The ageing penis

Epidemiological reports have demonstrated the determinant role that age plays in the pathophysiological mechanism of an erection. The atherosclerosis of the penis and its ischaemia that occurs with ageing impacts directly on the intracavernous structures and the erectile physiologic function. The effects of testosterone on libido and sexual behaviour are well established but its function in the erectile mechanism remains unclear. In the animals, testosterone deficiency seems to provoke a decrease in smooth muscle content and nitric oxide (NO) production. In human, testosterone seems to affect the central system rather than the peripheral mechanism of an erection. The role of ischaemia and the decrease in testosterone in the mechanism of erectile dysfunction are reviewed.