Expression and function of ryanodine receptors in rabbit penile corpus cavernosum smooth muscle cells

Simvastatin alleviated diabetes mellitus-induced erectile dysfunction in rats by enhancing AMPK pathway-induced autophagy

BACKGROUND

Diabetes mellitus-induced erectile dysfunction is a common diabetic complication, and new therapeutics and the pathogenesis of diabetes mellitus-induced erectile dysfunction need to be investigated.

OBJECTIVES

The aim was to investigate the pathogenesis of diabetes mellitus-induced erectile dysfunction and the pharmacological mechanism of simvastatin treatment in diabetes mellitus-induced erectile dysfunction model rats.

MATERIALS AND METHODS

A total of 86 male Sprague Dawley rats aged 8 weeks old were used in this study. The rats were divided into three groups: control (normal), diabetes mellitus-induced erectile dysfunction (streptozotocin-injected), and diabetes mellitus-induced erectile dysfunction + simvastatin (sim). Each group was subdivided into two subgroups for in vitro and in vivo analyses. A bioinformatics method was used to detect differences in gene expression in the corpus cavernosum between normal and diabetes mellitus-induced erectile dysfunction rats. Erectile function was measured by a cavernous nerve electrostimulation test. Corpus cavernosum fibrosis was assessed by Masson staining and Western blotting. Immunofluorescence and Western blotting were performed to explore the differential expression of autophagy-related genes and the AMPK-SKP2-CARM1 pathway genes in rat cavernous smooth muscle cells and the corpus cavernosum. The autophagosomes of the corpus cavernosum tissue were observed by transmission electron microscopy.

RESULTS

Autophagy-related genes and pathways (the AMPK and FoxO pathway) were identified by bioinformatics analysis and confirmed at the protein level. Simvastatin, an AMPK agonist, was used to treat diabetes mellitus-induced erectile dysfunction rats for 8 weeks, demonstrating that erectile function was improved for 80.5% (P < .05) of rats. Corpus cavernosum fibrosis was alleviated (P < .05), and autophagy was further enhanced (P < .05); these results might be partially caused by AMPK-SKP2-CARM1 pathway activation (P < .05).

DISCUSSION AND CONCLUSION

Simvastatin could enhance protective autophagy by activating the AMPK-SKP2-CARM1 pathway to improve erectile function in diabetes mellitus-induced erectile dysfunction rats.

Reduced expression of myocardin and serum response factor in the cavernous tissue of diabetic rats

This study aimed to investigate the expression of myocardin and serum response factor (SRF) in the cavernous tissue of diabetic rats. The experimental diabetes model was induced in 8-week-old male Sprague-Dawley rats (200-220 g) by a single administration of streptozotocin. Both the diabetes mellitus group (DM group, n = 20) and the control group (NDM group, n = 10) were injected with a low dose of apomorphine to allow for the measurement and comparison of the corresponding penile erections. Western blot and qRT-PCR were used to determine the protein and mRNA expression levels of myocardin and SRF. Erectile function was significantly decreased in the DM group compared with the control group (P < 0.001). The mRNA and protein expression levels of myocardin and SRF were reduced in the cavernous tissue of diabetic rats compared with the control group (P < 0.001). It is concluded that diabetes inhibits the mRNA and protein expression of both myocardin and SRF in the cavernous tissue. This could play a key role in the development of erectile dysfunction in diabetic rats.