title: Effects of castration on adrenergic, cholinergic and nonadrenergic, noncholinergic responses of isolated corpus cavernosum from rabbit.
abstract: OBJECTIVE
  To investigate the effects of castration and testosterone on the constricting effect of phenylephrine and endothelium-dependent and -independent relaxing effects of different agonists in the corpus cavernosum of male rabbits.
  
  
  METHODS
  Twenty rabbits were castrated and 10 received testosterone replacement for 1 month after castration; 10 further rabbits underwent a sham operation and acted as controls. One month after operation the rabbits were killed and their penises excised. Strips of corpus cavernosum were used for isometric tension measurements in organ chambers; concentration-response relationships for phenylephrine, carbachol, adenosine and sodium nitroprusside were obtained by adding the reagent cumulatively to the bath.
  
  
  RESULTS
  The phenylephrine-induced contractions were markedly lower, with no change in the pD2 values (i.e. the negative logarithm of the concentration for half-maximal response), in cavernosal strips obtained from castrated rabbits than in those from controls. Endothelium-dependent relaxation elicited by carbachol increased in the castrated group but the relaxation induced by sodium nitroprusside did not change and those elicited by adenosine were strongly depressed when compared with controls. There were no significant changes in the pD2 values of agonist-induced relaxation responses in all groups. The relaxation elicited by electrical-field stimulation at lower frequencies increased in strips from castrated rabbits but at higher frequencies were unchanged when compared with controls. Castration-induced changes in the relaxation response of cavernosal strips were significantly restored by in vivo testosterone replacement but those induced by phenylephrine were not.
  
  
  CONCLUSIONS
  The lack of testosterone has an effect on the reactivity of the corpus cavernosum, indicating that testosterone has an important role in erectile function by a pre- or post-synaptic action on the corpus cavernosum.
authors.affiliation: Cumhuriyet University, Faculty of Medicine, Department of Pharmacology, Sivas, Turkey.
authors.forename: M K
authors.initials: MK
authors.lastname: Yildirim
authors.forename: S
authors.initials: S
authors.lastname: Yildirim
authors.forename: T
authors.initials: T
authors.lastname: Utkan
authors.forename: Y
authors.initials: Y
authors.lastname: Sarioglu
authors.forename: Y
authors.initials: Y
authors.lastname: Yalman
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004558:Electric Stimulation; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009599:Nitroprusside / Q000494:pharmacology; D009919:Orchiectomy; D010277:Parasympathomimetics / Q000494:pharmacology; D010413:Penis / Q000378:metabolism / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D011817:Rabbits; D013739:Testosterone / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D010277:Parasympathomimetics; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D013739:Testosterone; D002217:Carbachol; D000241:Adenosine