Lithium treatment causes gliosis and modifies the morphology of hippocampal astrocytes in rats

THE biological basis of the clinical efficacy of lithium in the treatment o f mental illness has been extensively studied in neurones, but little is kn own about the effects of the drug on glia. Recently we showed that treatmen t of rats with clinically relevant doses of lithium chloride results in a 3 5% increase in the immunocontent of the astrocyte marker GFAP in the hippoc ampus. Here we studied the cytology of this phenomenon. Rats were treated f or 4 weeks with a lithium diet which resulted in serum Li+ concentrations o f 0.6-1.2 mmol/l. GFAP immunocytochemistry of the hippocampus revealed a mi ld gliosis in the CA1 area and the dentate gyrus which was associated with a change in the orientation of astrocytic processes. In control animals ast rocyte processes mere mainly orientated perpendicular to the stratum pyrami dale, whereas in treated animals the cells were predominantly stellar in ap pearance. NeuroReport 9: 3971-3974 (C) 1998 Lippincott Williams & Wilkins.