title: Response of Rat Tibia to Prolonged Unloading Under the Influence of Electrical Stimulation at the Dorsal Root Ganglion.
abstract: OBJECTIVE
  Immobilization of weight bearing skeletons or microgravity results in disuse osteoporosis in both human and animals. Our previous study demonstrated that electrical stimulation at the dorsal root ganglion (DRG) with an implantable micro-electrical stimulation system (IMESS) could trigger secretion of bone anabolic calcitonin gene-related peptide (CGRP) and prevent bone loss in a short-term hindlimb unloading rat model. This study was designed to further investigate whether electrical stimulation to the DRG could prevent bone loss due to prolonged unloading.
  
  
  METHODS
  Eighteen adult rats were randomly assigned into three groups: cage control (CC), hindlimb unloading (HU), and hindlimb unloading with electrical stimulation (HUES). Electrical stimulation was applied via IMESS to the right DRGs at vertebral levels L4-L6 in HUES group for 6 weeks.
  
  
  RESULTS
  Following unloading for 6 weeks, proximal tibia metaphysis was shown 64.0% decrease in bone mineral content (BMC) and 47.0% decrease in bone mineral density (BMD) in HU group while significant reduced bone lose with 2.7% increase in total BMC and only 9.2% decrease in total BMD in HUES group. Diaphyseal BMD decreased significantly in both HU and HUES group as compared with CC group. There was enhancement of CGRP expression in the DRGs in HUES group.
  
  
  CONCLUSIONS
  This experimental study proved the proposed concept using electrical stimulation at the DRG for prevention of disuse-induced bone loss in a rat hindlimb suspension model.
authors: Department of Rehabilitation Sciences, the Hong Kong Polytechnic University, Hong Kong, SAR, China.
authors: Roy
authors: R
authors: Yuen-Chi Lau
authors: School of Aerospace, Tsinghua University, People's Republic of China.
authors: Xing
authors: X
authors: Qian
authors: Department of Rehabilitation Sciences, the Hong Kong Polytechnic University, Hong Kong, SAR, China.
authors: Kai-Ting
authors: KT
authors: Po
authors: School of Aerospace, Tsinghua University, People's Republic of China.
authors: Lu-Ming
authors: LM
authors: Li
authors: Department of Rehabilitation Sciences, the Hong Kong Polytechnic University, Hong Kong, SAR, China.
authors: Xia
authors: X
authors: Guo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D001847:Bone Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000628:therapy*; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods; D005500:Follow-Up Studies; D005727:Ganglia, Spinal / Q000502:physiology*; D019417:Hindlimb Suspension / Q000009:adverse effects; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000000981:diagnostic imaging / Q000378:metabolism*; D013997:Time Factors; D015898:Tomography Scanners, X-Ray Computed
chemical_list: D015740:Calcitonin Gene-Related Peptide
keywords: Dorsal root ganglion; disuse osteoporosis; electrical stimulation; immobilization; microgravity