Inhibitory effects of lithium ion on intracellular Ca2+ mobilization in the rat hippocampal slices

Effect of ouabain on calcium signaling in rodent brain: A systematic review of in vitro studies

The Na⁺/K⁺-ATPase is an integral membrane ion pump, essential to maintaining osmotic balance in cells in the presence of cardiotonic steroids; more specifically, ouabain can be an endogenous modulator of the Na⁺/K⁺-ATPase. Here, we conducted a systematic review of the in vitro effects of cardiotonic steroids on Ca²⁺ in the brain of rats and mice. Methods: The review was carried out using the PubMed, Virtual Health Library, and EMBASE databases (between 12 June 2020 and 30 June 2020) and followed the guidelines described in the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Results: in total, 829 references were identified in the electronic databases; however, only 20 articles were considered, on the basis of the inclusion criteria. The studies demonstrated the effects of ouabain on Ca²⁺ signaling in synaptosomes, brain slices, and cultures of rat and mouse cells. In addition to the well-known cytotoxic effects of high doses of ouabain, resulting from indirect stimulation of the reverse mode of the Na⁺/Ca²⁺ exchanger and increased intracellular Ca²⁺, other effects have been reported. Ouabain-mediated Ca²⁺ signaling was able to act increasing cholinergic, noradrenergic and glutamatergic neurotransmission. Furthermore, ouabain significantly increased intracellular signaling molecules such as InsPs, IP3 and cAMP. Moreover treatment with low doses of ouabain stimulated myelin basic protein synthesis. Ouabain-induced intracellular Ca²⁺ increase may promote the activation of important cell signaling pathways involved in cellular homeostasis and function. Thus, the study of the application of ouabain in low doses being promising for application in neurological diseases.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020204498, identifier CRD42020204498.

Nanoparticles of barium induce apoptosis in human phagocytes

Purpose

Nutrients and immunological factors of breast milk are essential for newborn growth and the development of their immune system, but this secretion can contain organic and inorganic toxins such as barium. Colostrum contamination with barium is an important issue to investigate because this naturally occurring element is also associated with human activity and industrial pollution. The study evaluated the administration of barium nanoparticles to colostrum, assessing the viability and functional activity of colostral mononuclear phagocytes.

Methods

Colostrum was collected from 24 clinically healthy women (aged 18–35 years). Cell viability, superoxide release, intracellular Ca²⁺ release, and phagocyte apoptosis were analyzed in the samples.

Results

Treatment with barium lowered mononuclear phagocyte viability, increased superoxide release, and reduced intracellular calcium release. In addition, barium increased cell death by apoptosis.

Conclusion

These data suggest that nanoparticles of barium in colostrum are toxic to cells, showing the importance of avoiding exposure to this element.

Voltage-dependent calcium channel and NMDA receptor antagonists augment anticonvulsant effects of lithium chloride on pentylenetetrazole-induced clonic seizures in mice

Although lithium is still a mainstay in the treatment of bipolar disorder, its underlying mechanisms of action have not been completely elucidated. Several studies have shown that lithium can also modulate seizure susceptibility in a variety of models. In the present study, using a model of clonic seizures induced with pentylenetetrazole (PTZ) in male Swiss mice, we investigated whether there is any interaction between lithium and either calcium channel blockers (CCBs: nifedipine, verapamil, and diltiazem) or N-methyl-D-aspartate (NMDA) receptor antagonists (ketamine and MK-801) in modulating seizure threshold. Acute lithium administration (5-100mg/kg, ip) significantly (P<0.01) increased seizure threshold. CCBs and NMDA receptor antagonists also exerted dose-dependent anticonvulsant effects on PTZ-induced seizures. Noneffective doses of CCBs (5mg/kg, ip), when combined with a noneffective dose of lithium (5mg/kg, ip), exerted significant anticonvulsant effects. Moreover, co-administration of a noneffective dose of either MK-801 (0.05mg/kg, ip) or ketamine (5mg/kg, ip) with a noneffective dose of lithium (5mg/kg, ip) significantly increased seizure threshold. Our findings demonstrate that lithium increases the clonic seizure threshold induced by PTZ in mice and interacts with either CCBs or NMDA receptor antagonists in exerting this effect, suggesting a role for Ca(2+) signaling in the anticonvulsant effects of lithium in the PTZ model of clonic seizures in mice.

The influence of chronic lithium administration on deafferentation-induced cellular changes in the chick cochlear nucleus

The avian brainstem serves as a useful model system to address the question of how afferent activity influences viability of target neurons. Approximately 20-30% of neurons in the chick cochlear nucleus, nucleus magnocellularis (NM) die following deafferentation (i.e. deafness produced by cochlea removal). Previous studies have identified cellular events that occur within hours following cochlea removal, which are thought to lead to the ultimate death of NM neurons. We have recently shown that chronic lithium treatment increases neuronal survival following deafferentation. To assess where in the cell death cascade lithium is having its effect, we evaluated some of the early deafferentation-induced cellular changes in NM neurons. Lithium did not affect deafferentation-induced changes that occur across the entire population of NM neurons. There were still deafferentation-induced increases in intracellular calcium concentrations and early changes in the ribosomes, as indicated by Y10b immunolabeling. Lithium did, however, affect changes that are believed to be indicative of the subpopulation of NM neurons that will eventually die. Ribosomes recovered in all of the deafferented NM neurons (as assessed by Y10b labeling) by 10 h following cochlea removal in subjects pretreated with lithium, while a subpopulation of the NM neurons in saline-treated subjects showed dramatic reduction in Y10b labeling at that time. Lithium treatment also prevented the robust upregulation of b cell leukemia/lymphoma-2 (Bcl-2) mRNA that is observed in a subpopulation of deafferented NM neurons 6 h following cochlea removal.

Effect of lithium on endothelium-dependent and neurogenic relaxation of rat corpus cavernosum: Role of nitric oxide pathway

INTRODUCTION

Some studies have reported erectile dysfunction in patients receiving lithium through a mechanism that has not yet been defined. The aim of the present study was to verify the effect of acute lithium administration on the nonadrenergic noncholinergic (NANC)- and endothelium-mediated relaxation of rat isolated corpus cavernosum.

MATERIALS AND METHODS

The isolated rat corporeal strips were precontracted with phenylephrine hydrochloride (7.5 microM) and electrical field stimulation (EFS) was applied at different frequencies (2, 5, 10, and 15 Hz) to obtain NANC-mediated relaxation or relaxed by adding cumulative doses of acetylcholine (10nM-1mM) to obtain endothelium-dependent relaxation in the presence or absence of lithium (0.3, 0.5, 1, and 5mM). Also, effects of combining lithium (0.3mM) with 30 nM and 0.1 nM L-NAME (an NO synthase inhibitor) on NANC- and acetylcholine-mediated relaxation was investigated, respectively. Moreover, effects of combining lithium (1mM) with 0.1mM and 10 microM L-arginine (a precursor of NO) on NANC- and endothelium-mediated relaxation was assessed, respectively. Also, the effect of lithium (1mM) on relaxation to sodium nitroprusside (SNP; 1nM-1mM), an NO donor, was investigated.

RESULTS

The NANC-mediated relaxation was significantly (P<0.001) reduced by 1 and 5mM, but not by 0.3 and 0.5mM lithium. Lithium significantly (P<0.001) attenuated the maximum response to acetylcholine in a concentration-dependent manner. Combination of lithium (0.3mM) with 30 and 0.1 nM L-NAME, which separately had a minimum effect on NANC- and endothelium-mediated relaxation, significantly (P<0.001) reduced the NANC- and endothelium-mediated relaxation, respectively. Although L-arginine at 10 microM and 0.1mM did not alter the relaxant responses to acetylcholine and EFS, it improved the inhibition by lithium (1mM) of relaxant responses to acetylcholine and EFS, respectively. Also, SNP produced similar concentration-dependent relaxations from both groups.

DISCUSSION

Our experiments indicated that lithium likely by interfering with NO pathway in both endothelium and nitrergic nerve can result in impairment of both the endothelium- and NANC-mediated relaxation of rat corpus cavernosum.

Effect of lithium on norepinephrine metabolic pathways

We investigated lithium-induced changes in norepinephrine (NE) catabolism. NE and its major metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxyphenyl glycol (DHPG), ions such as lithium (Li(+)), magnesium (Mg(2+)), and potassium (K(+)) were measured in rat plasma and cerebral cortex using an HPLC method with electrochemical detection for amines. The results obtained with a group of rats treated by lithium chloride (2 mmol/kg/IP) were compared with a control group receiving sodium chloride (2 mmol/kg/IP). Animals were killed at different times over a period of six hours in the morning following salt administration to minimize possible chronobiological effects. There are two pathways leading to MHPG formation: way A, without DHPG, and way B, with DHPG. In plasma and cerebral cortex of lithium treated rats, way A catabolism seems to be preferential. Lithium increases Mg(2+) and K(+) plasma levels. These results suggest that lithium may increase inactivation of NE and decrease NE available for adrenergic receptors.

Effect of neonatal isolation on the noradrenergic transduction system in the rat hippocampal slice

Numerous studies suggest that early adverse experiences induce neurochemical, morphological, and functional changes in the hippocampus in adolescence and adulthood. The aim of this study was to identify the influence of neonatal isolation (NI) on noradrenaline (NA)-mediated intracellular calcium ([Ca(2+)](i)) mobilization. To measure [Ca(2+)](i), we used the Ca(2+)-sensitive dye fura-2 and analysis by fluorescence microscopy. First, we examined the contributions of adrenergic receptor subtypes to the NA-stimulated increase in [Ca(2+)](i) in the granule cell layers of the dentate gyrus (DG) and in the pyramidal cell layers of the CA3 in the hippocampus. Second, we found that the NA-stimulated [Ca(2+)](i) increment was significantly decreased in response to NI in these hippocampal regions. In addition, we examined the influence of environmental enrichment (EE) after weaning on the decrease in the NA-stimulated [Ca(2+)](i) increment induced by NI. The administration of EE reversed the influence of NI on the NA-stimulated [Ca(2+)](i) increment in the CA3 pyramidal cell layer but not in the DG granular cell layer in the hippocampus. These findings suggest that NI and EE after weaning may modulate hippocampal function by altering adrenergic receptor-mediated signal transduction during adolescence.

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.

Method for simultaneous measurement of norepinephrine, 3-methoxy-4-hydroxyphenylglycol and 3,4-dihydroxyphenylglycol by liquid chromatography with electrochemical detection: application in rat cerebral cortex and plasma after lithium chloride treatment

An assay was developed to quantify norepinephrine (NE) and its metabolites (MHPG and DHPG) by high-performance liquid chromatography with electrochemical detection method (HPLC-ECD) in brain tissue and plasma of rats treated by LiCl. Separation on C(18) column was obtained by a mobile phase consisting of 4.5% methanol in buffer (0.1 M sodium acetate, 0.2 M citric acid) containing 0.2 mM ethylenediaminetetraacetic acid disodium salt (EDTA Na(2)) and 0.4 mM sodium octylsulfate, operated at a flow rate of 0.8 ml/min. A potential of +0.78 V was applied across the working and reference electrodes of the detector. The precision was in the range 2.88-4.35% for NE, 5.94-11.0% for MHPG and 1.97-4.40% for DHPG. Accuracy was 98.8-99.3% for NE, 97.4-100% for MHPG and 96.1-101% for DHPG. The limit of detection was 0.6 ng/ml for NE, 0.5 ng/ml for MHPG and 0.2 ng/ml for DHPG. The linearity is over the range 20-60 ng/ml for NE, 7-23 ng/ml for MHPG and 6-20 ng/ml for DHPG. The assay has been applied successfully to measure simultaneously cortex and plasmas concentrations of these three catecholamines in rats.

Tumor necrosis factor induces apoptosis in hepatoma cells by increasing Ca(2+) release from the endoplasmic reticulum and suppressing Bcl-2 expression

Tumor necrosis factor (TNF) plays an import role in the control of apoptosis. The most well known apoptotic pathway regulated by TNF involves the TNFR1-associated death domain protein, Fas-associated death domain protein, and caspase-8. This study examines the mechanism of TNF-induced apoptosis in FaO rat hepatoma cells. TNF treatment significantly increased the percentage of apoptotic cells. TNF did not activate caspase-8 but activated caspase-3, -10, and -12. The effect of TNF on the expression of different members of the Bcl-2 family in these cells was studied. We observed no detectable changes in the steady-state levels of Bcl-X(L), Bax, and Bid, although TNF suppresses Bcl-2 expression. Dantrolene suppressed the inhibitory effect of TNF on Bcl-2 expression. TNF induced release of Ca(2+) from the endoplasmic reticulum (ER) that was blocked by dantrolene. Importantly, the expression of Bcl-2 blocked TNF-induced apoptosis and decreased TNF-induced Ca(2+) release. These results suggest that TNF induces apoptosis by a mechanism that involves increasing Ca(2+) release from the ER and suppression of Bcl-2 expression.

Emerging therapeutic targets in bipolar mood disorder

Bipolar mood disorder is a chronic, severe and life-threatening psychiatric illness, whose underlying pathophysiology is still obscure. Lithium is the mainstay of treatment for this illness, with robust acute antimanic and long-term prophylactic effects. Over the past decade, valproate has been another medication shown to have possibly similar mood-stabilising properties to lithium, in double-blind controlled trials. Nonetheless, among patients suffering from bipolar disorder, a substantial percentage appears to respond poorly to currently available pharmacological therapies, including lithium, valproate, carbamazepine and other newer compounds, clearly demonstrating that there is a substantial need for improved therapeutic agents. Very significant effort has been made in the past several years to elucidate the cellular mechanisms by which lithium and valproate produce their therapeutic effects. The available evidence points to a modulatory action of these compounds over multiple neural biochemical pathways and most investigations have found relevant actions of mood stabilisers on intracellular signal transduction mechanisms. Moreover, it has been shown in recent years that lithium and valproate lead to long-term changes in neural plasticity, with eventual neurotrophic and neuroprotective effects. Although these actions are not fully understood, stimulation of transcription factors and effects on gene expression are potentially involved. The search for the mechanisms of action of well-established mood-stabilisers has helped to reveal promising molecular targets to test novel therapeutic approaches. This review will examine the current investigations on the diverse biochemical and molecular pathways regulated by either lithium or valproate and highlight the potential cellular targets for the development of novel mood stabilisers.

Effect of lithium on superoxide production and intracellular free calcium mobilization in elastin peptide (kappa-elastin) and FMLP stimulated human PMNS. Effect of age

The effect of lithium pretreatment on superoxide anion production and intracellular free calcium levels was investigated in polymorphonuclear leukocytes (PMN) from middle-aged and old individuals after stimulation by elastin peptides or FMLP. K-elastin (KE) significantly stimulated the production of superoxide anion by PMNs from middle-aged subjects, while this stimulation decreased with age and was absent in PMNs of elderly arteriosclerotic patients. Li pretreatment slightly increased this stimulating effect of KE in PMNs from middle-aged subjects and elderly arteriosclerotic patients, while slightly decreased in healthy elderly subjects. Moreover, Li was able to increase superoxide anion production even in the absence of KE, but this effect decreased also in PMNs of healthy and arteriosclerotic elderly patients. FMLP significantly increased superoxide anion production in all age-groups, but this effect was further amplified by Li only in PMNs of middle-aged subjects. In aged individuals Li pretreatment slightly decreased the effect of FMLP and had no effect in arteriosclerotic patients. Ca-mobilization induced by KE was inhibited by Li pretreatement in each age group. This inhibition by Li was much weaker in FMLP-stimulated PMNs. Li pretreatment did however modify the shape of the Ca-transient curves in FMLP stimulated leukocytes suggesting a qualitative modification of ion channel regulation. No such shape change of Ca-transient curves was observed after KE stimulation of Li pretreated PMNs. It appears that the regulation of these two receptors is differently affected by Li treatment.

Neuronal apoptosis induced by pharmacological concentrations of 3-hydroxykynurenine: characterization and protection by dantrolene and Bcl-2 overexpression

We have studied neurotoxicity induced by pharmacological concentrations of 3-hydroxykynurenine (3-HK), an endogenous toxin implicated in certain neurodegenerative diseases, in cerebellar granule cells, PC12 pheochromocytoma cells, and GT1-7 hypothalamic neurosecretory cells. In all three cell types, the toxicity was induced in a dose-dependent manner by 3-HK at high micromolar concentrations and had features characteristic of apoptosis, including chromatin condensation and internucleosomal DNA cleavage. In cerebellar granule cells, the 3-HK neurotoxicity was unaffected by xanthine oxidase inhibitors but markedly potentiated by superoxide dismutase and its hemelike mimetic, MnTBAP [manganese(III) tetrakis(benzoic acid)porphyrin chloride]. Catalase blocked 3-HK neurotoxicity in the absence and presence of superoxide dismutase or MnTBAP. The formation of H(2)O(2) was demonstrated in PC12 and GT1-7 cells treated with 3-HK, by measuring the increase in the fluorescent product, 2',7'-dichlorofluorescein. In both PC12 and cerebellar granule cells, inhibitors of the neutral amino acid transporter that mediates the uptake of 3-HK failed to block 3-HK toxicity. However, their toxicity was slightly potentiated by the iron chelator, deferoxamine. Taken together, our results suggest that neurotoxicity induced by pharmacological concentrations of 3-HK in these cell types is mediated primarily by H(2)O(2), which is formed most likely by auto-oxidation of 3-HK in extracellular compartments. 3-HK-induced death of PC12 and GT1-7 cells was protected by dantrolene, an inhibitor of calcium release from the endoplasmic reticulum. The protection by dantrolene was associated with a marked increase in the protein level of Bcl-2, a prominent antiapoptotic gene product. Moreover, overexpression of Bcl-2 in GT1-7 cells elicited by gene transfection suppressed 3-HK toxicity. Thus, dantrolene may elicit its neuroprotective effects by mechanisms involving up-regulation of the level and function of Bcl-2 protein.

Modulation of carbachol-stimulated AP-1 DNA binding activity by therapeutic agents for bipolar disorder in human neuroblastoma SH-SY5Y cells

Lithium, carbamazepine and sodium valproate are mood stabilizers used in the treatment of bipolar disorder, and although their mechanisms of action remain unknown, signal transduction systems and the associated modulation of gene expression may constitute significant actions. We examined if acute or chronic treatments with these agents modulated the activation of the AP-1 transcription factor or the increased intracellular calcium levels in human neuroblastoma SH-SY5Y cells caused by stimulation with carbachol. AP-1 activation stimulated by carbachol was reduced by pretreatment for 1 h, 24 h or 7 days with 1 mM lithium by 15%, 37%, and 60%, respectively, and with 0.05 mM carbamazepine by 3%, 21%, and 46%, respectively, but not by pretreatment with 0.5 mM sodium valproate. AP-1 DNA binding activity stimulated by carbachol or by phorbol ester-induced activation of protein kinase C was inhibited by the protein kinase C inhibitor Ro31-8220, but phorbol ester-stimulated AP-1 activation was unaltered by 7-day pretreatments with lithium or carbamazepine. Activation of AP-1 by carbachol was dependent on calcium, as it was inhibited by treatment with the extracellular calcium chelator EGTA, the intracellular calcium chelator BAPTA-AM, and the calcium/calmodulin kinase II inhibitor KN62. Pretreatment for 7 days with lithium or carbamazepine had no significant effect on carbachol-stimulated increases in intracellular calcium levels, but reduced the stimulation of AP-1 by the calcium ionophore ionomycin by 30% to 40%. Thus, chronic treatment with the antibipolar agents lithium and carbamazepine attenuates carbachol-stimulated AP-1 DNA binding activity, and these agents preferentially inhibit signaling cascades activated by the calcium rather than the protein kinase C arm of the phosphoinositide signaling pathway.

AP-1 and NF-kappaB stimulated by carbachol in human neuroblastoma SH-SY5Y cells are differentially sensitive to inhibition by lithium

In order to identify potential actions of lithium, the primary therapeutic agent for bipolar affective disorder, on processes regulating gene expression, its effects on two transcription factors, AP-1 and NF-kappaB, were measured in human neuroblastoma SH-SY5Y cells. The cholinergic agonist carbachol concentration-dependently stimulated AP-1 (EC50 = 2 microM) and NF-kappaB (EC50 = 14 microM). Pretreatment for 24 h with a therapeutically relevant concentration of lithium (1 mM) substantially inhibited (30-35%) carbachol-stimulation AP-1 but not NF-kappaB. Inhibition of carbachol-induced AP-1 was directly related to the concentration of lithium (1-20 mM). Besides being differentially sensitive to inhibition by lithium, activation of AP-1 and NF-kappaB demonstrated different carbachol EC50 concentrations, and carbachol-induced activation of AP-1, but not NF-kappaB, was inhibited by treating cells with Ni2+, which blocks receptor-mediated calcium influx. These findings demonstrate that one mechanism by which lithium can influence the expression of specific genes is through the selective modulation of signaling processes which emanate from cholinergic receptor stimulation.

Chronic treatment with antidepressants, verapamil, or lithium inhibits the serotonin-induced intracellular calcium response in individual C6 rat glioma cells

The effects of chronic treatment with antidepressants, verapamil, or lithium on serotonin (5-HT)-induced Ca2+ increase were investigated in single C6BU-1 glioma cells with digital imaging microscopy. Clomipramine and citalopram, at a concentration of 100 nM, decreased the peak values of 5-HT-induced [Ca2+]i changes. Verapamil (100 nM), a calcium antagonist, and lithium (1 mM) also inhibited the peak amplitudes in the same way. The present findings suggest that chronic treatment with antidepressants, verapamil, or lithium, at therapeutic concentrations, have the common action of inhibiting 5-HT-mediated [Ca2+]i increase.