Caloric restriction prevents visceral adipose tissue accumulation and maintains erectile function in aging rats

Abstract

Introduction: Increased adiposity is an important risk factor for erectile dysfunction (ED) and cardiovascular disease (CVD). Although accumulation of visceral adipose tissue (VAT) is recognized as a key mediator in the pathogenesis of CVD, its role in ED has not been elucidated.

Aim: To determine whether caloric restriction (CR) could prevent VAT accumulation and thereby prevent the onset of ED in normotensive rats.

Methods: Male Sprague Dawley rats (10 weeks) were randomized into three dietary groups: ad libitum control (CON), mild CR (CR(MI)), and moderate CR (CR(MOD)). Body weight (BW), body length abdominal girth (AG), and VAT (g-magnetic resonance imaging based) were assessed longitudinally. Erections were assessed using the apomorphine bioassay (80 µg/kg, SQ) after 20 weeks of CR. Excised VAT (mesenteric, epididymal, omental, and retroperitoneal), the internal pudendal artery (IPA) and serum were collected postmortem. Structure and function of the IPA was assessed at study end.

Main outcome measures: Erectile responses, adiposity (VAT), abdominal girth, serum analysis.

Results: BW (CON = 653 ± 58.6 g; CR(MI) = 535 ± 47.4 g; CR(MOD) = 409 ± 17.4 g) and VAT (CON = 39 ± 9.0 g; CR(MI) = 30 ± 9.9 g; CR(MOD) = 14 ± 3.5 g) were markedly different between the three groups. AG significantly correlated with longitudinal changes in VAT (R(2) = 0.61) and excised VAT (R(2) = 0.87). CR preserved erectile responses (CON = 0.6 ± 0.45, CR(MI) = 1.2 ± 0.77 g, CR(MOD) = 2.5 ± 0.43 g). A strong inverse correlation between VAT (%) and erectile function was found (R(2) = 0.74) whereas BW was less predictive of ED (R(2) = 0.48). There were no changes in traditional biomarkers (glucose, lipids) which could account for the ED. IPA structure was not different between groups, while CR(MOD) preserved endothelial function.

Conclusions: CR effectively prevented VAT accumulation in normotensive rats. Independently of changes in other metabolic markers, this intervention ameliorated the negative impact on erectile responses that occurs with age. Functional changes of the IPA may be a key mechanism by which erections are preserved with CR. AG was shown to be a strong index of VAT in rats.