Study question

This study was performed to evaluate the effects of myoinositol (MI) on sperm motility and clinical outcomes of IUI cycles.

Summary answer

Myoinositol improved the sperm motility and pregnancy rate of IUI cycles in asthenozoospermic patients, but it didn’t show any beneficial effect in normozoospermic patients.

What is known already

Percentage of spermatozoa with high mitochondrial membrane potential (MMP) levels showed a correlation with high fertilization rate because the MMP level of sperm is directly associated with motility of sperm. However the MMP level is inversely correlated with ROS level that induce a damage to the mitochondrial membrane. MI increased the percentage of spermatozoa with high MMP level in the patients with abnormal sperm parameters. Moreover, MI increased fertilization and pregnancy rates in women who failed to pregnancy due to poor oocyte quality by reducing oxidative stress in culture conditions.

Study design, size, duration

A prospective study was carried out to investigate the effects of MI on sperm motility and clinical outcomes in IUI cycles from August to December 2015. Total 376 patients (IUI cycles) were divided into two groups according to the addition of MI into sperm preparation medium; MI group (n=144) and Control group (n=232). Both groups were subdivided into 3 groups according to the result of semen analysis; Normozoo-, Asthenozoo-, and Oligoasthenozoo-spermic patient groups.

Participants/materials, setting, methods

Raw semen was treated with density gradient centrifugation for isolation of motile sperm, and then the motile sperm was washed twice with Ham’s F-10 with or without 5mg/ml MI. An antioxidant effect of MI on the sperm motility suppressed by hydrogen peroxide was investigated to identify the enhancing effect of MI on motility.

Main results and the role of chance

The effects of various MI concentrations (0, 2, 5, 10, 20 mg/ml) on motility of raw semen was investigated. Even the treatment with low concentration of 5mg/ml significantly increased the motility (38.1%) compared to the treatment without MI (21.5%, P<0.01). Unlike the raw semen, however, in the motile sperm isolated by density gradient centrifugation, the sperm motility in the MI group was not different from the motility in the control group (87.1% vs 83.5%). Between the MI and Control groups, there were no differences in the age of patients (female; 33.7 vs. 34.1, male; 35.9 vs.35.9), volume (3.4 vs. 3.3ml), count (89.5 vs. 101.8x106/ml), and motility (42.1 vs. 47.3%) of the raw semen. The pregnancy rates of asthenozoo- (28.8%) and oligoasthenozoo-spermic patients (33.3%) in the MI group were higher than those of control group (18.8 and 25.0%, respectively), although a statistical significance was not observed in the difference. Addition of hydrogen peroxide significantly decreased the sperm motility in a concentration-dependent manner. The suppressive effect of hydrogen peroxide was significantly reversed by addition of MI.

Limitations, reason for caution

The limitations of the present study included the limited number of samples tested, which slightly reduced the study’s statistical power.

Wider implications of the findings

MI improved sperm motility and pregnancy rate of IUI cycles in asthenozoospermic patients. The beneficial effect of MI may be associated with antioxidant activity as well as improvement of MMP level. Therefore, MI also may be useful for IVF-ET cycles in asthenozoospermic patients.