title: Establishment of a transgenic sickle-cell mouse model to study the pathophysiology of priapism.
abstract: BACKGROUND
  Priapism is a poorly understood disease process with little information on the etiology and pathophysiology of this erectile disorder. One group of patients with a high prevalence of priapism is men with sickle-cell disease.
  
  
  OBJECTIVE
  Establish an in vivo transgenic sickle-cell mouse model to study the pathophysiology of sickle-cell disease-associated priapism.
  
  
  METHODS
  Transgenic sickle-cell disease mice, expressing human sickle hemoglobin, were utilized. Three groups of mice were used: (i) wild type (WT), (ii) sickle-cell heterozygotes (Hemi), and (ii) sickle-cell homozygotes (Sickle). Two age groups of each cohort of mice were utilized: young adult (4-6 months) and aged (18-22 months).
  
  
  METHODS
  Histological (trichrome stain to measure ratio of collagen to smooth muscle), penile hydroxyproline content (collagen content), and transmission electron microscopic analysis of WT, Hemi, and Sickle mice penes, as well as in vivo erectile responses [change in intracavernous pressure (ICP)] to cavernous nerve stimulation (CNS), were determined. The frequency of erectile responses (erections/hour) pre- and poststimulation was also measured in each of the experimental groups.
  
  
  RESULTS
  Sickle mice had increased (P < 0.05) collagen to smooth muscle ratio and hydroxyproline content in the penis when compared with WT and Hemi mice penes. Transmission electron microscopy demonstrated thickened smooth muscle cell bundles, disruption of the endothelial lining of the corporal sinusoids, and increased (P < 0.05) caveolae number. Sickle mice had significantly (P < 0.05) higher ICP to CNS and increased (P < 0.05) frequency of erections pre- and post-CNS when compared with WT and Hemi mice erectile responses. Sickle mice did develop ED (change in ICP in response to CNS) with increasing age.
  
  
  CONCLUSIONS
  The morphometric changes of the penis and exaggerated in vivo erectile responses support the use of this transgenic sickle-cell disease animal model to study the pathophysiological mechanisms involved in sickle-cell disease-associated priapism.
authors.affiliation: The James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors.forename: Trinity J
authors.initials: TJ
authors.lastname: Bivalacqua
authors.forename: Biljana
authors.initials: B
authors.lastname: Musicki
authors.forename: Lewis L
authors.initials: LL
authors.lastname: Hsu
authors.forename: Mark T
authors.initials: MT
authors.lastname: Gladwin
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Burnett
authors.forename: Hunter C
authors.initials: HC
authors.lastname: Champion
mesh_terms: D000704:Analysis of Variance; D000755:Anemia, Sickle Cell / Q000150:complications*; D000818:Animals; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D005355:Fibrosis / Q000503:physiopathology; D007511:Ischemia / Q000503:physiopathology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009569:Nitric Oxide; D010410:Penile Erection; D010413:Penis / Q000503:physiopathology*; D011317:Priapism / Q000209:etiology / Q000503:physiopathology*
chemical_list: D009569:Nitric Oxide