Lithium therapy for mania and depression

Modifications of excitatory and inhibitory transmission in rat hippocampal pyramidal neurons by acute lithium treatment

The acute effects of high-dose Li(+) treatment on glutamatergic and GABAergic transmissions were studied in the "synaptic bouton" preparation of isolated rat hippocampal pyramidal neurons by using focal electrical stimulation. Both action potential-dependent glutamatergic excitatory and GABAergic inhibitory postsynaptic currents (eEPSC and eIPSC, respectively) were dose-dependently inhibited in the external media containing 30-150 mM Li(+), but the sensitivity for Li(+) was greater tendency for eEPSCs than for eIPSCs. When the effects of Li(+) on glutamate or GABAA receptor-mediated whole-cell responses (IGlu and IGABA) elicited by an exogenous application of glutamate or GABA were examined in the postsynaptic soma membrane of CA3 neurons, Li(+) slightly inhibited both IGlu and IGABA at the 150 mM Li(+) concentration. Present results suggest that acute treatment with high concentrations of Li(+) acts preferentially on presynaptic terminals, and that the Li(+)-induced inhibition may be greater for excitatory than for inhibitory transmission.

Lithium maintenance therapy for bipolar I patients: possible refractoriness to reinstitution after discontinuation

Recent reports of negative responsiveness in some bipolar I patients to attempts to reinstitute lithium treatment once discontinued are reviewed.

Lithium treatment and prophylaxis in unipolar depression: a meta-analysis

Meta-analysis was used to establish the efficacy of lithium in acute treatment and prophylaxis of depressive illness from existing published clinical trials. Effect sizes were measured by the odds ratio using the Mantel-Haenszel method and the Pearson product-moment correlation coefficient. Some benefit from lithium, compared with other treatments, emerged from trials of acute treatment. Lithium was clearly superior to placebo in the acute treatment of bipolar depressed patients. In controlled studies of lithium prophylaxis over five months to three years, an impressive effect was found for lithium when compared with placebo. For uncontrolled studies there was a similar-sized effect, corresponding to an improvement in the rate of favourable outcome from 35% for placebo to 70% with lithium treatment. The comparison of lithium with other antidepressants in prophylaxis showed no conclusive advantage for lithium in unipolar illness. There is no reason to doubt the efficacy of lithium in the prophylaxis of unipolar depressive illness.

Acute effects of lithium on synaptic transmission in rat hippocampus studied in vitro

Acute effects of lithium on synaptic transmissions in the CA1 neurones of rat hippocampus were examined. Perfusion of 2-10 mM lithium chloride (LiCl) produced a dose-dependent increase in the amplitude of field EPSPs, whereas change in the population spikes was variable. The increasing ratio of second field EPSP, which was examined by paired-pulse stimulation, was reduced about 10% by 5 mM LiCl. Intracellularly recorded EPSPs and IPSPs were facilitated by 10 mM LiCl, and the soma membrane was depolarized about 3.2 mV. Intracellular calcium concentration was measured in single hippocampal neurones using fura-2. Although calcium concentration at rest was approximately 30 nM and was increased to an average of 220 nM by 10(-5) M glutamate, 10 mM LiCl had no influence on it. The effects of Li on calcium-dependent processes were not manifested in this study. Variable changes of population spikes may be dependent on the balance between the excitatory and inhibitory postsynaptic potentials during lithium application.

New applications of lithium therapy

Several placebo-controlled double-blind studies have indicated that lithium sometimes augments antidepressants, converting nonresponding patients to responders. Lithium therapy has also benefitted some schizoaffective patients and some alcoholics. Side effects are minimal. Mechanisms involved in lithium's effectiveness have not yet been discovered.

Lithium increases dynorphin A(1-8) and prodynorphin mRNA levels in the basal ganglia of rats

The aim of this study was to understand the possible influence of the antimanic drug, lithium, and the neuroleptic, haloperidol, alone or in combination, on the regulation of dynorphin biosynthesis in the striatum. The study was done using male Fisher-344 rats subjected to a regimen of subchronic administration of lithium chloride (4 mEq/kg/day for 1,2,4 or 6 days, i.p.) or a regimen of chronic oral administration of a diet containing lithium carbonate (1.5 g/kg of the diet). Subchronic administration of lithium increased striatal dynorphin A(1-8)-like immunoreactivity (DN-LI) in a time-related fashion. Immunocytochemistry revealed an increase in DN-LI in fibers and cells clustered in 'patches' throughout striatum. The increase in DN-LI was reversible on cessation of lithium administration. Concurrent administration of lithium and an opiate antagonist, naltrexone, or a dopamine receptor antagonist, haloperidol, did not influence the changes induced by lithium. Chronic oral administration of lithium for 21 days led to an increase in DN-LI in the striatum. Co-administration of haloperidol with the 21 day regimen of lithium administration failed to affect the increase in DN-LI. The prodynorphin mRNA abundance in the striatum was quantitated by a molecular hybridization procedure using a prodynorphin 32P-cRNA probe generated from the Riboprobe system. Evidence from the Northern blot analysis reveals that lithium increases the prodynorphin mRNA abundance in the striatum. These results indicate that lithium affects the dynamics of prodynorphin biosynthesis in the striatum, presumably increasing transcription and/or translational processes.

Prevalence, pathogenesis, and treatment of renal dysfunction associated with chronic lithium therapy

From the analysis of several studies published from 1979 to 1986 comprising 1,172 patients, we estimated that glomerular filtration rate (GFR) was normal in 85% of unselected patients on chronic lithium therapy. The remaining 15% of patients displayed only mild reduction in GFR, clustering at approximately 60 mL/min. Thus, the data available to date do not support earlier concerns that long-term lithium therapy could eventuate into renal insufficiency. The most prevalent renal effect of lithium is impairment of concentrating ability, which we estimated to be present in at least 54% of 1,105 unselected patients on chronic lithium therapy. This defect translated into overt polyuria in only 19% of unselected cases. A renal lesion confined to the collecting tubule has been described in humans who have taken lithium for short periods of time. This lesion may represent the collecting tubule's response to the intracellular accumulation of lithium, which interferes with cAMP formation and results in an early and probably reversible inhibition of antidiuretic hormone (ADH)-mediated water transport. However, long-term lithium therapy may induce a progressive and partly irreversible defect in concentrating ability. The potential risk for dehydration associated with lithium-induced polyuria, as well as the discomfort inherent to this side effect, deserves evaluation and consideration for therapeutic intervention. Amiloride has additional advantages over conventional treatment of nephrogenic diabetes insipidus using thiazide diuretics. The action of amiloride on ADH-mediated water transport seems specific in as much as it is capable of preventing the uptake of lithium in high resistance epithelia and thereby prevents the inhibitory effect of intracellular lithium on water transport. Unlike thiazides, amiloride has a weak natriuretic effect and is less likely to increase plasma lithium levels by causing volume contraction. In addition, amiloride, by conserving potassium, obviates the need for potassium supplementation that is usually required to prevent hypokalemia when thiazides are used to treat lithium-induced polyuria. Since amiloride may prevent chronic intracellular lithium accumulation in the collecting tubule, future studies should elucidate whether amiloride also has a role in preventing lithium-induced chronic tubulo-interstitial damage.

Cancer risk from inorganics

Inorganic metals and minerals for which there is evidence of carcinogenicity are identified. The risk of cancer from contact with them in the work place, the general environment, and under conditions of clinical (medical) exposure is discussed. The evidence indicates that minerals and metals most often influence cancer development through their action as cocarcinogens. The relationship between the physical form of mineral fibers, smoking and carcinogenic risk is emphasized. Metals are categorized as established (As, Be, Cr, Ni), suspected (Cd, Pb) and possible carcinogens (Table 6), based on the existing in vitro, animal experimental and human epidemiological data. Cancer risk and possible modes of action of elements in each class are discussed. Views on mechanisms that may be responsible for the carcinogenicity of metals are updated and analysed. Some specific examples of cancer risks associated with the clinical use of potentially carcinogenic metals and from radioactive pharmaceuticals used in therapy and diagnosis are presented. Questions are raised as to the effectiveness of conventional dosimetry in accurately measuring risk from radiopharmaceuticals.