The effect of chronic lithium treatment on the sialic acid content in rat brain synaptosomes.

Rats were fed a lithium-containing diet for five weeks (40 mmol LiCl/kg fodder). Plasma lithium concentration was 0.44 mmol Li+/l plasma. The synaptosomes were isolated an incubated with 3H-glucosamine for 60 min. The glycopeptides and the gangliosides were extracted and the sialic acid content and the 3H-sialic acid content were measured. The lithium treatment produced an increase in the synaptosomal glycopeptide content. The sialic acid content was simultaneously increased in glycopeptides as well as gangliosides. The specific activity of sialic acid was reduced to 75% of the control value in the sialoglycopeptide fraction.