title: Ex vivo relaxation effect of Cuscuta chinensis extract on rabbit corpus cavernosum.
abstract: The effect of Cuscuta chinensis extract on the rabbit penile corpus cavernosum (PCC) was evaluated in the present study. Penises obtained from healthy male New Zealand white rabbits (2.5-3.0 kg) were precontracted with phenylephrine (Phe, 10 µmol l(-1)) and then treated with various concentrations of Cuscuta chinensis extract (1, 2, 3, 4 and 5 mg ml(-1)). The change in penile tension was recorded, and cyclic nucleotides in the PCC were measured by radioimmunoassay (RIA). The interaction between Cuscuta chinensis and sildenafil was also evaluated. The result indicated that the PCC relaxation induced by Cuscuta chinensis extract was concentration-dependent. Pre-treatment with an nitric oxide synthase (NOS) inhibitor (Nω nitro-L-arginine-methyl ester, L-NAME), a guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ), or a protein kinase A inhibitor (KT 5720) did not completely inhibit the relaxation. Incubation of penile cavernous tissue with the Cuscuta chinensis extract significantly increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in the PCC. Moreover, the Cuscuta chinensis extract significantly enhanced sildenafil-induced PCC relaxation. In conclusion, the Cuscuta chinensis extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP pathway, and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.
authors.affiliation: Department of Urology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, and Shanghai Institute of Andrology, Shanghai 200127, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Chen
authors.initials: C
authors.lastname: Zhao
authors.forename: Xiang-Feng
authors.initials: XF
authors.lastname: Chen
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Bo-Ram
authors.initials: BR
authors.lastname: Choi
authors.forename: Yi-Ran
authors.initials: YR
authors.lastname: Huang
authors.forename: Jong-Kwan
authors.initials: JK
authors.lastname: Park
mesh_terms: D000818:Animals; D034182:Cuscuta / Q000737:chemistry*; D006152:Cyclic GMP / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007172:Erectile Dysfunction / Q000188:drug therapy*; D041743:Herb-Drug Interactions; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects*; D010413:Penis / Q000187:drug effects* / Q000502:physiology*; D008517:Phytotherapy; D010879:Piperazines / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D011817:Rabbits; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D010879:Piperazines; D010936:Plant Extracts; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester