Symptomatic reactive hypoglycemia during glucose tolerance test in lithium-treated patients

New Advances in the Pharmacology and Toxicology of Lithium: A Neurobiologically Oriented Overview

Over the last six decades, lithium has been considered the gold standard treatment for the long-term management of bipolar disorder due to its efficacy in preventing both manic and depressive episodes as well as suicidal behaviors. Nevertheless, despite numerous observed effects on various cellular pathways and biologic systems, the precise mechanism through which lithium stabilizes mood remains elusive. Furthermore, there is recent support for the therapeutic potential of lithium in other brain diseases. This review offers a comprehensive examination of contemporary understanding and predominant theories concerning the diverse mechanisms underlying lithium's effects. These findings are based on investigations utilizing cellular and animal models of neurodegenerative and psychiatric disorders. Recent studies have provided additional support for the significance of glycogen synthase kinase-3 (GSK3) inhibition as a crucial mechanism. Furthermore, research has shed more light on the interconnections between GSK3-mediated neuroprotective, antioxidant, and neuroplasticity processes. Moreover, recent advancements in animal and human models have provided valuable insights into how lithium-induced modifications at the homeostatic synaptic plasticity level may play a pivotal role in its clinical effectiveness. We focused on findings from translational studies suggesting that lithium may interface with microRNA expression. Finally, we are exploring the repurposing potential of lithium beyond bipolar disorder. These recent findings on the therapeutic mechanisms of lithium have provided important clues toward developing predictive models of response to lithium treatment and identifying new biologic targets. SIGNIFICANCE STATEMENT: Lithium is the drug of choice for the treatment of bipolar disorder, but its mechanism of action in stabilizing mood remains elusive. This review presents the latest evidence on lithium's various mechanisms of action. Recent evidence has strengthened glycogen synthase kinase-3 (GSK3) inhibition, changes at the level of homeostatic synaptic plasticity, and regulation of microRNA expression as key mechanisms, providing an intriguing perspective that may help bridge the mechanistic gap between molecular functions and its clinical efficacy as a mood stabilizer.

Psychotropic Drug Effects on Steroid Stress Hormone Release and Possible Mechanisms Involved

There is no doubt that chronic stress accompanied by adrenocortical stress hormone release affects the development and treatment outcome of several mental disorders. Less attention has been paid to the effects of psychotropic drugs on adrenocortical steroids, particularly in clinical studies. This review focuses on the knowledge related to the possible modulation of cortisol and aldosterone secretion under non-stress and stress conditions by antipsychotic drugs, which are being used in the treatment of several psychotic and affective disorders. The molecular mechanisms by which antipsychotic drugs may influence steroid stress hormones include the modulation of central and/or adrenocortical dopamine and serotonin receptors, modulation of inflammatory cytokines, influence on regulatory mechanisms in the central part of the hypothalamic-pituitary axis, inhibition of corticotropin-releasing hormone gene promoters, influencing glucocorticoid receptor-mediated gene transcription, indirect effects via prolactin release, alteration of signaling pathways of glucocorticoid and mineralocorticoid actions. Clinical studies performed in healthy subjects, patients with psychosis, and patients with bipolar disorder suggest that single and repeated antipsychotic treatments either reduce cortisol concentrations or do not affect its secretion. A single and potentially long-term treatment with dopamine receptor antagonists, including antipsychotics, has a stimulatory action on aldosterone release.

Maternal lithium use and the risk of adverse pregnancy and neonatal outcomes: a Swedish population-based cohort study

BACKGROUND

Lithium is prescribed during pregnancy, but there is limited information about pregnancy and neonatal outcomes following in utero exposure. Thus, this study aimed to investigate the associations between lithium use and adverse pregnancy and neonatal outcomes.

METHODS

This population-based cohort study examined associations between maternal lithium use and major adverse pregnancy and neonatal outcomes via inverse probability weighted propensity score regression models.

RESULTS

Of 854,017 women included in this study, 434 (0.05%) used lithium during pregnancy. Among pre-specified primary outcomes, lithium use during pregnancy was associated with an increased risk of spontaneous preterm birth (8.7% vs 3.0%; adjusted relative risk [aRR] 2.64 95% CI 1.82, 3.82) and birth of a large for gestational age infant (9.0% vs 3.5%; aRR 2.64 95% CI 1.91, 3.66), but not preeclampsia nor birth of a small for gestational age infant. Among secondary outcomes, lithium use was associated with an increased risk of cardiac malformations (2.1% vs 0.8%; aRR 3.17 95% CI 1.64, 6.13). In an analysis restricted to pregnant women with a diagnosed psychiatric illness (n=9552), associations remained between lithium and spontaneous preterm birth, birth of a large for gestational age infant, and cardiovascular malformations; and a positive association with neonatal hypoglycaemia was also found. These associations were also apparent in a further analysis comparing women who continued lithium treatment during pregnancy to those who discontinued prior to pregnancy.

CONCLUSIONS

Lithium use during pregnancy is associated with an increased risk of spontaneous preterm birth and other adverse neonatal outcomes. These potential risks must be balanced against the important benefit of treatment and should be used to guide shared decision-making.

Clinical response and metabolic effects of lithium in 323 mood disorder patients

BACKGROUND

Lithium is the mainstay for the maintenance treatment of mood disorders (MD), but its efficacy needs to be weighed against its side effects profile. Here, we assessed retrospectively the clinical response to long-term lithium treatment, as well as the rate of associated metabolic side effects.

METHODS

Clinical data were collected from patients treated with lithium for at least 12 months at the Lucio Bini Center for Mood Disorders in Cagliari, Italy. Clinical response was determined as the difference in number of mood episodes and percent of illness time before and during lithium treatment. Symptomatic values of metabolic parameters (plasma levels of glucose, cholesterol, urea nitrogen [BUN], creatinine, TSH, white blood cells [WBC]), and Body Mass Index (BMI) were determined.

RESULTS

We studied 323 MD patients (60.2% women). The percent of illness time was significantly reduced for both depressive (F = 4.94, p<0.0001), and manic (F = 3.95, p < 0.0001) episodes, whereas the rates of episodes/year were significantly reduced for mania (F = 2.01, p = 0.02), but not for depression (F = 1.54, p = 0.06). Rates of MD patients with symptomatic values of metabolic parameters were 14.3% for WBC ≥10,000/µl, 26.9% for glucose levels ≥100 mg/dl, 54.2% for cholesterol levels ≥200 mg/dl, 7.5% for BUN ≥50 mg/dl, 21.9% for creatinine levels ≥1.2 mg/dl, and 20.9% for TSH levels ≥3.50 mU/l.

CONCLUSIONS

Long-term lithium treatment was clinically effective, but the rates of metabolic effects were substantial although some of them were also associated with older age. Lithium-treated patients should receive accurate clinical monitoring to decrease the impact of long-term side effects.

Drug-Induced Endocrine and Metabolic Disorders

Complex interactions exist amongst the various components of the neuroendocrine system in order to maintain homeostasis, energy balance and reproductive function. These components include the hypothalamus-pituitary- adrenal and -gonadal axes, the renin-angiotensin-aldosterone system, the sympathetic nervous system and the pancreatic islets. These hormones, peptides and neurotransmitters act in concert to regulate the functions of many organs, notably the liver, muscles, kidneys, thyroid, bone, adrenal glands, adipocytes, vasculature, intestinal tract and gonads, through many intermediary pathways. Endocrine and metabolic disorders can arise from imbalance amongst numerous hormonal factors. These disturbances may be due to endogenous processes, such as increased secretion of hormones from a tumour, as well as exogenous drug administration. Drugs can cause endocrine abnormalities via different mechanisms, including direct alteration of hormone production, changes in the regulation of the hormonal axis, effects on hormonal transport, binding, and signalling, as well as similar changes to counter-regulatory hormone systems. Furthermore, drugs can affect the evaluation of endocrine parameters by causing interference with diagnostic tests. Common drug-induced endocrine and metabolic disorders include disorders of carbohydrate metabolism, electrolyte and calcium abnormalities, as well as drug-induced thyroid and gonadal disorders. An understanding of the proposed mechanisms of these drug effects and their evaluation and differential diagnosis may allow for more critical interpretation of the clinical observations associated with such disorders, better prediction of drug-induced adverse effects and better choices of and rationales for treatment.

Lithium's effects on rat liver glucose metabolism in vivo

Oral administration of lithium carbonate to fed-healthy rats strongly decreased liver glycogen content, despite the simultaneous activation of glycogen synthase and the inactivation of glycogen phosphorylase. The effect seemed to be related to a decrease in glucose 6-phosphate concentration and to a decrease in glucokinase activity. Moreover, in these animals lithium markedly decreased liver fructose 2,6-bisphosphate, which could be a consequence of the fall in glucose 6-phosphate and of the inactivation of 6-phosphofructo-2-kinase. Liver pyruvate kinase activity and blood insulin also decreased after lithium administration. Lower doses of lithium carbonate had less intense effects. Lithium administration to starved-healthy and fed-streptozotocin-diabetic rats caused a slight increase in blood insulin, which was simultaneous with increases in liver glycogen, glucose 6-phosphate, and fructose 2, 6-phosphate. Glucokinase, 6-phosphofructo-2-kinase, and pyruvate kinase activities also increased after lithium administration in starved-healthy and fed-diabetic rats. Lithium treatment activated glycogen synthase and inactivated glycogen phosphorylase in a manner similar to that observed in fed-healthy rats. Glycemia was not modified in any group of animals. These results indicate that lithium acts on liver glycogen metabolism in vivo in at least two different ways: one related to changes in insulinemia, and the other related to the direct action of lithium on the activity of some key enzymes of liver glucose metabolism.

A role for phospholipase C activity in GLUT4-mediated glucose transport

Overexpression of surrogate receptors [epidermal growth factor (EGF) receptor (EGFR) and platelet-derived growth factor receptor] in adipocytes has demonstrated that multiple signaling pathways may lead to GLUT4-mediated glucose uptake. These implicated pathways function independently of IRS-1 phosphorylation and PI3-kinase activation. In addition, we previously demonstrated that EGFR tyrosyl autophosphorylation is required to stimulate GLUT4-mediated glucose transport in 3T3-L1 adipocytes. This observation suggests that signaling molecules that are dependent on EGFR autophosphorylation, such as phospholipase C (PLC), may lie in the signaling pathway to glucose transport. As PLC has been implicated in glucose transport by several clinical and basic mechanistic studies, we investigated whether EGFR signaling may promote glucose transport via modulation of PLC activity. Activation of EGFR overexpressing 3T3-L1 adipocytes leads to a 3.4 +/- 1.2-fold stimulation of PLC activity over basal levels vs. only 1.06 +/- 0.01-fold stimulation by insulin. Pharmacological inhibition of PLC by 50 microM U73122 reduced phosphoinositide accumulation by 79.2 +/- 16.9% and resulted in a concomitant 56.0 +/- 12.7% decrease in EGF-induced glucose transport. This inhibition of glucose transport by U73122 was specific, because the inactive congener, U73343, failed to block EGF-induced glucose transport. Despite the low levels of insulin-induced PLC activity, insulin-stimulated glucose transport activity was similarly inhibited by U73122 (55.9 +/- 13.1% inhibition). Inhibition of PLC activation did not impair either EGF- or insulin-induced activation of glycogen synthase or incorporation of glucose into lipid, supporting the hypothesis that both EGF- and insulin-induced glucose disposal can be independent of GLUT4-mediated glucose transport. The diminution of glucose transport secondary to inhibition of PLC activity was reflected by a decrease in GLUT4 translocation to the plasma membrane upon either EGF or insulin stimulation. These results are consistent with either a permissive or an active role for PLC activity in the translocation of GLUT4 to the plasma membrane.

Effect of lithium on plasma glucose, insulin and glucagon in normal and streptozotocin-diabetic rats: role of glucagon in the hyperglycaemic response

1. Lithium salts, used in the treatment of affective disorders, may have adverse effects on glucose tolerance in man, and suppress glucose-stimulated insulin secretion in rats. 2. To study the interaction of these effects with pre-existing diabetes mellitus, plasma glucose and insulin responses to lithium chloride were measured in male Wistar rats made diabetic with intraperitoneal streptozotocin, and in normal controls. 3. In both normal and diabetic anaesthetized rats, intravenous lithium (4 mEq kg-1) caused a rise in plasma glucose. In absolute terms, the rise was greater in diabetic (5.2 mmol l-1) than in normal rats (2.3 mmol l-1). 4. Plasma insulin concentrations were reduced by lithium in normal rats, but the low insulin concentrations measured in the diabetic rats were not significantly changed. 5. After intravenous glucose (0.5 g kg-1), lithium-treated diabetic rats showed a second rise in plasma glucose at 60-90 min without any insulin response, while normal rats showed typically reduced insulin responses and initial glucose disappearance rates. 6. Intravenous glucose reduced plasma glucagon concentrations to a greater extent in normal than in diabetic rats, but lithium induced an equal rise in plasma glucagon in both groups, with a time-course similar to that of the hyperglycaemic effect. 7. The hyperglycaemic action of lithium is greater in the hypoinsulinaemic diabetic rats and appears to involve a stimulation of glucagon secretion in both normal and diabetic animals.