The glutathione system in bone tissue under the action of copper-zinc ore components and antioxidants administration

Aim. To study changes in the glutathione system in bone tissue during chronic intoxication with elements contained in copper-zinc pyrite ore and antioxidant vitamin administration. Methods. 36 mature male white rats were divided into three groups (control, comparison, experimental). The rats of the experimental and comparison groups received intragastrically copper-zinc pyrite ore powder in a 2% starch solution as a suspension at a dosage of 60 mg/100 g bodyweight daily for three months. During the last month, the experimental group received an antioxidant vitamin preparation (the complex of vitamins with a trace element) containing α-tocopherol, β-carotene, ascorbic acid and selenium. The content of reduced glutathione, free thiol groups in proteins, the activity of glutathione peroxidase, glutathione transferase, glutathione reductase, gamma-glutamyl transferase, and glucose-6-phosphate dehydrogenase were determined in homogenates derived from femoral epiphysis. The statistical analysis of the results was performed using Statistica 6.0 software. The median (Me) and percentiles (Q1 and Q2) were calculated, a non-parametric Mann–Whitney U test was carried out to compare study groups. Results. Chronic intoxication with elements contained in copper-zinc pyrite ore causes impairment of the glutathione system in bone tissue. Intoxicated rats showed a decrease in the reduced glutathione content to 71.9% (р=0.014) and free sulfhydryl groups of proteins to 77.8% (р=0.0143), inhibition of glutathione-dependent antioxidant enzymes activities, and disruption of the glutathione reduction system in tissues, compared to the control group. Antioxidant vitamin administration increased the levels of reduced glutathione and free thiol groups of proteins, activated the enzymes involved in the glutathione system: the reduced glutathione content increased to 94.8% (p=0.2132), glutathione peroxidase activity to 85.7% (p=0.0432), glutathione transferase — up to 94.3% (p=0.5251), glutathione reductase — up to 86.1% (p=0.0442) compared to the control group. Conclusion. Chronic intoxication with metals contained in copper-zinc pyrite ore leads to decreasing the content of reduced glutathione and free thiol groups of proteins in bones along with reducing glutathione reductase and glucose-6-phosphate dehydrogenase activities, inhibition of glutathione peroxidase and glutathione transferase; an antioxidant vitamin administration increases the activity of glutathione reduction enzymes in bone tissue, the content of reduced glutathione and free sulfhydryl groups of proteins, the activities of glutathione peroxidase and glutathione transferase.