Effects of Noise Exposure on the Volume of Adrenal Gland and Serum Levels of Cortisol in Rat

Background: noise pollution is considered as a stressful factorin every day's life of the industrial world. the presentstudy was designed to investigate the probable effects of differenttime exposure of noise stress on histomorphometricchanges of adrenal gland, plasma cortisol and body weight ofthe rat.methods: sixty adult male wistar rats were divided into twoseries of short time noise or stne exposure (n=20) for oneday and long time noise exposure or ltne (n=40) for 30 dayswith a sound intensity of 100 dba. ltne series were furtherdivided into five groups of control, sham, 4, 8 and 12-hrsnoise exposure and stne series were divided into four groupsof the same as ltne except sham group. the cortisol assaywas performed on blood samples of pre and post treatmentwith noise in two series and cavalieri methods in a stereologicalstudy for determination of adrenal volume changes only inltne series.results: the results showed that the mean plasma cortisol level(5.4(plus-minus)3.2 ug/dl in lnte-8hrs and 4.9(plus-minus)1.8 ug/dl in lnte12hrs),the volumes of cortex (7.08(plus-minus)1.31 mm' in lnte-8h and7.12(plus-minus)1.31 mm' in lnte-12h), medulla (0.68(plus-minus)0.19 mrrr' inlnte-8h) of adrenal gland increased. the mean animal weightdid not show any significant changes.conclusion: sound pollutions can increase the stress hormonelevel and cause increasing the volume of adrenal gland thatmay be related to the effect of noise on the hypothalamuspituitary-adrenal axis. these results may be important to increasingof many disorders such as cardiovascular diseases inindustrial societies.