Freeman Brian M, Univers Junior, Fisher Richard K, Kirkpatrick Stacy S, Klein Frederick A, Freeman Michael B, Mountain Deidra J H, Grandas Oscar H
Department of Surgery, University of Tennessee Graduate School of Medicine, Knoxville, Tennessee.
Department of Surgery, University of Tennessee Graduate School of Medicine, Knoxville, Tennessee.
J Surg Res. 2017 Jan;207:53-62. doi: 10.1016/j.jss.2016.08.016. Epub 2016 Aug 10.
Androgen deficiency (AD) is associated with increased risk of vascular disease. Dysfunctional remodeling of the vessel wall and atypical proliferative potential of vascular smooth muscle cells (VSMCs) are fundamental processes in the development of intimal hyperplasia (IH). We have demonstrated an inverse relationship between dihydrotestosterone (DHT) levels, matrix metalloproteinase activity, and VSMC migration and proliferation in vitro. Here, we investigated the role of AD and testosterone (TST) replacement in IH development in an animal model of vascular injury to elucidate mechanisms modulated by AD that could be playing a role in the development of vascular pathogenesis.
Aged orchiectomized male rats underwent TST supplementation via controlled release pellet (0.5-35 mg). Young adult and middle-age adult intact (MI) and orchiectomized placebo (Plac) groups served as controls. All groups underwent balloon angioplasty of the left common carotid at a 14-d post-TST. Carotid tissue was collected at a 14-d post-balloon angioplasty and subjected to morphologic and immunohistochemical analyses. Human male VSMCs were treated with DHT (0-3000 nM) for 24 h then subjected to quantitative PCR for gene expression analyses and costained for F-actin and G-actin for visualization of cytoskeletal organization.
I:M ratio was increased in Plac, subphysiological, low-physiological, and high pharmacologic level TST animals compared with MI controls but was decreased with high-physiological TST supplementation. Injury-induced expression of previously defined matrix metalloproteinase remodeling enzymes was not significantly affected by TST status. Urotensin (UTS) receptor (UTSR) staining was low in injured vessels of all young adult intact, MI, and Plac controls but was significantly upregulated in all groups receiving exogenous TST supplementation, irrespective of dose. In vitro DHT exposure increased the expression of UTSR in VSMCs in a dose-dependent manner. However, this did not correlate with any change in proliferative markers. F:G actin staining revealed that DHT-induced cytoskeletal organization in a dose-dependent manner.
AD increased IH development in response to vascular injury, whereas physiological TST replacement attenuated this effect. AD-induced IH occurs independent of matrix remodeling mechanisms known to be heavily involved in vascular dysfunction, and AD alone does not affect the UTS and/or UTSR mechanism. Exogenous TST and/or DHT increases UTSR pathway signaling in vitro and in vivo. This modulation correlates to a shift in cytoskeletal organization and may exacerbate vasoconstrictive pathogenesis. While physiological TST replacement attenuates AD-modulated IH development, its UTS-mediated effect on vasotone may prove deleterious to overall vascular function.
雄激素缺乏（AD）与血管疾病风险增加相关。血管壁功能失调性重塑以及血管平滑肌细胞（VSMC）的非典型增殖潜能是内膜增生（IH）发展的基本过程。我们已在体外证实二氢睾酮（DHT）水平、基质金属蛋白酶活性与VSMC迁移和增殖之间存在负相关关系。在此，我们在血管损伤动物模型中研究了AD和睾酮（TST）替代在IH发展中的作用，以阐明AD所调节的可能在血管发病机制发展中起作用的机制。
老年去势雄性大鼠通过控释微丸（0.5 - 35毫克）进行TST补充。年轻成年和中年成年完整（MI）及去势安慰剂（Plac）组作为对照。所有组在TST补充后14天对左颈总动脉进行球囊血管成形术。在球囊血管成形术后14天收集颈动脉组织并进行形态学和免疫组织化学分析。人男性VSMC用DHT（0 - 3000纳摩尔）处理24小时，然后进行定量PCR以进行基因表达分析，并对F - 肌动蛋白和G - 肌动蛋白进行共染色以观察细胞骨架组织。
与MI对照组相比，Plac组、亚生理水平、低生理水平和高药理水平TST动物的I:M比值升高，但高生理水平TST补充使其降低。先前定义的基质金属蛋白酶重塑酶的损伤诱导表达不受TST状态的显著影响。在所有年轻成年完整、MI和Plac对照组的损伤血管中，尾加压素（UTS）受体（UTSR）染色较低，但在所有接受外源性TST补充的组中均显著上调，与剂量无关。体外DHT暴露以剂量依赖性方式增加VSMC中UTSR的表达。然而，这与增殖标志物的任何变化均无关联。F:G肌动蛋白染色显示DHT以剂量依赖性方式诱导细胞骨架组织。
AD会增加血管损伤后IH的发展，而生理性TST替代可减轻这种效应。AD诱导的IH独立于已知大量参与血管功能障碍的基质重塑机制而发生，且单独的AD不影响UTS和/或UTSR机制。外源性TST和/或DHT在体外和体内均增加UTSR途径信号传导。这种调节与细胞骨架组织的改变相关，可能会加剧血管收缩性发病机制。虽然生理性TST替代可减轻AD调节的IH发展，但其UTS介导的对血管张力的影响可能对整体血管功能有害。
