Resveratrol-nitric oxide donor hybrid effect on priapism in sickle cell and nitric oxide-deficient mouse

Abstract

Background: Children and adult with sickle cell disease (SCD) display priapism associated with low nitric oxide (NO) bioavailability and oxidative stress in penis.

Aim: This study aimed to evaluate the effects of hybrid compound RVT-FxMe, derived from resveratrol bearing a NO-donor subunit, on two murine model that display priapism phenotype, SCD transgenic mice and endothelial NO synthase gene-deficient (eNOS-/-) mice.

Methods: Wild-type, SCD, and eNOS-/- mice were treated with RVT-FxMe (25 mg/kg/d, 2 weeks).

Outcomes: Hematological parameters, concentration-response curves to acetylcholine (ACh) and sodium nitroprusside (SNP), as well as to electrical field stimulation (EFS), were obtained in mice corpus cavernosum strips.

Results: Corpus cavernosum relaxations to SNP and EFS were increased in eNOS-/- group, which were normalized by RVT-FxMe treatment. SCD mice exhibited an excessive CC relaxant response induced by ACh, EFS and SNP RVT-FxMe treatment did not change the increased relaxant responses to ACh, EFS and SNP in corpus cavernosum from SCD group.

Clinical translation: Excess of plasma hemoglobin in SCD may interfere in pharmacological activity of NO donors compounds.

Strength/limitations: While mechanistic data with promising potential is showed, the current study is not without limitations. RVT-FxMe effects in the mid- and long-term warrant complementary studies.

Conclusion: Treatment with RVT-FxMe reversed the enhanced NO-cGMP-mediated CC relaxations in eNOS-/- mice, but not in SCD mice; it is likely that excess of plasma hemoglobin in SCD mice act to inactivate NO before it reaches soluble guanylyl cyclase, avoiding restoration of NO bioavailability in penis.

Fig 1. Chemical structures of resveratrol and RVT-FxMe.

Fig 2. Hematological parameters of WT, eNOS^-/- and SCD mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data are shown as mean ± SEM of 6 mice per group. (A) Red blood cell, (B) hemoglobin and (C) plasma hemoglobin. One-way ANOVA: *P < .05 vs WT group.

Fig 3. Relaxation responses to electrical-field stimulation (EFS) in corpus cavernosum strips from WT and eNOS^-/- mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data were calculated relative to the maximal changes from the contraction produced by phenylephrine (10⁻⁵ M) in each tissue, which was taken as 100%. Data represent the mean ± SEM for 6 mice in each group. One-way ANOVA: *P < .05 vs WT + Vehicle, # P < .05 vs respective vehicle group.

Fig 4. Concentration-response curves to sodium nitroprusside (SNP) in corpus cavernosum strips from WT and eNOS^-/- mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data were calculated relative to the maximal changes from the contraction produced by phenylephrine (10⁻⁵ M) in each tissue, which was taken as 100%. Data represent the mean ± SEM for 6 mice in each group. One-way ANOVA: *P < .05 vs WT + Vehicle, # P < .05 vs respective vehicle group.

Fig 5. Concentration-response curves to acetylcholine (ACh) sodium nitroprusside (SNP) in corpus cavernosum strips from WT and SCD mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data were calculated relative to the maximal changes from the contraction produced by phenylephrine (10⁻⁵ M for WT mice and 3 × 10⁻⁶ M for SCD mice) in each tissue, which was taken as 100%. Data represent the mean ± SEM for 6 mice in each group. One-way ANOVA: *P < .05 vs WT + Vehicle.

Fig 6. Relaxation responses to electrical-field stimulation (EFS) in corpus cavernosum strips from WT and SCD mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data were calculated relative to the maximal changes from the contraction produced by phenylephrine (10⁻⁵ M for WT mice and 3 × 10⁻⁶ M for SCD mice) in each tissue, which was taken as 100%. Data represent the mean ± SEM for 6 mice in each group. *P < .05 vs WT + Vehicle.

Fig 7. cGMP levels in penises of WT, eNOS^-/- and SCD mice treated with RVT-FxMe (25 mg/kg/day, 2 weeks) or vehicle.

Data represent the mean ± SEM for 5 mice in each group. One-way ANOVA: *P < .05 vs WT + Vehicle, # P < .05 vs respective vehicle group.