Figure 4. Abstinence from chronic intermittent ethanol exposure augments the phosphorylation of CaMKII α in the dorsal medial prefrontal cortex, an effect that is associated with inflexible performance.

Total and phosphorylated levels of CaMKIIα (threonine 286) were estimated from microdissections of the medial prefrontal cortex (mPFC) in ethanol-naïve controls (CON, n=6) or rats that were re-exposed to ethanol vapor and abstinence procedures (EtOH, n=7) from the behavioral studies. The mPFC wet tissue slice (A) was dissected for regions comprising the dorsal (i.e., primarily prelimbic cortex) or ventral mPFC (i.e., primarily infralimbic cortex). Fluorescence values of immunoreactivity for total and phosphorylated CaMKIIα relative to the loading control glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were analyzed as a percentage change from CON levels (mean ± SEM) across brain regions (B and C). Representative images for each group illustrate the gel band and molecular weight of the proteins quantified in the analysis. Whereas total CaMKIIα levels remained comparable across groups and brain regions, EtOH rats undergoing 10 days of abstinence displayed an increase in phospho-CaMKIIα levels in the dorsal (B) but not ventral (C) mPFC as compared to CON. To gain insight on the role of upregulated phospho-CaMKIIα, we correlated these measures with respective performance during the set-shift (D, E, and F) in CON (open circles) and EtOH (closed circles) rats. Phospho-CaMKIIα in the dorsal mPFC correlated with inflexible performance, showing a positive association with increasing total errors (D), as well as indices of perseverative-like responding via previously-reinforced (E), but not never-reinforced (F) errors. An asterisk (*) denotes significant group differences (p<0.05).