Receptor-bound ligand was separated using 2 ml of ethanol and radioactivity (dpm) was determined using [3H] counting on a Beckman LS5000TD liquid scintillation counter.
Timed-pregnant Sprague-Dawley rats (approximately 90 days of age) were purchased from Charles River Laboratories (Raleigh, NC).
Forty-eight rats (bred 9 September 2002) were used in the main study and 12 rats (bred 17 June 2002) were used in a preliminary dose range-finding study. Dams were delivered to Environmental Protection Agency facilities on Gestational Day (GD) 2 (the day after insemination was considered GD 1) and housed in transparent, 20 X 25 X 47 cm polycarbonate cages with laboratory-grade, heat-treated pine shavings (Northeastern Products, Warrensburg, NY). Animals were housed with a 14L:10D photoperiod (lights off at 1100 h) at 20-24°C and 40%-50% relative humidity. Dams were fed Purina Rat Chow 5008 ad libitum. Weaned pups were fed Purina Rat Chow 5001. Animals had 24-h access to filtered (5 |xm) drinking water from the Durham, NC municipal supply.