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Thursday 21 December 2006

Doping dose of Salbutamol and exercise: deleterious effect on cancellous and cortical bones in adult rats.

By: Bonnet N, Benhamou CL, Beaupied H, Laroche N, Vico L, Dolleans E, Courteix D.

J Appl Physiol 2006 Dec 21; [Epub ahead of print]

Animal studies suggest that bone remodelling is under beta-adrenergic control via the sympathetic nervous system. To our knowledge, the impact of doping beta2 agonist substances, at doping doses, has never been studied on adult rats. The purpose of this study was to examine the effects of Salbutamol injections without exercise or combined with treadmill exercise on trabecular and cortical bone in adult rats. Adult female Wistar rats (36 weeks of age, n=56) received a subcutaneous injection of Salbutamol (SHAM SAB, 3mg/kg/day, 5 days/week) or vehicle (SHAM) with or without subsequent treadmill exercise (13m/min, 60min/day, 5 days/week) for 10 weeks. Tibial and femoral BMD were analyzed by Dual energy X-ray Absorptiometry. At death, microcomputed tomography was performed to study metaphysic trabecular bone structure. Histomorphometric analysis was performed to assess bone cell activities. After 10 weeks, SAB rats presented a lower BMD increase (SAB: +3.3% vs SHAM: +12.4%, p<0.05), an alteration of the trabecular parameters and an increased bone resorption compared to the control group. The negative effect on bone architecture in SAB-treated groups persisted even with treadmill exercise. These results confirm the deleterious effect observed during chronic treatment, of beta2 agonists on bone mass, and describe its consequences on bone mechanical properties in adult rats. Bone loss occurred independently of SAB-induced muscle mass anabolism and was equally severe in sedentary and exercising rats, despite a beneficial effect of exercise on the extrinsic and intrinsic energy to ultimate. These bone effects may have important consequences in athletes using Salbutamol as doping substance. Key words: ss2 agonist, bone, exercise, histomorphometry, doping.

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