Light and Electron Microscopic Study on the Effect of Lithium Carbonate on the Thyroid Gland of Adult Male Albino Rat

Introduction: Lithium carbonate is the treatment of choice for acute manic episodes. It is often referred to as an anti- manic drug as it prevents mood swings in patients with manic- depressive disorder. Thyroid disturbances during lithium treatment had been reported. Aim of the Work: This research was performed to study the effect of lithium carbonate on the thyroid gland of albino rat and the possibility of recovery after drug withdrawal. Materials and Methods: Thirty adult male albino rats were divided into three equal groups; Group I (Control Group), group II received lithium carbonate at a daily dose of 14.4 mg for each rat for 6 weeks orally and group III received the same dose of lithium carbonate as group II and then left untreated for another 6 weeks to study the possibility of recovery after the drug withdrawal. The specimens were prepared for light and electron microscopic examination. Results: Sections of lithium carbonate treated rats showed enlarged irregular shaped thyroid follicles with papillary infoldings projecting into the follicular lumena. Detached and desquamated follicular cells were seen in the follicular colloid. The follicular cells showed apparent hyperplasia and bizarre-appearing nuclei. The interstitial tissue showed cellular infiltration, presence of deeply eosinophilic large cells and fibrosis in some specimens. Ultrastructurally, there was cellular debris in the follicular lumena. Some follicles showed dark follicular cells containing electron dense cytoplasm and indistinct organelles. The above structural changes were much less pronounced in group III (Recovery Group). Conclusion: Lithium carbonate induced histological changes in the thyroid gland of albino rat and most of these changes were seen to be improved after withdrawal of the drug. So, the use of this drug should be justified in clinical situation under direct medical supervision.