Tideglusib, a prospective alternative to nonoxynol-9 contraceptive

Sperm Toolbox-A selection of small molecules to study human spermatozoa

Male contraceptive options and infertility treatments are limited, and almost all innovation has been limited to updates to medically assisted reproduction protocols and methods. To accelerate the development of drugs that can either improve or inhibit fertility, we established a small molecule library as a toolbox for assay development and screening campaigns using human spermatozoa. We have profiled all compounds in the Sperm Toolbox in several automated high-throughput assays that measure stimulation or inhibition of sperm motility or the acrosome reaction. We have assayed motility under non-capacitating and capacitating conditions to distinguish between pathways operating under these different physiological states. We also assayed cell viability to ensure any effects on sperm function are specific. A key advantage of our studies is that all compounds are assayed together in the same experimental conditions, which allows quantitative comparisons of their effects in complementary functional assays. We have combined the resulting datasets to generate fingerprints of the Sperm Toolbox compounds on sperm function. The data are included in an on-line R-based app for convenient querying.

Role of the Glycogen Synthase Kinase 3-Cyclic AMP/Protein Kinase A in the Immobilization of Human Sperm by Tideglusib

Tideglusib is considered to be a promising alternative to nonyl alcohol-9 contraceptives. Previous studies have demonstrated that the rapid spermicidal effect of tideglusib at a high concentration (≥ 10 μM) may occur through detergent-like activity; however, the effect of low concentrations of tideglusib (< 5 μM) on sperm is unknown. We explored the intracellular mechanism of tideglusib (< 5 μM) on the immobilization of human sperm by exploring related signaling pathways in human sperm. After treatment with tideglusib (1.25 μM) for 2 h, sperm motility rate decreased to 0, while sperm membrane integrity rate was 70%. Protein tyrosine phosphorylation level and intracellular cyclic adenosine 3,5-monophosphate (cAMP) concentration decreased significantly compared to those in the control group. Isobutylmethylxanthine and 8-Bromo-cAMP relieved the inhibition of spermatozoa tyrosine phosphorylation, while tyrosine phosphorylation of sperm protein in the H89 and CALP1 treatment groups was significantly inhibited, and there was no difference in the tideglusib treatment group. H-89 and CALP1 reduced the level of serine phosphorylation of GSK-3α/β (Ser21/9), while its level was enhanced by IBMX and 8-Bromo-cAMP. Our results show the existence of the GSK3-cAMP/PKA regulatory loop in human sperm, which may mediate the immobilization effect of tideglusib at low of concentrations (e.g., 1.25 μM) on sperm motility.

Effects of nonoxynol-9 (N-9) on sperm functions: systematic review and meta-analysis

Objective

To summarize the currently available phase I and II clinical trials of the effects of nonoxynol-9 (N-9) on human sperm structure and functions.

Methods

A systematic review and meta-analysis aiming to evaluate the spermicidal activity of N-9 on motility, was conducted in PubMed, EMBASE, and Cochrane databases by 10 March 2021. The counted numbers of progressive motile (PR) sperm in cervical mucus and the vanguard sperm penetration distances were analyzed. Other effects on sperm structures and physiological activities were reviewed as well.

Results

In the pooled results, percentages or counted numbers of PR sperm decreased after the treatment of N-9. Vanguard sperm penetration distance was shortened in treated groups. N-9 has been confirmed to damage the structures of sperm, as well as other organelles like acrosome and mitochondria. The physiological activities such as generation of reactive oxygen species, superoxide dismutase activity, acrosin activity, and hemizona binding were all inhibited in the reviewed studies.

Conclusions

N-9 has several impacts on sperm owing to its potency in reducing sperm motility and cervical mucus penetration, as well as other functional competencies.

Lay summary

Nonoxynol-9 (N-9) has been used worldwide as a spermicide to kill sperm for more than 60 years but can cause side effects including vaginal irritation and can increase the rate of contraceptive failure. A detailed analysis of published literature aiming to evaluate the spermicidal activity of N-9 on sperm was carried out. In the pooled results, N-9 reduced the number of active sperm and the distance they traveled. It also caused damage to the structures of sperm and to the way the sperm acted and interacted with the egg. In conclusion, N-9 impacts on sperm in a number of ways that lead to sperm death and dysfunction.