Receptor occupancy-based analysis of the contributions of various receptors to antipsychotics-induced weight gain and diabetes mellitus

Hypothalamic histamine H1 receptor-AMPK signaling time-dependently mediates olanzapine-induced hyperphagia and weight gain in female rats

Although second-generation antipsychotics induce severe weight gain and obesity, there is a lack of detailed knowledge about the progressive development of antipsychotic-induced obesity. This study examined the hypothalamic histamine H1 receptor and AMP-activated protein kinase (H1R-AMPK) signaling at three distinctive stages of olanzapine-induced weight gain (day 1-12: early acceleration, day 13-28: middle new equilibrium, and day 29-36: late heavy weight maintenance). At the early acceleration stage, the rats were hyperphagic with an underlying mechanism of olanzapine-increased H1R mRNA expression and AMPK phosphorylation (pAMPK), in which pAMPK levels positively correlated with H1R mRNA expression and food intake. At the middle stage, when the rats were no longer hyperphagic, the changes in H1R-AMPK signaling vanished. At the late stage, olanzapine increased H1R mRNA expression but decreased pAMPK which were positively and negatively correlated with weight gain, respectively. These data suggest a time-dependent change of H1R-AMPK signaling, where olanzapine activates AMPK by blocking the H1Rs and causing hyperphagia in the acute phase. The chronic blockade of H1R may contribute to the late stage of olanzapine-induced heavy weight maintenance. However, pAMPK was no longer elevated and actually decreased. This indicates that AMPK acts as an energy sensor and negatively responds to the positive energy balance induced by olanzapine. Furthermore, we showed that an H1R agonist, 2-(3-trifluoromethylphenyl) histamine, can significantly inhibit olanzapine-induced hyperphagia and AMPK activation in the mediobasal hypothalamus in a dose dependent manner. Therefore, lowering H1R-AMPK signaling is an effective treatment for the olanzapine-induced hyperphagia associated with the development of obesity.

Effects of intracerebroventricular (ICV) olanzapine on insulin sensitivity and secretion in vivo: an animal model

The atypical antipsychotics (AAPs) have been associated with an increased risk of type 2 diabetes. While weight gain associated with AAPs is a risk factor for diabetes, preclinical work suggests that among these medications, olanzapine, when given peripherally in a single dose, causes pronounced effects on insulin sensitivity and secretion. Given a critical role of the hypothalamus in control of glucose metabolism, we examined the effect of central administration of olanzapine. Sprague-Dawley rats were treated with a single 75 μg intracerebroventricular (ICV) dose of olanzapine and tested using separate hyperinsulinemic-euglycemic and hyperglycemic clamps. Dosing of olanzapine was established based on inhibition of amphetamine-induced locomotion. In contrast to the single dosing peripheral paradigm, there was no effect of central olanzapine on insulin sensitivity, either with respect to hepatic glucose production or peripheral glucose uptake. Analogous to the peripheral model, a single ICV dose of olanzapine followed by the hyperglycemic clamp decreased insulin (p=0.0041) and C-peptide response (p=0.0039) to glucose challenge as compared to vehicle, mirrored also by a decrease in the steady state glucose infusion rate required to maintain hyperglycemia (p=0.002). In conclusion, we demonstrate novel findings that at least part of the effect of olanzapine on beta-cell function in vivo is central.

Obesity in children with autism spectrum disorder

Research suggests that the prevalence of obesity in children with autism spectrum disorder (ASD) is at least as high as that seen in typically developing children. Many of the risk factors for children with ASD are likely the same as for typically developing children, especially within the context of today's obesogenic environment. The particular needs and challenges that this population faces, however, may render them more susceptible to the adverse effects of typical risk factors, and they may also be vulnerable to additional risk factors not shared by children in the general population, including psychopharmacological treatment, genetics, disordered sleep, atypical eating patterns, and challenges for engaging in sufficient physical activity. For individuals with ASD, obesity and its sequelae potentially represent a significant threat to independent living, self-care, quality of life, and overall health.

PET measurement of receptor occupancy as a tool to guide dose selection in neuropharmacology: are we asking the right questions?

Receptor occupancy studies are becoming commonplace for verifying drug mechanism of action and selecting early development candidates. Positron emission tomography (PET) has been applied to pharmacodynamic (PD) studies in several therapeutic areas including neurology, cardiology, and oncology. Prospective use of PET to define dosing requirements has been proposed particularly for central nervous system (CNS)-targeted drugs; however, correlations with clinical outcomes have been mostly anecdotal and not causally established.

Second generation antipsychotic-induced type 2 diabetes: a role for the muscarinic M3 receptor

Second generation antipsychotics (SGAs) are widely prescribed to treat various disorders, most notably schizophrenia and bipolar disorder; however, SGAs can cause abnormal glucose metabolism that can lead to insulin-resistance and type 2 diabetes mellitus side-effects by largely unknown mechanisms. This review explores the potential candidature of the acetylcholine (ACh) muscarinic M3 receptor (M3R) as a prime mechanistic and possible therapeutic target of interest in SGA-induced insulin dysregulation. Studies have identified that SGA binding affinity to the M3R is a predictor of diabetes risk; indeed, olanzapine and clozapine, SGAs with the highest clinical incidence of diabetes side-effects, are potent M3R antagonists. Pancreatic M3Rs regulate the glucose-stimulated cholinergic pathway of insulin secretion; their activation on β-cells stimulates insulin secretion, while M3R blockade decreases insulin secretion. Genetic modification of M3Rs causes robust alterations in insulin levels and glucose tolerance in mice. Olanzapine alters M3R density in discrete nuclei of the hypothalamus and caudal brainstem, regions that regulate glucose homeostasis and insulin secretion through vagal innervation of the pancreas. Furthermore, studies have demonstrated a dynamic sensitivity of hypothalamic and brainstem M3Rs to altered glucometabolic status of the body. Therefore, the M3R is in a prime position to influence glucose homeostasis through direct effects on pancreatic β-cells and by potentially altering signalling in the hypothalamus and brainstem. SGA-induced insulin dysregulation may be partly due to blockade of central and peripheral M3Rs, causing an initial disruption to insulin secretion and glucose homeostasis that can progressively lead to insulin resistance and diabetes during chronic treatment.

Antipsychotics and the gut microbiome: olanzapine-induced metabolic dysfunction is attenuated by antibiotic administration in the rat

The atypical antipsychotic olanzapine is often associated with serious metabolic side effects including weight gain and increased visceral fat. These adverse events are a considerable clinical problem and the mechanisms underlying them are multifactorial and poorly understood. Growing evidence suggests that the gut microbiota has a key role in energy regulation and disease states such as obesity. Moreover, we recently showed that chronic olanzapine altered the composition of the gut microbiome in the rat. It is thus possible that treatments that alter gut microbiota composition could ameliorate olanzapine-induced weight gain and associated metabolic syndrome. To this end, we investigated the impact of antibiotic-induced alteration of the gut microbiota on the metabolic effects associated with chronic olanzapine treatment in female rats. Animals received vehicle or olanzapine (2 mg kg(-1) per day) for 21 days, intraperitoneal injection, two times daily. Animals were also coadministered vehicle or an antibiotic cocktail consisting of neomycin (250 mg kg(-1) per day), metronidazole (50 mg kg(-1) per day) and polymyxin B (9 mg kg(-1) per day) by oral gavage, daily, beginning 5 days before olanzapine treatment. The antibiotic cocktail drastically altered the microbiota of olanzapine-treated rats, and olanzapine alone was also associated with an altered microbiota. Coadministration of the antibiotic cocktail in olanzapine-treated rats attenuated: body weight gain, uterine fat deposition, macrophage infiltration of adipose tissue, plasma free fatty acid levels, all of which were increased by olanzapine alone. These results suggest that the gut microbiome has a role in the cycle of metabolic dysfunction associated with olanzapine, and could represent a novel therapeutic target for preventing antipsychotic-induced metabolic disease.

Active metabolites as antidepressant drugs: the role of norquetiapine in the mechanism of action of quetiapine in the treatment of mood disorders

Active metabolites of some antipsychotic drugs exhibit pharmacodynamic and pharmacokinetic properties that may be similar to or differ from the original compound and that can be translated by a different profile of responses and interactions to clinical level. Some of these antipsychotics' active metabolites might participate in mechanisms of antidepressant activity, as m-chlorophenylpiperazine (aripiprazole), 9-OH-risperidone and norquetiapine. Norquetiapine exhibits distinct pharmacological activity from quetiapine and plays a fundamental role in its antidepressant efficacy. In this review, we analyze the differential pharmacological aspects between quetiapine and norquetiapine, both from the pharmacokinetic and pharmacodynamic perspectives (affinity for dopaminergic, noradrenegic, and/or serotonergic receptors, etc.), as well as differential neuroprotective role. The pharmacological differences between the two drugs could explain the differential clinical effect, as well as some differences in tolerability profile and drug interactions. The available data are sufficient to arrive at the conclusion that antidepressant activity of quetiapine is mediated, at least in part, by the active metabolite norquetiapine, which selectively inhibits noradrenaline reuptake, is a partial 5-HT1A receptor agonist, and acts as an antagonist at presynaptic α2, 5-HT2C, and 5-HT7 receptors.

Effects of antipsychotic medications on appetite, weight, and insulin resistance

Although clozapine, olanzapine, and other atypical antipsychotic drugs (APDs) have fewer extrapyramidal side effects, they have serious metabolic side effects such as substantial weight gain, intra-abdominal obesity, and type 2 diabetes mellitus. Given that most patients with mental disorders face chronic, even life-long, treatment with APDs, the risks of weight gain/obesity and other metabolic symptoms are major considerations for APD maintenance treatment. This review focuses on the effects of APDs on weight gain, appetite, insulin resistance, and glucose dysregulation, and the relevant underlying mechanisms that may be help to prevent and treat metabolic side effects caused by APD therapy.

Strategies for prevention and management of second generation antipsychotic-induced metabolic side effects

Preventing, minimizing and managing risks associated with second generation antipsychotic (SGA) use in patients with schizophrenia and other psychotic disorders is a priority for clinicians working with this population. Among these risks is metabolic syndrome. As this population exhibits increased rates of obesity, diabetes and atherogenic dyslipidemia compared to the general population, metabolic syndrome deserves serious consideration in patient care planning for managing risks. This article comprehensively reviews different strategies and recommendations for prevention and/or management of metabolic abnormalities associated with the use of SGAs. Baseline screening and follow-up metabolic monitoring as well as education and counseling on risk for SGA-induced weight gain and other metabolic abnormalities, physical activity and healthy diet for weight maintenance/loss should be promoted shortly after initiation of SGAs. In select patients, the clinician can consider simplifying the antipsychotic treatment regimen by switching to an agent with a lower propensity of metabolic side effects or possibly adding metformin for weight loss and glucose metabolism regulation in those experiencing a first episode of schizophrenia. Future research should focus on combinations of interventions and treatment modalities and exploration of novel interventions.

The role of hypothalamic H1 receptor antagonism in antipsychotic-induced weight gain

Treatment with second generation antipsychotics (SGAs), notably olanzapine and clozapine, causes severe obesity side effects. Antagonism of histamine H1 receptors has been identified as a main cause of SGA-induced obesity, but the molecular mechanisms associated with this antagonism in different stages of SGA-induced weight gain remain unclear. This review aims to explore the potential role of hypothalamic histamine H1 receptors in different stages of SGA-induced weight gain/obesity and the molecular pathways related to SGA-induced antagonism of these receptors. Initial data have demonstrated the importance of hypothalamic H1 receptors in both short- and long-term SGA-induced obesity. Blocking hypothalamic H1 receptors by SGAs activates AMP-activated protein kinase (AMPK), a well-known feeding regulator. During short-term treatment, hypothalamic H1 receptor antagonism by SGAs may activate the AMPK-carnitine palmitoyltransferase 1 signaling to rapidly increase caloric intake and result in weight gain. During long-term SGA treatment, hypothalamic H1 receptor antagonism can reduce thermogenesis, possibly by inhibiting the sympathetic outflows to the brainstem rostral raphe pallidus and rostral ventrolateral medulla, therefore decreasing brown adipose tissue thermogenesis. Additionally, blocking of hypothalamic H1 receptors by SGAs may also contribute to fat accumulation by decreasing lipolysis but increasing lipogenesis in white adipose tissue. In summary, antagonism of hypothalamic H1 receptors by SGAs may time-dependently affect the hypothalamus-brainstem circuits to cause weight gain by stimulating appetite and fat accumulation but reducing energy expenditure. The H1 receptor and its downstream signaling molecules could be valuable targets for the design of new compounds for treating SGA-induced weight gain/obesity.

Asenapine, iloperidone and lurasidone: critical appraisal of the most recently approved pharmacotherapies for schizophrenia in adults

This article reviews the pharmacological profile and published efficacy and tolerability/safety data of iloperidone, asenapine and lurasidone, the most recent atypical antipsychotics to be approved in the USA for the treatment of schizophrenia. All three agents are similar in terms of overall efficacy and low propensity for clinically significant weight gain or adverse changes in glycemic or lipid profile. However, these agents differ from one another in terms of formulations, pharmacokinetics, and dosing and nonmetabolic adverse effect profile. For each drug, comparative and real-world effectiveness studies are lacking, as are effectiveness and safety data in elderly, young and pregnant/nursing patients. As such, the exact place of iloperidone, asenapine and lurasidone within the broader antipsychotic armamentarium is currently difficult to establish.

Atypical antipsychotics and diabetic ketoacidosis: a review

RATIONALE

Atypical antipsychotics have been linked to weight gain and type 2 diabetes, but are also associated with diabetic ketoacidosis (DKA), which can occur more acutely and in the absence of weight gain.

OBJECTIVES

Our aim was to review current case reports of DKA in the context of atypical antipsychotic treatment to better understand (a) the scope of the problem, (b) its relationship to different atypical agents, (c) risk factors, (d) long-term outcome, and (e) putative mechanisms of action.

METHOD

Searches in PubMed/Medline, as well as the University of Toronto's Scholar Portal, were performed for all relevant articles/abstracts in English.

RESULTS

Sixty reports, yielding 69 cases, affirm that DKA is a rare but serious risk with almost all atypical antipsychotics; however, liability seems to vary between agents, at least partially mirroring risk of weight gain. Mean age of onset was 36.9 years (range 12-80), with 68 % of cases occurring in males, and 41 % in individuals of African American or African Caribbean descent. Over one third of cases present with either no weight gain or weight loss, and 61 % of these require ongoing treatment for glycemic control. Death occurred in 7.25 % of cases.

CONCLUSION

While the underlying mechanisms are not well understood, antipsychotic-related DKA can occur soon after treatment onset and in the absence of weight gain. Although rare, clinicians must remain vigilant given its acute onset and potential lethality.

Metabolic effects of adjunctive aripiprazole in clozapine-treated patients with schizophrenia

OBJECTIVE

This study examined the effects of adjunctive aripiprazole therapy on metabolism in clozapine-treated patients with schizophrenia.

METHOD

In an 8-week randomized, double-blind, placebo-controlled study, subjects received either aripiprazole (15 mg/day) or placebo. At baseline and week 8, metabolic parameters were assessed by the frequently sampled intravenous glucose tolerance test, nuclear magnetic resonance spectroscopy and whole-body dual-energy X-ray absorptiometry (DXA).

RESULTS

Thirty subjects completed the study (16 in the aripiprazole group and 14 in the placebo group). Glucose effectiveness measured by the frequently sampled intravenous glucose tolerance test improved significantly in the aripiprazole group (0.003 ± 0.006 vs. -0.005 ± 0.007/min, P = 0.010). The aripiprazole group showed significant reductions in both plasma low-density lipoprotein (LDL) levels (-15.1 ± 19.8 vs. 4.4 ± 22.5 mg/dl, P = 0.019) and LDL particle numbers (-376 ± 632 vs. -36 ± 301 nm, P = 0.035). Further, there was a significant reduction in the lean mass (-1125 ± 1620 vs. 607 ± 1578 g, P = 0.011) measured by whole-body DXA scan in the aripiprazole group. All values were expressed as mean ± standard deviation, aripiprazole vs. placebo.

CONCLUSION

Adjunctive therapy with aripiprazole may have some metabolic benefits in clozapine-treated patients with schizophrenia.

Inhibition of mouse brown adipocyte differentiation by second-generation antipsychotics

Brown adipose tissue is specialized to burn lipids for thermogenesis and energy expenditure. Second-generation antipsychotics (SGA) are the most commonly used drugs for schizophrenia with several advantages over first-line drugs, however, it can cause clinically-significant weight gain. To reveal the involvement of brown adipocytes in SGA-induced weight gain, we compared the effect of clozapine, quetiapine, and ziprasidone, SGA with different propensities to induce weight gain, on the differentiation and the expression of brown fat-specific markers, lipogenic genes and adipokines in a mouse brown preadipocyte cell line. On Oil Red-O staining, the differentiation was inhibited almost completely by clozapine (40 µM) and partially by quetiapine (30 µM). Clozapine significantly down-regulated the brown adipogenesis markers PRDM16, C/EBPβ, PPARγ2, UCP-1, PGC-1α, and Cidea in dose- and time-dependent manners, whereas quetiapine suppressed PRDM16, PPARγ2, and UCP-1 much weakly than clozapine. Clozapine also significantly inhibited the mRNA expressions of lipogenic genes ACC, SCD1, GLUT4, aP2, and CD36 as well as adipokines such as resistin, leptin, and adiponectin. In contrast, quetiapine suppressed only resistin and leptin but not those of lipogenic genes and adiponectin. Ziprasidone (10 µM) did not alter the differentiation as well as the gene expression patterns. Our results suggest for the first time that the inhibition of brown adipogenesis may be a possible mechanism to explain weight gain induced by clozapine and quetiapine.

Antipsychotic-induced metabolic and cardiovascular side effects in schizophrenia: a novel mechanistic hypothesis

The use of antipsychotics is hindered by the frequent occurrence of metabolic and cardiovascular side effects, resulting in worsened quality of life and greater mortality as a result of cardiovascular and cerebrovascular disorders in schizophrenia patients than the comparable general population. The various antipsychotics induce extrapyramidal symptoms, impaired glucose and lipid metabolism, weight gain, hypertension and arrhythmias, with variable frequency. Second-generation antipsychotics appear to have several advantages over first-generation antipsychotics, including a claimed better action on cognitive function and the negative symptoms of schizophrenia, and lower frequency of extrapyramidal side effects; however, their use is associated with a greater frequency of metabolic and cardiovascular disturbances. The mechanisms of these important side effects are not well understood, and generic approaches (psychoeducational programmes and symptomatic therapies) have been proposed to limit their severity. Extensive data from the literature indicate that autonomic nervous system dysfunction--intrinsic to schizophrenia and strongly exacerbated by antipsychotic treatment--is the cause of the pervasive metabolic and vascular dysfunctions associated with schizophrenia. In this article, we marshal further literature data to argue that the metabolic and cardiovascular side effects of antipsychotics are primarily mediated by their ability to block peripheral dopamine receptors, which physiologically modulate sympathetic activity. We also propose that these effects might be overcome by providing peripheral dopaminergic stimulation.

Are there different neural mechanisms responsible for three stages of weight gain development in anti-psychotic therapy: temporally based hypothesis

Weight gain as a result of atypical anti-psychotic treatment is a common issue with different atypical anti-psychotic treatments causing differing magnitudes of weight gain. Although differing amounts of weight gain result from different atypical agents little is known about the temporal course of weight gain in anti-psychotic treatment. Specifically is the time course of weight gain comparable across different agents. Therefore this article reviews the temporal course of weight gain for three common atypical anti-psychotics namely; clozapine, olanzapine and risperidone. It is evident that all three of these agents exhibit similar although at distinct magnitudes temporal courses of weight gain. That is an initial rapid increase from baseline to 3 months (stage 1), a steady increase from 3 months to 18 months (stage 2) and a plateau after this point (stage 3) with continued anti-psychotic treatment. It is postulated that each of these stages of weight gain result from distinct neural mechanisms. The hypothesized neural correlates for each stage of weight gain are reviewed and discussed. The article concludes with recommendations for future research.

Reducing olanzapine-induced weight gain side effect by using betahistine: a study in the rat model

Olanzapine is effective at treating multiple domains of schizophrenia symptoms. However, it induces serious metabolic side effects. Antipsychotic drug's antagonistic affinity to histamine H₁ receptors has been identified as a main contributor for weight gain/obesity side effects. This study therefore investigated whether a combined treatment of betahistine (a H₁ receptor agonist and H₃ receptor antagonist) could reduce the body weight/obesity induced by olanzapine. Female Sprague Dawley rats were treated orally with olanzapine (1 mg/kg, t.i.d.) and/or betahistine (2.67 mg/kg, t.i.d.), or vehicle for two weeks. Rats treated with olanzapine exhibited significant body weight gain and increased food intake. Co-treatment of olanzapine with betahistine significantly prevented (-45%) weight gain and reduced feeding efficiency compared to sole olanzapine treatment. Betahistine treatment alone had no effect on weight gain and food intake. Olanzapine reduced locomotor activity, but not betahistine. These findings demonstrate that olanzapine-induced body weight gain can partially be reduced by co-treatment with betahistine. Betahistine has H₃ receptor antagonistic effects to increase histamine release, which may augment its direct agonistic effects on H₁ receptors. These findings have important implications for clinical trials using betahistine to control antipsychotic-induced obesity side effects.

Neurobiological background for the development of new drugs in schizophrenia

Psychopharmacology of schizophrenia has remained static for many years because the mechanisms explored have been basically monoaminergics, primarily focused toward the modification of dopaminergic function and, later on, serotonergic. In fact, most of the antipsychotics introduced in clinical practice in the last years have been antagonists or selective agonists of these receptors (D(2)/5-HT(2)). The exploration of other receptor pathways, and in particular those additionally involved in the action of the paradigmatic "atypical" antipsychotic clozapine (ie, cholinergic and noradrenergic), has not been very significant. Besides, research in the antipsychotics field has developed also by exploring pathways that are beyond the spectrum of clozapine. Among the most promising mechanisms are those based on the glutamatergic hypothesis of schizophrenia (agonists at the glycine-binding modulatory site of the N-methyl-D-aspartate receptor, glycine transporter inhibitors, modulators of the AMPA [α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid] receptor and selective agonists of the metabotropic receptor Glu(2)). Other less classic pathways are also under study and have led to some agents that are found in very early stages of development such as those acting on sigma receptors, cholecystokinin antagonists, neurotensin agonists, neurokinin receptor antagonists, GABAergic (+-aminobutyric acid [GABA]) enhancers, and cannabinoid(gamma-aminobutiric) receptor modulators.

Safety and tolerability of antipsychotic polypharmacy

INTRODUCTION

Antipsychotic polypharmacy (APP), the concomitant use of ≥ 2 antipsychotics, is common in clinical practice. Prior reviews have focused on the efficacy of APP, but no systematic review exists regarding the safety and tolerability of this practice.

AREAS COVERED

A systematic review of adverse effects associated with APP was conducted to prepare this review; case series with ≥ 2 patients, chart reviews, naturalistic, database, cohort and randomized studies that reported on the association between APP in general or specific APP combinations and global or specific adverse effect were included. Methodological limitations of available studies are discussed and recommendations for clinicians and future research are provided.

EXPERT OPINION

Across mostly small and uncontrolled studies, APP has been associated with increased global side effect burden, rates of Parkinsonian side effects, anticholinergic use, hyperprolactinemia, sexual dysfunction, hypersalivation, sedation/somnolence, cognitive impairment and diabetes. Effects on akathisia and mortality were inconclusive. Although some combinations, particularly aripiprazole augmentation of an agent with greater side effect burden, may reduce weight gain, dyslipidemia, hyperprolactinemia and sexual dysfunction, APP should remain a last-resort treatment option after monotherapy, switching and non-antipsychotic combinations have failed. More data are needed to further inform the individualized risk-benefit evaluation of APP.

Expression changes of hypothalamic Ahi1 in mice brain: implication in sensing insulin signaling

Growing evidence suggests that the brain, in particular the hypothalamus, directly senses hormones and nutrients to initiate feeding behavior and metabolic responses in the control of energy homeostasis. However, the molecular mechanisms underlying this important process have remained largely unknown. Our study provides the evidence for the role of Abelson helper integration site 1 (Ahi1) protein as a sensor of insulin signaling in the hypothalamus. We found that fasting increased the expression of hypothalamic Ahi1 which was accompanied by lower levels of circulating insulin compared with satiated mice, while re-feeding decreased the expression of hypothalamic Ahi1 which was accompanied by higher levels of circulating insulin. We also found the up-regulated expression of hypothalamic Ahi1 in high-fat induced obese mice, db/db mice, and streptozotocin induced diabetic mice. In addition, we demonstrated that insulin could decrease the expression of Ahi1 in neuroblastoma cell line N18TG2. Taken together, our results indicate that hypothalamic Ahi1 functions as a sensor of insulin signaling.

Novel olanzapine analogues presenting a reduced H1 receptor affinity and retained 5HT2A/D2 binding affinity ratio

Background

Olanzapine is an atypical antipsychotic drug with high clinical efficacy, but which can cause severe weight gain and metabolic disorders in treated patients. Blockade of the histamine 1 (H₁) receptors is believed to play a crucial role in olanzapine induced weight gain, whereas the therapeutic effects of this drug are mainly attributed to its favourable serotoninergic 2A and dopamine 2 (5HT_2A/D₂) receptor binding affinity ratios.

Results

We have synthesized novel olanzapine analogues 8a and 8b together with the already known derivative 8c and we have examined their respective in vitro affinities for the 5HT_2A, D₂, and H₁ receptors.

Conclusions

We suggest that thienobenzodiazepines 8b and 8c with lower binding affinity for the H₁ receptors, but similar 5HT_2A/D₂ receptor binding affinity ratios to those of olanzapine. These compounds may offer a better pharmacological profile than olanzapine for treating patients with schizophrenia.

Metformin for treatment of antipsychotic-induced weight gain: a randomized, placebo-controlled study

OBJECTIVES

To evaluate the efficacy of metformin for treatment of antipsychotic-induced weight gain.

METHODS

Seventy-two patients with first-episode schizophrenia who gained more than 7% of their predrug weight were randomly assigned to receive 1000 mg/d of metformin or placebo in addition to their ongoing treatment for 12 weeks using a double-blind study design. The primary outcome was change in body weight. The secondary outcomes included changes in body mass index, fasting glucose and insulin, and insulin resistance index.

RESULTS

Of the 72 patients who were randomly assigned, 66 (91.6%) completed treatments. The body weight, body mass index, fasting insulin and insulin resistance index decreased significantly in the metformin group, but increased in the placebo group during the 12-week follow-up period. Significantly more patients in the metformin group lost their baseline weight by more than 7%, which was the cutoff for clinically meaningful weight loss. Metformin was tolerated well by majority patients.

CONCLUSION

Metformin was effective and safe in attenuating antipsychotic-induced weight gain and insulin resistance in first-episode schizophrenia patients. Patients displayed good adherence to metformin.

Effects of olanzapine on muscarinic M3 receptor binding density in the brain relates to weight gain, plasma insulin and metabolic hormone levels

The second generation antipsychotic drug (SGA) olanzapine has an efficacy to treat schizophrenia, but can cause obesity and type II diabetes mellitus. Cholinergic muscarinic M3 receptors (M3R) are expressed on pancreatic β-cells and in the brain where they influence insulin secretion and may regulate other metabolic hormones via vagal innervation of the gastrointestinal tract. Olanzapine's M3R antagonism is an important risk factor for its diabetogenic liability. However, the effects of olanzapine on central M3Rs are unknown. Rats were treated with 0.25, 0.5, 1.0 or 2.0 mg olanzapine/kg or vehicle (3×/day, 14-days). M3R binding densities in the hypothalamic arcuate (Arc) and ventromedial nuclei (VMH), and dorsal vagal complex (DVC) of the brainstem were investigated using [3H]4-DAMP plus pirenzepine and AF-DX116. M3R binding correlations to body weight, food intake, insulin, ghrelin and cholecystokinin (CCK) were analyzed. Olanzapine increased M3R binding density in the Arc, VMH and DVC, body weight, food intake, circulating plasma ghrelin and CCK levels, and decreased plasma insulin and glucose. M3R negatively correlated to insulin, and positively correlated to ghrelin, CCK, food intake and body weight. Increased M3R density is a compensatory up-regulation in response to olanzapine's M3R antagonism. Olanzapine acts on M3R in regions of the brain that control food intake and insulin secretion. Olanzapine's M3R blockade in the brain may inhibit the acetylcholine pathway for insulin secretion. These findings support a role for M3Rs in the modulation of insulin, ghrelin and CCK via the vagus nerve and provide a mechanism for olanzapine's diabetogenic and weight gain liability.

Gender-dependent consequences of chronic olanzapine in the rat: effects on body weight, inflammatory, metabolic and microbiota parameters

RATIONALE

Atypical antipsychotic drugs (AAPDs) such as olanzapine have a serious side effect profile including weight gain and metabolic dysfunction, and a number of studies have suggested a role for gender in the susceptibility to these effects. In recent times, the gut microbiota has been recognised as a major contributor to the regulation of body weight and metabolism. Thus, we investigated the effects of olanzapine on body weight, behaviour, gut microbiota and inflammatory and metabolic markers in both male and female rats.

METHODS

Male and female rats received olanzapine (2 or 4 mg/kg/day) or vehicle for 3 weeks. Body weight, food and water intake were monitored daily. The faecal microbial content was assessed by 454 pyrosequencing. Plasma cytokines (tumour necrosis alpha, interleukin 8 (IL-8), interleuin-6 and interleukin 1-beta (IL-1β)) as well as expression of genes including sterol-regulatory element binding protein-1c and CD68 were analysed.

RESULTS

Olanzapine induced significant body weight gain in the female rats only. Only female rats treated with olanzapine (2 mg/kg) had elevated plasma levels of IL-8 and IL-1β, while both males and females had olanzapine-induced increases in adiposity and evidence of macrophage infiltration into adipose tissue. Furthermore, an altered microbiota profile was observed following olanzapine treatment in both genders.

CONCLUSIONS

This study furthers the theory that gender may impact on the nature of, and susceptibility to, certain side effects of antipsychotics. In addition, we demonstrate, what is to our knowledge the first time, an altered microbiota associated with chronic olanzapine treatment.

Benzothiazoles as probes for the 5HT1A receptor and the serotonin transporter (SERT): a search for new dual-acting agents as potential antidepressants

The synthesis and evaluation of several benzothiazole-based compounds are described in an attempt to identify novel dual-acting 5HT(1A) receptor and SERT inhibitors as new antidepressants. Binding affinities at the 5HT(1A) receptor and the serotonin transporter do not appear to be congruent and other areas of the binding sites would need to be explored in order to improve binding simultaneously at both sites. Compounds 20 and 23 show moderate binding affinity at the 5HT(1A) receptor and the SERT site and thus, have the potential to be further explored as dual-acting agents. In addition, compound 20 binds with low affinity to the dopamine transporter (DAT), the norepinephrine transporter (NET) and 5HT(2C) receptor, which are desirable properties as selectivity for SERT (and not DAT or NET) is associated with an absence of cardiovascular side effects.

Alterations to melanocortinergic, GABAergic and cannabinoid neurotransmission associated with olanzapine-induced weight gain

Background/Aim

Second generation antipsychotics (SGAs) are used to treat schizophrenia but can cause serious metabolic side-effects, such as obesity and diabetes. This study examined the effects of low to high doses of olanzapine on appetite/metabolic regulatory signals in the hypothalamus and brainstem to elucidate the mechanisms underlying olanzapine-induced obesity.

Methodology/Results

Levels of pro-opiomelanocortin (POMC), neuropeptide Y (NPY) and glutamic acid decarboxylase (GAD₆₅, enzyme for GABA synthesis) mRNA expression, and cannabinoid CB1 receptor (CB1R) binding density (using [³H]SR-141716A) were examined in the arcuate nucleus (Arc) and dorsal vagal complex (DVC) of female Sprague Dawley rats following 0.25, 0.5, 1.0 or 2.0 mg/kg olanzapine or vehicle (3×/day, 14-days). Consistent with its weight gain liability, olanzapine significantly decreased anorexigenic POMC and increased orexigenic NPY mRNA expression in a dose-sensitive manner in the Arc. GAD₆₅ mRNA expression increased and CB1R binding density decreased in the Arc and DVC. Alterations to neurotransmission signals in the brain significantly correlated with body weight and adiposity. The minimum dosage threshold required to induce weight gain in the rat was 0.5 mg/kg olanzapine.

Conclusions

Olanzapine-induced weight gain is associated with reduced appetite-inhibiting POMC and increased NPY. This study also supports a role for the CB1R and GABA in the mechanisms underlying weight gain side-effects, possibly by altering POMC transmission. Metabolic dysfunction can be modelled in the female rat using low, clinically-comparable olanzapine doses when administered in-line with the half-life of the drug.

Atypical antipsychotic-induced weight gain: insights into mechanisms of action

Prescriptions for second-generation antipsychotics (SGAs) have surpassed those for first-generation agents in the treatment of schizophrenia and bipolar disorder. While SGAs have the benefit of a much reduced risk of causing movement disorders, they have been associated with weight gain and metabolic effects. These adverse reactions are not uncommon, and threaten to have a significant impact on the patient's health over the long-term treatment that the patient requires. Currently, the aetiology of these effects is not known. This article reviews the data exploring the weight gain phenomenon. The literature was reviewed from searches of PubMed and the references of major articles in the field. The SGAs present a heterogeneous risk for weight gain. In addition, different individuals receiving the same drug can exhibit substantially different weight changes. This pattern suggests that a group of factors are associated with the weight gain phenomenon rather than a single mechanism. Coupled with the genetic profile that the patient brings to the treatment, the risk for SGA-induced weight gain will be different for different drugs and different individuals. Targets for exploration of the weight gain phenomenon include receptor interactions involving serotonin, histamine, dopamine, adrenergic, cannabinoid and muscarinic receptors. The association of SGA-induced weight gain and the role of orexigenic and anorexigenic peptides are reviewed. Also, a brief discussion of genetic factors associated with SGA-induced weight gain is presented, including that of the serotonin 5-HT(2C) receptor gene (HTR2C) and the cannabinoid 1 receptor gene (CNR1). The most promising data associated with SGA-induced weight gain include investigations of the histamine H(1), 5-HT(2A), 5-HT(2C), muscarinic M(3) and adrenergic receptors. In addition, work in the genetic area promises to result in a better understanding of the variation in risk associated with different individuals.

Receptor mechanisms of antipsychotic drug action in bipolar disorder - focus on asenapine

The atypical antipsychotic drugs are considered a first-line treatment for mania in bipolar disorder with many having a proven superiority to the classical mood stabilisers. This review addresses the pharmacological mechanisms underlying this therapeutic efficacy, as well as those mechanisms considered responsible for the adverse effects of antipsychotic drugs, with a particular focus on the recently introduced asenapine. The high efficacy in bipolar mania of haloperidol, a relatively selective dopamine D2-like receptor antagonist, indicates that the one common receptor mechanism underlying antipsychotic effects on mania is antagonism at the D2 receptor. Serotonin receptors are implicated in antidepressant response, and relief of depressed mood in mixed states is likely to involve drug effects at one, or more likely several interacting, serotonin receptors. Asenapine shows a unique breadth of action at these sites, with potential effects at clinical doses at 5HT1A, 1B, 2A, 2C, 6 and 7 receptors. Antagonism at alpha2 adrenoceptors may also be involved. Adverse effects include those classically associated with dopamine D2 receptor blockade, the extrapyramidal side effects (EPS), and which are relatively diminished in the atypical (in comparison with the conventional) antipsychotics. A variety of protective mechanisms against EPS associated with different drugs include low D2 affinity, D2 partial agonism, high 5-HT2A and 2C antagonism. Similar effects at the D2 and 5-HT2C receptors may underlie the low propensity for hyperprolactinaemia of the atypicals, although the strong prolactin-elevating effect of risperidone reflects its relatively high blood/brain concentration ratio, a consequence of it being a substrate for the p-glycoprotein pump. Weight gain is a further concern of antipsychotic treatment of bipolar disorder which is particularly severe with olanzapine. Histamine H1, alpha1 adrenergic and particularly 5-HT2C receptors are implicated in this effect, although the lower propensity for weight gain shown by asenapine which, like olanzapine, binds to these receptors, indicates that other protective receptor mechanisms, or subtle differences in the 5-HT2C receptor-mediated effects, may be important. Of other peripheral and central effects, the pharmacological basis of sedation (H1 receptors) and postural hypotension (alpha1 adrenoceptors) are rather better understood. The relative benefits of atypical antipsychotics like asenapine can be understood from their receptor pharmacology, and this understanding is key to the future development of improved treatment for bipolar disorder.

Effects of antipsychotics with different weight gain liabilities on human in vitro models of adipose tissue differentiation and metabolism

Weight gain and metabolic abnormalities are serious side effects associated with the use of several second generation antipsychotics (SGA). The adipose tissue has been considered a direct SGA target involved in the development of these adverse effects. Recent studies, mainly using murine cells, have suggested that SGA increase both adipogenesis of preadipocytes and lipid accumulation in mature adipocytes. However, to date there has been little research comparing the effects of antipsychotics with different propensities to induce weight gain on human in vitro models of white adipose tissue neoformation and metabolism. The present study aimed to investigate the effects of antipsychotics either strongly associated with weight gain, such as the SGA clozapine and olanzapine, or not, such as the SGA ziprasidone and the classical antipsychotic haloperidol, on proliferation and adipocyte differentiation of human adipose-derived stem cells (ADSCs) and lipogenesis in human mature adipocytes. Whereas ziprasidone induced elevated levels of cell death during adipogenesis and could not be investigated further, we observed that clozapine, olanzapine and haloperidol had slight stimulatory effects on the transcriptional program of ADSCs adipogenesis. However, the observed changes in adipocyte-specific genes were not accompanied by a significant increase in triglyceride accumulation within differentiated adipocytes. Our data also showed that these three antipsychotics displayed inhibitory effects on the proliferation rates of undifferentiated ADSCs. Regarding mature adipocyte metabolism, we observed that olanzapine slightly inhibited insulin-stimulated lipogenesis at the highest concentration used, and haloperidol exerted the strongest inhibitory effects on both basal and insulin-stimulated lipogenesis. Taken together, our results suggest that a direct and potent effect of clozapine and olanzapine on adipose tissue biology is not an important mechanism by which these SGA induce metabolic disturbances in humans. On the other hand, the haloperidol-mediated downregulation of the lipogenic capacity of human adipose tissue may be a possible mechanism contributing to its lower propensity to induce serious metabolic side effects.

Hypothalamic Ahi1 mediates feeding behavior through interaction with 5-HT2C receptor

It is indicated that there are important molecules interacting with brain nervous systems to regulate feeding and energy balance by influencing the signaling pathways of these systems, but relatively few of the critical players have been identified. In the present study, we provide the evidence for the role of Abelson helper integration site 1 (Ahi1) protein as a mediator of feeding behavior through interaction with serotonin receptor 2C (5-HT(2C)R), known for its critical role in feeding and appetite control. First, we demonstrated the co-localization and interaction between hypothalamic Ahi1 and 5-HT(2C)R. Ahi1 promoted the degradation of 5-HT(2C)R through the lysosomal pathway. Then, we investigated the effects of fasting on the expression of hypothalamic Ahi1 and 5-HT(2C)R. Fasting resulted in an increased Ahi1 expression and a concomitant decreased expression of 5-HT(2C)R. Knockdown of hypothalamic Ahi1 led to a concomitant increased expression of 5-HT(2C)R and a decrease of food intake and body weight. Last, we found that Ahi1 could regulate the expression of neuropeptide Y and proopiomelanocortin. Taken together, our results indicate that Ahi1 mediates feeding behavior by interacting with 5-HT(2C)R to modulate the serotonin signaling pathway.

Atypical antipsychotics and effects of muscarinic, serotonergic, dopaminergic and histaminergic receptor binding on insulin secretion in vivo: an animal model

The atypical antipsychotics (AAPs) have been associated with increased risk of type-2 diabetes. Evidence suggests direct, drug-related effects independent of weight gain and although mechanisms underlying this phenomenon are unclear, it has been suggested that the heterogeneous receptor binding profile of the AAPs may influence receptors implicated in glucose metabolism. This study aimed to clarify weight gain-independent mechanisms of AAP-induced changes in insulin secretion by deconstructing their binding profile with representative antagonists. Healthy rats were pretreated with a single subcutaneous dose of darifenacin 6 mg/kg (n=10), a selective M(3) muscarinic antagonist; ketanserin 2mg/kg (n=10), a 5HT(2A) antagonist; raclopride 0.3mg/kg (n=11) a selective D(2)/D(3) antagonist; terfenadine 20mg/kg (n=9) a selective H(1) antagonist; or, vehicle (n=11). Hyperglycemic clamps were employed following injection, providing an index of secretory capacity of pancreatic β-cells. Acute treatment with darifenacin and ketanserin significantly decreased insulin response to glucose challenge as compared to controls, which was confirmed in the darifenacin group by reduced C-peptide levels. Treatment with raclopride resulted in an increased insulin response and a strong tendency to increased C-peptide levels. H(1) blockade did not result in effects on insulin or C-peptide. Results suggest that the effects of antipsychotics on glucose dysregulation may be related to direct inhibitory effects of muscarinic (M(3)) and serotonergic (5HT(2)) antagonism on insulin secretion. Based on the expression of D(2)-like receptors in β-cells, which mediate inhibition of insulin secretion, we propose that prolonged D(2) blockade with antipsychotics may predispose to depletion of insulin stores and an eventual defect in pancreatic compensation.

Pharmacogenetic testing to predict antipsychotic-induced weight gain: a systematic review

Weight gain is an important side effect of antipsychotic drugs. Since the high interindividual difference in weight gain suggests that genetic factors play a role in this weight gain, studies have tried to identify these factors. Most of these studies were carried out in the past few years and focussed largely on receptor polymorphisms, although some tried to explain the variation in weight gain by differences in pharmacokinetics. Unfortunately, the results of these association studies are often conflicting, which makes it hard to apply this genetic knowledge in daily clinical practice. This article summarizes the findings of these association studies and focuses on differences in study methodology in an attempt to explain why study results could have been conflicting. Furthermore, the feasibility of genetic testing in today’s clinical practice is discussed, using a model that consists of four components; analytical validity, clinical validity, clinical utility and ethical, legal and social issues.

Genomewide pharmacogenomic study of metabolic side effects to antipsychotic drugs

Understanding individual differences in the susceptibility to metabolic side effects as a response to antipsychotic therapy is essential to optimize the treatment of schizophrenia. Here, we perform genomewide association studies (GWAS) to search for genetic variation affecting the susceptibility to metabolic side effects. The analysis sample consisted of 738 schizophrenia patients, successfully genotyped for 492K single nucleotide polymorphisms (SNPs), from the genomic subsample of the Clinical Antipsychotic Trial of Intervention Effectiveness study. Outcomes included 12 indicators of metabolic side effects, quantifying antipsychotic-induced change in weight, blood lipids, glucose and hemoglobin A1c, blood pressure and heart rate. Our criterion for genomewide significance was a pre-specified threshold that ensures, on average, only 10% of the significant findings are false discoveries. A total of 21 SNPs satisfied this criterion. The top finding indicated that a SNP in Meis homeobox 2 (MEIS2) mediated the effects of risperidone on hip circumference (q=0.004). The same SNP was also found to mediate risperidone's effect on waist circumference (q=0.055). Genomewide significant finding were also found for SNPs in PRKAR2B, GPR98, FHOD3, RNF144A, ASTN2, SOX5 and ATF7IP2, as well as in several intergenic markers. PRKAR2B and MEIS2 both have previous research indicating metabolic involvement, and PRKAR2B has previously been shown to mediate antipsychotic response. Although our findings require replication and functional validation, this study shows the potential of GWAS to discover genes and pathways that potentially mediate adverse effects of antipsychotic medication.

Association of genetic variants of the histamine H1 and muscarinic M3 receptors with BMI and HbA1c values in patients on antipsychotic medication

RATIONALE

Antipsychotic affinity for the histamine H1 receptor and the muscarinic M3 receptor have been associated with the side effects weight gain, and development of diabetes, respectively.

OBJECTIVES

We investigated polymorphisms of the histamine H1 (HRH1) and muscarinic acetylcholine receptor M3 (CHRM3) receptor genes for an association with body mass index (BMI) and glycated hemoglobin (HbA1c).

METHODS

We included 430 Caucasian patients with a non-affective psychotic disorder using antipsychotics for at least 3 months. Primary endpoints of the study were cross-sectionally measured BMI and HbA1c; secondary endpoints were obesity and hyperglycaemia. Two single-nucleotide polymorphisms (SNPs) in the HRH1 gene, rs346074 and rs346070, and one SNP in the CHRM3 gene, rs3738435, were genotyped. Our primary hypothesis in this study was an interaction between genotype on BMI and antipsychotic affinity for the H1 and M3 receptor.

RESULTS

A significant association of interaction between haplotype rs346074-rs346070 and BMI (p value 0.025) and obesity (p value 0.005) in patients using high-H1 affinity antipsychotics versus patients using low-H1 affinity antipsychotics was found. There was no association of CHRM3 gene variant rs3738435 with BMI, and we observed no association with HbA1c or hyperglycaemia in any of the variants.

CONCLUSIONS

This study, for the first time, demonstrates a significant association between HRH1 variants and BMI in patients with a psychotic disorder using antipsychotics. In future, genotyping of HRH1 variants may help predicting weight gain in patients using antipsychotics.

[Drug-induced hyperglycemia: a study in the French pharmacovigilance database]

OBJECTIVE

To analyse drugs inducing hyperglycemia by using data reported to the French spontaneous reporting system and recorded in the French PharmacoVigilance Database (FPVD).

METHODS

All cases with a report of hyperglycemia and/or diabetes in the French database between 1985 and 2008 were included in the study. We estimated the risk of hyperglycemia linked to drugs by the case/non-case method. Cases were reports including hyperglycemia and non cases all other reports. This risk was estimated through calculation of reporting odds ratios (ROR).

RESULTS

During this period, 1219 reports including the words "hyperglycemia and/or diabetes" were registered (0.34% of the database). This adverse drug reaction occurred 1 fold over 4 in diabetics or as a part of HIV infection. Effect was "serious" in approximatively 50% of cases. We found an increase of risk during exposition with methylprednisolone [ROR=43.5; 95% CI (37.3-50.8)], tacrolimus [ROR=25; 95% CI (17.9-34.8)], olanzapine [ROR=19.9; 95% CI (14.9-26.5)], prednisone [ROR=18.9; 95% CI (15.7-22.8)] or pentamidine [ROR=15.4; 95% CI (8.2-28.3)].

CONCLUSION

Drug classes most frequently found in FPVD linked to hyperglycemia are antiretroviral, steroidal anti-inflammatory, second generation neuroleptic, immunosuppressive and diuretic drugs.

Weight gain, schizophrenia and antipsychotics: new findings from animal model and pharmacogenomic studies

Excess body weight is one of the most common physical health problems among patients with schizophrenia that increases the risk for many medical problems, including type 2 diabetes mellitus, coronary heart disease, osteoarthritis, and hypertension, and accounts in part for 20% shorter life expectancy than in general population. Among patients with severe mental illness, obesity can be attributed to an unhealthy lifestyle, personal genetic profile, as well as the effects of psychotropic medications, above all antipsychotic drugs. Novel "atypical" antipsychotic drugs represent a substantial improvement on older "typical" drugs. However, clinical experience has shown that some, but not all, of these drugs can induce substantial weight gain. Animal models of antipsychotic-related weight gain and animal transgenic models of knockout or overexpressed genes of antipsychotic receptors have been largely evaluated by scientific community for changes in obesity-related gene expression or phenotypes. Moreover, pharmacogenomic approaches have allowed to detect more than 300 possible candidate genes for antipsychotics-induced body weight gain. In this paper, we summarize current thinking on: (1) the role of polymorphisms in several candidate genes, (2) the possible roles of various neurotransmitters and neuropeptides in this adverse drug reaction, and (3) the state of development of animal models in this matter. We also outline major areas for future research.

Effects of simvastatin and 6-hydroxydopamine on histaminergic H1 receptor binding density in rat brains

Statins have been widely used for the treatment of a variety of medical conditions including psychoneurological disorders beyond their original use in lowering cholesterol. Histamine receptors play an important role in the regulation of neural activity, however, it is unknown whether statins act on histamine receptors, particularly for their neural regulatory effects. This study examined the effects of simvastatin and 6-hydroxydopamine (6-OHDA) lesions on histamine H1 receptors using [(3)H] pyrilamine binding autoradiography. Compared to the saline group, simvastatin (1 mg/kg/day) significantly decreased H1 receptor bindings in the primary motor cortex (M1), ventromedial hypothalamic nucleus (VMH), caudate putamen (CPu), accumbens core (AcbC) and prefrontal cortex (PfC) (all p<0.05); however 10 mg/kg/day simvastatin increased H1 receptor density only in the medial amygdaloid nucleus (Mep) (p<0.05), but had no significant effect in other regions examined. The 6-OHDA lesion did not alter H1 receptor binding density in most brain areas, except a trend decrease in the hippocampus (p=0.07) and a trend increase in the cingulate cortex (p=0.06). These results suggested that simvastatin has different effects on the H1 receptors in different rat brain regions depending on the doses. Therefore, simvastatin can modulate histaminergic neurotransmission in the brain, and support the role of H1 receptors in psychoneurological disorders.

Association between the 1291-C/G polymorphism in the adrenergic α-2a receptor and the metabolic syndrome

The prevalence of the metabolic syndrome is increased in patients with schizophrenia compared with the general population. The strong interindividual differences in susceptibility to developing the metabolic syndrome suggests that the genetic makeup is a modulating factor. Part of the genetic puzzle can possibly be explained by variations in the gene coding for the adrenergic α-2a receptor (ADRA2A) because this receptor plays an important role in lipolysis. Three studies have found an association between the α-2a 1291-C/G polymorphism and antipsychotic induced weight gain, with conflicting results between whites and Asians. No studies have been published investigating the association between the 1291-C/G polymorphism and the metabolic syndrome. The primary objective of this cross-sectional study was to investigate the association between the ADRA2A 1291-C/G polymorphism and the metabolic syndrome in 470 patients using antipsychotic drugs. There was no significant association between carriership of the variant 1291-G allele and prevalence of the metabolic syndrome (odds ratio, 0.73; 95% confidence interval, 0.49-1.15). Exploratory analysis showed an association between carriership of the variant 1291-G allele and a reduced prevalence of the metabolic syndrome in patients not currently using antipsychotics (odds ratio, 0.05; 95% confidence interval, 0.003-0.97; P = 0.048). In conclusion, this study shows that the ADRA2A 1291-C/G polymorphism does not seem to be a strong predictor for long-term occurrence of the metabolic syndrome in antipsychotic using patients. Studies investigating this association using a prospective, or retrospective, design, as well as studies investigating this association in a nonpsychiatric population, are warranted.

The potential role of appetite in predicting weight changes during treatment with olanzapine

BACKGROUND

Clinically significant weight gain has been reported during treatment with atypical antipsychotics. It has been suggested that weight changes in patients treated with olanzapine may be associated with increased appetite.

METHODS

Data were used from adult patients for whom both appetite and weight data were available from 4 prospective, 12- to 24-week clinical trials. Patients' appetites were assessed with Eating Behavior Assessment (EBA, Study 1), Platypus Appetite Rating Scale (PARS, Study 2), Eating Inventory (EI, Study 3), Food Craving Inventory (FCI, Study 3), and Eating Attitude Scale (EAS, Study 4).

RESULTS

In Studies 1 (EBA) and 4 (EAS), patients who reported overall score increases on appetite scales, indicating an increase in appetite, experienced the greatest overall weight gains. However, in Studies 2 (PARS) and 3 (EI, FCI), patients who reported overall score increases on appetite scales did not experience greater weight changes than patients not reporting score increases. Early weight changes (2-4 weeks) were more positively correlated with overall weight changes than early or overall score changes on any utilized appetite assessment scale. No additional information was gained by adding early appetite change to early weight change in correlation to overall weight change.

CONCLUSIONS

Early weight changes may be a more useful predictor for long-term weight changes than early score changes on appetite assessment scales.

CLINICAL TRIALS REGISTRATION

This report represents secondary analyses of 4 clinical studies. Studies 1, 2, and 3 were registered at http://clinicaltrials.gov/ct2/home, under NCT00190749, NCT00303602, and NCT00401973, respectively. Study 4 predates the registration requirements for observational studies that are not classified as category 1 observational studies.

Effects of atypical antipsychotics and haloperidol on PC12 cells: only aripiprazole phosphorylates AMP-activated protein kinase

By converting changes in intracellular energy status to changes in cell membrane polarization, ATP-sensitive K(+) (K(ATP)) channels in hypothalamic appetite-regulating neurons play a critical role in linking neuronal electrochemical function, metabolic and energy status, and feeding behavior. Most atypical antipsychotics (AAPs) increase the appetite of patients with schizophrenia and thus cause obesity. This study aimed to explain the mechanism underlying AAP-induced appetite stimulation, based on the fact that the efficiency of fatty acid uptake into mitochondria generating ATP through β-oxidation is determined by the rate of fatty acid synthesis. Using PC12 cells exposed to clozapine, olanzapine, risperidone, quetiapine, ziprasidone, aripiprazole, and haloperidol, we measured intracellular ATP and mRNA and protein expression of enzymes and related substances involved in fatty acid synthesis and K(ATP) channel function. Forty-eight-hour treatment of cells with 50 μM aripiprazole in 5.6 mM glucose decreased intracellular ATP. Only 50 μM aripiprazole phosphorylated AMP-activated protein kinase (AMPK); none of the other antipsychotics did so to a detectable level. Expression of carnitine palmitoyltransferase 1a, uncoupling protein 2, and sulfonylurea receptor 1 was unaffected by the antipsychotics, although expression of their mRNA was affected by AAPs. Pyrilamine (H(1) receptor antagonist), ketanserin (5HT(2) receptor antagonist), and raclopride (D(2) receptor antagonist) alone or in combination had no effect on expression of the aforementioned proteins. Therefore, although this study did not differentiate orexigenic and non-orexigenic AAPs, it suggests that aripiprazole is unique in its ability to activate AMPK.

Do atypical antipsychotic drugs reduce the risk of ischemic heart disease and mortality? Possible role of 5-HT2A receptor blockade

A recent Finnish study reported that long-term cumulative exposure to any antipsychotic treatment was related to lower mortality than was no drug exposure. We hypothesize that the antipsychotic 5-HT2A receptor blockade might protect from ischemic heart disease and buffer the deleterious metabolic effects of antipsychotics. The 5-HT2A receptor may be involved in vascular smooth muscle contraction, coronary artery spasms, platelet aggregation and thrombus formation. 5-HT2A receptor blockade might protect from ischemic heart disease by decreasing platelet aggregation and myocardium hypertrophy. Long-term follow-up studies are needed to clearly establish the long-term contribution of the various antipsychotic drugs to ischemic heart disease, and to explore our hypothesis that 5-HT2A receptor blockade may be protective for cardiovascular disease.

Changes in weight and body mass index during treatment with melperone, clozapine and typical neuroleptics

Melperone is an atypical antipsychotic drug that has been reported to be effective in treatment-resistant schizophrenia and L-DOPA psychosis. There are limited data concerning its effect on weight or body mass index (BMI). Weight and BMI were retrospectively compared in patients with schizophrenia treated with melperone (n=34), clozapine (n=225), or typical neuroleptics (n=74) for up to 3 months. Clozapine resulted in significant increases in weight and BMI from baseline to 6 weeks and 3 months. Neither melperone nor typical neuroleptics resulted in significant weight gain at either time point. Melperone did not result in significant increases in BMI. Weight and BMI were significantly lower with melperone compared with clozapine, but similar to typical neuroleptics. The proportion of melperone patients who experienced a >or=7% weight increase was lower than that in patients treated with clozapine and similar to that in patients treated with typical neuroleptics. Percent change in weight and BMI predicted improvement in BPRS total scores at 3 months in the clozapine group, but not in the melperone or typical neuroleptic groups. Because of the relationship between BMI and cardiovascular risk, melperone deserves further study as both a first line treatment and as an alternative to clozapine in refractory schizophrenia.

The tempted brain eats: pleasure and desire circuits in obesity and eating disorders

What we eat, when and how much, all are influenced by brain reward mechanisms that generate "liking" and "wanting" for foods. As a corollary, dysfunction in reward circuits might contribute to the recent rise of obesity and eating disorders. Here we assess brain mechanisms known to generate "liking" and "wanting" for foods and evaluate their interaction with regulatory mechanisms of hunger and satiety, relevant to clinical issues. "Liking" mechanisms include hedonic circuits that connect together cubic-millimeter hotspots in forebrain limbic structures such as nucleus accumbens and ventral pallidum (where opioid/endocannabinoid/orexin signals can amplify sensory pleasure). "Wanting" mechanisms include larger opioid networks in nucleus accumbens, striatum, and amygdala that extend beyond the hedonic hotspots, as well as mesolimbic dopamine systems, and corticolimbic glutamate signals that interact with those systems. We focus on ways in which these brain reward circuits might participate in obesity or in eating disorders.

[Non-pharmacological interventions for weight gain in patients with schizophrenia taking antipsychotics]

INTRODUCTION

Schizophrenic patients have a higher prevalence of obesity than the general population. There are several factors implicated in weight gain, including poor dietary conditions, sedentary lifestyle and antipsychotic drugs use. Obesity is also associated with metabolic disturbances such as diabetes mellitus. Weight gain interventions are necessary in this population, especially non-pharmacological interventions.

OBJECTIVE

To review the non-pharmacological interventions for weight gain management in patients with schizophrenia.

METHODS

Eight clinical trials and four open-label studies using these interventions were found. The methodology, strength and limitations of the studies were reviewed.

CONCLUSIONS

Non-pharmacological interventions seem to have an important effect on weight gain prevention and control, and should be encouraged and adapted to patients and in mental health institution's reality.

Association study of polymorphisms in insulin induced gene 2 (INSIG2) with antipsychotic-induced weight gain in European and African-American schizophrenia patients

OBJECTIVE

Atypical antipsychotic drugs, in particular clozapine and olanzapine, influence cellular lipogenesis and are associated with metabolic side effects including weight gain. Insulin induced gene 2 (INSIG2) mediates feedback control of lipid synthesis and polymorphisms in the gene (rs17587100, rs10490624 and rs17047764) have been associated with antipsychotic induced weight gain. In this study we intended to replicate these findings in an independent patient population.

METHODS

All three polymorphisms as well as an additional polymorphism (rs7566605) were genotyped in 154 patients who underwent treatment for chronic schizophrenia with one of four antipsychotics (clozapine, olanzapine, haloperidol or risperidone). Patients were evaluated for antipsychotic induced weight gain during treatment for up to 14 weeks.

RESULTS

We did not observe any significant allelic, genotypic or haplotypic association of the polymorphisms with antipsychotic induced weight gain in the patients of European ancestry (p > 0.05). In the patients of African ancestry, no haplotypic association was observed but a trend of allelic association with the C allele of rs7566605 and genotypic association with the 'GC' genotype in rs17047764 was observed (p = 0.02; p(Bonferroni) = 0.225).

CONCLUSION

We were unable to replicate significant associations in patients of European ancestry. However, we observed a marginal effect of the rs17047764 and rs7566605 in the African-American sample. Since the latter observations were generated in a relatively small sample set, further replication studies are warranted.

Metformin for atypical antipsychotic-induced weight gain and glucose metabolism dysregulation: review of the literature and clinical suggestions

Individuals receiving certain atypical antipsychotic medications are at risk of gaining weight and developing metabolic problems. There are no established drug treatments to prevent or counter these problems. However, the antihyperglycaemic agent metformin appears promising in some recent studies and we review the literature that evaluates metformin for limiting or reversing atypical antipsychotic drug-induced weight gain and glucose metabolism dysregulation. These studies suggest that metformin is beneficial if started early in antipsychotic drug treatment. Metformin has also been shown to prevent or delay the onset of type 2 diabetes mellitus in high-risk individuals from the general population. Based on these findings, we identify antipsychotic drug-treated patients who might benefit from metformin therapy and offer clinical guidelines for its use. Further long-term studies are needed to extend our observations and improve this strategy.