Sympathetic nervous system as transmitter of mechanical loading in bone

• Published in: Joint, bone, spine : revue du rhumatisme Vol. 70; no. 6; pp. 515 - 519
• Main Authors: Levasseur, Régis, Sabatier, Jean-Pierre, Potrel-Burgot, Céline, Lecoq, Bertrand, Creveuil, Christian, Marcelli, Christian
• Format: Journal Article
• Language: English
• Published: France Elsevier SAS 01.12.2003
• Subjects: Absorptiometry, Photon; Adrenergic beta-Antagonists - pharmacology; Animals; Biomechanical Phenomena; Bone and Bones - drug effects; Bone and Bones - innervation; Bone and Bones - physiology; Bone Density - drug effects; Bone Density - physiology; Bone mineral density; Bone Resorption - physiopathology; Female; Hind limb unloading; Mechanical load; Models, Animal; Osteogenesis - drug effects; Osteogenesis - physiology; Propranolol; Propranolol - pharmacology; Rats; Rats, Wistar; Sympathetic nervous system; Sympathetic Nervous System - physiology; Mechanical load; Hind limb unloading; Bone mineral density; Sympathetic nervous system; Propranolol
• ISSN: 1297-319X
• DOI: 10.1016/j.jbspin.2003.07.006

Sympathetic innervation has been demonstrated in bone. Adrenergic stimulation is one of the transmitters of bone loss by uncoupling between decreased bone formation and increased bone resorption. Objective. – By using a non-specific antagonist of β-adrenergic pathway (propranolol per os), we hypothesized that we could rescue the uncoupling induced mechanical unloading bone loss in the rat model of tail-suspension. Materials and methods. – Twenty-two female Wistar rats, 12 week-old, have been divided into three groups: eight tail-suspended rats (SR), six tail-suspended rats treated by propranolol (SRP) and eight non-suspended rats (NSR) during 30 days. Bone mineral density (BMD, g/cm 2) has been measured by DXA (Hologic QDR-4500A) at D0 and D30 of the study, in the distal femoral metaphysis (DFM), the femoral diaphysis (FD), the whole body (WB, g) and body composition. Results. – Between D0 and D30, in DFM a significant variation in BMD is observed between NSR and SR (% BMD change: NSR +15.6 ± 3.1% vs SR –1.0 ± 1.4%, P < 0.0001) and BMD rescue in SRP group (% BMD change SRP +5.3 ± 1.5% vs SR –1.0 ± 1.4%, P = 0.03). In FD, gain of BMD is significant in NSR compared to SR (+17.5 ± 1.5% vs +8.2 ± 2.8%, P = 0.007) and to SRP (+17.5 ± 1.5% vs +10.1 ± 2.4%, P = 0.046). Gain in SRP group is not significant compared to SR group ( P = 0.6). In WB, SRP gain more BMD than NSR (+14.0 ± 1.8% vs +5.4 ± 0.7%, P = 0.0002) and than SR (+14.0 ± 1.8% vs +7.8 ± 1.4%, P = 0.0043). There is no difference between NSR and SR groups ( P = 0.19). Conclusion. – We demonstrate that β-adrenergic pathway of sympathetic nervous system is a major transmitter pathway of mechanical loading in rat bone. A specific study is necessary to analyse a possible systemic effect of propranolol in rat bone. Propranolol could be used to prevent the induced mechanical unloading bone loss as weightlessness.