Assessment of mitochondrial DNA copy number in peripheral blood leukocyte of opiate abusers and healthy individuals

Background: Based on the studies, variation in the mitochondrial DNA (mtDNA) copy number in peripheral blood leukocytes is associated with increased susceptibility to diseases including cancer. Opiate abusers are at high risk for diseases. In this study, we measured the mtDNA copy number in peripheral blood leukocytes in a group of opiate abusers compared with those in healthy individuals. Methods: In a case/control study, three groups were selected consisting of 32 opium abusers, 24 heroin addicts and 25 healthy individuals. The amount of 5 ml of whole blood was collected from each individual who participated in the study and stored at -20 centigrade. The sample collection was performed from November 2018 to February 2020. Case groups were recruited from the Methadone maintenance therapy center. Contro group had no history of drug use and cigarette smoking. DNA was extracted from the whole blood samples using the salting out method. The DNA from a mitochondrial gene, dehydrogenase subunit1 (-ND1 gene) and a nuclear gene, human globulin (HGB gene), were quantified by a real-time PCR-based method to measure the relative mtDNA copy number of each group number. Results: There was no significant difference in demographic characterization between the three study groups, opium abusers, heroin addicts and healthy individuals. We found that opium users had a higher mean of mtDNA copy number than those in the healthy control group (P=0.11). Heroin addicts had also higher mean of mtDNA copy number than those in healthy group (P=0.21). The mean mtDNA copy number in opium abusers was higher than that in heroin addicts (P=0.22), although the difference was not statistically significant. Conclusion: The results of this study indicated that mtDNA copy number increased in a group of opiate abusers. Considering that alteration of mtDNA copy number is associated with increased susceptibility to several diseases including cancer, further research on mtDNA copy number with a high number of volunteers of opiate addicts may clear the effect of opiate abuse on the human genome.