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. 2014 Jan 28;8:5. doi: 10.3389/fnins.2014.00005

Figure 5.

Figure 5

Antidepressant-like effect of almorexant on DRL-72-s responding in rats and DRL-36-s responding in mice. (A) dose-dependent increase in the number of reinforcers obtained by male SD rats in DRL-72-s, with significant effects at 100 mg/kg (p < 0.05), as well as a lack of effect of the inactive enantiomer at 100 mg/kg (n = 11); (B) dose-dependent and significant increase in the number of reinforcers obtained (p < 0.05) by C57Bl/6 mice in DRL-36-s at 100 mg/kg and a significant decrease (p < 0.05) in total responses emitted at 100 mg/kg, as well as lack of effect of the inactive enantiomer at 100 mg/kg (n = 8); (C) significant decrease in responses emitted at all doses tested (p < 0.05) with a concomitant increase in reinforcers received at doses of 10 and 40 mg/kg (p < 0.05) in mice lacking OX1 receptors (n = 8). However, 100 mg/kg of the inactive enantiomer also produced significantly fewer responses (p < 0.05) with a concomitant increase in reinforcers received (p < 0.05) in mice lacking OX1 receptors; (D) almorexant failed to produce antidepressant-like effects in mice lacking OX2 receptors, up to 100 mg/kg (n = 8). The inactive enantiomer (100 mg/kg) significantly reduced total responses emitted in mice lacking OX2 receptors (p < 0.05), without significantly affecting reinforcers earned (n = 8). *p < 0.05 vs. respective vehicle, Dunnett's post-hoc analyses.