EFFECTS OF PRENATAL EXPOSURE TO A LOW DOSE ATRAZINE METABOLITE MIXTURE ON THE REPRODUCTIVE DEVELOPMENT OF MALE LONG EVANS RATS

The chlorotriazine herbicide atrazine (ATR) is one of the two most abundantly applied herbicides in the United States. A previous study utilizing a cross-foster paradigm showed that gestational and/or lactational exposure to ATR results in reproductive tract alterations in male Long-Evans (LE) rats, including delayed preputial separation (PPS) and increased lateral prostate weight and inflammation. Chlorotriazine herbicides are rapidly metabolized in plants and animals and gestational exposure to a low-dose mixture of ATR and its metabolites, diaminochlorotriazine (DACT), hydroxyatrazine (HA), deethylatrazine (DEA), and deisopropylatrazine (DIA), has been associated with developmental effects in postnatal female offspring in LE rats. The present study examines the potential for alterations in reproductive development in male offspring following gestational exposure to an atrazine metabolite mixture (AMM). The mixture consisted of ATR (25% by molar equivalent), DACT (35%), HA (20%), DEA (15%), and DIA (5%) and was formulated based upon combined maximum ATR and metabolite concentrations reported in ground and surface water (estimated at 25 ppb). Pregnant LE rats were dosed by gavage with the AMM at 0.09, 0.87, 8.73 mg AMM/kg body weight (BW)/d, on gestation days 15–19, using 0 and 100 mg ATR/kg BW/d as negative and positive controls, respectively. In control males, preputial separation (PPS) occurred at 41.8 ± 0.3 d and BW at PPS was 228.0 ± 3.8 g. PPS was delayed only in the 100 mg ATR/kg BW/d prenatally exposed (PE) males (43.3 ± 0.4 d, p = 0.05) and BW at PPS was increased in the 0.87 mg AMM/kg BW/d PE males (246.3 ± 4.5 g, P < 0.05). During necropsy, 25% of males in the 0.87 mg AMM/kg BW/d treatment group and 21% of males in the 8.7 mg AMM/kg BW/d treatment group exhibited external nodules of the lateral prostate lobes, which were observed in less than 5% of control males. Epididymal fat pad lipomas were present in 20% and 23% of males in the same treatment groups, respectively, while observation of lipomas in control males was again less than 5%. The ventral prostate weight from 8.7 mg AMM/kg BW/d PE males (0.409 ± 0.019 g) was significantly less at postnatal day (PND) 120 than those of control males (0.465 ± 0.019 g, p = 0.05). Histologic examination of the prostate glands indicated no significant increase in distribution or severity of inflammation. However, there was an apparent increase in the incidence of inflammation in the ventral prostate of males in the 0.87 and 8.7 mg AMM/kg BW/d exposure groups compared to controls. Immunohistochemical staining of the ventral prostate revealed no significant change in the presence of proliferating cell nuclear antigen (PCNA) in treated males compared to controls at PND 120. To determine if there was an association between prostate inflammation and serum cytokine levels of 120-day old rats, 12 cytokines were measured in a multiplex format with ELISA-based fluorescent detection. There was no dose-dependent difference, but interleukins 1alpha, 6, 12p70, and interferon-gamma were elevated in 0.09 and 8.7 mg AMM/kg BW/d PE males. These results suggest that gestational exposure to a low-dose AMM can affect reproductive development in male LE rats and that the effects observed differ from those following prenatal exposure to higher doses of atrazine alone (This abstract does not necessarily reflect EPA policy). (platform)