Time-dependent effect of orchidectomy on vascular nitric oxide and thromboxane A2 release. Functional implications to control cell proliferation through activation of the epidermal growth factor receptor

• Published in: PloS one Vol. 9; no. 7; p. e102523
• Main Authors: del Campo, Marta, Sagredo, Ana, del Campo, Lara, Villalobo, Antonio, Ferrer, Mercedes
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.07.2014; Public Library of Science (PLoS)
• Subjects: Acetylcholine; Acetylcholine - pharmacology; Animals; Aorta; Aorta - drug effects; Aorta - metabolism; Arteries; Biology and Life Sciences; Cell activation; Cell growth; Cell proliferation; Cell Proliferation - drug effects; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Epidermal growth factor; Epidermal Growth Factor - pharmacology; Epidermal growth factor receptors; ErbB Receptors - agonists; ErbB Receptors - genetics; ErbB Receptors - metabolism; Gene Expression Regulation; Kinases; Male; Medicine and Health Sciences; Mesenteric Arteries - drug effects; Mesenteric Arteries - metabolism; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Muscles; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide - metabolism; Orchidectomy; Orchiectomy; Rats; Rats, Sprague-Dawley; Rodents; Signal Transduction; Signaling; Smooth muscle; Testosterone; Testosterone - pharmacology; Thromboxane A2; Thromboxane A2 - biosynthesis; Thromboxane A2 - metabolism; Time Factors; Tissue Culture Techniques; Veins & arteries; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0102523

This study analyzes whether the release of nitric oxide (NO) and thromboxane A2 (TXA2) depends on the time lapsed since gonadal function is lost, and their correlation with the proliferation of vascular smooth muscle cells (VSMC) mediated by the epidermal growth factor receptor (EGFR). For this purpose, aortic and mesenteric artery segments from control and 6-weeks or 5-months orchidectomized rats were used to measure NO and TXA2 release. The results showed that the basal and acetylcholine (ACh)-induced NO release were decreased 6 weeks post-orchidectomy both in aorta and mesenteric artery, but were recovered 5 months thereafter up to levels similar to those found in arteries from control rats. The basal and ACh-induced TXA2 release increased in aorta and mesenteric artery 6 weeks post-orchidectomy, and was maintained at high levels 5 months thereafter. Since we previously observed that orchidectomy, which decreased testosterone level, enlarged the muscular layer of mesenteric arteries, the effect of testosterone on VSMC proliferation was analyzed. The results showed that treatment of cultured VSMC with testosterone downregulated mitogenic signaling pathways initiated by the ligand-dependent activation of the EGFR. In contrast, the EGFR pathways were constitutively active in mesenteric arteries of long-term orchidectomized rats. Thus, the exposure of mesenteric arteries from control rats to epidermal growth factor (EGF) induced the activation of EGFR signaling pathways. However, the addition of EGF to arteries from orchidectomized rats failed to induce a further activation of these pathways. In conclusion, this study shows that the release of NO depends on the time lapsed since the gonadal function is lost, while the release of TXA2 is already increased after short periods post-orchidectomy. The alterations in these signaling molecules could contribute to the constitutive activation of the EGFR and its downstream signaling pathways after long period post-orchidectomy enhancing the proliferation of the vascular muscular layer.