Influence of physical training in the erectile function of chronic NO-defficient rats

Author(s)

Mário Angelo Claudino

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2008-06-20

Examining board members

Edson Antunes; Claudio Alexandre Gobatto; Licio Augusto Velloso; Tania Crisitna Pithon Curi; Maria Helena Catelli de Carvalho

• Advisor: Edson Antunes

Abstract

Erectile dysfunction is defined as the consistent or recurrent inability of a man to attain and/or maintain a penile erection sufficient for sexual activity, and can occur in different levels leading to an impairment of men¿s quality of life. Risk factors such as cardiovascular diseases, arterial hypertension, diabetes mellitus, hypercholesterolemia, aging, smoking and life sedentary increase the prevalence of erectile dysfunction. Nitric oxide (NO) is the main mediator of relaxation of penile smooth muscle. Clinical and experimental evidences suggest that decreased NO biodisponibility or NO reactivity contribute to erectile dysfunction. Recent studies have shown that part of beneficial effects of regular physical activity in the cardiovascular system is due to an increase in NO production and/or NOS expression by endothelial cells. Therefore, the aim of this work was to study the influence of run training on the erectile function from rats under chronic NO blockade by long-term treatment with L-NAME. First, we investigated the influence of physical training in the erectile function of healthy, normotense rats. Second, we studied the influence of prior physical conditioning in the erectile function of chronic NO-defficient rats. Third, we evaluated the therapeutic efficacy of regular physical activity (pós-conditioning) in the erectile function in chronic NO-defficient rats. To achieve this, we evaluated the functional responses (measurements of cavernosal relaxation in vitro and intracavernosal pressure in vivo) and the plasma levels of nitrite/nitrate (NOx) and plasmatic superoxide dismutase (SOD) activity, protein expression of neuronal NOS (nNOS), nitrotyrosin (3-NT) and SOD, and gene expression of gp91phox in the corpus cavernosum. In healthy normotenses rats, physical training by 8 weeks improved the relaxant responses mediated by NO (added as acidified sodium nitrite solution; NaNO2), sodium nitricprusside (SNP) and electrical field stimulation (EFS), without affecting the contractile responses induced by phenilephrine (PE) and endothelin (ET-1). In NO-defficient rats, the prior physical conditioning attenuated the increased arterial pressure, and potentiated the relaxations of corpus cavernosum induced by SNP, ACh and EFS. However, no changes were found for BAY 41-2271 and sildenafil. In NO-defficient animals, the physical activity normalized the intracavernosal pressure and plasma NOx levels. The post-conditioning (therapeutic efficacy) also attenuated the L-NAME induced arterial hypertension, potentiated the SNP-induced relaxations and reverted the reductions of relaxing responses to ACh and EFS. Furthermore, post-conditioning nomalized the intracavernosal pressure and attenuated the plasma NOx levels. Protein expression of nNOS and PnNOS were not affected by post physical activity. However, the increase of protein nitration (3-NT) was reversed by postconditioning in the NO-defficient animals. The protein expression of SOD was not modified by exercise. Nevertheless, the physical activity attenuated the reduction of SOD plasma activity. The gp91phox expression was decreased in NO-defficient rats, and restored by physical training. In conclusion, we conclude that physical training (pre or post-conditioning) is an efficient nos-pharmcological approach able to reduce the oxidative stress, increasing the NO bioavailability that results in an improvement of erectile dysfunction (AU)