Figure 2.

Prefrontal in situ hybridization point to the infralimbic cortex as major site of neuroadaptations. A, Dark-field microphotographs from autoradiograms of in situ hybridization of Grm2 from control and postdependent (PD) rats on coronal sections, +2.2 mm relative to bregma level. Enlarged images for both groups on the right. Arrows indicate signal in the infralimbic region. B, Quantification of in situ expression levels (nanocuries per gram, mean ± SEM) in postdependent (black bars) versus control rats (white bars) for selected candidate genes significantly altered. Nr-2a, Nr-2b, Egr1, and Grm2 mRNAs are robustly altered within the infralimbic cortex, but unaffected in cingulate, prelimbic, or orbitofrontal cortex. *p < 0.05; **p < 0.01; ***p < 0.001 comparing postdependent versus control (Student's t test). Cing, Cingulate cortex; PreL, prelimbic cortex; IL, infralimbic cortex; OFC, orbitofrontal cortex.