Effect of D1- and D2-like Dopamine Receptor Antagonists on the Rewarding and Anxiolytic Effects of Neurotensin in the Ventral Pallidum

Figures

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  Figure 1. Illustration of correct bilateral injection placements of the injector tips (n = 145). The numbers on the left side of the coronal brain sections refer to anterior–posterior distance from the bregma in mm. The borders of VP are presented based on the stereotaxic rat brain atlas of Paxinos and Watson [38]. The circular symbols indicate the centre of the bilateral injection sites. Numbers next to the symbols indicate the number of animals with similar cannula positions.

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  Figure 2. Effects of D1-like DA receptor antagonist SCH23390 pretreatment on the NT induced conditioned place preference in the VP. Columns represent mean time spent in the treatment quadrant (±S.E.M.) during Habituation and Test trials, respectively. Control group: rats received two microinjections of vehicle (n = 7). NT group: animals microinjected with vehicle + 100 ng NT (n = 7). D1-like ant. group: animals received 1 µg SCH23390 + vehic1e (n = 8). D1-like ant. + NT group: effect of microinjections of 100 ng NT after 1 µg SCH23390 pretreatment (n = 9). For further explanation, refer to the text. *: p < 0.05.

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  Figure 3. Effects of D2-like DA receptor antagonist sulpiride pretreatment on the NT induced conditioned place preference in the VP. Columns represent mean time spent in the treatment quadrant (±S.E.M.) during Habituation and Test trials, respectively. Control group: rats received two microinjections of vehicle (n = 8). NT group: animals microinjected with vehicle + 100 ng NT (n = 7). D2-like ant. group: animals received 4 µg D2-like DA receptor antagonist sulpiride + vehic1e (n = 7). D2-like ant. + NT group: effect of microinjections of 100 ng NT after 4 µg sulpiride pretreatment (n = 8). For further explanation, refer to the text. *: p < 0.05.

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  Figure 4. Effects of D1-like DA receptor antagonist SCH23390 pretreatment on the anxiolytic effect of NT in the VP in EPM test. Columns represent mean time spent at the closed arms, time spent at the open arms, and time spent at the ends of the open arms, respectively (±S.E.M.). Control group: rats received two microinjections of vehicle (n = 11). NT group: animals microinjected with vehicle + 100 ng NT (n = 10). D1-like ant. group: animals received 1 µg SCH23390 + vehicle (n = 12). D1-like ant. + NT group: effect of microinjections of 100 ng NT after 1 µg SCH23390 pretreatment (n = 12). For further explanation, refer to the text. *: p < 0.05.

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  Figure 5. Effects of D2-like DA receptor antagonist sulpiride pretreatment on the anxiolytic effect of NT in the VP in EPM test. Columns represent mean time spent at the closed arms, time spent at the open arms, and time spent at the ends of the open arms, respectively (±S.E.M.). Control group: rats received two microinjections of vehicle (n = 11). NT group: animals microinjected with vehicle + 100 ng NT (n = 9). D2-like ant. group: animals received 4 µg D2-like DA receptor antagonist sulpiride + vehicle (n = 9). D2-like ant. + NT group: effect of microinjections of 100 ng NT after 4 µg sulpiride pretreatment (n = 10). For further explanation, refer to the text. *: p < 0.05.