Sex and strain differences in the developmental activity profile of rats prenatally exposed to sodium salicylate.

Pregnant Sprague-Dawley (CD) and Long-Evans (LE) rats were treated by gavage on days 8-10 of gestation with either 0, 125 or 175 mg/kg/day sodium salicylate. Locomotor activity was monitored repeatedly for 30 min in the offspring on postnatal days 12, 16, 20, 24, 30, 60, 90 and 120 in the presence or absence of olfactory cues from home cage bedding. Prenatal exposure during organogenesis to the doses of sodium salicylate used here resulted in subtle alterations in developmental locomotor activity, the pattern of which was dependent on sex, strain and bedding condition during testing. Many more dose-related changes in activity were found in LE rats and, with one exception, these were decreased levels in treated rats. All significant dose-related differences in CD rats were increased activity levels in treated animals relative to controls. Male rats showed more dose-related changes in activity than did females, and activity testing conducted in the absence of home cage bedding cues resulted in a clearer distinction of treatment-related changes than did testing in the presence of home cage bedding. These results suggest a behavioral teratogenic effect of sodium salicylate. In addition, they point out the subtle nature of many behavioral effects in the absence of more overt toxicity and the impact factors such as strain, sex and procedural variables may have on the conclusions drawn from these studies.