The behavioral response induced by intravesical instillation of capsaicin in rats is mediated by pudendal urethral sensory fibers

Alessandro Lecci, Sandro Giuliani, Massimo Lazzeri, Giorgio Benaim, Damiano Turini, Carlo Alberto Maggi

Research output: Contribution to journalArticle

Abstract

The behavioral response induced by the intravesical instillation of capsaicin has been investigated in catheter-implanted, freely moving, conscious male and female rats. Intravesical instillation of capsaicin (25 nmol/rat in 0.5 ml) evoked an intense licking directed toward the lower abdominal and perineal skin which lasted for 15 min. Capsaicin-induced licking was reduced by systemic capsaicin pretreatment at a dose of 150 mg/kg but not at 50 mg/kg, administered 4 days before the intravesical instillation. Both doses of capsaicin effectively abolished the eye-wiping response to local capsaicin application. The capsaicin-induced licking was preserved (and prolonged) in both male and female animals subjected to bilateral ablation of the pelvic ganglia, 48 h before the intravesical instillation of the irritant. The capsaicin-induced licking was almost abolished by placing a ligature around the proximal urethra (24 h before), in order to avoid the contact of the irritant with the urethra or by previous section of the pudendal nerves (48 h before). One hour intravesical infusion with tetrodotoxin (1 and 10 μM) reduced the amplitude of micturition contractions but did not prevent the licking response evoked by capsaicin. On the contrary, the intravesical infusion of lidocaine (100 mM) abolished both micturition contractions and the capsaicin-induced licking. We conclude that the behavioral response induced by the intravesical instillation of capsaicin is mainly due to the stimulation of urethral afferents travelling within pudendal nerves.

Original languageEnglish
Pages (from-to)429-436
Number of pages8
JournalLife Sciences
Volume55
Issue number6
DOIs
Publication statusPublished - 1994

Keywords

  • capsaicin
  • micturition reflex
  • pelvic ganglia
  • pudendal nerves
  • tetrodotoxin
  • urethra
  • urinary bladder

ASJC Scopus subject areas

  • Pharmacology

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