Effects of eupatilin on the contractility of corpus cavernosal smooth muscle through nitric oxide-independent pathways

Corpora cavernosa fibroblasts mediate penile erection

Penile erection is mediated by the corpora cavernosa, a trabecular-like vascular bed that enlarges upon vasodilation, but its regulation is not completely understood. Here, we show that perivascular fibroblasts in the corpora cavernosa support vasodilation by reducing norepinephrine availability. The effect on penile blood flow depends on the number of fibroblasts, which is regulated by erectile activity. Erection dynamically alters the positional arrangement of fibroblasts, temporarily down-regulating Notch signaling. Inhibition of Notch increases fibroblast numbers and consequently raises penile blood flow. Continuous Notch activation lowers fibroblast numbers and reduces penile blood perfusion. Recurrent erections stimulate fibroblast proliferation and limit vasoconstriction, whereas aging reduces the number of fibroblasts and lowers penile blood flow. Our findings reveal adaptive, erectile activity-dependent modulation of penile blood flow by fibroblasts.

Erectile Dysfunction: Treatments, Advances and New Therapeutic Strategies

Erectile dysfunction (ED) is the inability to get and maintain an adequate penile erection for satisfactory sexual intercourse. Due to its negative impacts on men's life quality and increase during aging (40% of men between 40 and 70 years), ED has always attracted researchers of different disciplines, from urology, andrology and neuropharmacology to regenerative medicine, and vascular and prosthesis implant surgery. Locally and/or centrally acting drugs are used to treat ED, e.g., phosphodiesterase 5 inhibitors (first in the list) given orally, and phentolamine, prostaglandin E1 and papaverine injected intracavernously. Preclinical data also show that dopamine D4 receptor agonists, oxytocin and α-MSH analogues may have a role in ED treatment. However, since pro-erectile drugs are given on demand and are not always efficacious, new strategies are being tested for long lasting cures of ED. These include regenerative therapies, e.g., stem cells, plasma-enriched platelets and extracorporeal shock wave treatments to cure damaged erectile tissues. Although fascinating, these therapies are laborious, expensive and not easily reproducible. This leaves old vacuum erection devices and penile prostheses as the only way to get an artificial erection and sexual intercourse with intractable ED, with penile prosthesis used only by accurately selected patients.

A Systematic Review on Rho-Kinase as a Potential Therapeutic Target for the Treatment of Erectile Dysfunction

Background

Erectile dysfunction (ED) is a common clinical condition with limited treatment options. The main aim of the present systematic review was to synthesize information on Rho-kinase as a novel therapeutic approach for the treatment of ED.

Methods

We performed a systematic literature study in PubMed, Google Scholar and Scopus. Included studies were original articles studied the role of Rho-kinase in the pathogenesis and/or new treatment approach for ED in animal models and clinical studies, published between 2014 and 2019. Data derived from each study were study design used, interventions applied and main treatment outcomes. The quality of the selected articles was assessed by CAMARADES criteria and data were analyzed using descriptive statistics.

Results

A total of 1067 original articles were retrieved in the given period and eighteen papers met our inclusion criteria. Five articles explain the role of Rho-kinase in ED pathogenesis using different models such as cavernous nerve crush injury, heart failure-induced ED, vasculogenic and post-radical prostatectomy ED, diabetes-induced ED and age-related ED. Other ten papers explain the role of novel drugs evaluated for ED treatment by targeting Rho-kinase as a new approach for ED therapy. The rest three papers discuss the role of plant extracts used by traditional society for the treatment of ED and assess their potential function in targeting Rho-kinase in animal models. The penile erectile functional index has shown that the ratio of intracavernosal pressure to mean arterial pressure (ICP/MAP) was decreased due to age and various chronic diseases. Whilst, ROCK I and ROCK II expression were increased. Western blot findings have also shown that ROCK II and MYPT-1 phosphorylation rates increased in cavernous tissue after ED induction. Besides, compounds which can inhibit the action of Rho-kinase activity showed relaxation of the corpus cavernosum, decrease in corporal fibrosis, and alleviate increased apoptosis and caspase-3 activity in an NO-independent manner. Moreover, histological and molecular dysregulation have been improved by inhibition of Rho-kinase.

Conclusion

Targeting Rho-kinase may be a possible target for the treatment of ED secondary to specific causes, and Rho-kinase inhibitors may be a new drug family for the treatment of ED. However, this requires further studies for in-depth understanding.

A Botanical-Based Equine Nutraceutical Reduces Gastric Smooth Muscle Contractile Force In Vitro

The objective of this study was to evaluate the effect of a botanical-based equine nutraceutical on contractility of gastric smooth muscle in vitro. Gastric ulcers are prevalent in performance horses and negatively impact horse welfare. Gastric hypermotility has been positively associated with the development of gastric ulceration in nonequine species, and reduction of hypermotility may be protective against their development. Stomachs from 12 pigs processed for food at a provincially inspected abattoir were collected within 1 hour of slaughter. Explants of nonglandular gastric tissue were prepared and suspended in a tissue bath, attached to a force transducer, in the presence or absence of a simulated digest extract of the nutraceutical. Tissue was stimulated to contract using increasing doses of acetylcholine. Peak and mean contractile force over 1 and 2 minutes after exposure to acetylcholine were measured. Exposure of gastric smooth muscle to the nutraceutical significantly reduced contractility of the tissue. These data provide support for the use of this nutraceutical to reduce contractility of nonglandular gastric smooth muscle and may indicate a protective effect of this nutraceutical in horses with mechanically induced gastric ulcers. Future studies are needed to clarify the role of gastric hypermotility on development of equine gastric ulcers and to determine the effect of this nutraceutical on equine gastric contractility and ulcerogenesis in vivo.

Engineered Mesenchymal Stem Cells Expressing Stromal Cell-derived Factor-1 Improve Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Effective therapies for erectile dysfunction (ED) associated with diabetes mellitus (DM) are needed. In this study, the effects of stromal cell-derived factor-1 (SDF-1)-expressing engineered mesenchymal stem cells (SDF-1 eMSCs) and the relevant mechanisms in the corpus cavernosum of a streptozotocin (STZ)-induced DM ED rat model were evaluated. In a randomized controlled trial, Sprague–Dawley (SD) rats (n = 48) were divided into four groups (n = 12/group): Normal (control), DM ED (diabetes induced by STZ), DM ED + BM-MSC (treated with bone marrow [BM]-derived MSCs), and DM ED + SDF-1 eMSC (treated with SDF-1-expressing BM-MSCs). After four weeks, intracavernosal pressure (ICP), an indicator of erectile function, was 0.75 ± 0.07 in the normal group, 0.27 ± 0.08 in the DM ED group, 0.42 ± 0.11 in the DM ED + BM-MSC group, and 0.58 ± 0.11 in the DM ED + SDF-1 eMSC group. BM-MSCs, especially SDF-1 eMSCs, improved ED (p < 0.05). SDF-1 eMSC treatment improved the smooth muscle content in the corpus cavernosum (p < 0.05). As SDF-1 expression increased, ED recovery improved. In the SDF-1 eMSC group, levels of neuronal nitric oxide synthase (nNOS) and phosphorylated endothelial NOS (p-eNOS) were higher than those in other groups (p < 0.05). In addition, high stromal cell-derived factor-1 (SDF-1) expression was associated with increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in DM ED rats (p < 0.05). Higher levels of phosphorylated protein kinase B (p-AKT)/protein kinase B (AKT) (p < 0.05) and B-cell lymphoma-2 (Bcl-2) and lower levels of the apoptosis factors Bcl2-associated x (Bax) and caspase-3 were observed in the MSC-treated group than in the DM ED group (p < 0.05). SDF-1 eMSCs showed beneficial effects on recovery from erectile function.