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The effects of lithium in vitro and ex vivo on adenylate cyclase in brain are exerted by distinct mechanisms.

The effects of lithium on basal and forskolin-stimulated activity of adenylate cyclase in membrane preparations from cerebral cortex of the rat have been studied. Chronic treatment with lithium, yielding a level of lithium in serum of 0.71 +/- 0.18 mmol/l, reduced forskolin-stimulated activity in total homogenates but exerted no effect on the basal activity. Lithium in vitro, at 2 and 10 mM, did not influence the basal enzyme activity in membranes from either control or lithium-treated animals. The sensitivity of forskolin-stimulated adenylate cyclase to lithium in vitro was unaltered after chronic treatment and the in vitro and ex vivo effects of lithium on this parameter were additive. The inhibitory ex vivo effect of lithium was not antagonized by increasing concentrations of magnesium and the inhibitory effect of lithium ex vivo was still persistent after washing of the membranes. The present results indicate that lithium exerts its ex vivo effect on the activated cyclase, independently of the in vitro effect. Both effects may, however, contribute to the in vivo effect of lithium during chronic treatment.

Adenylyl Cyclases↗

Lithium in pigmented eye rats: effects of dose and time of day on drinking, body weight, retinal and blood distribution.

Lithium has been implicated in chronobiology (Seggie, et al., 1982, 1983). Previous work was done in Wistar rats, an Albino species, which lack the enzyme for synthesis of eye pigment. This pigment is important in regulation of light cued rhythms. The present project extends observations to Long Evans rats, a strain which has a pigmented eye. Groups of adult male rats were fed one of three diets: (1) normal laboratory chow; (2) a low lithium diet: lab chow supplemented with 30 mM/kg lithium chloride; and (3) a high lithium diet: lab chow supplemented with 50 mM/kg lithium chloride. Adult male rats were house individually with free access to diet and water under a 12 hour light/12 hour dark schedule. After six weeks on the diets, body weight, water intake, plasma, red blood cell and retinal lithium and retinal weight were measured every 4 hours throughout the 24 hour cycle following sacrifice by rapid decapitation. Plasma lithium levels on the high diet were 0.57 +/- 0.02 mEq/l and did not evidence a diurnal rhythm. Plasma lithium levels on the low diet were 0.35 +/- 0.01 mEq/l and evidenced a small, but significant diurnal rhythm with levels lowest just before darkness and normal food intake. Red blood cell lithium levels were significantly higher than plasma levels at 0.83 +/- 0.02 and 0.52 +/- 0.02 mEq/l for the high and low diets. Low diet, but not high diet red blood cells lithium levels evidenced a significant rhythm with a pattern similar to that seen in plasma lithium levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Stimulation of hypothalamic opioid peptide release by lithium is mediated by opioid autoreceptors: evidence from a combined in vitro, ex vivo study.

The effect of both chronic and acute lithium treatment on hypothalamic opioid peptides was investigated. Acute treatment with lithium was found to stimulate the release of beta-endorphin, dynorphin and Met-enkephalin from perfused rat hypothalamic slices. Application of tetrodotoxin was found to have no effect upon the stimulation indicating it to be mediated at the nerve terminal level. The release of hypothalamic opioid peptides is known to be under the chronic control of a system of inhibitory autoreceptors. Blockade of these autoreceptors with, for example, the opioid receptor antagonist naloxone causes a release of all three opioid peptides. Simultaneous addition of naloxone and lithium was found to have no additive effect on the release of any opioid, suggesting lithium acts via an inhibition of the inhibitory autoreceptor. Preincubation with pertussis toxin prevented the lithium stimulation of dynorphin and Met-enkephalin, but not beta-endorphin, release, indicating lithium interacts with a G-protein to affect the autoreceptor controlling the release of dynorphin and Met-enkephalin. Chronic treatment with lithium in vivo (10 days) had no effect on the basal release or hypothalamic content of any of the opioids, but prevented the naloxone-stimulated release of dynorphin and Met-enkephalin in vitro. Long-term treatment with lithium would thus appear to inactivate the autoreceptor(s) controlling their release. These data demonstrate a lithium-stimulated release of hypothalamic beta-endorphin, Met-enkephalin and dynorphin, apparently mediated via an inhibition of the autoreceptors controlling their release. Chronic treatment with lithium permanently inactivated the autoreceptor(s) controlling the release of dynorphin and Met-enkephalin but not beta-endorphin. Lithium would appear to mediate its effects upon Met-enkephalin and dynorphin release via an interaction with a pertussis toxin-sensitive G-protein. The mechanisms underlying its release of beta-endorphin are at present uncertain.

Animals↗

[Side effects of low serum lithium concentrations on renal, thyroid, and sexual functions in male and female rats].

The present study, carried out in rats, is a contribution to explore physiological mechanisms underlying lithium toxicity. Male and female mature rats were divided into three groups and fed on commercial pellets: group (C) was control, group (Li1) was given 2000 mg lithium carbonate/kg of food, and group (Li2) was given 4000 mg lithium carbonate/kg of food. If we take into account the BW of the rats and the quantity of food they eat every day, we can estimate that the quantities of lithium carbonate ingested per day and kilogram of BW are, respectively, for the groups Li1 and Li2, of 212 mg (5,738 mmol Li) and 323 mg (8,742 mmol Li) for the males, and about 190 mg (5,142 mmol Li) and 289 mg (7,822 mmol Li) for the females. After 7, 14, 21 and 28 days, serum concentrations of lithium, creatinine, free triiodothyronine (FT3) and thyroxine (FT4), testosterone and estradiol were measured. Attention was also paid to growth rate and a histological examination of testes or vaginal mucosa was carried out. In treated rats, a dose-dependent loss of appetite and a decrease in growth rate were observed together with polydipsia, polyuria, and diarrhoea. Lithium serum concentrations were found to increase from 0.44 mM (day 7) to 1.34 mM (day 28) in Li1 rats and from 0.66 to 1.45 mM (day 14) in Li2 rats. Treatment was stopped at day 14 in Li2 rats because of a high mortality. The significant increase of creatinine that appeared, respectively, at day 7 and 14 in Li2 and Li1 rats shows that serum lithium concentrations ranging from 0.62 to 0.75 mM were able to induce renal insufficiency, secondarily leading to a time-dependent rise in lithium serum concentrations. A significant decrease of serum thyroxine (FT4) and triiodothyronine (FT3) levels was observed for lithium concentrations ranging from: 0.66 to 0.75 mmol l(-1) (Li2 rats) to 1.27 mmol l(-1) (Li1 rats). This effect was more pronounced for FT3, suggesting a defect of FT4/FT3 conversion. Under lithium treatment, the testosterone level decreased and spermatogenesis was stopped. By contrast, in treated female rats, estradiol level was found to be increased in a dose-dependent manner and animals were blocked in the diestrus phase at day 28. These results show that lithium can rapidly induce toxic effects in the rat at concentrations used for the treatment of bipolar disorders in human.

Animals↗

Cytokine production in bipolar affective disorder patients under lithium treatment.

BACKGROUND: Our knowledge concerning immune functioning in bipolar affective disorder (BAD) is limited, while lithium's immunomodulatory effects seem multiple and conflicting. Our aim was to evaluate cytokine production and lithium's effect on it in BAD patients, using ELISPOT technique as a sensitive tool. METHODS: Cytokine (IL-2, IL-6, IL-10 and IFN-gamma) production from isolated peripheral blood lymphocytes (PBLs) was evaluated (ELISPOT technique) in 40 euthymic BAD patients under chronic lithium treatment, in 20 healthy volunteers, and in 10 never medicated BAD patients before and after the introduction of lithium therapy. In all cases, cytokine plasma levels were also measured using ELISA. RESULTS: BAD patients under chronic lithium treatment had significantly lower numbers of IL-2, IL-6, IL-10 and IFN-gamma secreting cells compared to healthy volunteers. The number of cytokine secreting cells decreased in never medicated patients after 3 months of lithium treatment. In vitro stimulation of PBLs with lithium did not affect the number of cytokine secreting cells either in the patients or in the healthy volunteers. CONCLUSIONS: The significantly lower number of PBLs producing cytokines (IL-2, IL-6, IL-10 and IFN-gamma) in euthymic BAD patients under chronic lithium treatment result from the long-term (over 3 months) lithium administration. In vitro stimulation of PBLs with lithium did not change the number of cytokine producing cells. Our findings may be useful in elucidating possible downregulatory effects of lithium in humans.

Adult↗

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.

Acetylcholine↗

Lithium-methomyl induced seizures in rats: a new model of status epilepticus?

Behavioral, electroencephalographic (EEG) and neuropathological effects of methomyl, a carbamate insecticide reversibly inhibiting acetylcholinesterase activity, were studied in naive or lithium chloride (24 h, 3 mEq/kg, s.c.) pretreated male Wistar rats. In naive animals, methomyl with equal potency produced motor limbic seizures and fatal status epilepticus. Thus, the CD50 values (50% convulsant dose) for these seizure endpoints were almost equal to the LD50 (50% lethal dose) of methomyl (13 mg/kg). Lithium pretreated rats were much more susceptible to convulsant, but not lethal effect of methomyl. CD50 values of methomyl for motor limbic seizures and status epilepticus were reduced by lithium pretreatment to 3.7 mg/kg (a 3.5-fold decrease) and 5.2 mg/kg (a 2.5-fold decrease), respectively. In contrast, lithium pretreatment resulted in only 1.3-fold decrease of LD50 value of methomyl (9.9 mg/kg). Moreover, lithium-methomyl treated animals developed a long-lasting status epilepticus, which was not associated with imminent lethality observed in methomyl-only treated rats. Scopolamine (10 mg/kg) or diazepam (10 mg/kg) protected all lithium-methomyl treated rats from convulsions and lethality. Cortical and hippocampal EEG recordings revealed typical epileptic discharges that were consistent with behavioral seizures observed in lithium-methomyl treated rats. In addition, convulsions induced by lithium-methomyl treatment were associated with widespread neurodegeneration of limbic structures. Our observations indicate that lithium pretreatment results in separation between convulsant and lethal effects of methomyl in rats. As such, seizures induced by lithium-methomyl administration may be an alternative to lithium-pilocarpine model of status epilepticus, which is associated with high lethality.

Animals↗

Lithium induces brain-derived neurotrophic factor and activates TrkB in rodent cortical neurons: an essential step for neuroprotection against glutamate excitotoxicity.

Mechanisms underlying the therapeutic effects of lithium for bipolar mood disorder remain poorly understood. Recent studies demonstrate that lithium has neuroprotective actions against a variety of insults in vitro and in vivo. This study was undertaken to investigate the role of the brain-derived neurotrophic factor (BDNF)/TrkB signaling pathway in mediating neuroprotection of lithium against glutamate excitotoxicity in cortical neurons. Pretreatment with either lithium or BDNF protected rat cerebral cortical neurons from glutamate excitotoxicity. The duration of treatment required to elicit maximal neuroprotection by BDNF (1 day) was much shorter than that by lithium (6 days). K252a, an inhibitor of Trk tyrosine kinases, and a BDNF neutralizing antibody suppressed the neuroprotective effect of lithium. Treatment of cortical neurons with lithium increased the cellular BDNF content in 3 days and the phosphorylation of TrkB at Tyr490 in 5 days, suggesting that long-term lithium administration enhances BDNF expression/secretion, leading to the activation of TrkB receptor. Lithium failed to protect against glutamate excitotoxicity in cortical neurons derived from homozygous and heterozygous BDNF knockout mice, although lithium fully protected cortical neurons prepared from wild type mice littermates. Taken together, these data suggest that the BDNF/TrkB pathway plays an essential role in mediating the neuroprotective effect of lithium.

Animals↗

Open-label study of the effect of combination quetiapine/lithium therapy on lithium pharmacokinetics and tolerability.

OBJECTIVE: The aim of this study was to assess the effect of oral quetiapine on the steady-state pharmacokinetics of lithium. METHODS: This was an open-label trial in patients with schizophrenia, schizoaffective disorder, or bipolar disorder who had demonstrated tolerability to combination lithium/ antipsychotic therapy. Patients received lithium for at least 1 week before screening and throughout the 18-day trial. Quetiapine was coadministered in fixed, stepwise, increasing doses of 25 to 250 mg TID on days 4 through 11, and maintained at 250 mg TID on days 12 through 14. Blood samples were drawn to monitor plasma concentrations of lithium and quetiapine. Psychiatric assessments included the Brief Psychiatric Rating Scale, the Clinical Global Impression severity of illness item, and the modified Scale for the Assessment of Negative Symptoms. Neurologic function was assessed using the Simpson-Angus Scale and the Abnormal Involuntary Movement Scale. Other assessments included clinical laboratory testing, electrocardiography, physical examinations, and monitoring for spontaneously reported adverse events. RESULTS: Nine men and 1 woman (mean [SE] age, 32.8 [1.9] years; mean [SE] body weight, 87.6 [3.3] kg) entered and completed the 18-day trial. Eight patients had bipolar disorder, 1 had paranoid schizophrenia, and 1 had schizoaffective disorder. Morning trough concentrations of lithium in serum (days 2, 6, 8, 10, 12, 14, and 17), as well as quetiapine and 2 of its metabolites in plasma (days 12, 13, and 14), did not appear to vary noticeably. Small increases were observed in the mean values of the area under the 12-hour serum lithium concentration-time curve and the maximum and minimum observed serum lithium concentrations when quetiapine was added to the lithium regimen. However, the increases were not considered clinically relevant by the investigators and were not statistically significant. A total of 91 adverse events were reported, 67 (73.6%) of which were not attributed to trial treatment. The most commonly reported adverse events during coadministration of lithium and quetiapine were somnolence (90.0% [9/10]), asthenia (70.0% [7/10]), dry mouth (30.0% [3/10]), nausea (30.0% [3/10]), vomiting (30.0% [3/10]), dizziness (30.0% [3/10]), tremor (30.0% [3/10]), and insomnia (20.0% [2/10]). There were no serious adverse events. CONCLUSIONS: Measures of lithium and quetiapine concentrations did not vary significantly during combination therapy. Coadministered lithium and quetiapine were well tolerated in the patients studied.

Adult↗

Factors associated with patients' knowledge of and attitudes towards treatment with lithium.

BACKGROUND: Treatment with lithium is often compromised by poor adherence, by side-effects and by patients' having serum levels outside the therapeutic range. These factors may be affected by patients' knowledge and attitudes towards lithium, and we set out to establish factors associated with knowledge about and attitudes towards lithium among a large representative sample of patients. METHOD: Patients known to be taking lithium in Grampian during 1995 were surveyed postally during 1998 with the Lithium Knowledge Test (LKT) and the Lithium Attitudes Questionnaire (LAQ). Scores on these measures were analysed against patients' sociodemographic and clinical characteristics by stepwise multiple regression. RESULTS: Of 742 patients, 411 (55%) completed an LKT and 362 (49%) completed an LAQ. Stepwise multiple regression established that positive attitudes towards lithium on the LAQ were associated with higher serum lithium levels (P=0.005) and with continuing to take lithium (P<0.001). Higher knowledge on the LKT was associated with positive attitudes on the LAQ (P=0.002), with younger age (P<0.001), and with shorter duration of treatment (P=0.01) LIMITATIONS: The study was retrospective and the response rate was relatively low. CONCLUSIONS: Education about lithium is likely to be of particular importance in the elderly and 'refresher courses' are advisable for those who have been on lithium for lengthy periods. Interventions which modify attitudes, rather than enhancing knowledge, are likely to be helpful in promoting adherence.

Adult↗

Lithium prophylaxis of recurrent bipolar affective disorder: long-term outcome and its psychosocial correlates.

BACKGROUND: Discrepancy between efficacy of prophylactic lithium and its effectiveness in ordinary clinical practice necessitates long-term follow-up data from specialised lithium clinics. Also, role of psychosocial factors in influencing the outcome is unclear. METHODS: One hundred and eighteen patients of bipolar affective disorder attending a lithium clinic were followed-up for approximately 11 years (range 2-27 years). Demographic and clinical data, measures of social support and psychosocial stress were obtained at the intake in 1989-1990. Study design combined retrospective chart-review (till the time of intake) with prospective follow-up till July 1995. RESULTS: On lithium, the patients had a mean of 0.43 relapses per year (manic, 0.26; depressive, 0.17) which was significantly less (p < 0.01) than the pre-lithium episode frequency. The figure for entirely relapse-free patients was 24%, and 62% had relapses up to one episode per year (median = 0.3 per year). Fifty-eight (49%) patients were good responders to lithium (relapses < or = 0.30 per year). In comparison to good responders, partial/poor responders had a significantly greater number of pre-lithium depressive episodes, poor lithium compliance, more psychosocial stress and lower social support at intake. These variables correlated well with relapses and explained 32% of the variance of the data. CONCLUSIONS: Lithium had a definite prophylactic effect on long-term outcome. Social support and stressful life events are significant correlates of response to lithium. CLINICAL IMPLICATIONS: Lithium prophylaxis of bipolar affective disorders seems justified though psychosocial factors appear to modulate its effectiveness. LIMITATIONS: Other psychotropic medications were used during relapse and the assessment of psychosocial factors was cross-sectional.

Adolescent↗

The mechanism of lithium action: state of the art, ten years later.

Lithium is an effective drug for both treatment and prophylaxis of bipolar disorder. However, the mechanism of lithium action is still unknown. The inositol depletion hypothesis is supported by biochemical and behavioral data in rats, but primate inositol levels are higher than in rodents and may obviate the effects of depletion. Inhibition of 5HT autoreceptors by lithium is supported by biochemical and behavioral data in rats but would seem more related to lithium's antidepressant than to its antimanic or prophylactic effects. Lithium induces increases in levels of the anti-apoptotic factor Bcl-2. This effect could be most relevant for treatment of neurodegenerative disorders. Lithium inhibits glycogen synthase kinase-3, which is involved in a wide range of signal transduction pathways. However, this lithium effect occurs at high concentrations and may be more relevant for its toxic effect. Lithium in low concentrations induces accumulation of PAP, which affects several cellular processes including RNA processing. However, PAP phosphatase is present more in peripheral tissues than in brain. This lithium effect could explain some of its peripheral side effects. Chronic lithium administration upregulates glutamate reuptake and thus decreases glutamate availability in synapse. Glutamate is an excitatory neurotransmitter and its reduction could exert an antimanic effect. Biochemical and clinical experiments are necessary to determine the key mechanism of lithium efficacy in treatment and prophylaxis of affective disorders.

5'-Nucleotidase↗

Endogenous versus exogenous lithium clearance for evaluation of dopamine-induced changes in renal tubular function.

1. The present randomized, double-blind cross-over study compared endogenous and exogenous lithium clearance (CLi) for estimation of the effect of dopamine on tubular sodium reabsorption. Twelve normal, salt-repleted male subjects were investigated on three different occasions with either placebo or 450 mg or 600 mg of lithium given in random order at 22.00 hours. After an overnight fast, renal clearance studies were performed during a 1 h baseline period and subsequently during the second hour of an infusion of 3 micrograms min-1 kg-1 of dopamine. 2. Baseline values of endogenous CLi and fractional excretion of lithium (FELi) [27.0 (23.5-30.5) ml/min and 24.2 (20.3-28.2)% (means with 95% confidence interval)] were lower than exogenous values [lithium, 450 mg: 32.7 (29.9-35.4) ml/min (P < 0.05) and 27.4 (25.2-29.6)% (P < 0.05); lithium, 600 mg: 33.4 (29.2-37.6)ml/min (P < 0.05) and 28.6 (26.3-31.0)% (P < 0.01)]. Both test doses of lithium increased the baseline sodium clearance (CNa), but glomerular filtration rate and urine flow rate remained unchanged. 3. Dopamine increased CNa to similar values on the three study days. CLi increased to 40.9 (35.5-46.5) ml/min (endogenous lithium, P < 0.001), 43.2 (40.8-45.6) ml/min (450 mg of lithium, P < 0.01) and 44.9 (41.3-48.4) ml/min (600 mg of lithium, P < 0.001), respectively. FELi increased to 32.2 (27.5-37.0)% (P < 0.01), 35.4 (33.0-37.7)% (P < 0.01) and 35.9 (32.8-38.9)% (P < 0.01), respectively. Values during dopamine infusion did not differ significantly. 4. The lower baseline values of endogenous CLi and FELi compared with exogenous values suggest that CLi in humans depends on the plasma concentrations of lithium. However, the effect of dopamine on CLi and FELi was expressed to the same extent with endogenous and exogenous lithium, indicating that the two methods are interchangeable for estimation of dopamine-induced changes in tubular function.

Adult↗

Systematic overview of lithium treatment in acute mania.

OBJECTIVE: To evaluate the efficacy of lithium in the treatment of acute mania. METHOD: Systematic overview of the literature and meta-analysis of randomised controlled trials. Estimation of (i) the differences in the reduction in mania severity scores, and (ii) the ratio and difference in improvement response rates. RESULTS: A total of 658 patients from 12 trials were included. Treatment periods ranged from 3 to 4 weeks. The response rate ratio for lithium against placebo was 1.95 (95%CI 1.17-3.23). The mean number needed to treat was five (95%CI 3-20). Patients were twice as likely to obtain remission with lithium than with chlorpromazine (rate ratio = 1.96, 95%CI 1.02-3.77). The mean number needed to treat was four (95%CI 3-9). Neither carbamazepine nor valproate was more effective than lithium. The response rate ratios were 1.01 (95%CI 0.54-1.88) for lithium compared to carbamazepine and 1.22 (95%CI 0.91-1.64) for lithium against valproate. Haloperidol was no better than lithium on the basis of improvement based on assessment of global severity. The differences in effects between lithium and risperidone were -2.79 (95%CI -4.22 to -1.36) in favour of risperidone with respect to symptom severity improvement and -0.76 (95%CI -1.11 to -0.41) on the basis of reduction in global severity of disease. Symptom and global severity was as well controlled with lithium as with verapamil. Lithium caused more side-effects than placebo and verapamil, but no more than carbamazepine or valproate. CONCLUSION: The clinical trial evidence suggests that lithium should remain the first line treatment for acute mania.

Acute Disease↗

Selective inhibition of the expression of signal transduction proteins by lithium in nerve growth factor-differentiated PC12 cells.

This investigation examined if lithium, the primary therapeutic treatment for bipolar affective disorder, modulated the levels of selected signal transduction proteins in PC12 cells. Nerve growth factor (NGF) induced differentiation of PC12 cells, and after 12 days of NGF treatment there were large increases in the levels of the heterotrimeric G protein subunits alpha o1, alpha i1, beta, and alpha s, small increases in those of alpha i2 and alpha q, and a slight decrease in that of alpha o2. Lithium (1 mM, equivalent to the therapeutic concentration) selectively reduced NGF-induced increases in levels of G protein subunits, generally having the greatest inhibition on those that were increased the most by NGF. Lithium at 5 mM had greater inhibitory effects than 1 mM lithium on NGF-induced increases in levels of G proteins, but neither concentration of lithium affected the induction of the cytoskeletal protein beta-tubulin. Examination of other proteins involved in signal transduction revealed that 12 days of NGF treatment increased the level of protein kinase C-alpha, but not those of the beta, epsilon, or zeta subtypes, and did not alter the levels of beta, gamma, or delta phospholipase C. Pretreatment with lithium inhibited the increase in content of protein kinase C-alpha induced by NGF but had little effect on the proteins not responsive to NGF except for decreasing the levels of protein kinase C-epsilon. The inhibitory effect of lithium was found not to be due to inhibition of NGF-induced tyrosine phosphorylation, which was unaffected by 5 mM lithium, or to inositol depletion. In summary, use of the dynamic system of NGF-induced PC12 cell differentiation provided a sensitive model in which to identify signal transduction proteins that were influenced by lithium treatment. The large changes caused by a therapeutically equivalent concentration of lithium lend support to the proposal that the selective inhibitory effects of lithium on subtypes of G proteins and protein kinase C may be important therapeutic targets.

Animals↗

[Lithium and its effects on the endocrine system, bones and peripheral nerves--a current review].

Controlled studies in 1990-1992 with Danish, Sardinian, and Hongkong-Chinese patients consistently revealed a prevalence of goiter of about 50% in lithium treated patients. This is far beyond the frequency generally assumed for Germany, the whole country still known to be an endemic goiter area. Hypothyroidism as a side effect of lithium occurs in a clearly different group of patients and is much less frequent, the overall incidence being not substantially different from the incidence in the general population. But the risk of becoming hypothyroid as well as hyperparathyroid during lithium prophylaxis is markedly higher in women over 45 years of age, who in the general population are also prone to both endocrine dysfunctions. Lithium is considered to have a provoking role. Lithium is known to be accumulated in the bone and an impact on bone metabolism was shown in animal studies. The data reviewed prohibit the use of lithium during lactation and enforce strict indication in children. In adults the effect of lithium on bone should be considered only in osteomalacia and severe osteoporosis. This review is illustrated by the case of a 60-year-old woman, who after 4 years of successful treatment with lithiumcarbonate because of schizoaffective psychosis, developed a syndrome of hypercalcemia. Exstirpation of a parathyroid adenoma rendered her normocalcemic. Moreover, a pre-existing diffuse goiter had grown to a large nodular goiter within the course of her 5-year treatment. As she finally became paraparetic, she was admitted to our rehabilitation center for the diseases of the spinal cord. Her paraparesis may have been caused not only by the lithium-induced primary HPT, but in part by lithium itself. There are a few reports on lithium causing peripheral neuropathy at toxic levels. A transient deterioration of a pre-existing neuropathy, as in our case study, may have happened at lithium serum levels not far beyond the upper limit of 0.8 mmol/l.

Adult↗

Postinsult treatment with lithium reduces brain damage and facilitates neurological recovery in a rat ischemia/reperfusion model.

Lithium has long been a primary drug used to treat bipolar mood disorder, even though the drug's therapeutic mechanisms remain obscure. Recent studies demonstrate that lithium has neuroprotective effects against glutamate-induced excitotoxicity in cultured neurons and in vivo. The present study was undertaken to examine whether postinsult treatment with lithium reduces brain damage induced by cerebral ischemia. We found that s.c. injection of lithium dose dependently (0.5-3 mEq/kg) reduced infarct volume in the rat model of middle cerebral artery occlusionreperfusion. Infarct volume was reduced at a therapeutic dose of 1 mEq/kg even when administered up to 3 h after the onset of ischemia. Neurological deficits induced by ischemia were also reduced by daily administration of lithium over 1 week. Moreover, lithium treatment decreased the number of neurons showing DNA damage in the ischemic brain. These neuroprotective effects were associated with an up-regulation of cytoprotective heat shock protein 70 (HSP70) in the ischemic brain hemisphere as determined by immunohistochemistry and Western blotting analysis. Lithium-induced HSP70 up-regulation in the ischemic hemisphere was preceded by an increase in the DNA binding activity of heat shock factor 1, which regulates the transcription of HSP70. Physical variables and cerebral blood flow were unchanged by lithium treatment. Our results suggest that postinsult lithium treatment reduces both ischemia-induced brain damage and associated neurological deficits. Moreover, the heat shock response is likely to be involved in lithium's neuroprotective actions. Additionally, our studies indicate that lithium may have clinical utility for the treatment of patients with acute stroke.

Animals↗

Lithium acutely inhibits and chronically up-regulates and stabilizes glutamate uptake by presynaptic nerve endings in mouse cerebral cortex.

We previously reported that lithium stimulated extracellular glutamate accumulation in monkey and mouse cerebrocortical slices. We report here that this is caused by lithium-induced inhibition of glutamate uptake into the slice. Glutamate release was amplified 5-fold over inhibition of uptake. When the effects of lithium and the specific glutamate transporter inhibitors, L-trans-pyrrolidine-2, 4-dicarboxylic acid and dihydrokainic acid, were plotted as glutamate accumulation vs. inhibition of glutamate uptake, the plots were superimposable. This finding strongly indicates that lithium-induced glutamate accumulation is caused entirely by inhibition of uptake. With cerebrocortical synaptosomes, inhibition of glutamate uptake was greater than in slices, suggesting that presynaptic nerve endings are the primary site of inhibition of uptake by lithium. Inhibition of uptake was caused by a progressive lowering of Vmax, as the lithium concentration was increased, whereas the Km remained constant, indicating that lithium inhibited the capacity of the transporter but not its affinity. Chronic treatment of mice with lithium, achieving a blood level of 0.7 mM, which is on the low side of therapeutic, up-regulated synaptosomal uptake of glutamate. This would be expected to exert an antimanic effect. Lithium is a mood stabilizer, dampening both the manic and depressive phases of bipolar disorder. Interestingly, although the uptake of glutamate varied widely in individual control mice, uptake in lithium-treated mice was stabilized over a narrow range (variance in controls, 0.423; in lithium treated, 0.184).

Animals↗