Li-treated Rats Research Articles

Monoamine uptake into synaptosomes from various regions of rat brain following lithium administration and withdrawal

The uptake of monoamines into synaptosomes from various regions of rat brain was examined following lithium (Li) treatment (2 mequiv/kg/day) and subsequent withdrawal. In control animals, regional differences were noted in the amount of NA, DA and 5-HT taken up. The consequences of Li administration were found to depend upon the monoamine examined. Dopamine uptake was enhanced, while that of 5-HT was depressed in all regions studied. The effects on NA uptake were seen to be regionally variable, being enhanced in the hypothalamus and striatum and depressed in the midbrain and cortex. Lithium withdrawal resulted in a return towards control values for all regions and substrates except striatum (DA and 5-HT) and midbrain (5-HT), where the uptake remained unaltered or was enhanced with respect to the Li-treated rats. It is suggested that part of the therapeutic effect of Li in mania is due to alterations in the uptake processes for the monoamines, and that the “rebound” mania seen clinically following Li withdrawal may be associated with dopaminergic and tryptaminergic systems, particularly in the striatum and midbrain.