title: Effect of aging on expression of nitric oxide synthase I and activity of nitric oxide synthase in rat penis.
abstract: OBJECTIVE
  To investigate the effect of aging on the expression of nitric oxide synthase I (NOS I) and the activity of NOS in rat penis.
  
  
  METHODS
  Sixty male rats from 3 age groups (adult, old and senescent) were investigated. The expression of NOS I protein and mRNA in rat penis were detected by Western blot and RT-PCR respectively and the NOS activity, with ultraviolet spectrophotometry.
  
  
  RESULTS
  In the old and senescent group, NOS I protein expression was significantly decreased as compared with the adult. NOS I mRNA expression was well correlated with the protein expression. NOS activity was not statistically different between the adult and old groups, but it was significantly reduced in the senescent compared with the adult group (P<0.01).
  
  
  CONCLUSIONS
  The aging-induced decreases in NOS I expression and NOS activity may be one of the main mechanisms leading to erectile dysfunction in the senescent rats.
authors.affiliation: Department of Andrology, Shenyang Andrology Hospital, 32, Beiling Street, Shenyang 110032, China. doctor.man@163.net
authors.forename: Jun-Ping
authors.initials: JP
authors.lastname: Shi
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Zhao
authors.forename: Yu-Tong
authors.initials: YT
authors.lastname: Song
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D008297:Male; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D010413:Penis / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat