The influence of smoking exposure and cessation on penile hemodynamics and corporal tissue in a rat model

Background: While epidemiological studies have clearly documented that smoking cessation significantly enhances sexual health, the underlying mechanism remains largely unknown. Thus, we wished to explore possible mechanisms by using a rat model of smoking-associated erectile dysfunction (ED). Methods: Forty 8-week old male Sprague-Dawley rats were divided into 4 groups. Ten rats were exposed only to room air (N group). The remaining 30 rats were passively exposed to cigarette smoke over a 12-week period. At the end of 12 weeks, the smoking (S, n=10) group underwent immediate erectile function testing and were sacrificed. The remaining 20 rats were exposed to room air only for 4 (Q4W, n=10) or 8 (Q8W, n=10) weeks and then underwent erectile function testing and sacrifice. Erectile function was evaluated by measuring intracavernous pressure (ICP) and mean arterial pressure (MAP). After blood collection for serum testosterone determination, rats were sacrificed to obtain corporal tissue for immunohistochemistry. Results: Mean ICP/MAP ratio was significantly lower in the S group compared to the N and Q8W groups (0.52±0.11, 0.94±0.05, and 0.94±0.12, respectively, P=0.0189). Smooth muscle/collagen ratio was also significantly lower in the S group compared to the N and Q8W groups (11.8±0.94, 17.5±1.82, and 16.4±0.60, respectively, P=0.0008). Oxidative stress and apoptotic indices were significantly higher in the S group compared to the N and Q8W groups. Neuronal and endothelial nitric oxide synthases were significantly less expressed in the S group compared to the N and Q8W groups. Conclusions: Smoking cessation is associated with partial recovery of penile hemodynamics in a rat model of smoking associated ED.