Influence of Androgen Receptor in Vascular Cells on Reperfusion following Hindlimb Ischaemia.

Junxi Wu,Lee B Smith,Martin A Denvir,Agnieszka Korczak,Kaloyan Takov,Patrick W F Hadoke,Alain-Pierre Gadeau

doi:10.1371/journal.pone.0154987

Abstract

AimsStudies in global androgen receptor knockout (G-ARKO) and orchidectomised mice suggest that androgen accelerates reperfusion of the ischaemic hindlimb by stimulating angiogenesis. This investigation used novel, vascular cell-specific ARKO mice to address the hypothesis that the impaired hindlimb reperfusion in G-ARKO mice was due to loss of AR from cells in the vascular wall.Methods and ResultsMice with selective deletion of AR (ARKO) from vascular smooth muscle cells (SM-ARKO), endothelial cells (VE-ARKO), or both (SM/VE-ARKO) were compared with wild type (WT) controls. Hindlimb ischaemia was induced in these mice by ligation and removal of the femoral artery. Post-operative reperfusion was reduced in SM-ARKO and SM/VE-ARKO mice. Immunohistochemistry indicated that this was accompanied by a reduced density of smooth muscle actin-positive vessels but no change in the density of isolectin B4-positive vessels in the gastrocnemius muscle. Deletion of AR from the endothelium (VE-ARKO) did not alter post-operative reperfusion or vessel density. In an ex vivo (aortic ring culture) model of angiogenesis, AR was not detected in vascular outgrowths and angiogenesis was not altered by vascular ARKO or by exposure to dihydrotestosterone (DHT 10−10–10-7M; 6 days).ConclusionThese results suggest that loss of AR from vascular smooth muscle, but not from the endothelium, contributes to impaired reperfusion in the ischaemic hindlimb of G-ARKO. Impaired reperfusion was associated with reduced collateral formation rather than reduced angiogenesis.

Highlights

Global androgen receptor (AR) knockout (G-ARKO) in mice was recently shown to inhibit reperfusion in the ischaemic hindlimb, a model that involves both angiogenesis and arteriogenesis [1]
Hindlimb ischaemia was induced in these mice by ligation and removal of the femoral artery
In an ex vivo model of angiogenesis, AR was not detected in vascular outgrowths and angiogenesis was not altered by vascular ARKO or by exposure to dihydrotestosterone (DHT 10−10–10-7M; 6 days)

Summary

Introduction

Global androgen receptor (AR) knockout (G-ARKO) in mice was recently shown to inhibit reperfusion in the ischaemic hindlimb, a model that involves both angiogenesis (endothelial sprouting and formation of new capillaries) and arteriogenesis (growth of pre-existing small collateral arteries/arterioles; known as collateral growth) [1] This impaired reperfusion was linked to reduced angiogenesis since it was associated with lower vascular density in hindlimb muscles [1]. Since ECs have a central role in the formation of new vascular networks, it has been proposed that androgen regulates angiogenesis via direct stimulation of AR in ECs [7] This suggestion was supported by the report that administration of the non-aromatisable AR agonist dihydrotestosterone (DHT) reversed impaired hindlimb reperfusion in castrated male mice [7]. In the in vivo experiments described by Sieveking et al [7], it was not possible to determine whether the increased angiogenesis and restored hindlimb reperfusion stimulated by DHT were mediated by AR in the vasculature

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Results

Conclusion