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. 2008 Oct 22;105(43):16773–16778. doi: 10.1073/pnas.0801793105

Fig. 1.

Fig. 1.

Activation of P2X7Rs in satellite cells down-regulates P2X3R expression in neurons. (A) Immunocytochemical analyses of P2X7R and P2X3R expression in DRGs. P2X7Rs (labeled green) were found only in GFAP-labeled (red) satellite cells, but not in NeuN-labeled (red) neurons. P2X3Rs (labeled red) were found only in DRG neurons, not co-localized with P2X7Rs. (B) Western analysis showed that blocking satellite glial cells with the glia Kreb cycle inhibitor FC significantly increased P2X3R expression in DRGs (FC/control = 1.52 ± 0.18, n = 3, *P < 0.05). (C) After blocking P2X7R activity with oxATP, P2X3R expression was significantly higher (P2X3: oxATP/control = 1.59 ± 0.10, n = 8, *P < 0.05), whereas P2X2R expression was unchanged (P2X2: oxATP/control = 0.90 ± 0.18, n = 3; P > 0.05). (D) Down-regulating P2X7Rs with P2X7-siRNA (P2X7: P2X7-siRNA/control siRNA = 0.58 ± 0.04, n = 4, *P < 0.05) resulted in an increase in P2X3R expression (P2X3: P2X7-siRNA/control siRNA 1.65 ± 0.23, n = 5, *P < 0.05). (E) P2X3 mRNA did not change after treatment with P2X7-siRNA (control siRNA: 1.08 ± 0.12, n = 5; P2X7-siRNA: 1.00 ± 0.18, n = 7, P > 0.05) or oxATP (control 1.00 ± 0.01, n = 4; oxATP: 0.95 ± 0.08, n = 6, P > 0.05). (F) A schematic showing the inhibitory control of P2X3R expression by P2X7Rs.