Action Of Lithium Research Articles

The role of lithium in the treatment of bipolar disorder: convergent evidence for neurotrophic effects as a unifying hypothesis

Lithium has been and continues to be the mainstay of bipolar disorder (BD) pharmacotherapy for acute mood episodes, switch prevention, prophylactic treatment, and suicide prevention. Lithium is also the definitive proof-of-concept agent in BD, although it has recently been studied in other psychoses as well as diverse neurodegenerative disorders. Its neurotrophic effects can be viewed as a unifying model to explain several integrated aspects of the pathophysiology of mood disorders and putative therapeutics for those disorders. Enhancing neuroprotection (which directly involves neurotrophic effects) is a therapeutic strategy intended to slow or halt the progression of neuronal loss, thus producing long-term benefits by favorably influencing outcome and preventing either the onset of disease or clinical decline. The present article: (i) reviews what has been learned regarding lithium's neurotrophic effects since Cade's original studies with this compound; (ii) presents human data supporting the presence of cellular atrophy and death in BD as well as neurotrophic effects associated with lithium in human studies; (iii) describes key direct targets of lithium involved in these neurotrophic effects, including neurotrophins, glycogen synthase kinase 3 (GSK-3), and mitochondrial/endoplasmic reticulum key proteins; and (iv) discusses lithium's neurotrophic effects in models of apoptosis and excitotoxicity as well as its potential neurotrophic effects in models of neurological disorders. Taken together, the evidence reviewed here suggests that lithium's neurotrophic effects in BD are an example of an old molecule acting as a new proof-of-concept agent. Continued work to decipher lithium's molecular actions will likely lead to the development of not only improved therapeutics for BD, but to neurotrophic enhancers that could prove useful in the treatment of many other illnesses.

Lithium specificity in bipolar illness: a classic agent for the classic disorder

For over half a century, lithium has been the gold standard amongst the pharmacological armamentarium used to treat bipolar disorder. Its ascendancy in this regard has been attributed partly to its primacy of discovery and clinical implementation; however, it is important to consider how it has achieved success and retained its prominence and whether this is because of its unique profile and specificity of actions. In this paper, we briefly discuss the clinical evidence in support of lithium specificity and argue for its continuing use in those patients most likely to benefit, namely, patients with 'classic' bipolar disorder. Further, we suggest that accurate characterization of 'lithium responders' through focused research is likely to yield novel treatments and assist in better understanding of the pathophysiology of the illness. In addition, the unique antisuicidal actions of lithium warrant further examination, as do its impressive properties as a prophylactic agent. This is particularly so given the high morbidity associated with bipolar disorder and its potential for suicide. Hence, in this paper, after describing the changing diagnostic backdrop against which much of the research to date has been conducted, we discuss the clinical therapeutic profile of lithium in both the acute and long-term management of bipolar disorder and its phenotypic specificity of action. We demonstrate that lithium possesses significant clinical and therapeutic efficacy that is very individual and thus remains the treatment of choice for bipolar disorder when used specifically in select patients.

Effects of lithium chloride on the gene expression profiles in Drosophila heads

To gain insight into the basic neurobiological processes regulated by lithium—an effective drug for bipolar disorder—we used Affymetrix Genome Arrays to examine lithium-induced changes in genome-wide gene expression profiles of head mRNA from the genetic model organism Drosophila melanogaster. First, to identify the individual genes whose transcript levels are most significantly altered by lithium, we analyzed the microarray data with stringent criteria (fold change > 2; p < 0.001) and evaluated the results by RT-PCR. This analysis identified 12 genes that encode proteins with various biological functions, including an enzyme responsible for amino acid metabolism and a putative amino acid transporter. Second, to uncover the biological pathways involved in lithium's action in the nervous system, we used less stringent criteria (fold change > 1.2; FDR < 0.05) and assigned the identified 66 lithium-responsive genes to biological pathways using DAVID (Database for Annotation, Visualization and Integrated Discovery). The gene ontology categories most significantly affected by lithium were amino acid metabolic processes. Taken together, these data suggest that amino acid metabolism is important for lithium's actions in the nervous system, and lay a foundation for future functional studies of lithium-responsive neurobiological processes using the versatile molecular and genetic tools that are available in Drosophila.

Lithium Pharmacodynamics and Pharmacogenetics: Focus on Inositol Mono Phosphatase (IMPase), Inositol Poliphosphatase (IPPase) and Glycogen Sinthase Kinase 3 Beta (GSK-3 Beta)

The mechanisms of lithium action are not known in detail. First messengers, second messengers, and gene expression all appear to be involved: the wide breadth of targets makes the lithium therapeutic path difficult to disentangle. In the present paper, we focused on the most direct biochemical lithium targets at therapeutic concentration, for which some pharmacogenetic finding is present (i.e. inositol mono phosphatase (IMPase), inositol polyphosphate-1-phosphatase (IPPase) and glycogen sinthase kinase 3 beta (GSK-3 beta)). They are all inhibited by lithium at therapeutic concentrations and are representative of the inositol depletion and of the GSK-3 beta based theories of lithium action. Then we surveyed gene variants on those targets that have been associated also with bipolar disorder. On the basis of the molecular characteristics of these proteins, we suggest a set of critical genetic variations. IMPase2, IPPase and GSK-3 beta gene appear to be good candidates for the analysis of lithium prophylactic efficacy and bipolar disorder phenotypes but the genetic association analysis conducted so far reported negative or not unequivocal finding. This may be due to the incomplete coverage of gene mutations in most studies or to the several actions that lithium is thought to perform and trigger in cell machinery, including receptors, calcium equilibrium, gene expression, activation of neuroprotective paths and other yet undetected or less considered mechanisms.

Differential modulation of intracellular Ca2+ responses in B lymphoblasts by mood stabilizers

Irregularities of intracellular calcium (Ca2+) homeostasis have been implicated in the pathophysiology of bipolar disorder (BD). Findings that chronic ex-vivo treatment with lithium modifies lysophosphatidic acid (LPA)-stimulated Ca2+ responses in B lymphoblast cell lines (BLCLs) from BD-I patients and healthy controls, and differentially decreases levels of the type-3 canonical transient receptor potential Ca2+-permeable channel in BLCLs from BD-I patients, support the view that the amelioration of these abnormalities is important in the therapeutic action of lithium. To determine whether other clinically efficacious mood stabilizers share these effects, LPA (100 mum)- and thapsigargin (TG, 200 nm)-stimulated Ca2+ responses were determined in BLCLs from BD-I patients and healthy controls treated acutely (24 h) and chronically (7 d) ex vivo with therapeutically relevant concentrations of lithium (0.75 mm), valproate (0.5 mm), lamotrigine (15 mum) or respective vehicles. Chronic treatment with valproate significantly attenuated LPA-stimulated Ca2+ responses ([downward arrow]8%: F's=9.1-9.4, d.f.=1, 9, p's<0.05) compared to vehicle in BLCLs from BD-I patients and healthy controls, similar to chronic lithium treatment ([downward arrow]8%: F=6.2, d.f.=1, 21, p<0.05), but also attenuated TG-evoked Ca2+ responses ([downward arrow]10% to [downward arrow]19%: F's=5.5-15.5, d.f.=1, 12, p's<0.05). However, chronic lamotrigine treatment did not affect LPA- or TG-stimulated Ca2+ responses. These results suggest that chronic lithium and valproate treatments act differently from lamotrigine in respect of modulation of receptor- and/or capacitance-mediated Ca2+ flux. These differential effects on Ca2+ responses may be relevant to the distinctive clinical profiles of these mood stabilizers.

NMDA receptor antagonists augment antidepressant-like effects of lithium in the mouse forced swimming test

Although there is evidence of the involvement of N-methyl-D-aspartate receptors (NMDAR) in the action of lithium, its role in the antidepressant effects of lithium in a behavioural model remains unclear. In this study, we evaluated the effects of NMDAR antagonists on the antidepressant-like effects of lithium in the mouse forced swimming test. Lithium (30 and 100 mg/kg, i.p.) significantly (P < 0.01) reduced the immobility times of mice, whereas at lower doses (5 and 10 mg/kg) had no effect. NMDA antagonists ketamine (2 and 5 mg/kg, i.p.), MK-801 (0.1 and 0.25 mg/kg, i.p.) and ifenprodil (1 and 3 mg/kg, i.p.) significantly (P < 0.05) decreased the immobility time. Lower doses of ketamine (0.5 and 1 mg/kg), MK-801 (0.01 and 0.05 mg/kg) and ifenprodil (0.1 and 0.5 mg/kg) had no effect. Combined treatment of subeffective doses of lithium (10 mg/kg) and ketamine (1 mg/kg), MK-801 (0.05 mg/kg) or ifenprodil (0.5 mg/kg) robustly (P < 0.001) exerted an antidepressant-like effect. The noneffective dose of a NMDA agonist (NMDA, 75 mg/kg, i.p.) prevented the antidepressant-like effect of lithium (30 mg/kg). None of the drugs at subactive doses or in combination with lithium had significant effect on the locomotor activity in the open field test. We for the first time suggested a role for NMDAR signalling in the antidepressant-like effects of lithium, providing a new approach for treatment of depression.

Lithium action on glucose transport in insulin‐resistant rat skeletal muscle: roles of insulin signaling and p38 MAPK

In insulin‐sensitive rat skeletal muscle, lithium activates glucose transport via a mechanism involving p38 mitogen‐activated protein kinase (p38 MAPK). The mechanism underlying lithium action on glucose transport in insulin‐resistant rat skeletal muscle is unknown. We therefore assessed the effects of lithium on basal and insulin‐stimulated glucose transport, insulin signaling (insulin receptor (IR), Akt, and glycogen synthase kinase‐3 (GSK‐3)), and p38 MAPK in soleus muscle from obese Zucker rats. Lithium (10 mM LiCl) increased basal glucose transport by 49% (p&lt;0.05). Lithium did not induce basal IR tyrosine phosphorylation, but did enhance Akt ser473 phosphorylation (40%) and GSK‐3β ser9 phosphorylation (88%). Lithium potentiated insulin action on glucose transport (74%), Akt ser473 phosphorylation (39%), and GSK‐3β ser9 phosphorylation (36%), and elicited robust increases in p38 MAPK phosphorylation both in the absence (100%) or presence (88%) of insulin. Selective inhibition of p38 MAPK (using 10 µM A304000) completely blocked basal activation of glucose transport by lithium, and significantly reduced (42%) the lithium‐induced enhancement of insulin‐stimulated glucose transport. These results indicate that lithium enhances basal and insulin‐stimulated glucose transport and distal insulin signaling in insulin‐resistant skeletal muscle of obese Zucker rats via engagement of p38 MAPK.

Lithium and genetic inhibition of GSK3β enhance the effect of methamphetamine on circadian rhythms in the mouse

Lithium, a drug commonly used to treat mood disorders, and the psychostimulant methamphetamine are both capable of altering circadian rhythmicity. Although the actions of lithium on the circadian system are thought to occur through inhibition of glycogen synthase kinase-3beta (GSK3beta), the mechanism by which methamphetamine alters circadian rhythms is unknown. We tested the effects of concurrent methamphetamine and lithium treatment on the circadian wheel-running behavior of mice. Methamphetamine alone lengthened both the active duration and the free-running period of locomotor activity in animals housed in constant conditions. Administering lithium enhanced the period-lengthening effects of methamphetamine in animals housed in constant darkness. This effect was even more pronounced when animals were housed in constant light. Lithium increased both methamphetamine intake and serum levels of methamphetamine, possibly contributing to the effects on circadian behavior. We also tested the effect of methamphetamine in mutant mice possessing only one allele for Gsk3beta. These animals, when treated with methamphetamine, responded like wild-type mice treated with a combination of methamphetamine and lithium, displaying long, free-running rhythms. These data, together with many others in the literature, point to a complicated interaction between the circadian system and the development and possible treatment of psychopathologies such as bipolar disorder and drug addiction.

Lithium treatment in cluster headache: review of literature

Background: The pain, which is involved in Cluster Headache (CH), is excruciating and is probably one of the most painful conditions known to humans. In the early 70es it was found out that lithium could be used in treating this rare condition. Ekbom produced his first report of using lithium successfully to treat five cases of CH and this was followed later by other studies, which showed the effectiveness of lithium in this condition. Objective: In this article we reviewed the evidence for using lithium in CH. We discuss some issues including the duration, the dosage of lithium required and the short and longterm side effects, which are likely to occur. We also included the mechanism of action of lithium in treating this condition. Methodology: We searched the Medline database from 1950 to date. We included all studies done in English, which were related to the use of lithium in cluster headache. We excluded all studies which were not in English and which included other types of headache. Results and conclusions: We concluded that lithium is effective in both chronic and episodic forms of cluster Headache. Received 9 January 2008 Revised 2 December 2008 Accepted 11 December 2008 54 M.B. ABDEL-MAKSOUD ET AL.

Down‐regulation of NR4A1 in follicular thyroid carcinomas is restored following lithium treatment

The identification of follicular thyroid adenoma-associated transcripts will lead to a better understanding of the events involved in pathogenesis and progression of follicular tumours. Using Serial Analysis of Gene Expression, we identified five genes that are absent in a malignant follicular thyroid carcinoma (FTC) library, but expressed in follicular adenoma (FTA) and normal thyroid libraries. NR4A1, one of the five genes, was validated in a set of 27 normal thyroid tissues, 10 FTAs and 14 FTCs and three thyroid carcinoma cell lines by real time PCR. NR4A1 can be transiently increased by a variety of stimuli, including lithium, which is used as adjuvant therapy of thyroid carcinoma with (131)I. We tested if lithium could restore NR4A1 expression. The expression of other genes potentially involved in the same signalling pathway was tested. To this end, lithium was used at different concentration (10 mm or 20 mm) and time (2 h and 24 h) and the level of expression was tested by quantitative PCR. We next tested if Lithium could affect cell growth and apoptosis. We observed that NR4A1 expression was under-expressed in most of the FTCs investigated, compared with expression in normal thyroid tissues and FTAs. We also found a positive correlation between NR4A1 and FOSB gene expression. Lithium induced NR4A1 and FOSB expression, reduced CCDN1 expression, inhibited cell growth and triggered apoptosis in a FTC cell line. NR4A1 is under-expressed in most of FTCs. The loss of expression of both NR4A1 and the Wnt pathway gene FOSB was correlated with malignancy. This is consistent with the hypothesis that its loss of expression is part of the transformation process of FTCs, either as a direct or indirect consequence of Wnt pathway alterations. Lithium restores NR4A1 expression, induces apoptosis and reduces cell growth. These findings may explain a possible molecular mechanism of lithium's therapeutic action.

Lithium's Antisuicidal Efficacy: Elucidation of Neurobiological Targets Using Endophenotype Strategies

Lithium used as a drug treatment for major mental disorders such as bipolar disorder and depression is effective in reducing the risk of both attempted and completed suicide. However, the mechanisms underlying lithium's antisuicidal actions are not yet known, limiting the development of novel lithium-mimetic compounds that may help reduce suicide risk with fewer undesirable side effects. Suicide is a complex behavior, complicated to study in humans, and impossible to fully reproduce in animal models. The endophenotype approach, by which quantitative measures of neurobiological function are used to assess and subclassify psychiatric illness, may present a path to new discoveries. Aggression and impulsivity are candidate endophenotypes strongly associated with suicide; we review the evidence supporting aggression and impulsivity as suicide endophenotypes, as well as the effects of lithium on these constructs in both humans and rodents. Examining the mechanisms that contribute to lithium's antiaggressive and antiimpulsive effects may assist in understanding how lithium acts to reduce the risk of suicide and in elucidating the neurobiological underpinnings of suicidal behavior.

Lithium chloride protects retinal neurocytes from nutrient deprivation by promoting DNA non-homologous end-joining

Lithium chloride is a therapeutic agent for treatment of bipolar affective disorders. Increasing numbers of studies have indicated that lithium has neuroprotective effects. However, the molecular mechanisms underlying the actions of lithium have not been fully elucidated. This study aimed to investigate whether lithium chloride produces neuroprotective function by improving DNA repair pathway in retinal neurocyte. In vitro, the primary cultured retinal neurocytes (85.7% are MAP-2 positive cells) were treated with lithium chloride, then cultured with serum-free media to simulate the nutrient deprived state resulting from ischemic insult. The neurite outgrowth of the cultured cells increased significantly in a dose-dependent manner when exposed to different levels of lithium chloride. Genomic DNA electrophoresis demonstrated greater DNA integrity of retinal neurocytes when treated with lithium chloride as compared to the control. Moreover, mRNA and protein levels of Ligase IV (involved in DNA non-homologous end-joining (NHEJ) pathway) in retinal neurocytes increased with lithium chloride. The end joining activity assay was performed to determine the role of lithium on NHEJ in the presence of extract from retinal neurocytes. The rejoining levels in retinal neurocytes treated with lithium were significantly increased as compared to the control. Furthermore, XRCC4, the Ligase IV partner, and the transcriptional factor, CREB and CTCF, were up-regulated in retinal cells after treating with 1.0 mM lithium chloride. Therefore, our data suggest that lithium chloride protects the retinal neural cells from nutrient deprivation in vitro, which may be similar to the mechanism of cell death in glaucoma. The improvement in DNA repair pathway involving in Ligase IV might have an important role in lithium neuroprotection. This study provides new insights into the neural protective mechanisms of lithium chloride.

Stimulation by lithium of the interaction between the transcription factor CREB and its co-activator TORC

Lithium salts are clinically important drugs used to treat bipolar mood disorder. The mechanisms accounting for the clinical efficacy are not completely understood. Chronic treatment with lithium is required to establish mood stabilization, suggesting the involvement of neuronal plasticity processes. CREB (cAMP-response-element-binding protein) is a transcription factor known to mediate neuronal adaptation. Recently, the CREB-co-activator TORC (transducer of regulated CREB) has been identified as a novel target of lithium and shown to confer an enhancement of cAMP-induced CREB-directed gene transcription by lithium. TORC is sequestered in the cytoplasm and its nuclear translocation controls CREB activity. In the present study, the effect of lithium on TORC function was investigated. Lithium affected neither the nuclear translocation of TORC nor TORC1 transcriptional activity, but increased the promoter occupancy by TORC1 as revealed by chromatin immunoprecipitation assay. In a mammalian two-hybrid assay, as well as in a cell-free GST (glutathione transferase) pull-down assay, lithium enhanced the CREB-TORC1 interaction. Magnesium ions strongly inhibited the interaction between GST-CREB and TORC1 and this effect was reversed by lithium. Thus our results suggest that, once TORC has entered the nucleus, lithium as a cation stimulates directly the binding of TORC to CREB, leading to an increase in cAMP-induced CREB target-gene transcription. This novel mechanism of lithium action is likely to contribute to the clinical mood-stabilizing effect of lithium salts.

Proteomic Analysis of Lithium-Induced Gene Expression in the Rat Hypothalamus

The hypothalamic proteomes were analyzed 1 and 6 hr after an intraperitoneal injection of lithium chloride or sodium chloride (0.15 M, 12 ml/kg). Results showed that expression of 14 and 32 proteomes was increased consistently by 1 hr and 6 hr of lithium treatment, respectively. Among them, tentative implications of glial fibrillary acidic protein, receptor-type protein tyrosine phosphatase, spectrin, and glutamate dehydrogenase in the lithium-induced activation of the hypothalamic-pituitary-adrenal axis, and conditioned taste aversion have been discussed. The proteomes listed in this study will provide, at least, a new insight to understand the molecular mechanism of lithium's action in the brain.

Lithium and Psoriasis

This review focuses on the association of lithium treatment and psoriasis. The mechanism of action of lithium in causing psoriasis and the clinical presentation of psoriasis secondary to lithium treatment are considered. A search of the literature from 1949 to 2007 was performed using MEDLINE, with the following search terms: lithium, psoriasis, skin, dermatology, and psychodermatology. Lithium is involved in a variety of cutaneous reactions including psoriasis, which may present as exacerbation of preexisting psoriasis, induction of de novo psoriasis, pustular psoriasis, nail changes, and psoriatic arthropathy. The appearance of psoriatic lesions may occur at normal therapeutic serum lithium levels. The refractory period for the development of psoriatic lesions is variable and generally longer in induction and shorter in exacerbation of psoriasis. Lithium-induced psoriasis is often resistant to conventional treatment modalities, and some cases may require dose reduction or discontinuation of lithium treatment. Lithium is the mainstay of treatment in bipolar disorder and is associated with a variety of cutaneous side effects including psoriasis. Primary care providers and family physicians should be knowledgeable about the association of lithium and its dermatologic side effects. Early recognition and management could be beneficial in avoiding the issues of noncompliance and further deterioration of mood symptoms secondary to obviously disfiguring skin appearance. Primary care, psychiatry, and dermatology liaison services will prove helpful in managing these patients.

Lithium and cognitive enhancement: leave it or take it?

Lithium is established as an effective treatment of acute mania, bipolar and unipolar depression and as prophylaxis against bipolar disorder. Accumulating evidence is also delineating a neuroprotective and neurotrophic role for lithium. However, its primary effects on cognitive functioning remain ambiguous. The aim of this paper is to review and combine the relevant translational studies, focusing on the putative cognitive enhancement properties of lithium, specifically on learning, memory, and attention. These properties are also discussed in reference to research demonstrating a protective action of lithium against cognitive deficits induced by various challenges to the nervous system, such as stress, trauma, neurodegenerative disorders, and psychiatric disorders. It is suggested on the basis of the evidence that the cognitive effects of lithium are best expressed and should, therefore, be sought under conditions of functional or biological challenge to the nervous system.

A mutation in the calreticulin gene promoter in a family case of schizoaffective disorder leads to its aberrant transcriptional activation

We previously reported a G > C point mutation located at position − 48 within the calreticulin gene core promoter in one individual suffering from paranoid schizophrenia that has also been diagnosed with affective disorder. However, a putative bona fide functional link between this mutation in the calreticulin gene and schizoaffective disorder has remained speculative. We have carried out calreticulin genotyping and psychiatric examination of all available members of the family of the proband and found that three more members carry the − 48G > C mutation. Remarkably, two of them develop the disease with an onset and progression that are virtually identical. The third person, too young to have developed fully the disease, nevertheless displays the same symptoms as her affected relatives had at the same early age. Furthermore, transcriptional analysis of the calreticulin promoter in rat cortical neurons shows aberrant increase in transcription in the presence of the − 48G > C mutation, both at basal levels and in the presence of valproate and lithium. Our results point to a previously unknown causal role for dysregulation of calreticulin homeostasis in schizoaffective disorder by both genetic and functional analyses, and shed new light on the possible mechanisms of action of valproate and lithium in the treatment of the disease.

An Efficient Synthesis of (+/-)-Xanthorrhizol: One Pot Decyanation and Demethylation

A new and short total synthesis affording (±)-Xanthorrhizol in 90% overall yield is described. The method comprises three steps: 1) C-alkylation of 3-methoxy-4-methyl-benzylcyanide with 5-iodine-2-methyl-pent-2-ene; 2) Cmethylation of the resulting cyanide; and 3) one-pot decyanation and demethylation carried out by the action of lithium. Keywords: Xanthorrhizol, total synthesis, α-cyanocarbanion, C-alkylation, decyanation, demethylation, ether cleavage

Association analysis of nuclear receptor Rev-erb alpha gene ( NR1D1) with mood disorders in the Japanese population

Several investigations have suggested that alterations in circadian rhythms may lay the foundation for the development of mood disorder (bipolar disorder and major depressive disorder). Recently, the nuclear receptor Rev-erb alpha was reported to be related to circadian rhythms, and was shown to be involved in the biological action of lithium in vitro. These evidences indicate that the nuclear receptor Rev-erb alpha gene ( NR1D1) is a good candidate gene for the pathogenesis of mood disorders. To evaluate the association between NR1D1 and mood disorders, we conducted a case–control study of Japanese samples (147 bipolar patients, 322 major depressive disorder patients and 360 controls) with three tagging SNPs selected by HapMap database. One SNP showed an association with bipolar disorder in females. After Bonferroni correction for multiple testing, however, this significance disappeared. No significant association was found with major depressive disorder. In conclusion, our findings suggest that NR1D1 does not play a major role in the pathophysiology of mood disorders in the Japanese population.

Preconditioning with acute and chronic lithium administration reduces ischemia/reperfusion injury mediated by cyclooxygenase not nitric oxide synthase pathway in isolated rat heart

Lithium is widely used for the management of neuropsychiatric symptoms in bipolar disorders. A variety of hypotheses have been invoked to explain the mechanism of action of lithium. To determine if lithium exerts direct cardiac protection, in the present study perfused rat heart model was used. The mechanism of lithium-mediated cardioprotection was explored by combined use of lithium and nitro- l-arginine methyl ester (L-NAME, a non-selective nitric oxide synthase inhibitor) or indomethacin (a non-selective cyclooxygenase pathway inhibitor). Rat isolated hearts were used for Langendorff perfusion. Hearts were either non-preconditioned or preconditioned with acute lithium (3 mM) or chronic lithium (600 mg/l in tap water for 4 weeks, 0.265 ± 0.023 mM in serum) before 30 min global ischemia followed by 90 min reperfusion. Within each of these protocols, hearts were divided into two groups; one group was exposed to L-NAME (0.1 mM) and another group was exposed to indomethacin (10 µM). Infarct size was measured by the triphenyltetrazolium chloride method. Left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate and coronary flow (CF). In our experiment acute and/or chronic administration of lithium before prolonged ischemia offered significant myoprotective effects in terms of infarct size reduction and improved cardiac function against ischemia/reperfusion injury. The effects of lithium pretreatment were prevented by the administration of indomethacin but not L-NAME. In conclusion, our results demonstrate that preconditioning with acute and/or chronic lithium administration improves recovery of the ventricular function and reduces infarct size via cyclooxygenase (COX) pathway in isolated rat heart.