Fig. 2

Antinociceptive effects of the i.c.v. CRF-R1 agonist stressin I or CRF-R2 agonist Ucn-2 and their antagonism by the respective CRF-R1 (NBI 27914) or CRF-R2 (K41498) selective antagonists. The effects of i.c.v. CRF-R1 (stressin I) or CRF-R2 (Ucn-2) agonists on nociceptive paw pressure thresholds were measured by algesiometry. A i.c.v. administration of the CRF-R1 agonist stressin I significantly increased nociceptive thresholds in a dose-dependent manner (F_{(4, 25)} = 552.4; P < 0.001). B i.c.v. administration of the CRF-R2 agonist Ucn-2 significantly increased nociceptive thresholds (F_{(4, 25)} = 389.1; P < 0.001). C Dose-dependent antagonism of i.c.v. CRF-R1 agonist’s antinociception by co-administered CRF-R1 antagonist NBI 27914 (F_{(4, 25)} = 73.9; P < 0.001, one-way ANOVA and Dunnett’s test). D) Dose-dependent antagonism of i.c.v. Ucn-2 antinociception by co-administered CRF-R2 antagonist K41498 was significant (F_{(5, 30)} = 88.4; P < 0.001), *indicates significant differences from vehicle treatment; data points (n = 6) represent means ± SD