Effects of the classical antipsychotic haloperidol and atypical antipsychotic risperidone on weight gain, the oestrous cycle and uterine weight in female rats

Haloperidol and aripiprazole impact on the BDNF and glucocorticoid receptor levels in the rat hippocampus and prefrontal cortex: effect of the chronic mild stress

Objective. Changes in the brain derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR) expression in the prefrontal cortex (PFC) and hippocampus (HIP) are associated with psychiatric diseases and stress response. Chronic mild stress (CMS) may alter BDNF as well as GR levels in both the PFC and the HIP. The aim of the present study was to find out whether chronic treatment with a typical antipsychotic haloperidol (HAL) and an atypical antipsychotic aripiprazole (ARI) may modify the CMS effect on the BDNF and GR expression in the above-mentioned structures. Methods. The rats were exposed to CMS for 3 weeks and from the 7^th day of CMS injected with vehicle (VEH), HAL (1 mg/kg) or ARI (10 mg/kg) for 4 weeks. BDNF and GR mRNA levels were established in the PFC and the HIP by Real Time PCR, whereas, PFC and HIP samples were obtained by punching them from 500 µm thick frozen sections. C-Fos immunoreactivity was analyzed in the PFC and the HIP on 30 µm thick paraformaldehyde fixed sections. Weight gain and corticosterone (CORT) levels were also measured. Results. The CMS and HAL suppressed the BDNF and GR mRNA levels in the PFC. In the HIP, CMS elevated BDNF mRNA levels that were suppressed by HAL and ARI treatments. The CMS decreased the c-Fos immunoreactivity in the PFC in both HAL- and ARI-treated animals. In the HIP, HAL increased the c-Fos immunoreactivity that was again diminished in animals exposed to CMS. Stressed animals gained markedly less weight until the 7^th day of CMS, however, later their weight gain did not differ from the unstressed ones or was even higher in CMS+HAL group. Un-stressed HAL and ARI animals gained less weight than the VEH ones. Neither CMS nor HAL/ARI affected the plasma CORT levels. Conclusion. The present data indicate that HAL and ARI in the doses 1 mg/kg or 10 mg/kg, respectively, does not modify the effect of the CMS preconditioning on the BDNF and GR mRNA levels in the PFC or the HIP. However, HAL seems to modify the CMS effect on the HIP activation.

Exercise intervention for preventing risperidone-induced dyslipidemia and gluco-metabolic disorders in female juvenile rats

Risperidone use in children and adolescents is associated with the development of metabolic disorders including increased accumulation of body fat, dyslipidemia, and glucose and insulin metabolism dysregulation. As pharmacological interventions are often limited in their ability to treat a range of side-effects, this study aimed to evaluate the effectiveness of daily voluntary exercise intervention to prevent metabolic side-effects induced by risperidone in juveniles. Thirty-two juvenile female Sprague Dawley rats were treated with risperidone (0.9 mg/kg; b.i.d; n = 16) or vehicle (0.3 g cookie dough pellet; n = 16). These rats were then assigned to a sedentary or voluntary exercise intervention (three hours daily access to running wheels) group (n = 8/group) for a period of four weeks. An intra-peritoneal glucose tolerance test was performed after three weeks of risperidone treatment and exercise intervention to assess glucose tolerance. During the exercise intervention, risperidone-treated rats ran significantly less than vehicle-treated rats. Risperidone treatment of sedentary rats resulted in significantly increased white adipose tissue, fasting triglyceride and fasting insulin compared to vehicle-treated sedentary rats. Exercise intervention of risperidone-treated rats prevented significant increases in these metabolic parameters compared to risperidone-treated sedentary rats. These results support voluntary exercise as an effective mitigator of metabolic side-effects associated with risperidone treatment in juvenile rats. Dyslipidemia and dysregulation of glucose and insulin metabolism are significant risk factors for morbidities and mortality later in life, therefore a focus on strategies to mitigate these adverse effects is critical. Our findings support clinical trials in exercise intervention to prevent metabolic disorders associated with antipsychotic medication in children and adolescents.

Hyperprolactinaemia: A guide for psychiatrists

Medications prescribed by psychiatrists are known to elevate serum prolactin levels, but hyperprolactinaemia remains underrecognised, as the adverse effects of an elevated prolactin are mostly not visible. Hyperprolactinaemia can lead to adverse health outcomes, so clinicians need not only to be alert to its symptoms, but to manage the consequences as well. In this article we provide a brief overview of prolactin physiology, regulation and function. We list various factors that can lead to elevated serum prolactin. We discuss the interpretation of blood results and the management of psychotropic-induced hyperprolactinaemia. We include a flow diagram to assist clinicians in decision-making in the clinical management of hyperprolactinaemia.

Learning Objectives

• Understand prolactin physiology and regulation

• Understand hyperprolactinaemia and its causes

• Know the consequences of hyperprolactinaemia and appropriately manage it in clinical practice

Depot risperidone-induced adverse metabolic alterations in female rats

Atypical antipsychotics are associated with adverse metabolic effects including weight gain, increased adiposity, dyslipidaemia, alterations in glucose metabolism and insulin resistance. Increasing evidence suggests that metabolic dysregulation precedes weight gain development. The aim of this study was to evaluate alterations in adipokines, hormones and basic serum biochemical parameters induced by chronic treatment with depot risperidone at two doses (20 and 40 mg/kg) in female Sprague-Dawley rats. Dose-dependent metabolic alterations induced by risperidone after 6 weeks of treatment were revealed. Concomitant to weight gain and increased liver weight, an adverse lipid profile with an elevated triglyceride level was observed in the high exposure group, administered a 40 mg/kg dose repeatedly, while the low dose exposure group, administered a 20 mg/kg dose, developed weight gain without alterations in the lipid profile and adipokine levels. An initial peak in leptin serum level after the higher dose was observed in the absence of weight gain. This finding may indicate that the metabolic alterations observed in this study are not consequent to body weight gain. Taken together, these data may support the primary effects of atypical antipsychotics on peripheral tissues.

Antipsychotic-induced metabolic effects in the female rat: Direct comparison between long-acting injections of risperidone and olanzapine

Several antipsychotics have well-known adverse metabolic effects. Studies uncovering molecular mechanisms of such drugs in patients are challenging due to high dropout rates, previous use of antipsychotics and restricted availability of biological samples. Rat experiments, where previously unexposed animals are treated with antipsychotics, allow for direct comparison of different drugs, but have been hampered by the short half-life of antipsychotics in rodents. The use of long-acting formulations of antipsychotics could significantly increase the value of rodent models in the molecular characterization of therapeutic and adverse effects of these agents. However, as long-acting formulations have rarely been used in rodents, there is a need to characterize the basic metabolic phenotype of different antipsychotics. Using long-acting olanzapine injections as a positive control, the metabolic effects of intramuscular long-acting risperidone in female rats were investigated for the first time. Like olanzapine, risperidone induced rapid, significant hyperphagia and weight gain, with concomitant increase in several plasma lipid species. Both drugs also induced weight-independent upregulation of several genes encoding enzymes involved in lipogenesis, but this activation was not confirmed at the protein level. Our findings shed light on the role of drug administration, drug dose and nutritional status in the development of rodent models for adverse metabolic effects of antipsychotic agents.

Effects of ovarian dopaminergic receptors on ovulation

Hormonal and neural signals regulate the ovarian follicular development. The present study's hypothesis is that the blockade of ovarian dopamine receptors locally will affect follicle development and ovulation. Groups of adult 4-day cyclic rats of the CII-ZV strain on estrus, diestrus-1, diestrus-2, or proestrus day were injected with vehicle, haloperidol (DA2 > DA1 blocker), sulpiride (DA2 blocker), or SCH-23390 (DA1 blocker) into the bursa of both ovaries at 08:00, 13:00, or 20:00 h. Animals were sacrificed the following predicted estrus day. The following treatments blocked ovulation: injecting haloperidol to rats on estrus or diestrus-1 at 8:00, 13:00, or 20:00 h and to rats on diestrus-2 at 08:00, or 20:00 h; injecting SCH-23390 to rats on diestrus-1 at 8:00, 13:00, or 20:00 h; injecting sulpiride to rats on estrus at 20:00 h, diestrus-1 at 08:00, 13:00, or 20:00 h and to rats on diestrus-2 at 08:00 h. In rats treated with any of the dopamine antagonists that blocked ovulation, injecting GnRH at 14.00 h on the next predicted proestrus day restored ovulation. Injecting estradiol benzoate at 14.00 h of the next predicted diestrus-2 restored ovulation in some animals treated with haloperidol on estrus or diestrus-2 and was ineffective in rats treated on diestrus-1. In rats treated with sulpiride or SCH-23390 ovulation occurred in most animals (SCH-23390: 6/8; SPD: 9/12). Present results suggest that dopamine ovarian receptors' participation in regulating follicular development and ovulation varies along the estrus cycle, with their most prominent activity occurring on diestrus-1.

Repeated aripiprazole treatment causes dopamine D2 receptor up-regulation and dopamine supersensitivity in young rats

Aripiprazole is a second-generation antipsychotic that is increasingly being prescribed to children and adolescents. Despite this trend, little preclinical research has been done on the neural and behavioral actions of aripiprazole during early development. In the present study, young male and female Sprague-Dawley rats were pretreated with vehicle, haloperidol (1 mg/kg), or aripiprazole (10 mg/kg) once daily on postnatal days (PD) 10-20. After 1, 4, or 8 days (i.e. on PD 21, PD 24, or PD 28), amphetamine-induced locomotor activity and stereotypy, as well as dorsal striatal D2 receptor levels, were measured in separate groups of rats. Pretreating young rats with aripiprazole or haloperidol increased D2 binding sites in the dorsal striatum. Consistent with these results, dopamine supersensitivity was apparent when aripiprazole- and haloperidol-pretreated rats were given a test day injection of amphetamine (2 or 4 mg/kg). Increased D2 receptor levels and altered behavioral responding persisted for at least 8 days after conclusion of the pretreatment regimen. Contrary to what has been reported in adults, repeated aripiprazole treatment caused D2 receptor up-regulation and persistent alterations of amphetamine-induced behavior in young rats. These findings are consistent with human clinical studies showing that children and adolescents are more prone than adults to aripiprazole-induced side effects, including extrapyramidal symptoms.

The Effects of Antipsychotics on Prolactin Levels and Women's Menstruation

Introduction. Typical and atypical antipsychotic agent is currently used for treatment in the majority of patients with psychotic disorders. The aim of this review is to assess antipsychotic induced hyperprolactinaemia and the following menstrual dysfunction that affects fertility, quality of life, and therapeutic compliance of women. Method. For this purpose, Medline, PsychInfo, Cochrane library, and Scopus databases were accessed, with a focus on the publication dates between 1954 and 2012. Research of references was also performed and 78 studies were retrieved and used for the needs of this review. Results. A summary of several antipsychotics as well as frequency rates and data on hyperprolactinaemia and menstrual disorders for different agent is presented. Conclusion. Diverse prevalence rates of hyperprolactinaemia and menstrual abnormalities have been found about each medication among different studies. Menstruation plays an important role for women, thus, understanding, careful assessment, and management of hyperprolactinaemia could enhance their lives, especially when dealing with women that suffer from a psychotic disorder.

The effect of ziprasidone on body weight and energy expenditure in female rats

Ziprasidone, a novel antipsychotic agent with a unique receptor-binding profile, has been reported to have lower propensity for weight gain compared with other atypical antipsychotics. Here, we examined the effects of ziprasidone on resting energy expenditure, physical activity, thermogenesis, food intake, and weight gain in female Sprague-Dawley rats. Ziprasidone (20 mg/kg) or vehicle was administered once daily for 7 weeks; and body weight, food intake, resting energy expenditure, locomotor activity, colonic temperature on cold exposure, and abdominal fat were measured. Compared with control animals, ziprasidone-treated rats gained significantly less weight (P = .031), had a lower level of physical activity (P = .016), showed a higher resting energy expenditure (P < .001), and displayed a greater capacity for thermogenesis when subjected to cold (P < .001). In addition, ziprasidone-treated rats had a lower level of abdominal fat than did controls, although the difference was not significant. Ziprasidone had no effect on food intake. Our results indicate that, in female Sprague-Dawley rats, a 7-week treatment regimen of ziprasidone induces a significant decrease in weight gain by increasing resting energy expenditure without decreasing food intake and even with a lower level of physical activity. Further studies are needed to elucidate the precise mechanism of lower propensity of weight gain of ziprasidone.

Reversal of haloperidol-induced orofacial dyskinesia by Murraya koenigii leaves in experimental animals

CONTEXT

Orofacial dyskinesia (OD) is a late complication of prolonged neuroleptic treatment characterized by involuntary movements of the oral region. Chronic treatment with neuroleptics leads to development of vacuous chewing movements (VCMs). VCMs in rats are widely accepted as an animal model of OD.

OBJECTIVE

To study the effect of Murraya koenigii L. (Rutaceae) leaves on haloperidol-induced OD.

MATERIALS AND METHODS

Effect of alcohol extract of M. koenigii leaves (EEMK) and its alkaloid fraction (AMK) on body weight, locomotor activity, behavioral parameters, such as VCMs, tongue protrusions (TPs), orofacial bursts (OBs), and biochemical parameters such as antioxidant defense enzymes levels [superoxide dismutase (SOD) and catalase (CAT)], glutathione (GSH) levels, and lipid peroxidation (LPO) in the forebrain region was studied in haloperidol-treated rats.

RESULTS

Rats chronically treated with haloperidol (1 mg/kg, i.p., 21 days) significantly decreased locomotion and developed VCMs, OBs, and TPs. Biochemical analysis reveals that chronic haloperidol-treated rats also showed decreased levels of SOD and CAT. Chronic haloperidol treatment significantly induced LPO and decreased the forebrain GSH levels in the rats. Co-administration of EEMK (100 and 300 mg/kg, p.o.) and AMK (30 and 100 mg/kg, p.o.) along with haloperidol significantly reversed the effect on locomotion. EEMK and AMK significantly reversed the haloperidol-induced decrease in forebrain SOD and CAT levels in rats and significantly reduced the LPO and restored the decreased GSH levels by chronic haloperidol treatment.

CONCLUSION

The study concludes that M. koenigii could be screened as a potential drug for the prevention or treatment of neuroleptic-induced OD.

Metabolic consequences of antipsychotic therapy: preclinical and clinical perspectives on diabetes, diabetic ketoacidosis, and obesity

Antipsychotic drugs, particularly second-generation antipsychotics (SGAs), have reduced the burden to society of schizophrenia, but many still produce excessive weight gain. A significant number of SGAs also act directly to impair glycemic control causing insulin resistance, impaired glucose tolerance and type 2 diabetes, and also rarely diabetic ketoacidosis (DKA). Schizophrenia itself is almost certainly causal in many endocrine and metabolic disturbances, making this population especially vulnerable to the adverse metabolic consequences of treatment with SGAs. Hence, there is an urgent need for a new generation of antipsychotic drugs that provide efficacy equal to the best of the SGAs without their liability to cause weight gain or type 2 diabetes. In the absence of such safe and effective alternatives to the SGAs, there is a substantial clinical need for the introduction of new antipsychotics without adverse metabolic effects and new antiobesity drugs to combat these metabolic side effects. We discuss the adverse metabolic consequences of schizophrenia, its exacerbation by a lack of social care, and the additional burden placed on patients by their medication. A critical evaluation of the animal models of antipsychotic-induced metabolic disturbances is provided with observations on their strengths and limitations. Finally, we discuss novel antipsychotic drugs with a lower propensity to increase metabolic risk and adjunctive medications to mitigate the adverse metabolic actions of the current generation of antipsychotics.

Intermittent treatment with olanzapine causes sensitization of the metabolic side-effects in rats

The second generation antipsychotic drugs are effective treatments for psychotic disorders. Many of these compounds, including the drug olanzapine, have been associated with metabolic side-effects, including weight gain, impaired glucose tolerance and insulin resistance, which increase the risk of developing cardiometabolic disorders. Rodent models of olanzapine-induced metabolic side-effects have been used to study the physiology of these effects, but only at a single time point after drug treatment. The purpose of the present study was to examine longitudinal changes with chronic antipsychotic drug treatment. Adult female rats were treated with either olanzapine (15 mg/kg) or vehicle for five consecutive days each week, followed by a 48 h washout period. Animals were then challenged with either olanzapine (15 mg/kg) or vehicle, and fasting glucose and insulin values were recorded, as well as glucose clearance in the glucose tolerance test. Treatment with olanzapine was continued for 10 weeks, with weekly tests of metabolic indices. Rats treated acutely with olanzapine showed both glucose dysregulation and insulin resistance; for the group treated during the week with olanzapine, these effects did not change by the end of ten weeks of treatment. However, in the group of animals challenged only once per week with olanzapine, the metabolic side-effects markedly intensified with the passage of time, whereby glucose intolerance and insulin resistance increased significantly compared to both baseline values and all other treatment groups. This previously unreported sensitization phenomenon represents a novel finding that may have clinical implications for patients receiving intermittent antipsychotic drug dosing or with variable adherence to treatment.

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.

The antipsychotics haloperidol and chlorpromazine increase bone metabolism and induce osteopenia in female rats

The main objective of this study was to evaluate the effects of the antipsychotic drugs haloperidol (HAL) and chlorpromazine (CPZ) on bone mineral density (BMD) in female rats and to examine the relationship between the effects on bone and reproductive organs or hormone concentrations. Female rats were orally administered HAL (2 or 10 mg/kg) or CPZ (25 or 50 mg/kg) once daily (7 days/week) for 6 months resulting in a significant increase in prolactin. Hyperprolactinemia resulted in enlarged corpora lutea in the ovary, because prolactin has a luteotropic activity. Thus, atrophy in the uterus, epithelial mucification in the vagina and continuous diestrus stages were observed. These events in the reproductive organs induced a decrease in estradiol, elevation of biochemical markers of bone metabolism, significant reductions of BMD in trabecular bone of the femur and decreased trabecular bone in the femur. The bone loss is associated with an increase in bone resorption due to decreased estradiol derived from the luteotropic activity of prolactin. The mechanism of dopamine blockers to induce bone loss in female rats is considered to be rodent specific because the luteotropic effects of prolactin are confined primarily to rodents. Also, it appears that chronic hyperprolactinemia and maintained corpora lutea leading to bone loss are commonly inducible in female rats receiving long-term treatment with antipsychotic drugs possessing dopamine D2 receptor antagonist activity.

Lactational exposure to atypical antipsychotic drugs disrupts the pituitary-testicular axis in mice neonates during post-natal development

Olanzapine (OLNZ) and risperidone (RISP), two widely prescribed drugs for post-partum psychosis, transfer through milk to the neonates. Hence, neonates are susceptible to their adverse side effects. In the present study, the pituitary-testicular axis of lactationally exposed mice neonates (PND 28) was examined to evaluate the reproductive adverse effects. Testicular histopathology, immunocytochemistry and morphometric analysis of pituitary PRL (prolactin) and LH (luteinizing hormone) cells and plasma hormonal (PRL, LH and testosterone) levels were the various end points studied. Significantly regressed testes, reduced seminiferous tubules with disrupted germ-cell alignment, spermatogonial exfoliation into the tubule lumens and sparse sperms in the lumens were observed. PRL-immunointensity and plasma levels were elevated, whereas immunoreactivity and plasma levels of LH were decreased. Plasma testosterone levels were also decreased. The hypogonadism thus observed might be mediated by drug-induced hyperprolactinemia, which further inhibited secretions of LH and testosterone. Age may be the factor which made the neonates vulnerable to the PRL elevation by OLNZ which otherwise causes transient elevation in adults and is considered safe. The adverse impact was persistent until adulthood with higher doses of both of the drugs as evident by the analysis of testicular weight, histology and hormonal profiles of post-pubertal mice (PND 63) lactationally exposed as neonates.

Effect of lactational exposure of olanzapine on body weight of mice: a comparative study on neonates of both the sexes during post-natal development

Adverse impact of atypical antipsychotic drugs on body weight of adult and juvenile groups has been well-documented both at clinical and preclinical investigations. However, studies on impact of drug on body weight during fetal or neonatal development received little attention. The present study is the first-ever preclinical investigation demonstrating the effect of lactational exposure of olanzapine (4, 8, and 10 mg/kg) and risperidone (1 and 2 mg/kg), two widely prescribed antipsychotics, on body weight of mice neonates. Body weight gain was observed with both the drugs, although a sex-related differential response was noted. In olanzapine-exposed female neonates, the weight gain was more with the highest dose. Male neonates showed a reverse trend, i.e. the highest gain with the lowest dose. Female neonates exposed to risperidone also showed significant, but less gain as compared to their olanzapine-exposed counterparts. Risperidone-exposed male neonates showed little body weight gain. Waist-to-hip ratio and plasma prolactin level were measured to explain the reason behind the body weight gain, but there were deviations with respect to drug and sex. The body weight gain may be the overall manifestations of drug-induced endocrine and metabolic dysregulations.

Effects of atypical antipsychotic drugs on body weight and food intake in dopamine D2 receptor knockout mice

Many atypical antipsychotic drugs cause weight gain, but the mechanism of this weight gain is unclear. To dissect the role of the dopamine D2 receptor (D2R), an important receptor in the pharmacology of antipsychotic drugs, we analyzed the effect of olanzapine, risperidone, and ziprasidone on changes in body weight and food intake in male wild-type (WT) and D2R knockout (D2R(-/-)) mice. The oral delivery of atypical antipsychotics, olanzapine (5 and 10mg/kg), risperidone (0.1 and 1.0mg/kg) and ziprasidone (10 and 20mg/kg) in both strains mice for 2 weeks suppressed body weight gain, except for olanzapine treatment in D2R(-/-) mice. Olanzapine treatment suppressed body weight gain and decreased food intake in WT mice, but also reduced fat body mass and locomotor activity, whereas D2R(-/-) mice did not show these changes. Ziprasidone and risperidone treatment produced similar responses in WT and D2R(-/-) mice. These data suggest the involvement of D2R in the effect of olanzapine on metabolic regulation. Further studies are required to explore the implications of D2R activity in antipsychotic-mediated metabolic complications.

Olanzapine-induced weight gain in the rat: role of 5-HT2C and histamine H1 receptors

INTRODUCTION

Substantial increases in body weight can be induced by several antipsychotic drugs, most notably olanzapine and clozapine. Antagonism at certain receptors, particularly 5-HT2C and histamine H1 receptors, is implicated in this effect.

MATERIALS AND METHODS

We have investigated the contribution of effects at these receptors to olanzapine-induced weight gain occurring over 5 days following daily intraperitoneal drug injections in groups of eight female rats.

RESULTS

Olanzapine (2 mg/kg) and the 5-HT2C antagonist SB 243213 (1 mg/kg), but not the histamine H1 antagonist mepyramine (1 mg/kg), produced significant increases in percentage body weight above vehicle; olanzapine showed a significantly greater effect than SB 243213. Haloperidol (0.1 mg/kg) alone or with mepyramine had no significant effects on weight gain, while with SB 243213 and with both SB 243213 and mepyramine, it showed olanzapine-like increases in weight.

CONCLUSION

These results suggest that 5-HT2C receptor antagonism or inverse agonism, in the presence of D2 receptor antagonism, may contribute to olanzapine-induced weight gain.

Fluctuation of latent inhibition along the estrous cycle in the rat: modeling the cyclicity of symptoms in schizophrenic women?

Latent inhibition (LI) is a cross-species selective attention phenomenon manifested as poorer conditioning of stimuli that had been experienced as irrelevant prior to conditioning. Disruption of LI by pro-psychotic agents such as amphetamine and its restoration by antipsychotic drugs (APDs) is a well-established model of psychotic symptoms of schizophrenia. There is evidence that in schizophrenic women symptom severity and treatment response fluctuate along the menstrual cycle. Here we tested whether hormonal fluctuation along the estrous cycle in female rats (as determined indirectly via the cellular composition of the vaginal smears) would modulate the expression of LI and its response to APDs. The results showed that LI was seen if rats were in estrus during pre-exposure stage and in metestrus during the conditioning stage of the LI procedure (estrus-metestrus) but not along the remaining sequential phases of the cycle (metestrus-diestrus, diestrus-proestrus and proestrus-estrus). Additionally, the efficacy of typical and atypical APDs, haloperidol and clozapine, respectively, in restoring LI depended on estrous condition. Only LI disruption in proestrus-estrus exhibited sensitivity to both APDs, whereas LI disruption in the other two phases was alleviated by clozapine but not haloperidol. Our results show for the first time that both the expression of LI and its sensitivity to APDs are modulated along the estrous cycle, consistent with fluctuations in psychotic symptoms and response to APDs seen along women's menstrual cycle. Importantly, the results indicate that although both low and high levels of hormones may give rise to psychotic-like behavior as manifested in LI loss, the pro-psychotic state associated with low hormonal level is more severe due to reduced sensitivity to typical APDs. The latter constellation may mimic states of increased vulnerability to psychosis coupled with reduced treatment response documented in schizophrenic women during periods associated with low levels of hormones.

The once-daily human GLP-1 analog, liraglutide, reduces olanzapine-induced weight gain and glucose intolerance

Therapeutic use of atypical antipsychotic agents is often associated with weight gain and impaired glucose tolerance. The once-daily human GLP-1 analog liraglutide improves glycemic control and reduces body weight. We have investigated the ability of liraglutide to improve olanzapine-induced metabolic effects in female rats. Female Sprague-Dawley rats were implanted with subcutaneous osmotic mini pumps for delivery of olanzapine (1.75 mg/24 h) or vehicle for 28 days (n=20). After 14 days, ten animals from each group were given liraglutide (0.2 mg/kg) or vehicle twice daily for the remainder of the study. Compared to vehicle treated animals, olanzapine infusion for 4 weeks significantly increased end point cumulated food intake (667.3+/-7.0 versus 593.2+/-13.2g, p<0.01), body weight (306.6+/-4.2 versus 276.4+/-3.6 g, p<0.001), subcutaneous inguinal fat (3.4+/-0.3 versus 1.9+/-0.1 g, p<0.001), mesenteric fat (3.1+/-0.2 versus 1.7+/-0.2g, p<0.001), retroperitoneal fat (6.2+/-0.6 versus 2.8+/-0.3 g, p<0.001), and impaired glucose tolerance, measured as total area under the glucose curve during an oral glucose tolerance test (1906+/-66 versus 1770+/-28 mMxmin, p<0.05). These olanzapine-induced elevations were significantly reduced by liraglutide (cumulated food intake: 601.8+/-20.4 g, p<0.01; body weight: 280.2+/-5.6 g, p<0.001; subcutaneous inguinal fat: 2.4+/-0.2 g, p<0.001; mesenteric fat: 1.8+/-0.1 g, p<0.001; retroperitoneal fat: 3.5+/-0.4 g, p<0.001; AUC: 1764+/-32 mMxmin, p<0.05). In conclusion, subcutaneous olanzapine infusion in female rats leads to weight gain and metabolic changes of which several are reversed following liraglutide treatment. It may therefore be relevant to study these effects of liraglutide in patients treated with atypically antipsychotics.

Ziprasidone and aripiprazole attenuate olanzapine-induced hyperphagia in rats

Weight gain induced by some second-generation anti-psychotics such as olanzapine has emerged as a most debilitating side-effect. This study investigates whether co-administration with either ziprasidone or aripiprazole, which have little propensity to induce weight gain, can attenuate the hyperphagic effect of olanzapine. Female hooded-Lister rats (n=8 per group) were treated acutely with either vehicle, olanzapine (1 mg/kg), ziprasidone (1 mg/kg), aripiprazole (2 mg/kg) or olanzapine in combination with ziprasidone or aripiprazole and placed in automated locomotor activity (LMA) boxes with preweighed palatable mash. Food intake and LMA were measured for 60 min postdrug treatment. All olanzapine-treated groups demonstrated significant increases in food intake (P<0.001). This effect was attenuated following co-administration of olanzapine with either ziprasidone or aripiprazole (P<0.001), neither of which affected food intake alone. The lack of hyperphagia induced by aripiprazole and ziprasidone may reflect an inherent pharmacological mechanism preventing weight gain.

Investigation into the influence of a high fat diet on antipsychotic-induced weight gain in female rats

Atypical antipsychotic drug therapy may result in substantial weight gain, increased adiposity and the promotion of metabolic abnormalities. The mechanism(s) which underlie such effects remain unclear. Previous studies in our laboratory have demonstrated significant weight gain in female rats maintained on a standard laboratory diet after sub-chronic administration of olanzapine and risperidone, but not ziprasidone. The aim of this paper is to investigate the effect of antipsychotic drugs on body weight, ingestive behaviour and adiposity in female rats with access to a high fat diet. Adult female rats given free access to a high fat diet received either olanzapine (2 mg/kg), risperidone (0.5 mg/kg), ziprasidone (2.5 mg/kg) or vehicle for 28 days. Body weight, food and water intake in addition to intra-abdominal fat deposition were assessed. Olanzapine initially increased body weight but by the end of the study olanzapine animals appeared to have lost weight compared to the vehicle-treated group. Olanzapine-induced reductions in body weight were accompanied by a significant hypophagia during weeks 3 and 4. Risperidone increased body weight during week 1 only and reduced intake of a high fat diet during weeks 3 and 4. Ziprasidone was without effect on indices of body weight and ingestive behaviour. There were no effects of antipsychotic drugs on intra-abdominal fat deposition. Access to a diet high in fat attenuated weight gain induced by olanzapine and risperidone in female rats.

The distinct effects of subchronic antipsychotic drug treatment on macronutrient selection, body weight, adiposity, and metabolism in female rats

INTRODUCTION

Treatment with some antipsychotic drugs may result in excessive body weight gain which can have detrimental effects on patient compliance, morbidity and mortality. The aim of the present study was to investigate the effect of atypical antipsychotic drugs on dietary macronutrient selection, body weight, body composition and biochemical parameters related to obesity in female rats.

MATERIALS AND METHODS

Forty pair-housed, adult female hooded-Lister rats (250 +/- 5 g) were habituated to three diets containing principally protein, fat, or carbohydrate in a home cage self-selection paradigm. Olanzapine (2 mg/kg), risperidone (0.5 mg/kg), ziprasidone (2.5 mg/kg), or vehicle was injected intraperitoneally once daily for 22 days; food selection, water intake, and body weight were recorded daily, while body composition and plasma hormones (insulin, glucose, nonesterified free fatty acid, total cholesterol, glycerol, triacylglycerol, leptin, and prolactin) were analyzed at the end of the study.

RESULTS

Only olanzapine significantly increased body weight and food intake. Macronutrient selection was significantly altered after olanzapine and risperidone treatment (increased protein and decreased fat preference). Only olanzapine increased carcass fat content. Locomotor activity was significantly reduced in all treatment groups. Both olanzapine and risperidone significantly increased plasma prolactin. Olanzapine was without effect on any other biochemical parameter measured. Ziprasidone significantly reduced plasma leptin and nonsignificantly reduced NEFA, while risperidone significantly reduced fasting plasma glucose.

CONCLUSION

This study supports our previous work demonstrating weight gain and increased feeding behavior induced by olanzapine and could have important implications for enhancing our understanding of the mechanisms by which olanzapine and other atypical antipsychotics induce weight gain in the clinic.

A model for antipsychotic-induced obesity in the male rat

INTRODUCTION

Weight gain is a common and severe side effect of antipsychotic drugs. A usual tool to study the side effects of psychotropic drugs is animal models. However, attempts to create an animal model of antipsychotic-induced weight gain were not successful so far. Female rodents are sensitive to the effects of antipsychotics, but not males. This does not match the human clinical situation. Antipsychotics have different pharmacokinetic properties in rats and humans, and rats and humans have different spontaneous diets.

MATERIALS AND METHODS

In the present study, we tested the hypothesis that the insensitivity of male rats to the weight-promoting effects of antipsychotics could be related to the mode of administration of antipsychotics and to the animals' diet. Antipsychotics were mixed with the food, and rats were fed a diet resembling the human diet. Rats were treated with 0.01, 0.1, 0.5, and 2 mg/kg of olanzapine or with a control solution for 6 weeks. Their weight and food intake were recorded, and their body composition were analyzed. The effects on weight and food intake of olanzapine (1 mg/kg), haloperidol (1 mg/kg), and ziprasidone (10 mg/kg) were also compared in a 3-week treatment experiment.

RESULTS

The results showed that 0.5 and 2 mg of olanzapine, but not lower doses, increase body weight and subcutaneous fat deposition. After the 3-week treatment, olanzapine-treated rats, but not haloperidol- or ziprasidone-treated rats, had significantly increased their weight.

CONCLUSION

This study shows that a rat model of obesity induced by antipsychotics can be created under specific conditions of drug administration, diet, and dose.

Distinct endocrine effects of chronic haloperidol or risperidone administration in male rats

Antipsychotic drugs have been used effectively for the treatment of schizophrenia symptoms, but they are often associated with metabolic side effects such as weight gain and endocrine disruptions. To investigate the possible mechanisms of antipsychotic-induced metabolic effects, we studied the impact of chronic administration of a typical antipsychotic drug (haloperidol) and an atypical antipsychotic (risperidone) to male rats on food intake, body weight, adiposity, and the circulating concentrations of hormones and metabolites that can influence energy homeostasis. Chronic (28days) haloperidol administration had no effect on food intake, weight gain or adiposity in male rats, whereas risperidone treatment resulted in a transient reduction in food intake and significantly reduced body weight gain compared to vehicle-treated control rats. Whereas neither antipsychotic had any effect on serum lipid profiles, glucose tolerance or the circulating concentrations of hormones controlled by the hypothalamo-pituitary-thyroid (free T4), -adrenal (corticosterone), -somatotropic (IGF-1), or -gonadotropic axes (testosterone), haloperidol increased circulating insulin levels and risperidone increased serum glucagon levels. This finding suggests that haloperidol or risperidone induce distinct metabolic effects. Since metabolic disorders such as obesity and type 2 diabetes mellitus represent serious health issues, understanding antipsychotic-induced endocrine and metabolic effects may ultimately allow better control of these side effects.

Long term treatment with olanzapine mixed with the food in male rats induces body fat deposition with no increase in body weight and no thermogenic alteration

Body weight gain is a worrying side effect of many new antipsychotic drugs. The mechanisms by which antipsychotic drugs increase weight in humans are not known. Attempts to model the metabolic effects of antipsychotic drugs in the animal have not been successful. Female rats appear to be sensitive to the effects of antipsychotics, but male rats less, and this does not match the clinical situation in humans. In previous rodent studies, antipsychotics were always given by daily gavage or injections. Antipsychotics have different pharmacokinetics in rodents and humans, and in the present study, we tested the hypothesis that the insensitivity of male rats to the effects of antipsychotics could be related to their mode of administration. Thus, we administered antipsychotic drugs mixed with the food. Animals were treated during 6 weeks with haloperidol (1mg/kg), olanzapine (1mg/kg), ziprasidone (10mg/kg), or a control solution. Animals were allowed to self-select food among three macronutrients (carbohydrates, lipids and proteins). Food selection was measured throughout the study. At the end of the study, body composition was measured by dissection and weighing of the rat's main organs and tissues. Mitochondrial thermogenesis was measured in brown adipose tissue in olanzapine-treated animals. Circulating leptin, insulin, glucose, triglycerides, cholesterol, high-density lipoprotein (HDL) were also assayed at the end of the study. The results show that none of the antipsychotic treatments modified caloric intake, food selection or body weight. Olanzapine did not alter mitochondrial thermogenesis. However, haloperidol and olanzapine induced a significant increase in adiposity and circulating leptin. Ziprasidone produced a moderate fat accumulation. It is concluded that mixing antipsychotic treatments with the food provides a reliable animal model of antipsychotic-induced fat accumulation.

Chronic nicotine interactions with clozapine and risperidone and attentional function in rats

Although antipsychotic drugs are therapeutically effective in attenuating the hallmark symptoms of schizophrenia, these improvements do not return most patients to normative standards of cognitive function. Thus, complementary drug treatment may be needed to treat the attentional deficits of schizophrenia as well as to counteract the potential attentional impairments caused by some antipsychotic drugs. Nicotine, a drug commonly self-administered by a great majority of individuals with schizophrenia, has been shown to significantly improve cognitive function in some studies. The current study was conducted to determine the interactive effects of the atypical antipsychotic drugs clozapine and risperidone with chronic nicotine administration on attentional performance. Adult female Sprague-Dawley rats (N=35) were trained to perform an attentional task using an operant visual signal detection task. After training, rats were infused with a dose of 5 mg/kg/day (s.c.) nicotine base (n=18) or saline (n=17) for 28 consecutive days via osmotic pump. In Exp. 1, while being administered chronic nicotine or saline, rats were given acute doses of clozapine (0, 0.625, 1.25 and 2.5 mg/kg, s.c.) and were tested for attentional function. In Exp. 2, while on chronic nicotine or saline, other rats were challenged with acute doses of risperidone (0, 0.025, 0.05 and 0.1 mg/kg, s.c.) and were tested for attentional function. Results showed that acute administration of clozapine caused a significant dose-dependent impairment in choice accuracy (percent hit) in animals treated with chronic saline. Chronic nicotine treatment itself lowered accuracy, but attenuated further declines with acute clozapine treatment. Acute administration of risperidone at high dose significantly reduced performance (percent correct rejection) in chronically saline-treated rats, but in a similar fashion as in Exp. 1, chronic nicotine lowered accuracy but attenuated further impairment with acute risperidone. In summary, atypical antipsychotic drugs clozapine and risperidone significantly impaired choice accuracy in the visual signal detection task. Clozapine was more detrimental than risperidone but the adverse effects of both clozapine and risperidone on attentional performance were masked in rats chronically treated with nicotine.

Effects of sub-chronic antipsychotic drug treatment on body weight and reproductive function in juvenile female rats

RATIONALE

Weight gain caused by some antipsychotics is not only confined to adults but can also adversely affect both children and adolescents. Indeed, olanzapine and risperidone have been associated with extreme weight gain in adolescents even greater than that reported in adults. We have recently shown substantial weight gain in adult female rats following treatment with olanzapine and risperidone but not ziprasidone.

OBJECTIVES

The aim of the present study was to compare the effects of several antipsychotics on weight gain and reproductive function in juvenile (aged 7 weeks) female hooded Lister rats.

METHODS

Olanzapine (4 mg/kg), risperidone (0.5 mg/kg), ziprasidone (2.5 mg/kg), sulpiride (10 mg/kg), haloperidol (0.5 mg/kg) or vehicle was administered i.p. once per day for 21 days. Body weight, food and water intake were measured daily, in addition to the determination of stage of the oestrous cycle.

RESULTS

Sub-chronic administration of olanzapine, risperidone, sulpiride and haloperidol, but not ziprasidone, significantly increased body weight compared to vehicle-treated animals during weeks 1-3. Sulpiride significantly increased food and water intake. Significantly increased percentage intra-abdominal fat weight was observed in olanzapine, risperidone, sulpiride and haloperidol, but not ziprasidone-treated animals. Marked disruption of the oestrous cycle was observed in all but the ziprasidone-treated group, which continued to have regular 4-day oestrous cycles.

CONCLUSIONS

Weight gain observed in these juvenile animals was 1.5-2 times greater than that previously observed in adult rats. These findings have important implications for the use of antipsychotics in children and adolescent patients.

Characterisation of olanzapine-induced weight gain and effect of aripiprazole vs olanzapine on body weight and prolactin secretion in female rats

RATIONALE

Atypical antipsychotic drug (APD)-induced weight gain causes non-compliance, increasing the risk of relapse and medical complications.

OBJECTIVES

In an animal model, we assessed body weights, food intake, body fat/lean body mass contents and blood serum levels of glucose and lipids in female rats treated with olanzapine (Experiment 1). Also, we investigated the effect of aripiprazole vs olanzapine treatment on weight gain (WG) and plasma prolactin secretion in two strains (Wistar and Sprague-Dawley) and in two housing conditions (singly and group housed; Experiment 2).

METHODS

In Experiment 1, Wistar females received either vehicle or olanzapine (5.0 mg kg(-1), p.o.) twice daily for 14 days. In Experiment 2, female rats (Wistar or Sprague-Dawley), housed singly or in groups, received either vehicle, aripiprazole (2.0-8.0 mg kg(-1), p.o.), or olanzapine (1.0-10 mg kg(-1), p.o.) twice daily for 7 days. Body weights and food intake were assessed daily. Body composition and blood assays were analyzed at the end of the treatment.

RESULTS

WG induced by chronic olanzapine treatment was characterised by hyperphagia, increased body fat, and serum free fatty acid content and reduced lean tissue and serum glucose content. Subchronic aripiprazole treatment resulted in rapid and robust WG similar to those observed with olanzapine. In spite of similar effects on body weight, aripiprazole and olanzapine stimulated markedly different patterns of prolactin secretion. Body weight changes and prolactin secretion induced by these APDs were significantly modulated by housing and by strain.

CONCLUSION

Assessment of body weight in the present model may not have predictive validity, and other measures may be needed to differentiate between WG-inducing and weight-neutral drugs.

Preclinical Pharmacology of FMPD [6-Fluoro-10-[3-(2-methoxyethyl)-4-methyl-piperazin-1-yl]-2-methyl-4H-3-thia-4,9-diaza-benzo[f]azulene]: A Potential Novel Antipsychotic with Lower Histamine H1 Receptor Affinity Than Olanzapine

FMPD [6-fluoro-10-[3-(2-methoxyethyl)-4-methyl-piperazin-1-yl]-2-methyl-4H-3-thia-4,9-diaza-benzo[f]azulene] is a potential novel antipsychotic with high affinity for dopamine D2 (Ki= 6.3 nM), 5-HT(2A) (Ki= 7.3 nM), and 5-HT6 (Ki= 8.0 nM) human recombinant receptors and lower affinity for histamine H1 (Ki= 30 nM) and 5-HT2C (Ki= 102 nM) human recombinant receptors than olanzapine. Oral administration of FMPD increased rat nucleus accumbens 3,4-dihyroxyphenylacetic acid concentrations (ED200 = 6 mg/kg), blocked 5-HT2A agonist-induced increases in rat serum corticosterone levels (ED50= 1.8 mg/kg), and inhibited the ex vivo binding of [125I]SB-258585 [4-iodo-N-[4-methoxy-3-(4-methyl-piperazin-1-yl)-phenyl]-benzenesulfonamide] to striatal 5-HT6 receptors (ED50= 10 mg/kg) but failed to inhibit ex vivo binding of [3H]pyrilamine to hypothalamic histamine H1 receptors at doses of up to 30 mg/kg. In electrophysiology studies, acute administration of FMPD selectively elevated the number of spontaneously active A10 (versus A9) dopamine neurons and chronic administration selectively decreased the number of spontaneously active A10 (versus A9) dopamine neurons. FMPD did not produce catalepsy at doses lower than 25 mg/kg p.o. In Fos-induction studies, FMPD had an atypical antipsychotic profile in the striatum and nucleus accumbens and increased Fos expression in orexin-containing neurons of the hypothalamus. FMPD produced only a transient elevation of prolactin levels. These data indicate that FMPD is an orally available potent antagonist of dopamine D2, 5-HT2A, and 5-HT6 receptors and a weak antagonist of H1 and 5-HT2C receptors. FMPD has the potential to have efficacy in treating schizophrenia and bipolar mania with a low risk of treatment-emergent extrapyramidal symptoms, prolactin elevation, and weight gain. Clinical trials are needed to test these hypotheses.

A parametric analysis of olanzapine-induced weight gain in female rats

RATIONALE

Some novel antipsychotics, including olanzapine, induce weight gain and metabolic abnormalities, which represent the major adverse effects of these drugs. However, the mechanism(s) involved in such effects are unclear.

OBJECTIVE

The aim of this study was to develop, in female rats, a parametric model of olanzapine-induced weight gain and metabolic abnormalities and evaluate it against clinical findings.

METHODS

Female rats were administered olanzapine b.i.d. at doses of 0, 1, 2 and 4 mg/kg over 20 days, and a wide range of variables were recorded during and after drug administration.

RESULTS

Olanzapine increased both 24 h and total food intake. This was associated with rapid onset weight gain and increased adiposity (assessed by visceral fat pad masses). Insulin, but not glucose, concentrations were elevated, with a significant increase in the HOMA-IR index, indicative of insulin resistance. A nonsignificant trend towards higher levels of leptin was observed. Paradoxically, there was a significant increase in adiponectin. All of these variables showed maximal increases at either 1 or 2 mg/kg and attenuated effects at 4 mg/kg. Prolactin levels were also increased by olanzapine. However, for this variable, there was a clear dose-response curve, with the maximal effect at the highest dose (4 mg/kg).

CONCLUSIONS

These data suggest that aspects of olanzapine-induced weight gain and metabolic abnormalities can possibly be modelled in female rats. It is suggested that olanzapine-induced hyperphagia acts as an initial stimulus which leads to weight gain, enhanced visceral adiposity and subsequent insulin resistance, although the latter may be ameliorated by compensatory responses in adiponectin levels. Prolactin elevation appears likely not to be involved in the weight gain, adiposity and metabolic changes seen in this model.

Investigation into the effects of the novel antipsychotic ziprasidone on weight gain and reproductive function in female rats

Weight gain and sexual dysfunction are serious side effects of certain antipsychotic drugs. Ziprasidone, a novel antipsychotic with a unique receptor binding profile, is reported to have a low propensity for such side effects. Previous results from this laboratory have demonstrated substantial weight gain following sub-chronic treatment with olanzapine and risperidone. Risperidone induced weight gain and markedly impaired reproductive function while olanzapine induced weight gain, without affecting reproductive function. The aim of this study was to investigate effects of ziprasidone on weight gain and reproductive function in female rats. Ziprasidone (1 and 2.5 mg/kg i.p.) or vehicle was administered once daily for 28 days and body weight, food and water intake measured, in addition to histological examination of vaginal lavage to determine the stage of the oestrous cycle. On day 28, the rats were sacrificed and the uterine weights recorded, intra-abdominal fat weight and plasma prolactin levels measured. Ziprasidone failed to induce significant weight gain during weeks 1-3, however, significant weight gain was observed on day 28 at 2.5 mg/kg (p < 0.05). Ziprasidone had no effect on food intake at any time point. A significant reduction in water intake (p < 0.05) was observed during the first week of treatment with 2.5 mg/kg ziprasidone. Ziprasidone had no effect on intra-abdominal fat weight, wet or dry uterine weight or plasma prolactin levels. All ziprasidone treated animals displayed a normal four-day oestrous cycle. This study is the first to report that ziprasidone is without effect on reproductive function or ingestive behaviour in the rat.