Prenatal ethanol exposure impairs sensory processing and habituation of visual stimuli, effects normalized by postnatal environmental enrichment

Abstract

Background Individuals with fetal alcohol spectrum disorders (FASD) often show processing deficits in all sensory modalities. Using an operant light reinforcement model, we tested whether prenatal ethanol exposure (PE) alters operant responding to elicit a contingent sensory stimulus—light onset (turning on the light) and habituation to this behavior in rats. We also explored whether postnatal environmental enrichment could ameliorate PE‐induced deficits. Methods Pregnant Sprague Dawley rats were gavaged twice/day with 0 or 3 g/kg/treatment ethanol (15% w/v) during gestational days 8–20, mimicking second‐trimester heavy PE in humans. The offspring were reared in a standard housing condition or an enriched condition. Adult male and female offspring underwent an operant light reinforcement experiment with either a short‐access or a long‐access procedure. A dishabituation test was also conducted to characterize the habituation process. Results In the short‐access procedure, PE led to increased operant responding to the contingent light onset in both sexes reared in the standard housing condition. Such an effect was not observed in rats reared in enriched conditions due to an overall decrease in responding. Moreover, rats reared in enriched conditions showed greater short‐term habituation. In the long access procedure, PE rats showed increased responding and impaired long‐term habituation. The long‐access procedure facilitated both short‐term and long‐term habituation in control and PE rats. Conclusion Prenatal ethanol exposure increases responding to contingent light onset and impairs the long‐term habituation process. The PE‐induced deficits were ameliorated by rearing in the enriched environment and increasing the duration and frequency of exposure to light onset. The PE‐induced effects are like increased sensation‐seeking, a subtype of sensory‐processing deficit that is often observed in individuals with FASD. Our findings could inform a suitable animal model for investigating the underlying mechanisms and possible intervention strategies for sensory deficits in FASD.

Examining the effects of prenatal alcohol exposure on performance of the sustained attention to response task in children with an FASD

“…Consistent with auditory deficits in rats prenatally exposed to alcohol (Church, 1987 ; Church et al, 2012 ; Church & Gerkin, 1988 ) children with FASD also reveal altered auditory processing in children 3–6 years of age (Stephen et al, 2012 ). These findings align with multiple previous studies (Carr et al, 2010 ; Jirikowic et al, 2020 ; Margret et al, 2006 ; Wang et al, 2022 ) showing regionally distinct deficits in FASD compared to TDC in multiple sensory modalities.…”

The Fetal Alcohol Spectrum Disorders—An Overview of Experimental Models, Therapeutic Strategies, and Future Research Directions

“…The impaired habituation observed in PAE rats is consistent with sensory processing deficits. The study suggests that postnatal environmental enrichment can normalize the effects of prenatal ethanol exposure on sensory processing and habituation of visual stimuli in rats [160].…”

The Impact of Prenatal Alcohol Exposure on the Autonomic Nervous System and Cardiovascular System in Rats in a Sex-Specific Manner

“…Due to a moderate dose of ethanol, it was feasible to reduce the frequency of oral gavage administration from twice daily to once daily, decreasing the distress experienced by animals. Furthermore, the administration of thiamine via intramuscular injection was introduced to prevent thiamine deficiency [ 20 ]. Similarly, Burgess et al and Walton et al have already documented notable distinctions in cardiovascular system performance and cardiovascular responsiveness among male and female children [ 36 , 37 ].…”