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Urol Ann. 2014 Oct;6(4):314-20. doi: 10.4103/0974-7796.140993.

The effects of combined free radical scavenger and sildenafil therapy on age-associated erectile dysfunction: An animal model.

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Urology of Indiana, 12188-A North Meridian Street, Suite 200, Carmel, Indiana, 46032, USA.
Department of Urology, University of Western Ontario, St. Joseph's Hospital, London, Ontario, N6A 4V2, Canada.
Dalhousie University, Halifax, Nova Scotia, Canada, McMaster University, Hamilton, Ontario, Australia.
Department of Urology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.



Aging results in erectile dysfunction that is partially attributed to decreased nitric oxide (NO) and increased free radical generation. Vitamin E enhances endothelial cell function and acts as a free radical scavenger; however, its benefits on erectile function in the elderly are unknown.


The aim of the following study is to determine if Vitamin E alone, or in combination with the phosphodiesterase 5 inhibitor sildenafil, may improve erectile function and the NO signaling in a cohort of aged (13-15 month old) rats.


Male Sprague-Dawley rats (n = 28) were divided based upon age into young (4-5 months old, n = 7) and aged (13-15 months old, n = 21) cohorts. Aged rats were treated with Vitamin E, sildenafil or a combination of both. Penile cavernosal and dorsal nerve tissues were evaluated for neuronal nitric oxide synthase (nNOS) and caveolin-1 expression. Erectile function was assessed through intra-cavernous pressure (ICP) recordings.


nNOS and cavoelin-1 were significantly decreased in aged rats compared with young controls. In aged rats, both Vitamin E and sildenafil partially recovered nNOS expression but when combined, a synergistic elevation in nNOS was observed. The significant decreases in ICP recorded in aged rats were improved with sildenafil; however, Vitamin E did not yield any additional improvements in ICP.


Diminished levels of nNOS and caveolin-1 are found in aged rats. When combined with sildenafil, Vitamin E synergistically increased nNOS expression. Since biochemical gains were not realized physiologically, other contributing factors likely exist.


Aging; antioxidant; erectile dysfunction; impotence; nitric oxide; sildenafil; vitamin E

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