Thymus gland involution induced by lithium chloride.

Chronic treatment with lithium chloride produced significant involution of the thymus gland with histological evidence of reduced cellularity due to loss of thymic lymphocytes and a significant reduction in the weight of the gland in normal and adrenalectomized mice. Lithium also increased corticosterone levels in normal mice without changes in adrenal weights. The involution of the thymus gland is most likely due to an effect of lithium on the gland, and it is not mediated by adrenocortical mechanisms or stress.