Linda Vignozzi1, Annamaria Morelli1, Sandra Filippi2, Stefano Ambrosini3, Rosa Mancina1, Michaela Luconi4, Sara Mungai1, Gabriella Barbara Vannelli3, Xin-Hua Zhang1, Gianni Forti4, Mario Maggi5. 1. Andrology Unit, Florence, Italy. 2. Interdep. Laboratory of Functional and Cellular Pharmacology of Reproduction, Departments of Pharmacology and Clinical Physiopathology, University of Florence, Florence, Italy. 3. Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy. 4. Endocrinology Unit, Department of Clinical Physiopathology, Center for Research, Transfer and High Education DENOTHE, University of Florence, Florence, Italy. 5. Andrology Unit, Florence, Italy. Electronic address: m.maggi@DFC.UNIFI.IT.
Abstract
INTRODUCTION: The contractile RhoA/Rho-kinase (ROCK) signaling pathway is upregulated in penile tissue in animal models of experimental diabetes and has been proposed to contribute to diabetes-related erectile dysfunction (ED). AIM: To investigate the effect of testosterone (T) on the RhoA/ROCK signaling in diabetes. METHODS: We used two distinct animal models of chemical diabetes (alloxan-induced in the rabbit and streptozotocin-induced in the rat) with or not T supplementation. MAIN OUTCOME MEASURES: The effect of diabetes and T supplementation on RhoA/ROCK signaling was evaluated as responsiveness to the selective ROCK inhibitor Y-27632 either by "in vitro" contractility study (diabetic rabbit) or "in vivo" as erectile response elicited by intracavernous injections (diabetic rats). RhoA/ROCK gene and protein expression were also analyzed. RESULTS: In both models, hypogonadism was observed, characterized by reduced T plasma level and androgen-dependent accessory glands atrophy. Diabetic animals showed a significant increase in responsiveness to increasing concentrations of Y-27632. T substitution (30 mg/kg, weekly) completely prevented hypogonadism and diabetes-induced penile hypersensitivity to Y-27632. To test whether this effect was due to a T-dependent regulation of RhoA/ROCK gene expression, we measured RhoA/ROCK mRNA. Both isoforms of ROCK (ROCK1/ROCK2) were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) in rat penile samples. We found that ROCK1 mRNA was significantly increased (P < 0.05) in penile tissues from diabetic animals and maintained at the control values by T, as also confirmed by semiquantitative RT-PCR in rabbit. Conversely, RhoA and ROCK2 mRNA expression was not influenced either by diabetic condition or by T administration. Accordingly, ROCK1 protein expression, as evaluated by Western blot and immunohistochemistry analysis, was increased in penile samples from diabetic animals and normalized by T. CONCLUSIONS: Our data further support the hypothesis that the overexpression of RhoA/ROCK signaling contributes to diabetes-related ED. Moreover, treating hypogonadism in course of diabetes may maintain erectile function also by normalizing RhoA/ROCK pathway upregulation.
INTRODUCTION: The contractile RhoA/Rho-kinase (ROCK) signaling pathway is upregulated in penile tissue in animal models of experimental diabetes and has been proposed to contribute to diabetes-related erectile dysfunction (ED). AIM: To investigate the effect of testosterone (T) on the RhoA/ROCK signaling in diabetes. METHODS: We used two distinct animal models of chemical diabetes (alloxan-induced in the rabbit and streptozotocin-induced in the rat) with or not T supplementation. MAIN OUTCOME MEASURES: The effect of diabetes and T supplementation on RhoA/ROCK signaling was evaluated as responsiveness to the selective ROCK inhibitor Y-27632 either by "in vitro" contractility study (diabetic rabbit) or "in vivo" as erectile response elicited by intracavernous injections (diabeticrats). RhoA/ROCK gene and protein expression were also analyzed. RESULTS: In both models, hypogonadism was observed, characterized by reduced T plasma level and androgen-dependent accessory glands atrophy. Diabetic animals showed a significant increase in responsiveness to increasing concentrations of Y-27632. T substitution (30 mg/kg, weekly) completely prevented hypogonadism and diabetes-induced penilehypersensitivity to Y-27632. To test whether this effect was due to a T-dependent regulation of RhoA/ROCK gene expression, we measured RhoA/ROCK mRNA. Both isoforms of ROCK (ROCK1/ROCK2) were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) in rat penile samples. We found that ROCK1 mRNA was significantly increased (P < 0.05) in penile tissues from diabetic animals and maintained at the control values by T, as also confirmed by semiquantitative RT-PCR in rabbit. Conversely, RhoA and ROCK2 mRNA expression was not influenced either by diabetic condition or by T administration. Accordingly, ROCK1 protein expression, as evaluated by Western blot and immunohistochemistry analysis, was increased in penile samples from diabetic animals and normalized by T. CONCLUSIONS: Our data further support the hypothesis that the overexpression of RhoA/ROCK signaling contributes to diabetes-related ED. Moreover, treating hypogonadism in course of diabetes may maintain erectile function also by normalizing RhoA/ROCK pathway upregulation.
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