Hiding in Plain Sight: Nebivolol Exhibits Compelling Tocolytic Properties

Area of Science:

• Reproductive Biology
• Pharmacology
• Biochemistry

Background:

• Preterm birth before 37 weeks poses significant fetal health risks.
• Preterm labor causes over 50% of preterm births, with no FDA-approved preventative treatments.
• Protein S-nitrosation in uterine smooth muscle is crucial for maintaining uterine quiescence, with upregulated S-nitrosoglutathione reductase (GSNOR) linked to preterm labor.

Purpose of the Study:

• To investigate nebivolol's effect on uterine smooth muscle relaxation.
• To test the hypothesis that nebivolol inhibits GSNOR activity.

Main Methods:

• Uterine smooth muscle strips from mice and humans were used.
• Oxytocin-induced contractions were measured in the presence of varying nebivolol concentrations.
• GSNOR activity and thioredoxin reductase inhibition were assessed.

Main Results:

• Nebivolol dose-dependently relaxed oxytocin-induced contractions in both mouse and human uterine smooth muscle.
• Nebivolol did not affect GSNOR activity.
• Nebivolol did not inhibit thioredoxin reductase.

Conclusions:

• Nebivolol effectively relaxes uterine smooth muscle, suggesting a potential role in managing preterm labor.
• Nebivolol's mechanism does not involve GSNOR inhibition.
• Nebivolol likely promotes uterine relaxation through increased nitric oxide synthase activity and beta-3 adrenergic stimulation.