Effects of Prenatal Styrene Exposure on Postnatal Development and Brain Serotonin and Catecholamine Levels in Rats

Maternal reproductive effects in Wistar rats exposed to 0, 50, or 300 ppm styrene for 6 h/day during gestational days 6 to 20 were evaluated. Their offspring were observed postnatally for neurochemical changes, growth, and physical landmarks of development. Mothers exposed to styrene were compared with pair-fed and ad-lib-fed controls in order to adjust nutrient conditions. Prolongation of the gestational period, food intake, and the number of neonatal deaths or stillbirths in 300-ppm-exposed dams showed evidence of styrene-related effects. Other reproductive parameters, such as litter size, birth weight, and sex ratio, were found to exhibit no effects within the variation range studied. A neurochemical effect was observed in that the 5-HT and HVA concentrations in cerebrum were significantly decreased. Incisor eruption (mandible), eye opening, and the air-righting reflex were delayed in rat pups born to dams receiving 300 ppm styrene exposure compared with the pair-fed and ad lib control groups. Pups born to dams exposed to 50 ppm styrene also had a significantly delayed air-righting reflex compared with ad lib controls. These results suggest that the offspring were susceptible to the effects of styrene on a few developmental landmarks even when nutritional effects were controlled.