Icariin modulates eNOS activity via effect on post‐translational protein‐protein interactions to improve erectile function of spontaneously hypertensive rats

Abstract

Background Type 5 phosphodiesterase inhibitor (PDE5I) has become the first‐line treatment for erectile dysfunction (ED). However, its effective rate for hypertension ED is only 60%‐70%. How to improve the efficacy of ED treatment is the focus of current research. Objective To explore whether icariin can improve the erectile function of spontaneously hypertensive rats (SHR) by affecting post‐translational protein‐protein interactions to regulate endothelial nitric oxide synthetase (eNOS) activity. Method Twelve‐week‐old healthy male SHR rats and Wistar‐Kyoto rats (WKY) were randomly divided into four groups: SHR control group, SHR + icariin (10 mg/kg·d gavage) treatment group, WKY control group, and WKY + icariin (10 mg/kg·d gavage) treatment group (n = 5). After 4 weeks, the maximum penile intracavernous pressure/mean arterial pressure (ICPmax/MAP), the expression of heat‐shock protein 90 (Hsp90), caveolin‐1, calmodulin, p‐eNOS, and eNOS in penile cavernous tissue and the content of nitric oxide (NO) and cGMP were measured. The interaction between eNOS and Hsp90, caveolin‐1, and calmodulin were detected by immunoprecipitation. Result The ICPmax/MAP in the SHR + icariin treatment group (0.08 ± 0.01, 0.23 ± 0.07, 0.40 ± 0.05) was significantly higher than the SHR group (0.03 ± 0.01, 0.13 ± 0.03, 0.21 ± 0.02) under 3V and 5V electrical stimulations (P < .05). Compared with the SHR group, the expression of HSP90, calmodulin, P‐eNOS, eNOS, and P‐eNOS/eNOS in the penile cavernous tissue of rats in the WKY group and the SHR + icariin treatment group were significantly increased (P < .05), and the expression of caveolin‐1 was significantly decreased (P < .05). The NO content (2.16 ± 0.22 μmol/g) and cGMP concentration (3.69 ± 0.12 pmol/mg) in the SHR + icariin treatment group were significantly higher than those in the SHR group (1.01 ± 0.14 μmol/g, 2.31 ± 0.22 pmol/mg) (P < .05). Compared with the SHR group, the interaction between eNOS and HSP90 in the cavernosa of the rats in the SHR + icariin treatment group was significantly increased (P < .05), the interaction between eNOS and caveolin‐1 was significantly decreased (P < .01), and the interaction between eNOS and calmodulin did not significantly change. Discussion and Conclusion Up‐regulating the expression of HSP90 and calmodulin and inhibiting caveolin‐1 in SHR corpus cavernosum, promoting the interaction between eNOS and HSP90, inhibiting the interaction between eNOS and caveolin‐1, increasing p‐eNOS/eNOS, may be the mechanism of icariin that improves SHR erectile function.

Comparative Efficacy of Antihypertensive Agents in Flow-Mediated Vasodilation of Patients with Hypertension: Network Meta-Analysis of Randomized Controlled Trial

“…ARB can promote the release of nitric oxide and accelerate the effect of acetylcholine on endothelium-dependent vasodilation [ 69 ]. These compounds can reverse endothelial dysfunction spontaneously hypertensive rats [ 70 ] and ameliorate FMD in patients with hypertension. CCB not only effectively reduces blood pressure but also increases the production of endothelial nitric oxide synthase, thereby improving nitric oxide bioavailability and endothelial function [ 7 ].…”

Diabetes associated with hypertension exacerbated oxidative stress–mediated inflammation, apoptosis and autophagy leading to erectile dysfunction in rats

“…Elevated MAP-like SHR induced hypertension could induce ED with the decreased the level of maximum penile intracavernous pressure/MAP (ICPmax/MAP) by the decreased eNOS and HSP90 interaction, 34 and a lower eNOS expression in sinusoidal endothelium. 35 These messages informed that elevated MAP could reduce ICP by the functional and structural alteration in vessels as well as in the cavernous spaces of the erectile tissue.…”

Effect of the icariin on endothelial microparticles, endothelial progenitor cells, platelets, and erectile function in spontaneously hypertensive rats

“…After treatment with ICA, the ICP max /MAP significantly improved, which is consistent with the previous experiments. [4][5][6] A large number of studies have shown that EMP and EPC are closely related to arterial ED. 14,15,17 In this study, we further investigated the effect of ICA on EMP, EPC, and platelets in SHR and its relationship with erectile function by FCM.…”

“…[4][5][6] These results indicated that ICA could improve the erectile function of SHR by up-regulating the eNOS /nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway and inhibiting the RhoA/Rho kinase signaling pathway in the corpus cavernosum tissue of SHR. [4][5][6] Other studies have also found that ICA can increase the expression of eNOS, nNOS, and inducible NO synthase (iNOS)…”

“…Our previous studies suggested that ICA increases endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), heat‐shock protein 90 (HSP90), and calmodulin expression and decreases the expression of phosphodiesterase type 5 (PDE5), Rho‐associated coiled‐coil containing protein kinase 2, and caveolin‐1 in the corpus cavernosum of spontaneously hypertensive rats (SHR) 4–6 . Moreover, ICA increases phosphorylation of eNOS in the corpus cavernosum tissue of SHR and decreases the ratio of eNOS monomers/dimmers 4–6 . These results indicated that ICA could improve the erectile function of SHR by up‐regulating the eNOS /nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway and inhibiting the RhoA/Rho kinase signaling pathway in the corpus cavernosum tissue of SHR 4–6 .…”