134 | Histone Methyltransferases Plays a Fundamental role on Nicotine Preference in Zebrafish

Cognition, Behavior, and Memory

Author: Joaquin Ortiz | Email: joaquinortiz22.jo@gmail.com

Joaquin Ortiz , Leandro Rocco , Maria Paula Faillace , Ramon Bernabeu


Psychostimulants regulate behavioral responses in zebrafish via epigenetic mechanisms. We have previously shown that DNA methylation and histone acetylation inhibition abolish nicotine-induced conditioned place preference (CPP) but little is known about the role of histone methylation in addictive-like behaviors. To assess the influence of histone methylation on nicotine-CPP, zebrafish were treated with a histone 3 (H3) lysine-9 (K9) dimethyltransferase G9a/GLP inhibitor, BIX-01294 (BIX), which was administered before conditioning sessions. We observed a dual effect of the inhibitor BIX: at high doses inhibited while at low doses potentiated nicotine reward. Transcriptional expression of ?6 and ?7subunits of the nicotinic acetylcholine receptor and of G9a, DNA methyl transferase-3, and HDAC-1 were upregulated in zebrafish with positive scores for nicotine-CPP. BIX treatment per sé did not affect transcriptional levels of epigenetic enzymes that regulate trimethylation or demethylation of H3. BIX reduced H3K9me2 protein levels in a dose-dependent manner in key structures of the reward pathway. Our data demonstrate that H3 methylation catalyzed by G9a/GLP is involved in nicotine-CPP induction. Dimethylation of K9 at H3 is an important epigenetic modification that should be considered as a potential therapeutic target to treat nicotine reward and perhaps other drug addictions.