Effects of noise exposure on the volume of adrenal gland and serum levels of cortisol in rat

Noise pollution is considered as a stressful factor in every day's life of the industrial world. The present study was designed to investigate the probable effects of different time exposure of noise stress on histomorphometric changes of adrenal gland, plasma cortisol and body weight of the rat. Sixty adult male Wistar rats were divided into two series of short time noise or STNE exposure [n=20] for one day and long time noise exposure or LTNE [n=40] for 30 days with a sound intensity of 100 dBA. LTNE series were further divided into five groups of control, sham, 4, 8 and 12-hrs noise exposure and STNE series were divided into four groups of the same as LTNE except sham group. The cortisol assay was performed on blood samples of pre and post treatment with noise in two series and Cavalieri methods in a stereological study for determination of adrenal volume changes only in LTNE series. The results showed that the mean plasma cortisol level [5.4 +/- 3.2 micro g/dl in LNTE-8 hrs and 4.9 +/- 1.8 micro g/dl in LNTE- 12 hrs], the volumes of cortex [7.08 +/- 1.31 mm[3] in LNTE-8h and 7.12 +/- 1.31 mm[3] in LNTE-12h], medulla [0.68 +/- 0.19 mm[3] in LNTE-8 h] of adrenal gland increased. The mean animal weight did not show any significant changes. Sound pollutions can increase the stress hormone level and cause increasing the volume of adrenal gland that may be related to the effect of noise on the hypothalamuspituitary- adrenal axis. These results may be important to increasing of many disorders such as cardiovascular diseases in industrial societies

[Study of anatomical position of termination of the spinal cord in different ages of male cat]

Objective: study of anatomical position of termination of the spinal cord in male cat

Animals: fifteen male cat in 2 prenatal groups of mid stage fetus [37d] and late stage fetus and 3 postnatal groups of newbom, sexually adult [6 m] and adult age [>ly/o] and 3 animals in each group

Procedure: fixation of spinal cord with injection of and suspension in 10% formalin, laminectomy of vertebral column and definition of spinal cone on related to vertebral column by pin

Results: the results indicated that, as in the mid and late stage fetuses, the spinal cord terminated at anterior one third of Co, and posterior one thud of S,, respectively but in newbom, sexually adult stage and adult age at posterior, middle and anterior one third of S2, respectively

Discution: thus with increase of age the terminal portion of spinal cord were more anterior and this showed that the vertebral column had been grown faster than that the spinal cord