Histological study on withdrwal of chronic lithium therapy on rabbits thyroid

ABSTRACT

Sixty male adult albino rabbits were divided into two groups, control and experimental. Each group was divided into three sub-groups. Lithium Carbonate powder 34.2 mg per kg body weight was administered daily by oral route in the form of capsule for four weeks to the experimental group. The control group was given empty capsule and normal diet. Animal weight and serum lithium levels were measured at the beginning of the experiment and were checked weekly. After four weeks, one third of the animal in each group were sacrificed and thyroid were examined to see the affect of drugs on them. Second group was sacrificed after one week of withdrawal and third group after two weeks of withdrawal. The serum lithium levels drop significantly after two weeks of withdrawal but did not reach the base line. There was significant increase in the weight of the animals, weight and relative tissue weight index of the thyroid, mostly due to congestion as hyperplasia and hypertrophy seen after two weeks of withdrawal had no significant increase as compared to the other experimental groups. Therefore, significant increase in weight of thyroid after two weeks of withdrawal can be attributed to persisting lithium in tissues or rebound phenomenon