COMPARISON OF THE CHANGES IN CENTRAL CATECHOLAMINE SYSTEMS FOLLOWING SHORT-TERM AND LONG-TERM LITHIUM TREATMENT AND THE CONSEQUENCES OF LITHIUM WITHDRAWAL

The effects of treatment with and withdrawal from Li (2 mmol/kg) on central catecholamine systems in rat brain were investigated. Synthetic parameters were unchanged after treatment, but abrupt withdrawal resulted in enhanced activity of tyrosine hydroxylase. Noradrenaline [norepinephrine] levels in most brain regions examined were depressed following both short- and long-term Li administration, with a further decrease in content in the pons but enhanced cortical levels on withdrawal. Li administration resulted in elevated 3,4-dihydroxyphenylacetic acid levels, whereas withdrawal caused an enhancement of homovanillic acid content and depression of 3-methoxy-4-hydroxyphenyl glycol levels. The changes in central catecholamine systems are apparently qualitatively the same following both short- and long-term Li treatment, as are the consequences of abrupt Li withdrawal. Evidently, Li administration results in a disruption of catecholamine storage processes, while withdrawal from Li does not result in a simple return towards normal states.