2-hydroxyatrazine and propazine

We showed previously that the chlorotriazine herbicide, atrazine (ATR), delays the onset of pubertal development in female rats. ATR and its biotransformation by-products are present in soil and groundwater. Since current maximum contaminant levels are set only for ATR, it is important to determine whether these by-products can also alter pubertal development and possibly pose a cumulative exposure hazard. We evaluated the effects of two ATR by-products, diamino-s-chlorotriazine (DACT) and hydroxyatrazine (OH-ATR), and a structurally similar chlorotriazine, propazine (PRO), on female pubertal development. Rats were gavaged from postnatal days (PNDs) 22 through PND 41 with DACT (16.7, 33.8, 67.5, 135 mg/kg), OH-ATR (22.8, 45.7, 91.5, 183 mg/kg), or PRO (13, 26.7, 53, 106.7, 213 mg/kg). The dose range for each chemical was selected as the molar equivalent of ATR (12.5, 25, 50, 100, 200 mg/kg). The females were monitored daily for vaginal opening (VO) and killed on PND 41. DACT, a by-product of ATR that occurs in the environment and is also the primary chlorinated metabolite of ATR in animal tissue, delayed VO by 3.2, 4.8, and 7.6 days compared to the controls (33.1 +/- 0.4 (SE) days of age) following exposure to 33.8, 67.5, and 135 mg/kg, respectively. The no effect level (NOEL) for DACT (16.7 mg/kg) was identical to the equimolar NOEL for ATR (25 mg/kg). Although the body weight (BW) on PND 41 was reduced by the high dose of DACT (8.4% reduction), this reduction did not exceed the criteria for selecting the maximum tolerated dose (e.g., a dose that causes >10% decrease in BW at necropsy). None of the lower doses of DACT caused a significant difference in BW gain. Additionally, 33.8, 67.5, and 135 mg/kg of DACT significantly increased the BW on the day of VO. PRO (107 or 213 mg/kg) delayed VO by 4 days but did not alter the BW on PND 41. While no significant delays in pubertal development were observed in two separate dose-response studies with doses ranging up to 183 mg/kg (OH-ATR), a minor but statistically significant delay in the onset of puberty in a pilot study using OH-ATR raises the possibility that an effect might occur following exposure to higher doses. However, it is clear from these data that OH-ATR has a much lower potency when compared with equimolar doses of DACT and PRO. Together, these data demonstrate that PRO and DACT can delay the onset of puberty in the female rat at doses equimolar to ATR and provide the scientific basis for the use o

Topics: Administration, Oral; Animals; Atrazine; Biotransformation; Body Weight; Female; Herbicides; No-Observed-Adverse-Effect Level; Organ Size; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Rats, Wistar; Sexual Maturation; Thyroid Hormones; Triazines; Vagina

The effects of four major chlorotriazine metabolites on the constitutive synthesis of the catecholamines dopamine (DA) and norepinephrine (NE) were examined, using undifferentiated PC12 cells. NE release and intracellular DA and NE concentrations were quantified, for up to 24 h after initiation of treatment with different concentrations, ranging from 0 to 400 microM, of the metabolites hydroxyatrazine (HA), 2-amino-4-chloro-6-isopropylamino-s-triazine (deethylchlorotriazine), 2-amino-4-chloro-6-ethylamino-s-triazine (deisopropylchlorotriazine), and diaminochlorotriazine (DACT). Hydroxyatrazine significantly decreased intracellular DA and NE concentrations in a dose- and time-dependent manner. This metabolite also caused a significant inhibition of NE release from the cells. In contrast, deethylchlorotriazine and deisopropylchlorotriazine significantly increased intracellular DA concentration following exposure to 50-200 microM from 12 to 24 h. Intracellular NE was significantly reduced at these same concentrations of deethylchlorotriazine at 24 h while the concentration of NE in PC12 cells exposed to deisopropylchlorotriazine was not altered at any dosage or time point measured. NE release was decreased at 18 (200 microM) and 24 h (100 and 200 microM) following exposure to deethylchlorotriazine and at 24 h (100 and 200 microM) following deisopropylchlorotriazine. DACT, at the highest concentration (160 microM), significantly increased intracellular DA and NE concentrations at 18 and 24 h. NE release was also increased at 40-160 microM at 24 h. The viability of the PC12 cells was tested using the trypan blue exclusion method. Following 18 to 24 h of treatments with HA, cell viability was reduced 10-12% at the two higher concentrations (200 and 400 microM), but, with other metabolites, the viability was reduced by only 2 to 5% at the highest concentrations. These data indicate that HA affects catecholamine synthesis and release in PC12 cells in a manner that is similar to synthesis of atrazine and simazine. On the other hand, deethylchlorotriazine and deisopropylchlorotriazine altered catecholamine synthesis in a manner similar to that observed in the rat brain following in vivo exposure (i.e., increased DA and decreased NE concentration), whereas DACT appeared to produce an increase in NE release as well as in the intracellular DA and NE concentrations. Overall, these findings suggest that the catecholamine neurons may be a target for the chlorotriazines a

Topics: Animals; Atrazine; Cell Survival; Dopamine; Herbicides; Norepinephrine; PC12 Cells; Rats; Triazines