The effects of i.c.v. administration of NPFF and related peptides on the central antinociception of U69593 (i.c.v.) in mouse tail-flick test.

<p>(A) Dose-related effects of NPFF (3, 10 and 15 nmol) on the central antinociception of U69593. (B) Co-administrated RF9 (15 nmol, i.c.v.) antagonized the modulatory effects of NPFF (15 nmol, i.c.v.) on the central antinociception of U69593 (i.c.v.). (C) The effects of NPVF and dNPA on the central antinociception of U69593. Each value represents mean ± S.E.M. (n = 7–8 mice/group). ***P<0.001 indicating significant differences compared to Saline + U69593-injected group; ^###P<0.001 indicating significant differences from the modulatory effects of NPFF in the absence of RF9.