Effect of chronic infusion of olanzapine and clozapine on food intake and body weight gain in male and female rats

Many antipsychotics cause weight gain in humans, but usually not in rats, when injected once or twice daily. Since blood antipsychotic half-lives are short in rats, compared to humans, chronic administration by constant infusion may be necessary to see consistent weight gain in rats. Male and female rats were implanted with mini-pumps for constant infusion of olanzapine (5 mg/kg/day), clozapine (10 mg/kg/day) or vehicle for 11 days. Food intake and body weight were measured; blood drug levels were measured by HPLC. Olanzapine increased food intake and body weight in female, but not male rats. Serum olanzapine concentrations were 30-35 ng/ml. Clozapine had no effect on food intake or body weight in female or male rats. Serum clozapine concentrations were about 75 ng/ml. Single-dose pharmacokinetic analysis revealed a serum terminal half-life of 1.2-1.5 h for each drug, with no sex differences. Despite the fact that olanzapine and clozapine promote weight gain in humans, these drugs appear to have minimal effects on body weight and food intake in rats, except for a modest effect of olanzapine in female rats, even though therapeutic levels of olanzapine are achieved in serum during chronic infusion. Hence, the rapid clearance of drug following single administration in previous studies cannot explain the weak or absent effects of antipsychotics on weight gain in this species. The rat thus appears to be an inadequate model of weight gain produced by some antipsychotics in humans.     

The effects of polymorphisms in the DGAT1, leptin and growth hormone receptor gene loci on body energy, blood metabolic and reproductive traits of Holstein cows

The objective of this study was to examine the impact of polymorphisms in the acyl-CoA:diacylglycerol acyltransferase ( DGAT1 ), leptin and growth hormone receptor genes on body energy (body condition score, total body energy content and cumulative effective energy balance) and blood metabolic traits (levels of β-hydroxybutyrate, glucose and non-esterified fatty acids), measured once before the first calving and then repeatedly throughout first lactation in 497 Holstein cows. The influence of the same polymorphisms on cow reproductive performance and health during the first and second lactations was also assessed. Several reproductive traits were considered including interval, conception and insemination traits, as well as incidence of metritis and reproductive problems. Genotyping was performed using PCR-RFLP ( DGAT1 , leptin ) or allele-specific PCR ( growth hormone receptor ). For each locus, the effect of allele substitution on body energy and blood metabolic traits was estimated using random regression models. The same effect on reproductive traits was assessed with single-trait mixed linear models. Significant ( P  <   0.05) effects on specific reproductive traits were observed. DGAT1 and growth hormone receptor alleles responsible for significant increases in milk production were found to have an adverse effect on reproduction, while the leptin allele responsible for significant increase in milk production was linked to marginally increased metritis frequency. Furthermore, the three studied loci were also found to significantly ( P  <   0.05) affect certain body energy and blood metabolic traits. Several associations are published for the first time, but these should be confirmed by other investigators before the polymorphisms are used in gene-assisted selection.     

The obesity in bilateral ovariectomized rats is related to a decrease in the expression of leptin receptors in the brain.

We investigated the expression levels of leptin receptors in the brain of ovariectomized (OVX) rats. The mean expression level of ob mRNA in adipose tissues of OVX rats was significantly (P < 0.01) lower than that in the SHAM operation group rats, and the mean body weight of OVX rats was significantly (P < 0.01) greater than that in the SHAM group rats. However, there were no differences between serum leptin concentrations in these two groups. The mean level of leptin receptor (OB-R) mRNA expression in the brain tissue and the mean level of long form type OB-R (OB-RL) mRNA expression in the hypothalamus of the OVX rats were significantly (P < 0.05) lower than those in the SHAM group rats. These changes were cancelled by supplementation with 17 beta-estradiol in OVX rats. These results suggested that not only changes in the expression level of ob mRNA in adipose tissue and the serum leptin concentration but also changes in the OB-R mRNA in the brain are involved in the body weight increase in OVX rats and that a decrease in OB-R makes transmission of signals to suppress the amount of food intake difficult, thus leading to an increase in body weight.     

The activation of 5-HT receptors in prefrontal cortex enhances dopaminergic activity

Atypical antipsychotics show preferential 5-HT 2A versus dopamine (DA) D2 receptor affinity. At clinical doses, they fully occupy cortical 5-HT2 receptors, which suggests a strong relationship with their therapeutic action. Half of the pyramidal neurones in the medial prefrontal cortex (mPFC) express 5-HT 2A receptors. Also, neurones excited through 5-HT 2A receptors project to the ventral tegmental area (VTA). We therefore hypothesized that prefrontal 5-HT 2A receptors can modulate DA transmission through excitatory mPFC-VTA inputs. In this study we used single unit recordings to examine the responses of DA neurones to local (in the mPFC) and systemic administration of the 5-HT 2A/2C agonist 1-[2,5-dimethoxy-4-iodophenyl-2-aminopropane] (DOI). Likewise, using microdialysis, we examined DA release in the mPFC and VTA (single/dual probe) in response to prefrontal and systemic drug administration. The local (in the mPFC) and systemic administration of DOI increased the firing rate and burst firing of DA neurones and DA release in the VTA and mPFC. The increase in VTA DA release was mimicked by the electrical stimulation of the mPFC. The effects of DOI were reversed by M100907 and ritanserin. These results indicate that the activity of VTA DA neurones is under the excitatory control of 5-HT 2A receptors in the mPFC. These observations may help in the understanding of the therapeutic action of atypical antipsychotics.     

Differential effects of haloperidol and olanzapine on the expression of erythropoietin and its receptor in rat hippocampus and striatum

Compared with first-generation antipsychotics (FGAs), second-generation antipsychotics (SGAs) seem to be neuroprotective and trigger neuroplasticity. Because neuroplasticity is regulated by a variety of neurotrophic factors we studied differential effects of haloperidol (HAL, a FGA) and olanzapine (OLZ, a SGA) on temporal expression of erythropoietin (EPO), a potent neuroprotective factor and its receptor (EPOr) in rat brain. Rats (8-10/group) were treated with HAL or OLZ for 14 days (HAL-14 or OLZ-14) or 45 days (HAL-45 or OLZ-45). Animals were killed by decapitation or by perfusion to collect brains for immunoblotting and immunohistochemical analysis respectively. In hippocampus, the levels of both EPO and EPOr were significantly increased in HAL-14 (p < 0.001) and OLZ-14 (p < 0.001) groups. Their levels decreased in HAL-45 compared with levels in HAL-14 (EPO, p < 0.001; EPOr, p < 0.05), whereas the levels were further increased (EPO, p < 0.05) in OLZ-45 compared with OLZ-14. In striatum, the levels of both EPO and EPOr were unchanged in HAL-14 and EPO levels significantly decreased in HAL-45 (p < 0.05), whereas their levels were significantly increased in OLZ-14 and OLZ-45 compared with the vehicle-treated control (p < 0.001). Both EPO and EPOr were primarily expressed by neurons and endothelial cells. These data suggest that SGAs such as OLZ may have neuroprotective effects through expression of EPO that may be clinically relevant for long-term safe and beneficial management of psychotic patients.     

Voglibose administration regulates body weight and energy intake in high fat-induced obese mice

We tested whether long-term administration of voglibose (VO) prevents diet induced obesity in addition to hypoglycemic effects in high fat fed mice and further investigated the underlying mechanisms by which voglibose exerts its weight lowering effect. Male C57BL/6 mice were fed ad libitum for 12 weeks with the control diet (CTL), high-fat diet (HFD) or the HFD with VO supplementations. Blood lipid profile, plasma leptin levels and hepatic triglyceride content, as well as expressions of genes involved in appetite and mitochondrial function were examined. The results showed that VO significantly reduced body weight, fat mass and energy intakes in high fat fed mice. VO showed improved metabolic profiles including blood glucose, triglyceride and free fatty acid. Elevated levels of plasma leptin in HFD were significantly reduced with the VO, furthermore, VO modulated the hypothalamic expressions of leptin receptors and appetite related genes. VO showed the upregulated expressions of PGC-1 in the liver and epididymal adipose tissue. In conclusion, VO may exert antiobesity properties through reductions in energy intake and improvement in mitochondrial function, indicating that VO has potential therapeutic use in patients with obesity, type 2 diabetes, and related complications.     

Atomistic molecular dynamics simulations of typical and atypical antipsychotic drugs at the dopamine D2 receptor (D2R) elucidates their inhibition mechanism

Dopamine D2 receptor (D2R) plays a pivotal role in nervous systems. Its dysfunction leads to the schizophrenia, Parkinson’s diseases and drug addiction. Since the crystal structure of the D2R was not solved yet, discovering of potent and highly selective anti-psychotic drugs carry challenges for different neurodegenerative diseases. In the current study, we modeled the three-dimensional (3D) structure of the D2R based on a recently crystallized structure of the dopamine D3 receptor. These two receptors share a high amino acid sequence homology (>70%). The interaction of the modeled receptor with well-known atypical and typical anti-psychotic drugs and the inhibition mechanisms of drugs at the catalytic domain were studied via atomistic molecular dynamics simulations. Our results revealed that, class-I and class-II forms of atypical and typical D2R antagonists follow different pathways in the inhibition of the D2Rs.     

Activation of the canonical Wnt pathway by the antipsychotics haloperidol and clozapine involves dishevelled-3

Protein kinase B (Akt), glycogen synthase kinase-3 (GSK-3) and members of the Wnt signal transduction pathway were recently found to be altered in schizophrenia and targeted by antipsychotic drugs. In the current study, selected Wnt signalling proteins were investigated to determine if they are altered by the antipsychotics clozapine or haloperidol in the rat prefrontal cortex. Pheochromocytoma (PC12) and neuroblastoma (SH-SY5Y) cells were also used to elucidate how antipsychotics generated the pattern of changes observed in vivo . Western blotting (WB) revealed that treatment with haloperidol or clozapine caused an up-regulation of Wnt-5a, dishevelled-3, Axin, total and phosphorylated GSK-3 and β-catenin protein levels. Treatment of PC12 and SH-SY5Y cells with a variety of pharmacological agents as well as the over-expression of several Wnt related proteins failed to mimic the pattern observed in vivo following antipsychotic treatment. However, the over-expression of dishevelled-3 nearly perfectly duplicated the changes observed in vivo . Immunoprecipitations (IP) conducted using protein isolated from the rat prefrontal cortex indicated that dishevelled-3 is associated with the D₂ dopamine receptor thereby suggesting that antipsychotics may act on dishevelled-3 via D₂ dopamine receptors to initiate a cascade of downstream changes involving Axin, GSK-3 and β-catenin that may help to alleviate psychosis in schizophrenic patients.     

Variation in genes related to hepatic lipid metabolism and changes in waist circumference and body weight

We analysed single nucleotide polymorphisms (SNPs) tagging the genetic variability of six candidate genes (ATF6, FABP1, LPIN2, LPIN3, MLXIPL and MTTP) involved in the regulation of hepatic lipid metabolism, an important regulatory site of energy balance for associations with body mass index (BMI) and changes in weight and waist circumference. We also investigated effect modification by sex and dietary intake. Data of 6,287 individuals participating in the European prospective investigation into cancer and nutrition were included in the analyses. Data on weight and waist circumference were followed up for 6.9 ± 2.5 years. Association of 69 tagSNPs with baseline BMI and annual changes in weight as well as waist circumference were investigated using linear regression analysis. Interactions with sex, GI and intake of carbohydrates, fat as well as saturated, monounsaturated and polyunsaturated fatty acids were examined by including multiplicative SNP-covariate terms into the regression model. Neither baseline BMI nor annual weight or waist circumference changes were significantly associated with variation in the selected genes in the entire study population after correction for multiple testing. One SNP (rs1164) in LPIN2 appeared to be significantly interacting with sex (p = 0.0003) and was associated with greater annual weight gain in men (56.8 ± 23.7 g/year per allele, p = 0.02) than in women (−25.5 ± 19.8 g/year per allele, p = 0.2). With respect to gene–nutrient interaction, we could not detect any significant interactions when accounting for multiple testing. Therefore, out of our six candidate genes, LPIN2 may be considered as a candidate for further studies.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-014-0385-7) contains supplementary material, which is available to authorized users.     

Gender differences between hypocretin/orexin knockout and wild type mice: age,body weight,body composition,metabolic markers,leptin and insulin resistance

Female hypocretin knockout (Hcrt KO) mice have increased body weight despite decreased food intake compared to wild type (WT) mice. In order to understand the nature of the increased body weight, we carried out a detailed study of Hcrt KO and WT, male, and female mice. Female KO mice showed consistently higher body weight than WT mice, from 4 to 20 months (20–60%). Fat, muscle, and free fluid levels were all significantly higher in adult (7–9 months) as well as old (18–20 months) female KO mice compared to age‐matched WT mice. Old male KO mice showed significantly higher fat content (150%) compared to age‐matched WT mice, but no significant change in body weight. Respiratory quotient (?19%) and metabolic rates (?14%) were significantly lower in KO mice compared to WT mice, regardless of gender or age. Female KO mice had significantly higher serum leptin levels (191%) than WT mice at 18–20 months, but no difference between male mice were observed. Conversely, insulin resistance was significantly higher in both male (73%) and female (93%) KO mice compared to age‐ and sex‐matched WT mice. We conclude that absence of the Hcrt peptide has gender‐specific effects. In contrast, Hcrt‐ataxin mice and human narcoleptics, with loss of the whole Hcrt cell, show weight gain in both sexes.

     

Design,synthesis, and preliminary in vitro and in vivo pharmacological evaluation of 2-{4-[4-(2,5-disubstituted thiazol-4-yl)phenylethyl]piperazin-1-yl}-1,8-naphthyridine-3-carbonitriles as atypical antipsychotic agents

A series of 2-{4-[4-(2,5-disubstituted thiazolyl)phenylethyl] piperazin-1-yl}-1,8-naphthyridine-3-carbonitriles were synthesized in an effort to prepare novel atypical antipsychotic agents. The compounds were synthesized either by microwave irradiation technique or by conventional synthesis and were characterized by spectral data (IR, ¹H NMR, and MS) and the purity was ascertained by microanalysis. The D₂ and 5-HT_2A affinity of the synthesized compounds was screened in vitro by radioligand displacement assays on membrane homogenates isolated from rat striatum and rat cortex, respectively. Furthermore, all the synthesized compounds were screened for their in vivo pharmacological activity in Swiss albino mice. The D₂ antagonism studies were performed using climbing mouse assay model and 5-HT_2A antagonism studies were performed using quipazine-induced head twitches in mice. It was observed that none of the new chemical entities exhibited catalepsy and 10f is the most active among the synthesized compounds with 5-HT_2A/D₂ ratio of 1.1286 although the standard drug risperidone exhibited 5-HT_2A/D₂ ratio of 1.0989.     

The effects of Goami No. 2 rice, a natural fiber-rich rice, on body weight and lipid metabolism

Objective : Increased intake of dietary fiber reduces the risk of obesity and type 2 diabetes. We assessed the effects of a fiber‐rich diet on body weight, adipokine concentrations, and the metabolism of glucose and lipids in non‐obese and obese subjects in Korea, where rice is the main source of dietary carbohydrates. Research Methods and Procedures : Eleven healthy, non‐obese and 10 obese subjects completed two 4‐week phases of individual isoenergetic food intake. During the control diet phase, subjects consumed standard rice; during the modified diet phase, subjects consumed equal proportions of fiber‐rich Goami No. 2 rice and standard rice. We used a randomized, controlled, crossover study design with a washout period of 6 weeks between the two phases. Results : After the modified diet phase, body weight was significantly lower in both the non‐obese and obese subjects (non‐obese, 57.0 ± 2.9 vs. 56.1 ± 2.8 kg, p = 0.001; obese, 67.7 ± 2.1 vs. 65.7 ± 2.0 kg, p < 0.001 for before vs. after). The BMI was significantly lower in obese subjects (26.9 ± 0.5 vs. 26.0 ± 0.6 kg/m², p < 0.001). The modified diet was associated with lower serum triacylglycerol (p < 0.01), total cholesterol (p < 0.01), low‐density lipoprotein cholesterol (p < 0.05), and C‐peptide (p < 0.05) concentrations in the obese subjects. Discussion : These results indicate that fiber‐rich Goami No. 2 rice has beneficial effects and may be therapeutically useful for obese subjects.     

Structural contributions of antipsychotic drugs to their therapeutic profiles and metabolic side effects

Antipsychotic drugs have various neuropharmacological properties as a result of their structural diversity. Despite their therapeutic benefits, most of the prescribed atypical antipsychotics can induce severe side effects, including weight gain, type II diabetes mellitus, and cardiovascular diseases. Among the developed atypical antipsychotic agents, tetracyclic dibenzodiazepine and thienobenzodiazepine compounds, particularly clozapine and olanzapine, are associated with the greatest weight gain and metabolic disturbances. However, the unique chemical structure of these compounds causes the low risk of side effects reported for typical antipsychotics (e.g. extrapyramidal symptoms and tardive dyskinesia). This report reviews the recent discovery of the potential role of the chemical structure of antipsychotics in their therapeutic properties and metabolic disturbances. By developing structure-activity relationship studies for atypical antipsychotics, we will improve our understanding of the structural modifications of these chemical classes that lead to reduced weight gain, which will be an invaluable step toward the discovery of the next generation of atypical antipsychotics. In this review, we suggest that a novel dibenzodiazepine or thienobenzodiazepine antipsychotic drug with lower affinity for H(1) receptors may significantly advance schizophrenia therapy.     

Genetic analyses of metabolic body weight,carcass weight and body conformation traits in Nordic dairy cattle

Improving feed efficiency in dairy cattle by animal breeding has started in the Nordic countries. One of the two traits included in the applied Saved feed index is called maintenance and it is based on the breeding values for metabolic BW (MBW). However, BW recording based on heart girth measurements is decreasing and recording based on scales is increasing only slowly, which may weaken the maintenance index in future. Therefore, the benefit of including correlated traits, like carcass weight and conformation traits, is of interest. In this study, we estimated genetic variation and genetic correlations for eight traits describing the energy requirement for maintenance in dairy cattle including: first, second and third parity MBW based on heart girth measurements, carcass weight (CARW) and predicted MBW (pMBW) based on predicted slaughter weight, and first parity conformation traits stature (ST), chest width (CW) and body depth (BD). The data consisted of 21 329 records from Finnish Ayrshire and 9 780 records from Holstein cows. Heritability estimates were 0.44, 0.53, 0.56, 0.52, 0.54, 0.60, 0.17 and 0.26 for MBW1, MBW2, MBW3, CARW, pMBW, ST, CW and BD, respectively. Estimated genetic correlations among MBW traits were strong (>0.95). Genetic correlations between slaughter traits (CARW and pMBW) and MBW traits were higher (from 0.77 to 0.90) than between conformation and MBW traits (from 0.47 to 0.70). Our results suggest that including information on carcass weight and body conformation as correlated traits into the maintenance index is beneficial when direct BW measurements are not available or are difficult or expensive to obtain.     

[3H]Nemonapride and [3H]Spiperone Label Equivalent Numbers of D2 and D3 Dopamine Receptors in a Range of Tissues and Under Different Conditions

Abstract: [³H]Nemonapride and [³H]spiperone are very widely used to study dopaminergic systems in vitro and in vivo, but it has been reported that [³H]nemonapride and [³H]spiperone give markedly different B _max values for preparations of D₂ dopamine receptors from recombinant cell lines or animal tissues. We have used the two radioligands in parallel to study a range of dopamine receptors [D_2(short), D_2(long), and D₃] in different buffers. B _max values derived using either radioligand differ by an average of <20%, independent of receptor type or buffer conditions. All competition experiments show that the two ligands compete at a single site. It seems that [³H]spiperone and [³H]nemonapride do not differentiate between different forms or populations of D₂-like receptors.     

Joint effects of porcine leptin and leptin receptor polymorphisms on productivity and quality traits

Leptin signalling plays a fundamental role in growth, fatness and body composition. The aim of this study was to investigate the porcine LEP gene sequence in an Iberian × Landrace experimental cross to identify polymorphisms associated with productivity and quality traits. Because of the documented effects on these traits of the LEPR c.1987C>T polymorphism, the LEP and LEPR c.1987C>T polymorphisms and their interactions have been jointly investigated. The LEP gene sequencing has allowed the identification of 39 polymorphisms, eight of which are novel. Three intronic SNPs, LEP g.1382C>T, LEP g.1387C>T and LEP g.1723A>G, have been genotyped, and association analyses have been carried out. Analyses of LEP g.1387C>T, fully linked to LEP g.1382C>T, have revealed additive effects on live and carcass weights and dominant effects on several backfat thickness measurements. Novel effects of both LEP and LEPR polymorphisms on fatty acid composition in subcutaneous fat have been detected, probably mediated through the effects on fatness. The results reported here suggest that the T alleles of both LEP g.1387C>T and LEPR c.1987C>T, which are fixed in the Iberian pigs, would lead to an increase in growth, fatness and saturated fatty acid content in fat, which could be explained by an increased feed intake.     

5-HT(2A) and D(2) receptor blockade increases cortical DA release via 5-HT(1A) receptor activation: a possible mechanism of atypical antipsychotic-induced cortical dopamine release

Atypical antipsychotic drugs (APDs), all of which are relatively more potent as serotonin (5-HT)(2A) than dopamine D(2) antagonists, may improve negative symptoms and cognitive dysfunction in schizophrenia, in part, via increasing cortical dopamine release. 5-HT(1A) agonism has been also suggested to contribute to the ability to increase cortical dopamine release. The present study tested the hypothesis that clozapine, olanzapine, risperidone, and perhaps other atypical APDs, increase dopamine release in rat medial prefrontal cortex (mPFC) via 5-HT(1A) receptor activation, as a result of the blockade of 5-HT(2A) and D(2) receptors. M100907 (0.1 mg/kg), a 5-HT(2A) antagonist, significantly increased the ability of both S:(-)-sulpiride (10 mg/kg), a D(2) antagonist devoid of 5-HT(1A) affinity, and R:(+)-8-OH-DPAT (0.05 mg/kg), a 5-HT(1A) agonist, to increase mPFC dopamine release. These effects of M100907 were abolished by WAY100635 (0.05 mg/kg), a 5-HT(1A) antagonist, which by itself has no effect on mPFC dopamine release. WAY100635 (0.2 mg/kg) also reversed the ability of clozapine (20 mg/kg), olanzapine (1 mg/kg), risperidone (1 mg/kg), and the R:(+)-8-OH-DPAT (0.2 mg/kg) to increase mPFC dopamine release. Clozapine is a direct acting 5-HT(1A) partial agonist, whereas olanzapine and risperidone are not. These results suggest that the atypical APDs via 5-HT(2A) and D(2) receptor blockade, regardless of intrinsic 5-HT(1A) affinity, may promote the ability of 5-HT(1A) receptor stimulation to increase mPFC DA release, and provide additional evidence that coadministration of 5-HT(2A) antagonists and typical APDs, which are D(2) antagonists, may facilitate 5-HT(1A) agonist activity.