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. Author manuscript; available in PMC: 2014 Dec 3.
Published in final edited form as: Biol Psychiatry. 2013 Dec 5;76(10):823–831. doi: 10.1016/j.biopsych.2013.11.023

Figure 5.

Figure 5

(A) There were no significant differences between mice carrying either single transgene, tetracy-cline transactivator (tTA) (calcium/calmodulin-dependent kinase IIα-tTA), tet-operator (tetO) (tetO-dopamine D3 receptor), or no transgene (wild-type [WT]) in lever pressing in the progressive ratio (PR × 2) task. (B) Male mice with an overexpression of dopamine D3 receptors (D3R-OE mice) made significantly fewer lever presses in the task compared with the control groups combined (*p < .042). (C) Single transgenes also had no effect on the number of rewards earned. (D) Male D3R-OE mice earned significantly fewer rewards compared with the control groups combined (*p < .014). (E) Switching off the D3R-OE transgene in adult mice was sufficient to rescue the deficit in lever pressing in the PR × 2 test for motivation. (F) Doxycycline (DOX) also rescued the number of rewards earned in the task. CHOW, regular homecage chow diet (Non-DOX).