Treatment of the "on-off" phenomenon in Parkinsonism with lithium carbonate

Targeting kinases in Parkinson's disease: A mechanism shared by LRRK2, neurotrophins, exenatide, urate, nilotinib and lithium

Several kinases have been implicated in the pathogenesis of Parkinson's disease (PD), most notably leucine-rich repeat kinase 2 (LRRK2), as LRRK2 mutations are the most common genetic cause of a late-onset parkinsonism that is clinically indistinguishable from sporadic PD. More recently, several other kinases have emerged as promising disease-modifying targets in PD based on both preclinical studies and clinical reports on exenatide, the urate precursor inosine, nilotinib and lithium use in PD patients. These kinases include protein kinase B (Akt), glycogen synthase kinases-3β and -3α (GSK-3β and GSK-3α), c-Abelson kinase (c-Abl) and cyclin-dependent kinase 5 (cdk5). Activities of each of these kinases are involved either directly or indirectly in phosphorylating tau or increasing α-synuclein levels, intracellular proteins whose toxic oligomeric forms are strongly implicated in the pathogenesis of PD. GSK-3β, GSK-3α and cdk5 are the principle kinases involved in phosphorylating tau at sites critical for the formation of tau oligomers. Exenatide analogues, urate, nilotinib and lithium have been shown to affect one or more of the above kinases, actions that can decrease the formation and increase the clearance of intraneuronal phosphorylated tau and α-synuclein. Here we review the current preclinical and clinical evidence supporting kinase-targeting agents as potential disease-modifying therapies for PD patients enriched with these therapeutic targets and incorporate LRRK2 physiology into this novel model.

The combination of lithium and l-Dopa/Carbidopa reduces MPTP-induced abnormal involuntary movements (AIMs) via calpain-1 inhibition in a mouse model: Relevance for Parkinson׳s disease therapy

Lithium has recently been suggested to have neuroprotective effects in several models of neurodegenerative disease including Parkinson׳s disease (PD). Levodopa (l-Dopa) replacement therapy remains the most common and effective treatment for PD, although it induces the complication of l-Dopa induced dyskinesia after years of use. Here we examined the potential use of lithium in combination with l-Dopa/Carbidopa for both reducing MPTP-induced abnormal involuntary movements (AIMs) as well as protecting against cell death in MPTP-lesioned mice. Chronic lithium administration (0.127% LiCl in the feed) in the presence of daily l-Dopa/Carbidopa injection for a period of 2 months was sufficient to effectively reduce MPTP-induced AIMs in mice. Mechanistically, lithium was found to suppress MPTP-induced calpain activities in vivo coinciding with down-regulation of calpain-1 but not calpain-2 expression in both the striatum (ST) and the brain stem (BS). Calpain inhibition has previously been associated with increased levels of the rate-limiting enzyme in dopamine synthesis, tyrosine hydroxylase (TH), which is probably mediated by the up-regulation of the transcription factors MEF-2A and 2D. Lithium was found to induce up-regulation of TH expression in the ST and the BS, as well as in N27 rat dopaminergic cells. Further, histone acetyltransferase (HAT) expression was substantially up-regulated by lithium treatment in vitro. These results suggest the potential use of lithium in combination with l-Dopa/Carbidopa not only as a neuroprotectant, but also for reducing AIMs and possibly alleviating potential side-effects associated with the current treatment for PD.

Molecular actions and therapeutic potential of lithium in preclinical and clinical studies of CNS disorders

Lithium has been used clinically to treat bipolar disorder for over half a century, and remains a fundamental pharmacological therapy for patients with this illness. Although lithium's therapeutic mechanisms are not fully understood, substantial in vitro and in vivo evidence suggests that it has neuroprotective/neurotrophic properties against various insults, and considerable clinical potential for the treatment of several neurodegenerative conditions. Evidence from pharmacological and gene manipulation studies support the notion that glycogen synthase kinase-3 inhibition and induction of brain-derived neurotrophic factor-mediated signaling are lithium's main mechanisms of action, leading to enhanced cell survival pathways and alteration of a wide variety of downstream effectors. By inhibiting N-methyl-D-aspartate receptor-mediated calcium influx, lithium also contributes to calcium homeostasis and suppresses calcium-dependent activation of pro-apoptotic signaling pathways. In addition, lithium decreases inositol 1,4,5-trisphosphate by inhibiting phosphoinositol phosphatases, a process recently identified as a novel mechanism for inducing autophagy. Through these mechanisms, therapeutic doses of lithium have been demonstrated to defend neuronal cells against diverse forms of death insults and to improve behavioral as well as cognitive deficits in various animal models of neurodegenerative diseases, including stroke, amyotrophic lateral sclerosis, fragile X syndrome, as well as Huntington's, Alzheimer's, and Parkinson's diseases, among others. Several clinical trials are also underway to assess the therapeutic effects of lithium for treating these disorders. This article reviews the most recent findings regarding the potential targets involved in lithium's neuroprotective effects, and the implication of these findings for the treatment of a variety of diseases.

Lithium-induced neurotoxicity at serum lithium levels within the therapeutic range

OBJECTIVE

To report the occurrence of lithium-induced neurotoxicity and extrapyramidal symptoms at serum lithium levels within the therapeutic range.

CLINICAL PICTURE

On two occasions, a 73-year-old patient presented with symptoms of lithium-induced neurotoxicity and extrapyramidal symptoms when her serum lithium levels were within the therapeutic range.

TREATMENT AND OUTCOME

Both lithium-induced neurotoxicity and extrapyramidal symptoms resolved when lithium was withdrawn.

CONCLUSION

Even when serum lithium levels are within the therapeutic range, lithium-induced neurotoxicity may occur. Patients on neuroleptics and the elderly in particular may be more vulnerable to these side effects.

Disabling parkinsonism due to lithium: a case report

Two cases of disabling parkinsonism have been previously reported in association with lithium treatment and only one occurred without other signs of lithium toxicity. We report a case of an elderly female who suddenly developed disabling parkinsonism, apparently as a side effect from treatment with lithium carbonate without other signs of lithium toxicity. All neurologic symptoms completely resolved on discontinuation of lithium. Resuming lithium at serum levels below 0.7 mmol/L resulted in no further neurologic side effects, but serum levels of 0.7 to 0.9 mmol/L resulted in the return of mild Parkinson's symptoms. Older age, longer duration of lithium treatment, and high therapeutic levels of lithium may be risk factors for this side effect. Implications for clinicians are discussed.

The effects of kainic acid and 6-hydroxydopamine lesions, metal ions and GTP on in vitro binding of the D-2 dopamine agonist, [3H]N-0437, to striatal membranes

The kinetic and pharmacological profiles of the potent and selective D-2 dopamine agonist 2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin ([3H]N-0437) have recently been described. This report concerns the effects of chemical lesions and metal ions on the radioreceptor binding of [3H]N-0437. Kainic acid lesions reduced the maximum number of binding sites (Bmax) in the rat striatum by 50%. The affinity of [3H]N-0437 for dopamine receptors was reduced by half. 6-Hydroxydopamine lesions had no measurable effect on the Bmax or on the KD. Of the physiological metal ions tested only Na+ had a significant effect on the binding. Sodium ions reduced the affinity of [3H]N-0437 for striatal receptors from 5.0 +/- 1.1 nM to 8.4 +/- 0.3 nM. In addition GTP lowered the Bmax from 1121 +/- 44 to 868 +/- 84 fmol/mg protein. The trace ions Li+ and Mn2+ had no effect at a concentration of 3.0 mM, while the exogenous ion Hg2+ at the same concentration prevented the specific binding of [3H]N-0437. Together, the results suggest that [3H]N-0437 labels both pre- and postsynaptic receptors, although postsynaptic receptors are labelled preferentially. Moreover, there is an indication that GTP shifts the affinity state of the D-2 receptor from high to low, while Na+ seems to be an allosteric inhibitor.

Beyond receptors: multiple second-messenger systems in brain

Second-messenger systems play a major role in mediating neurotransmitter actions. In recent years our understanding of the organization and function of two prominent second-messenger systems has progressed rapidly--the adenylate cyclase and phosphoinositide systems. Guanosine triphosphate-binding proteins, which are especially abundant in brain, couple transmitter receptors to the key second-messenger generating enzymes in both of these systems. Whereas activation of adenylate cyclase produces a single intracellular messenger, cyclic AMP, stimulation of the phosphoinositide system generates at least two, inositol trisphosphate and diacylglycerol. Inositol trisphosphate mobilizes calcium from intracellular stores, and diacylglycerol, like cyclic adenosine monophosphate, activates a phosphorylating enzyme, protein kinase C. These second-messenger systems are particularly enriched in the brain where they modulate many aspects of synaptic transmission.

Treatment of Parkinson's disease with agents other than levodopa and dopamine agonists: controversies and new approaches

Parkinson's disease is associated with a variety of neurotransmitter disturbances which may be further altered by its treatment with dopamine agonists. Based on this information a wide range of pharmacological approaches have been used in search of newer treatment alternatives and in hopes of reducing complications of long-term levodopa use. This paper reviews the various therapies which have had some success in the management of Parkinson's disease, other than levodopa and dopamine agonists. Special emphasis is placed on the many unresolved questions and controversies that exist in this area of neuropharmacology.

Lithium does not interact with haloperidol in the dopaminergic pathways of the rat brain

Prophylactic treatment with lithium has been reported to prevent haloperidol-induced dopamine (DA) receptor supersensitivity. If such an effect exists, then lithium may be useful in the prevention of tardive dyskinesia, which is related to the neuroleptic-induced DA hyperfunction. In the experiments reported here chronic lithium administration had no effect on DA synthesis or utilization in the nigrostriatal, mesolimbic, or mesocortical DA pathways in the rat brain. Similarly, lithium had no effect on the increase in DA metabolism induced by the acute administration of haloperidol. Also, chronic lithium treatment failed to modify the biochemical tolerance which developed after prolonged administration of the neuroleptic drug. Supersensitivity of the presynaptic DA receptors, which was induced by prolonged exposure to haloperidol, likewise was unaffected by prophylactic lithium treatment. We conclude that lithium does not affect changes in DA metabolism or receptor supersensitivity induced by haloperidol. These results do not support the use of lithium in neurological disorders that may be related to neuroleptic-induced DA receptor supersensitivity.

A review of clinical trials of lithium in neurology

Lithium has been put to clinical trials in no less than fifteen neurological disorders. They are Huntington's chorea, tardive dyskinesia, spasmodic torticollis, Tourette's syndrome, L-dopa induced hyperkinesia and the "on-off" phenomenon in parkinsonism, organic brain disorders secondary to brain-injury, drug induced delusional disorders, migraine and cluster headache, periodic hypersomnolence, epilepsy, meniere's disease and periodic hypokalemic paralysis. This paper gives a brief summary of the clinical trials with lithium salts reported in the literature. There are encouraging results on the use of lithium in cluster headaches, cyclic form of migraine and hypomanic mood disorders due to organic brain disorders. The trials with lithium and amitriptyline in tardive dyskinesia needs independent confirmation. The effect of lithium on seizure disorders needs to be addressed too.

Problems of levodopa treatment

This article reviews the side-effects of levodopa therapy in Parkinson's disease. First the pharmacokinetic aspects of levodopa are dealt with. Then the side-effects are successively discussed. Finally the therapeutic possibilities for the side-effects will be covered. An attempt has been made to give both proponents and opponents of a certain therapy their due to make it clear to the reader that for the time being uniform therapeutic recommendations are not always possible. The typical characteristics and circumstances of every individual patient should be considered before any advice can be given.

The Na,K-ATPase hypothesis for manic-depression. II. The mechanism of action of lithium

A model as to how lithium may work in the treatment and prevention of manic-depression is presented. Lithium accumulates intracellularly, and accumulates preferentially in more active neurons. Intracellular accumulation of lithium displaces intracellular sodium, which, in turn, decreases intracellular calcium. A decrease of intracellular calcium normalizes neuron activity in both mania and depression. This model is supported by the majority of clinical and experimental data.