Role of Testosterone on Bone Maintenance in Orchidectomized Rats

Abstract

There has been much recent interest in the relationship between androgens and bone mineralization in men. Increase in serum androgens during puberty allow for skeletal maturation and the attainment of peak bone mass and the persistence of normal testosterone secretion during adulthood is important for the maintenance of bone density. Testosterone deficiency is associated with heightened bone turnover and is a major risk factor for osteoporosis in men. In the light of this, animal models for male bone loss are desirable, and can add further investigations on the possibility of testosterone replacement, with testosterone deficiency under natural or surgical conditions. So, this study examined the effect of castration and testosterone substitution on male albino rats, through several biochemical aspects and also histological features and their relationship to bone. Five groups of adult male rats were used group I used as a control intact group II and IV used as orchidectomized control, and groups III and V served asorchidectomized treated with testosterone oenanthate and proponate at dose levels 500 ug and 3000ug/ 100 g/ week for seven weeks respectively. Body weight and the relative organs weight of femur, tibia and brain were declined significantly after castration, with testosterone replacement some enhancement was achieved to different extents according to the dose level. Calcium content in bones (femur and tibia) and serum was reduced significantly after castration with hormonal replacement a remarkable improvement was found. Phosphorous content showed a marked increase in bones and serum post orchidectomy with hormonal treatment the values were declined. Serum 1.25 dihydroxy vitamin D3 decreased significantly in castrated groups and with testosterone treatment an amelioration was observed according to the dose level. The concentration of testosterone follicle stimulating hormones (FSH), luteinizing hormone (LH) and prolactin changed significantly after castration, thus testosterone and prolactin were reduced, while FSH were elevated markedly. After the treatment by testosterone an improvement was achieved with different levels, but the two goandotropins (FSH & LH) were still in low level as compared to control intact. The histological studies revealed that orchidectomy affected greatly the bone consistency. Sections of epiphyseal plate of castrated rats revealed disarray in the arrangement of chondrocytes and ossification stages. Pyknotic nuclei in the chondrocytes were greatly encountered in the proliferative zone, and the thin septa between the chondrocytes rows approximately disappeared in most of the area. On the other hand, the diaphysis structure of castrated rats appeared without histopathological changes. After treatment with testosterone an amelioration appeared with different levels, but the high dose was more effective.