title: Activation of somatosensory afferents elicit changes in vaginal blood flow and the urethrogenital reflex via autonomic efferents.
abstract: OBJECTIVE
  We examined the effects of pudendal sensory nerve stimulation and urethral distention on vaginal blood flow and the urethrogenital reflex, and the relationship between somatic and autonomic pathways regulating sexual responses.
  
  
  METHODS
  Distention of the urethra and stimulation of the pudendal sensory nerve were used to evoke changes in vaginal blood flow (laser Doppler perfusion monitoring) and pudendal motor nerve activity in anesthetized, spinally transected female rats. Bilateral cuts of either the pelvic or hypogastric nerve or both autonomic nerves were made, and blood flow and pudendal nerve responses were reexamined.
  
  
  RESULTS
  Stimulation of the pudendal sensory nerve or urethral distention elicited consistent increases in vaginal blood flow and rhythmic firing of the pudendal motor nerve. Bilateral cuts of the pelvic plus hypogastric nerves significantly reduced vaginal blood flow responses without altering pudendal motor nerve responses. Pelvic nerve cuts also significantly reduced vaginal blood flow responses. In contrast, hypogastric nerve cuts did not significantly change vaginal blood flow. Bilateral cuts of the pudendal sensory nerve blocked pudendal motor nerve responses but stimulation of the central end evoked vaginal blood flow and pudendal motor nerve responses.
  
  
  CONCLUSIONS
  Stimulation of the sensory branch of the pudendal nerve elicits vasodilatation of the vagina. The likely mechanism is via activation of spinal pathways that in turn activate pelvic nerve efferents to produced changes in vaginal blood flow. Climatic-like responses (firing of the pudendal motor nerve) occur in response to stimulation of the pudendal sensory nerve and do not require intact pelvic or hypogastric nerves.
authors.affiliation: Division of Urology, Department of Surgery, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7052, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Cai
authors.forename: M Sipski
authors.initials: MS
authors.lastname: Alexander
authors.forename: L
authors.initials: L
authors.lastname: Marson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D019540:Area Under Curve; D017776:Autonomic Pathways / Q000502:physiology*; D001783:Blood Flow Velocity; D004558:Electric Stimulation; D005260:Female; D007001:Hypogastric Plexus / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology*; D014521:Urethra / Q000098:blood supply / Q000294:innervation; D014621:Vagina / Q000098:blood supply* / Q000294:innervation*