title: Sympathetic nervous system as transmitter of mechanical loading in bone.
abstract: 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 -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.
  
  
  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/cm2) 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).
  
  
  CONCLUSIONS
  We demonstrate that -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
authors.affiliation: Service de Rhematologie, CHU Cote de Nacre, Cannes, France.levasseur-r@chu-caen.fr
authors.forename: Régis
authors.initials: R
authors.lastname: sseur
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Sabatier
authors.forename: Céline
authors.initials: C
authors.lastname: Potrel-Burgot
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lecoq
authors.forename: Christian
authors.initials: C
authors.lastname: Creveuil
authors.forename: Christian
authors.initials: C
authors.lastname: Marcelli
mesh_terms: D015502:Absorptiometry, Photon; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D001862:Bone Resorption / Q000503:physiopathology*; D001842:Bone and Bones / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D005260:Female; D023421:Models, Animal; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol