Acute Low Dose Oral Cyanide Induced Thyrotoxic State by Oxidative Stress in Rats

This study assessed the cyanide induced thyrotoxic state by oxidative stress on the thyroid gland. Twelve (12) first filial (F1) generation in bred adult male Wistar rats were randomly and equally divided into two groups. Group I received 0.25M sucrose while Group II received 20mg/KgBW of potassium hexacyanoferrate III solution both for the duration of 14 days. Animals were sacrificed by chloroform ether anesthesia, blood samples collected to determine the serum Free Tri-iodothyronine (FT3), Free Tetra-iodothyronine (FT4) and Thyroid Stimulating Hormone (TSH) concentration and thyroid gland excised and processed for light microscopic examination and histomorphometry while the activities of Malondialdehyde (MDA) and Superoxide dismutase (SOD) were assayed from the thyroid tissue homogenates. Light microscopic examination of the thyroid gland from the treated group showed enlarged hyperplastic thyroid follicle lined by degenerated columnar follicular cells while the control group showed normal thyroid follicle architecture. Maximum diameters of the follicles from the slides of thyroid tissues of both groups of animals were measured and data acquired were analyzed using Image J software and student's T-test. The result obtained showed a highly significant difference in the diameters of follicles of the two groups of animals on comparism. Increased activities of MDA and SOD with increased serum FT3 and FT4 and decreased serum TSH concentrations were observed in the treated group. Results obtained from MDA, SOD, FT3, FT4 and TSH activities were highly significant (P?0.05) on application of one-way ANOVA statistical analysis when compared with those of their control. The study showed that acute cyanide exposure effectively induced thyrotoxic state by oxidative stress.

Key Words: Cyanide, thyroid hormones, thyrotoxic state, oxidative stress