THE PROBABLE PROTECTIVE ROLE OF CHITOSAN AGAINST LITHIUM-INDUCED THYROID DYSFUNCTION, EXPERIMENTAL STUDY

Background: Lithium remains a cornerstone in the long-term management of bipolar affective disorders. However, its use has been associated with multisystem toxicity including thyroid gland. Aim of the work: the study aimed to evaluate the thyrotoxic effects of sub-acute lithium carbonate in albino male adult rats, and the role of concomitant chitosan use in diminishing these effects. Methods: Sixty rats were randomly allocated into six groups. Group 1 served as the negative control. Group 2 received chitosan at a dose of 200 mg/kg/day. Group 3 was administered lithium carbonate at 25 mg/kg/day, while Group 4 received a combination of chitosan (200 mg/kg/day) and lithium carbonate (25 mg/kg/day). Group 5 was treated with lithium carbonate at 50 mg/kg/day orally, and Group 6 received both chitosan (200 mg/kg/day) and lithium carbonate (50 mg/kg/day). Animals were treated via oral gavage for four weeks; blood samples were collected for hormonal assays and oxidative stress biomarker, and after euthanasia, thyroid tissue was harvested for microscopic examination and morphometric evaluation. Results: Groups 3 and 5 showed a reduction in total T3 and total T4 , and a rise in TSH and MDA (Malondialdehyde) levels, while the addition of chitosan in groups 4 and 6 restored these levels to normal compared to control groups 1 and 2. H&E-stained sections from groups 3 and 5 revealed congestion, degeneration, and desquamation of the follicular epithelium in thyroid tissue, while morphometric analysis demonstrated a decrease in the mean luminal area with no significant change in the follicles number. The addition of chitosan in groups 4 and 6 ameliorated the histopathological effects of lithium carbonate on thyroid tissue, rendering the results comparable to the control groups. Conclusion: The hypothyroid effect of lithium carbonate is evident with prolonged administration; however, these effects can be attenuated by co-administration of chitosan as an antioxidant.