Age-related alterations in histone deacetylase expression in Purkinje neurons of ethanol-fed rats

Ethanol and age-induced pathologies of the Purkinje neuron (PN) may result from histone deacetylases (HDACs), enzymes which repress transcription through coiling of the DNA. The purposes of this study were to investigate expression patterns of Class 1 and IIa HDACs in PN and the effects of aging and alcohol on the density of HDACs and histone acetylation in PN. Ninety, eight month old rats (30/diet) were fed a liquid ethanol, liquid control, or rat chow diet for 10, 20, or 40 weeks (30/treatment duration). Double immunocytochemical labeling on tissue sections from these rats used antibodies against HDAC isoforms or acetylated histones, and calbindin, a marker for PN. Fluorescent intensities were also measured. Results showed a significant age but not an alcohol-related decrease in the densities of HDACs 2, 3, and 7. In contrast, there were age related-increases in the densities of phosphorylated form of HDAC (4, 5, 7) PN and in PN nuclei expressing HDAC 7. There were also a trend towards ethanol-induced inhibition of acetylation as the density of AH2b PN nuclei and AH3 and AH2b fluorescent intensity was significantly lower in the EF compared to the PF rats. This study presents unique data concerning which HDACs are commonly expressed in PN and indicates that aging rather than lengthy alcohol expression alters expression of the HDACs studied here. These results also suggest that lengthy ethanol consumption may inhibit histone deacetylation in PN.