The effects of neonatal ethanol and/or cocaine exposure on isolation-induced ultrasonic vocalizations

Isolation-induced ultrasonic vocalizations (USVs) are emitted by young rat pups when isolated from their dam and conspecifics. These USVs play an impo rtant role in maternal/offspring interactions, and have been used as an ind icator of response to stress and isolation. This study examined the effects of neonatal ethanol and/or cocaine exposure on USVs in neonatal rats. The neonatal exposure paradigm serves as a model for the "human third trimester of pregnancy" in terms of CNS development. There were five treatment group s including an artificially reared (AR) ethanol-exposed group (6 g/kg/day), an AR cocaine-exposed group (60 mg/kg/day), an AR ethanol- and cocaine-exp osed group (6 g/kg/day + 60 mg/kg/day), an AR isocaloric control, and a nor mally reared control. Both groups that received ethanol took longer to voca lize, and displayed fewer vocalizations than non-ethanol-exposed pups when tested on clean bedding (Experiment 1) or on chips from the nest of a lacta ting dam (Experiment 2). These results suggest that neonatal ethanol exposu re alters the pup's immediate response to isolation. This could have direct effects on maternal/infant interactions, and might help explain some of th e long-term effects of ethanol exposure on social behaviors. (C) 2000 Elsev ier Science Inc. All rights reserved.