We investigated the acute effects of glucagon-like peptides-1 (GLP-1), GLP-1(1-36) and GLP-1(7-36) on vascular endothelial growth factor-A (VEGFA)-induced endothelium-dependent signaling and vasodilation. Our hypothesis was that GLP-1 released from intestinal L-cells modulates processes related to PLCγ activation, Src and eNOS signaling, thereby controlling endothelial vessel tone. By using RT-PCR we found mRNA for the GLP-1 receptor (GLP-1R) in human dermal microvascular endothelial cells (HDMEC), human retinal microvascular endothelial cells (HRMEC) and rat arteries. In isolated rat mesenteric resistance arteries precontracted with the thromboxane analogue U46619 to 80-90% of maximum contraction, VEGFA (25 ng/ml) caused a small and gradual relaxation (28.9±3.9%). Pretreatment of arteries with either GLP-1(1-36) (500 nM) or GLP-1(7-36) (1 nM) abolished the VEGFA-induced relaxation. VEGFA-induced relaxations were also inhibited in endothelial denuded arteries and in arteries pretreated with the nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester (100 μM). In vivo studies on male Wistar rats also revealed that GLP-1(7-36) inhibited VEGFA-induced vasodilation of the same arteries. In isolated endothelial cells, GLP-1(1-36) and GLP-1(7-36) caused a reduction in VEGFA-induced phosphorylation of PLCγ. Ca2+ imaging of endothelial cells and rat mesenteric resistance arteries using fura-2, revealed that both GLP-1 analogues caused a reduction in VEGFA-induced Ca2+ signaling. GLP-1(1-36) also reduced VEGFA-induced eNOS phosphorylation in HDMEC. In conclusion, GLP-1 reduced relaxation induced by VEGFA in resistance arteries by inhibiting VEGFR2-mediated Ca2+ signaling and endothelial nitric oxide synthesis. GLP-1, on its own, also induced phosphorylation of Src and ERK1/2 that can lead to proliferation and is implicated in vessel permeability.
- VEGFA signaling
- endothelial cells
- PLCγ and eNOS
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology