TAAR1 agonists improve glycemic control, reduce body weight and modulate neurocircuits governing energy balance and feeding.

OBJECTIVE: Metabolic Syndrome, which can be induced or exacerbated by current antipsychotic drugs (APDs), is highly prevalent in schizophrenia patients. Recent preclinical and clinical evidence suggest that agonists at trace amine-associated receptor 1 (TAAR1) have potential as a new treatment option for schizophrenia. Intriguingly, preclinical tudies have also identified TAAR1 as a novel regulator of metabolic control. Here we evaluated the effects of three TAAR1 agonists, including the clinical development candidate ulotaront, on body weight, metabolic parameters and modulation of neurocircuits implicated in homeostatic and hedonic feeding. METHODS: Effects of TAAR1 agonists (ulotaront, RO5166017 and/or RO5263397) on body weight, food intake and/or metabolic parameters were investigated in rats fed a high-fat diet (HFD) and in a mouse model of diet-induced obesity (DIO). Body weight effects were also determined in a rat and mouse model of olanzapine-, and corticosterone-induced body weight gain, respectively. Glucose tolerance was assessed in lean and diabetic db/db mice and fasting plasma glucose and insulin examined in DIO mice. Effects on gastric emptying were evaluated in lean mice and rats. Drug-induced neurocircuit modulation was evaluated in mice using whole-brain imaging of c-fos protein expression. RESULTS: TAAR1 agonists improved oral glucose tolerance by inhibiting gastric emptying. Sub-chronic administration of ulotaront in rats fed a HFD produced a dose-dependent reduction in body weight, food intake and liver triglycerides compared to vehicle controls. In addition, a more rapid reversal of olanzapine-induced weight gain and food intake was observed in HFD rats switched to ulotaront or RO5263397 treatment compared to those switched to vehicle. Chronic ulotaront administration also reduced body weight and improved glycemic control in DIO mice, and normalized corticosterone-induced body weight gain in mice. TAAR1 activation increased neuronal activity in discrete homeostatic and hedonic feeding centers located in the dorsal vagal complex and hypothalamus with concurrent activation of several limbic structures. CONCLUSION: The current data demonstrate that TAAR1 agonists, as a class, not only lack APD-induced metabolic liabilities but can reduce body weight and improve glycemic control in rodent models. The underlying mechanisms likely include TAAR1-mediated peripheral effects on glucose homeostasis and gastric emptying as well as central regulation of energy balance and food intake.

Discovery of Highly Selective Inhibitors of Calmodulin-Dependent Kinases That Restore Insulin Sensitivity in the Diet-Induced Obesity in Vivo Mouse Model.

Polymorphisms in the region of the calmodulin-dependent kinase isoform D (CaMK1D) gene are associated with increased incidence of diabetes, with the most common polymorphism resulting in increased recognition by transcription factors and increased protein expression. While reducing CaMK1D expression has a potentially beneficial effect on glucose processing in human hepatocytes, there are no known selective inhibitors of CaMK1 kinases that can be used to validate or translate these findings. Here we describe the development of a series of potent, selective, and drug-like CaMK1 inhibitors that are able to provide significant free target cover in mouse models and are therefore useful as in vivo tool compounds. Our results show that a lead compound from this series improves insulin sensitivity and glucose control in the diet-induced obesity mouse model after both acute and chronic administration, providing the first in vivo validation of CaMK1D as a target for diabetes therapeutics.

Investigation of impulsivity in binge-eating rats in a delay-discounting task and its prevention by the d-amphetamine prodrug, lisdexamfetamine.

Freely-fed, female, rats were trained in a two-lever, delay-discounting task: one lever delivered a single chocolate-flavoured pellet immediately and the other a three-pellet reward after increasing delay (0, 4, 8, 16, 32 s). Rats were divided into two groups (i.e. binge-eating rats given irregular, limited access to chocolate in addition to normal chow and controls maintained on normal chow). Both groups exhibited increased preference for the immediate reward as the delay interval was lengthened. The discounting rate was significantly greater in binge-eating rats than non-binge-eating controls, especially as the behaviour became more established indicating that increased impulsivity and intolerance of delayed reward are part of the psychopathology of binge-eating. Lisdexamfetamine (0.8 mg/kg, orally ( d-amphetamine base)) reversed the reduced preference of binge-eating rats for larger rewards at delay intervals of 4 s, 8 s and 32 s and across all sessions. Lisdexamfetamine-treated binge-eating rats consumed the same number of pellets as vehicle-treated, binge-eating rats and non-binge-eating controls eliminating the possibility lisdexamfetamine's actions on appetite or satiety mediated its effects on operant responding for food pellets in delay-discounting. In summary, binge-eating rats showed increased impulsive choice compared with non-binge-eating controls that was reversed by lisdexamfetamine, complementing results showing lisdexamfetamine reduced impulsiveness scores in patients with binge-eating disorder.

Lisdexamfetamine reduces the compulsive and perseverative behaviour of binge-eating rats in a novel food reward/punished responding conflict model.

Compulsive and perseverative behaviour in binge-eating, female, Wistar rats was investigated in a novel food reward/punished responding conflict model. Rats were trained to perform the conditioned avoidance response task. When proficient, the paradigm was altered to a food-associated conflict test by placing a chocolate-filled jar (empty jar for controls) in one compartment of the shuttle box. Entry into the compartment with the jar triggered the conditioning stimulus after a variable interval, and foot-shock 10 seconds later if the rat did not leave. Residence in the 'safe' compartment with no jar did not initiate trials or foot-shocks. By frequently entering the chocolate-paired compartment, binge-eating rats completed their 10 trials more quickly than non-binge controls. Binge-eating rats spent a greater percentage of the session in the chocolate-paired compartment, received foot-shocks more frequently, and tolerated foot-shocks for longer periods; all consistent with compulsive and perseverative behaviour. The d-amphetamine prodrug, lisdexamfetamine, has recently received US approval for the treatment of moderate to severe binge-eating disorder in adults. Lisdexamfetamine (0.8 mg/kg po [d-amphetamine base]) decreased chocolate consumption by binge-eating rats by 55% and markedly reduced compulsive and perseverative responding in the model. These findings complement clinical results showing lisdexamfetamine reduced compulsiveness scores in subjects with binge-eating disorder.

A sustained release formulation of novel quininib-hyaluronan microneedles inhibits angiogenesis and retinal vascular permeability in vivo.

Pathologic neovascularisation and ocular permeability are hallmarks of proliferative diabetic retinopathy and age-related macular degeneration. Current pharmacologic interventions targeting VEGF are effective in only 30-60% of patients and require multiple intraocular injections associated with iatrogenic infection. Thus, our goal is to develop novel small molecule drugs that are VEGF-independent are amenable to sustained ocular-release, and which reduce retinal angiogenesis and retinal vascular permeability. Here, the anti-angiogenic drug quininib was formulated into hyaluronan (HA) microneedles whose safety and efficacy was evaluated in vivo. Quininib-HA microneedles were formulated via desolvation from quininib-HA solution and subsequent cross-linking with 4-arm-PEG-amine prior to freeze-drying. Scanning electron microscopy revealed hollow needle-shaped particle ultrastructure, with a zeta potential of -35.5mV determined by electrophoretic light scattering. The incorporation efficiency and pharmacokinetic profile of quininib released in vitro from the microneedles was quantified by HPLC. Quininib incorporation into these microneedles was 90%. In vitro, 20% quininib was released over 4months; or in the presence of increasing concentrations of hyaluronidase, 60% incorporated quininib was released over 4months. Zebrafish hyaloid vasculature assays demonstrated quininib released from these microneedles significantly (p<0.0001) inhibited ocular developmental angiogenesis compared to control. Sustained amelioration of retinal vascular permeability (RVP) was demonstrated using a bespoke cysteinyl leukotriene induced rodent model. Quininib-HA microparticles significantly inhibited RVP in Brown Norway rats one month after administration compared to neat quininib control (p=0.0071). In summary, quininib-HA microneedles allow for sustained release of quininib; are safe in vivo and quininib released from these microneedles effectively inhibits angiogenesis and RVP in vivo.

Effects of lisdexamfetamine in a rat model of binge-eating.

Binge-eating disorder is a common psychiatric disorder affecting ~2% of adults. Binge-eating was initiated in freely-fed, lean, adult, female rats by giving unpredictable, intermittent access to ground, milk chocolate over four weeks. The rats avidly consumed chocolate during 2 hr binge sessions, with compensatory reductions of normal chow intake in these sessions and the days thereafter. Bodyweights of binge-eating rats were normal. The model's predictive validity was explored using nalmefene (0.1-1.0mg/kg), R-baclofen (1.0-10mg/kg) and SB-334867 (3.0-30 mg/kg) (orexin-1 antagonist), which all selectively decreased chocolate bingeing without reducing chow intake. Sibutramine (0.3-5.0mg/kg) non-selectively reduced chocolate and chow consumption. Olanzapine (0.3-3.0mg/kg) was without effect and rolipram (1.0-10mg/kg) abolished all ingestive behaviour. The pro-drug, lisdexamfetamine (LDX; 0.1-1.5mg/kg), dose-dependently reduced chocolate bingeing by ⩽ 71% without significantly decreasing normal chow intake. Its metabolite, D-amphetamine (0.1-1.0mg/kg), dose-dependently and preferentially decreased chocolate bingeing ⩽ 56%. Using selective antagonists to characterize LDX's actions revealed the reduction of chocolate bingeing was partially blocked by prazosin (α1-adrenoceptor; 0.3 and 1.0mg/kg) and possibly by SCH-23390 (D1; 0.1mg/kg). RX821002 (α2-adrenoceptor; 0.1 and 0.3mg/kg) and raclopride (D2; 0.3 and 0.5mg/kg) were without effect. The results indicate that LDX, via its metabolite, d-amphetamine, reduces chocolate bingeing, partly by indirect activation of α1-adrenoceptors and perhaps D1 receptors.

Characterisation of pain responses in the high fat diet/streptozotocin model of diabetes and the analgesic effects of antidiabetic treatments.

Chronic pain is a common complication of diabetes. The aim of the present study was to characterise pain behaviour in a high fat diet/streptozotocin (HFD/STZ) model of diabetes in the rat, investigate spinal mechanisms, and determine the effects of antidiabetic interventions. Three-week consumption of a high fat diet followed by single injection of STZ (45 mgkg(-1)) produced sustained changes in plasma insulin and glucose until day 120. Hindpaw mechanical withdrawal thresholds were significantly lowered in the model, but mechanically evoked responses of spinal neurones were unaltered, compared to HFD/vehicle rats. HFD/STZ rats had significantly lower numbers of spinal Iba-1 positive cells (morphologically identified as activated microglia) and spinal GFAP immunofluorescence (a marker of astrogliosis) in the spinal cord at day 50, compared to time-matched controls. The PPARγ ligand pioglitazone (10 mgkg(-1)) did not alter HFD/STZ induced metabolic changes or hindpaw withdrawal thresholds of HFD/STZ rats. Daily linagliptin (3 mgkg(-1)) and metformin (200 mgkg(-1)) from day 4 after model induction did not alter plasma glucose or insulin in HFD/STZ rats but significantly prevented changes in the mechanical withdrawal thresholds. The demonstration that currently prescribed antidiabetic drugs prevent aberrant pain behaviour supports the use of this model to investigate pain mechanisms associated with diabetes.

Combination of the sodium-glucose cotransporter-2 inhibitor empagliflozin with orlistat or sibutramine further improves the body-weight reduction and glucose homeostasis of obese rats fed a cafeteria diet.

The present study assessed the potential of the sodium glucose-linked transporter (SGLT)-2 inhibitor empagliflozin to decrease body weight when administered alone or in combination with the clinically effective weight-loss agents orlistat and sibutramine in obese rats fed a cafeteria diet. Female Wistar rats were exposed to a cafeteria diet to induce obesity. Empagliflozin was dosed once daily (10, 30, and 60 mg/kg) for 28 days. Combination studies were subsequently performed using a submaximal empagliflozin dose (10 mg/kg) with either sibutramine or orlistat. Body weight, food, and water intake were recorded daily. The effect of drug treatment on glucose tolerance, relevant plasma parameters, and carcass composition was determined. Empagliflozin dose-dependently reduced body weight, plasma leptin, and body fat though increased urinary glucose excretion. The combination of empagliflozin and orlistat significantly reduced body weight compared to animals treated with either drug alone, and significantly improved glucose tolerance, plasma insulin, and leptin compared to vehicle-treated controls. The effect of sibutramine to improve glycemic control in an oral glucose-tolerance test was also significantly increased, with empagliflozin and combination treatment leading to a reduction in carcass fat greater than that observed with either drug alone. These data demonstrate that empagliflozin reduces body weight in cafeteria-fed obese rats. In combination studies, empagliflozin further improved the body-weight or body-fat loss of animals in comparison to orlistat or sibutramine alone. Such studies may indicate improved strategies for the treatment of obese patients with prediabetes or type 2 diabetes.

Effect of linagliptin, alone and in combination with voglibose or exendin-4, on glucose control in male ZDF rats.

The effects of the dipeptidyl peptidase-4 (DPP-4) inhibitor, linagliptin, alone and in combination with voglibose or exendin-4, on glycaemic control and body weight were assessed in an animal model of type 2 diabetes. Voglibose is an α-glucosidase inhibitor but also increases glucagon-like peptide 1 (GLP-1). Exendin-4 is a GLP-1 receptor agonist. Male Zucker Diabetic Fatty (ZDF) rats were dosed for 3 days, fasted overnight and a sucrose/glucose tolerance test was performed. Linagliptin (1mg/kg po) improved glucose tolerance by increasing plasma GLP-1 (active) and insulin secretion, whilst having no effect on body weight. Voglibose (1 and 10mg/kg po) reduced body weight, improved glycaemic control, reduced plasma insulin and increased total but not active GLP-1. The combination of linagliptin and voglibose significantly reduced body weight, improved glycaemic control and reduced plasma insulin compared to linagliptin alone. Furthermore, linagliptin plus voglibose produced a marked increase in GLP-1 (active) at 5min post-sucrose, compared to linagliptin, possibly because linagliptin prevented the degradation of GLP-1 secreted in response to voglibose. Exendin-4 (10µg/kg sc) significantly reduced body weight, improved glucose tolerance but reduced GLP-1 (active). The combination of linagliptin and exendin-4 significantly reduced body weight and improved glycaemic control but had no effect on plasma GLP-1. Overall it did not markedly improve glycaemic control compared to the individual drugs. The improved glucose control, reduced body weight and markedly increased plasma GLP-1 levels in animals given linagliptin with voglibose, suggests that this combination may be particularly beneficial in the treatment of type 2 diabetes.

Effects of the DPP-4 inhibitor, linagliptin, in diet-induced obese rats: a comparison in naive and exenatide-treated animals.

BACKGROUND: To assess the chronic effect of the DPP-4 inhibitor, linagliptin, alone, in combination with exenatide, and during exenatide withdrawal, in diet-induced obese (DIO) rats. METHODS: Female Wistar rats were exposed to a cafeteria diet to induce obesity. Animals were then dosed with vehicle or linagliptin (3 mg/kg PO) orally once-daily for a 28 day period. In a subsequent study, rats received exenatide (either 3 or 30 microg/kg/day) or vehicle by osmotic mini-pump for 28 days. In addition, groups of animals were dosed orally with linagliptin either alone or in combination with a 3 microg/kg/day exenatide dose for the study duration. In a final study, rats were administered exenatide (30 microg/kg/day) or vehicle by osmotic mini-pump for eleven days. Subsequently, exenatide-treated animals were transferred to vehicle or continued exenatide infusion for a further ten days. Animals transferred from exenatide to vehicle were also dosed orally with either vehicle or linagliptin. In all studies, body weight, food and water intake were recorded daily and relevant plasma parameters and carcass composition were determined. RESULTS: In contrast to exenatide, linagliptin did not significantly reduce body weight or carcass fat in DIO rats versus controls. Linagliptin augmented the effect of exenatide to reduce body fat when given in combination but did not affect the body weight response. In rats withdrawn from exenatide, weight regain was observed such that body weight was not significantly different to controls. Linagliptin reduced weight regain after withdrawal of exenatide such that a significant difference from controls was evident. CONCLUSIONS: These data demonstrate that linagliptin does not significantly alter body weight in either untreated or exenatide-treated DIO rats, although it delays weight gain after exenatide withdrawal. This finding may suggest the utility of DPP-4 inhibitors in reducing body weight during periods of weight gain.

Animal models to explore the effects of CNS drugs on food intake and energy expenditure.

Obesity has reached epidemic proportions globally with an increasing incidence not just in Western cultures but also Mexico, Brazil, China and parts of Africa. In terms of pharmacological intervention, the track record of drug treatments for obesity is poor, especially in the case of centrally acting medicines, and there remains an unmet need for the development of safer compounds delivering superior efficacy. Animal models are of importance not only in detecting changes in food intake, energy expenditure and body weight but also providing confidence that these changes are behaviourally specific and not a result of drug-induced side effects. We review animal models of feeding behaviour that are used to aid our understanding of the control of body weight and energy regulation with special reference to CNS-acting drugs. The use of such models in the discovery of new drugs for the treatment of obesity is given particular emphasis. This article is part of a Special Issue entitled 'Central Control of Food Intake'.

The utility of animal models to evaluate novel anti-obesity agents.

The global incidence of obesity continues to rise and is a major driver of morbidity and mortality through cardiovascular and cerebrovascular diseases. Animal models used in the discovery of novel treatments for obesity range from straightforward measures of food intake in lean rodents to long-term studies in animals exhibiting obesity due to the continuous access to diets high in fat. The utility of these animal models can be extended to determine, for example, that weight loss is due to fat loss and/or assess whether beneficial changes in key plasma parameters (e.g. insulin) are evident. In addition, behavioural models such as the behavioural satiety sequence can be used to confirm that a drug treatment has a selective effect on food intake. Typically, animal models have excellent predictive validity whereby drug-induced weight loss in rodents subsequently translates to weight loss in man. However, despite this, at the time of writing orlistat (Europe; USA) remains the only drug currently marketed for the treatment of obesity, with sibutramine having recently been withdrawn from sale globally due to the increased incidence of serious, non-fatal cardiovascular events. While the utility of rodent models in predicting clinical weight loss is detailed, the review also discusses whether animals can be used to predict adverse events such as those seen with recent anti-obesity drugs in the clinic.

Tetrahydrocarboline analogs as MCH-1 antagonists.

A new series of tetrahydrocarbolines with potent MCH-1 antagonist activity were synthesized, using a conformationally constrained design approach towards optimizing pharmacokinetic properties. Two compounds from this series were progressed to a 5-day diet-induced obesity mouse screening model to evaluate their potential as weight loss agents. Both compounds produced a highly significant reduction in weight, which was attributed to their improved pharmacokinetic profile.

Synthesis and SAR of 4-aryl-1-(indazol-5-yl)pyridin-2(1H)ones as MCH-1 antagonists for the treatment of obesity.

A new series of 4-aryl-1-(indazol-5-yl)pyridin-2(1H)ones possessing MCH-1 receptor antagonism is presented. Suzuki coupling of boronic acids with key triflate 6 allowed rapid generation of a range of analogs. The SAR of the MCH-1 receptor was explored with a variety of aryl and heterocyclic moieties. Selected compounds were studied in a five-day diet induced obese mouse model to evaluate their potential use as weight loss agents.

5-(pyridinon-1-yl)indazoles and 5-(furopyridinon-5-yl)indazoles as MCH-1 antagonists.

A new series of 5-(pyridinon-1-yl)indazoles with MCH-1 antagonist activity were synthesized. Potential cardiovascular risk for these compounds was assessed based upon their interaction with the hERG potassium channel in a mini-patch clamp assay. Selected compounds were studied in a 5-day diet-induced obese mouse model to evaluate their potential use as weight loss agents. Structural modification of the 5-(pyridinon-1-yl)indazoles to give 5-(furopyridinon-5-yl)indazoles provided compounds with enhanced pharmacokinetic properties and improved efficacy.

Prokineticin 2 is a hypothalamic neuropeptide that potently inhibits food intake.

OBJECTIVE: Prokineticin 2 (PK2) is a hypothalamic neuropeptide expressed in central nervous system areas known to be involved in food intake. We therefore hypothesized that PK2 plays a role in energy homeostasis. RESEARCH DESIGN AND METHODS: We investigated the effect of nutritional status on hypothalamic PK2 expression and effects of PK2 on the regulation of food intake by intracerebroventricular (ICV) injection of PK2 and anti-PK2 antibody. Subsequently, we investigated the potential mechanism of action by determining sites of neuronal activation after ICV injection of PK2, the hypothalamic site of action of PK2, and interaction between PK2 and other hypothalamic neuropeptides regulating energy homeostasis. To investigate PK2's potential as a therapeutic target, we investigated the effect of chronic administration in lean and obese mice. RESULTS: Hypothalamic PK2 expression was reduced by fasting. ICV administration of PK2 to rats potently inhibited food intake, whereas anti-PK2 antibody increased food intake, suggesting that PK2 is an anorectic neuropeptide. ICV administration of PK2 increased c-fos expression in proopiomelanocortin neurons of the arcuate nucleus (ARC) of the hypothalamus. In keeping with this, PK2 administration into the ARC reduced food intake and PK2 increased the release of alpha-melanocyte-stimulating hormone (alpha-MSH) from ex vivo hypothalamic explants. In addition, ICV coadministration of the alpha-MSH antagonist agouti-related peptide blocked the anorexigenic effects of PK2. Chronic peripheral administration of PK2 reduced food and body weight in lean and obese mice. CONCLUSIONS: This is the first report showing that PK2 has a role in appetite regulation and its anorectic effect is mediated partly via the melanocortin system.

Mixed valence Creutz-Taube ion analogues incorporating thiacrowns: synthesis, structure, physical properties, and computational studies.

A series of nine new complexes incorporating [Ru(II)Cl([n]aneS(3))] (n = 12, 14, 16) metal centers bridged by three ditopic ligands containing two monodentate sites (pyrazine, 4,4'-bipyridine, and 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine) have been synthesized and fully characterized. The solid-state structures of three of the complexes have been further characterized by X-ray crystallography studies. Intermetallic interactions within the new systems have been probed using electrochemistry and optical spectroscopy. Cyclic voltammetry reveals that the three pyrazine bridged systems display two separate Ru(III)/(II) redox couples. Using spectroelectrochemistry, we have investigated the optical properties of these mixed valence, Creutz-Taube ion analogues. An analysis of the intervalence charge transfer bands for the complexes revealed that, despite possessing the same donor sets, the electronic delocalization within these systems is modulated by the nature of the coordinated thiacrown. Computational modeling using density function theory offers further evidence of interaction between metal centers and provides insights into how these interactions are mediated.

A comparison of the effects of the CB(1) receptor antagonist SR141716A, pre-feeding and changed palatability on the microstructure of ingestive behaviour.

RATIONALE: The cannabinoid CB(1) receptor inverse agonist SR141716A (rimonabant) is known to cause hypophagia and this study uses microstructural data to elucidate the relevant behavioural mechanisms. OBJECTIVES: The aim of these studies was to determine the behavioural changes induced by SR141716A in animals consuming either a fat or carbohydrate solution. These behavioural changes were directly compared with those induced by behavioural manipulations that modify motivational state and palatability. METHODS: Male hooded Lister rats drank a highly palatable fat emulsion (10% Intralipid) or a carbohydrate solution (10% sucrose) during 30-min test sessions. Microstructural analyses of licking patterns were made after either administration of SR141716A (0, 0.3, 1 and 3 mg/kg, ip) or one of the after behavioural manipulations: pre-feeding, addition of quinine to the fat solution or changes in sucrose concentration. RESULTS: Intake of the fat solution was decreased after both the drug treatment and the behavioural manipulations of pre-feeding and addition of quinine. Pre-feeding and SR141716A-induced reductions were mediated via changes in bout number whereas addition of quinine caused a decrease in bout size. Although sucrose drinking was also decreased by pre-feeding, reduced sucrose concentration and SR141716A, the drug did not significantly alter the microstructure of intake. CONCLUSIONS: The effects of SR141716A on consumption of Intralipid solutions are likely to reflect changes in motivational state rather than modified hedonic impact.

The cannabinoid CB1 receptor inverse agonist, rimonabant, modifies body weight and adiponectin function in diet-induced obese rats as a consequence of reduced food intake.

The cannabinoid CB1 receptor inverse agonist rimonabant induces hypophagia and body weight loss. Reduced body weight may potentially be due to decreased food intake or to direct metabolic effects of drug administration on energy expenditure. This study uses a paired-feeding protocol to quantify the contributions of energy intake to rimonabant-induced body weight loss. Diet-induced obese (DIO) rats were dosed with rimonabant (3, 10 mg/kg PO once daily) and matched with pair-fed controls. Food intake and body weight were measured daily. Blood samples and adipose tissue were collected on day 15 for measurement of plasma adiponectin and adiponectin mRNA levels. DIO rats treated with rimonabant and pair-fed controls showed very similar changes in body weight. Although tolerance developed to the anorectic effect of rimonabant, total food intake was significantly decreased over the 14-day study period and fully accounted for the observed reductions in body weight. Adiponectin mRNA and plasma adiponectin were elevated in vehicle-treated chow-fed animals compared to obese controls, and did not differ between rimonabant-treated and pair-fed animals. The similarities between rimonabant-treated and pair-fed animals in body weight loss and the absence of differences in measures of adiponectin activity between drug-treated and pair-fed animals suggest that the outcomes of this experiment were solely mediated by the drug-induced reduction in food intake.

Kinetically locked, trinuclear Ru(II) metallo-macrocycles--synthesis, electrochemical, and optical properties.

Using a [Ru(II)([9]aneS3)] templating moiety, kinetically-locked, metallomacrocycles incorporating adenine based ligands have been synthesised through self-assembly. The kinetically robust nature of these structures is confirmed by electrochemical studies: each can be reversibly oxidised in a four-member redox series, containing two formally mixed valence states. Unusually, the electrochemically derived comproportionation constants for these mixed valence states are very different, suggesting that intermetallic coupling differs between the two states. Spectroelectochemistry studies confirm that while the [Ru(II)2Ru(III)] state is valence localised, the [Ru(II)Ru(III)2] state is electronically delocalised. Mechanisms by which this switching effect could occur, which involve the unusual connectivities in these mixed valence species, are presented.