Induction of TAC1 by capsaicin does not occur in all TRPV1 expressing cells. fluorescent immunohistochemical analysis of 10 μm sections from mouse neonate DRG explants with (iii and iv) anti-TRPV1 and (v and vi) anti-SP antibody (i, iii, v) before and (ii, iv, vi) after 24 hours incubation with 10 μM capsaicin. Ai and ii represent merged images showing cellular co-localisation of TRPV1 and SP (yellow). White arrow heads highlight cells that express SP but not TRPV1 after capsaicin treatment. B, and C, graphical analysis of the size distribution (in microns) of neurones within DRG explants expressing (B) SP and (C) TRPV1 before (White bar) and after (black bar) capsaicin treatment (n = 3, total number SP/TRPV1 immunostaining cells counted and measured = 284, *; p < 0.05).