Morphological changes in some endocrine organs in rats following chronic lithium treatment

Chronic prophylactic administration of lithium, a well-known anti-manic drug, has been reported to have a wide number of potential side effects involving metabolic, reproductive and endocrine systems. Since most of the existing literature reports on biochemical changes, the present investigations were undertaken to examine whether chronic lithium treatment could lead to morphological alterations in various endocrine organs. Sexually adult male Fischer rats, acclimatized to standardized laboratory conditions of light (LD 14:10) and temperature (21-23 degrees C) for 2 weeks, were treated with lithium by feeding a specially prepared chow containing 0.4% lithium chloride. The diet was administered for 15 d to one group and for 30 d to the other after which the animals were decapitated and the thyroid, adrenal, pancreas, testis and seminal vesicles were quickly dissected out and fixed in 10% neutral formalin. After routine histological procedures, 5 microns thick paraffin sections were stained by hematoxylin-eosin or Gomori's trichrome stain and examined under light microscope. Definitive morphological alterations were noted in the thyroid gland in that chronic lithium led to significant reduction in the epithelial height of the follicular cells and in an increase in colloidal content, suggesting a hypothyroid condition. Chronic lithium also resulted in decreased epithelial height in the seminal vesicle; the mucosal pseudostratified columnar epithelium regressed to an almost squamous epithelium. No discernible morphological changes were evident in the other endocrine glands studied. These results provide important morphological correlates and support some of the biochemical studies reported earlier on the potential adverse effects of lithium.