Timed pregnant rats

Timed-pregnant rats were dosed with l.Opg TCDD/kg on GD14. One day after birth, litters were cross-fostered to produce control, placental-only, lactational-only, and placental/lactational exposure groups. The DTH response to BSA was assessed in 5-month-old males. In these rats the severity of the suppression of the DTH response was related to the route of TCDD exposure (i.e., placental/lactational > lactational > placental), with suppression occurring only in the males receiving both placental and lactational exposure.128 In order to determine the lowest maternal dose of TCDD required to suppress the DTH response in pups, dams were dosed with 0.1,0.3, or l.Opg TCDD/kg on GD14 and the DTH response to BSA was evaluated in 4- and 14-month-old pups. In the males, suppression was observed at a maternal dose of O.lpg TCDD/kg at 14 months of age, while a maternal dose of 0.3pg TCDD/kg was required to cause suppression in... 

The timed pregnant rats are used to sample gestation day (GD) 9 embryos on the day of the whole embryo culture (WEC) assay. The rats are typically shipped -GD4-5 and allowed to acclimate in the animal room for 4-5 days prior to initiating the culture experiment. 

Bioavailabihty and B(a)P disposition studies conducted in timed pregnant rat dams have demonstrated a progressive increase in plasma and cortex metabolite concentrations in offspring pups as a function of B(a)P aerosol exposure concentration. Additionally, differences in metabolite disposition from plasma to cortex within individual exposure concentration cohorts were noted. No detectable levels of B(a)P metabolites are ever in the control (carbon-black exposed Hood et al, 2000) rats as reported in Wu et al. 

Following single dermal applications of 10 mg/kg of radiolabeled methyl parathion to pregnant rats, methyl parathion was found to be widely distributed to all major tissues and organs. Concentrations were highest in plasma and kidney, maximum levels measured 2 hours postapplication. Peak levels in liver, brain, fetus, and placenta, were measured 2 to 10 hours later, at which times the highest concentration of methyl parathion was in the fetus (Abu-Quare et al. 2000). 

Administered to pregnant rats by inhalation 7 hours/day on days 1-19 of gestation, 8000 ppm caused reduced fetal weights, an increased incidence of skeletal malformations, and significant maternal toxicity in the form of narcosis and reduced feed consumption." At 3 500 ppm for the same exposure time, there were no fetal or maternal effects. 

Animals Time-mated pregnant rats at an age of 9-10 weeks at the time of breeding. The range of rat body weight is 200-225 g. 

Corticosteroid type activity. Seed oil, administered parenterally to pregnant rats, was active. The survival time of adrenalecto-mized pregnant rats and their subsequent litters was increased " ". ... 

Half of the fetuses in each pregnant rat on the 19th gestational day were injected with 3 micrograms thyroxine (circles) and the other half with saline (crosses). They were killed at the difference pre- or postnatal times indicated by the abscissa, and cytochrome c reductase (ordinate) was quantified. 

Reproductive toxicology studies are conducted to reveal the effect of the drug candidate on mammalian reproduction and whether potential reproductive risks may exist for humans. These reproductive studies commonly use pregnant rats and rabbits as the test species. To ensure that the dams and the fetuses are appropriately exposed to the drug candidate and metabolites (11), the dams can be dosed with radiolabeled compound, and the amount of radioactivity that crosses the placenta and into the fetuses at various times after dosing can be... 

We routinely use nose-only inhalation exposure of B(a)P aerosol to evaluate the consequence of prenatal exposure to this toxicant on physiological and behavioral endpoints. The properties of this B(a)P aerosol are shown in Figure 17.4. The aerosol typically exhibits a trimodal distribution with a 93% cumulative mass less than 5.85 pm, 89% cumulative mass less than 10 pm, 55.3% cumulative mass less than 2.5 pm, and 38% less than 1 pm. Fifty-five percent of the aerosol generally has a cumulative mass less than PM2.5 and the mass median aerodynamic diameter (MMAD) + geometric standard deviation for this mode is consistently 1.7 =E 0.085 pm. For several years we employed a rat model exposing timed pregnant dams to inhalation concentrations of 25, 75, and 100 pg/m. ... 

Cerivastatin caused a significant increase in incomplete ossification of the lumbar center of the vertebrae in rats at an oral dose of 0.72 mg kg Cerivastatin did not cause any anomalies or malformations in rabbits at oral doses up to 0.7 mg kg These doses resulted in plasma levels about six times the human exposure (Cmax free) for rats and three times the human exposure for rabbits (Cmax free) at a human dose of 0.8 mg. Cerivastatin crossed the placenta and was found in fetal liver, gastrointestinal tract, and kidneys when pregnant rats were given a single oral dose of 2 mg kg... 

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