ABSTRACT: Here, we examined mouse brain trancriptional changes 1 hour after the 10th daily i.p. treament with one of the four following treaments: i) vehicle control (45% saline, 45% PEG-400 and 10% DMSO administered at 7.5mL/kg), ii) Cpd-60, 45mg/kg , administered at 7.5mL/kg or iii) SAHA, 25mg/kg, administered at 5mL/kg) or iv) CI-994, 10mg/kg, administered at 5mL/kg. Cpd-60 is a benzamide HDAC inhibitor with selectivity for class I HDAC subtypes HDAC1 and HDAC2; CI-994 is a benzamide inhibitor with selectivity for HDACs1,2 and 3; SAHA is a hydroxamic acid HDAC inhibitor with selectivity for class I HDAC subtypes 1,2, and 3 and the class II HDAC subtype HDAC 6. We examined transcript differences using the Illumnia WG-6 2.0 whole genome expression array and profiled 3 specific brain regions (prefrontal cortex, nucleus accumbens, hippocampus) from each of 36 mice (n=6 mice / treatment group) . For application to array chips, we pooled two biological replicates from like treatment and brain region-groups such that 36 samples were applied in total: 4 treatment groups x 3 brain regions per treament group x 3 pools of two samples each for each treatment/brain region. Treatment groups: All adult male, C57BL/6 mice (n=6mice/treatment group) were sacrificed by rapid cervical dislocation and decapitation 1 hour after the tenth daily i.p. injection with one of the four following treaments: i) vehicle control (45% saline, 45% PEG-400 and 10% DMSO administered at 7.5mL/kg), ii) Cpd-60, 45mg/kg , administered at 7.5mL/kg or iii) SAHA, 25mg/kg, administered at 5mL/kg) or iv) CI-994, 10mg/kg, administered at 5mL/kg. Brains were removed, frozen immediately on dry ice and stored at -80°C until use. Frozen mouse brains (n = 6/ treatment group) were rapidly dissected at 4°C, isolating medial prefrontal cortex, nucleus accumbens and hippocampus. RNA was isolated using the Qiagen RNeasy Lipid Tissue mini kit, RNA concentration was determined using a NanoDrop spectrophotometer and quality was assessed using Agilent Bioanalyzer PICO chips, with the RNA Integrity Number (RIN) determined at 7.0-8.8 for all samples assayed, indicative of good RNA quality. For microarray experiments on Illumina MouseWG-6 BeadChips, RNA samples were pooled from two biological replicates such that the total number of samples was 36 (3 treatment groups x 3 brain regions x 3 RNA pools representing two mice per pool). All microarray analysis and gene set analysis (GSA) was performed using GeneSpring software (v.11.5.1) with raw signals adjusted using quantile normalization and baseline transformation with the median signal in all samples set to zero. Data were included in subsequent analyses if the normalized signal, thresholded at 0.8, was ‘present’ for 3 of 3 replicates for like treatment and tissue groups.
