Cyanide-induced hyperthyroidism in male Wistar rats

BACKGROUND: Cyanide is one of the major environmental pollutants termed thyroid disruptor. Regardless of its origin, it is a primary toxic agent. This study was designed to understand the impact of prolonged low dose cyanide exposure on the structure and function of the thyroid gland. MATERIALS AND METHODS: Twelve F1 male Wistar rats were used for this study. They were divided into two groups of six animals each. The first group served as the control group and received 0.25M sucrose while the second group being the treated group received 2 mg/kg body weight (BW) potassium hexacyanoferrate III solution. The treatment duration was 56 days following which the animals were sacrificed by cervical dislocation. Blood samples were drawn to determine serum FT3, FT4 and thyroid stimulating hormone (TSH) levels. The thyroid gland was also excised and processed for light microscopic studies. RESULT: An increase in serum FT3 and FT4 with decrease serum TSH was obtained in the treated group. Application of one-way analysis of variance (ANOVA) statistical analysis showed that there were highly significant differences (P < 0.05) in the activities of FT3, FT4 and TSH when compared with those of the control group. Light microscopic examination of thyroid gland from the treated group revealed marked epithelial hyperplasia with cellular degeneration and scanty cytoplasm while the control group revealed normal thyroid architecture. CONCLUSION: Results obtained revealed that hyperthyroidism was induced by cyanide.