title: Effects of insulin-like growth factor-1 on the relaxation responses of the cavernous smooth muscle from aged rats.
abstract: OBJECTIVE
  The aim of this study was determine whether intracavernosal injection (ICI) of insulin-like growth factor-1 (IGF-1) protein can improve corpus cavernosal smooth muscle relaxation in aging rats.
  
  
  METHODS
  Ten young (4-month-old) and 30 old (24-month-old) Sprague-Dawley male rats were enrolled in the study. The old rats were divided into three groups: vehicle-only (n = 10), IGF-1 1 µg/kg (n = 10) and IGF-1 10 µg/kg treatment groups (n = 10). After 4 weeks of single IGF-1 injection treatment, strips of corporal tissue were precontracted with phenylephrine, and dose-response curves were generated to evaluate endothelial-dependent [acetylcholine (ACh)], endothelial-independent [sodium nitroprusside (SNP)] and electrical field stimulation (EFS) vasoreactivity. The changes in percentage of cavernosal smooth muscle and the concentration of nitric oxide (NO) in penile tissue were also evaluated.
  
  
  RESULTS
  After IGF-1 treatment, the vasoreactivity was significantly improved in both the 1 µg/kg and the 10 µg/kg treatment groups compared with the vehicle-only group at 4 weeks in response to ACh, SNP and EFS (all p < 0.05). The percentage of cavernosal smooth muscle was increased in the IGF-1 treatment groups. The NO concentrations were increased after IGF-1 treatment.
  
  
  CONCLUSIONS
  These data demonstrate that ICI of IGF-1 can improve vasoreactivity via endothelium-dependent and endothelial-independent mechanisms in the corpus cavernosum of the aging rat.
authors: Departments of 1 Urology.
authors: Zhan-Ping
authors: ZP
authors: Xu
authors: Huai-Peng
authors: HP
authors: Wang
authors: Jiu-Min
authors: JM
authors: Liu
authors: Xiang-Guang
authors: XG
authors: Zheng
authors: Dan
authors: D
authors: Wu
authors: Xiao-Yong
authors: XY
authors: Pu
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D007273:Injections, Intramuscular; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D023421:Models, Animal; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D010413:Penis / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside; D009569:Nitric Oxide; D007334:Insulin-Like Growth Factor I; D000109:Acetylcholine
keywords: Cavernosal smooth muscle; insulin-like growth factor-1; intracavernosal injection; rats; vasoreactivity