Effects of lithium on platelet ionic intracellular calcium concentration in patients with bipolar (manic-depressive) disorder and healthy controls

The Changes of Blood and CSF Ion Levels in Depressed Patients: a Systematic Review and Meta-analysis

Micronutrient deficiencies and excesses are closely related to developing and treating depression. Traditional and effective antidepressants include tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and lithium. There is no consensus on the fluctuation of zinc (Zn2+), magnesium (Mg2+), calcium (Ca2+), copper (Cu2+), iron (Fe2+), and manganese (Mn2+) ion levels in depressed individuals before and after therapy. In order to determine whether there were changes in blood and cerebrospinal fluid (CSF) levels of these ions in depressed patients compared with healthy controls and depressed patients treated with TCAs, SSRIs, or lithium, we applied a systematic review and meta-analysis. Using the Stata 17.0 software, we performed a systematic review and meta-analysis of the changes in ion levels in human samples from healthy controls, depressive patients, and patients treated with TCAs, SSRIs, and lithium, respectively. By searching the PubMed, EMBASE, Google Scholar, Web of Science, China National Knowledge Infrastructure (CNKI), and WAN FANG databases, 75 published analyzable papers were chosen. In the blood, the levels of Zn2+ and Mg2+ in depressed patients had decreased while the Ca2+ and Cu2+ levels had increased compared to healthy controls, Fe2+ and Mn2+ levels have not significantly changed. After treatment with SSRIs, the levels of Zn2+ and Ca2+ in depressed patients increased while Cu2+ levels decreased. Mg2+ and Ca2+ levels were increased in depressed patients after Lithium treatment. The findings of the meta-analysis revealed that micronutrient levels were closely associated with the onset of depression and prompted more research into the underlying mechanisms as well as the pathophysiological and therapeutic implications.

Cellular calcium in bipolar disorder: systematic review and meta-analysis

Calcium signalling has long been implicated in bipolar disorder, especially by reports of altered intracellular calcium ion concentrations ([Ca²⁺]). However, the evidence has not been appraised critically. We carried out a systematic review and meta-analysis of studies of cellular calcium indices in bipolar disorder. 2281 records were identified and 117 screened, of which 32 were eligible and 21 were suitable for meta-analyses. The latter each involved up to 642 patients and 404 control subjects. We found that basal free intracellular [Ca²⁺] is increased in bipolar disorder, both in platelets and in lymphocytes. The effect size is 0.55, with an estimated elevation of 29%. It is observed in medication-free patients. It is present in mania and bipolar depression, but data are equivocal for euthymia. Cells from bipolar disorder individuals also show an enhanced [Ca²⁺] response to stimulation with 5-HT or thrombin, by an estimated 25%, with an effect size of 0.63. In studies which included other diagnoses, intracellular basal [Ca²⁺] was higher in bipolar disorder than in unipolar depression, but not significantly different from schizophrenia. Functional parameters of cellular Ca²⁺ (e.g. calcium transients), and neuronal [Ca²⁺], have been much less investigated, and no firm conclusions can be drawn. In summary, there is a robust, medium effect size elevation of basal and stimulated free intracellular [Ca²⁺] in bipolar disorder. The results suggest altered calcium functioning in the disorder, and encourage further investigations into the underlying mechanisms, and the implications for pathophysiology and therapeutics.

Chronic LiCl pretreatment suppresses thrombin-stimulated intracellular calcium mobilization through TRPC3 in astroglioma cells

OBJECTIVES

Transient receptor potential canonical type 3 (TRPC3) channels are activated in B lymphoblast cell lines from patients with bipolar disorder (BD), and its expression is reduced by chronic lithium treatment, implicating TRPC3 in the intracellular calcium (Ca²⁺ ) dyshomeostasis of BD. Thrombin, via a protease-activated receptor, moderates Ca²⁺ signaling and TRPC3 in astrocytes, and also cell proliferation. We examined whether lithium pretreatment attenuates thrombin-stimulated TRPC3 expression and function in astrocytes, and levels of the calcium-binding peptide, S100B, which is expressed mainly in these cells.

METHODS

Human astroglioma, U-87MG, cells were pretreated with 1 mmol L^-1 LiCl for 1 day (acute), 3 days (subacute), and 7 days (chronic). To examine the role of TRPC3, genetically stable knockdown TRPC3 cells (TRPC3^Low cells) were constructed using U-87MG cells. Thrombin (2.0 U/mL)-stimulated Ca²⁺ mobilization was measured by ratiometric fluorimetry. Changes in TRPC3 and S100B expression levels were determined by quantitative reverse transcription-polymerase chain reaction and immunoblotting, respectively. Cell proliferation was also measured using the WST-8 assay.

RESULTS

In this cell model, thrombin-stimulated Ca²⁺ mobilization, and both TRPC3 and S100B expression were suppressed by chronic LiCl pretreatment and the knockdown of TRPC3. Additionally, cell proliferation was attenuated in TRPC3^Low cells, compared with the negative control vector-transfected cell.

CONCLUSIONS

The reduced Ca²⁺ mobilization and S100B expression levels following chronic LiCl pretreatment and in TRPC3^Low cells support the notion that TRPC3 modulates S100B expression and is the target of the LiCl effect. Downregulation of TRPC3 may be an important mechanism by which lithium ameliorates pathophysiological intracellular Ca²⁺ disturbances as observed in BD, accounting, in part, for its mood-stabilizing effects.

Translating neurotrophic and cellular plasticity: from pathophysiology to improved therapeutics for bipolar disorder

OBJECTIVE

Bipolar disorder (BD) likely involves, at a molecular and cellular level, dysfunctions of critical neurotrophic, cellular plasticity and resilience pathways and neuroprotective processes. Therapeutic properties of mood stabilizers are presumed to result from a restoration of the function of these altered pathways and processes through a wide range of biochemical and molecular effects. We aimed to review the altered pathways and processes implicated in BD, such as neurotrophic factors, mitogen-activated protein kinases, Bcl-2, phosphoinositol signaling, intracellular calcium and glycogen synthase kinase-3.

METHODS

We undertook a literature search of recent relevant journal articles, book chapter and reviews on neurodegeneration and neuroprotection in BD. Search words entered were 'brain-derived neurotrophic factor,''Bcl-2,''mitogen-activated protein kinases,''neuroprotection,''calcium,''bipolar disorder,''mania,' and 'depression.'

RESULTS

The most consistent and replicated findings in the pathophysiology of BD may be classified as follows: i) calcium dysregulation, ii) mitochondrial/endoplasmic reticulum dysfunction, iii) glial and neuronal death/atrophy and iv) loss of neurotrophic/plasticity effects in brain areas critically involved in mood regulation. In addition, the evidence supports that treatment with mood stabilizers; in particular, lithium restores these pathophysiological changes.

CONCLUSION

Bipolar disorder is associated with impairments in neurotrophic, cellular plasticity and resilience pathways as well as in neuroprotective processes. The evidence supports that treatment with mood stabilizers, in particular lithium, restores these pathophysiological changes. Studies that attempt to prevent (intervene before the onset of the molecular and cellular changes), treat (minimize severity of these deficits over time), and rectify (reverse molecular and cellular deficits) are promising therapeutic strategies for developing improved treatments for bipolar disorder.

Mitochondrially mediated plasticity in the pathophysiology and treatment of bipolar disorder

Bipolar disorder (BPD) has traditionally been conceptualized as a neurochemical disorder, but there is mounting evidence for impairments of cellular plasticity and resilience. Here, we review and synthesize the evidence that critical aspects of mitochondrial function may play an integral role in the pathophysiology and treatment of BPD. Retrospective database searches were performed, including MEDLINE, abstract booklets, and conference proceedings. Articles were also obtained from references therein and personal communications, including original scientific work, reviews, and meta-analyses of the literature. Material regarding the potential role of mitochondrial function included genetic studies, microarray studies, studies of intracellular calcium regulation, neuroimaging studies, postmortem brain studies, and preclinical and clinical studies of cellular plasticity and resilience. We review these data and discuss their implications not only in the context of changing existing conceptualizations regarding the pathophysiology of BPD, but also for the strategic development of improved therapeutics. We have focused on specific aspects of mitochondrial dysfunction that may have major relevance for the pathophysiology and treatment of BPD. Notably, we discuss calcium dysregulation, oxidative phosphorylation abnormalities, and abnormalities in cellular resilience and synaptic plasticity. Accumulating evidence from microarray studies, biochemical studies, neuroimaging, and postmortem brain studies all support the role of mitochondrial dysfunction in the pathophysiology of BPD. We propose that although BPD is not a classic mitochondrial disease, subtle deficits in mitochondrial function likely play an important role in various facets of BPD, and that enhancing mitochondrial function may represent a critical component for the optimal long-term treatment of the disorder.

Role of mitochondrial DNA in calcium signaling abnormality in bipolar disorder

Altered intracellular calcium levels are a consistent finding in studies of bipolar disorder, and recent studies point to the role of mitochondrial dysfunction, leading to the possibility that mitochondrial calcium dysregulation is involved in the pathophysiology of the disease. Although the mitochondrion is a key organelle for calcium accumulation, initial calcium signaling studies in bipolar disorder did not focus on the role of mitochondria. Later, neuroimaging and molecular genetic studies suggested the possibility that altered mitochondrial calcium regulation due to mitochondrial DNA (mtDNA) polymorphisms/mutations might be involved in the pathophysiology of bipolar disorder. Recent studies show that certain mtDNA polymorphisms alter mitochondrial calcium levels. Mutant mtDNA polymerase (Polg) transgenic mice carrying mtDNA mutations in forebrain cells show an increased calcium uptake rate in isolated mitochondria. This was found to be mediated by downregulation of cyclophilin D, a component of the mitochondrial permeability transition pore. In addition, agonist-stimulated calcium response is attenuated in hippocampal neurons of these transgenic mice. The finding that mtDNA polymorphisms and mutations affect mitochondrial calcium regulation supports the idea that mitochondrial calcium dysregulation may be involved in the pathophysiology of bipolar disorder. In this review, the history and recent findings of studies elucidating the role of mitochondrial calcium signaling in bipolar disorder are summarized.

Chronic lithium treatment of B lymphoblasts from bipolar disorder patients reduces transient receptor potential channel 3 levels

Chronic lithium treatment of B-lymphoblast cell lines (BLCLs) from bipolar-I disorder (BD-I) patients and healthy subjects ex vivo attenuates agonist- and thapsigargin-stimulated intracellular calcium (Ca(2+)) responses. As these findings suggest that chronic lithium treatment modifies receptor (ROCE) and/or store-operated Ca(2+) entry (SOCE) mechanisms, we determined whether chronic lithium treatment of BLCLs modified the expression of two members of the transient receptor potential channels (TRPC1 & 3), which participate in ROCE/SOCE. Chronic lithium treatment significantly reduced BLCL TRPC3 immunoreactivity (repeated-measures ANOVA, P=0.00005), with interaction effects of diagnosis (P=0.037) and sex (P=0.040). The lithium-induced decrease was greatest in BLCLs from female BD-I patients compared with those from healthy females (-27%) and with vehicle-treated BLCLs from female BD-I patients (-33%). However, lithium treatment did not affect TRPC1 and 3 mRNA levels, and TRPC1 immunoreactivity. Downregulation of TRPC3 may be an important mechanism by which lithium ameliorates pathophysiological Ca(2+) disturbances as observed in BD.

Chronic lithium treatment attenuates intracellular calcium mobilization

Elevated basal intracellular calcium (Ca(2+)) levels ([Ca(2+)](B)) in B lymphoblast cell lines (BLCLs) from bipolar I disorder (BD-I) patients implicate altered Ca(2+) homeostasis in this illness. Chronic lithium treatment affects key proteins modulating intracellular Ca(2+) signaling. Thus, we sought to determine if chronic exposure to therapeutic lithium concentrations also modifies intracellular Ca(2+) homeostasis in this surrogate cellular model of signal transduction disturbances in BD. BLCLs from BD-I (N=26) and healthy subjects (N=17) were regrown from frozen stock and incubated with 0.75 mM lithium or vehicle for 24 h (acute) or 7 days (chronic). [Ca(2+)](B), lysophosphatidic acid (LPA)-stimulated Ca(2+) mobilization ([Ca(2+)](S)), and thapsigargin-induced store-operated Ca(2+) entry (SOCE) were determined using ratiometric fluorometry with Fura-2. Compared with vehicle, chronic lithium exposure resulted in significantly higher [Ca(2+)](B) (F=8.47; p=0.006) in BLCLs from BD-I and healthy subjects. However, peak LPA-stimulated [Ca(2+)](S) and SOCE were significantly reduced (F=11.1, p=0.002 and F=8.36, p=0.007, respectively). Acute lithium exposure did not significantly affect measured parameters. In summary, the effect of chronic lithium to elevate [Ca(2+)](B) in BLCLs while attenuating both receptor-stimulated and SOCE components of intracellular Ca(2+) mobilization in BLCLs suggests that modulation of intracellular Ca(2+) homeostasis may be important to the therapeutic action of lithium.

The platelet window: examining receptor regulated second messenger processes in psychosis and depression

Peripheral markers of psychiatric illness provide a potentially important window into the pathophysiology of a number of psychiatric illnesses. Direct access to pathophysiological processes is fraught with difficulty. However, receptor-regulated second messenger-mediated calcium shifts are an accessible and practical method by which to examine changes in a clinical population. This is possible because platelets and neurons share some physiological features. The platelet intracellular calcium response to receptor stimulation has previously been used as a peripheral marker of psychiatric illness across a range of neurotransmitters, including serotonin, dopamine and glutamate. This review considers the specificity and selectivity of this response and its use in psychotic and mood disorders.

Calcium homeostasis in long-term lithium-treated women with bipolar affective disorder

The authors investigated the effect of long-term lithium administration on intracellular calcium mobilization. The subjects were 13 women with bipolar affective disorder stabilized on lithium and 12 matched healthy controls. Total and ionized serum calcium, intracellular calcium ion concentration, plasma parathyroid hormone (PTH) and tyrotropin (TSH), serum electrolytes and cyclic AMP (cAMP) activity in platelets were measured. The serum electrolytes sodium, potassium and creatinine and plasma PTH and TSH were all within normal ranges in patients and controls and no differences were found between the two groups. No difference was found in basal and prostaglandin E1 (PGE1)-stimulated cAMP generation in platelets between patients and controls. However, total serum calcium and ionized serum calcium levels were higher in patients than in controls and there was a significant correlation between these two measures. In the patient group, serum lithium concentration correlated positively with stimulated levels of intracellular calcium in platelets. In the present study, no distinct hyperparathyroidism was found in lithium-treated patients. However, our findings indicate that lithium administration affects calcium metabolism in patients with bipolar affective disorder inducing mild hypercalcemia and a dose-dependent normalized calcium mobilization. Furthermore, our results did not support the hypothesis that lithium's primary site of action in bipolar illness may be on signal transduction mechanisms.

The neurobiology of bipolar disorder: focus on signal transduction pathways and the regulation of gene expression

OBJECTIVE

This article presents an overview of signal transduction pathways and reviews the research undertaken to study these systems in clinically relevant samples from patients with bipolar disorder (BD).

METHOD

We reviewed the published findings from studies of postmortem brain tissue and blood samples from patients with BD.

RESULTS

Although the exact biochemical abnormalities have yet to be identified, the presented findings strongly suggest that BD may be due, at least in part, to abnormalities in signal transduction mechanisms. In particular, altered levels or function, or both, of G-protein alpha subunits and effector molecules such as protein kinase A (PKA) and protein kinase C (PKC) have consistently been associated with BD both in peripheral cells and in postmortem brain tissue, while more recent studies implicate disruption in novel second-messenger cascades, such as the ERK/MAPK pathway.

CONCLUSIONS

Despite the difficulties inherent in biochemical studies of clinically relevant tissue samples, numerous investigations have illuminated the signal transduction mechanisms in patients with BD. These studies also suggest that BD may be due to the interaction of many abnormalities. In this context, novel techniques enabling the study of gene expression promise to assist in untangling these complex interactions, through visualizing the end result of these changes at the level of gene transcription.

Rapid cycling bipolar disease: new concepts and treatments

Having been recognized by Kraeplin at the beginning of the 20th century, rapid cycling was first described as a specific entity by Dunner et al. in 1974. The prevalence of rapid cycling ranges from 12% to 20% in patients with bipolar disorder who are not selected for a high rate of cycling.

Lithium chloride inhibits thrombin-induced intracellular calcium mobilization in C6 rat glioma cells

In this study, the authors have demonstrated the effect of lithium, a typical mood stabilizer, on thrombin-evoked Ca2+ mobilization in C6 cells to elucidate the action mechanisms of the drug. Thrombin-induced Ca2 mobilization was reduced 24 hr after 1 or 10 mM lithium chloride (LiCl) pretreatment. The Ca2+ rise was reduced in a time-dependent manner, and the significant inhibition was observed 9 hr pretreatment with 10 mM LiCl. On the other hand, pretreatment of the cells with 10 mM LiCl for 24 hr did not alter the amount of Galphaq/11 significantly. Pretreatment with 10 mM LiCl for 24 hr failed to reduce the 5-HT-induced Ca2+ mobilization or to affect the desensitization of the 5-HT signal. Finally, thrombin-elicited Ca2+ rise was markedly inhibited in the presence of 0.05 U/ml plasmin, however, the Ca2+ rise was not further attenuated in the presence of plasmin in C6 cells pretreated with LiCl for 24 hr. These results indicate that pretreatment with LiCl attenuated thrombin-evoked intracellular Ca2+ mobilization in plasmin sensitive manner in C6 rat glioma cells. Thus, it is important to investigate the effect of lithium on thrombin-induced cellular responses to clarify the action mechanism of lithium in relation to some abnormality in thrombin-evoked Ca2+ rise observed in bipolar disorders.

Serotonin stimulation of calcium mobilisation in human platelets: choice of units of measurement, effects of age and tobacco use, and correlation with serotonin2A receptor density

The calcium responses to serotonin and thrombin, as assessed using the fluorescent indicator Fura-2, have been investigated in platelets taken from 59 non-smokers and 17 smokers. The peak responses above baseline, calculated either as fluorescence ratios or calibrated calcium concentrations, were in the order of magnitude thrombin 520 mU/ml > thrombin 52 mU/ml >> serotonin 1 micromol/l approximately serotonin 100 micromol/l. Multiple regression analyses indicated that the responses to 1 micromol/l serotonin, but not the responses to thrombin, were significantly correlated with the serotonin2A receptor density measured using [3H]LSD as radioligand. No effects of age, gender, smoking habit or the time of year of sampling were seen on the calcium responses to serotonin and thrombin. It is concluded that cellular processes distal to the serotonin2A receptor recognition site may compensate to some extent for the large differences in recognition site expression, thus underlining the importance of providing a functional correlate in addition to [3H]LSD binding site densities when studying platelet serotonin2A receptors in neuropsychiatric disorders. The measurement of Ca2+ responses to serotonin provides a useful such functional correlate.

Elevated basal and thapsigargin-stimulated intracellular calcium of platelets and lymphocytes from bipolar affective disorder patients measured by a fluorometric microassay

BACKGROUND

A number of investigators have reported finding elevated basal and stimulated intracellular calcium levels in the platelets or lymphocytes of bipolar disorder patients.

METHODS

Intracellular calcium was measured by a micro fura-2 fluorometric method in the platelets and lymphocytes of 30 affective disorder patients and 14 control subjects.

RESULTS

We observed significantly elevated basal calcium concentrations in bipolar patient platelets and lymphocytes compared to control subjects. Bipolar patient platelet calcium responses to thrombin, serotonin, and thapsigargin were also significantly greater than control subjects. The peak calcium levels of lymphocytes of bipolar patients were greater than control subjects only when stimulated by thapsigargin. There were significant differences between bipolar and unipolar patients in basal and thapsigargin-stimulated calcium measures but not between bipolar I and bipolar II patients. Unmedicated versus medicated calcium measures were not significantly different. We also found little correlation between calcium measures and the severity of mood rating.

CONCLUSIONS

Using this method, we were able to confirm and extend the work of others, indicating altered intracellular calcium homeostasis in the blood cells of bipolar disorder patients. In addition, our data suggest that storage operated calcium channels may be the source of the elevated intracellular calcium in platelets and lymphocytes of bipolar patients.

Competition between Li+ and Mg2+ in neuroblastoma SH-SY5Y cells: a fluorescence and 31P NMR study

Because Mg2+ and Li+ ions have similar chemical properties, we have hypothesized that Li+/Mg2+ competition for Mg2+ binding sites is the molecular basis for the therapeutic action of lithium in manic-depressive illness. By fluorescence spectroscopy with furaptra-loaded cells, the free intracellular Mg2+ concentration within the intact neuroblastoma cells was found to increase from 0. 39 +/- 0.04 mM to 0.60 +/- 0.04 mM during a 40-min Li+ incubation in which the total intracellular Li+ concentration increased from 0 to 5.5 mM. Our fluorescence microscopy observations of Li+-free and Li+-loaded cells also indicate an increase in free Mg2+ concentration upon Li+ incubation. By 31P NMR, the free intracellular Mg2+ concentrations for Li+-free cells was 0.35 +/- 0. 03 mM and 0.80 +/- 0.04 mM for Li+-loaded cells (final total intracellular Li+ concentration of 16 mM). If a Li+/Mg2+ competition mechanism is present in neuroblastoma cells, an increase in the total intracellular Li+ concentration is expected to result in an increase in the free intracellular Mg2+ concentration, because Li+ displaces Mg2+ from its binding sites within the nerve cell. The fluorescence spectroscopy, fluorescence microscopy, and 31P NMR spectroscopy studies presented here have shown this to be the case.

Intracellular calcium signaling systems in the pathophysiology of affective disorders

In this paper, we show the importance of intracellular calcium (Ca2+) signaling systems in the pathophysiology of mood disorders based on our recent work. Patients with affective disorders appear to have an enhanced intracellular Ca2+ rise in response to serotonin. We have observed effects of antidepressant drugs on intracellular Ca2+ signaling in rat cultured neuronal cells and glioma cells, and found that acute application of several classes of antidepressant drugs inhibited intracellular Ca2+ signaling and Ca2+-related signaling. It is important to investigate the role of intracellular Ca2+ signaling system for an understanding of the pathophysiology of affective disorders.

Calibration of Fura-2 signals introduces errors into measurement of thrombin-stimulated calcium mobilisation in human platelets

The intracellular calcium indicator dye Fura-2 has been widely used for the study of human platelet thrombin receptor-mediated calcium mobilisation in disease states. In general, authors (a) use a Fura-2/AM concentration of 2-3 mumol/l and (b) calibrate fluorescence signals on the basis of maximum and minimum ratios of fluorescence (Rmax and Rmin) and the ratio of the calcium-free and calcium-bound fluorescence at an excitation wavelength of 380 nm ("C2/B2"). In the present study, it is found (a) that a greater peak response to thrombin is seen when 1 mumol/l Fura-2/AM rather than 2 or 3 mumol/l is used; and (b) that calibration leads to a poorer test-retest reliability and in general a greater variability of the obtained calcium signal than when the simple measurement of the 340 nm/380 nm fluorescence ratio is used. It is suggested that this poor variability is due to the presence of an extracellular factor that can quench the Fura-2 signal once the platelets have been permeabilised by detergent treatment. Consistent with this, addition of bovine serum albumin to the assay medium has no significant effect on the fluorescence ratio response to thrombin, but greatly increases the observed calibrated calcium signal.

Antipsychotic drugs block IP3-dependent Ca(2+)-release from rat brain microsomes

Cellular Ca(2+)-dysregulation has been proposed as an important mechanism in certain diseases such as bipolar affective disorder (BPAD) and malignant hyperthermia. Recently it has been found that in BPAD, the plasma membrane Ca(2+)-channel blockers verapamil and nimodipine are useful substitutes in Li(+)-treatable patients. We have investigated the effects of these drugs and the antipsychotic drugs (clozapine, fluspirilene, and haloperidol) on IP3-induced Ca(2+)-release from Ca(2+)-loaded rat brain microsomes. In the presence of either the Ca(2+)-channel blockers or the neuroleptic drugs, Ca(2+)-release was blocked in a dose-dependent fashion. For the neuroleptics, the EC50 ranged from 22 microM for fluspirilene to 145 microM for haloperidol. The EC50 for nimodipine was 160 microM and 450 microM for verapamil. Carbamazapine and valproic acid, anticonvulsants recently used for treating BPAD, were relatively ineffective, as were various haloperidol metabolites. The research described in this paper establishes for the first time that antipsychotic drugs, as well as certain Ca(2+)-channel blockers, directly block the IP3-induced Ca(2+)-release in a rat brain microsome assay.

Combined treatment with lithium and nimodipine in a bipolar I manic syndrome

1. The benefit of a combined treatment with the calcium antagonist nimodipine and lithium in a bipolar I disorder (currently manic, DSM IV 296.44, ICD 10 F 31.1) was explored and documented in a longitudinal single case study. 2. Nimodipine (270 mg/d) was added to lithium (900 mg/d), substituting for previously administered neuroleptics, in an up to then unsatisfactorily treated manic patient. 3. A clear-cut improvement in the patient's condition was achieved within a fortnight, and lasted over the continuation period of this drug regimen. This combined treatment was discontinued after eight weeks and lithium alone was then administered. Within three months another manic episode appeared. 4. Side-effects and changes of lithium blood levels were not observed during the combined treatment with nimodipine and lithium. 5. Further research on the benefits of adding a calcium antagonist, instead of neuroleptics, to lithium therapy for bipolar manic disorder patients who do not respond sufficiently to lithium is recommended. In addition, the benefits of a long term prophylaxis of nimodipine alone or in combination with lithium should be evaluated in those bipolar patients who still show a high relapse frequency on lithium alone.

Resting and thrombin-stimulated cytosolic calcium in platelets of patients with alcoholic withdrawal, bipolar manic disorder and chronic schizophrenia

Cytosolic calcium concentration ([Ca2+]i) in platelets during resting state and when stimulated by thrombin were measured in 7 alcoholic dependent patients in the state of withdrawal (AW) who were receiving diazepam, 7 bipolar manic patients (BM) who were receiving haloperidol, 15 drug free chronic schizophrenic patients (CS) and 26 normal controls (NC). Resting [Ca2+]i in these groups were quite similar at (mean +/- SEM) 112 +/- 20 nM, 127 +/- 18 nM, 103 +/- 16 nM and 106 +/- 8 nM respectively. Increase in platelet [Ca2+]i in response to 0.1 U/ml thrombin was expressed as delta[Ca2+]i and its percentage over resting [Ca2+]i as %[Ca2+]i. Both delta[Ca2+]i and %[Ca2+]i were significantly higher (p = 0.006 and 0.0045 respectively, ANOVA, Waller-Duncan) in AW (433 +/- 71 nM, 417 +/- 58%) than the other groups: NC (223 +/- 25 nM, 225 +/- 23%), BM (309 +/- 38 nM, 260 +/- 31%), and CS (261 +/- 34 nM, 280 +/- 29%) respectively. In vitro incubation of platelets from NC with diazepam or haloperidol did not affect the resting [Ca2+]i and %[Ca2+]i. The enhanced [Ca2+]i response to thrombin in platelets of AW is unlikely to be due to diazepam. It may indicate an abnormality in platelets during the withdrawal phase. Treatment with haloperidol resulted in slightly higher [Ca2+]i in platelets of BM. Platelet [Ca2+]i in drug-free CS was not different from NC.

Intracellular ionized calcium and increasing doses of lithium chloride therapy in healthy Sprague-Dawley rats

The use of lithium salts in the prophylaxis and treatment of several psychiatric and neurologic disorders continues to be well accepted despite the apparent lack of understanding regarding its mode of action at the molecular level. This lack of delineation in the mechanism of action is supported by numerous conflicting publications. Despite the lack of understanding, a role for calcium in the manifestation of lithium's action is a constant singular consensus. Intracellular ionized calcium ([Ca2++]i) is involved in the proper functioning of cells because of its role in the second messenger pathway. It is therefore essential to evaluate the effect of lithium on intracellular calcium metabolism in a well-defined system. In this study, platelets loaded with Fura-2-Acetoxymethyl were used to evaluate the effect of intraperitoneally administered lithium chloride at 0, 2.5, 5.0, 7.5, and 10 mmol/kg body wt. on [Ca++]i. The results showed a slight relative increase in serum Ca++ that correlated well with the dose of LiCl administered to the rats. The baseline [Ca++]i were comparable in the study groups, but the response to thrombin stimulation was more pronounced at LiCl doses of 2.5, 5.0, and 7.5/kg body wt. compared with control and rats treated with 10 mmol LiCl/kg body wt. This finding suggests a dose-dependent response of [Ca++]i to LiCl treatment. The observation may therefore explain the variations that have been reported in [Ca++]i studies with respect to LiCl therapy using different doses.

Platelet intracellular calcium in patients with recurrent affective disorders

Forty-four subjects with a history of a major recurrent affective disorder in remission and who were either on no medication or taking a single dose of psychotropic medication were conscripted together with matched controls. The fluorescent indicator fura 2 was used to measure intracellular calcium in platelets and estimations were made of total serum and ionised calcium as well as of whole blood serotonin. Intracellular calcium was measured in the resting state as well as after stimulation with thrombin, platelet activating factor and serotonin. No significant differences were found between the 17 subjects with a diagnosis of bipolar disorder or the 27 subjects with recurrent unipolar depression and their matched controls. Intracellular calcium measures were significantly higher in the lithium treated group after stimulation with 5HT, whereas the subjects taking tricyclic antidepressants did not differ significantly from their controls on any measure. Serum calcium was found to be significantly higher in those subjects taking lithium. These findings suggest that the measurement of intracellular calcium is not a useful trait marker in affective disorders. Lithium appears to enhance the 5HT induced rise of intracellular calcium.

Different subtypes of pseudohypoparathyroidism in the same family with an unusual psychiatric presentation of the index case

A 13 year old Asian girl presenting with apparent hysterical paralysis and subsequent rapid cycling bipolar mood disorder was found to have biochemical evidence of pseudohypoparathyroidism type II. The mood disorder responded to treatment of the pseudohypoparathyroidism with a vitamin D analogue. Investigation of her parents and siblings showed phenotypes consistent with two distinct types of pseudohypoparathyroidism (type I and type II) in different family members.

Intracellular calcium signalling in peripheral cells of patients with bipolar affective disorder

Consistent with previous studies, elevated free intracellular calcium ion concentrations ([Ca2+]i) were found in blood platelets and lymphocytes of patients with mania and bipolar depression. Incubation with an ultrafiltrate of plasma from patients with bipolar illness had no effect on intracellular calcium ion concentration in platelets from normal subjects, suggesting that elevated [Ca2+]i is not due to a circulating factor. As was true in an earlier study of the effect of lithium on platelets, incubation with therapeutic levels of carbamazepine lowered [Ca2+]i in lymphocytes from affectively ill patients but not controls. Increased [Ca2+]i in peripheral cells may reflect a diffuse change in cellular homeostasis and may contribute to mixtures as well as rapid alternations of activity of affective, behavioral and physiologic systems in bipolar illness. Correction of the abnormality may at least be a marker of a relevant therapeutic action if it is not the action itself.

Preliminary controlled trial of nimodipine in ultra-rapid cycling affective dysregulation

We report the initial results of the first controlled double-blind trial of nimodipine, a calcium channel antagonist, in the acute and prophylactic treatment of patients with treatment-refractory affective dysregulation. Active drug nimodipine (A) was substituted for placebo (B) in 12 patients. Patients were studied in a B-A-B design, with 3 of the 12 patients rechallenged with active drug in a B-A-B-A design (patients 9, 10, and 11). Five of the nine patients who completed the drug trial responded. One of three patients suffering from ultra-ultra-rapid (ultradian) cycling bipolar II disorder (patient 6) showed an essentially complete response; the other two ultradian patients (patients 4 and 9) showed evidence of a partial response on manic and depressive oscillations, one of which was confirmed in a B-A-B-A design. Only one of five less rapidly, but continuously cycling patients showed an excellent response (patient 10), and this was confirmed in a B-A-B-A design. The one patient who had recurrent brief depression (patient 11) showed a complete resolution of severe depressive recurrences, with response re-confirmed in an extended prophylactic trial with a B-A-B-A design. In the eight patients who completed self-ratings, nimodipine was associated with a significant reduction in the magnitude of mood fluctuations compared with the baseline placebo condition. Further clinical study of nimodipine, a calcium channel blocker with a unique profile of behavioral and anticonvulsant properties, appears warranted in patients with treatment-refractory affective illness characterized by recurrent brief depression and ultradian cycling.

Calcium mobilization in platelets from schizophrenic and healthy subjects. Regulation by lithium and neuroleptics

Intracellular free calcium concentrations ([Ca(2+)](1)) were measured in platelets from healthy volunteers before and after adding thrombin, chlorpromazine, haloperidol and/or lithium, and in platelets from DSM-III-R diagnosed schizophrenic patients receiving neuroleptic medication. Thrombin increased [Ca(2+)]( 1) in a dose- dependent fashion. Chlorpromazine and haloperidol also mobilized Ca(2+) in a dose-dependent fashion, and augmented the response to low doses of thrombin without changing the maximal response to thrombin. The effects of all three drugs were not additive, suggesting that they affected the same intraplatelet calcium pool; most likely the dense tubular system. Lithium also increased [Ca(2+) ] but without affecting the response to thrombin, chlorpromazine or haloperidol. The effects of the latter three drugs were additive to that of lithium, suggesting that lithium was acting on a different calcium pool. The response to thrombin was significantly lower in platelets from schizophrenic patients than in platelets from healthy volunteers. Further studies are required to explore potential causes for this observation. Such causes include schizophrenia per se and chronic neuroleptic treatment.

Serotonin but not norepinephrine-induced calcium mobilization of platelets is enhanced in affective disorders

Intracellular calcium concentrations ([Ca++]i) in blood platelets from 11 depressed patients and 11 healthy controls were investigated. The resting [Ca++]i of platelets from depressed patients was 69.4 +/- 2.9 nM while that from controls was 74.6 +/- 4.0 nM. Serotonin (5-HT), at a concentration of 10 microM, increased [Ca++]i by 129.2 +/- 3.9 nM in platelets from depressed patients, which was significantly greater than that found in platelets from control subjects (105.2 +/- 6.0 nM). Norepinephrine (NE) 100 microM increased [Ca++]i by 46.1 +/- 7.1 nM in platelets from depressed patients, and by 38.6 +/- 6.1 nM in platelets from controls, respectively. These results indicate that 5-HT2 receptor function in platelets of depressed patients is enhanced, and support the hypothesis of hypersensitivity of 5-HT2 receptors in affective disorders.