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Granulosa cell apoptosis by impairing antioxidant defense system and cellular integrity in caprine antral follicles post malathion exposure

Bhardwaj, Jitender Kumar, Saraf, Priyanka
Environmental toxicology 2016 v.31 no.12 pp. 1944-1954
DNA fragmentation, acridine orange, antioxidant activity, antioxidants, apoptosis, catalase, chromatin, ethidium, fluorescence, goats, granulosa cells, histology, malathion, oxidative stress, reproduction, reproductive toxicology, staining, superoxide dismutase
Toxicological studies have demonstrated the exposure‐risk relationship of several pesticides on reproduction of living organisms. To evaluate the role of malathion as a reproductive toxicant, this study aims at assessing the cytological and biochemical changes in the granulosa cells after malathion exposure in dose (1 nM, 10 nM, 100 nM) and time (4 h, 6 h, 8 h) dependent manner. Histomorphological analysis, fluorescence assay, apoptosis quantification, and terminal deoxynucleotidyl transferase d‐UTP mediated nick end labeling (TUNEL) assay were done to determine cytological changes, whereas antioxidant enzyme assays were done to measure the oxidative stress in malathion treated ovarian antral follicles. Histological studies exhibited the occurrence of highly condensed or marginated chromatin with fragmented nucleus, pyknosis, loss of membrane integrity, increased empty spaces, and vacuolization in malathion treated granulosa cells. Ethidium bromide/acridine orange (EB/AO) fluorescence staining demonstrated a significant increase in incidence and percentage of apoptosis after malathion exposure (p < 0.001), both between and within the groups. Malathion exposure also resulted in increased DNA fragmentation and decline in both antioxidant enzymes activity namely catalase (CAT) and superoxide dismutase (SOD) in granulosa cells of antral follicles. Moreover, there was found a significant negative correlation between the apoptosis incidence and the level of antioxidant enzymes activity, SOD (r = −0.73 p < 0.01) and CAT (r = −0.80 p < 0.01), in malathion treated ovarian antral follicles. Thus, highlighting the role of DNA fragmentation and declining antioxidant level as a possible mechanism underlying malathion induced reproductive toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1944–1954, 2016.