Results of the NCTR Collaborative Behavioral Teratology Study (CBTS)*

Abstract

Abstract Behavioral measures used in the CBTS were negative geotaxis, olfactory discrimination, auditory startle habituation, 1‐hr and 23‐hr activity, an operant discrete trial discrimination task, and activity following amphetamine challenge. Body weights and certain physical landmarks of development also were monitored in two separate studies, one using prenatal treatment with 0, 0.5 or 2.0 mg/kg d‐amphetamine sulfate sc on gestation days 12‐15, the other using 0, 2.0 or 6.0 mg/kg methylmercuric chloride by gavage on gestational days 6‐9. An untreated control group also was included in each study. The CBTS design allowed evaluation of reproducibility and detection sensitivity of these methods, as well as the impact of early testing experience on later assessments, offspring sex differences in response levels and variability, and the contribution of litter‐to‐litter variation to behavioral measures used in this standardized protocol. Results obtained at the six participating laboratories are discussed in relation to each of these factors and to the degree of overt toxicity obtained with each compound. Behavioral data were reproducible, and detection sensitivities of the tests were very good, requiring no more than 5‐25% change from control values for either sex. Early testing experience was not found to be a major factor in determining later behavioral levels, but litter was found to contribute considerable variability to all physical and behavioral data.