Effects of Prenatal Ethanol Exposure on the Postnatal Development of the Brainstem Auditory Evoked Potential in the Rat

Abstract

Brainstem auditory evoked potentials (BAEPs) were used to study the postnatal development of the peripheral and brainstem auditory pathways in rat pups prenatally exposed to ethanol. Pups were offspring of dams receiving either a liquid diet containing ethanol (ethanol pups) or a control diet (control pups). Two to four pups from control and ethanol litters were systematically selected for BAEP analysis and examined periodically from the ages of 2 to 10 weeks. BAEPs to 0.1 msec clicks (60 dB HL, B/sec) were recorded with subcutaneous scalp electrodes in nonsedated animals. Latencies of the various BAEP waves decreased with age in both groups, reflecting maturation of the subcortical auditory pathway. Ethanol pups, however, showed retarded BAEP maturation as indicated by significantly longer BAEP wave latencies and smaller wave amplitudes than those of the control pups. While group differences were greatest early in development, the ethanol group still had significantly longer BAEP wave latencies at maturity. These results indicate that prenatal ethanol exposure retards development of the peripheral and brainstem auditory pathways and that prolonged auditory transmission times, despite a “catch‐up” trend, persist in maturity. BAEP data, birth weights, and postnatal weight gains of ethanol pups were not consistent with the effects of pre‐ and postnatal malnutrition as reported by others.