title: Akt-dependent phosphorylation of endothelial nitric-oxide synthase mediates penile erection.
abstract: In the penis, nitric oxide (NO) can be formed by both neuronal NO synthase and endothelial NOS (eNOS). eNOS is activated by viscous drag/shear stress in blood vessels to produce NO continuously, a process mediated by the phosphatidylinositol 3-kinase (PI3kinase)/Akt pathway. Here we show that PI3-kinase/Akt physiologically mediates erection. Both electrical stimulation of the cavernous nerve and direct intracavernosal injection of the vasorelaxant drug papaverine cause rapid increases in phosphorylated (activated) Akt and eNOS. Phosphorylation is diminished by wortmannin and LY294002, inhibitors of PI3-kinase, the upstream activator of Akt. The two drugs also reduce erection. Penile erection elicited by papaverine is reduced profoundly in mice with targeted deletion of eNOS. Our findings support a model in which rapid, brief activation of neuronal NOS initiates the erectile process, whereas PI3-kinase/Akt-dependent phosphorylation and activation of eNOS leads to sustained NO production and maximal erection.
authors.affiliation: Department of Neuroscience, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
authors.forename: K Joseph
authors.initials: KJ
authors.lastname: Hurt
authors.forename: Biljana
authors.initials: B
authors.lastname: Musicki
authors.forename: Michael A
authors.initials: MA
authors.lastname: Palese
authors.forename: Julie K
authors.initials: JK
authors.lastname: Crone
authors.forename: Robyn E
authors.initials: RE
authors.lastname: Becker
authors.forename: John L
authors.initials: JL
authors.lastname: Moriarity
authors.forename: Solomon H
authors.initials: SH
authors.lastname: Snyder
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Burnett
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002867:Chromones / Q000494:pharmacology; D004558:Electric Stimulation; D004727:Endothelium / Q000187:drug effects / Q000201:enzymology / Q000294:innervation / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D008297:Male; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D010208:Papaverine / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects; D010413:Penis / Q000187:drug effects / Q000201:enzymology* / Q000294:innervation / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D009025:Morpholines; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D010208:Papaverine; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C496322:Nos1 protein, rat; C496316:Nos3 protein, rat; C494920:Akt1 protein, rat