Erectile dysfunction: etiology, evaluation, and treatment options

Effects of sexual arousal on vibrotactile detection thresholds in aged men with and without erectile dysfunction

BACKGROUND

Erectile dysfunction (ED) is a common problem in ageing men. Abnormalities in sexual arousal may contribute to its development, and to the failure of pharmacological therapies. However, there are few objective ways of assessing arousal. Sexual arousal has been shown to affect vibrotactile detection thresholds (VDT) in young, healthy men. The present study assessed the effects of sexual arousal on VDT in middle-aged men with and without ED in order to determine whether differences exist between the groups and if such differences may be useful in the evaluation of ED.

METHODS

VDT in the right index finger of 15 heterosexual men (mean age 74.3 +/- 6.0 years) who had been formally diagnosed with ED (ED group) and 16 men (mean age 68.0 +/- 6.6 years) who reported no sexual dysfunction in the past 6 months (erectile function (EF) group) were measured before and after watching erotic and control videos using a forced-choice, staircase method at frequencies of 30, 60 and 100 Hz. A mechanical stimulator was used to produce the vibratory stimulus. Results were analysed using repeated-measures analysis of variance.

RESULTS

There was no significant effect of watching the erotic video on VDT in subjects in the ED group. In the EF group, VDT was significantly lower at 60 and 100 Hz after watching the erotic video. There was no change in VDT after watching the control video in either group.

CONCLUSION

In response to sexual arousal, VDT in ageing men with normal erectile function decrease, whereas VDT in ageing men with ED remain unchanged.

Centrally acting mechanisms for the treatment of male sexual dysfunction

The development of pharmacologic therapy for erectile dysfunction (ED) has been possible because of incremental growth in our understanding of the physiology of normal erections and the complex pathophysiology of ED. Although the oral phosphodiesterase type 5 (PDE5) inhibitors have provided safe, effective treatment of ED for some men, a large proportion of men who have ED do not respond to PDE5 inhibitors or become less responsive or less satisfied as the duration of therapy increases. Also, men who are receiving organic nitrates and nitrates, such as amyl nitrate, cannot take PDE5 inhibitors because of nitrate interactions. The current options for treatment beyond PDE5 inhibitors are invasive, unappealing to some patients, and sometimes ineffective. The search for other options by which ED can be treated has branched out and now encompasses centrally acting mechanisms that control erectile function. Drugs available in Europe include apomorphine. This article focuses on the mechanism of centrally acting agents and reviews clinical data on potential new centrally acting drugs for men who have ED.

Corporal veno-occlusive dysfunction in aging rats: Evaluation by cavernosometry and cavernosography

OBJECTIVES

To determine whether the rat develops corporal veno-occlusive dysfunction (CVOD) during the aging process.

METHODS

We divided male Fisher 344 rats into four groups with 5 to 8 rats in each group. Group 1 rats were 5 months old and not orchiectomized (young intact); group 2 were 5 months old and had undergone castration (control CVOD); group 3 were 24 months old and not orchiectomized (aged intact); and group 4 rats were 24 months old, nonorchiectomized rats who had undergone deep dorsal vein (DDV) ligation (aged ligated). Serum testosterone was measured, and dynamic infusion cavernosometry and cavernosography (by dual-energy x-ray absorptiometry scan) were performed.

RESULTS

Compared with the young intact animals, the aged intact rats had a 73% reduction in testosterone, a 30% reduction in intracavernosal pressure after papaverine injection, and an 84% and a 44% increase in the maintenance and drop rate, respectively, during dynamic infusion cavernosometry. The extent of CVOD as measured by cavernosometry in the aged rats was similar to that in the young castrated rats, but was more pronounced when measured by dynamic infusion cavernosometry. Cavernosography confirmed that the aged rats had venous leakage primarily by way of the DDV. By applying DDV ligation, distal penile engorgement occurred, showing that a small venous leakage occurred primarily by way of the cavernosal veins.

CONCLUSIONS

These data have demonstrated that CVOD occurs in the aged rat, mainly through the DDV. This supports the concept that the aged rat is an appropriate animal model to study erectile dysfunction associated with CVOD.