Hypothalamic Regulation Of Food Intake Research Articles

Medications for the treatment of obesity.

After several years with no real therapeutic alternatives, the management of obesity is entering a new era with the development of new surgical and endoscopic bariatric techniques, digital therapeutics and the arrival of new classes of drugs. New medication treatments aim to reduce food intake, targeting the hypothalamic regulation of food intake and satiety. The mechanism of their action remains poorly understood but, combines weight reduction and amelioration of cardiometabolic risk factors with a favorable benefit-risk balance and known side effects, mainly digestive. The future will tell us how these drugs will find their place in the management of this chronic disease that is obesity.

215 Impact of Maternal Diabetes on Neonatal Body Composition, Energy Homeostasis and Hypothalamic Salivary Gene Expression

OBJECTIVES/GOALS: Infants of diabetic mothers (IDMs) may exhibit decreased oral intake, requiring nasogastric feedings and prolonged hospitalization. We hypothesize that increased insulin exposure and resulting overgrowth in utero disrupts hypothalamic regulation of food intake, correlates to body composition and impacts feeding in IDMs. METHODS/STUDY POPULATION: Infants born at ≥ 35 weeks gestation to mothers with gestational or type II diabetes (IDM cohort), and normoglycemic mothers (control cohort) were recruited. Infants born to mothers with Type I DM or preeclampsia and with a history of intrauterine growth restriction, opioid exposure, or major congenital anomalies were excluded. Salivary expression of known hunger signaling genes 5AMP-activated protein kinase (AMPK), Neuropeptide Y receptor Y2 (NPY2R), leptin (LEP), ghrelin (GHRL), proopiomelanocortin (POMC), and adiponectin (ADIPOQ) were quantified using RT-qPCR. Body composition was assessed via skinfold measurements and compared and correlated between cohorts. Feeding outcomes were recorded. RESULTS/ANTICIPATED RESULTS: 23 infants were recruited in each cohort. POMC and AMPK were expressed by 71% and 88% of infants respectively in both cohorts. NPY2R was expressed by 79% and 83% of the diabetic cohort and normoglycemia cohort respectively, while GHRL was expressed by 75% and 79% of the diabetic cohort and normoglycemia cohort, respectively. LEP and ADIPOQ were not reliably expressed in either cohort. Infants with a higher body fat percentage were less likely to express NPY2R (OR= 0.76). There was no significant association between body fat percentage and expression of AMPK, POMC, or GHRL. Only 3 IDMs were noted by providers to exhibit poor oral intake, limiting our ability to correlate gene expression and body composition with feeding outcomes. DISCUSSION/SIGNIFICANCE: Non-invasive assessment of hunger signaling gene expression is possible through salivary analysis of AMPK, POMC, NPY2R, and GHRL. Given the paucity of IDMs with poor feeding in our study, future studies should target IDMs requiring feeding support to understand mechanisms driving aberrant feeding behavior.

The BDNF rs7934165 polymorphism is a biomarker of central obesity and cardiometabolic risk in Mexican women.

Brain-derived neurotrophic factor (BDNF) is a cornerstone in the hypothalamic regulation of food intake and energy homeostasis. Polymorphisms in the BDNF gene may thus contribute to obesity traits. The aim of this investigation was to analyze the association of rs6265 and rs7934165 BDNF polymorphisms in women from Northeast Mexico classified as obese or overweight using their BMI and waist-to-height ratio (WHtR). A total of 296 women were enrolled and further divided into normal weight and obese overweight groups according to their BMI status and WHtR classifications, which were low and high at < 0.50 and ≥ 0.50, respectively. Genotyping of BDNF rs6265 and rs7934165 polymorphisms was performed using a TaqMan assay. Distinct anthropometric, biochemical, clinical, and dietary parameters were obtained and used as covariates in the statistical analyses. The rs6265-G allele and its homozygote state (GG) were the most prominent without statistically significant differences between groups (p = 0.412). The study of rs7934165 with BMI showed marginal associations. Moreover, the rs7934165-AA genotype was more frequent among individuals with a high WHtR than those with a low WHtR (43.4 vs. 25.2%, p = 0.01). This association was maintained after adjustments for age and caloric intake through logistic regression analysis (OR = 2.20, 95% CI = 1.15-4.18, p = 0.016). The present study indicates that the BDNF-rs7934165-AA genotype is associated with a higher WHtR which is related to central obesity and its comorbidities. This suggests that this SNP could act as a potential biomarker for central obesity and cardiometabolic risk.

Serotonin as a Regulator of Leptin-Mediated Food Intake Control Within a Novel Neuronal Circuit Between the Hypothalamus and Raphe Nuclei

The onset and exacerbation of obesity involves the overproduction of the adipocyte-derived hormone leptin, a key mediator of homeostatic appetite regulation and a signal for satiety. Although leptin’s hypothalamic regulation of food intake has been extensively investigated, its role in tandem with the anorectic neurotransmitter serotonin (5-HT) has been less characterized. 5-HT is synthesized in the dorsal raphe nucleus (DRN) where anatomical projections to many hypothalamic nuclei have previously been identified. Preliminary studies in our lab have: (1) identified serotonergic neurons responsive to leptin in the DRN that project to the arcuate nucleus (ARC) of the hypothalamus and (2) demonstrated leptin injected into the DRN significantly decreases food intake. The objective of the current study was to identify the role of 5-HT in leptin’s regulation of food intake first within the DRN, then between the DRN and the ARC. Adult male Sprague Dawley rats underwent stereotaxic surgery for guide cannula implantation in the DRN. After recovery, animals were administered 100 µg of p-chlorophenylalanine (PCPA), an inhibitor of 5-HT synthesis, in the DRN each day for four days. On the fourth day, leptin was also administered in the DRN (5 µg/rat) and food intake was measured over a 24-hour time course. ANOVA analysis revealed a significant difference in 24-hour food intake [F (3, 18) = 3.972; P = 0.0246] and post-hoc analysis showed that animals treated with leptin significantly decreased food intake (17.2 ± 2.0 g) compared to control rats (25.4 ± 0.9 g), whereas PCPA-treated rats did not differ from the control rats, suggesting that depletion of 5-HT attenuated leptin’s ability to regulate food intake within the DRN. To examine the role of 5-HT on leptin’s hypothalamic action, a subsequent experiment was conducted by implanting an additional cannula into the ARC for the administration of leptin or vehicle on the fourth day of treatment. ANOVA analysis revealed a significant difference in 24-hour food intake [F (3, 16) = 5.998; P = 0.0061] and post-hoc analysis showed that only rats treated with leptin in the ARC significantly decreased food intake (14.0 ± 1.5 g) compared to controls (21.8 ± 0.5 g). 5-HT depletion was assessed post-mortem using immunohistochemistry and was later quantified. Collectively, these results demonstrate that leptin’s ability to regulate food intake is dependent on 5-HT, regardless of the area of regulation (i.e. DRN or the hypothalamus).

Signal Transduction and Pathogenic Modifications at the Melanocortin-4 Receptor: A Structural Perspective.

The melanocortin-4 receptor (MC4R) can be endogenously activated by binding of melanocyte-stimulating hormones (MSH), which mediates anorexigenic effects. In contrast, the agouti-related peptide (AgRP) acts as an endogenous inverse agonist and suppresses ligand-independent basal signaling activity (orexigenic effects). Binding of ligands to MC4R leads to the activation of different G-protein subtypes or arrestin and concomitant signaling pathways. This receptor is a key protein in the hypothalamic regulation of food intake and energy expenditure and naturally-occurring inactivating MC4R variants are the most frequent cause of monogenic obesity. In general, obesity is a growing problem on a global scale and is of social, medical, and economic relevance. A significant goal is to develop optimized pharmacological tools targeting MC4R without adverse effects. To date, this has not been achieved because of inter alia non-selective ligands across the five functionally different MCR subtypes (MC1-5R). This motivates further investigation of (i) the three-dimensional MC4R structure, (ii) binding mechanisms of various ligands, and (iii) the molecular transfer process of signal transduction, with the aim of understanding how structural features are linked with functional-physiological aspects. Unfortunately, experimentally elucidated structural information is not yet available for the MC receptors, a group of class A G-protein coupled receptors (GPCRs). We, therefore, generated MC4R homology models and complexes with interacting partners to describe approximate structural properties associated with signaling mechanisms. In addition, molecular insights from pathogenic mutations were incorporated to discriminate more precisely their individual malfunction of the signal transfer mechanism.

Obesity: Hypothalamic Regulation of Food Intake

Current estimates suggest that over 1 billion people are overweight and over 300 million people are obese. Weight gain is due to an imbalance between energy expenditure and dietary intake. This review discusses the hypothalamic control of appetite. Nuclei within the hypothalamus integrate peripheral signals such as adiposity and caloric intake to regulate important pathways within the central nervous system controlling food intake to energy expenditure. These pathways involve the orexigenic NPY/AgRP and the anorexigenic POMC/CART neurons the arcuate nucleus (ARC) of the hypothalamus.

High vitamin A intake during pregnancy modifies dopaminergic reward system and decreases preference for sucrose in Wistar rat offspring

High multivitamin (HV) content in gestational diets has long-term metabolic effects in rat offspring. These changes are associated with in utero modifications of gene expression in hypothalamic food intake regulation. However, the role of fat-soluble vitamins in mediating these effects has not been explored. Vitamin A is a plausible candidate due to its role in gene methylation. Vitamin A intake above requirements during pregnancy affects the development of neurocircuitries involved in food intake and reward regulation. Pregnant Wistar rats were fed AIN-93G diets with the following content: recommended multivitamins (1-fold multivitamins: RV), high vitamin A (10-fold vitamin A: HA) or HV with only recommended vitamin A (10-fold multivitamins, 1-fold vitamin A: HVRA). Body weight, food intake and preference, mRNA expression and DNA methylation of hippocampal dopamine-related genes were assessed in male offspring brains at different developmental windows: birth, weaning and 14weeks postweaning. HA offspring had changes in dopamine-related gene expression at all developmental windows and DNA hypermethylation in the dopamine receptor 2 promoter region compared to RV offspring. Furthermore, HA diet lowered sucrose preference but had no effect on body weight and expression of hypothalamic genes. In contrast, HVRA offspring showed only at adulthood changes in expression of hippocampal genes and a modest effect on hypothalamic genes. High vitamin A intake alone in gestational diets has long-lasting programming effects on the dopaminergic system that are further translated into decreased sucrose preference but not food intake.

Withdrawal of dietary phytoestrogens in adult male rats affects hypothalamic regulation of food intake, induces obesity and alters glucose metabolism

The absence of phytoestrogens in the diet during pregnancy has been reported to result in obesity later in adulthood. We investigated whether phytoestrogen withdrawal in adult life could alter the hypothalamic signals that regulate food intake and affect body weight and glucose homeostasis.Male Wistar rats fed from conception to adulthood with a high phytoestrogen diet were submitted to phytoestrogen withdrawal by feeding a low phytoestrogen diet, or a high phytoestrogen–high fat diet. Withdrawal of dietary phytoestrogens increased body weight, adiposity and energy intake through an orexigenic hypothalamic response characterized by upregulation of AGRP and downregulation of POMC. This was associated with elevated leptin and T4, reduced TSH, testosterone and estradiol, and diminished hypothalamic ERα expression, concomitant with alterations in glucose tolerance.Removing dietary phytoestrogens caused manifestations of obesity and diabetes that were more pronounced than those induced by the high phytoestrogen–high fat diet intake.

Role of methyl group vitamins in hypothalamic development of food intake regulation in Wistar rats

High multivitamin diets (HV; 10-fold AIN-93G) fed during pregnancy to Wistar rats produce offspring with increased food intake, obesity, and characteristics of metabolic syndrome. The hypothesis that methyl group vitamins in HV gestational and pup diets modify expression of the obesogenic phenotypes in the offspring through their effects on hypothalamic feeding pathways was tested by 4 studies. In studies 1 and 2, dams were fed the AIN-93G diet with recommended vitamin (RV), HV, high methyl vitamins (10-fold folate, vitamin B12 and vitamin B6) (HMethyl), or HV with normal folate (HVNF) and male offspring were weaned to a high-fat diet for 8 weeks. In studies 3 and 4, dams were fed RV, HV, or high 10-fold folate (HFol), and male offspring were weaned to RV, HV, or HFol diets for 29 weeks. The results were as follows: (i) HV and HMethyl diets increased obesogenic phenotypes and altered hypothalamic regulation of food intake and metabolism concurrent with epigenetic effects on gene expression. (ii) Removing folate additions to the HV diet showed that folate contributes to the obesogenic phenotype in the offspring and epigenetic alterations in the hypothalamus that favour increased food intake. (iii) Matching pup diet vitamin content with that of the HV and HFol diet-fed dams prevented their increased food intake, body weight, and insulin resistance when weaned to the RV diet. (iv) Both HFol gestational and pup diets altered hypothalamic feeding pathways through DNA methylation, showing that epigenetic effects of these vitamins occur not only in utero but also postnatally. In conclusion, methyl group vitamins in HV gestational and pup diets modify expression of the obesogenic phenotypes and hypothalamic food intake regulatory systems in the Wistar rat offspring.

Hypothalamic food intake regulation in a cancer‐cachectic mouse model

BackgroundAppetite is frequently affected in cancer patients leading to anorexia and consequently insufficient food intake. In this study, we report on hypothalamic gene expression profile of a cancer-cachectic mouse model with increased food intake. In this model, mice bearing C26 tumour have an increased food intake subsequently to the loss of body weight. We hypothesise that in this model, appetite-regulating systems in the hypothalamus, which apparently fail in anorexia, are still able to adapt adequately to changes in energy balance. Therefore, studying changes that occur on appetite regulators in the hypothalamus might reveal targets for treatment of cancer-induced eating disorders. By applying transcriptomics, many appetite-regulating systems in the hypothalamus could be taken into account, providing an overview of changes that occur in the hypothalamus during tumour growth.MethodsC26-colon adenocarcinoma cells were subcutaneously inoculated in 6 weeks old male CDF1 mice. Body weight and food intake were measured three times a week. On day 20, hypothalamus was dissected and used for transcriptomics using Affymetrix chips.ResultsFood intake increased significantly in cachectic tumour-bearing mice (TB), synchronously to the loss of body weight. Hypothalamic gene expression of orexigenic neuropeptides NPY and AgRP was higher, whereas expression of anorexigenic genes CCK and POMC were lower in TB compared to controls.In addition, serotonin and dopamine signalling pathways were found to be significantly altered in TB mice. Serotonin levels in brain showed to be lower in TB mice compared to control mice, while dopamine levels did not change. Moreover, serotonin levels inversely correlated with food intake.ConclusionsTranscriptomic analysis of the hypothalamus of cachectic TB mice with an increased food intake showed changes in NPY, AgRP and serotonin signalling. Serotonin levels in the brain showed to correlate with changes in food intake. Further research has to reveal whether targeting these systems will be a good strategy to avoid the development of cancer-induced eating disorders.Electronic supplementary materialThe online version of this article (doi:10.1007/s13539-013-0121-y) contains supplementary material.

Nicotinamide induces male-specific body weight loss in the postnatal period through molecular regulation of the hypothalamus and liver

Molecular mechanisms of body weight control have been discovered recently and much research focuses on the hypothalamic regulation of food intake and the hepatic regulation of glucose utility. We previously reported that postnatal nicotinamide treatment reduced brain dopamine and body weight. To further investigate the differential effects of nicotinamide-mediated body weight loss, nicotinamide (i.p. 100mg/kg) was injected into postnatal and adult mice twice a week for 4 weeks. Interestingly, following nicotinamide treatment, male postnatal mice displayed reduced body weight and spontaneous motor activity. No significant changes were observed in adult and postnatal female mice or adult male mice following nicotinamide treatment. In male postnatal mice, hypothalamic agouti-related peptide (AGRP) and proopiomelanocortin (POMC) levels were increased in the arcuate nucleus following nicotinamide treatment. Neuropeptide Y (NPY) levels were unchanged in both male and female mice. Additionally, nicotinamide-injected male postnatal mice had increased glucose 6-phosphatase (G6Pase) and decreased phosphoenolpyruvate carboxykinase (PEPCK) expression in liver. These results indicate that hypothalamic POMC and hepatic PEPCK are important molecules that mediate nicotinamide-induced weight loss in postnatal male mice.

Ceramide Levels Regulated by Carnitine Palmitoyltransferase 1C Control Dendritic Spine Maturation and Cognition

The brain-specific isoform carnitine palmitoyltransferase 1C (CPT1C) has been implicated in the hypothalamic regulation of food intake and energy homeostasis. Nevertheless, its molecular function is not completely understood, and its role in other brain areas is unknown. We demonstrate that CPT1C is expressed in pyramidal neurons of the hippocampus and is located in the endoplasmic reticulum throughout the neuron, even inside dendritic spines. We used molecular, cellular, and behavioral approaches to determine CPT1C function. First, we analyzed the implication of CPT1C in ceramide metabolism. CPT1C overexpression in primary hippocampal cultured neurons increased ceramide levels, whereas in CPT1C-deficient neurons, ceramide levels were diminished. Correspondingly, CPT1C knock-out (KO) mice showed reduced ceramide levels in the hippocampus. At the cellular level, CPT1C deficiency altered dendritic spine morphology by increasing immature filopodia and reducing mature mushroom and stubby spines. Total protrusion density and spine head area in mature spines were unaffected. Treatment of cultured neurons with exogenous ceramide reverted the KO phenotype, as did ectopic overexpression of CPT1C, indicating that CPT1C regulation of spine maturation is mediated by ceramide. To study the repercussions of the KO phenotype on cognition, we performed the hippocampus-dependent Morris water maze test on mice. Results show that CPT1C deficiency strongly impairs spatial learning. All of these results demonstrate that CPT1C regulates the levels of ceramide in the endoplasmic reticulum of hippocampal neurons, and this is a relevant mechanism for the correct maturation of dendritic spines and for proper spatial learning.

A review of late-stage CNS drug candidates for the treatment of obesity

Obesity is an important causative factor in morbidity, disability and premature death. Increasing levels of obesity will impose enormous health, financial and social burdens on worldwide society unless effective interventions are implemented. For many obese individuals, diet and behavioural modification need to be supplemented by pharmacotherapy. Preclinical research has revealed a greater understanding of the complex nature of the hypothalamic regulation of food intake and has generated a wide range of new molecular targets for the development of drug candidates for obesity treatment. As shown by the clinical results that have been obtained with this next generation of therapies, some approaches, for example, fixed-dose drug combinations, have already demonstrated an ability to deliver levels of efficacy that are not achievable with the current antiobesity drug therapies. The regulatory and marketing landscape for development, registration and commercialisation of novel centrally acting drugs for treatment of obesity and related metabolic disorders has changed substantially in recent years. Now a much greater emphasis is placed on tolerability and safety, as well as efficacy. In this review we briefly describe the therapeutic approaches to tackle obesity that are in late-stage clinical development. We then discuss drugs in late-stage development for the treatment of obesity and also future directions.

Early life overfeeding decreases acylated ghrelin circulating levels and upregulates GHSR1a signaling pathway in white adipose tissue of obese young mice

Ghrelin is a hormone synthesized by the stomach that acts in different tissues via a specific receptor (GHS-R1a), including hypothalamus and adipose tissue. For instance, recent reports have shown that ghrelin has a direct action on hypothalamic regulation of food intake mainly inducing an orexigenic effect. On the other hand, ghrelin also modulates energy stores and expenditure in the adipocytes. This dual action has suggested that this hormone may act as a link between the central nervous system and peripheral mechanisms. Furthermore, concerning nutritional disorders, it has been suggested that obesity may be considered an impairment of the above cited link. Therefore, considering that neonatal overfeeding induces obesity in adulthood by unknown mechanisms, in this study we examined the effects of early life overnutrition on the development of obesity and in particular on adipose tissue ghrelin signaling in young mice. Our data demonstrated that overnutrition during early life induces a significant increase in body weight of young mice, starting at 10days, and this increase in weight persisted until adulthood (90days of age). In these animals, blood glucose, liver weight and visceral fat weight were found higher at 21days when compared to the control group. Acylated ghrelin circulating levels were found lower in the young obese pups. In addition, in white adipose tissue ghrelin receptor (GHS-R1a) expression increased and was associated to positive modulation of content and phosphorylation of proteins involved in cell energy store and use as AKT, PI3K, AMPK, GLUT-4, and CPT1. However, PPARγ content decreased in obese group. Basically, we showed that adipose tissue metabolism is altered in early life acquired obesity and probably due to such modification a new pattern of ghrelin signaling pathway takes place.

Endocrine factors in the hypothalamic regulation of food intake in females: a review of the physiological roles and interactions of ghrelin, leptin, thyroid hormones, oestrogen and insulin

Controlling energy homeostasis involves modulating the desire to eat and regulating energy expenditure. The controlling machinery includes a complex interplay of hormones secreted at various peripheral endocrine endpoints, such as the gastrointestinal tract, the adipose tissue, thyroid gland and thyroid hormone-exporting organs, the ovary and the pancreas, and, last but not least, the brain itself. The peripheral hormones that are the focus of the present review (ghrelin, leptin, thyroid hormones, oestrogen and insulin) play integrated regulatory roles in and provide feedback information on the nutritional and energetic status of the body. As peripheral signals, these hormones modulate central pathways in the brain, including the hypothalamus, to influence food intake, energy expenditure and to maintain energy homeostasis. Since the growth of the literature on the role of various hormones in the regulation of energy homeostasis shows a remarkable and dynamic expansion, it is now becoming increasingly difficult to understand the individual and interactive roles of hormonal mechanisms in their true complexity. Therefore, our goal is to review, in the context of general physiology, the roles of the five best-known peripheral trophic hormones (ghrelin, leptin, thyroid hormones, oestrogen and insulin, respectively) and discuss their interactions in the hypothalamic regulation of food intake.

Hypothalamic regulation of food intake and clinical therapeutic applications

Current estimates suggest that over 1 billion people are overweight and over 300 million people are obese. Weight gain is due to an imbalance between energy expenditure and dietary intake. This review discusses the hypothalamic control of appetite and highlights key developments in research that have furthered our understanding of the complex pathways involved. Nuclei within the hypothalamus integrate peripheral signals such as adiposity and caloric intake to regulate important pathways within the central nervous system controlling food intake and energy expenditure. Firmly established pathways involve the orexigenic NPY/AgRP and the anorexigenic POMC/CART neurons in the arcuate nucleus (ARC) of the hypothalamus. These project from the ARC to other important hypothalamic nuclei, including the paraventricular, dorsomedial, ventromedial and lateral hypothalamic nuclei. In addition there are many projections to and from the brainstem, cortical areas and reward pathways, which modulate food intake.

Localization of phospho-tyrosine489-β-adducin immunoreactivity in the hypothalamic tanycytes and its involvement in energy homeostasis

β-Adducin is a cytoskeletal protein that interacts with the actin filaments to suppress actin polymerization and facilitate actin-spectrin binding. We have previously shown that β-adducin is phosphorylated by Fyn at tyrosine489 in the rat brain and bound to its Src-homology 2 domain. In the present study, we examined the immunohistochemical localization of the tyrosine489-phosphorylated form of β-adducin (pY489-β-adducin) in the rat brain. Among brain regions, highest immunoreactivity was located in the hypothalamic tanycytes that are of glial origin lining around the third cerebral ventricle. Their immunoreactive processes extended into the arcuate nucleus, ventromedial hypothalamus and the median eminence. In addition, the pY489-β-adducin immunoreactivity in the tanycytes was enhanced after fasting for 36–48 h, being associated with a morphological change of the DARPP-32-immunoreactivity. Intraperitoneal injection of 2-deoxy- d-glucose also enhances pY489-β-adducin immunoreactivity in the tanycytes, along with increased food intake. These results suggest that tyrosine phosphorylation of β-adducin in the tanycytes is involved in hypothalamic regulation of food intake and energy homeostasis.

Deficiency of glucose-dependent insulinotropic polypeptide receptor prevents ovariectomy-induced obesity in mice

Menopause and premature gonadal steroid deficiency are associated with increases in fat mass and body weight. Ovariectomized (OVX) mice also show reduced locomotor activity. Glucose-dependent-insulinotropic-polypeptide (GIP) is known to play an important role both in fat metabolism and locomotor activity. Therefore, we hypothesized that the effects of estrogen on the regulation of body weight, fat mass, and spontaneous physical activity could be mediated in part by GIP signaling. To test this hypothesis, C57BL/6 mice and GIP-receptor knockout mice (Gipr(-/-)) were exposed to OVX or sham operation (n = 10 per group). The effects on body composition, markers of insulin resistance, energy expenditure, locomotor activity, and expression of hypothalamic anorexigenic and orexigenic factors were investigated over 26 wk in all four groups of mice. OVX wild-type mice developed obesity, increased fat mass, and elevated markers of insulin resistance as expected. This was completely prevented in OVX Gipr(-/-) animals, even though their energy expenditure and spontaneous locomotor activity levels did not significantly differ from those of OVX wild-type mice. Cumulative food intake in OVX Gipr(-/-) animals was significantly reduced and associated with significantly lower hypothalamic mRNA expression of the orexigenic neuropeptide Y (NPY) but not of cocaine-amphetamine-related transcript (CART), melanocortin receptors (MCR-3 and MCR-4), or thyrotropin-releasing hormone (TRH). GIP receptors thus interact with estrogens in the hypothalamic regulation of food intake in mice, and their blockade may carry promising potential for the prevention of obesity in gonadal steroid deficiency.

Antipsychotic drug-induced weight gain mediated by histamine H1receptor-linked activation of hypothalamic AMP-kinase

The atypical antipsychotic drugs (AAPDs) have markedly enhanced the treatment of schizophrenias but their use has been hindered by the major weight gain elicited by some AAPDs. We report that orexigenic AAPDs potently and selectively activate hypothalamic AMP-kinase, an action abolished in mice with deletion of histamine H1 receptors. These findings may afford a means of developing more effective therapeutic agents and provide insight into the hypothalamic regulation of food intake.

C75, a Fatty Acid Synthase (FAS) Inhibitor

Recent data has demonstrated that fatty acid metabolism plays a critical role in the hypothalamic regulation of food intake and the evidence is as follows. Circulating long chain fatty acids act as nutrient surplus signals in the hypothalamus. On addition, fatty acid synthesis pathway enzymes, such as fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) and its upstream regulator, AMP-activated protein kinase (AMPK) are regulated by nutritional and hormonal stimuli. Very importantly, current evidence also indicates that fatty acid metabolism pathway may be a potential target for obesity treatment. In this sense, it has been demonstrated that pharmacological inhibition of FAS results in profound decrease in food intake and body weight in rodents. These anorectic actions are mediated by the modulation of hypothalamic neuropeptide systems, through a malonyl-CoA dependent mechanism. In this review, we recapitulate what is known about hypothalamic fatty acid metabolism and the regulation of feeding, with particular interest in a specific FAS inhibitor, C75, which has been recently patented as a potential drug for adipose mass reduction. Keywords: AMP-activated protein kinase (AMPK), C75, cerulenin, fatty acid synthase (FAS), FAS inhibitors, food intake, hypothalamus, lipid sensing, tamoxifen