Acute effects of hypercholesterolemic diet on erectile responses in rats.

OBJECTIVE: The aim of this study was to evaluate the acute effects of a high cholesterol diet (HCD) on erectile and endothelial functions in Sprague-Dawley rats. MATERIALS AND METHODS: Sprague-Dawley rats were divided into 2 groups as control and HCD groups. The control group was fed on a normal diet and the hypercholesterolemia group was fed a 1% cholesterol-enriched diet daily for 2 weeks. Total cholesterol levels were measured at the end of 2 weeks in both groups. To examine the effect of HCD on erectile function, electric cavernous nerve stimulation (CNS) at 20 Hz with a pulse duration of 1 ms for 1 min at 5 V was performed. During CNS, we measured intracavernous pressure (ICP), mean arterial pressure (MAP), detumescence time and area under the curve (AUC). To evaluate the endothelial responses, acetylcholine (Ach) was applied cumulatively (1 nM to 1 microM) to thoracic aorta tissues contracted with 60 mM KCl. RESULTS: In the HCD group total cholesterol levels were significantly higher than in the control group (148.1 +/- 18.9 vs. 55.7 +/- 8.1 mg/dl, p = 0.002). The detumescence time was significantly decreased after HCD compared to the control diet (19.3 +/- 3.6 vs. 78.6 +/- 12.8 s, p < 0.001). The decreases in the HCD group were also significant in terms of ICP (53.4 +/- 4.5 vs. 35.6 +/- 5.5 mm Hg; p < 0.05), ICP/MAP (55.9 +/- 3.9 vs. 38.2 +/- 5.2%; p < 0.05) and AUC (1,404 +/- 197.1 vs. 2,250 +/- 253.7, p < 0.05) values. There were no significant changes in maximum relaxation responses of the thoracic aorta to Ach. CONCLUSION: These results suggest that erectile functions were significantly damaged early in HCD rats. However, endothelial functions, evaluated in the thoracic aorta, were not affected simultaneously with erectile functions in rats fed a low concentration of HCD.

Restraint stress impairs erectile responses in rats.

It has been established that various forms of physical and psychological stress reduce sexual functions. However, there is no study yet evaluating the functional changes over cavernosal pressure in rats exposed to restraint stress. In this study, we aimed to investigate the convenience of the restraint stress model that may be used to determine the disruptive effects of stress on erectile function. Sprague Dawley rats were randomized into two groups as control (n = 7) and stress (n = 7) groups. In the stress group, rats were placed for 60 minutes in a cylindrical plastic tube with holes for fresh air supply (restraint stress). Following the stress application, several parameters for erectile responses were evaluated immediately. The control animals were maintained at room temperature without any procedure until the measurement. During the electrical stimulation of cavernous nerve, we measured the intracavernous pressure (ICP), the ratio of ICP to the mean arterial pressure (MAP), and detumescence time. There were significant decreases in ICP (24.4 +/- 4.1 vs 53.4 +/- 4.5 mmHg, p < 0.01), ICP/MAP (34.4 +/- 7.8% vs 55.7 +/- 3.9%, p < 0.05), and detumescence time (31.7 +/- 6.1 vs 78.6 +/- 12.8 sec, p < 0.01) in stress group when compared to control group. Thus, restraint stress declined detumescence time and decreased intracavernosal pressure in male rats. In conclusion, restraint stress model in rats may be useful for determining the effects of stress on erectile response. Even a short-term restraint stress may cause erectile dysfunction.