The Effect of Prenatal Stress on Auditory Brainstem Responses in Rat Pups

Recent epidemiological evidence indicates that the fetal environment can influence susceptibility to later disease during the lifespan. Prenatal stress exposure alters the programming of the metabolic and endocrine balance of various organs, including the auditory system. The current study aimed at evaluating how prenatal stress influences Auditory Brainstem Responses. Eighteen pregnant Wistar rats were stressed during a one-month gestation by chronic mild stress (CMS, a variable schedule of different stressors). After birth, the offspring’s hearing thresholds and latencies were evaluated and compared with the control group. The hearing thresholds were assessed by recording auditory evoked brainstem responses to 4, 8,12, and 16 kHz tone burst. The results showed that although CMS caused a significant increase in corticosterone in pregnant mothers, the offspring with CMS experience had significantly lower body weight than control animals (P < 0.00) yet there was no difference between hearing sensitivity of prenatally stressed offspring and the control group. However, ABRs showed a marked prolongation in wave II and IV latencies in prenatally stressed rats (P < 0.05). The current data confirmed that prenatal exposure to mild stress is not detrimental to hearing sensitivity. However, these data suggest that prenatal stress can affect the temporal processing of auditory stimuli in the brainstem.