Dissertation
Dissertation > Medicine, health > Neurology and psychiatry > Psychiatry > Mental disorders of toxic > Alcohol disorder

The Changes of HTR3A Gene Histone H3K9Acetylation and Gene Expression in Alcohol-dependent Patients

Author WangLinLin
Tutor HaoWei
School Xinxiang Medical
Course Psychiatry and Mental Health
Keywords alcohol dependence HTR3A histone acetylation gene expression
CLC R749.62
Type Master's thesis
Year 2013
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BackgroundAlcohol dependence is a complex disease which is caused by interactions of multiple genetic and environmental factors. Current studies show that epigenetic modifications are involved in the pathological process of alcohol dependence, and the HTR3A receptor is involved in neurobiology pathway of alcohol dependence. Many studies have reported that HTR3A gene was involved in alcohol craving, alcoholism and addiction.Objective1. To explore the role of HTR3A gene epigenetic modification in the pathogenesis of alcohol dependence, the relative level and relationship of HTR3A gene histone H3K9acetylation and gene expression in alcohol dependence group were analyzed.2. To explore the relationship between epigenetic modification and clinical characters in alcohol dependence group, the relationship among severity and craving in alcohol dependence group and the levels of HTR3A gene histone H3K9acetylation and gene expression were analyzed.Methods1. Fifty patients with alcohol dependence were recruited in case group according to the standard of DSM-IV diagnosis.Thirty six healthy controls matched with case group on age, degree of education and region were recruited in control group. AUDIT (The Alcohol Use Disorders Identification Test) was used to assess the severity of alcohol dependence in two groups. After admission, the craving of alcohol-dependent patients was measured by OCDS (Obsessive Compulsive Drinking Scale). 2. DNA fragments were drawed on the base of ChIP kit instruction. The levels of histone H3K.9modifications in HTR3A and GAPDH gene promoter were measured by real-time PCR. The relative levels of HTR3A gene was calculated between case group and control group using the2-△△CT method. Different levels of histone H3K9acetylation were measured using two independent sample t-test between the two groups.3. The level of HTR3A gene expression was detected by reverse transcription Real-time PCR between case group and control group. Total RNA was extracted using Trizol reagent, processed, reverse-transcribed to cDNA by a first-strand synthesis kits, and quantified using Real-time PCR. The relative level of HTR3A mRNA was standardized by GAPDH, and the expression differences between two groups were compared using two independent samples t-test.4. The relationship of histone H3K9acetylation level in HTR3A gene promoter region and HTR3A mRNA expression level were analyzed by Pearson correlation analysis in the peripheral blood of alcohol-dependent patients.The relationships between severity or craving from alcohol-dependent patients and the levels of HTR3A gene histone H3K9acetylation and gene expression were measured respectively through Pearson correlation analysis method in case group.Results1.50cases and36healthy controls (all of them were male) from Xinxiang city and nearby areas were included in the study. The age difference between cases and controls was no significant (41.18±1.34for cases,41.40±1.70for controls,t=0.363, P=0.718). The mean OCDS total score, OCDS-os score and OCDS-cs score were22.36±0.77,9.30±0.37,13.10±0.44in case group. The average value of AUDIT was19.06±0.81(values greater than or equal to8as a positive).2. Compared with control group (1.00±0.00, n=36), the HTR3A gene promoter region histone H3K9acetylation level in case group (2.37±0.10, n=50) was significantly increased(t=12.033,P=0.000).The histone H3K9acetylation in housekeeping gene GAPDH (1.06±0.03, n=50) promoter region was no significant difference (t=1.748, P=0.084).3. The level of HTR3A gene expression in peripheral blood in case group (2.06±0.09, n=50) was significantly higher (t=10.155, P=0.000) than control group (1.00±0.00, n=36).4. The expression level of HTR3A gene was positively correlated (r=0.322,P=0.023) with H3K9acetylation level of HTR3A gene promoter region in case group.5. There were no correlation among OCDS total score, OCDS-os score, OCDS-cs score and the level of HTR3A gene histone H3K9acetylation (r=0.076, P=0.601, r=0.021, P=0.884, r=0.130, P=0.368). The level of HTR3A gene expression was positively correlated with OCDS total score (r=0.309, P=0.029), the level of HTR3A gene expression was positively correlated with OCDS-os score (r=0.290,P=0.041).The OCDS-cs score was positively correlation with the level of HTR3A gene expression (r=0.314, P=0.026).6. Alcohol severity scale AUDIT was no correlated with the level of HTR3A gene histone H3K9acetylation (r=0.277, P=0.052). Alcohol severity scale AUDIT was positively correlated with the expression level of HTR3A gene (r=0.307, P=0.030).Conclusion1. Histone H3K9acetylation in HTR3A gene promoter region promoting HTR3A gene expression may be one of the biological mechanisms of alcohol dependence.2. Increasing expression level of HTR3A gene is associated with craving and severity in alcohol-dependent patients.

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