Figure 4.

Effects of nicotine and LY379268 on functional coupling of mGlu2/3 receptors to G-proteins. Stimulation of [³⁵S]GTPγS binding by the mGlu2/3 receptor agonist LY354740 was significantly decreased in rats self-administering nicotine compared with animals responding for food, suggesting mGlu2/3 receptor downregulation in all assessed brain areas (LY354740 × reward interactions; ^#p < 0.05, ^###p < 0.001; *p < 0.05, **p < 0.01, ***p < 0.001, different from food). Repeated LY379268 administration also decreased [³⁵S]GTPγS binding in the prefrontal cortex and increased [³⁵S]GTPγS binding in the nucleus accumbens and amygdala (LY354740 × LY379268 interactions, ^†p < 0.05, ^†††p < 0.001; ⁺p < 0.05, ⁺⁺p < 0.01, ⁺⁺⁺p < 0.001, different from food). Data represent mean ± SEM; n = 6.