Penile alterations at early stage of type 1 diabetes in rats

OBJECTIVE: Diabetes affects the erectile function significantly. However, the penile alterations in the early stage of diabetes in experimental animal models have not been well studied. We examined the changes of the penis and its main erectile components in diabetic rats. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into 2 groups: streptozotocin (STZ)-induced diabetics and age-matched controls. Three or nine weeks after diabetes induction, the penis was removed for immunohistochemical staining of smooth muscle and neuronal nitric oxide synthase (nNOS) in midshaft penile tissues. The cross-sectional areas of the whole midshaft penis and the corpora cavernosa were quantified. The smooth muscle in the corpora cavernosa and nNOS in the dorsal nerves were quantified. RESULTS: The weight, but not the length, of the penis was lower in diabetics. The cross-sectional areas of the total midshaft penis and the corpora cavernosa were lower in diabetic rats compared with controls 9 weeks, but not 3 weeks after diabetes induction. The cross-sectional area of smooth muscle in the corpora cavernosa as percentage of the overall area of the corpora cavernosa was lower in diabetic rats than in controls 9 weeks, but not 3 weeks after diabetes induction. Percentage change of nNOS in dorsal nerves was similar at 3 weeks, and has a decreased trend at 9 weeks in diabetic rats compared with controls. CONCLUSIONS: Diabetes causes temporal alterations in the penis, and the significant changes in STZ rat model begin 3-9 weeks after induction. Further studies on the reversibility of the observed changes are warranted.