Expression profile of endothelin receptors (ETA and ETB) and microRNAs-155 and -199 in the corpus cavernosum of rats submitted to chronic alcoholism and diabetes mellitus

Abstract

Recent evidence shows that chronic ethanol consumption increases endothelin (ET)-1 induced sustained contraction of trabecular smooth muscle cells of the corpora cavernosa in corpus cavernosum of rats by a mechanism that involves increased expression of ETA and ETB receptors. Our goal was to evaluate the effects of alcohol and diabetes and their relationship to miRNA-155, miRNA-199 and endothelin receptors in the corpus cavernosum and blood of rats submitted to the experimental model of diabetes mellitus and chronic alcoholism. Forty-eight male Wistar rats were divided into four groups: control (C), alcoholic (A), diabetic (D), and alcoholic-diabetic (AD). Samples of the corpus cavernosum were prepared to study the protein expression of endothelin receptors by immunohistochemistry and expression of miRNAs-155 and -199 in serum and the cavernous tissue. Immunostaining for endothelin receptors was markedly higher in the A, D, and AD groups than in the C group. Moreover, a significant hypoexpression of the miRNA-199 in the corpus cavernosum tissue from the AD group was observed, compared to the C group. When analyzing the microRNA profile in blood, a significant hypoexpression of miRNA-155 in the AD group was observed compared to the C group. The miRNA-199 analysis demonstrated significant hypoexpression in D and AD groups compared to the C group. Our findings in corpus cavernosum showed downregulated miRNA-155 and miRNA-199 levels associated with upregulated protein expression and unaltered mRNA expression of ET receptors suggesting decreased ET receptor turnover, which can contribute to erectile dysfunction in diabetic rats exposed to high alcohol levels.

Figure 1.. Representative immunohistochemical photomicrography of the overall expression of endothelin B (Panel A) and A (Panel B) protein in cross-section of the rat cavernous bodies of the alcoholic-diabetic group. Cavernous spaces (EC) and positive markings (arrows) are indicated. Magnification: 400×. The expression of endothelin B and A receptors in corpus cavernosum muscle can be observed in brown.

Figure 2.. Representative immunohistochemical photomicrography of the overall expression of endothelin B (Panel A) and A (Panel B) protein in cross-section of the rat cavernous bodies of the alcoholic-diabetic group. Diffuse marking on the erectile tissue can be seen, especially close to the tunica albuginea for endothelin B. Cavernous body (CC); Spongy body (CE). Magnification: 50×.

Figure 3.. Mean (±standard error) of endothelin A (ET_A) and B (ET_B) expression in cavernous tissue samples of the groups studied. There were no significant differences among the groups (Kruskal-Wallis test).

Figure 4.. Mean (±standard error) of microRNAs-155 and -199 expression in the cavernous tissue samples of the groups studied. *P<0.05, compared to the control group (Kruskal-Wallis test, Dunn's post-test).

Figure 5.. Mean (±standard error) of microRNA-155 and -199 expression in blood samples of the groups studied. *P<0.05, compared to the control group (Kruskal-Wallis test, Dunn's post-test).