**2.4. Epigenetic mechanism**

It is an efficient mechanism for gene regulation by altering the packaging of DNA within chromatin through interactions with histones. CREB requires phosphorylation to initiate transcription of pro-survival neuronal factors (**Figure 2**). A study revealed an increase in CREB (a regulator for plasticity of neurons), increase in H3-H4 (a central histone tetramer) acetylation and inhibition of HDAC (histone deacetylases) activity in a rat amygdala when given an acute dose of ethanol for 15 days. A trichostatin (HDAC inhibitor) was used to treat the rats, resulting in deacetylation of H3-H4, CREB inhibition, reduced NPY expression and HDAC activation in the rat amygdala [57].

**Figure 2.** Epigenetic modifications associated with alcoholism.
