Disc angiogenesis system: mecamylamine inhibits inflammatory angiogenesis in vivo. (a and b) Subcutaneous implantation of a polyvinyl sponge for 3 weeks resulted in ingrowth of new vessels (b is a detailed view of the tagged area in a). (c–e) The nAChR antagonist mecamylamine significantly decreased the vascularized area of the disc (c and e) and the vessel density in the disc (d, a detailed view of the tagged area in c). In contrast, treatment with the muscarinic acetylcholine receptor antagonist did not result in a significant reduction of neovascularization (e). *P < 0.01 vs. control. (f) Proliferating vessels in the disc stained positive for the α7-nAChR. A representative microscopic picture is shown. (g) In α7-nAChR–deficient mice, the angiogenic response was significantly reduced but the proangiogenic effect of nicotine was partially preserved. Results are shown as box plots displaying 25th and 75th percentiles as boxes and 5th and 95th percentiles as thin lines. n = 5; P < 0.01 compared with control mice.