Collaborative Behavioral Teratology Study: results.

Behavioral measures used in the Collaborative Behavioral Teratology Study (CBTS) were negative geotaxis (PNDs 7-10), olfactory discrimination (PNDs 9-11), auditory startle habituation (PNDs 18-19 and 57-58), 1-hr activity (PNDs 21, 60, 100 and 120), 23-hr activity (PND 100), activity following a pharmacological challenge (PND 120), and an operant, discrete trial visual discrimination task. Maternal and offspring body weights and the appearance of certain physical landmarks of development were also monitored. The design of the CBTS allowed evaluation of the reproducibility and detection sensitivity of these behavioral test methods, as well as the impact of early testing experience on later behavioral assessment, offspring sex differences in response levels and variability, and the contribution of litter-to-litter and animal-to-animal variation to behavioral measures in a standardized test protocol. The results obtained in this test system are discussed in relation to each of these factors and to the degree of overt toxicity obtained using prenatal treatment with 0, 0.5 or 2.0 mg/kg d-amphetamine sulfate, SC, on gestation days 12-15 (Study 1) or methylmercuric chloride, 0, 2.0 or 6.0 mg/kg by gavage, on gestation days 6-9 (Study 2).