Sonic hedgehog protein is decreased and penile morphology is altered in prostatectomy and diabetic patients

Erectile dysfunction (ED) is a debilitating medical condition and current treatments are ineffective in patients with cavernous nerve (CN) injury, due to penile remodeling and apoptosis. A critical regulator of penile smooth muscle and apoptosis is the secreted protein sonic hedgehog (SHH). SHH protein is decreased in rat prostatectomy and diabetic ED models, SHH inhibition in the penis induces apoptosis and ED, and SHH treatment at the time of CN injury suppresses smooth muscle apoptosis and promotes regeneration of erectile function. Thus SHH treatment has significant translational potential as an ED therapy if similar mechanisms underlie ED development in patients. In this study we quantify SHH protein and morphological changes in corpora cavernosal tissue of control, prostatectomy and diabetic patients and hypothesize that decreased SHH protein is an underlying cause of ED development in prostatectomy and diabetic patients. Our results show significantly decreased SHH protein in prostatectomy and diabetic penis. Morphological remodelling of the penis, including significantly increased apoptotic index and decreased smooth muscle/collagen ratio, accompanies declining SHH. SHH signaling is active in human penis and is altered in a parallel manner to previous observations in the rat. These results suggest that SHH has significant potential to be developed as an ED therapy in prostatectomy and diabetic patients. The increased apoptotic index long after initial injury is suggestive of ongoing remodeling that may be clinically manipulatable.