Fig. 1.

Morphine increases HDAC2 expression in VTA DA neurons. A: examples of brain sections stained with antibodies to TH (green), HDAC2 (red), and DAPI (blue) with merged panels, which show the expression of HDAC2 in TH neurons in the VTA of saline (top)- and morphine (bottom)-treated rats. Scale bar, 20 μm. B: averaged levels of nuclear and somatic HDAC2 expression at 3 AP levels from saline- and morphine-treated rats. In this and all subsequent figures, numbers in parentheses indicate the number of animals examined. *Statistical significance.