Quetiapine lowers sympathetic and hyperthermic reactions due to cerebral injection of orexin A

Cannabidiol as a candidate pharmacotherapy for sleep disturbance in alcohol use disorder

Among individuals with alcohol use disorder (AUD), it is estimated that the majority suffer from persistent sleep disturbances for which few candidate medications are available. Our aim wass to critically review the potential for cannabidiol (CBD) as a treatment for AUD-induced sleep disturbance. As context, notable side effects and abuse liability for existing medications for AUD-induced sleep disturbance reduce their clinical utility. CBD modulation of the endocannabinoid system and favorable safety profile have generated substantial interest in its potential therapeutic use for various medical conditions. A number of preclinical and clinical studies suggest promise for CBD in restoring the normal sleep-wake cycle and in enhancing sleep quality in patients diagnosed with AUD. Based on its pharmacology and the existing literature, albeit primarily preclinical and indirect, CBD is a credible candidate to address alcohol-induced sleep disturbance. Well-designed RCTs will be necessary to test its potential in managing this challenging feature of AUD.

The role of baseline insomnia in moderating the hypnotic properties of quetiapine

INTRODUCTION

The primary aim of this study was to investigate the effect of quetiapine on insomnia and alcohol craving (craving) in subjects with co-occurring insomnia and AUD.

METHODS

Insomnia was assessed with the Insomnia Severity Index (ISI) and craving with the Penn Alcohol Craving Scale (PACS, primary) and Obsessive-Compulsive Drinking Scale (OCDS, secondary). A multivariable model adjusted for covariates (N = 123) evaluated the relationship between craving (PACS and OCDS total scores) and insomnia (ISI total score). To simultaneously assess the effects of treatment arm allocation and insomnia status, subjects (N = 115) were stratified into 4 groups, quetiapine-insomnia(N = 38), quetiapine-No insomnia(N = 19), placebo-insomnia(N = 38), and placebo-No insomnia(N = 20). Linear mixed-effects regression models adjusted for covariates compared the trajectories of ISI, PACS, and OCDS total scores across 12 weeks of treatment and at post-treatment follow-up at week 24, between the four groups.

RESULTS

The ISI total score was positively associated with the PACS (p = 0.006) and OCDS (p = 0.001) total scores in the multivariable models. In the longitudinal analysis, when compared to the three other groups, subjects with insomnia treated with quetiapine showed a marked reduction in their insomnia scores with a return of insomnia after stopping treatment. There was no significant difference between the groups for the PACS and OCDS total score trajectories.

DISCUSSION

Although craving is associated with insomnia, treatment with quetiapine may improve insomnia but not craving in patients with co-occurring AUD and insomnia.

The Relationship between Alcohol Craving and Insomnia Symptoms in Alcohol-Dependent Individuals

AIM

This preliminary investigation evaluated the link between alcohol craving and insomnia in actively drinking patients with alcohol dependence (AD).

METHODS

We conducted a secondary analysis of data from a clinical trial of treatment-seeking patients with AD who drank heavily (N = 61). The Penn Alcohol Craving Scale (PACS) evaluated alcohol craving, and the Short Sleep Index (SSI) assessed insomnia symptoms. We used linear regression models for baseline cross-sectional assessments. Linear mixed effects regression models evaluated craving scores longitudinally across insomnia groups (+/-), and insomnia scores longitudinally across craving groups(high/low). These longitudinal analyses were conducted separately in those treated with placebo (N = 32) and quetiapine (N = 29).

RESULTS

The mean (standard deviation) for PACS total score was 15.9 (8.5) and for SSI was 2.1 (2.3). Alcohol craving was associated with the insomnia symptom of difficulty falling asleep (P = 0.03; effect size = -0.7) and with the SSI total score (P = 0.04, effect size = -0.7). In the longitudinal analysis, insomnia+ subjects had consistently higher PACS total scores, relative to the insomnia- group. The PACS score demonstrated significant group × time interactions in both treatment groups. Insomnia+ individuals demonstrated a relatively steeper rate of decline in the craving with quetiapine treatment (P = 0.03). Insomnia- individuals in the placebo group demonstrated a transient reduction in craving until week 8, followed by an increase in scores(P = 0.004). The SSI score did not demonstrate any interactive effect over time across the craving groups in either treatment arm.

CONCLUSION

Insomnia was associated with higher alcohol craving and quetiapine differentially reduced craving in those with insomnia.

Olanzapine-induced endoplasmic reticulum stress and inflammation in the hypothalamus were inhibited by an ER stress inhibitor 4-phenylbutyrate

Antipsychotics are the most important treatment for schizophrenia. However, antipsychotics, particularly olanzapine and clozapine, are associated with severe weight gain/obesity side-effects. Although numerous studies have been carried out to identify the exact mechanisms of antipsychotic-induced weight gain, it is still important to consider other pathways. Endoplasmic reticulum (ER) stress signaling and its associated inflammation pathway is one of the most important pathways involved in regulation of energy balance. In the present study, we examined the role of hypothalamic protein kinase R like endoplasmic reticulum kinase- eukaryotic initiation factor 2α (PERK-eIF2α) signaling and the inflammatory IkappaB kinase β- nuclear factor kappa B (IKKβ-NFκB) signaling pathway in olanzapine-induced weight gain in female rats. In this study, we found that olanzapine significantly activated PERK-eIF2α and IKKβ-NFκB signaling in SH-SY5Y cells in a dose-dependent manner. Olanzapine treatment for 8 days in rats was associated with activated PERK-eIF2α signaling and IKKβ-NFκB signaling in the hypothalamus, accompanied by increased food intake and weight gain. Co-treatment with an ER stress inhibitor, 4-phenylbutyrate (4-PBA), decreased olanzapine-induced food intake and weight gain in a dose- and time-dependent manner. Moreover, 4-PBA dose-dependently inhibited olanzapine-induced activated PERK-eIF2α and IKKβ-NFκB signaling in the hypothalamus. These results suggested that hypothalamic ER stress may play an important role in antipsychotic-induced weight gain.

Antipsychotics-induced metabolic alterations: Recounting the mechanistic insights, therapeutic targets and pharmacological alternatives

Atypical antipsychotics (AAPs) are the drug of choice in the management of mental illnesses by virtue of their advantage over typical antipsychotics i.e. least tendency of producing extrapyramidal motor symptoms (EPS) or pseudoparkinsonism. Despite the clinical efficacy, AAPs produces troublesome adverse effects, particularly hyperphagia, hyperglycemia, dyslipidemia weight gain, diabetes mellitus, insulin resistance and QT prolongation which further develops metabolic and cardiac complications with subsequent reduction in life expectancy, poor patient compliance, and sudden death. AAPs-induced weight gain and metabolic alterations are increasing at an alarming rate and became an utmost matter of concern for psychopharmacotherapy. Diverse underlying mechanisms have been explored such as the interaction of AAPs with neurotransmitter receptors, alteration in food reward anticipation behavior, altered expressions of hypothalamic orexigenic and anorexigenic neuropeptides, histamine H₁ receptor-mediated hypothalamic AMP-activated protein kinase (AMPK) activation, increased blood leptin, ghrelin, pro-inflammatory cytokines. Antipsychotics induced imbalance in energy homeostasis, reduction in energy expenditure which is linked to altered expression of uncoupling proteins (UCP-1) in brown adipose tissue and reduced hypothalamic orexin expressions are emerging insights. In addition, alteration in gut-microbiota and subsequent inflammation, dyslipidemia, obesity, and diabetes after AAPs treatment are also associated with weight gain and metabolic alterations. Oral hypoglycemics and lipid-lowering drugs are mainly prescribed in the clinical management of weight gain associated with AAPs while many other pharmacological and nonpharmacological interventions also have been explored in different clinical and preclinical studies. In this review, we critically discuss the current scenario, mechanistic insights, biomarkers, and therapeutic alternatives for metabolic alterations associated with antipsychotics.

Orexin-A Levels in Relation to the Risk of Metabolic Syndrome in Patients with Schizophrenia Taking Antipsychotics

BACKGROUND

The role of orexin-A in regulating metabolic homeostasis has been recognized, but its association with antipsychotic-induced metabolic abnormalities remains unclear. We investigated the association between orexin-A levels and metabolic syndrome in patients with schizophrenia treated with clozapine or less obesogenic antipsychotics compared with nonpsychiatric controls.

METHODS

Plasma orexin-A levels and metabolic parameters were determined in 159 patients with schizophrenia: 109 taking clozapine; 50 taking aripiprazole, amisulpride, ziprasidone, or haloperidol; and 60 nonpsychiatric controls.

RESULTS

Orexin-A levels were significantly higher in the group taking less obesogenic antipsychotics, followed by the clozapine group and the controls (F=104.6, P<.01). Higher orexin-A levels were correlated with better metabolic profiles in the patient groups but not in the controls. Regression analyses revealed that the patients with higher orexin-A levels had significantly lower risk of metabolic syndrome (adjusted odds ratio [OR]=0.04, 95% CI: 0.01-0.38 for the 2nd tertile; OR=0.04, 95% CI: 0.01-0.36 for the 3rd tertile, compared with the first tertile), after adjustment for age, sex, smoking history, types of antipsychotics (clozapine vs less obesogenic antipsychotics), duration of antipsychotic treatment, and disease severity.

CONCLUSIONS

Our results revealed that the orexin-A level was upregulated in patients with schizophrenia treated with antipsychotics, especially for the group taking less obesogenic antipsychotics. Furthermore, higher orexin-A levels were independently associated with better metabolic profiles. These observations suggest that an upregulation of orexin-A has a protective effect against the development of metabolic abnormalities in patients with schizophrenia receiving antipsychotic treatment.

Functional Changes of Orexinergic Reaction to Psychoactive Substances

It is becoming increasingly apparent the importance of the central nervous system (CNS) as the major contributor to the regulation of systemic metabolism. Antipsychotic drugs are used often to treat several psychiatric disorders, including schizophrenia and bipolar disorder However, antipsychotic drugs prescription, particularly the second-generation ones (SGAs), such as clozapine and olanzapine, is related to a considerable weight gain which usually leads to obesity. The aim of this paper is to assess the influence of orexin A on sympathetic and hyperthermic reactions to several neuroleptic drugs. Orexin A is a neuropeptide which effects both body temperature and food intake by increasing sympathetic activity. Orexin A-mediated hyperthermia is reduced by haloperidol and is blocked by clozapine and olanzapine. Orexin A-mediated body temperature elevation is increased by risperidone. These hyperthermic effects are delayed by quietapine. In this paper, it is discussed the orexinergic pathway activation by neuroleptic drugs and its influence on human therapeutic strategies. With the aim to determine that neuroleptic drugs mediate body temperature control through to the orexinergic system, we summarized our previously published data. Psychiatric disorders increase the risk of developing metabolic disorders (e.g., weight gain, increased blood pressure, and glucose or lipid levels). Therefore, the choice of antipsychotic drug to be prescribed, based on the relevant risks and benefits of each individual drug, has an essential role in human health prevention.

Role of Sex Hormones in the Control of Vegetative and Metabolic Functions of Middle-Aged Women

Aims: In women's life, menopause is characterized by significant physiological changes often associated with an increase in body mass and obesity-associated sicknesses. Numerous researches described interdependencies of estrogen deficiency, aging, and resting energy expenditure (REE) downfall in the obesity correlated with the menopause. The aim of this study was to determining whether healthy, obese menopausal women underwent HRT treatment, showed changes in their REE, autonomic asset, and assessment of oxidative stress in comparison with obese pre- and post-menopausal women.

Methodology: In this study, we measured the body composition, the REE, the oxidative stress, the diet assimilation, and the autonomic nervous system activity in three groups: pre-menopause women (n = 50), post-menopause women following hormone-replacement therapy (HRT; n = 50), and post-menopause women not following HRT (n = 50).

Results: In the group with HRT a significant increase of the sympathetic activity and REE was described. Finally this group showed a notable increment of oxidative stress compared with the others, and utilizing BIA instrument, the free fat mass was increased respect to the fat mass of obese women.

Conclusion: The study highlights the importance of the HRT-related physiological changes that influence body weight in menopause women. This results are important because have a practical implications for prevention and/or treatment of the obesity.

Neuropeptide S increases motor activity and thermogenesis in the rat through sympathetic activation

The central role of neuropeptide S (NPS), identified as the endogenous ligand for GPR154, now named neuropeptide S receptor (NPSR), has not yet been fully clarified. We examined the central role of NPS for body temperature, energy expenditure, locomotor activity and adrenal hormone secretion in rats. Intracerebroventricular (icv) injection of NPS increased body temperature in a dose-dependent manner. Energy consumption and locomotor activity were also significantly increased by icv injection of NPS. In addition, icv injection of NPS increased the peripheral blood concentration of adrenalin and corticosterone. Pretreatment with the β1- and β2-adrenergic receptor blocker timolol inhibited the NPS-induced increase of body temperature. The expression of both NPS mRNA in the brainstem and NPSR mRNA in the hypothalamus showed a nocturnal rhythm with a peak occurring during the first half of the dark period. To examine whether the endogenous NPS is involved in regulation of body temperature, NPSR antagonist SHA68 was administered one hour after darkness. SHA68 attenuated the nocturnal rise of body temperature. These results suggest that NPS contributes to the regulation of the sympathetic nervous system.

Role of Autonomic Nervous System and Orexinergic System on Adipose Tissue

Adipose tissue, defined as white adipose tissue (WAT) and brown adipose tissue (BAT), is a biological caloric reservoir; in response to over-nutrition it expands and, in response to energy deficit, it releases lipids. The WAT primarily stores energy as triglycerides, whereas BAT dissipates chemical energy as heat. In mammals, the BAT is a key site for heat production and an attractive target to promote weight loss. The autonomic nervous system (ANS) exerts a direct control at the cellular and molecular levels in adiposity. The sympathetic nervous system (SNS) provides a complex homeostatic control to specifically coordinate function and crosstalk of both fat pads, as indicated by the increase of the sympathetic outflow to BAT, in response to cold and high-fat diet, but also by the increase or decrease of the sympathetic outflow to selected WAT depots, in response to different lipolytic requirements of these two conditions. More recently, a role has been attributed to the parasympathetic nervous system (PNS) in modulating both adipose tissue insulin-mediated glucose uptake and fatty free acid (FFA) metabolism in an anabolic way and its endocrine function. The regulation of adipose tissue is unlikely to be limited to the autonomic control, since a number of signaling cytokines and neuropeptides play an important role, as well. In this review, we report some experimental evidences about the role played by both the ANS and orexins into different fat pads, related to food intake and energy expenditure, with a special emphasis on body weight status and fat mass (FM) content.

Neuroleptic malignant syndrome: an easily overlooked neurologic emergency

Neuroleptic malignant syndrome is an unpredictable iatrogenic neurologic emergency condition, mainly arising as an idiosyncratic reaction to antipsychotic agent use. It is characterized by distinctive clinical features including a change in mental status, generalized rigidity, hyperpyrexia, and dysautonomia. It can be lethal if not diagnosed and treated properly. Mortality and morbidity attributed to this syndrome have recently declined markedly due to greater awareness, earlier diagnosis, and intensive care intervention. In most cases, the syndrome occurs as a result of a rapid increase in a dose of neuroleptic, especially one of the long-acting ones. Pathophysiology behind this syndrome is attributed to a dopamine receptor blockade inside the neurons rendered by the offending drug and excessive calcium release from the sarcoplasmic reticulum of skeletal myocytes. Laboratory tests, although not diagnostic, may assist in assessing the severity of the syndrome and also the consequent complications. The syndrome has been described in all age groups and occurs more in males than in females. Genetics appears to be central regarding the etiology of the syndrome. Stopping the use of the offending agent, cold intravenous fluids, and removal of the causative agent and its possible active metabolites is the cornerstone of treatment. Periodic observation of psychotic patients recently started on antipsychotic medications, especially those being treated with depot preparations, may aid to an early diagnosis of the syndrome and lead to early treatment.

Effects of low-carbohydrate diet therapy in overweight subjects with autoimmune thyroiditis: possible synergism with ChREBP

The thyroid is one of the metabolism regulating glands. Its function is to determine the amount of calories that the body has to burn to maintain normal weight. Thyroiditides are inflammatory processes that mainly result in autoimmune diseases. We have conducted the present study in order to have a clear picture of both autoimmune status and the control of body weight. We have evaluated the amount of either thyroid hormones, or antithyroid, or anti-microsomal, or anti-peroxidase antibodies (Abs) in patients with high amounts of Abs. In a diet devoid of carbohydrates (bread, pasta, fruit, and rice), free from goitrogenic food, and based on body mass index, the distribution of body mass and intracellular and extracellular water conducted for 3 weeks gives the following results: patients treated as above showed a significant reduction of antithyroid (−40%, P<0.013), anti-microsomal (−57%, P<0.003), and anti-peroxidase (−44%, P<0,029) Abs. Untreated patients had a significant increase in antithyroid (+9%, P<0.017) and anti-microsomal (+30%, P<0.028) Abs. Even the level of anti-peroxidase Abs increased without reaching statistical significance (+16%, P>0064). With regard to the body parameters measured in patients who followed this diet, reduction in body weight (−5%, P<0.000) and body mass index (−4%, P<0.000) were observed. Since 83% of patients with high levels of autoantibodies are breath test positive to lactase with a lactase deficit higher than 50%, this fact led us to hypothesize a correlation with carbohydrate-responsive element-binding protein and therefore a possible role of carbohydrate metabolism in the development and maintenance of autoimmune thyroiditis associated with body weight increase and slower basic metabolism.

Role of the Orexin System on the Hypothalamus-Pituitary-Thyroid Axis

Hypocretin/orexin (ORX) are two hypothalamic neuropeptides discovered in 1998. Since their discovery, they have been one of the most studied neuropeptide systems because of their projecting fields innervating various brain areas. The orexinergic system is tied to sleep-wakefulness cycle, and narcolepsy is a consequence of their system hypofunction. Orexinergic system is also involved in many other autonomic functions such as feeding, thermoregulation, cardiovascular and neuroendocrine regulation. The main aim of this mini review article is to investigate the relationship between ORX and thyroid system regulation. Although knowledge about the ORX system is evolving, its putative effects on hypothalamic-pituitary-thyroid (HPT) axis still appear unclear. We analyzed some studies about ORX control of HPT axis to know better the relationship between them. The studies that were analyzed suggest Hypocretin/ORX to modulate the thyroid regulation, but the nature (excitatory or inhibitory) of this possible interaction remains actually unclear and needs to be confirmed.

Parachute Jumping Induces More Sympathetic Activation Than Cortisol Secretion in First-Time Parachutists

Background:

The word “stress” describes the status of the body affected by external or internal forces, or “stressors”, threatening to alter its dynamic balance or homeostasis. The adaptive changes which occur in reply to stressors are either behavioral or physical. Once a given threshold is surpassed, a systemic reaction takes place involving the “stress system” in the brain together with its peripheral components, the hypothalamic-pituitary-adrenal axis and autonomic sympathetic.

Objectives:

Stress induces an activation of the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. The purpose of this study was to investigate whether the SNS and the HPA axis would show parallel or divergent stress response patterns in a session of first parachute jump.

Patients and Methods:

Activation of the SNS was evaluated by dosage of salivary alpha-amylase, galvanic skin responses, and heart rate in seven male novice parachutists. Activation of HPA axis was tested by dosage of cortisol. These variables were measured before and 1 minute and 90 minute after the jump.

Results:

All variables reached a peak at 1 minute post-jump. Salivary alpha-amylase, galvanic skin responses and heart rate did not return to basal value at 90 minutes post-jump, while cortisol returned to basal value at 90 minutes post-jump.

Conclusions:

This evidence indicates that parachute jumping is accompanied by a dissociation of SNS and HPA response patterns in novice parachutists, showing a slower recovery in sympathetic activity than in cortisol secretion.

Orexin-A controls sympathetic activity and eating behavior

It is extremely important for the health to understand the regulatory mechanisms of energy expenditure. These regulatory mechanisms play a central role in the pathogenesis of body weight alteration. The hypothalamus integrates nutritional information derived from all peripheral organs. This region of the brain controls hormonal secretions and neural pathways of the brainstem. Orexin-A is a hypothalamic neuropeptide involved in the regulation of feeding behavior, sleep-wakefulness rhythm, and neuroendocrine homeostasis. This neuropeptide is involved in the control of the sympathetic activation, blood pressure, metabolic status, and blood glucose level. This minireview focuses on relationship between the sympathetic nervous system and orexin-A in the control of eating behavior and energy expenditure. The “thermoregulatory hypothesis” of food intake is analyzed, underlining the role played by orexin-A in the control of food intake related to body temperature. Furthermore, the paradoxical eating behavior induced orexin-A is illustrated in this minireview.

The effects of quetiapine on sleep in recovering alcohol-dependent subjects: a pilot study

OBJECTIVE

The aim of this hypothesis-generating pilot study was to assess prospectively the objective and subjective effects of treatment with quetiapine XR on sleep during early recovery from alcohol dependence (AD).

METHODS

Recovering subjects with AD and sleep disturbance complaints were treated with quetiapine XR (n = 10) or matching placebo pills (n = 10) for 8 weeks. Polysomnography was used to assess sleep objectively, and the Insomnia Severity Index and Pittsburgh Sleep Quality Index were used to measure subjective insomnia. Other assessment measures included the 10-minute psychomotor vigilance task (for neurobehavioral functioning), the time-line follow-back measure (for alcohol consumption), the Penn Alcohol Craving Scale (for alcohol craving), the Patient Health Questionnaire-9 item scale (for depressive symptoms), and the Beck Anxiety Inventory (for anxiety symptoms).

RESULTS

Although there was no effect of quetiapine XR on sleep efficiency (time spent asleep/total recording time), there was a pre-to-post reduction in wake after sleep onset time (P = 0.03) and nonsignificant trends for increases in sleep onset latency (SOL) and stage 2 sleep time. A time × drug interaction was seen for the subjective insomnia, such that quetiapine XR-treated subjects reported greater initial improvement in their subjective insomnia, but the difference was not sustained. There were no differences between treatment groups on other measures or medication compliance.

CONCLUSION

Quetiapine XR improves objective sleep continuity and transiently improves subjective insomnia early in recovery from AD.

Hormonal changes in menopause and orexin-a action

Menopause is a period of significant physiological changes that may be associated with increased body weight and obesity-related diseases. Many researches were conducted to assess the contribution of factors such as estrogen depletion, REE decline, and aging to weight gain. An increase in orexin-A plasma levels, paralleling lower estrogen levels, was found during menopause. Orexins are hypothalamic neuropeptides recently discovered, involved in the regulation of feeding behaviour, sleep-wakefulness rhythm, and neuroendocrine homeostasis. Orexins might offer the missing link between postmenopausal hypoestrogenism and other manifestations of the menopausal syndrome, including appetite and weight changes and increase in cardiovascular risk.

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.

Risperidone alters food intake, core body temperature, and locomotor activity in mice

Risperidone induces significant weight gain in female mice; however, the underlying mechanisms related to this effect are unknown. We investigated the effects of risperidone on locomotor activity, core body temperature, and uncoupling protein (UCP) and hypothalamic orexin mRNA expression. Female C57BL/6J mice were acclimated to individual housing and randomly assigned to either risperidone (4 mg/kg BW day) or placebo (PLA). Activity and body temperature were measured over 48-hour periods twice a week for 3 weeks. Food intake and body weights were measured weekly. UCP1 (BAT), UCP3 (gastrocnemius), and orexin (hypothalamus) mRNA expressions were measured using RT-PCR. Risperidone-treated mice consumed more food (p=0.050) and gained more weight (p=0.0001) than PLA-treated mice after 3 weeks. During the initial 2 days of treatment, there was an acute effect of treatment on activity (p=0.046), but not body temperature (p=0.290). During 3 weeks of treatment, average core body temperatures were higher in risperidone-treated mice compared to controls during the light phase (p=0.0001), and tended to be higher during the dark phase (p=0.057). Risperidone-treated mice exhibited lower activity levels than controls during the dark phase (p=0.006); there were no differences in activity during the light phase (p=0.47). UCP1 (p<0.01) and UCP3 (p<0.05) mRNA expressions were greater in risperidone-treated mice compared to controls, whereas, orexin mRNA expression was lower in risperidone-treated mice (p<0.01). These results suggest that risperidone-induced weight gain in mice is a consequence of increased energy intake and reduced activity, while the elevation in body temperature may be a result of thermogenic effect of food intake and elevated UCP1, UCP3, and a reduced hypothalamic orexin expression.

Pharmacological management of atypical antipsychotic-induced weight gain

Excessive bodyweight gain was reported during the 1950s as an adverse effect of typical antipsychotic drug treatment, but the magnitude of bodyweight gain was found to be higher with the atypical antipsychotic drugs that were introduced after 1990. Clozapine and olanzapine produce the greatest bodyweight gain, ziprasidone and aripiprazole have a neutral influence, and quetiapine and risperidone cause an intermediate effect. In the CATIE study, the percentage of patients with bodyweight gain of >7% compared with baseline differed significantly between the antipsychotic drugs, i.e. 30%, 16%, 14%, 12% and 7% for olanzapine, quetiapine, risperidone, perphenazine (a typical antipsychotic) and ziprasidone, respectively (p<0.001). Appetite stimulation is probably a key cause of bodyweight gain, but genetic polymorphisms modify the bodyweight response during treatment with atypical antipsychotics. In addition to nutritional advice, programmed physical activity, cognitive-behavioural training and atypical antipsychotic switching, pharmacological adjunctive treatments have been assessed to counteract excessive bodyweight gain. In some clinical trials, nizatidine, amantadine, reboxetine, topiramate, sibutramine and metformin proved effective in preventing or reversing atypical antipsychotic-induced bodyweight gain; however, the results are inconclusive since few randomized, placebo-controlled clinical trials have been conducted. Indeed, most studies were short-term trials without adequate statistical power and, in the case of metformin, nizatidine and sibutramine, the results are contradictory. The tolerability profile of these agents is adequate. More studies are needed before formal recommendations on the use of these drugs can be made. Meanwhile, clinicians are advised to use any of these adjunctive treatments according to their individual pharmacological and tolerability profiles, and the patient's personal and family history of bodyweight gain and metabolic dysfunction.

Olanzapine blocks the sympathetic and hyperthermic reactions due to cerebral injection of orexin A

Since experiments regarding a possible relation between olanzapine and orexin A has been scarcely reported in international literature, this experiment tested the effect of olanzapine on the sympathetic and thermogenic effects induced by orexin A. The firing rates of the sympathetic nerves to interscapular brown adipose tissue (IBAT), along with IBAT, colonic temperatures and heart rate were monitored in urethane-anesthetized male Sprague-Dawley rats before an injection of orexin A (1.5 nmol) into the lateral cerebral ventricle and over a period of 150 min after the injection. The same variables were monitored in rats with an intraperitoneal administration of olanzapine (10mg/kg bw), injected 30 min before the orexin administration. The results show that orexin A increases the sympathetic firing rate, IBAT, colonic temperatures and heart rate. This increase is blocked by the injection of olanzapine. These findings indicate that olanzapine affects the complex reactions related to activation of orexinergic system.