Figure 4.

Blockade of hippocampal D₁-like receptor, not D₂-like receptor, prevents the antidepressant effects of 6-Chloro-7,8-dihydroxy-3-methyl-1-(3-methylphenyl)- 2,3, 4,5-tetrahydro-1H-3-benzazepine (SKF83959). (A) Mice were daily pretreated with the antagonist of D₁-like receptor (7-chloro-3-methyl-1-phenyl-1,2,4,5- tetrahydro-3-benzazepin-8-ol [SCH23390]) or D₂-like receptor (raclopride) for 3 days before SKF83959 (1mg/kg, i.p.) administration, respectively. Pretreatment with SCH23390, not raclopride, prevented the SKF83959-induced decrease in immobility duration in the forced swim test (FST) test (n=10). (B) CSDS-treated mice were co-injected with SKF83959 and SCH23390/raclopride for 14 days. Administration of SCH23390, not raclopride, blocked the behavioral effects of SKF83959 in the sucrose preference test (n=10). (C) Administration of SCH23390, not raclopride, blocked the behavioral effects of SKF83959 in the social interaction test (n=10). (D) The effects of SKF83959 on hippocampal brain-derived neurotrophic factor (BDNF) expression were blocked by SCH23390, not raclopride (n=5). (E) The effects of SKF83959 on hippocampal pCREB level were also abolished by SCH23390, not raclopride (n=5). Data are expressed as means ±SEM; ^## P <.01 vs control; ** P<.01 vs defeated + vehicle group. Comparison was made by 2-way analysis of variance (ANOVA) followed by posthoc Bonferroni’s test.