Fig. 2

The effects of the administration of saline, as a vehicle, and different doses of S-3,4-DCPG, as a potent and selective mGlu8 agonist, (0.03, 0.3 and 3 μg/0.5 μL) into the nucleus accumbens (NAc), 5 min before the injection of morphine (5 mg/kg, SC) and administration of maximum dose of S-3,4-DCPG into the NAc region alone, in the conditioning days. Saline group received SC injection of saline instead of morphine during the acquisition phase. Bars represent mean ± S.E.M (Pre-conditioning; n = 8, Saline; n = 6, Vehicle; n = 7, different doses of S-3,4-DCPG (0.03 μg/0.5 μL; n = 10, 0.3 μg/0.5 μL; n = 10 and 3 μg/0.5 μL; n = 9 μg/0.5 μL). *P < 0.05, ***P < 0.001, Kruskal Wallis test followed by Dunn's multiple comparisons test