Effects of tower climbing exercise on bone mass, strength, and turnover in orchidectomized growing rats

Abstract

To determine the effects of a tower climbing exercise on mass, strength, and local turnover of bone, 70 9-wk-old Sprague-Dawley rats were assigned to seven groups: a baseline control and three groups of sham-operated sedentary, orchidectomized (ORX)-sedentary and ORX-exercise rats. Rats voluntarily climbed a 200-cm tower to drink water from a bottle set at the top. At 4 wk, the periosteal bone formation rate (BFR), moment of inertia, bone mineral content, bone mineral density, and bending load at the midfemur were maintained in ORX-exercise rats, whereas these parameters were reduced in ORX-sedentary rats. At 8 wk, the periosteal mineral apposition rate and BFR in ORX-exercise rats were significantly higher, whereas the parameters in ORX-sedentary rats did not differ compared with sham-sedentary rats. In ORX-exercise rats, the trabecular mineralizing surface, BFR, and bone volume of the lumbar vertebrae were maintained at the same levels as those in the sham-sedentary group, whereas the osteoclast surface decreased compared with the ORX-sedentary group. However, the climbing exercise did not affect bone mineral content, bone mineral density, or the compression load of the lumbar vertebrae. These results show that, in the midfemur, the voluntary climbing exercise maintained cortical bone mass and strength by stimulating periosteal bone formation and partially prevented ORX-induced trabecular bone loss, depressing the elevation of turnover. Interestingly, in ORX rats, the climbing exercise had the opposite effect on bone formation at the periosteal femoral cortical bone, where the exercise increased the bone formation compared with vertebral trabecular bone, where the exercise decreased it.

Sex steroids during bone growth: a comparative study between mouse models for hypogonadal and senile osteoporosis

“…Indeed, daughters of female patients with hip fractures have an enlarged femoral neck, suggesting that bone fragility-in humans similar to this senile osteoporosis model-may already become apparent during growth [28,29]. In line with earlier studies in rats, early hypogonadism causes a sustained cancelllous bone deficit as well as an increase in bone resorption markers in both SAMP6 and SAMR1 [17]. Yet, earlier reports in SAMP6 mice could not demonstrate an upregulation of osteoclast formation and activity after orch [12,13].…”

“…Androgens are essential for the development of a male skeletal phenotype during growth. Similar to humans, hypogonadism in rodents, as induced by orchidectomy at puberty, results in low bone mass acquisition as well as low bone strength [15][16][17]. Orchidectomy in male rodents reduces periosteal bone formation and increases bone turnover, hereby impairing, respectively, cortical and trabecular bone mass acquisition [18].…”

Orchiectomized Fischer 344 male rat models body composition in hypogonadal state

“…A substantial increase in bone resorption occurred, but only a small decrease in muscle mass and no increase in fat mass. In male Sprague-Dawley rats, ORX causes a significant reduction in strength (Brown et al, 2001), with no change in muscle mass (Wolden-Hanson et al, 1989;Notomi et al, 2002;Iwamoto et al, 2003). Similarly, ORX does not decrease muscle mass in Wistar rats (Antonio et Life Sciences 79 (2006) 411 -415 www.elsevier.com/locate/lifescie al., 1999Ferry et al, 1999).…”

Effects of Voluntary Resistance Exercise and High-protein Snack on Bone Mass, Composition, and Strength in Rats Given Glucocorticoid Injections

“…Voluntary tower climbing is a light resistance exercise that creates little stress and strain and has been used in several studies. 5,9,[14][15][16][17] We previously demonstrated that voluntary tower climbing exercise increased bone mass and strength mainly by increasing bone formation in growing, 10) orchidectomized, 15) or ovariectomized osteopenic rats.…”

“…7) Animal exercise models are used to examine the preventive or recovery eŠect of exercise on bone mass and strength as endpoints of an experiment. Animal studies using voluntary wheel running, 11) jumping, 12) treadmill running, 13) or voluntary climbing 9,14,15) have demonstrated the beneˆcial eŠect of increased load on bone mass and mechanical properties. Voluntary tower climbing is a light resistance exercise that creates little stress and strain and has been used in several studies.…”