Short hairpin rna targeting insulin-like growth fator binding protein-3 restores the bioavailability of insulin-like growth factor-1 in diabetic rats

IGFBP5 antisense and short hairpin RNA (shRNA) constructs improve erectile function by inducing cavernosum angiogenesis in diabetic mice

BACKGROUND

The incidence of diabetic erectile dysfunction (ED) is rapidly increasing, and due to the severe angiopathy caused by diabetes, current drugs are ineffective at treating ED. Insulin-like growth factor-binding protein 5 (IGFBP5) promotes cell death and induces apoptosis in various cell types.

OBJECTIVES

To evaluate the effectiveness of IGFBP5 knockdown in improving erectile function in diabetic mice.

MATERIALS AND METHODS

Diabetes was induced by injecting streptozotocin (STZ) intraperitoneally into male 8-week-old C57BL/6 mice. Eight weeks after diabetes induction, mice were divided into four groups: a nondiabetic control group and three STZ-induced diabetic mice groups, which were administered intracavernous injections of phosphate buffered saline, scrambled control shRNA, or shRNA targeting mouse IGFBP5 (shIGFBP5) lentivirus particles. Two weeks later, we measured erectile function by electrically stimulating the bilateral cavernous nerve. To mimic diabetic angiopathy, primary cavernous endothelial cells (MCECs) from healthy mice were cultured and treated with glucose.

RESULTS

IGFBP5 expression in MCECs or cavernous tissues were significantly increased under diabetic conditions, and knockdown of IGFBP5 induced MCECs angiogenic activity under high-glucose conditions. STZ-induced diabetic mice had reduced erectile function, but shIGFBP5 treatment resulted in significant improvements (to 90% of the nondiabetic control group level). Furthermore, in diabetic mice, numbers of cavernous endothelial cells, pericytes, and neuronal cells were increased by shIGFBP5 treatment, which also increased eNOS Ser¹¹⁷⁷ phosphorylation, decreased permeability and apoptosis of cavernous endothelial cells. In addition, IGFBP5 was found to mediate the AKT, ERK, p38 signaling pathways.

DISCUSSION AND CONCLUSION

Knockdown of IGFBP5 improved erectile function in diabetic mice by promoting cell proliferation and reducing apoptosis and permeability. Local inhibition of IGFBP5 expression may provide a new treatment strategy for diabetic ED and other ischemic vascular or neurological diseases.

Upregulated IGFBP3 with Aging Is Involved in Modulating Apoptosis, Oxidative Stress, and Fibrosis: A Target of Age-Related Erectile Dysfunction

Aging has been deemed the primary factor in erectile dysfunction (ED). Herein, age-related changes in the erectile response and histomorphology were detected, and the relationship between aging and ED was investigated based on gene expression levels. Thirty male Sprague–Dawley (SD) rats were randomly divided into 6 groups, and intracavernous pressure (ICP) and mean arterial pressure (MAP) were measured. Subsequently, the corpus cavernosum (CC) was harvested and prepared for histological examinations of apoptosis, oxidative stress (OS), and fibrosis. Then, the microarray dataset (GSE10804) was analyzed to identify differentially expressed genes (DEGs) in ED progression, and hub genes were selected. In addition, aged CC smooth muscle cells (CCSMCs) were isolated to evaluate the function of the hub gene by siRNA interference, qRT–PCR, immunofluorescence staining, enzyme-linked immunosorbent assay, western blot analysis, CCK-8 assay, EdU staining, and flow cytometry approaches. The ICP/MAP and smooth muscle cell (SMC)/collagen ratios declined with aging, while apoptosis and OS levels increased with aging. The enriched functions and pathways of the DEGs were investigated, and 15 hub genes were identified, among which IGFBP3 was significantly upregulated. The IGFBP3 upregulation was verified in the CC of aging rats. Furthermore, aged CCSMCs were transfected with siRNA to knock down IGFBP3 expression. The viability and proliferation of the CCSMCs increased, while apoptosis, OS, and fibrosis decreased. Our findings demonstrate that the erectile response of SD rats declines in parallel with enhanced CC apoptosis, OS, and fibrosis with aging. Upregulation of IGFBP3 plays an important role; furthermore, downregulation of IGFBP3 improves the viability and proliferation of CCSMCs and alleviates apoptosis, OS, and fibrosis. Thus, IGFBP3 is a potential therapeutic target for age-related ED.

Pharmacotherapy for erectile dysfunction in diabetic males

INTRODUCTION

Numerous studies have highlighted the intimate association between erectile dysfunction (ED) and diabetes mellitus (DM). However, the true pathogenesis of ED among diabetic men has not yet been fully discovered. The treatment of ED in diabetic patients remains an interesting area of research. The last two decades have witnessed phenomenal advances in the management of ED with the efficacy of pharmacotherapy for ED in diabetic patients encouraging, especially with introduction of innovative conservative tools for treatment.

AREAS COVERED

The aim of this review is to discuss the currently available information on ED pharmacotherapy in diabetic males and provide an expert perspective on the current treatment strategies.

EXPERT OPINION

Conservative treatment remains the initial step for the treatment of ED in diabetic patients. This kind of therapy consists of different modalities including: oral treatments, intracavernosal pharmacotherapy, and evolving modalities such as soluble guanylate cyclase activators, stem cells (SCs), and alternative treatments such as herbal treatment and transdermal/topical pharmacotherapy. However, it should be noted that the currently available pharmacotherapy is still far from ideal. One hopes to witness new drugs and technologies that may revolutionize ED treatment in the future, especially in such complex cases as DM.