Energy restriction, exercise and atorvastatin treatment improve endothelial dysfunction and inhibit miRNA-155 in the erectile tissue of the aged rat.

BACKGROUND: Endothelial dysfunction underlies cardiovascular disease that frequently affects aged individuals. Characterized by local decrease in nitric oxide, it results from down-regulation of endothelial nitric oxide synthase (eNOS) expression/activity. Aiming to elucidate the molecular mechanisms involved in age-related endothelial dysfunction and to unveil potential therapeutic targets, we tested how diet pattern, exercise and atorvastatin modulate the expression of eNOS, inducible NOS (iNOS), endothelin-1, sirtuins (SIRT) and microRNA-155 in the erectile tissue of high-fat fed aged rats. METHODS: Sprague-Dawley male rats fed with high-fat diet until they completed 12 months were grouped and subjected to energy restriction (ER), ER and atorvastatin, or, ER, atorvastatin and physical exercise. Controls were fed with standard rodent chow. The blood pressure was measured using the tail-cuff method before sacrifice at 18 months. Glucose, total cholesterol, HDL, triglyceride and CRP were assessed in blood and eNOS, endothelin-1, iNOS and sirtuins were detected by immunofluorescence in the penis sections; eNOS, endothelin-1, iNOS, SIRT2-4 and SIRT6-7 were semi-quantified by western blotting in tissue homogenates. MicroRNA-155 was quantified using RT-PCR in formalin-fixed paraffin embedded sections. To compare the studied variables, two-tail student t test was used. RESULTS: Atorvastatin promotes eNOS expression and is more efficient than ER or exercise in the control of hyperlipidemia and inflammation. Among the studied sirtuins, detected for the first time in the erectile tissue of the aged rat, SIRT2 aligns with eNOS expression. Both proteins exhibit over-expression in animals with combined exercise, atorvastatin and ER. Analysis of microRNA-155 expression also suggests its intervention in the regulation of eNOS expression. ER, particularly when combined with atorvastatin, was able to reverse the increase of iNOS and endothelin-1 in high-fat fed rats. CONCLUSIONS: The present results indicate that the association of ER, atorvastatin and exercise is more efficient than isolated interventions in the prevention of endothelial dysfunction.

Long-term high-fat consumption leads to downregulation of Akt phosphorylation of eNOS at Ser1177 and upregulation of Sirtuin-1 expression in rat cavernous tissue.

Long-term consumption of high-fat diets negatively interferes with metabolic status and promotes endothelial dysfunction and inflammation. In the cavernous tissue, these outcomes become conspicuous in the elderly and strongly affect penile erection, a vascular process highly dependent on local nitric oxide bioavailability. Although epidemiological data links erectile dysfunction to nutritional patterns, the underlying molecular mechanisms remain unclear. Therefore, we investigated the effects of long-term high-fat diet on endothelial nitric oxide synthase (eNOS)-Sirtuin-1 axis and Akt/eNOS phosphorylation in the cavernous tissue of Sprague-Dawley rats, and compared with energy-restricted animals. We demonstrated that high-fat diet intake led to a noteworthy decrease in eNOS phosphorylation at Ser1177 residue through the Akt pathway, which seems to be compensated by upregulation of phosphorylation at Ser615, but without an increment in nitric oxide production. These results are accompanied by an increase of systemic inflammatory markers and upregulation of the inducible NOS and of the deacetylase Sirtuin-1 in the cavernous tissue to levels apparently detrimental to cells and to metabolic homeostasis. Conversely, in long-term energy-restricted animals, the rate of phosphorylation of eNOS at Ser1177 diminished, but the activation of the enzyme increased through phosphorylation of eNOS at Ser615, resulting in an enhancement in nitric oxide bioavailability. Taken together, our results demonstrate that long-term nutritional conditions override the influence of age on the eNOS expression and activation in rat cavernous tissue.

Endothelial function in patients with metabolic syndrome and erectile dysfunction: a question of angiopoietin imbalance?

Erectile dysfunction (ED) is a highly prevalent disease whose aetiology is mostly vasculogenic. It is nowadays considered a marker of future cardiovascular events reflecting the underlying endothelial dysfunction, the common link with the metabolic syndrome (MetS). The recent association between MetS, endothelial dysfunction and peripheral artery disease, but not with coronary artery disease (CAD), suggests that the pathophysiologies of CAD and peripheral artery disease may be distinct. Moreover, several recent studies support an emerging role for an imbalance of angiogenic growth factor levels like Angiopoietin 1 and 2 in cardiovascular disease, considering its intimate association with chronic low-grade inflammation. We aim to find a correlation between Angiopoietins levels and systemic and local endothelial function in MetS and ED patients. Forty-five MetS patients with ED were enrolled. ED severity was assessed by International Index of Erectile Function questionnaire (IIEF5) and penile duplex Doppler ultrasound (PDDU). Endothelial function was assessed by Peripheral arterial tonometry (PAT), and serum asymmetric dimethylarginine (ADMA), Ang1 and Ang2 levels. Obesity and hypertension were the most frequent MetS parameters (91.1 and 88.9% respectively). Severe ED was present in 35.6% of patients. Penile haemodynamic was impaired in 77.5%. Endothelial dysfunction (PAT criteria) was present in 40.9% of patients. Ang2 levels were significantly higher in men with abdominal obesity. We observed an inverse correlation between Ang1 and peak systolic velocity, and in patients with penile arterial dysfunction, Ang1 levels were significantly higher and Ang2/Ang1 ratio significantly lower, than patients with normal arterial function. Neither ADMA nor PAT parameters were correlated with ED severity evaluated by IIEF5 or PDDU exam. In conclusion, there is an imbalance of angiopoietins in MetS and ED patients. The absence of correlation with PAT or ADMA levels suggests that angiopoietins may be early markers of endothelial dysfunction in this population of higher cardiovascular risk.