title: Epimedium brevicornum Maxim extract relaxes rabbit corpus cavernosum through multitargets on nitric oxide/cyclic guanosine monophosphate signaling pathway.
abstract: Epimedium brevicornum Maxim (EbM) has been reputed to have sexual stimulation effects on males. The study is aimed to test the hypothesis that EbM extracts relaxed the corpus cavernosum (CC) smooth muscle through activation of multitargets on nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway. Water extract of EbM and its subfraction (EP-20) were prepared and standardized by high-performance liquid chromatography. Isolated rabbit CC strips were mounted in organ baths and isometric tension was recorded in the presence or absence of specific inhibitors related to NO/cGMP signaling such as L-N(G)-nitro-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ, a guanylyl cyclase inhibitor) or phosphodiesterase 5 (PDE 5) inhibitors. cGMP level was determined in EP-20-treated CC strips. The results showed that EP-20 enriched the content of L-arginine in the process of purification and relaxed the CC smooth muscle precontracted with phenylephrine (PE, 1 microM) in a concentration-dependent manner. Besides, EP-20 increased the amount of cGMP production in rabbit CC tissues. Coincubation with EP-20 and L-NAME or ODQ significantly decreased EP-20-induced relaxation whereas EP-20 increased sodium nitroprusside-induced relaxation in PE-precontracted CC strips. Besides, EP-20 increased the potency and the duration of the relaxation effects caused by electrical field stimulation. Finally, EP-20 could potentiate PDE 5 inhibitors in relaxation of PE-precontracted CC strips. We concluded that extract of EbM relax the CC smooth muscle through multitargets in NO/cGMP/PDE 5 pathway and might bring into perspective the treatment strategy for those patients with erectile dysfunction.
authors.affiliation: Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Peitou, Taipei, Taiwan, ROC. chiujh@mailsrv.ym.edu.tw
authors.forename: J-H
authors.initials: JH
authors.lastname: Chiu
authors.forename: K-K
authors.initials: KK
authors.lastname: Chen
authors.forename: T-M
authors.initials: TM
authors.lastname: Chien
authors.forename: W-F
authors.initials: WF
authors.lastname: Chiou
authors.forename: C-C
authors.initials: CC
authors.lastname: Chen
authors.forename: J-Y
authors.initials: JY
authors.lastname: Wang
authors.forename: W-Y
authors.initials: WY
authors.lastname: Lui
authors.forename: C-W
authors.initials: CW
authors.lastname: Wu
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases; D000818:Animals; D001120:Arginine / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D034181:Epimedium / Q000737:chemistry*; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology; D010413:Penis / Q000187:drug effects* / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D011817:Rabbits; D015398:Signal Transduction
chemical_list: D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D010936:Plant Extracts; D009599:Nitroprusside; D010656:Phenylephrine; D009569:Nitric Oxide; D001120:Arginine; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester