RESUMEN
Aim: This study was aimed at understanding the earlier findings involving chronic, lowlevel cyanide exposure resulting from eating poorly processed cassava products associated with the development of goitre as seen in cassava endemic regions of Nigeria. Study Design: 30F1 female adult Wistar rats were divided into five (5) groups of 6 animals each. Groups 1 to 4 represented the treatment groups while group 5 was the control of the experiment. The cyanide treatment dose were; group1: 20mg/KgBW, group 2: 12mg/KgBW, group 3: 6mg/KgBW and group 4: 2mg/KgBW while the control group received 0.25M Sucrose. Place and Duration of Study: The animal facility of College of Health Sciences, Osun State University, Osogbo, Osun State, Nigeria. The treatment duration was 30days. Methodology: Animals were sacrificed by cervical dislocation. The blood samples were collected to determine Serum FT3, FT4 and TSH concentration. The thyroid gland was excised and processed for light microscopic examination; while the activities of G6PDH, LDH, ALP, MDA and SOD were assayed from the thyroid tissue homogenates. Results: Histological observation of thyroid gland of rats from the experimental treated groups revealed markedly distended follicles and diffusely hyperplastic thyroid follicles lined with tall columnar epithelial cells. These thyroid epithelial cells are crowded and enlarged projecting into the lumens of their respective follicles. Their interstitial tissue all had dilated blood vessels. Application of one-way ANOVA statistical analytical method showed that there were highly significant differences P˂0.05 in the activities of G6PDH, LDH, ALP, MDA, SOD, FT3, FT4 and TSH when compared with those of the control group. Conclusion: The results obtained from this study showed hyperthyroidism was effectively induced by cyanide.