Distribution of lithium in different CNS areas and other tissues of adult male and female vizcacha (Lagostomus maximus maximus)

In a previous study (1) we demonstrated that lithium administration (1.0 mm ol/kg b.wt.,per day for 4 weeks) in intact vizcacha (Lagostomus maximus max imus) leads to significant histological alterations in the kidneys, ovarie and testicles, while these three tissues were not damaged in rats. Male viz cachas died within 4 days when administered LiCl 3 mmol/ kg b.wt., while fe males were not affected. The lithium renal clearance presented no changes i n either males or females. The 1.0 mmol/kg b.wt. dose was used in the exper iments (2). In this study we examined the distribution of lithium in variou s tissues of male and female vizcacha (Lagostomus maximus maximus) administ ered LiCl by injection (1 mmol/kg b.wt.) for one day (Group I) and thirty d ays (Group II). Blood sample was obtained after 24 hours (Group I) and 30 d ays (Group II). The tissues investigated were: pituitary, hypothalamus, cer ebral cortex, cerebellum, corpus callous, small and large intestine, kidney and suprarenal. The concentration of lithium in tissues and serum was dete rmined by atomic absortion spectrometry (3,4). In Group I a significant lit hium concentration increment mu mol/g of tissue was observed in all the tis sues of male vizcachas as compared to female vizcacha. A similar distributi on was obtained in animals treated for 30 days. In the pituitary, however t his difference between males and females was not significant. The male lith ium serum levels were significantly higher than those of female animals. In conclusion, we suggest that the particular structure of the cell membrane (e.g., number and characteristic of sodium channels) of each tissue and/or the intracellular mechanisms of transport, elimination and metabolism might explain the unequal lithium distribution and the difference recovery from the damage produced. The results suggest that the vizcacha could be a usefu l model for the study of lithium toxicity.