title: Assessment of penile erection methods in rhesus macaques to model pharmacokinetics of antiretroviral drugs and penile infection with simian immunodeficiency virus.
abstract: BACKGROUND
  An established macaque model to assess HIV interventions against penile transmission is currently not available. Physiological changes during penile erections may affect susceptibility to infection and drug pharmacokinetics (PK). Here, we identify methods to establish erections in macaques to evaluate penile transmission, PK, and efficacy under physiologic conditions.
  
  
  METHODS
  Penile rigidity and length were evaluated in eight rhesus macaques following rectal electrostimulation (RES), vibratory stimulation (VS), or pharmacological treatment with Sildenafil Citrate (Viagra) or Alprostadil.
  
  
  RESULTS
  Rectal electrostimulation treatment increased penile rigidity (>82%) and length (2.5 ± 0.58 cm), albeit the response was transient. In contrast, VS alone or coupled with Viagra or Alprostadil failed to elicit an erection response.
  
  
  CONCLUSIONS
  Rectal electrostimulation treatment elicits transient but consistent penile erections in macaques. High rigidity following RES treatment demonstrates increased blood flow and may provide a functional model for penile PK evaluations and possibly simian immunodeficiency virus (SIV) transmission under erect conditions.
authors.affiliation: Animal Resources Branch, Division of Scientific Resources, National Center for Emerging Zoonotic and Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: James
authors.initials: J
authors.lastname: Hayes
authors.affiliation: Animal Resources Branch, Division of Scientific Resources, National Center for Emerging Zoonotic and Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Powell
authors.affiliation: Animal Resources Branch, Division of Scientific Resources, National Center for Emerging Zoonotic and Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: George
authors.initials: G
authors.lastname: Lathrop
authors.affiliation: Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Walid
authors.initials: W
authors.lastname: Heneine
authors.affiliation: Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Dobard
mesh_terms: D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D044966:Anti-Retroviral Agents / Q000493:pharmacokinetics*; D004195:Disease Models, Animal; D004558:Electric Stimulation; D008253:Macaca mulatta / Q000378:metabolism / Q000502:physiology*; D008297:Male; D010409:Penile Diseases / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D010410:Penile Erection / Q000502:physiology*; D010413:Penis / Q000098:blood supply / Q000187:drug effects / Q000502:physiology; D000068677:Sildenafil Citrate / Q000494:pharmacology; D016097:Simian Acquired Immunodeficiency Syndrome / Q000378:metabolism* / Q000503:physiopathology; D014665:Vasodilator Agents / Q000494:pharmacology; D014732:Vibration
chemical_list: D044966:Anti-Retroviral Agents; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; D000527:Alprostadil
keywords: Alprostadil; microbicides; penile vibratory stimulation; rectal electrostimulation; sildenafil citrate