Induction of hyperglycemia in mice with atypical antipsychotic drugs that inhibit glucose uptake

Interaction of amisulpride with GLUT1 at the blood-brain barrier. Relevance to Alzheimer's disease

Blood-brain barrier (BBB) dysfunction may be involved in the increased sensitivity of Alzheimer's disease (AD) patients to antipsychotics, including amisulpride. Studies indicate that antipsychotics interact with facilitated glucose transporters (GLUT), including GLUT1, and that GLUT1 BBB expression decreases in AD. We tested the hypotheses that amisulpride (charge: +1) interacts with GLUT1, and that BBB transport of amisulpride is compromised in AD. GLUT1 substrates, GLUT1 inhibitors and GLUT-interacting antipsychotics were identified by literature review and their physicochemical characteristics summarised. Interactions between amisulpride and GLUT1 were studied using in silico approaches and the human cerebral endothelial cell line, hCMEC/D3. Brain distribution of [3H]amisulpride was determined using in situ perfusion in wild type (WT) and 5xFamilial AD (5xFAD) mice. With transmission electron microscopy (TEM) we investigated brain capillary degeneration in WT mice, 5xFAD mice and human samples. Western blots determined BBB transporter expression in mouse and human. Literature review revealed that, although D-glucose has no charge, charged molecules can interact with GLUT1. GLUT1 substrates are smaller (184.95±6.45g/mol) than inhibitors (325.50±14.40g/mol) and GLUT-interacting antipsychotics (369.38±16.04). Molecular docking showed beta-D-glucose (free energy binding: -15.39kcal/mol) and amisulpride (-29.04kcal/mol) interact with GLUT1. Amisulpride did not affect [14C]D-glucose hCMEC/D3 accumulation. [3H]amisulpride uptake into the brain (except supernatant) of 5xFAD mice compared to WT remained unchanged. TEM revealed brain capillary degeneration in human AD. There was no difference in GLUT1 or P-glycoprotein BBB expression between WT and 5xFAD mice. In contrast, caudate P-glycoprotein, but not GLUT1, expression was decreased in human AD capillaries versus controls. This study provides new details about the BBB transport of amisulpride, evidence that amisulpride interacts with GLUT1 and that BBB transporter expression is altered in AD. This suggests that antipsychotics could potentially exacerbate the cerebral hypometabolism in AD. Further research into the mechanism of amisulpride transport by GLUT1 is important for improving antipsychotics safety.

Presynaptic 5-HT2A-mGlu2/3 Receptor–Receptor Crosstalk in the Prefrontal Cortex: Metamodulation of Glutamate Exocytosis

The glutamatergic nerve endings of a rat prefrontal cortex (PFc) possess presynaptic 5-HT_2A heteroreceptors and mGlu2/3 autoreceptors, whose activation inhibits glutamate exocytosis, and is measured as 15 mM KCl-evoked [³H]D-aspartate ([³H]D-asp) release (which mimics glutamate exocytosis). The concomitant activation of the two receptors nulls their inhibitory activities, whereas blockade of the 5-HT_2A heteroreceptors with MDL11,939 (1 μM) strengthens the inhibitory effect elicited by the mGlu2/3 receptor agonist LY329268 (1 μM). 5-HT_2A receptor antagonists (MDL11,939; ketanserin; trazodone) amplify the impact of low (3 nM) LY379268. Clozapine (0.1–10 μM) mimics the 5-HT_2A agonist (±) DOI and inhibits the KCl-evoked [³H]D-asp overflow in a MDL11,939-dependent fashion, but does not modify the (±) DOI-induced effect. mGlu2 and 5-HT_2A proteins do not co-immunoprecipitate from synaptosomal lysates, nor does the incubation of PFc synaptosomes with MDL11,939 (1 μM) or clozapine (10 µM) modify the insertion of mGlu2 subunits in synaptosomal plasma membranes. In conclusion, 5-HT_2A and mGlu2/3 receptors colocalize, but do not physically associate, in PFc glutamatergic terminals, where they functionally interact in an antagonist-like fashion to control glutamate exocytosis. The mGlu2/3-5-HT_2A metamodulation could be relevant to therapy for central neuropsychiatric disorders, including schizophrenia, but also unveil cellular events accounting for their development, which also influence the responsiveness to drugs regimens.

An inhibitory and beneficial effect of chlorpromazine and promethazine (C + P) on hyperglycolysis through HIF-1α regulation in ischemic stroke

BACKGROUND

After ischemic stroke, the increased catabolism of glucose (hyperglycolysis) results in the production of reactive oxygen species (ROS) via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). A depressive or hibernation-like effect of C + P on brain activity was reported to induce neuroprotection. The current study assesses the effect of C + P on hyperglycolysis and NOX activation.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion. At the onset of reperfusion, rats received C + P with or without temperature control, or phloretin [glucose transporter (GLUT)-1 inhibitor], or cytochalasin B (GLUT-3 inhibitor). We detected brain ROS, apoptotic cell death, and ATP levels along with HIF-1α expression. Cerebral hyperglycolysis was measured by glucose, protein expression of GLUT-1/3, and phosphofructokinase-1 (PFK-1), as well as lactate and lactate dehydrogenase (LDH) at 6 and 24 h of reperfusion. The enzymatic activity of NOX and protein expression of its subunits (gp91^phox) were detected. Neural SHSY5Y cells were placed under 2 h of oxygen-glucose deprivation (OGD) followed by reoxygenation for 6 and 24 h with C + P treatment. Cell viability and protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91^phox were measured. A HIF-1α overexpression vector was transfected into the cells, and then protein levels of HIF-1α, GLUT-1/3, PFK-1, and LDH were quantitated. In sham-operated rats and control cells, the protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91^phox were measured at 6 and 24 h after C + P administration.

RESULTS

C + P reduced the protein elevations after stroke in HIF-1α, glycolytic enzymes, as well as in ROS, cell death, glucose and lactate, but raised ATP levels in the brain. In ischemic rats exposed to GLUT-1/3 inhibitors, ROS, cell death, glucose, and lactate were all decreased, as well as GLUT-1, GLUT-3, LDH, and PFK-1 protein levels. C + P decreased ischemia-induced NOX activation by reducing the enzymatic activity and protein expression of the NOX subunit gp91^phox, as was observed in the presence of GLUT-1/3 inhibitors. These markers were significantly decreased following C + P administration with the induced hypothermia, while C + P administration with temperature control at 37 °C induced lesser protection after ischemia stroke. In the OGD/reoxygenation model, C + P treatment increased cell viability and diminished protein levels of HIF-1α, GLUT-1, GLUT-3, PFK-1, LDH, and gp91^phox. However, in OGD with HIF-1α overexpression, C + P was unable to effectively reduce the upregulated GLUT-1, GLUT-3, and LDH. In normal conditions, C + P reduced HIF-1α and the levels of key glycolytic enzymes depending on its pharmacological effect.

CONCLUSION

C + P, partially depending on hypothermia, attenuates hyperglycolysis and NOX activation through HIF-1α regulation.

Drugs Affecting Body Weight, Body Fat Distribution, and Metabolic Function-Mechanisms and Possible Therapeutic or Preventive Measures: an Update

PURPOSE OF REVIEW

Weight gain and body fat redistribution are common side effects of many widely used drugs. We summarize recent literature on prevalence data and mechanisms associated with drug-induced body fat changes and mechanisms to prevent or treat metabolic side effects.

RECENT FINDINGS

The highest prevalence of metabolic complications is seen with antipsychotics and antiretroviral drugs used in the treatment of HIV and may, at least partly, be responsible for the increased risk for co-morbid diseases such as diabetes, steatosis of the liver, and cardiovascular disease. The pathogenetic mechanisms leading to weight gain from antipsychotics are increasingly known and help to unravel the complex interaction that exists between psychopathology and metabolic complications. Although the classic lipodystrophy mainly occurred with older HIV drugs, also with the newer HIV treatment, weight gain seems to be a major side effect. Early detection of the metabolic consequences of drugs can lead to an early diagnosis of the complications and their treatment. Different medications, including the newer antidiabetics, are being studied in the therapy of drug-induced obesity. Future research should focus on identifying individuals at risk for metabolic side effects and on early markers to identify individuals with side effects so that timely treatment of metabolic complications can be initiated.

Do proinflammatory cytokines play a role in clozapine-associated glycometabolism disorders?

RATIONALE AND OBJECTIVE

Clozapine (CLZ) is the most effective drug for treatment-resistant schizophrenia but is associated with many side effects, including glycometabolism disorders. Immunological mechanisms may be involved in the development of clozapine side effects. Research relating the immunomodulatory effects of clozapine and its early markers to clinically relevant adverse events is needed to reduce the harmful side effects of clozapine. This study aimed to investigate the role of proinflammatory cytokines in clozapine-associated glycometabolism disorders.

METHODS

We measured the effect of a range of doses of clozapine on glycometabolism-related parameters and proinflammatory cytokines levels in mice peripheral blood. We also examined the differences between these indicators in the peripheral blood of clozapine-treated schizophrenia patients and healthy controls. Furthermore, we detected proinflammatory cytokines expression in mice pancreatic tissue.

RESULTS

Following clozapine administration, glucagon significantly decreased in mouse serum, and proinflammatory cytokine IL-β levels markedly increased. Clozapine reliably increased proinflammatory cytokines (IL-1β, IL-6, and TNF-α) expression in murine pancreatic tissue. Compared with healthy controls, clozapine-treated patients' BMI, blood glucose, and proinflammatory cytokines (IL-1β, IL-6, and TNF-α) increased significantly. In clozapine-treated patients, a higher clozapine daily dosage was associated with higher levels of the proinflammatory cytokines IL-1β and IL-6, and a significant positive correlation was observed between blood glucose levels and the proinflammatory cytokines IL-6 and TNF-α.

CONCLUSION

Findings from animal experiments and clinical trials have shown clear evidence that clozapine has a regulatory effect on immune-related proinflammatory cytokines and influences glycometabolism indicators.

Sex-dependent alterations of dopamine receptor and glucose transporter density in rat hypothalamus under long-term clozapine and haloperidol medication

OBJECTIVE

Sex-dependent disturbances of peripheral glucose metabolism are known complications of antipsychotic drug treatment. The influence of long-term clozapine and haloperidol medication on hypothalamus, maintaining aspects of internal body homeostasis, has not yet been completely clarified.

METHODS

After puberty, male and female Sprague Dawley rats were fed orally with ground pellets containing haloperidol (1 mg/kgBW/day) or clozapine (20 mg/kgBW/day) for 12 weeks. The hypothalamic protein expression of dopamine receptors D2R and D4R, melanocortin receptor MC4R, and glucose transporters Glut1 and Glut3 was examined. Glucose, glycogen, lactate, and pyruvate levels were determined, also malondialdehyde equivalents as markers of oxidative stress.

RESULTS

D2R expression was increased in the male haloperidol and clozapine group but decreased in females medicated with clozapine. D4R expression was upregulated under clozapine medication. While females showed increased Glut1, Glut3 was elevated in both male and female clozapine-medicated animals. We found no changes of hypothalamic malondialdehyde, glycogen, and MC4R. Hypothalamic lactate was elevated in the female clozapine group.

CONCLUSION

Clozapine sex-dependently affects the expression of D2R, Glut1, and Glut3. The upregulation of the glucose transporters indicates glucose deprivation in the endothelial cells and consequently in astrocytes and neurons. Increased hypothalamic lactate in females under clozapine points to enhanced glycolysis with a higher glucose demand to produce the required energy. Haloperidol did not change the expression of the glucose transporters and upregulated D2R only in males.

Impact of Chronic Risperidone Use on Behavior and Survival of 3xTg-AD Mice Model of Alzheimer's Disease and Mice With Normal Aging

Psychosis and/or aggression are common problems in dementia, and when severe or persistent, cause considerable patient distress and disability, caregiver stress, and early institutionalization. In 2005, the Food and Drug Administration (FDA) determined that atypical antipsychotics were associated with a significantly greater mortality risk compared to placebo, which prompted the addition of an FDA black-box warning. The American College of Neuropsychopharmacology (ACNP) White Paper, 2008, reviewed this issue and made clinical and research recommendations regarding the use of antipsychotics in dementia patients with psychosis and/or agitation. Increased mortality risk has also been described in cerebrovascular adverse events in elderly users of antipsychotics. In the present work, at the translational level, we used male 3xTg-AD mice (PS1M146V, APPSwe, tauP301L) at advanced stages of the disease reported to have worse survival than females, to study the behavioral effects of a low chronic dose of risperidone (0.1 mg/kg, s.c., 90 days, from 13 to 16 months of age) and its impact on long-term survival, as compared to mice with normal aging. Animals were behaviorally assessed for cognitive and BPSD (behavioral and psychological symptoms of dementia)-like symptoms in naturalistic and experimental conditions (open-field test, T-maze, social interaction, Morris water maze, and marble test) before and after treatment. Weight, basal glucose levels, and IPGTT (i.p. glucose tolerance test) were also recorded. Neophobia in the corner test was used for behavioral monitoring. Survival curves were recorded throughout the experiment until natural death. The benefits of risperidone were limited, both at cognitive and BPSD-like level, and mostly restricted to burying, agitation/vibrating tail, and other social behaviors. However, the work warns about a clear early mortality risk window during the treatment and long-lasting impact on survival. Reduced life expectancy and life span were observed in the 3xTg-AD mice, but total lifespan (36 months) recorded in C57BL/6 × 129Sv counterparts with normal aging was also truncated to 28 months in those with treatment. Sarcopenia at time of death was found in all groups, but was more severe in wild-type animals treated with risperidone. Therefore, the 3xTg-AD mice and their non-transgenic counterparts can be useful to delimitate critical time windows and for studying the physio-pathogenic factors and underlying causal events involved in this topic of considerable public health significance.

Second-generation antipsychotics and metabolism alterations: a systematic review of the role of the gut microbiome

RATIONALE

Multiple drugs are known to induce metabolic malfunctions, among them second-generation antipsychotics (SGAs). The pathogenesis of such adverse effects is of multifactorial origin.

OBJECTIVES

We investigated whether SGAs drive dysbiosis, assessed whether gut microbiota alterations affect body weight and metabolic outcomes, and looked for the possible mechanism of metabolic disturbances secondary to SGA treatment in animal and human studies.

METHODS

A systematic literature search (PubMed/Medline/Embase/ClinicalTrials.gov/PsychInfo) was conducted from database inception until 03 July 2018 for studies that reported the microbiome and weight alterations in SGA-treated subjects.

RESULTS

Seven articles reporting studies in mice (experiments = 8) and rats (experiments = 3) were included. Olanzapine was used in five and risperidone in six experiments. Only three articles (experiments = 4) in humans fit our criteria of using risperidone and mixed SGAs. The results confirmed microbiome alterations directly (rodent experiments = 5, human experiments = 4) or indirectly (rodent experiments = 4) with predominantly increased Firmicutes abundance relative to Bacteroidetes, as well as weight gain in rodents (experiments = 8) and humans (experiments = 4). Additionally, olanzapine administration was found to induce both metabolic alterations (adiposity, lipogenesis, plasma free fatty acid, and acetate levels increase) (experiments = 3) and inflammation (experiments = 2) in rodents, whereas risperidone suppressed the resting metabolic rate in rodents (experiments = 5) and elevated fasting blood glucose, triglycerides, LDL, hs-CRP, antioxidant superoxide dismutase, and HOMA-IR in humans (experiment = 1). One rodent study suggested a gender-dependent effect of dysbiosis on body weight.

CONCLUSIONS

Antipsychotic treatment-related microbiome alterations potentially result in body weight gain and metabolic disturbances. Inflammation and resting metabolic rate suppression seem to play crucial roles in the development of metabolic disorders.

Atypical antipsychotics-induced metabolic syndrome and nonalcoholic fatty liver disease: a critical review

The atypical antipsychotics (AAPs) have been used as first-line drugs in psychiatric practice for a wide range of psychotic disorders, including schizophrenia and bipolar mania. While effectively exerting therapeutic effects on positive and negative symptoms, as well as cognitive impairments in schizophrenia patients, these drugs are less likely to induce extrapyramidal symptoms compared to typical antipsychotics. However, the increasing application of them has raised questions on their tolerability and adverse effects over the endocrine, metabolic, and cardiovascular axes. Specifically, AAPs are associated to different extents, with weight gain, metabolic syndrome (MetS), and nonalcoholic fatty liver disease (NAFLD). This article summarized clinical evidence showing the metabolic side effects of AAPs in patients with schizophrenia, and experimental evidence of AAPs-induced metabolic side effects observed in animals and cell culture studies. In addition, it discussed potential mechanisms involved in the APPs-induced MetS and NAFLD.

Current Views on Dopaminergic Drugs Affecting Glucose Homeostasis

BACKGROUND

For more than three decades, it has been known that manipulation of dopaminergic system could affect glucose homesotasis in experimental animals. The notion that glucose homeostasis in human might be influenced by dopaminergic drugs has attracted a great deal of attention in the past two decades. In spite of rapid advancements in revealing involvement of dopaminergic neurotransmission in insulin release, glucose up-take and pancreatic beta cell function in general through centrally and peripherally controlled mechanisms, there are discrepancies among observations on experimental animals and human subjects.

CONCLUSION

With the expansion of pharmacotherapy in psychotic conditions, depression and endocrine abnormalities along with a sharp increase in prevalence of type two diabetes and disturbances of glucose homeostasis as a major risk factor for many cardiovascular complications and associated mortalities; it seems a critical analysis of recent investigations on drugs which act as agonists or antagonists of dopaminergic receptors in various tissues and organs may provide better insight into how safe and efficient these medicines could be prescribed. Furthermore, the other main objective of present review is to compare clinical data on significance of changes in blood glucose and insulin levels during short term and after long term treatment with these agents. This in turn would be beneficial for determining adequate strategies to combat or to avoid adverse effects associated with dopaminergic drug therapy.

Drug-induced obesity and its metabolic consequences: a review with a focus on mechanisms and possible therapeutic options

Weight gain is a common side effect of many widely used drugs. Weight gain of a few kilograms to an increase of 10% or more of initial body weight has been described. Not only the weight gain as such puts a burden on the health risks of the involved patients, the accompanying increase in the incidence of the metabolic syndrome, type 2 diabetes mellitus, and cardiovascular risk factors urges the caregiver to identify and to closely monitor the patients at risk. In this review, the different classes of drugs with significant weight gaining properties and the metabolic consequences are described. Specific attention is given to pathogenetic mechanisms underlying the metabolic effects and to potential therapeutic measures to prevent them.

Antenatal antipsychotic exposure induces multigenerational and gender-specific programming of adiposity and glucose tolerance in adult mouse offspring

Second-generation antipsychotics (SGAs) are well known for their metabolic side effects in humans, including obesity and diabetes. These compounds are maintained during pregnancy to prevent the relapse of psychoses, but they readily diffuse across the placenta to the fetus, as documented with the widely-prescribed drug olanzapine (OLZ). However, observational studies have provided conflicting results on the potential impact of SGAs on fetal growth and body weight, and their effects on metabolic regulation in the offspring. For this reason, our study has tested whether antenatal exposure of CD1 mice to OLZ influenced metabolic outcomes in the offspring of the first (F1) and second (F2) generations. In F1 mice, OLZ antenatal treatment caused a decrease in neonatal body weight in both genders, an effect that persisted throughout life only in male animals. Interestingly, F1 female mice also displayed altered glucose homoeostasis. F2 mice, generated by mating normal males with F1 female mice exposed to OLZ during antenatal life, exhibited higher neonatal body weights which persisted only in F2 female animals. This was associated with expansion of fat mass and a concordant pattern of adipose tissue gene expression. Moreover, male and female F2 mice were glucose-intolerant. Thus, our study has demonstrated that antenatal OLZ exposure induces multigenerational and gender-specific programming of glucose tolerance in the offspring mice as adults, and points to the need for careful monitoring of children exposed to SGAs during pregnancy.

Effect of a dosing-time on quetiapine-induced acute hyperglycemia in mice

Although rare, second-generation antipsychotic drugs cause severe hyperglycemia within several days after the initiation of therapy. Because glucose tolerance exhibits circadian rhythmicity, we evaluated an effect of a dosing-time on quetiapine-induced acute hyperglycemia in mice. A single intraperitoneal dose of quetiapine dosing-time-independently induced insulin resistance in fasted C57BL/6J mice. However, acute hyperglycemic effect was detected only after dosing of the drug at the beginning of an active phase. Under the conditions in which hepatic glucose production was stimulated by pyruvate administration, hyperglycemic effect of quetiapine was dosing-time-independently observed. In addition, the dosing-time-dependent hyperglycemic effect of quetiapine disappeared in the liver-specific circadian clock-disrupted mice in which circadian rhythmicity in hepatic glucose production is deranged. Furthermore, the dosing-time had little impact on the pharmacokinetics of quetiapine in normal mice. These results suggest that quetiapine acutely causes hyperglycemia only when hepatic glucose production elevates. Therefore, quetiapine therapy with once daily dosing at a rest phase might be safer than that at an active phase. Further studies are needed to confirm the hypothesis.

Pancreatic Islet Responses to Metabolic Trauma

Carbohydrate, lipid, and protein metabolism are largely controlled by the interplay of various hormones, which includes those secreted by the pancreatic islets of Langerhans. While typically representing only 1% to 2% of the total pancreatic mass, the islets have a remarkable ability to adapt to disparate situations demanding a change in hormone release, such as peripheral insulin resistance. There are many different routes to the onset of insulin resistance, including obesity, lipodystrophy, glucocorticoid excess, and the chronic usage of atypical antipsychotic drugs. All of these situations are coupled to an increase in pancreatic islet size, often with a corresponding increase in insulin production. These adaptive responses within the islets are ultimately intended to maintain glycemic control and to promote macronutrient homeostasis during times of stress. Herein, we review the consequences of specific metabolic trauma that lead to insulin resistance and the corresponding adaptive alterations within the pancreatic islets.

Diabetic ketoacidosis and severe hypertriglyceridaemia as a consequence of an atypical antipsychotic agent

The atypical antipsychotic agent clozapine, although an effective treatment for schizophrenia, is linked with metabolic adverse effects. We report a case of diabetic ketoacidosis and very severe hypertriglyceridaemia associated with clozapine use, in a patient with type 2 diabetes mellitus, who was successfully treated with continuous insulin infusion and fluids. As clozapine proved to be the most efficacious in controlling the patient's psychotic symptoms, the patient has been continued on clozapine despite its known metabolic side effects. Importantly the patient has achieved satisfactory long-term lipid and glycaemic control. The current recommendations related to the metabolic care for patients treated with atypical antipsychotic agents as well as the mechanisms behind abnormal glucose and lipid regulation with clozapine therapy are discussed.

Olanzapine Is Faster than Haloperidol in Inducing Metabolic Abnormalities in Schizophrenic and Bipolar Patients

The effects of olanzapine and haloperidol on metabolic parameters in bipolar patients have been evaluated much less comprehensively than in schizophrenic patients. Therefore, in this study, medical records of 343 schizophrenic and bipolar patients treated with haloperidol or olanzapine for 1 year were retrospectively reviewed and metabolic outcomes were evaluated. After 12 months of follow-up, 25.9% of patients showed ≥3 metabolic abnormalities with a point prevalence of 27.2% in the bipolar and 24.9% in the schizophrenic group: 22.0% of the schizophrenic patients treated with haloperidol and 29.8% of those treated with olanzapine achieved ≥3 metabolic alterations; in bipolar patients, these percentages were 15.8% of those treated with haloperidol and 37.8% of those treated with olanzapine (p < 0.0001). Significant changes were reported over time in fasting glucose, triglycerides and cholesterol blood levels, systolic and diastolic blood pressure, body weight, and BMI. Overall, a significant number of schizophrenic and bipolar patients treated with olanzapine showed ≥3 metabolic alterations in the first month of treatment when compared to those treated with haloperidol. Moreover, the number of olanzapine-treated patients developing metabolic changes in the first month was significantly higher in both diagnostic groups when compared to those who reached metabolic abnormal values in the subsequent 11 months. These data suggest that both antipsychotics could increase the metabolic risk in schizophrenic and bipolar patients with a higher prevalence in olanzapine-treated patients. On the other hand, olanzapine-treated patients seem to achieve metabolic abnormalities faster than haloperidol-treated subjects in both diagnostic groups.

Pathophysiological mechanisms of increased cardiometabolic risk in people with schizophrenia and other severe mental illnesses

Patients with schizophrenia have increased mortality and morbidity compared with the general population. These patients have a 20-year shorter lifespan than peers without schizophrenia, mainly due to premature cardiovascular disease, suicide, and cancer. Patients with severe mental illness are at increased risk for cardiovascular disease related to increased incidence of diabetes, hypertension, smoking, poor diet, obesity, dyslipidaemia, metabolic syndrome, low physical activity, and side-effects of antipsychotic drugs. Some second-generation antipsychotics (eg, clozapine, olanzapine, quetiapine, and risperidone) are associated with an increased risk of weight gain and obesity, impaired glucose tolerance and new-onset diabetes, hyperlipidaemia, and cardiovascular disease. The mechanisms by which schizophrenia and patients with severe mental illness are susceptible to cardiometabolic disorders are complex and include lifestyle risks and direct and indirect effects of antipsychotic drugs. An understanding of these risks might lead to effective interventions for prevention and treatment of cardiometabolic disorders in schizophrenia and severe mental illness.

Antipsychotics-induced metabolic alterations: focus on adipose tissue and molecular mechanisms

The use of antipsychotic drugs for the treatment of mood disorders and psychosis has increased dramatically over the last decade. Despite its consumption being associated with beneficial neuropsychiatric effects in patients, atypical antipsychotics (which are the most frequently prescribed antipsychotics) use is accompanied by some secondary adverse metabolic effects such as weight gain, dyslipidemia and glucose intolerance. The molecular mechanisms underlying these adverse effects are not fully understood but have been suggested to involve a dysregulation of adipose tissue homeostasis. As such, the aim of this paper is to review and discuss the role of adipose tissue in the development of secondary adverse metabolic effects induced by atypical antipsychotics. Data analyzed in this article suggest that atypical antipsychotics may increase adipose tissue (particularly visceral adipose tissue) lipogenesis, differentiation/hyperplasia, pro-inflammatory mediator secretion and insulin resistance and decrease adipose tissue lipolysis. Consequently, patients receiving antipsychotic medication could be at risk of developing obesity, type 2 diabetes and cardiovascular disease. A better knowledge of the impact of these drugs on adipose tissue homeostasis may unveil strategies to develop novel antipsychotic drugs with less adverse metabolic effects and to develop adjuvant therapies (e.g. behavioral and nutritional therapies) to neuropsychiatric patients receiving antipsychotic medication.

Clozapine acts as an agonist at serotonin 2A receptors to counter MK-801-induced behaviors through a βarrestin2-independent activation of Akt

The G protein-coupled serotonin 2A receptor (5-HT2AR) is a prominent target for atypical antipsychotic drugs, such as clozapine. Although clozapine is known to inhibit 5-HT2AR signaling through G protein-dependent mechanisms, it differs from classic GPCR antagonists, in that it also induces 5-HT2AR internalization and activates Akt signaling via a 5-HT2AR-mediated event. In this regard, clozapine may also be considered a functionally selective agonist. The cognate neurotransmitter at the 5-HT2AR, serotonin, also induces 5-HT2AR internalization and Akt phosphorylation. Serotonin promotes interactions with the scaffolding and regulatory protein, βarrestin2, which results in the recruitment and activation of Akt. These interactions prove to be critical for serotonin-induced, 5-HT2AR-mediated behavioral responses in mice. Herein, we sought to determine whether clozapine also utilizes βarrestin2-mediated mechanisms to induce 5-HT2AR signaling, and whether this interaction contributes to its behavioral effects in mice. We demonstrate that unlike serotonin, clozapine-mediated 5-HT2AR internalization and Akt phosphorylation is independent of receptor interactions with βarrestin2. Moreover, clozapine-mediated suppression of MK-801 and phencyclidine (PCP)-induced hyperlocomotion is βarrestin2 independent, although it is dependent upon Akt. These results demonstrate that pharmacologically oppositional ligands, serotonin and clozapine, utilize differential mechanisms to achieve the same 5-HT2AR-meadiated downstream events: Akt phosphorylation and receptor internalization. Although βarrestin2 has no effect on clozapine's actions in vivo, Akt phosphorylation is required for clozapine's efficacy in blocking MK-801- and PCP-induced models of schizophrenic behaviors in mice.

Metabolic issues in schizophrenic patients receiving antipsychotic treatment

Schizophrenia is a psychotic disorder with a complex pathophysiology and requires treatment that includes long term administration of antipsychotics that is said to be associated with metabolic syndrome. This study was designed to evaluate the impact of seven different antipsychotics prescribed to schizophrenic patients, on development of metabolic syndrome in the patients. A total of 210 patients with schizophrenia (30 patients in each drug therapy group) were recruited according to ICD-10 criteria and were assigned to receive the drug for 16 weeks. Measurement of anthropometric (body weight, waist circumference, blood pressure) and biochemical parameters (glucose, insulin, HOMA-IR, triglycerides, LDL, HDL) was done and the patients were subjected to ATP-III defined criteria for metabolic syndrome. Patients undergoing treatment with olanzapine were more prone to metabolic syndrome as the drug induces weight gain after 16 weeks of treatment. It also induces dyslipidemia (P < 0.001) and hyperglycemia (P < 0.01). Clozapine was found to be second most potent drug in inducing metabolic syndrome as the weight in clozapine treated patients increased after 16 weeks, along with a significant increase in glycemic (P < 0.001) and lipid parameters (P < 0.01). Aripriazole and amisulphride are comparatively safer drugs as their role in inducing metabolic abnormalities in schizophrenic patients was insignificant, although the impact of long term administration of these drugs needs to be explored. It is clear from the study that antipsychotic treatment induces metabolic syndrome so, it becomes important that the metabolic and cardiovascular risk factors should be surveillance regularly in schizophrenic patients undergoing antipsychotic treatment.

Second-generation antipsychotics cause a rapid switch to fat oxidation that is required for survival in C57BL/6J mice

Some second-generation antipsychotics (SGAs) increase insulin resistance and fat oxidation, but counter intuitively they do not activate lipolysis. This seems unsustainable for meeting energy demands. Here, we measured dose-dependent effects of SGAs on rates of oxygen consumption (VO2), respiratory exchange ratio (RER), and physical activity in C57BL/6J mice. The role of H1-histamine receptors and consequences of blocking fat oxidation were also examined. Olanzapine, risperidone, and clozapine (2.5-10mg/kg) elicited rapid drops in dark-cycle RER (~0.7) within minutes, whereas aripiprazole exerted only modest changes. Higher doses of olanzapine decreased VO2, and this was associated with accumulation of glucose in plasma. Clozapine and risperidone also lowered VO2, in contrast to aripiprazole, whereas all decreased physical activity. Astemizole and terfenadine had no significant effects on RER, VO2, or physical activity. The VO2 and RER effects appear independent of sedation/physical activity or H1-receptors. CPT-1 inhibitors can enhance muscle glucose utilization and prevent fat oxidation. However, after etomoxir (2 × 30 mg/kg), a low dose of olanzapine that did not significantly affect VO2 by itself caused precipitous drops in VO2 and body temperature, leading to death within hours or a moribund state requiring euthanasia. One 30 mg/kg dose of either etomoxir or 2-tetradecylglycidate followed by olanzapine, risperidone, or clozapine, but not aripiprazole, dramatically lowered VO2 and body temperature. Thus, mice treated with some SGAs shift their fuel utilization to mostly fat but are unable to either switch back to glucose or meet their energy demands when either higher doses are used or when fat oxidation is blocked.

An acute rat in vivo screening model to predict compounds that alter blood glucose and/or insulin regulation

INTRODUCTION

Drug-induced glucose dysregulation and insulin resistance have been associated with weight gain and potential induction and/or exacerbation of diabetes mellitus in the clinic suggesting they may be safety biomarkers when developing antipsychotics. Glucose and insulin have also been suggested as potential efficacy biomarkers for some oncology compounds. The objective of this study was to qualify a medium throughput rat in vivo acute Intravenous Glucose Tolerance Test (IVGTT) for predicting compounds that will induce altered blood glucose and/or insulin levels.

METHODS

Acute and sub-chronic studies were performed to qualify an acute IVGTT model. Double cannulated male rats (Han-Wistar and Sprague-Dawley) were administered vehicle, olanzapine, aripiprazole or other compounds at t=-44min for acute studies and at time=-44min on the last day of dosing for sub-chronic studies, treated with dextrose (time=0min; i.v.) and blood collected using an automated Culex® system for glucose and insulin analysis (time=-45, -1, 2, 10, 15, 30, 45, 60, 75, 90, 120, 150 and 180min).

RESULTS

Olanzapine significantly increased glucose and insulin area under the curve (AUC) values while aripiprazole AUC values were similar to control, in both acute and sub-chronic studies. All atypical antipsychotics evaluated were consistent with literature references of clinical weight gain. As efficacy biomarkers, insulin AUC but not glucose AUC values were increased with a compound known to have insulin growth factor-1 (IGF-1) activity, compared to control treatment.

DISCUSSION

These studies qualified the medium throughput acute IVGTT model to more quickly screen compounds for 1) safety - the potential to elicit glucose dysregulation and/or insulin resistance and 2) efficacy - as a surrogate for compounds affecting the glucose and/or insulin regulatory pathways. These data demonstrate that the same in vivo rat model and assays can be used to predict both clinical safety and efficacy of compounds.

Do atypical antipsychotics really enhance smoking reduction more than typical ones?: the effects of antipsychotics on smoking reduction in patients with schizophrenia

Whether atypical antipsychotics (AAs) can enhance smoking reduction in schizophrenic patients remains controversial because of methodological limitations in existing studies. This study explored whether certain types of antipsychotics predict smoking reduction in schizophrenic patients. Three hundred eight smoking, predominantly male schizophrenic patients (271/308 [88.9%]) participated in an 8-week open-label study with antismoking medications (high-dose, low-dose nicotine transdermal patch and bupropion). Antipsychotics were classified into (1) typical antipsychotics (TAs) and (2) AAs, including multiacting receptor-targeted antipsychotics (clozapine, olanzapine, and quetiapine), serotonin-dopamine antagonists (risperidone), D2/D3 receptor antagonists (amisulpride), and partial dopamine receptor agonists (aripiprazole). A general linear model was used to explore whether types of antipsychotic predict changes in the number of cigarettes smoked per day (CPD) and the score of the Fagerstrom Test for Nicotine Dependence (FTND) while controlling for confounding factors. The type of antipsychotic (TAs or AAs) was not significantly associated with smoking cessation (n = 21; χ = 1.8; df = 4; P = 0.77). Regarding smoking reduction, the type of antipsychotic was significantly predictive of a change in the CPD (P = 0.027; partial eta square = 0.055) and FTND scores (P = 0.002; partial eta square = 0.073). The 95% confidence intervals of the estimated means of change in the CPD and FTND scores did not contain zero only among subjects on TAs or clozapine.These findings suggest that TAs and clozapine enhance smoking reduction compared with nonclozapine atypical antipsychotics in schizophrenic patients. The mechanisms underlying the effects of various antipsychotics on smoking reduction remain unclear and warrant future study.

Preclinical pharmacokinetic and toxicological evaluation of MIF-1 peptidomimetic, PAOPA: examining the pharmacology of a selective dopamine D2 receptor allosteric modulator for the treatment of schizophrenia

Schizophrenia is a mental illness characterized by a breakdown in cognition and emotion. Over the years, drug treatment for this disorder has mainly been compromised of orthosteric ligands that antagonize the active site of the dopamine D2 receptor. However, these drugs are limited in their use and often lead to the development of adverse movement and metabolic side effects. Allosteric modulators are an emerging class of therapeutics with significant advantages over orthosteric ligands, including an improved therapeutic and safety profile. This study investigates our newly developed allosteric modulator, PAOPA, which is a specific modulator of the dopamine D2 receptor. Previous studies have shown PAOPA to attenuate schizophrenia-like behavioral abnormalities in preclinical models. To advance this newly developed allosteric drug from the preclinical to clinical stage, this study examines the pharmacokinetic behavior and toxicological profile of PAOPA. Results from this study prove the effectiveness of PAOPA in reaching the implicated regions of the brain for therapeutic action, particularly the striatum. Pharmacokinetic parameters of PAOPA were found to be comparable to current market antipsychotic drugs. Necropsy and histopathological analyses showed no abnormalities in all examined organs. Acute and chronic treatment of PAOPA indicated no movement abnormalities commonly found with the use of current typical antipsychotic drugs. Moreover, acute and chronic PAOPA treatment revealed no hematological or metabolic abnormalities classically found with the use of atypical antipsychotic drugs. Findings from this study demonstrate a better safety profile of PAOPA, and necessitates the progression of this newly developed therapeutic for the treatment of schizophrenia.

Potential role of prolactin in antipsychotic-mediated association of schizophrenia and type 2 diabetes

It remains unclear why atypical antipsychotics confer a risk for hyperglycemia compared to typical antipsychotics. Atypical antipsychotics antagonize dopamine receptors-2 (D(2)) and serotonin (5-HT) receptors-2, while typical antipsychotics antagonize only D(2) receptors. We aimed at elucidating the mechanistic differences between the role of typical and atypical antipsychotics on prolactin levels and glucose regulation. A Medline search was conducted during 2010 using the search terms type 2 diabetes (T2D), typical/atypical antipsychotics, schizophrenia, prolactin, and serotonin. We discuss the effect of typical and atypical antipsychotics on prolactin levels and glucose regulation. Given that prolactin is under negative control by dopamine and positive control by serotonin, typical antipsychotics induce elevations in prolactin, while atypical antipsychotics do not. Research studies show protective effects of prolactin on T2D. We hypothesize that the difference in induction of T2D between typical and atypical antipsychotics is due to the antipsychotic receptor binding mediated effect in changes in prolactin levels.

The HSP co-inducer BGP-15 can prevent the metabolic side effects of the atypical antipsychotics

Weight gain and dysfunction of glucose and lipid metabolism are well-known side effects of atypical antipsychotic drugs (AAPD). Here, we address the question whether a heat-shock protein (HSP) co-inducer, insulin sensitizer drug candidate, BGP-15, can prevent AAPD-induced glucose, lipid, and weight changes. We also examined how an AAPD alters HSP expression and whether BGP-15 alters that expression. Four different experiments are reported on the AAPD BGP-15 interventions in a human trial of healthy men, a rodent animal model, and an in vitro adipocyte cell culture system. Olanzapine caused rapid insulin resistance in healthy volunteers and was associated with decreased level of HSP72 in peripheral mononuclear blood cells. Both changes were restored by the administration of BGP-15. In Wistar rats, weight gain and insulin resistance induced by clozapine were abolished by BGP-15. In 3T3L1 adipocytes, clozapine increased intracellular fat accumulation, and BGP-15 inhibited this process. Taken together, our results indicate that BGP-15 inhibits multiple metabolic side effects of atypical antipsychotics, and this effect is likely to be related to its HSP co-inducing ability.

A novel insulin sensitizer drug candidate-BGP-15-can prevent metabolic side effects of atypical antipsychotics

Atypical antipsychotic drugs (AAPD) are widely used to treat severe psychiatric disorders, have well documented metabolic side effects such as disturbances in glucose metabolism, insulin resistance and weight gain. It has been shown that BGP-15, a hydroxylamine derivative with insulin sensitizing activity can prevent AAPD provoked fat accumulation in adipocyte cultures, and insulin resistance in animal experiments and in healthy volunteers. The aim of this study was to compare the preventive effect of BGP-15 with conventional oral antidiabetics on metabolic side effects of AAPDs. We found that BGP-15 that does not belong to either conventional insulin sensitizers or oral antidiabetics, is able to counteract insulin resistance and weight gain provoked by antipsychotic agents in rats while rosiglitazone and metformin were not effective in the applied doses. Our results confirm that BGP-15 is a promising new drug candidate to control the metabolic side effects of atypical antipsychotics. Data indicate that this rat model is suitable to analyze the metabolic side effects of AAPDs and the protective mechanism of BGP-15.

After six months of anti-psychotic treatment: Is the improvement in mental health at the expense of physical health?

INTRODUCTION

The morbidity and mortality due to cardiovascular causes in patients with schizophrenia is higher than in the general population, a fact that has been observed more since second generation anti-psychotics came into general use.

OBJECTIVES

To determine the incidence of metabolic syndrome in patients with a previously untreated first psychotic episode, as well as the prospective changes in the parameters that define the criteria of metabolic syndrome.

METHOD

An observational study with a prospective cohort design including patients who were admitted to the Acute Unit of Donostia Hospital.

RESULTS

A total of 21 patients were included in the study, of which 19 completed it. Just over one-quarter (26.3%) of the patients developed a metabolic syndrome at six months. Statistically significant differences were observed in the following parameters: 1) abdominal perimeter measurement with an increase of 14.6 cm at six months (P=.001); 2) triglyceride levels with a mean increase over the initial measurement of 48.99 mg/dl (P=.039); and 3) fasting blood glucose levels with a mean increase of 10.72 mg/dl (P=.001).

CONCLUSIONS

Significant changes were observed in metabolic parameters in a short period with the subsequent risk of associated cardiovascular events in a group of young patients. Actions are required directed at ensuring appropriate monitoring of these patients in order to measures to minimise the risks.

Atypical antipsychotics and the neural regulation of food intake and peripheral metabolism

The atypical antipsychotics (AAPs) are associated with weight gain and an increased incidence of metabolic disease including type 2 diabetes mellitus. Epidemiological, cross-sectional and prospective studies suggest that two of the AAPs, olanzapine and clozapine, cause the most dramatic weight gain and metabolic impairments including increased fasting glucose, insulin and triglycerides. Relative to the other AAPs, both olanzapine and clozapine exhibit a particularly high antagonistic affinity for histamine and muscarinic receptors which have been hypothesized as mediators of the reported increase in weight and glucose abnormalities. In this article, we review the current evidence for the AAP associated weight gain and abnormal glucose metabolism. We postulate that the effects of the AAPs on food intake and peripheral metabolism are initially independently regulated but with increasing body adiposity, the early AAP-induced impairments in peripheral metabolism will be exacerbated, thereby establishing a vicious cycle such that the effects of the AAP are magnified by the known pathophysiological consequences of obesity. Furthermore, we examine how inhibition of the histaminergic pathway may mediate increases in food intake and the potential role of the vagus nerve in the reported peripheral metabolic effects.

Clozapine and lithium require Caenorhabditis elegans β-arrestin and serum- and glucocorticoid-inducible kinase to affect Daf-16 (FOXO) localization

Numerous studies have implicated low levels of signaling in the Akt network with psychotic illnesses, and a growing body of literature has shown that all classes of antipsychotic drugs increase Akt signaling. The most clinically effective antipsychotic drug is clozapine. With Caenorhabditis elegans as a model system, this study demonstrates that clozapine is unique among antipsychotic drugs because it requires β-arrestin and serum and glucocorticoid-inducible kinase (SGK) in addition to Akt to suppress the nuclear localization of DAF-16 (Forkhead box O [FOXO]). Lithium, a mood stabilizer often used to treat psychosis, also requires β-arrestin and SGK to suppress the nuclear localization of DAF-16.

Does the association with diabetes say more about schizophrenia and its treatment?--the GLUT hypothesis

All effective anti psychotic drugs block glucose transporter proteins (GLUTs), peripherally and in the brain. These drugs are implicated in hyperglycaemia as demonstrated in mouse and human studies. Clozapine is the strongest blocker, with Haloperidol the weakest. The GLUT hypothesis suggests that schizophrenia is partly due to poor functioning of brain glucose transporters (GLUT 1 and 3). Neuronal glucose malnutrition could result in excessive neuronal pruning (so called Crow's Type 2 with a predominance of negative symptoms) or result in recurrent/ineffective pruning (Type 1 with positive symptoms). GLUT blockade by anti psychotic agents could assist Type 1 patients to complete the pruning process by deactivating already damaged neurones and circuits, but will make Type 2 patients more cognitively impaired. Future treatment options are discussed in line with the above formulation.

Alstonine as an antipsychotic: effects on brain amines and metabolic changes

Managing schizophrenia has never been a trivial matter. Furthermore, while classical antipsychotics induce extrapyramidal side effects and hyperprolactinaemia, atypical antipsychotics lead to diabetes, hyperlipidaemia, and weight gain. Moreover, even with newer drugs, a sizable proportion of patients do not show significant improvement. Alstonine is an indole alkaloid identified as the major component of a plant-based remedy used in Nigeria to treat the mentally ill. Alstonine presents a clear antipsychotic profile in rodents, apparently with differential effects in distinct dopaminergic pathways. The aim of this study was to complement the antipsychotic profile of alstonine, verifying its effects on brain amines in mouse frontal cortex and striatum. Additionally, we examined if alstonine induces some hormonal and metabolic changes common to antipsychotics. HPLC data reveal that alstonine increases serotonergic transmission and increases intraneuronal dopamine catabolism. In relation to possible side effects, preliminary data suggest that alstonine does not affect prolactin levels, does not induce gains in body weight, but prevents the expected fasting-induced decrease in glucose levels. Overall, this study reinforces the proposal that alstonine is a potential innovative antipsychotic, and that a comprehensive understanding of its neurochemical basis may open new avenues to developing newer antipsychotic medications.

Central nervous system delivery of the antipsychotic olanzapine induces hepatic insulin resistance

OBJECTIVE

Olanzapine (OLZ) is an atypical antipsychotic whose clinical efficacy is hampered by side effects including weight gain and diabetes. Recent evidence shows that OLZ alters insulin sensitivity independent of changes in body weight and composition. The present study addresses whether OLZ-induced insulin resistance is driven by its central actions.

RESEARCH DESIGN AND METHODS

Sprague-Dawley rats received an intravenous (OLZ-IV group) or intracerebroventricular (OLZ-ICV group) infusion of OLZ or vehicle. Glucose kinetics were assessed before (basal period) and during euglycemic-hyperinsulinemic clamp studies.

RESULTS

OLZ-IV caused a transient increase in glycemia and a higher rate of glucose appearance (R(a)) in the basal period. During the hyperinsulinemic clamp, the glucose infusion rate (GIR) required to maintain euglycemia and the rate of glucose utilization (R(d)) were decreased in OLZ-IV, whereas endogenous glucose production (EGP) rate was increased compared with vehicle-IV. Consistent with an elevation in EGP, the OLZ-IV group had higher hepatic mRNA levels for the enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase. Phosphorylation of hypothalamic AMP-activated protein kinase (AMPK) was increased in OLZ-IV rats compared with controls. Similarly, an intracerebroventricular infusion of OLZ resulted in a transient increase in glycemia as well as a higher R(a) in the basal period. During the hyperinsulinemic period, OLZ-ICV caused a decreased GIR, an increased EGP, but no change in R(d). Furthermore, OLZ-ICV rats had increased hepatic gluconeogenic enzymes and elevated hypothalamic neuropeptide-Y and agouti-related protein mRNA levels.

CONCLUSIONS

Acute central nervous system exposure to OLZ induces hypothalamic AMPK and hepatic insulin resistance, pointing to a hypothalamic site of action for the metabolic dysregulation of atypical antipsychotics.

A murine model of atypical antipsychotic-induced weight gain and metabolic dysregulation

In comparison with conventional, first-generation antipsychotics (e.g., haloperidol), the administration of atypical antipsychotics (AAPs) has been associated with a higher risk of metabolic derangements, including body weight increase, dysregulation of glucose homeostasis, fat accumulation, and even liability to develop type II diabetes. Since this is a serious clinical problem that may be further exacerbated in overweight schizophrenics, establishing animal models of AAP-induced adverse effects may contribute to clarifying the mechanisms underlying these effects. Here we present three basic protocols by which this problem has been modeled. The three protocols differ in many aspects (routes of administration, extent of the chronic treatment, diets, and dosage regimen), and the pros and cons of each procedure are systematically detailed throughout. It should be noted that several factors (e.g., species, sex, duration, and class of AAPs) could restrict the feasibility of these models, as well as their correspondence to the clinical condition.

The time-dependent change of insulin secretion in schizophrenic patients treated with olanzapine

The second generation antipsychotic drugs (SGAs) are effective in treating patients with schizophrenia and have been considered as the first line therapy. Recently, increasing attention has been drawn to the potential diabetogenic effect of these novel antipsychotics. The goal of this study was to evaluate the time-dependent effects of olanzapine treatment on pancreatic beta cell function in SGA-naïve schizophrenic patients. Forty-two schizophrenic subjects received olanzapine therapy for 8 weeks and thirty-three of them completed the trial. Of whom 33 completers (21 male, mean+/-SD age: 37.6+/-8.0 years) were inpatients and unexposed to SGA. The metabolic parameters were quantitatively assessed at weeks 0, 2, 4, and 8 by the intravenous glucose tolerance test. After 56-day olanzapine treatment, subjects had significant increases in body weight and as well as in the levels of triglyceride, total cholesterol, and low-density lipoprotein. Insulin secretion significantly decreased at week 2, returned to baseline at week 4, and significantly increased at week 8. Of the total samples, 18.2% and 33.3% of them met the criteria for significant weight gain and metabolic syndrome after 8-week olanzapine treatment, respectively. This study indicates that olanzapine-treated schizophrenic patients displayed biphasic changes in insulin secretion to a hyperglycemic challenge. The results of this study support that olanzapine might directly influence pancreatic beta cell function.

Delineating biological pathways unique to embryonic stem cell-derived insulin-producing cell lines from their noninsulin-producing progenitor cell lines

To identify unique biochemical pathways in embryonic stem cell-derived insulin-producing cells as potential therapeutic targets to prevent or delay beta-cell dysfunction or death in diabetic patients, comparative genome-wide gene expression studies of recently derived mouse insulin-producing cell lines and their progenitor cell lines were performed using microarray technology. Differentially expressed genes were functionally clustered to identify important biochemical pathways in these insulin-producing cell lines. Biochemical or cellular assays were then performed to assess the relevance of these pathways to the biology of these cells. A total of 185 genes were highly expressed in the insulin-producing cell lines, and computational analysis predicted the pentose phosphate pathway (PPP), clathrin-mediated endocytosis, and the peroxisome proliferator-activated receptor (PPAR) signaling pathway as important pathways in these cell lines. Insulin-producing ERoSHK cells were more resistant to hydrogen peroxide (H(2)O(2))-induced oxidative stress. Inhibition of PPP by dehydroepiandrosterone and 6-aminonicotinamide abrogated this H(2)O(2) resistance with a concomitant decrease in PPP activity as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Clathrin-mediated endocytosis, which is essential in maintaining membrane homeostasis in secreting cells, was up-regulated by glucose in ERoSHK but not in their progenitor ERoSH cells. Its inhibition by chlorpromazine at high glucose concentration was toxic to the cells. Troglitazone, a PPARG agonist, up-regulated expression of Ins1 and Ins2 but not Glut2. Gene expression analysis has identified the PPP, clathrin-mediated endocytosis, and the PPAR signaling pathway as the major delineating pathways in these insulin-producing cell lines, and their biological relevance was confirmed by biochemical and cellular assays.

Neurobehavioral deficits in db/db diabetic mice

Recent clinical studies indicate neurobehavioral disturbances in type-2 diabetics. However, there is paucity of preclinical research to support this concept. The validity of db/db mouse as an animal model to study type-2 diabetes and related complications is known. The present study was designed to investigate comprehensively the db/db mouse behavior as preclinical evidence of type-2 diabetes related major neurobehavioral complications. We tested juvenile (5-6weeks) and adult (10-11weeks) db/db mice for behavioral depression in forced swim test (FST), psychosis-like symptoms using pre-pulse inhibition (PPI) test, anxiety behavior employing elevated plus maze (EPM) test, locomotor behavior and thigmotaxis using open field test and working memory deficits in Y-maze test. Both juvenile and adult group db/db mice displayed behavioral despair with increased immobility time in FST. There was an age-dependent progression of psychosis-like symptoms with disrupted PPI in adult db/db mice. In the EPM test, db/db mice were less anxious as observed by increased percent open arms time and entries. They were also hypo-locomotive as evident by a decrease in their basic and fine movements. There was no impairment of working memory in the Y-maze test in db/db mice. This is the first report of depression, psychosis-like symptoms and anxiolytic behavior of db/db mouse strain. It is tempting to speculate that this mouse strain can serve as useful preclinical model to study type-2 diabetes related neurobehavioral complications.

Differential effects of various typical and atypical antipsychotics on plasma glucose and insulin levels in the mouse: evidence for the involvement of sympathetic regulation

Atypical antipsychotic treatment has been associated with serious metabolic adverse events, such as glucose dysregulation and development of type 2 diabetes. As part of our studies on possible underlying mechanisms, we investigated the acute effects of various typical and atypical antipsychotics on plasma glucose and insulin in FVB/N mice, a strain that showed a more pronounced hyperglycemic response to clozapine than C57BL/6 and CD-1 mice. Acute administration of high doses of clozapine, olanzapine, quetiapine, perphenazine, or chlorpromazine significantly increased plasma glucose by 100%-140% above basal levels without significant effects on insulin levels. In contrast, risperidone reduced plasma glucose (-30%) and markedly enhanced plasma insulin levels. Doses of ziprasidone that gave 50-fold higher free plasma concentrations than therapeutic plasma levels, as well as high doses of aripiprazole and haloperidol, did not significantly alter either glucose or insulin levels. Clozapine- and olanzapine-induced hyperglycemia occurred at free plasma concentrations that were within, or one order of magnitude above, the range of therapeutic plasma levels. Pretreatment with either the ganglionic blocker hexamethonium, or the alpha(2) adrenergic receptor antagonist yohimbine, blocked the clozapine- and chlorpromazine-induced increase in glucose levels. Taken together, these results suggest that typical and atypical antipsychotics with known metabolic liability produce acute hyperglycemia in mice and that this effect is likely driven by activation of the sympathetic autonomic nervous system via a central mechanism.

Protection from olanzapine-induced metabolic toxicity in mice by acetaminophen and tetrahydroindenoindole

OBJECTIVE

In mice and in humans, treatment with the second-generation antipsychotic drug olanzapine (OLZ) produces excessive weight gain, adiposity and secondary metabolic complications, including loss of glucose and insulin homeostasis. In mice consuming a high-fat (HF) diet, a similar phenotype develops, which is inhibited by the analgesic acetaminophen (APAP) and by the antioxidant tetrahydroindenoindole (THII). Therefore, we examined the ability of APAP and THII to prevent metabolic changes in mice receiving OLZ.

DESIGN AND MEASUREMENT

C57BL/6J mice received either a normal diet or a HF diet, and were administered daily dosages of OLZ (3 mg kg(-1) body weight), alone or with APAP (30 mg kg(-1) body weight) or THII (4.5 mg kg(-1) body weight), for 10 weeks. Parameters of body composition and metabolism, including glucose and insulin homeostasis and oxidative stress, were examined.

RESULTS

OLZ treatment doubled the HF diet-induced increases in body weight and percent body fat. These increases were partially prevented by both APAP and THII, although food consumption was constant in all groups. The THII protection was associated with an increase in whole body and mitochondrial respiration. OLZ also exacerbated, and both APAP and THII prevented, HF diet-induced loss of glucose tolerance and insulin resistance. As increased body fat promotes insulin resistance by a pathway involving oxidative stress, we evaluated production of reactive oxygen and lipid peroxidation in white adipose tissue (WAT). HF diet caused an increase in lipid peroxidation, NADPH-dependent O(2) uptake and H(2)O(2) production, which were further exacerbated by OLZ. APAP, THII and the NADPH oxidase inhibitor, diphenyleneiodonium chloride, each abolished oxidative stress in WAT.

CONCLUSIONS

We conclude that both APAP and THII intervene in the development of obesity and metabolic complications associated with OLZ treatment.

30 days of continuous olanzapine infusion determines energy imbalance, glucose intolerance, insulin resistance, and dyslipidemia in mice

The aim of this study was to model in mice the association between metabolic syndrome and the administration of atypical antipsychotic (AAP). Two dosages (4 and 8 mg/kg per day) of olanzapine (OL) were infused in 36 female mice for 30 days by osmotic mini-pumps. This study was also designed to further extend the implications raised in other experiments by our model of AAP-induced metabolic dysregulation. Through the use of the osmotic mini-pumps, this model is aimed to circumvent the shorter (than in humans) half-life of AAPs in rodents and to chronically administer OL by a reliable and less disturbing method. Indirect calorimetry was used to evaluate metabolic rate (MR) and respiratory exchange ratio together with weight and caloric intake. Serum insulin, leptin, and glucose tolerance (oral glucose tolerance test) were assessed. Pancreatic beta cells insulin levels, periuterine and liver fat content were also analyzed. Olanzapine-infused mice exhibited a reduction of overall MR (kilojoule per hour) and resting MR and respiratory exchange ratio, with periuterine fat significantly enlarged. All metabolic alterations were detected at the highest dose, with major effects found on weight gain and hyperphagia. Impaired glucose metabolism, associated with hyperinsulinemia and hyperleptinemia were found. Insulin resistance was evidenced by the raise of HOMA-IR index. Increased insulin and lipid storage were detected at pancreatic and hepatic levels respectively. These findings illustrate the development of a cluster of risk factors (metabolic syndrome) and, for the first time, a decrease of energy expenditure (MR) due to chronic OL infusion.

Atypical antipsychotic drugs induce derangements in glucose homeostasis by acutely increasing glucagon secretion and hepatic glucose output in the rat

AIMS/HYPOTHESIS

Use of the second-generation antipsychotic drugs (SGAs) results in the development of obesity and a type 2 diabetes-like syndrome. We hypothesised that, in addition to the insulin resistance associated with the obesity, the SGAs might have acute effects on glucose metabolism that could contribute to the derangements in glucose metabolism.

METHODS

We investigated the effects of therapeutically relevant levels of three different antipsychotic medications (haloperidol, quetiapine and clozapine) on glucose tolerance, measures of insulin resistance and hepatic glucose production, and on insulin and glucagon secretion in rats.

RESULTS

We found that these drugs induce impaired glucose tolerance in rats that is associated with increased insulin secretion (clozapine>quetiapine>haloperidol) but is independent of weight gain. However, Akt/protein kinase B activation is normal, and at these levels of drug there was no effect on insulin action in fat cells or soleus muscle, and no effect on insulin sensitivity as evaluated by insulin tolerance tests. We show that clozapine induces increased glucose levels following pyruvate and glycerol challenges, indicating an increase in hepatic glucose output (HGO). Increased HGO would in turn increase insulin release and would explain the apparent phenotype mimicking insulin resistance. We provide evidence that this effect could at least in part be mediated by a stimulation of glucagon secretion.

CONCLUSIONS/INTERPRETATION

Our findings indicate that SGAs can cause acute derangements in glucose metabolism that are not caused by a direct induction of insulin resistance but act via an increase in glucagon secretion and thus stimulation of hepatic glucose production.

Antipsychotic drug mechanisms: links between therapeutic effects, metabolic side effects and the insulin signaling pathway

The exact therapeutic mechanism of action of antipsychotic drugs remains unclear. Recent evidence has shown that second-generation antipsychotic drugs (SGAs) are differentially associated with metabolic side effects compared to first-generation antipsychotic drugs (FGAs). Their proclivity to cause metabolic disturbances correlates, to some degree, with their comparative efficacy. This is particularly the case for clozapine and olanzapine. In addition, the insulin signaling pathway is vital for normal brain development and function. Abnormalities of this pathway have been found in persons with schizophrenia and antipsychotic drugs may ameliorate some of these alterations. This prompted us to hypothesize that the therapeutic antipsychotic and adverse metabolic effects of antipsychotic drugs might be related to a common pharmacologic mechanism. This article reviews insulin metabolism in the brain and related abnormalities associated with schizophrenia with the goals of gaining insight into antipsychotic drug effects and possibly also into the pathophysiology of schizophrenia. Finally, we speculate about one potential mechanism of action (that is, functional selectivity) that would be consistent with the data reviewed herein and make suggestions for the future investigation that is required before a therapeutic agent based on these data can be realized.

The antipsychotics clozapine and olanzapine increase plasma glucose and corticosterone levels in rats: comparison with aripiprazole, ziprasidone, bifeprunox and F15063

Several novel antipsychotics activate serotonin 5-HT1A receptors as well as antagonising dopamine D2/3 receptors. Such a pharmacological profile is associated with a lowered liability to produce extrapyramidal side effects and enhanced efficacy in treating negative and cognitive symptoms of schizophrenia. However, 5-HT1A receptor agonists increase plasma corticosterone and many antipsychotics disturb the regulation of glucose. Here, we compared the influence on plasma glucose and corticosterone of acute treatments with 'new generation' antipsychotics which target dopamine D2/3 receptors and 5-HT1A receptors, with that of atypical antipsychotics, and with haloperidol. Olanzapine and clozapine, antipsychotics that are known to produce weight gain and diabetes in humans, both at 10 mg/kg p.o., substantially increased plasma glucose (from 0.8 to 1.7 g/l) at 1 h after administration, an effect that returned to control levels after 4 h. In comparison, F15063 (40 mg/kg p.o.) was without effect at any time point. Olanzapine and clozapine dose-dependently increased plasma glucose concentrations as did SLV313 and SSR181507. Haloperidol and risperidone had modest effects whereas aripiprazole, ziprasidone and bifeprunox, antipsychotics that are not associated with metabolic dysfunction in humans, and F15063 had little or no influence on plasma glucose. The same general pattern of response was found for plasma corticosterone levels. The present data provide the first comparative study of conventional, atypical and 'new generation' antipsychotics on glucose and corticosterone levels in rats. A variety of mechanisms likely underlie the hyperglycemia and corticosterone release observed with clozapine and olanzapine, whilst the balance of dopamine D2/3/5-HT1A interaction may contribute to the less favourable impact of SLV313 and SSR181507 compared with that of bifeprunox and F15063.

A preliminary investigation of alpha-lipoic acid treatment of antipsychotic drug-induced weight gain in patients with schizophrenia

Weight gain and other metabolic disturbances have now become discouraging, major side effects of atypical antipsychotic drugs (AAPDs). The novel strategies required to counteract these serious consequences, however, should avoid modulating the activities of the neurotransmitter receptors involved because those receptors are the therapeutic targets of AAPDs. Adenosine monophosphate-activated protein kinase is an enzyme that plays a pivotal role in energy homeostasis. We hypothesized that alpha-lipoic acid (ALA), which is known to modulate adenosine monophosphate-activated protein kinase activity in the hypothalamus and peripheral tissues, would ameliorate AAPD-induced weight gain. We describe the case series of a 12-week ALA trial in schizophrenia patients treated with AAPDs. Two of 7 enrolled subjects were dropped from the study because of noncompliance and demand for new medication to treat depressive symptoms, respectively. The mean (SD) weight loss was 3.16 (3.20) kg (P = 0.043, last observation carried forward; median, 3.03 kg; range, 0-8.85 kg). On average, body mass index showed a significant reduction (P = 0.028) over the 12 weeks. During the same period, a statistically significant reduction was also observed in total cholesterol levels (P = 0.042), and there was a weak trend toward the reduction in insulin resistance (homeostasis model assessment of insulin resistance) (P = 0.080). Three subjects reported increased energy subjectively. The total scores on the Brief Psychiatric Rating Scale and the Montgomery-Asberg Depression Rating Scale did not vary significantly during the study. These preliminary data suggest the possibility that ALA can ameliorate the adverse metabolic effects induced by AAPDs. To confirm the benefits of ALA, more extended study is warranted.