Objective: To compare the frequency of apoptosis in the erectile tissue of chronic diabetic and healthy rats.
Materials and methods: Fourteen chronic diabetic and 10 healthy Sprague-Dawley rats were killed, their penises harvested and stored at -70 degrees C until staining and flow cytometric analysis for apoptosis. A cell suspension was obtained from the penile tissue by scraping the inside of the cavernosum with a scalpel and filtering through a mesh. Samples of the cell suspension (0.5 x 106 cells) were stained with Annexin V (an indicator of apoptosis) and propidium iodide (PI, which stains dead cells), incubated for 15 min at room temperature and analysed by flow cytometry. The DNA content was also analysed in each sample.
Results: In normal erectile tissue, a mean of 6.2% of cells were stained with Annexin V, while only 2.7% were stained with PI; DNA content analyses showed 7.5% were hypodiploid cells. In diabetic rats 19.5% of cells were stained with Annexin V and 5.2% with PI; 22.9% of cells were hypodiploid.
Conclusion: The ratio of apoptotic cells in the erectile tissues of diabetic rats was significantly greater than in normal rats. The high rate of apoptosis in diabetic rats may play a role in the pathophysiology of erectile dysfunction.