology in Toxicology

“…Prochloraz is a widely used pesticide that has been demonstrated to have endocrine activity. In animals, it has been shown to cause adverse reproductive outcomes in the male offspring after exposure during foetal life [35][36][37][38]. Prochloraz is known to demasculinize male rat foetuses and virilize female foetuses; however, as clinical studies of environmental chemicals are not carried out, little is known about human effects of this compound.…”