Deficits In Auditory Cortical Processing Induced By Early BPA Exposure In Rats

Chemicals that mimic the effects of endogenous hormones and thus interfere with endocrine function are collectively referred to as endocrine-disrupting chemicals（EDCs）.In recent years,there has been increasing concern about the effects of endocrine disruptor exposure on human health.According to the World Health Organization（WHO）,2,2-bis（4-hydroxyphenyl）propane（BPA）is an endocrine disruptor.This chemical with hormone-mimicking or antagonistic activity is used in the production of numerous consumer products,and there is a consensus that humans are widely and consistently exposed to this chemical.Previous studies have shown that BPA exposure can have a wide range of effects on brain structure and function,and that developmental exposure to BPA can impair learning and cognitive function in both animals and humans.The primary sensory system is involved in the development of cognitive functions and is the first to mature in the cortex,yet it is largely unknown whether BPA affects the development of the primary sensory system.In this study,we investigate the possible effects of BPA exposure during lactation on behavioral and cortical neural processing of temporal rates of sound in rats.We found that（1）BPA-exposed rats exhibited significant behavioral deficits in performing sound repetition rate discrimination tasks;（2）large-scale alterations in frequency and temporal processing were also recorded in the primary auditory cortex（A1）of BPA-exposed rats,as evidenced by reduced frequency selectivity and diminished rate-following ability of neurons;（3）the recorded postexposure effects were accompanied by changes in densities and maturity of the dendritical spines in A1;and（4）expression in activity-regulated cytoskeletonassociated（ARC）protein was also down-regulated in A1 after BPA exposure.These findings in the animal model demonstrate that BPA has detrimental effects on auditory cortical processing and auditory-related behavior（particularly in the temporal domain）.They suggest that the effects of early exposure to endocrine disruptors such as BPA on human health merit a more careful examination.