3.4. Effect of α-aminovalerophenone derivatives on CPP
The CPP paradigm was used to study the rewarding effect of five α-aminovalerophenone derivatives. The percentages of time spent in both compartments during the preconditioning phase of all five experiments performed were around 50% (with no statistical differences found between compartments), indicating a total lack of preference for either compartment. Seven animals were withdrawn from the experiments due to an initial preference for one of the compartments (>70% of the total session time). Figure 3 shows the effects of α-aminovalerophenone derivatives on CPP paradigm. On the test day, one-way ANOVA revealed a significant effect of dose for all the compounds tested ([pentedrone], (F(3.51)=8.819); [N-ethyl-pentedrone], (F(3.49)=5.044); [N,N-diethyl-pentedrone], (F(3.49)=2.802); [α-PVP], (F(3.52)=4.555); [α-PpVP], (F(3.52)=4.179)).
Particularly, animals conditioned with pentedrone and α-PVP at 3 and 10 mg kg-1 showed a significant increase in the preference score compared with the saline-treated animals (See Figure 3A and 3D). Moreover, a significant increase in the preference score after N-ethyl-pentedrone repeated administrations was observed for all doses tested (1, 3 and 10 mg kg-1) compared to the control group (See Figure 3B). Post hoc analysis also confirmed a significant increase in the preference score compared to the control group, after N,N-diethyl-pentedrone administrations, but only at a dose of 12.5 mg kg-1 (See Figure 3C). Finally, after conditioning with α-PpVP, post hoc analysis only revealed an increase in the preference score at the lowest dose tested (7.5 mg kg-1) (See Figure 3E).