Superoxide anion production by NADPH oxidase plays a major role in erectile dysfunction in middle-aged rats: prevention by antioxidant therapy.
INTRODUCTION.: Prevalence of erectile dysfunction (ED) increases progressively with aging, but the ED pathophysiology at its early stages is still poorly investigated. AIM.: This study aimed to evaluate the functional and molecular alterations of erectile function at middle age, focusing on the contribution of oxidative stress in erectile tissue for the ED. METHODS.: Young (3.5-month) and middle-aged (10-month) male Wistar rats were used. Rat corpus cavernosum (RCC) was dissected free and mounted in 10-mL organ baths containing Krebs solution. Intracavernosal pressure (ICP) in anesthetized rats was evaluated. MAIN OUTCOME MEASURES.: Concentration-response curves to endothelium-dependent and endothelium-independent agents, as well as to electrical field stimulation (EFS), were obtained in RCC strips. Measurement of cyclic guanosine monophosphate (cGMP) and expressions of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS), gp91(phox) and superoxide dismutase-1 (SOD-1) expressions in RCC were evaluated. RESULTS.: ICP was significantly reduced in middle-aged compared with young rats. RCC relaxations to acetylcholine (10(-8) to 10(-2)  M), sodium nitroprusside (10(-8) to 10(-2)  M), sildenafil (10(-9) to 10(-5)  M), BAY 41-2272 (10(-9) to 10(-5)  M), and EFS (4-32 Hz) were decreased in middle-aged group, which were nearly normalized by apocynin (NADPH oxidase inhibitor; 10(-4)  M) or SOD (75 U/mL). Prolonged treatment with apocynin (85 mg/rat/day, 4 weeks) also restored the impaired relaxations in middle-aged rats. Relaxations to 8-bromoguanosine 3',5'-cyclic monophosphate sodium salt (8-Br-cGMP; 10(-8) to 3 × 10(-4)  M) remained unchanged between groups. Basal and stimulated cGMP production were lower in middle-aged group, an effect fully restored by apocynin and SOD. Protein expression of nNOS and phosphorylated eNOS (p-eNOS) (Ser-1177) reduced, whereas gp(91phox) mRNA expression increased in RCC from middle-aged rats. CONCLUSIONS.: ED in middle-aged rats is associated with decreased NO bioavailability in erectile tissue due to upregulation of NADPH oxidase subunit gp91(phox) and downregulation of nNOS/p-eNOS. Antioxidant therapies may be a good pharmacological approach to prevent ED at its early stages.
Department of Pharmacology, Faculty of Medical Sciences, University of Campinas, Campinas, SP, Brazil.
Fábio H
FH
Silva
Fabíola Z
FZ
Mónica
Fernando R
FR
Báu
Ana F
AF
Brugnerotto
Fernanda B M
FB
Priviero
Haroldo A
HA
Toque
Edson
E
Antunes
D000098:Acetophenones / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000375:Aging / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D015536:Down-Regulation; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007172:Erectile Dysfunction / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009126:Muscle Relaxation; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D010410:Penile Erection; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism* / Q000494:pharmacology; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation; D014665:Vasodilator Agents / Q000494:pharmacology
C423582:3-(4-Amino-5-cyclopropylpyrimidine-2-yl)-1-(2-fluorobenzyl)-1H-pyrazolo(3,4-b)pyridine; D000098:Acetophenones; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D008562:Membrane Glycoproteins; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D011720:Pyrazoles; D011725:Pyridines; D012333:RNA, Messenger; D013450:Sulfones; D014665:Vasodilator Agents; D009599:Nitroprusside; C016276:8-bromocyclic GMP; C056165:acetovanillone; D000068677:Sildenafil Citrate; D019001:Nitric Oxide Synthase; C000606292:Sod1 protein, rat; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D006152:Cyclic GMP; D000109:Acetylcholine