Initial characterization of hydrogen sulfide effects in female sexual function

Area of Science:

• Physiology
• Biochemistry
• Pharmacology

Background:

• Hydrogen sulfide (H(2)S) exhibits vasodilatory and smooth muscle relaxant effects in male models, implying a physiological role in erectile function.
• The presence and mechanism of the H(2)S pathway in female sexual physiology remain largely unexplored.

Purpose of the Study:

• To investigate the existence and functional mechanism of the H(2)S pathway in female sexual physiology.
• To determine the relaxant effects of H(2)S on female genital tract smooth muscles.

Main Methods:

• Isometric tension studies were performed on vaginal and clitoral smooth muscle strips from New Zealand white rabbits.
• Responses to sodium hydrosulfide hydrate (NaHS) were assessed in the presence of inhibitors for nitric oxide synthase (NOS), guanylate cyclase, and K+(ATP) channels.
• Plasma and tissue H(2)S levels were quantified, and the expression of cystathionine gamma-lyase (CSE) and cystathionine beta-synthase (CBS) proteins was analyzed via Western blotting.

Main Results:

• NaHS induced significant, concentration-dependent relaxation of vaginal and clitoral smooth muscles.
• The relaxant effects were partially inhibited by NOS, guanylate cyclase, and K+(ATP) channel blockers.
• Endogenous H(2)S was detected in plasma and genital tissues, with detectable levels of CSE and CBS proteins.

Conclusions:

• H(2)S exerts a smooth muscle relaxant effect in the female genital tract.
• The H(2)S pathway, involving cyclic adenosine 3':5'-monophosphate, nitric oxide-cyclic guanosine monophosphate, and K+(ATP) channels, contributes to female sexual responses.
• These findings highlight a potential physiological role for H(2)S in female sexual function.