Biological effects of lithium chloride on Herpetomonas muscarum muscarum and Blastocrithidia culicis (Kinetoplastida : Trypanosomatidae)

Lithium is widely used in medicine as an antidepressive drug and for myelos uppression attenuation during chemotherapy. In spits of abundant literature , questions on the biological action of lithium ions are far from being ans wered. We have here examined the effects of lithium (10-200 mM) on culture forms of the trypanosomatid protozoa Herpetomonas,muscarum muscarum and Bla stocrithidia culicis. Incubation of these parasites with LiCl inhibited cel l growth in a concentration-dependent manner, but growth could be restored when the drug was removed from the medium. Furthermore, Li+ induced cell di fferentiation in H. m. muscarum. Light microscopy examination of cell viabi lity, using erythrosin B staining, showed that all treated parasites remain ed viable with all drug concentrations used. Ultrastructural analysis by tr ansmission electron microscopy showed that the cells presented no signs of degeneration. However, in H. m. muscarum the nuclei lost their peripheral h eterochromatin and appeared filled with a homogeneous matrix, whereas in B. culicis an increased amount of lipid droplets was present in the cytoplasm . Our data show that LiCl treatment arrested the cell division process, sti mulated cell differentiation, and affected the metabolism of these parasite s.