Investigative Models in Erectile Dysfunction: A State-of-the-Art Review of Current Animal Models

Introduction. Erectile dysfunction (ED) is a common male sexual disorder producing a significant negative impact on the physical and psychosocial health of men and their partners. The development of ED is frequently attributable to both psychogenic factors as well as physiological alterations in neural, vascular, hormonal, and endothelial function. While the complex nature of human sexual function cannot possibly be replicated fully, the use of animal models provides a valid alternative to the investigation and evaluation of sexual dysfunction. Aim. To review the existing English literature pertaining to the use of experimental models (predominantly rodent models) for the evaluation of ED. Main Outcome Measures. Summary of relevant animal models of ED and the advantages and disadvantages of each animal model. Methods. A Medline search using the key words "animal models of erectile dysfunction" was carried out and all relevant peer-reviewed English language was evaluated. Results. While larger animals such as dogs, monkeys, cats, and rabbits were used in the early period of investigation (1960-1990), in recent times, rodents have largely replaced other animals as the predominant animal model for investigating erectile function. The most frequently reported models of ED can be classified as traumatic (cavernous nerve injury and arterial ligation) and metabolic (diabetic, hypercholesterolemia/lipidemia, and castration). Other models that have been studied include organic (smoking, hypertension, and chronic renal failure) and nonorganic (psychological) models. Conclusions. The development and utilization of the various rodent models has allowed for significant advances in the field of sexual dysfunction. Neurophysiological studies using the various animal models have provided important insights into human sexual dysfunction. At present, animal models play a significant role in evaluating novel therapeutics and surgical techniques and will likely continue to remain a vital research tool in the future