Abstract: Objective To investigate the effect of postnatal music exposure on fearful behavior of prenatal stressed rats in defensive withdrawal test and the expression of gastrin-releasing peptide receptor (GRPR) in the amygdala. Methods Wistar pregnant rats were divided in stress group (n=8) and control group (n=8). The stress group were immobilized and bright lighted 45 min, 3 times a day, when gestation 11-20 days, while the control group without any stress. The new born rats from the stress group were exposed in music (SM group) or white noise (SW group) for 45 min twice a day since 1 day after born, and the rats from the control (SC) group left undisturbed. They were tested with defensive withdrawal test 60 days after birth, and the GRPR levels in the amygdala were measured with immunofluorescence and real-time PCR. Results The latency was shorter and the frequence out of the chamber was the most in the SM group of the defensive withdrawal test (P<0.001), while GRPR-positive cells and GRPR mRNA increased in amygdala (P<0.001). Conclusion Postnatal music exposure can counteract the abnormal behavior response of prenatal stressed offspring and accompany with increased expression of GRPR in the amygdala.

Key words: prenatal stress, music exposure, gastrin-releasing peptide receptor, amygdala, defensive withdrawal test, rats