Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 56 9 2018 12 25 559 562 EN Khadijeh Najafi Pharmacy Student Research Committee, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran. Daniel Elieh Ali Komi Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. AND Department of Immunology, Tabriz University of Medical Sciences, Tabriz, Iran. Habibolah Khazaie Sleep Disorders Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. AND Substance Abuse Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. Ali Moini Department of Internal Medicine, Imam Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran. Asad Vaisi-Raygani Department of Biochemistry, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran. Hamid Reza Ahmadi Substance Abuse Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. Mohammad Rasoul Ghadami Sleep Disorders Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. Amir Kiani Department of Pharmacology and Toxicology, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran. AND Regenerative Medicine Research Center (RMRC), Kermanshah University of Medical Sciences, Kermanshah, Iran. 2018 07 17 2018 10 28 Matrix metalloproteinases (MMPs) are a group of zinc-dependent proteolytic enzymes that play a role in extracellular matrix (mainly collagen) degradation and remodeling. MMPs are not only causes of the increase rewarding effects of drugs, but also act as pro-addictive agents. In this research, 22 morphine and 20 methamphetamine-dependent patients included and their serum levels and activity of MMP2 and 9 were assessed by ELISA and gelatin zymography and compared with those of 23 healthy individuals as a control group. Our findings showed a significant increase in serum levels and activity of MMP-2 in opium and methamphetamine groups in comparison with the control group. Moreover, unlike MMP-2, serum levels and activity of MMP-9 in both case groups found to be decreased. This study showed that long-term abuse of opium and methamphetamine changes the activity and serum levels of MMP9 and MMP2. The effects of methamphetamines and opium are associated with an increase in extracellular dopamine levels in the brain, achieved by facilitating the release of dopamine from pre-synaptic nerves. Our findings showed that serum levels and activities of MMP-9 and MMP-2 could be considered as alternative valuable biomarkers from those investigated of pro-addictive or anti-addictive factors in dependent patients. https://acta.tums.ac.ir/index.php/acta/article/view/7396 https://acta.tums.ac.ir/index.php/acta/article/download/7396/5153