In utero and lactational exposure to ammonium perchlorate in drinking water: effects on developing deer mice at postnatal day 21.

The effects of in utero and lactational exposure to ammonium perchlorate (AP), a component of rocket fuel and a thyroid toxicant, on developing deer mice (Peromyscus maniculatus) were evaluated. Breeding pairs were dosed continuously with 0, 1 nM, 1 micro M, or 1 mM AP in drinking water, from cohabitation until pups were euthanized at postnatal day (PND) 21. Pups from the second litter were used for evaluation in this study. No significant differences were observed in any analysis performed when litter means were used in statistical analysis. All reported significant differences occurred when statistical analysis was performed on individual pup data. Body weights were significantly different between treatments at PND 5 and PND 20, with the 1- micro M body weights being lower than that of controls. Body weight and liver weight in the 1-mM group were significantly higher than the 1- micro M weights at PND 21 when analyzed by analysis of variance (ANOVA). However, there were no significant differences in liver weights when analyzed with body weight as the covariate. Heart weights were significantly different between males and females. Male heart weights in the 1- microM and 1-mM groups were significantly lower than in controls when analyzed by analysis of covariance (ANCOVA) with body weight as the covariate. Litter size and survival percentage were not significantly different among treatments. Although significant differences were observed only when the individual pup was used as the experimental unit, these data suggest that AP exposure at different concentrations may variably alter body weight and male heart weight during mammalian development.

Effects of in utero and lactational ammonium perchlorate exposure on thyroid gland histology and thyroid and sex hormones in developing deer mice (peromyscus maniculatus) through postnatal day 21.

Thyroid gland hormone levels and histology and sex hormone levels in developing deer mice (Peromyscus maniculatus) were measured following in utero and lactational exposure to ammonium perchlorate (AP), a component of rocket fuel and a thyroid toxicant. Breeding pairs were dosed continuously with 0, 1 nM, 1 micro M, or 1 mM concentrations of AP in drinking water from the time of cohabitation until pups from the third litter were weaned. Pups from the second litter were used for evaluation in this study. The active (colloid-containing) thyroid follicle number per unit area was significantly different between treatment groups. The 1-nM and 1-mM treatment groups had significantly fewer active follicles per unit area than did controls. The 1-mM treatment group also had significantly fewer active follicles than the 1- micro M and the 1-nM treatment groups. Total T(4) concentrations were significantly increased in the 1-nM and 1- micro M groups compared to the controls. No significant difference was observed in total T(3) concentrations. None of the 1-mM plasma had concentrations of total testosterone above the detection limit, and only one of the 1- micro M samples was above the detection limit of the assay. All estradiol concentrations were below the detection limits of the assay. In contrast to the situation in adult rodents, it appears that AP increases thyroid hormone production in developing deer mice and produces variable effects with increasing concentrations.