Decreased glucose-6-phosphate dehydrogenase activity along with oxidative stress affects visual contrast sensitivity in alcoholics Subhasish Pramanik a , Upasana Ganguly a , Vineet Kumar Khemka a, b , Anindita Banerjee a, b, * a Department of Biochemistry, Institute of Post Graduate Medical Education & Research, Kolkata, India b Department of Biochemistry, ICARE Institute of Medical Sciences & Research, Haldia, India article info Article history: Received 26 October 2017 Received in revised form 15 February 2018 Accepted 16 March 2018 Keywords: Alcoholism Visual contrast sensitivity G6PD MDA Oxidative stress Visual dysfunction abstract Objective: To evaluate oxidative stress and glucose-6-phosphate dehydrogenase (G6PD) status of alco- holics and discern their association, if any, with visual contrast sensitivity function. Methods: Forty male alcoholic subjects and 36 male non-alcoholic subjects with the same age and nutritional status were enrolled in this study. Serum malondialdehyde (MDA) level and glucose-6- phosphate dehydrogenase (G6PD) activity of erythrocytes were determined by spectrophotometric assay. Contrast sensitivity (CS) function of study subjects was measured using the Rabin Contrast Sensitivity Test (Precision Vision ® , La Salle, Illinois, United States). Results: Serum MDA levels were significantly higher (p < 0.0001) and erythrocyte G6PD activity was significantly lower (p ¼ 0.0026) in alcoholic subjects compared to the controls. CS scores of both eyes were also found to be decreased significantly in alcoholic subjects (both at p < 0.0001) compared to control subjects. On the other hand, CS scores of the alcoholic subjects were inversely correlated with the serum MDA level (r ¼À0.746, p < 0.0001) and directly correlated with erythrocyte G6PD activity (r ¼ 0.78, p < 0.0001). A strong inverse correlation (r ¼À0.84, p < 0.0001) was also observed between serum MDA level and erythrocyte G6PD activity of alcoholic subjects. Conclusion: Reduced G6PD activity and increased serum MDA level might be the key cause of the early visual abnormalities, such as reduced CS function of the alcoholic subjects. © 2018 Elsevier Inc. All rights reserved. Introduction Alcohol consumption is a worldwide problem leading to both physical and psychological dependence. The definition of alco- holism is chronic alcohol use to such a degree that it interferes with physical as well as mental health, or with normal social behavior; alcoholism is a leading cause of mortality and morbidity (National Institute on Alcohol Abuse and Alcoholism, 2013). Alcohol con- sumption has been in existence in India for many centuries. Recent epidemiological studies indicate a rise in alcohol consumption among the Indian population from 3.6 L per capita from 2003 to 2005 to 4.3 L per capita from 2008 to 2010 (World Health Organization, 2010, 2014), with 11% of Indians being binge drinkers, compared to the global average of 16%. Alcohol consumption has been attributed to be a major risk factor for several chronic diseases and conditions such as liver disease, car- diovascular disease, diabetes, neuropsychiatric disorders, and certain cancers (World Health Organization, 2010). The risk of alcohol dependence begins with low levels of drinking and in- creases with both the volume and pattern of alcohol consumption on a particular occasion, to the point of intoxication, called “binge drinking”. Young adults are particularly at risk of engaging in binge drinking. The mechanisms underlying alcohol-induced cell death and disease are varied, but recent studies indicate that reactive oxygen species (ROS) may play an important role in this process. Excess levels of ROS can lead to DNA damage, lipid peroxidation, and protein modification (Wu, Zhai, & Shi, 2006). Lipid peroxidation products such as MDA may potentially alter membrane properties, including ion transport, deformability, membrane-bound enzyme activity, and aggregation states of the cell surface determinants (Cheeseman & Slater, 1993). G6PD, an enzyme of the hexose * Corresponding author. Department of Biochemistry, ICARE Institute of Medical Sciences and Research, Haldia, 721645, India. Fax: þ91 322 426 9261. E-mail address: anny.banerjee@gmail.com (A. Banerjee). Contents lists available at ScienceDirect Alcohol journal homepage: http://www.alcoholjournal.org/ https://doi.org/10.1016/j.alcohol.2018.03.007 0741-8329/© 2018 Elsevier Inc. All rights reserved. Alcohol 73 (2018) 17e24