Dopamine receptor 3 (D3) knockout mice show regular emotional behaviour

The "Dopamine Deficiency Hypothesis" and a considerable number of recent pharmacological studies propose to thoroughly verify and improve the standard of knowledge regarding a possible role of dopamine in the pathogenesis and treatment of depression. To elucidate the potential role of D3 receptors in the development of a depressive-like phenotype, we subjected D3 receptor knockout mice to a series of selected behavioural paradigms particularly focussing on depressive-like traits. In our experimental design we exposed animals with a deficiency of the D3 receptor (D3-/-) to a standardised behavioural test battery, in which general changes of locomotion, exploration, anxiety and depressive-like characteristics (i.e. Learned Helplessness, Sucrose Consumption and Forced Swim test) can be detected. Thorough behavioural phenotyping, however, neither revealed behavioural consequences on the basal level (locomotion, exploration) nor depressive- or anxiety-like alterations. Hence, these results do not indicate an evident involvement of the D3 receptor in the development of a depression-like syndrome in mice for now. This does, however, not exclude the D3 receptor as a potential target for pharmacotherapy.