Protective Effect of Zinc Sulfate on Hypo-and Hyperthyroidism Induced in Adult Male Rabbits

The present study was conducted to investigate the effect of co-administration of zinc sulfate with Carbimazole (CBZ) and, Levothyroxine (L-T 4 ) on thyroid gland function in adult male rabbits. Fifty adult male rabbits, were divided randomly into five equal groups (6 rabbits/group) as follows: The first group (control group): Rabbits were given oral doses of distilled water daily by gavage; second group (Hypothyroidism): Rabbits were given oral doses of carbimazole (5 mg/kg. bw) daily by gavage; the third group; Rabbits were given oral doses of carbimazole (5 mg/kg. bw) + zinc sulfate (20 mg/kg.bw); fourth group (Hyperthyroidism): Rabbits were given oral doses of L-T 4 (100µg/kg.bw) daily by gavage; Fifth group: Rabbits were given oral doses of L-T 4 (100µg/kg.bw) + Zinc sulfate (20mg/kg.bw) daily by gavage. The treatment continued for 30 days. The results revealed the following: A significant elevation in serum TSH level and a significant reduction in serum T 4 , T 3 and, FT 3 levels in CBZ treated rabbits group compared with the control group, while a significant reduction in serum TSH level and a significant elevation in serum levels of T 4 , FT 4 and FT 3 in animals group treated with the L-T 4 compared with the control group Histopathological changes of hypothyroidism were observed in CBZ treated group characterized by small thyroid follicles, increase the height of thyrocytes hyperplasia, and vacuolation of colloid. L-T 4 and L-T4-Zinc treated groups showed large follicles distended with homogenous acidophilic colloid. No significant changes in thyroid architecture were observed in CBZ-Zinc treated group compared with the control group.