The mood stabilizer lithium is used successfully in the treatment of bipolar affective disorder. However, treatment compliance is frequently poor and sudden withdrawal from lithium therapy is associated with a significantly increased risk of rebound mania. In this study we have used rodents to identify neurobiological changes in dopamine function occurring during chronic lithium treatment and withdrawal from chronic lithium treatment. Rats were maintained for 28 d on a lithium diet or a control diet. A subgroup had their lithium diet substituted with a control diet from day 25 of the treatment period. In-vivo microdialysis was used to study both basal dopamine release and potassium-evoked dopamine released in the shell of the nucleus accumbens. In-situ hybridization histochemistry was used to study the abundance of mRNA coding for dopamine's synthetic enzyme, tyrosine hydroxylase in the ventral tegmental area. Basal dopamine levels did not differ across any of the three treatment groups. However, the potassium-evoked dopamine release was significantly attenuated in lithium and lithium-withdrawn rats compared to control rats. Tyrosine hydroxylase mRNA abundance in the ventral tegmental area did not differ between any of the three treatment groups. These data suggest that decreased dopamine release may mediate the mood stabilizing action of lithium. However, in this paradigm a rebound increase in dopamine release was not found after withdrawal from lithium treatment.

Bipolar affective disorders can be successfully treated with long-term use of the mood stabilizer lithium. However, discontinuation of lithium treatment is followed by a high incidence of manic episodes. In the present study, we attempted to identify neurobiological changes that might mediate this rebound mania. In vivo microdialysis in the anaesthetized rat and in situ hybridization histochemistry were used to study the effect of chronic lithium treatment and withdrawal from chronic lithium treatment on presynaptic dopamine (DA) function. Rats were maintained for 28 days on a lithium diet or control diet. The lithium-withdrawn treatment group had their lithium diet substituted for control diet from day 25 of the treatment period. Microdialysis probes were implanted in the shell of the nucleus accumbens and both basal extracellular DA levels and DA levels in the presence of the DA uptake inhibitor bupropion (1 microM) were collected. Basal DA levels did not differ between any of the treatment groups. However, during local perfusion of bupropion, the increase in DA was significantly attenuated in the lithium-treated animals compared to controls or lithium-withdrawn animals. In situ hybridization of DA transporter mRNA in the ventral tegmental area revealed no difference in the abundance of this mRNA in any of the groups. These data suggest that there is impaired DA release in rats during chronic lithium treatment, but DA release returns to normal levels on withdrawal from lithium treatment, and is therefore unlikely to underlie the rebound mania associated with lithium withdrawal.

No abstract

New data have emerged over the past 10 years regarding the efficacy and mechanisms of action of lithium. This article briefly summarises the evidence for the use of lithium to treat affective disorders and psychosis, reviews its putative anti-suicidal effect, highlights new research on its mechanism of action and provides an update on some important side-effects and consequences of its use.

No abstract