title: Growth Hormone Therapy Accelerates Axonal Regeneration, Promotes Motor Reinnervation, and Reduces Muscle Atrophy following Peripheral Nerve Injury.
abstract: BACKGROUND
  Therapies to improve outcomes following peripheral nerve injury are lacking. Prolonged denervation of muscle and Schwann cells contributes to poor outcomes. In this study, the authors assess the effects of growth hormone therapy on axonal regeneration, Schwann cell and muscle maintenance, and end-organ reinnervation in rats.
  
  
  METHODS
  Male Sprague-Dawley rats underwent sciatic nerve transection and repair and femoral nerve transection without repair and received either daily subcutaneous growth hormone (0.4 mg/day) or no treatment (n = 8 per group). At 5 weeks, the authors assessed axonal regeneration within the sciatic nerve, muscle atrophy within the gastrocnemius muscle, motor endplate reinnervation within the soleus muscle, and Schwann cell proliferation within the denervated distal femoral nerve.
  
  
  RESULTS
  Growth hormone-treated animals demonstrated greater percentage increase in body mass (12.2 ± 1.8 versus 8.5 ± 1.5; p = 0.0044), greater number of regenerating myelinated axons (13,876 ± 2036 versus 8645 ± 3279; p = 0.0018) and g-ratio (0.64 ± 0.11 versus 0.51 ± 0.06; p = 0.01), greater percentage reinnervation of motor endplates (75.8 ± 8.7 versus 38.2 ± 22.6; p = 0.0008), and greater muscle myofibril cross-sectional area (731.8 ± 157 μm versus 545.2 ± 144.3 μm; p = 0.027).
  
  
  CONCLUSIONS
  In male rats, growth hormone therapy accelerates axonal regeneration, reduces muscle atrophy, and promotes muscle reinnervation. Growth hormone therapy may also maintain proliferating Schwann cells in the setting of prolonged denervation. These findings suggest potential for improved outcomes with growth hormone therapy after peripheral nerve injuries.
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Sami H
authors.initials: SH
authors.lastname: Tuffaha
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Budihardjo
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Karim A
authors.initials: KA
authors.lastname: Sarhane
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Khusheim
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Diana
authors.initials: D
authors.lastname: Song
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Broyles
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Roberto
authors.initials: R
authors.lastname: Salvatori
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Means
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: James P
authors.initials: JP
authors.lastname: Higgins
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Jaimie T
authors.initials: JT
authors.lastname: Shores
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Damon S
authors.initials: DS
authors.lastname: Cooney
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Hoke
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: W P Andrew
authors.initials: WPA
authors.lastname: Lee
authors.affiliation: Baltimore, Md.|From the Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation Laboratory, and the Departments of Medicine and Neurology, Johns Hopkins University School of Medicine; and the Curtis National Hand Center.
authors.forename: Gerald
authors.initials: G
authors.lastname: Brandacher
mesh_terms: D000818:Animals; D001369:Axons; D004195:Disease Models, Animal; D013006:Growth Hormone / Q000494:pharmacology*; D008297:Male; D009046:Motor Neurons; D018482:Muscle, Skeletal / Q000294:innervation* / Q000473:pathology; D009133:Muscular Atrophy / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D059348:Peripheral Nerve Injuries / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D012584:Sciatic Nerve / Q000293:injuries*
chemical_list: D013006:Growth Hormone