Effect of phosphodiesterase type 5 inhibitors on sperm motility and acrosome reaction: An in vitro study

Abstract

Purpose: Phosphodiesterase type 5 (PDE5) inhibitors are effective treatments for erectile dysfunction, and several recent studies have reported positive effects of PDE5 inhibitors on semen parameters as well. However, the data are still controversial. We investigated the effect of PDE5 inhibitors on sperm function by analyzing sperm motility and acrosome reaction.

Materials and methods: This study included young healthy men who underwent fertility evaluation; 32 cases were finally included. Men were excluded if they used a PDE5 inhibitor within 2 weeks or if they had insufficient semen volume (≤2 mL), leukocytospermia, or a genitourinary infection. Changes in sperm motility and acrosome reaction were determined after in vitro exposure to the maximal semen concentration of oral intake of sildenafil (100 mg) or tadalafil (20 mg).

Results: Mean age of the participants was 35.4±4.9 years, mean sperm concentration was 68.7±32.4 ×10⁶/mL, and mean sperm motility was 50.38%±8.41%. All three groups (control, sildenafil, tadalafil) experienced trends of decreased average sperm motility over time, but these changes were not significant. There were no significant differences between the three groups in the acrosome reaction after 120 minutes of drug exposure, either. The maximal semen concentration of oral intake of sildenafil (100 mg) or tadalafil (20 mg) did not substantially affect sperm motility or acrosome reaction.

Conclusions: Our results suggest that on-demand use of a PDE5 inhibitor is safe and useful for the male partner of an infertile couple; however, further studies are warranted for daily PDE5 inhibitor use.

Keywords: Erectile dysfunction; Infertility; Phosphodiesterase type 5 inhibitor; Spermatozoa.

Fig. 1. (A) DAPI- and PNA-labeled sperm images and merged images of DAPI and PNA staining (×1,000). (B) All sperm were stained with DAPI for the nucleus and PNA for the acrosome. (C) Stained sperms were divided into the following groups according to the degree of PNA staining: (a) intact acrosome, (b) partially reacted acrosome, and (c) reacted acrosome.

Fig. 2. Evaluation of sperm motility with time. The decline in sperm motility appeared smaller in groups that received the phosphodiesterase type 5 (PDE5) inhibitor than in the control group, but a repeatedmeasures ANOVA indicated no significant differences (p=0.312).

Fig. 3. Comparison of sperm acrosome reaction status. Sperm acrosome reaction status after 2 hours of exposure to the maximal semen concentration of sildenafil and tadalafil solution did not differ significantly between the groups.