[Effect of vibration stress on the sexually dimorphic nucleus [SDN] of hypothalamus of immature male wistar rat]

ABSTRACT

The sexually dimorphic nuclei in the preoptic area [SDN-POA] of hypothalamus are a cluster of cells which size, shape and their cellular morphology are related to gender and age. Different stressors affect on hypothalamus nuclei. In this study, effect of vibration stress was studied on endocrine system and sexually dimorphic nucleus [SDN] of hypothalamus. In this experimental study, male immature Wistar rats [15 days old] were divided into 3 groups Control, Experimental E350 and E500. Experimental groups were exposed to vibration stress by shaker with frequency 350mot/min and 500mot/min, 15 minutes daily for 3 weeks. At the end of this period, serum plasmic hormones, such as cortisol, testosterone, estradiol and progesterone, were evaluated. Sections of the brain tissue were prepared for histological and microscopic studies. Cortisol levels increased significantly in experimental E350 [p<0.05] and E500 [p<0.001] groups. Testosterone level decreased significantly in experimental E500 [p<0.01] group. Progesterone increased significantly in experimental E500 [p<0.01]. Estradiol did not show a significant decrease. Microscopic studies of brain showed significant decrease of number and density of sexually dimorphic nuclei in the preoptic area [SDN-POA] of hypothalamus in male immature Wistar rats with vibration stress. Vibration stress induces dysfunction of hypothalamus-pituitary-adrenal axis which can lead to homosexuality and other sexually behavioral disorders