Alterations in sensorimotor development: relationship to postnatal alcohol exposure.

The sensory, motor, and physical development of rats reared by dams, artificially reared on milk formula alone, or on milk formula combined with alcohol was examined. The rats given alcohol received 6.6 g/kg/day, which was administered either as 12 fractions distributed uniformly over 24 hours and resulted in stable blood alcohol concentrations (BACs) of 85 mg/dl, or condensed into 4 fractions over 8 hours and resulted in maximum and minimum BACs of 411 mg/dl and 45 mg/dl, respectively. Pups were reared artificially from postnatal days 4 to 12 with alcohol exposure occurring on days 4 to 10. A sensorimotor test battery was then administered from postnatal day 12 to postnatal day 30. The condensed alcohol exposure resulted in age-dependent hyperactivity, a delay in tooth eruption, disruption of balance and of the ability to use the hindlimbs in a coordinated fashion, and a delay in the acquisition of the midair righting reflex. The midair righting reflex also was disrupted by uniform alcohol exposure. Thus, postnatal alcohol exposure that produces high BACs causes more severe developmental aberrations than the same daily dose administered in a pattern producing low BACs.