Effects of acute organophosphate poisoning on thyroid hormones in rats

The aim of this study was to investigate the effects of organophosphate poisoning on thyroid hormones. In this study, male Wistar albino rats weighing 200-225 g were used. The rats were divided into 4 groups. Group 1 (n = 10) was administered 30 mg/kg lethal dose of methamidophos, whereas group 2 (n = 7) was treated with physiologic NaCl (SP). Group 3 (n = 10) was treated with 30 mg/kg of methamidophos. When cholinergic symptoms developed among the rats in group 3, they were treated with 40 mg/kg pralidoxime intraperitoneally (IP) and administered atropine IP until the cholinergic symptoms disappeared. Group 4 (n = 7) was treated with SP. After the cholinergic symptoms appeared among the rats in group 1, intracardiac blood samples were taken. In group 3, blood samples were taken after the cholinergic symptoms had disappeared. Then triiodothyronine (T3), thyroxine (T4), thyroid stimulating hormone (TSH), and plasma choline esterase (PCE) levels were studied by RIA. The Kruskal-Wallis test and Mann-Whitney U test were used for comparison between groups. Bonferroni correction was applied when multiple comparisons were made. T3, T4, and TSH levels decreased in group 1 compared with group 2 (P < 0.01). When the results between groups 3 and 4 were compared, it was found that the T3 and T4 levels in group 3 decreased while the decreases in T3 levels were statistically significant (P < 0.01). When comparing the results of groups 1 and 3, the T4 level was lower in group 1 and the T3 level was higher in group 3 (P < 0.01). The TSH level increased in group 3 after treatment (P < 0.01). Thyroid hormones were affected after acute organophosphate poisoning. Hypothyroidism and sick euthyroid syndrome was observed during poisoning and after treatment. In serious poisoning, there may be a poor prognosis, but more extensive studies will illuminate the issue in depth.