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. Author manuscript; available in PMC: 2009 Aug 1.
Published in final edited form as: Neuropharmacology. 2008 May 22;55(2):215–222. doi: 10.1016/j.neuropharm.2008.05.011

Fig. 4.

Fig. 4

The dose-response effect of intrathecal injection of the δ-opioid agonist DPDPE on the nociceptive withdrawal threshold in vehicle- and RTX-treated rats. A: time course of the effect of intrathecal injection of 5 (n = 6), and 10 (n = 7), and 20 µg (n = 7) DPDPE on the nociceptive withdrawal threshold in the vehicle-treated rats. B: time course of the effect of intrathecal injection of 5 (n = 7), and 10 (n = 7), and 20 µg (n = 8) DPDPE on the nociceptive threshold in RTX-treated rats. Note that intrathecal injection of 20 µg DPDPE failed to alter significantly the withdrawal threshold in the presence of 25 ìg naltrindole (n = 7). The nociceptive threshold was assessed by testing the withdrawal response of the hindpaw to a noxious pressure stimulus. Data are presented as means ± SEM. *, P < 0.05 compared with the respective baseline control. NLT, naltrindole.