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EFFECT OF ATRAZINE ON IMPLANTATION AND EARLY PREGNANCY IN FOUR STRAINS OF RATS
Citation:
Cummings, A M., B. E. Rhodes, AND R L. Cooper. EFFECT OF ATRAZINE ON IMPLANTATION AND EARLY PREGNANCY IN FOUR STRAINS OF RATS. TOXICOLOGICAL SCIENCES 58(1):135-143, (2000).
Description:
Atrazine (ATR) is an herbicide that has been shown to have adverse reproductive effects including alterations in levels of pituitary hormones such as prolactin (prl) and luteinizing hormone (LH). Since prl's action to promote progesterone secretion is essential for the initiation of pregnancy in rats, this study was designed to examine the effect of exposure to ATR during early pregnancy on implantation and short-term pregnancy maintenance. Rats were divided into two groups representing periods of dosing with ATR prior to the diurnal or nocturnal surges of prl. Within each group, four groups consisting of four strains of rats (Holtzman, HLZ; Sprague Dawley, SD; Long Evans, LE; Fisher 344, F344) were each further subdivided into four ATR dosages. Rats were dosed by gavage with 0, 50, 100, or 200 mg/kg/day ATR on days 1-8 of pregnancy (day 0 = sperm +). All animals were necropsied on day 8 or 9 of pregnancy. The 200 mg/kg dose of ATR reduced body weight gain in all but one group. Two groups of animals showed an increase in percent preimplantation loss, and both of these were F344 rats. Holtzman rats were the only strain to show a significant level of postimplantation loss and a decrease in serum progesterone. Alterations in serum LH were seen in several groups. Serum estradiol was significantly increased only in Sprague Dawley rats dosed at the diurnal interval with 200 mg/kg ATR. We conclude that F344 rats are most susceptible to preimplantation effects of ATR and that HLZ rats appear most sensitive to the postimplantation effects of the chemical. LE and SD rats were least sensitive to effects of ATR during very early pregnancy.