Serotonergic drugs : effects on appetite expression and use for the treatment of obesity

Tesofensine, a novel antiobesity drug, silences GABAergic hypothalamic neurons

Obesity is a major global health epidemic that has adverse effects on both the people affected as well as the cost to society. Several anti-obesity drugs that target GLP-1 receptors have recently come to the market. Here, we describe the effects of tesofensine, a novel anti-obesity drug that acts as a triple monoamine neurotransmitter reuptake inhibitor. Using various techniques, we investigated its effects on weight loss and underlying neuronal mechanisms in mice and rats. These include behavioral tasks, DeepLabCut videotaped analysis, electrophysiological ensemble recordings, optogenetic activation, and chemogenetic silencing of GABAergic neurons in the Lateral Hypothalamus (LH). We found that tesofensine induces a greater weight loss in obese rats than lean rats, while differentially modulating the neuronal ensembles and population activity in LH. In Vgat-ChR2 and Vgat-IRES-cre transgenic mice, we found for the first time that tesofensine inhibited a subset of LH GABAergic neurons, reducing their ability to promote feeding behavior, and chemogenetically silencing them enhanced tesofensine's food-suppressing effects. Unlike phentermine, a dopaminergic appetite suppressant, tesofensine causes few, if any, head-weaving stereotypy at therapeutic doses. Most importantly, we found that tesofensine prolonged the weight loss induced by 5-HTP, a serotonin precursor, and blocked the body weight rebound that often occurs after weight loss. Behavioral studies on rats with the tastant sucrose indicated that tesofensine's appetite suppressant effects are independent of taste aversion and do not directly affect the perception of sweetness or palatability of sucrose. In summary, our data provide new insights into the effects of tesofensine on weight loss and the underlying neuronal mechanisms, suggesting that tesofensine may be an effective treatment for obesity and that it may be a valuable adjunct to other appetite suppressants to prevent body weight rebound.

Effects of bariatric surgery and dietary interventions for obesity on brain neurotransmitter systems and metabolism: A systematic review of positron emission tomography (PET) and single-photon emission computed tomography (SPECT) studies

This systematic review collates studies of dietary or bariatric surgery interventions for obesity using positron emission tomography and single-photon emission computed tomography. Of 604 publications identified, 22 met inclusion criteria. Twelve studies assessed bariatric surgery (seven gastric bypass, five gastric bypass/sleeve gastrectomy), and ten dietary interventions (six low-calorie diet, three very low-calorie diet, one prolonged fasting). Thirteen studies examined neurotransmitter systems (six used tracers for dopamine DRD2/3 receptors: two each for 11 C-raclopride, 18 F-fallypride, 123 I-IBZM; one for dopamine transporter, 123 I-FP-CIT; one used tracer for serotonin 5-HT2A receptor, 18 F-altanserin; two used tracers for serotonin transporter, 11 C-DASB or 123 I-FP-CIT; two used tracer for μ-opioid receptor, 11 C-carfentanil; one used tracer for noradrenaline transporter, 11 C-MRB); seven studies assessed glucose uptake using 18 F-fluorodeoxyglucose; four studies assessed regional cerebral blood flow using 15 O-H2 O (one study also used arterial spin labeling); and two studies measured fatty acid uptake using 18 F-FTHA and one using 11 C-palmitate. The review summarizes findings and correlations with clinical outcomes, eating behavior, and mechanistic mediators. The small number of studies using each tracer and intervention, lack of dietary intervention control groups in any surgical studies, heterogeneity in time since intervention and degree of weight loss, and small sample sizes hindered the drawing of robust conclusions across studies.

Unraveling the serotonin saga: from discovery to weight regulation and beyond - a comprehensive scientific review

The prevalence of obesity is rapidly increasing worldwide, while the development of effective obesity therapies lags behind. Although new therapeutic targets to alleviate obesity are identified every day, and drug efficacy is improving, adverse side effects and increased health risks remain serious issues facing the weight-loss industry. Serotonin, also known as 5-HT, has been extensively studied in relation to appetite reduction and weight loss. As a result, dozens of upstream and downstream neural targets of 5-HT have been identified, revealing a multitude of neural circuits involved in mediating the anorexigenic effect of 5-HT. Despite the rise and fall of several 5-HT therapeutics in recent decades, the future of 5-HT as a therapeutic target for weight-loss therapy looks promising. This review focuses on the history of serotonin, the state of current central serotonin research, previous serotonergic therapies, and the future of serotonin for treating individuals with obesity.

Atomoxetine and Fluoxetine Activate AMPK-ACC-CPT1 Pathway in Human SH-SY5Y and U-87 MG Cells

OBJECTIVE

Atomoxetine and fluoxetine are psychopharmacologic agents associated with loss of appetite and weight. Adenosine monophosphate-activated protein kinase (AMPK) is the cellular energy sensor that regulate metabolism and energy, being activated by fasting and inhibited by feeding in the hypothalamus.

METHODS

Human brain cell lines (SH-SY5Y and U-87 MG cells) were used to study the outcome of atomoxetine and fluoxetine treatment in the activity of AMPK-acetyl-CoA carboxylase (ACC)- carnitine palmitoyl transferase 1 (CPT1) pathway and upstream regulation by calcium/calmodulin-dependent kinase kinase β (CaMKKβ) using immunoblotting and CPT1 enzymatic activity measures.

RESULTS

Phosphorylation of AMPK and ACC increased significantly after atomoxetine and fluoxetine treatment in the first 30-60 minutes of treatment in the two cell lines. Activation of AMPK and inhibition of ACC was associated with an increase by 5-fold of mitochondrial CPT1 activity. Although the neuronal isoform CPT1C could be detected by immunoblotting, activity was not changed by the drug treatments. In addition, the increase in phospho-AMPK and phospho-ACC expression induced by atomoxetine was abolished by treatment with STO-609, a CaMKKβ inhibitor, indicating that AMPK-ACC-CPT1 pathway is activated through CaMKKβ phosphorylation.

CONCLUSION

These findings indicate that at the cellular level atomoxetine and fluoxetine treatments may activate AMPK-ACC-CPT1 pathways through CaMKKβ in human SH-SY5Y and U-87 MG cells.

The complex clinical response to selective serotonin reuptake inhibitors in depression: a network perspective

The clinical response to selective serotonin reuptake inhibitors (SSRIs) in depression takes weeks to be fully developed and is still not entirely understood. This study aimed to determine the direct and indirect effects of SSRIs relative to a placebo control condition on clinical symptoms of depression. We included data of 8262 adult patients with major depression participating in 28 industry-sponsored US Food and Drug Administration (FDA) registered trials on the efficacy of SSRIs. Clinical symptoms of depression were assessed by the 17 separate items of the Hamilton Depression Rating Scale (HDRS) after 1, 2, 3, 4 and 6 weeks of treatment. Network estimation techniques showed that SSRIs had quick and strong direct effects on the two affective symptoms, i.e., depressed mood and psychic anxiety; direct effects on other symptoms were weak or absent. Substantial indirect effects were found for all four cognitive symptoms, which showed larger reductions in the SSRI condition but mainly in patients reporting larger reductions in depressed mood. Smaller indirect effects were found for two arousal/somatic symptoms via the direct effect on psychic anxiety. Both direct and indirect effects on sleep problems and most arousal/somatic symptoms were weak or absent. In conclusion, our study revealed that SSRIs primarily caused reductions in affective symptoms, which were related to reductions in mainly cognitive symptoms and some specific arousal/somatic symptoms. The results can contribute to disclosing the mechanisms of action of SSRIs, and has the potential to facilitate early detection of responders and non-responders in clinical practice.

Metabolic and Molecular Response to High-Fat Diet Differs between Rats with Constitutionally High and Low Serotonin Tone

Maintaining energy balance is a complex physiological function whose dysregulation can lead to obesity and associated metabolic disorders. The bioamine serotonin (5HT) is an important regulator of energy homeostasis, with its central and peripheral pools influencing energy status in opposing ways. Using sublines of rats with constitutionally increased (high-5HT) or decreased (low-5HT) whole-body 5HT tone, we have previously shown that under standard diet constitutionally higher 5HT activity is associated with increased body weight, adiposity, and impaired glucose homeostasis. Here, we investigated the response of 5HT sublines to an obesogenic diet. Consistent with previous findings, high-5HT animals fed a standard diet had poorer metabolic health. However, in response to a high-fat diet, only low-5HT animals increased body weight and insulin resistance. They also showed more pronounced changes in blood metabolic parameters and the expression of various metabolic genes in hypothalamus and adipose tissue. On the other hand, high-5HT animals appeared to be protected from major metabolic disturbances of the obesogenic diet. The results suggest that constitutionally low 5HT activity is associated with higher susceptibility to harmful effects of a high-energy diet. High-5HT subline, which developed less adverse metabolic outcomes on hypercaloric diets, may prove useful in understanding metabolically healthy obesity in humans.

Association of obesity with headache among US children and adolescents: Evidence from NHANES 1999-2004

Background

Children and adolescents increasingly commonly suffer from obesity and headache. It has been confirmed that there is an association between obesity and headache in adults; however, evidence of such an association in paediatric populations is still controversial. Therefore, this study examined the relationship between obesity and headache among children and adolescents in the US.

Methods

The cross-sectional data of 3948 participants were obtained from the National Health and Nutrition Examination Survey 1999-2004. Weighted logistic regression models were applied to investigate the association between obesity and headache. Subgroup analysis stratified by sex and age was performed to explore the potential difference in the association of paediatric obesity with headache. The performance of paediatric obesity on headache was assessed by receiver operating characteristic (ROC) curve.

Results

The present study involved 3948 participants, of whom 713 (18.1%) had headache. Compared to those without headache, participants with headache tended to be girls and adolescents, have less calcium intake, and have higher levels of body mass index (BMI), C-reactive protein (CRP), serum ferritin and triglycerides (TGs) (all P < 0.05). After fully adjusting for potential confounders, the ORs with 95% CIs for headache were 1.03 (0.58-1.54) and 1.25 (0.68-2.30) for overweight and obese participants in comparison with normal-weight controls, respectively, implying no association of paediatric obesity with headache independent of other potential confounding factors. In addition, although higher odds of headache were noted in girls and adolescents (aged 10-17 years), no statistically significant difference was found across any subgroups. The area under the ROC (AUC) of paediatric obesity on headache was 0.634.

Conclusions

In summary, our study indicated that obesity is not associated with headache among US children and adolescents. Further prospective studies with larger sample size are needed to validate our findings.

Association study of common functional genetic polymorphisms in SLC6A4 (5-HTT) and MAOA genes with obesity in portuguese children

OBJECTIVES

To investigate the association of polymorphisms in SLC6A4 and MAOA genes with obesity indices in children.

MATERIAL AND METHODS

A total of 637 Portuguese children (317 girls; 320 boys) aged 3-11 years-old were genotyped for the SLC6A4 polymorphisms, 5-HTTLPR and STin2, and for a MAOA VNTR. Polymorphisms were analysed by PCR-based methods.

RESULTS

Although non-significant (p = .089), our study revealed the Stin2 10 minor allele with a marked higher frequency in girls with overweight/obesity (0.466) in comparison with controls (0.376). Combining the two SLC6A4 polymorphisms, haplotype S/12 revealed in girls significant or nominally significant protective effects against BMI (β = -0.615; p = .009), BMI Z-score (β = -0.251; p = .006), WC (β = -1.4; p = .02) and WHtR (β = -0.008; p = .04).

CONCLUSIONS

We found some evidences for the role of SLC6A4 gene in measures of childhood obesity, mainly in girls.

Use of Fluoxetine to Reduce Weight in Adults with Overweight or Obesity: Abridged Republication of the Cochrane Systematic Review

INTRODUCTION

Using fluoxetine is one of many weight loss strategies. A serotonin reuptake inhibitor indicated for depression believed to impact weight control by changing an individual's appetite; however, its benefit-risk ratio is unclear. The aim of this review was to assess the efficacy and safety of fluoxetine in reducing weight in adults with overweight or obesity.

METHODS

We searched Cochrane Library, MEDLINE, Embase, and other databases without language restrictions. Cochrane Collaboration tool and GRADE instrument assessed the risk of bias of randomized controlled trials and certainty of their evidence. We conducted random-effects meta-analyses and calculated the risk ratio/mean difference with 95% confidence intervals for the outcomes.

RESULTS

We included 19 trials (2,216 adults) and found that fluoxetine may reduce weight by -2.7 kg (95% CI -4 to -1.4; p < 0.001) and body mass index by -1.1 kg/m2 (95% CI -3.7 to 1.4), compared with placebo; however, it would cause approximately twice as many adverse events, such as dizziness, drowsiness, fatigue, insomnia, or nausea.

CONCLUSIONS

Although low-certainty evidence suggests that off-label fluoxetine may reduce weight, high-certainty research is needed to be conducted in the future to determine its effects exclusively as well as whether it is useful when combined with other agents. This article is based on a Cochrane Review published in the Cochrane Database of Systematic Reviews 2019, Issue 10, DOI: 10.1002/14651858.CD011688.pub2. Cochrane Reviews are regularly updated as new evidence emerges, and in response to feedback, it should be consulted for the most recent version of the review.

Prospects for new drugs to treat binge-eating disorder: Insights from psychopathology and neuropharmacology

BACKGROUND

Binge-eating disorder (BED) is a common psychiatric condition with adverse psychological and metabolic consequences. Lisdexamfetamine (LDX) is the only approved BED drug treatment. New drugs to treat BED are urgently needed.

METHODS

A comprehensive review of published psychopathological, pharmacological and clinical findings.

RESULTS

The evidence supports the hypothesis that BED is an impulse control disorder with similarities to ADHD, including responsiveness to catecholaminergic drugs, for example LDX and dasotraline. The target product profile (TPP) of the ideal BED drug combines treating the psychopathological drivers of the disorder with an independent weight-loss effect. Drugs with proven efficacy in BED have a common pharmacology; they potentiate central noradrenergic and dopaminergic neurotransmission. Because of the overlap between pharmacotherapy in attention deficit hyperactivity disorder (ADHD) and BED, drug-candidates from diverse pharmacological classes, which have already failed in ADHD would also be predicted to fail if tested in BED. The failure in BED trials of drugs with diverse pharmacological mechanisms indicates many possible avenues for drug discovery can probably be discounted.

CONCLUSIONS

(1) The efficacy of drugs for BED is dependent on reducing its core psychopathologies of impulsivity, compulsivity and perseveration and by increasing cognitive control of eating. (2) The analysis revealed a large number of pharmacological mechanisms are unlikely to be productive in the search for effective new BED drugs. (3) The most promising areas for new treatments for BED are drugs, which augment noradrenergic and dopaminergic neurotransmission and/or those which are effective in ADHD.

A retrospective analysis of the "Neverending Trip" after administration of a potent full agonist of 5-HT2A receptor - 25I-NBOMe

BACKGROUND

5-HT2A receptor (e.g. 25I-NBOMe) agonists not only pose risks of acute intoxication but also long-term effects and significant adverse reactions, e.g. hallucinogen persisting perception disorder (HPPD), derealization, and depersonalization.

AIMS

We evaluated the risk associated with single and repeated use of 25I-NBOMe. We aimed to identify factors that may increase the risk of HPPD, increase its severity and determine the time when the first symptoms appear. Herein, we report the first extensive evaluation of 25I-NBOMe-induced HPPD.

METHOD

We assessed all reports (58) collected by The Pomeranian Pharmacovigilance Centre (PPC) from 2013 to 2020.

RESULTS

The study included a total of 58 reports of adverse reactions caused by 25I-NBOMe. In the case of 15 reports (in patients aged 19-26 years), symptoms persisted many months after the discontinuation of 25I-NBOMe. The most common were: pseudohallucinations, bizarre delusions, derealizations and in some cases development or worsening of depression has been diagnosed. HPPD-like symptoms were most common in patients who took the drug regularly (i.e., several times a month). The risk of HPPD-like symptoms is higher in patients who have severe visual pseudohallucinations, severe bizarre delusions, derealization and/or depersonalization onset immediately after taking the drug. Recurrence of HPPD symptoms may be provoked by many factors, however, there is some cases there is no apparent reason. HPPD after 25I-NBOMe use can last from 2 months up to 2 years. In some patients, pharmacological treatment was necessary due to 25I-NBOMe-induced HPPD and depression.

CONCLUSIONS

The study showed long-lasting effects after 25I-NBOMe administration and allowed for the determination of HPPD risk factors.

Orexin, serotonin, and energy balance

The lateral hypothalamus is critical for the control of ingestive behavior and spontaneous physical activity (SPA), as lesion or stimulation of this region alters these behaviors. Evidence points to lateral hypothalamic orexin neurons as modulators of feeding and SPA. These neurons affect a broad range of systems, and project to multiple brain regions such as the dorsal raphe nucleus, which contains serotoninergic neurons (DRN) important to energy homeostasis. Physical activity is comprised of intentional exercise and SPA. These are opposite ends of a continuum of physical activity intensity and structure. Non‐goal‐oriented behaviors, such as fidgeting, standing, and ambulating, constitute SPA in humans, and reflect a propensity for activity separate from intentional activity, such as high‐intensity voluntary exercise. In animals, SPA is activity not influenced by rewards such as food or a running wheel. Spontaneous physical activity in humans and animals burns calories and could theoretically be manipulated pharmacologically to expend calories and protect against obesity. The DRN neurons receive orexin inputs, and project heavily onto cortical and subcortical areas involved in movement, feeding and energy expenditure (EE). This review discusses the function of hypothalamic orexin in energy‐homeostasis, the interaction with DRN serotonin neurons, and the role of this orexin‐serotonin axis in regulating food intake, SPA, and EE. In addition, we discuss possible brain areas involved in orexin–serotonin cross‐talk; the role of serotonin receptors, transporters and uptake‐inhibitors in the pathogenesis and treatment of obesity; animal models of obesity with impaired serotonin‐function; single‐nucleotide polymorphisms in the serotonin system and obesity; and future directions in the orexin–serotonin field.

This article is categorized under:

Metabolic Diseases > Molecular and Cellular Physiology

What pharmacological interventions are effective in binge-eating disorder? Insights from a critical evaluation of the evidence from clinical trials

Binge-eating disorder (BED) is the commonest eating disorder and an important causal factor in obesity. Lisdexamfetamine is the only approved pharmacological treatment. Many drugs have been clinically evaluated and several were described as potentially promising treatments. A comprehensive reassessment of the evidence from these clinical trials has been performed. The questions to be answered were: (1) Does the evidence support claims of efficacy? (2) What pharmacological mechanisms show promise for developing new BED drugs? (3) What are the clinical implications for treating BED? PubMed and internal database searches identified every available published drug trial in BED. The trials and their results were summarised and reviewed to re-evaluate the evidence. Factors taken into consideration included psychiatric diagnosis, primary endpoint, secondary outcome measures, trial size, blinding and controls, drop-out rates, placebo response rates and weight-loss. Drugs were classified according to their pharmacology and therapeutic indication to determine which mechanisms were effective and to provide insights into the psychopathology of BED. For most drugs, robust evidence of efficacy in BED is insubstantial or absent. Some catecholaminergic drugs developed for ADHD are also effective in BED; other pharmacological mechanisms are weakly efficacious at best. Reducing BED severity has little impact on weight. Conversely, weight-loss from anti-obesity therapy is ineffective in ameliorating the psychopathological drivers of BED. (1) BED is a psychiatric not a metabolic disorder. (2) Weight-loss drugs are generally ineffective in BED. (3) Efficacy in BED is restricted to powerful catecholaminergic drugs. (4) Drugs acting via noradrenaline, 5-HT, GABA, carbonic anhydrase inhibition, opioid receptors and various ion channels are generally minimally effective at best. (5) Efficacy in BED is dependent on treating its core psychopathology; reducing impulsivity and compulsivity and increasing cognitive restraint over eating. (6) Obese subjects with BED may benefit from separate treatments for these two disorders.

Association between Different Types of Edible Oils and Anthropometric Indices Mood, and Appetite among Women

INTRODUCTION

The objective of this study was to evaluate the relationship between consumption of dietary oils and anthropometric indices, mood, and appetite among women staff of Tehran University of Medical Sciences.

METHODS

A cross-sectional study design was used, and 245 women staff of Tehran University of Medical Sciences participated. A 168-item food frequency questionnaire was used to evaluate dietary and nutrient intake. The association between liquid vegetable oils, hydrogenated vegetable oil, and animal fat intake and anthropometric indices, appetite, and mood was evaluated. The Profile of Mood States (POMS) questionnaire was used to assess mood. A Visual Analogue Scale (VAS) was used to evaluate appetite status. The tape measure was used to measure the waist circumference and height. SPSS was used to compute body mass index (BMI) and waist-to-height ratio (WHtR).

RESULTS

In the present study, sunflower and frying oil were the most consumed liquid oils (n = 135/245 participants). Participants with a moderate intake of MUFA had greater odds ratio (OR: 3.47; 95% CI: 1.20-10.7; P trend = 0.025) of a high appetite compared to those with a low intake of MUFA. However, the study found no evidence of an association between consumption of edible oils (vegetable oils, animal fat oils, and other fatty acid sources) and mood, anthropometric indices, or appetite.

CONCLUSIONS

In the current research, we noticed a significant connection between moderate intake of MUFA and a large appetite and no association between consumption of edible oils and other outcomes. In conclusion, a balanced diet low in fast meals, processed foods, cakes, cookies, and sweets is suggested to limit the consumption of artificial trans-fatty acids.

Role of Nociceptin/Orphanin FQ-NOP Receptor System in the Regulation of Stress-Related Disorders

Nociceptin/orphanin FQ (N/OFQ) is a 17-residue neuropeptide that binds the nociceptin opioid-like receptor (NOP). N/OFQ exhibits nucleotidic and aminoacidics sequence homology with the precursors of other opioid neuropeptides but it does not activate either MOP, KOP or DOP receptors. Furthermore, opioid neuropeptides do not activate the NOP receptor. Generally, activation of N/OFQ system exerts anti-opioids effects, for instance toward opioid-induced reward and analgesia. The NOP receptor is widely expressed throughout the brain, whereas N/OFQ localization is confined to brain nuclei that are involved in stress response such as amygdala, BNST and hypothalamus. Decades of studies have delineated the biological role of this system demonstrating its involvement in significant physiological processes such as pain, learning and memory, anxiety, depression, feeding, drug and alcohol dependence. This review discusses the role of this peptidergic system in the modulation of stress and stress-associated psychiatric disorders in particular drug addiction, mood, anxiety and food-related associated-disorders. Emerging preclinical evidence suggests that both NOP agonists and antagonists may represent a effective therapeutic approaches for substances use disorder. Moreover, the current literature suggests that NOP antagonists can be useful to treat depression and feeding-related diseases, such as obesity and binge eating behavior, whereas the activation of NOP receptor by agonists could be a promising tool for anxiety.

Suppression of Energy Intake by Intragastric l-Tryptophan in Lean and Obese Men: Relations with Appetite Perceptions and Circulating Cholecystokinin and Tryptophan

BACKGROUND

l-Tryptophan reduces energy intake in healthy men. The underlying mechanisms, including appetite, plasma cholecystokinin (CCK), tryptophan (Trp), and the ratio of Trp to large neutral amino acids (Trp:LNAAs ratio), and whether responses differ in lean and obese individuals, are uncertain.

OBJECTIVES

We evaluated the effects of intragastric Trp on energy intake (primary outcome) and their potential mechanisms, pre- and postmeal, in lean men and those with obesity.

METHODS

Twelve lean men [mean ± SD age: 30 ± 3 y; BMI (in kg/m2): 23 ± 1] and 13 men with obesity (mean ± SD age: 31 ± 3 y; BMI: 33 ± 1) received, on 3 separate occasions, in double-blind, randomized order, 3 g ("Trp-3") or 1.5 g ("Trp-1.5") Trp, or control ("C"), intragastrically, 30 min before a buffet-meal. Energy intake from the buffet-meal, hunger, fullness, and plasma CCK and amino acid concentrations were measured in response to Trp alone and for 2 h postmeal. Data were analyzed using maximum likelihood mixed-effects models, with treatment, group, and treatment-by-group interaction as fixed effects.

RESULTS

Trp alone increased plasma CCK, Trp, and the Trp:LNAAs ratio (all P < 0.001), with no difference between groups. Trp suppressed energy intake (P < 0.001), with no difference between groups (lean, C: 1085 ± 102 kcal, Trp-1.5: 1009 ± 92 kcal, Trp-3: 868 ± 104 kcal; obese, C: 1249 ± 98 kcal, Trp-1.5: 1217 ± 90 kcal, Trp-3: 1012 ± 100 kcal). Postmeal, fullness was greater after Trp-3 than after C and Trp-1.5 (all P < 0.05), and in men with obesity than in lean men (P < 0.05). Plasma Trp and the Trp:LNAAs ratio were greater after Trp-3 and Trp-1.5 than after C (all P < 0.001), and tended to be less in men with obesity than in the lean (P = 0.07) (Trp:LNAAs ratio: lean, C: 1.5 ± 0.2, Trp-1.5: 6.9 ± 0.7, Trp-3: 10.7 ± 1.4; obese, C: 1.4 ± 0.1, Trp-1.5: 4.6 ± 0.7, Trp-3: 7.8 ± 1.3). There were inverse correlations of energy intake with plasma Trp and the Trp:LNAAs ratio in both groups (lean, both r = -0.50, P < 0.01; obese, both r = -0.40, P < 0.05).

CONCLUSIONS

Intragastric Trp has potent energy intake-suppressant effects, in both lean men and those with obesity, apparently related to the Trp:LNAAs ratio.

Branched chain amino acids-friend or foe in the control of energy substrate turnover and insulin sensitivity?

Branched chain amino acids (BCAA) and their derivatives are bioactive molecules with pleiotropic functions in the human body. Elevated fasting blood BCAA concentrations are considered as a metabolic hallmark of obesity, insulin resistance, dyslipidaemia, nonalcoholic fatty liver disease, type 2 diabetes and cardiovascular disease. However, since increased BCAA amount is observed both in metabolically healthy and obese subjects, a question whether BCAA are mechanistic drivers of insulin resistance and its morbidities or only markers of metabolic dysregulation, still remains open. The beneficial effects of BCAA on body weight and composition, aerobic capacity, insulin secretion and sensitivity demand high catabolic potential toward amino acids and/or adequate BCAA intake. On the opposite, BCAA-related inhibition of lipogenesis and lipolysis enhancement may preclude impairment in insulin sensitivity. Thereby, the following review addresses various strategies pertaining to the modulation of BCAA catabolism and the possible roles of BCAA in energy homeostasis. We also aim to elucidate mechanisms behind the heterogeneity of ramifications associated with BCAA modulation.

The serotonin 2C receptor agonist lorcaserin, alone and in combination with the opioid receptor antagonist naltrexone, attenuates binge-like ethanol drinking

The serotonin (5-HT) system has been implicated in the pathophysiology of alcohol (ethanol; EtOH) use disorders. Lorcaserin, a 5-HT_2C receptor agonist, attenuates drug self-administration in animal models. We investigated the effects of lorcaserin on EtOH intake using the drinking-in-the-dark (DID) procedure, an animal model of binge-like drinking. We compared the effects of lorcaserin to those of the Food and Drug Administration (FDA)-approved drug naltrexone and examined the effects of combining lorcaserin and naltrexone. To examine whether effects were specific for EtOH, we examined the effects of lorcaserin and naltrexone, administered alone and in combination, on saccharin intake. Adult male C57BL/6J mice received EtOH access (20% v/v) for 2 h in the home-cage during the first 3 days of the DID procedure, beginning 3 h into the dark cycle. On day 4, mice were injected with lorcaserin, naltrexone, or a combination of lorcaserin and naltrexone prior to a 4-h EtOH access. Intake was measured at 2 and 4 h. Lorcaserin reduced EtOH intake in a dose-dependent fashion over the 2- and 4-h measurement periods. Naltrexone also reduced EtOH intake when administered alone, with dose-dependent effects being more pronounced over 2 h rather than the full 4-h session. Combining lorcaserin and naltrexone reduced binge-like EtOH drinking to a greater extent than either drug alone. A similar pattern of results was obtained for saccharin intake. These results suggest that lorcaserin and naltrexone can have additive effects on binge-like EtOH drinking. They also support continued research into the therapeutic potential of lorcaserin for alcohol use disorders.

Effect of Obesity on the Expression of Nutrient Receptors and Satiety Hormones in the Human Colon

Background: Receptors located on enteroendocrine cells (EECs) of the colon can detect nutrients in the lumen. These receptors regulate appetite through a variety of mechanisms, including hormonal and neuronal signals. We assessed the effect of obesity on the expression of these G-protein coupled receptors (GPCRs) and hormones at both mRNA and protein level. Methods: qPCR and immunohistochemistry were used to examine colonic tissue from cohorts of patients from the Netherlands (proximal and sigmoid tissue) and the United Kingdom (tissue from across the colon) and patients were grouped by body mass index (BMI) value (BMI < 25 and BMI ≥ 25). Results: The mRNA expression of the hormones/signaling molecules serotonin, glucagon, peptide YY (PYY), CCK and somatostatin were not significantly different between BMI groups. GPR40 mRNA expression was significantly increased in sigmoid colon samples in the BMI ≥ 25 group, but not proximal colon. GPR41, GPR109a, GPR43, GPR120, GPRC6A, and CaSR mRNA expression were unaltered between low and high BMI. At the protein level, serotonin and PYY containing cell numbers were similar in high and low BMI groups. Enterochromaffin cells (EC) showed high degree of co-expression with amino acid sensing receptor, CaSR while co-expression with PYY containing L-cells was limited, regardless of BMI. Conclusions: While expression of medium/long chain fatty acid receptor GPR40 was increased in the sigmoid colon of the high BMI group, expression of other nutrient sensing GPCRs, and expression profiles of EECs involved in peripheral mechanisms of appetite regulation were unchanged. Collectively, these data suggest that in human colonic tissue, EEC and nutrient-sensing receptor expression profiles are not affected despite changes to BMI.

International Union of Basic and Clinical Pharmacology. CX. Classification of Receptors for 5-hydroxytryptamine; Pharmacology and Function

5-HT receptors expressed throughout the human body are targets for established therapeutics and various drugs in development. Their diversity of structure and function reflects the important role 5-HT receptors play in physiologic and pathophysiological processes. The present review offers a framework for the official receptor nomenclature and a detailed understanding of each of the 14 5-HT receptor subtypes, their roles in the systems of the body, and, where appropriate, the (potential) utility of therapeutics targeting these receptors. SIGNIFICANCE STATEMENT: This review provides a comprehensive account of the classification and function of 5-hydroxytryptamine receptors, including how they are targeted for therapeutic benefit.

A selective serotonin receptor agonist for weight loss and management of menopausal vasomotor symptoms in overweight midlife women: a pilot study

OBJECTIVE

Weight gain and vasomotor symptoms (VMS) are common complaints in midlife women going through the menopause transition. A selective serotonin 2C (5-HT2C) receptor agonist, lorcaserin, which was previously approved by the Food and Drug Administration for weight loss, has unreported observational evidence suggesting improvement in VMS with its use. The goal of this pilot study was to evaluate the efficacy of lorcaserin for weight loss and management of VMS in overweight midlife women.

METHODS

This was a 24-week open label pilot study of 20 overweight midlife women, aged 45-60 years, who were experiencing severe VMS. Participants received lorcaserin at the standard dose of 10 mg twice daily for 12 weeks, followed by 12 weeks of observation off the drug. The primary outcomes were changes in weight and subjectively reported VMS.

RESULTS

At the end of 12 weeks, mean change in weight was -2.4 kg (90% CI, -3.2 to -1.7, P < 0.001). However, the participants returned to the baseline weight at 24 weeks. Participants also reported significant subjective improvement in VMS, with a mean ± SD change in self-reported hot flash frequency from baseline to week 12 of -5.4 ± 3.9 (decrease of 1.4 standard deviations). There was a rapid increase in the frequency of VMS within 2 weeks of discontinuation of lorcaserin with a tendency to approach the baseline frequency of VMS.

CONCLUSIONS

In addition to its weight loss-inducing effect, 5-HT2C receptor modulation may have an additional beneficial effect on VMS in midlife women. A treatment option that targets both weight and VMS in midlife women is attractive. : Video Summary:http://links.lww.com/MENO/A622.

Acute d-fenfluramine, but not fluoxetine decreases sweet intake in BALB/c, C57BL/6 and SWR inbred mouse strains

Dopamine, opioid and muscarinic receptor antagonists differentially reduce sucrose and saccharin intakes across inbred mouse strains. Whereas these systems stimulate sweet intake, serotonin signaling inhibits food intake. The present study examined whether fluoxetine (0.1-10 mg/kg) or d-fenfluramine (0.1-6 mg/kg) differentially inhibited sucrose or saccharin intake in BALB/c, C57BL/6 and SWR mice. Fluoxetine marginally altered sucrose intake in all strains. d-fenfluramine significantly, but quite similarly reduced (ID₄₀) sucrose and saccharin intake in BALB/c (5.7 vs. 5.8 mg/kg), C57BL/6 (4.4 vs. 4.3 mg/kg) and SWR (4.6 vs. 5.6 mg/kg) mice, suggesting serotonin-induced inhibition of orosensory mechanisms in all three inbred mouse strains.

G-Protein-Coupled Receptors in CNS: A Potential Therapeutic Target for Intervention in Neurodegenerative Disorders and Associated Cognitive Deficits

Neurodegenerative diseases are a large group of neurological disorders with diverse etiological and pathological phenomena. However, current therapeutics rely mostly on symptomatic relief while failing to target the underlying disease pathobiology. G-protein-coupled receptors (GPCRs) are one of the most frequently targeted receptors for developing novel therapeutics for central nervous system (CNS) disorders. Many currently available antipsychotic therapeutics also act as either antagonists or agonists of different GPCRs. Therefore, GPCR-based drug development is spreading widely to regulate neurodegeneration and associated cognitive deficits through the modulation of canonical and noncanonical signals. Here, GPCRs’ role in the pathophysiology of different neurodegenerative disease progressions and cognitive deficits has been highlighted, and an emphasis has been placed on the current pharmacological developments with GPCRs to provide an insight into a potential therapeutic target in the treatment of neurodegeneration.

Safety and Efficacy of Weight-Loss Pharmacotherapy in Persons Living with HIV: A Review of the Literature and Potential Drug-Drug Interactions with Antiretroviral Therapy

The prevalence of obesity among persons living with human immunodeficiency virus (HIV) has increased significantly and may be linked to the use of antiretroviral therapy. Although weight-loss medications approved by the U.S. Food and Drug Administration are recommended as an adjunct to diet and exercise to treat obesity in the general population, little is known about the safety and efficacy of these drugs specifically in persons living with HIV. We review the available evidence regarding the effective use of weight-loss pharmacotherapy in persons living with HIV and its potential to interact with antiretroviral therapy. Persons living with HIV are frequently not reported or included in clinical trials for weight-loss medications; however, treatment efficacy is likely similar to the general population. Several important reported or theoretical drug-drug interactions exist between antiobesity pharmacotherapy and antiretroviral therapy. Orlistat is a weight-loss drug available in the United States without a prescription and was linked to HIV viral rebound in several case reports. Clinicians should be aware of the potential for loss of HIV viremia control when certain weight-loss pharmacotherapies are used in combination with antiretrovirals.

Fluoxetine for adults who are overweight or obese

BACKGROUND

Fluoxetine is a serotonin reuptake inhibitor indicated for major depression. It is also thought to affect weight control: this seems to happen through appetite changes resulting in decreased food intake and normalisation of unusual eating behaviours. However, the benefit-risk ratio of this off-label medication is unclear.

OBJECTIVES

To assess the effects of fluoxetine for overweight or obese adults.

SEARCH METHODS

We searched the Cochrane Library, MEDLINE, Embase, LILACS, the ICTRP Search Portal and ClinicalTrials.gov and World Health Organization (WHO) ICTRP Search Portal. The last date of the search was December 2018 for all databases, to which we applied no language restrictions .

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the administration of fluoxetine versus placebo, other anti-obesity agents, non-pharmacological therapy or no treatment in overweight or obese adults without depression, mental illness or abnormal eating patterns.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened abstracts and titles for relevance. Screening for inclusion, data extraction and risk of bias assessment was performed by one author and checked by the second. We assessed trials for the overall certainty of the evidence using the GRADE instrument. For additional information we contacted trial authors by email. We performed random-effects meta-analyses and calculated the risk ratio (RR) with 95% confidence intervals (95% CI) for dichotomous outcomes and the mean difference (MD) with 95% CI for continuous outcomes.

MAIN RESULTS

We identified 1036 records, scrutinized 52 full-text articles and included 19 completed RCTs (one trial is awaiting assessment). A total of 2216 participants entered the trials, 1280 participants were randomly assigned to fluoxetine (60 mg/d, 40 mg/d, 20 mg/d and 10 mg/d) and 936 participants were randomly assigned to various comparison groups (placebo; the anti-obesity agents diethylpropion, fenproporex, mazindol, sibutramine, metformin, fenfluramine, dexfenfluramine, fluvoxamine, 5-hydroxy-tryptophan; no treatment; and omega-3 gel). Within the 19 RCTs there were 56 trial arms. Fifteen trials were parallel RCTs and four were cross-over RCTs. The participants in the included trials were followed up for periods between three weeks and one year. The certainty of the evidence was low or very low: the majority of trials had a high risk of bias in one or more of the risk of bias domains.For our main comparison group - fluoxetine versus placebo - and across all fluoxetine dosages and durations of treatment, the MD was -2.7 kg (95% CI -4 to -1.4; P < 0.001; 10 trials, 956 participants; low-certainty evidence). The 95% prediction interval ranged between -7.1 kg and 1.7 kg. The MD in body mass index (BMI) reduction across all fluoxetine dosages compared with placebo was -1.1 kg/m² (95% CI -3.7 to 1.4; 3 trials, 97 participants; very low certainty evidence). Only nine placebo-controlled trials reported adverse events. A total of 399 out of 627 participants (63.6%) receiving fluoxetine compared with 352 out of 626 participants (56.2%) receiving placebo experienced an adverse event. Random-effects meta-analysis showed an increase in the risk of having at least one adverse event of any type in the fluoxetine groups compared with placebo (RR 1.18, 95% CI 0.99 to 1.42; P = 0.07; 9 trials, 1253 participants; low-certainty evidence). The 95% prediction interval ranged between 0.74 and 1.88. Following fluoxetine treatment the adverse events of dizziness, drowsiness, fatigue, insomnia and nausea were observed approximately twice as often compared to placebo. A total of 15 out of 197 participants (7.6%) receiving fluoxetine compared with 12 out of 196 participants (6.1%) receiving placebo experienced depression. The RR across all fluoxetine doses compared with placebo was 1.20 (95% CI 0.57 to 2.52; P = 0.62; 3 trials, 393 participants; very low certainty evidence). All-cause mortality, health-related quality of life and socioeconomic effects were not reported.The comparisons of fluoxetine with other anti-obesity agents (3 trials, 234 participants), omega-3 gel (1 trial, 48 participants) and no treatment (1 trial, 60 participants) showed inconclusive results (very low certainty evidence).

AUTHORS' CONCLUSIONS

Low-certainty evidence suggests that off-label fluoxetine may decrease weight compared with placebo. However, low-certainty evidence suggests an increase in the risk for dizziness, drowsiness, fatigue, insomnia and nausea following fluoxetine treatment.

CNS-targeting pharmacological interventions for the metabolic syndrome

The metabolic syndrome (MetS) encompasses medical conditions such as obesity, hyperglycemia, high blood pressure, and dyslipidemia that are major drivers for the ever-increasing prevalence of type 2 diabetes, cardiovascular diseases, and certain types of cancer. At the core of clinical strategies against the MetS is weight loss, induced by bariatric surgery, lifestyle changes based on calorie reduction and exercise, or pharmacology. This Review summarizes the past, current, and future efforts of targeting the MetS by pharmacological agents. Major emphasis is given to drugs that target the CNS as a key denominator for obesity and its comorbid sequelae.

Effect of lorcaserin in different age groups: a post hoc analysis of patients from the BLOOM, BLOSSOM and BLOOM-DM studies

INTRODUCTION

The elderly population is projected to be the fastest growing group of individuals with obesity group in the United States. As such, there is merit in examining factors that contribute to healthy aging and weight management. The effects of newer weight loss medications approved after 2013 have been studied but are not often assessed specifically in older persons.

METHODS

This post hoc analysis evaluated the magnitude of weight loss in adults across age quartiles with lorcaserin, a serotonin (5-HT) 2C receptor agonist indicated as an adjunct to a reduced-caloric diet and increased physical activity for chronic weight management. Data from three lorcaserin pivotal phase 3 studies were used in this analysis. Data for patients with overweight/obesity without type 2 diabetes (T2D; BLOOM/BLOSSOM; body mass index [BMI] 27.0-29.9 kg/m2 and ≥1 comorbidity or BMI 30.0-45.0 kg/m2) and patients with overweight/obesity with T2D (BLOOM-DM; BMI 27.0-45.0 kg/m2) were used. Patients were randomized to receive lorcaserin 10 mg twice daily or placebo in addition to diet and exercise for 52 weeks. Age quartiles between the studies differed as the T2D population was on average, 9 years older.

RESULTS

This analysis shows that lorcaserin was associated with improved weight loss relative to placebo regardless of age. Importantly, these results were consistent for patients with and without T2D. Interestingly, the magnitude of weight loss for lorcaserin appeared to increase with increasing age. In patients without T2D, odds of achieving ≥5% and ≥10% reduction in body weight at 52 weeks were significantly higher for patients >36 years. Lorcaserin was well tolerated in all patients across all quartiles including the oldest quartile.

CONCLUSIONS

In summary, this post hoc analysis demonstrates that lorcaserin treatment in patients with and without T2D was safe and effective at reducing weight across all age groups analysed. Weight loss appeared to be greater for older patients; additional analyses are warranted to confirm these findings and to better understand the factors for improved weight loss.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Feeding behaviour, risk-sensitivity and response control: effects of 5-HT2C receptor manipulations

People, like animals, tend to choose the variable option when given the choice between a fixed and variable delay to reward where, in the variable delay condition, some rewards are available immediately (Laura-Jean et al. 2019 Phil. Trans. R. Soc. B 374, 20180141. ( doi:10.1098/rstb.2018.0141 )). This bias has been suggested to reflect evolutionary pressures resulting from food scarcity in the past placing a premium on obtaining food quickly that can win out against the risks of sometimes sustaining longer delays to food. The psychologies mediating this effect may become maladaptive in the developed world where food is readily available contributing, potentially, to overeating and obesity. Here, we report our development of a novel touchscreen task in mice allowing comparisons of the impact of food delay and food magnitude across species. We show that mice exhibit the typical preference, as shown by humans, for variable over fixed delays to rewards but no preference when it comes to fixed versus variable reward amounts and further show that this bias is sensitive to manipulations of the 5-HT2C receptor, a key mediator of feeding and impulse control. We discuss the data in terms of the utility of the task to model the psychologies and underlying brain mechanisms impacting on feeding behaviours. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

The social defeat/overcrowding murine psychosocial stress model results in a pharmacologically reversible body weight gain but not depression - related behaviours

Depression is a highly prevalent psychiatric disorder, yet its etiology is not well understood. The validation of animal models is therefore a critical step towards advancing knowledge about the neurobiology of depression. Psychosocial stress has been promoted as a prospective animal model of depression, however, different protocols exist with variable responses, and further investigations are therefore required. We aimed to characterise the behavioural and body weight responses to the social defeat/overcrowding (SD/OC) model and to explore the effects of the antidepressant fluoxetine and the peroxynitrite scavenger, Cu^II(atsm), therein. Male C57BL/6JArc mice were exposed to a 19 day SD/OC protocol at two levels of aggression, determined by terminating SD bouts after one, or approximately five social defeat postures. This was followed by a battery of behavioural tests including social interaction test (SIT), locomotor activity (LMA), light-dark box test (LDB), saccharin preference test (SPT) and the forced swim test (FST). Mice were dosed daily with vehicle, fluoxetine (20 mg/kg) or Cu^II(atsm) (30 mg/kg) throughout the protocol. SD/OC increased body weight compared to controls, which was abolished by fluoxetine and attenuated by Cu^II(atsm). Weight gain specifically peaked during OC sessions but was not affected by either drug treatment. Fluoxetine reduced the number of defeat postures during fight bouts on some days. SD/OC otherwise failed to elicit depression- or anxiety-like behaviour in the tests measured. These data raise questions over the SD/OC model as an etiological model of depression-related behaviours but highlight the potential of this model for investigations into mechanisms regulating binge eating and weight gain under conditions of chronic social stress.

d-Fenfluramine and lorcaserin inhibit the binge-like feeding induced by μ-opioid receptor stimulation of the nucleus accumbens in the rat

Multiple laboratories have shown that the stimulation of μ-opioid receptors in the nucleus accumbens (NAcc) powerfully increases intake of palatable and high-fat diets. Separate studies have demonstrated that serotonin agonists advance satiety processes, and several serotonin-targeting agents have been prescribed to promote weight loss. However, it is unknown if serotonin signaling can modulate the increased feeding elicited by activation of NAcc μ-opioid receptors. These experiments assessed the effects of systemic treatments with the serotonin agonists d-fenfluramine and lorcaserin on the binge-like feeding induced by μ-opioid receptor stimulation of the NAcc in Sprague-Dawley rats. Consistent with previous reports, stimulation of NAcc μ-opioid receptors (with 0.025 μg/0.5 μl/side DAMGO) significantly increased consumption of high-fat vegetable shortening, and systemic treatment with d-fenfluramine and lorcaserin dose-dependently decreased intake. Interestingly, d-fenfluramine and lorcaserin reversed the binge-like feeding observed following stimulation of NAcc μ-opioid receptors. Both serotonergic drugs also attenuated the increases of ambulation observed following administration of DAMGO in the NAcc. These data demonstrate that serotonergic anorectics, in addition to their known role in advancing satiety processes during normal feeding, can also inhibit the binge-like feeding that is elicited by activation of μ-opioid receptors within the ventral striatum.

Sex differences in the anorexigenic effects of dexfenfluramine and amphetamine in baboons

The anorexigenic effects of intramuscular d-amphetamine HCl (0.06-0.50 mg/kg) and dexfenfluramine HCl (0.25-2.0 mg/kg) were determined in experimentally naïve baboons. A group of 8 adult male baboons was tested prior to a group of 7 adult female baboons. A 120-min session occurred at 9:00 a.m. during which baboons could respond for food pellets. Drug was given 30 min prior to the 9:00 a.m. morning session. Beginning at 11:00 a.m., baboons had a 6-hr multiple-meal session during which they could have up to 4 food pellet meals. Food was not available overnight, but food was available for 90 min upon awakening such that drug effects were evaluated in non-food-deprived animals. Under baseline conditions baboons earned between 30 and 70 pellets during the morning session and another 175-225 pellets during the remainder of the day. Amphetamine and dexfenfluramine produced dose-dependent decreases in food pellet intake during both the morning food session and the later multiple-meal session. Whereas there were minimal sex differences in the effects of dexfenfluramine, many of the amphetamine doses produced greater decreases in pellet intake in males than females. These results are discordant with much of the rodent literature on abuse-related drug effects that generally reports greater effects of amphetamine in females than males. Additional work is needed to replicate the current findings in nonhuman primates. (PsycINFO Database Record

Advances in pediatrics in 2017: current practices and challenges in allergy, endocrinology, gastroenterology, genetics, immunology, infectious diseases, neonatology, nephrology, neurology, pulmonology from the perspective of Italian Journal of Pediatrics

This review provides an overview of a remarkable number of significant studies in pediatrics that have been published over the past year in the Italian Journal of Pediatrics. We have selected information from papers presented in the Journal that deal with allergy, endocrinology, gastroenterology, genetics, immunology, infectious diseases, neonatology, nephrology, neurology, pulmonology. The relevant epidemiologic findings, and developments in prevention, diagnosis and treatment of the last year have been discussed and placed in context. We think that advances achieved in 2017 will help readers to make the future of patients better.

5HT6 Antagonists in the Treatment of Alzheimer's Dementia: Current Progress

Alzheimer’s disease is an important condition with a considerable and unmet disease burden in large need of continued research and more treatment options. The 5HT6 antagonists are a new class of medications to be offered. Because they are pro-cholinergic, these medications are to be used as adjuncts to acetylcholinesterase inhibitors (such as donepezil), further increasing acetylcholine in the central nervous system (CNS). Early trials of the 5HT6 antagonists showed improvements in cognition and activities of daily living when used as adjuncts to current therapies for Alzheimer’s dementia. However, recent phase III trials have failed to show a statistically significant improvement in cognitive function. This article will provide a comprehensive review of 5HT6 antagonists in drug development, including some that have been recently discontinued. We will discuss both the successes and failures of this drug class and provide rationale for their continued research and development.

The Science of Obesity Management: An Endocrine Society Scientific Statement

The prevalence of obesity, measured by body mass index, has risen to unacceptable levels in both men and women in the United States and worldwide with resultant hazardous health implications. Genetic, environmental, and behavioral factors influence the development of obesity, and both the general public and health professionals stigmatize those who suffer from the disease. Obesity is associated with and contributes to a shortened life span, type 2 diabetes mellitus, cardiovascular disease, some cancers, kidney disease, obstructive sleep apnea, gout, osteoarthritis, and hepatobiliary disease, among others. Weight loss reduces all of these diseases in a dose-related manner-the more weight lost, the better the outcome. The phenotype of "medically healthy obesity" appears to be a transient state that progresses over time to an unhealthy phenotype, especially in children and adolescents. Weight loss is best achieved by reducing energy intake and increasing energy expenditure. Programs that are effective for weight loss include peer-reviewed and approved lifestyle modification programs, diets, commercial weight-loss programs, exercise programs, medications, and surgery. Over-the-counter herbal preparations that some patients use to treat obesity have limited, if any, data documenting their efficacy or safety, and there are few regulatory requirements. Weight regain is expected in all patients, especially when treatment is discontinued. When making treatment decisions, clinicians should consider body fat distribution and individual health risks in addition to body mass index.

Pharmacotherapy for obesity in individuals with type 2 diabetes

INTRODUCTION

Type 2 diabetes (T2DM) is associated with significant morbidity and mortality. Obesity is one of the main risk factors for T2DM and its management requires a multidisciplinary approach, which may include pharmacotherapy.

AREAS COVERED

In this paper, data on efficacy, tolerability and safety of FDA-approved pharmacotherapies for obesity (orlistat, phentermine/topiramate extended-release, lorcaserin, bupropion sustained release/naltrexone sustained release and liraglutide) are reviewed, focusing on individuals with type 2 diabetes.

EXPERT OPINION

Obesity is the major pathophysiologic driver of T2DM; conversely 5-10% weight loss leads to significant improvement in glycemic control, lipids and blood pressure. Weight loss maintenance is difficult with lifestyle interventions alone and may require adjunctive therapies. There is good evidence for the efficacy and tolerability of approved anti-obesity pharmacotherapies in individuals with T2DM, with current cardiovascular safety data being most favorable for liraglutide, orlistat and lorcaserin. Given the link between obesity and T2DM, a weight-centric therapeutic approach including use of weight reducing anti-diabetic therapies, and anti-obesity pharmacotherapies is both intuitive and rational to improve glycemic and other metabolic outcomes in patients with T2DM.

Dopamine and μ-opioid receptor dysregulation in the brains of binge-eating female rats - possible relevance in the psychopathology and treatment of binge-eating disorder

Adult, female rats given irregular, limited access to chocolate develop binge-eating behaviour with normal bodyweight and compulsive/perseverative and impulsive behaviours similar to those in binge-eating disorder. We investigated whether (a) dysregulated central nervous system dopaminergic and opioidergic systems are part of the psychopathology of binge-eating and (b) these neurotransmitter systems may mediate the actions of drugs ameliorating binge-eating disorder psychopathology. Binge-eating produced a 39% reduction of striatal D₁ receptors with 22% and 23% reductions in medial and lateral caudate putamen and a 22% increase of striatal μ-opioid receptors. There was no change in D₁ receptor density in nucleus accumbens, medial prefrontal cortex or dorsolateral frontal cortex, striatal D₂ receptors and dopamine reuptake transporter sites, or μ-opioid receptors in frontal cortex. There were no changes in ligand affinities. The concentrations of monoamines, metabolites and estimates of dopamine (dopamine/dihydroxyphenylacetic acid ratio) and serotonin/5-hydroxyindolacetic acid ratio turnover rates were unchanged in striatum and frontal cortex. However, turnover of dopamine and serotonin in the hypothalamus was increased ~20% and ~15%, respectively. Striatal transmission via D₁ receptors is decreased in binge-eating rats while μ-opioid receptor signalling may be increased. These changes are consistent with the attenuation of binge-eating by lisdexamfetamine, which increases catecholaminergic neurotransmission, and nalmefene, a μ-opioid antagonist.

The link between obesity and migraine in childhood: a systematic review

Obesity and headache are two highly prevalent diseases both in adults and children and they are associated with a strong personal and social impact. Many studies suggest that obesity is comorbid with headache in general, and migraine in particular and obesity seems to be a risk factor for migraine progression and for migraine frequency both in adults and in children. Research shows that there are multiple areas of overlap between migraine pathophysiology and the central and peripheral pathways regulating feeding: inflammatory mediators such as the calcitonin gene-related protein (CGRP), neurotransmitters such as serotonin, peptides such as orexin and adipocytokines such as adiponectin (ADP) and leptin could explain the common pathogenesis. In this paper we discussed the association between obesity and migraine through the analysis of the most recent studies in children and we reviewed data from literature in order to assess the association between obesity and headache and to clarify the possible common pathogenic mechanisms.

Biallelic and triallelic approaches of 5-HTTLPR polymorphism are associated with food intake and nutritional status in childhood

BACKGROUND

The 5-HTT gene contains polymorphisms in its promoter region, the insertion/deletion (5-HTTLPR) that creates long (L) or short (S) alleles (biallelic approach) and SNP (rs25531) in L allele (triallelic approach).

OBJECTIVES

The aim of this study is to investigate the association of the 5-HTTLPR and rs25531 polymorphisms, using bi- and triallelic approach, with dietary intake and anthropometric parameters in children followed until 8 years old.

METHODS

The sample were 303 children who were recruited at birth and examined at 1, 3 to 4 and 7 to 8 years old. The polymorphisms were analyzed by polymerase-chain-reaction-based methods.

RESULTS

In the biallelic approach, children with the S/S genotype presented a higher body mass index Z-score in the three developmental stages and higher sum of skinfolds at 3 to 4 and 7 to 8 years old than carriers of the L allele. In the triallelic approach, S/S, Lg/S plus Lg/Lg genotypes were associated with higher energy intake daily at 1 year old and with waist circumference at 3 to 4 years old.

CONCLUSIONS

In the biallelic approach, the 5-HTTLPR polymorphism is associated with food intake, body mass index Z-score and sum of skinfolds in children, reinforcing the role of the serotonin transporter in childhood obesity. Our data indicate that the biallelic approach is more sensible than the triallelic approach for detected associations with food intake and nutritional status in childhood. Identifying susceptibility genes in early life could provide the foundations for interventions in lifestyle to prevent children to become obese adults.

Functional Neuroimaging in Obesity Research

Functional neuroimaging is beginning to yield valuable insights into the neurobiological underpinnings of the effects of obesity on neural circuits. Functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) studies have been used to identify aberrant activation patterns in regions implicated in reward (e.g., striatum, orbitofrontal cortex, insula), emotion and memory (e.g., amygdala, hippocampus), sensory and motor processing (e.g., insula, precentral gyrus), and cognitive control and attention (e.g., prefrontal cortex, cingulate) in obese individuals. Although a great amount of research using these techniques has already unveiled the influence of different neural response patterns on obesogenic behaviors, in this chapter we will, otherwise, try to highlight the effects of obesity on specific neuronal circuits and discuss recent developments in fMRI-based neurofeedback approaches as an alternative in obesity treatment.

Serotonin Transporter Binding in the Diencephalon Is Reduced in Insulin-Resistant Obese Humans

BACKGROUND

Altered brain dopaminergic and serotonergic pathways have been shown in obese rodents and humans, but it is unknown whether this is related to obesity per se or to the metabolic derangements associated with obesity.

METHODS

We performed a case-control study in insulin-sensitive obese (ISO) and insulin-resistant obese (IRO) subjects (n = 12) and age-matched lean controls (n = 8) and measured serotonin transporter (SERT) binding in the whole diencephalon and specifically in the hypothalamus, as well as dopamine transporter (DAT) binding in the striatum using 123I- FP-CIT single-photon emission computed tomography. We assessed insulin sensitivity using the homeostatic model assessment of insulin resistance.

RESULTS

BMI did not differ between the IRO and ISO subjects. SERT binding in the diencephalon was significantly lower in IRO than in ISO subjects, but was not different between lean and obese subjects. SERT binding in the hypothalamus tended to be reduced in obese versus lean subjects, but was not different between IRO and ISO subjects. Striatal DAT binding was similar between lean and obese subjects as well as between ISO and IRO subjects.

CONCLUSIONS

We conclude that SERT binding in the diencephalon is reduced in insulin-resistant subjects independently of body weight, while hypothalamic SERT binding tends to be lower in obesity, with no difference between insulin-resistant and insulin-sensitive subjects. This suggests that the metabolic perturbations associated with obesity independently affect SERT binding within the diencephalon.

A systematic investigation of the differential roles for ventral tegmentum serotonin 1- and 2-type receptors on food intake in the rat

Central serotonin (5-HT) pathways are known to influence feeding and other ingestive behaviors. Although the ventral tegmentum is important for promoting the seeking and consumption of food and drugs of abuse, the roles of 5-HT receptor subtypes in this region on food intake have yet to be comprehensively examined. In these experiments, food restricted rats were given 2-h access to rat chow; separate groups of non-restricted animals had similar access to a sweetened fat diet. Feeding and locomotor activity were monitored following ventral tegmentum stimulation or blockade of 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B, or 5-HT2C receptors. 5-HT1A receptor stimulation transiently inhibited rearing behavior and chow intake in food-restricted rats, and had a biphasic effect on non-restricted rats offered the palatable diet. 5-HT1B receptor agonism transiently inhibited feeding in restricted animals, but did not affect intake of non-restricted rats. In contrast, 5-HT1B receptor antagonism decreased palatable feeding. Although stimulation of ventral tegmental 5-HT2B receptors with BW723C86 did not affect hunger-driven food intake, it significantly affected palatable feeding, with a trend for an increasing intake at 2.0µg/side but not at 5.0µg/side. Antagonism of the same receptor modestly but significantly inhibited feeding of the palatable diet at 5.0µg/side ketanserin. Neither stimulation nor blockade of 5-HT2A or 5-HT2C receptors caused prolonged effects on intake or locomotion. These data suggest that serotonin's effects on feeding within the ventral tegmentum depend upon the specific receptor targeted, as well as whether intake is motivated by food restriction or the palatable nature of the offered diet.

Anxiolytic profile of fluoxetine as monitored following repeated administration in animal rat model of chronic mild stress

Background: Fluoxetine, a selective serotonin re-uptake inhibitor (SSRI), has been proposed to be more effective as an antidepressive drug as compared to other SSRIs. After chronic SSRI administration, the increase in synaptic levels of 5-HT leads to desensitization of somatodentritic 5-HT autoreceptors in the raphe nuclei. Chronic stress may alter behavioral, neurochemical and physiological responses to drug challenges and novel stressors. Methods: Twenty four male rats were used in this study. Animals of CMS group were exposed to CMS. Animals of stressed and unstressed group were administrated with fluoxetine at dose of 1.0 mg/kg s well as 5.0 mg/kg repeatedly for 07 days 1 h before exposed to CMS. The objective of the present study was to evaluate that repeated treatment with fluoxetine could attenuate CMS-induced behavioral deficits. Results: Treatment with fluoxetine attenuated CMS-induced behavioral deficits. Fluoxetine administration induced hypophagia in unstressed as well as CMS rats. Acute and repeated administration of fluoxetine increased motor activity in familiar environment but only repeated administration increased exploratory activity in open field. Anxiolytic effects of fluoxetine were greater in unstressed rats. These anxiolytic effects were produced as result of repeated administration not on acute administration of fluoxetine at 1.0 mg/kg as well as 5.0 mg/kg. Conclusion: The present study demonstrated that CMS exposure resulted into behavioral deficits and produced depressive-like symptoms. Fluoxetine, an SSRI, administration attenuated behavioral deficits induced by CMS. Anxiolytic effects of repeated fluoxetine administration were greater in unstressed than CMS animals.

Gene polymorphisms as a predictor of body weight loss after Roux-en-Y gastric bypass surgery among obese women

This study aimed to investigate the association between twelve gene polymorphisms and body weight loss, 12 months after Roux-en-Y gastric bypass (RYGB) surgery. Three hundred and fifty-one obese women participated in this study. The statistical software WEKA was used to identify which gene polymorphisms were potential predictors of postoperative percentage of excess weight loss (%EWL). Our results indicate that the only gene polymorphism that predicted %EWL was rs3813929, which is related to the serotonin receptor gene (5-HT2C). Therefore, the 5-HT2C gene polymorphism rs3813929 (more specifically, the TT genotype) predicted greater %EWL 12 months after RYGB surgery among female patients.

Brain dopamine and serotonin transporter binding are associated with visual attention bias for food in lean men

BACKGROUND

In rodents, the striatal dopamine (DA) system and the (hypo)thalamic serotonin (5-HT) system are involved in the regulation of feeding behavior. In lean humans, little is known about the relationship between these brain neurotransmitter systems and feeding. We studied the relationship between striatal DA transporters (DAT) and diencephalic 5-HT transporters (SERT), behavioral tasks and questionnaires, and food intake.

METHOD

We measured striatal DAT and diencephalic SERT binding with [123I]FP-CIT SPECT in 36 lean male subjects. Visual attention bias for food (detection speed and distraction time) and degree of impulsivity were measured using response-latency-based computer tasks. Craving and emotional eating were assessed with questionnaires and ratings of hunger by means of VAS scores. Food intake was assessed through a self-reported online diet journal.

RESULTS

Striatal DAT and diencephalic SERT binding negatively correlated with food detection speed (p = 0.008, r = -0.50 and p = 0.002, r = -0.57, respectively), but not with food distraction time, ratings of hunger, craving or impulsivity. Striatal DAT and diencephalic SERT binding did not correlate with free choice food intake, whereas food detection speed positively correlated with total caloric intake (p = 0.001, r = 0.60), protein intake (p = 0.01, r = 0.44), carbohydrate intake (p = 0.03, r = 0.39) and fat intake (p = 0.06, r = 0.35).

CONCLUSIONS

These results indicate a role for the central 5-HT and DA system in the regulation of visual attention bias for food, which contributes to the motivation to eat, in non-obese, healthy humans. In addition, this study confirms that food detection speed, measured with the latency-based computer task, positively correlates with total food and macronutrient intake.

Serotonin and histamine mediate gastroprotective effect of fluoxetine against experimentally-induced ulcers in rats

Research in the treatment of gastric ulcer has involved the investigation of new alternatives, such as anti-depressant drugs. The present study was designed to investigate the gastroprotective effects of fluoxetine against indomethacin and alcohol induced gastric ulcers in rats and the potential mechanisms of that effect. Fluoxetine (20 mg/kg) was administered IP for 14 days. For comparative purposes, other rats were treated with ranitidine (30 mg/kg). Thereafter, after 24 h of fasting, INDO (100 mg/kg) or absolute alcohol (5 ml/kg) was administered to all rats (saline was administered to naïve controls) and rats in each group were sacrificed 5 h (for INDO rats) or 1 h (for alcohol rats) later. Macroscopic examination revealed that both fluoxetine and ranitidine decreased ulcer scores in variable ratios, which was supported by microscopic histopathological examination. Biochemical analysis of fluoxetine- or ranitidine-pre-treated host tissues demonstrated reductions in tumor necrosis factor (TNF)-α and myeloperoxidase (MPO) levels and concomitant increases in gastric pH, nitric oxide (NO) and reduced glutathione (GSH) contents. Fluoxetine, more than ranitidine, also resulted in serotonin and histamine levels nearest to control values. Moreover, immuno-histochemical analysis showed that fluoxetine markedly enhanced expression of cyclo-oxygenases COX-1 and COX-2 in both models; in comparison, ranitidine did not affect COX-1 expression in either ulcer model but caused moderate increases in COX-2 expression in INDO-induced hosts and high expression in alcohol-induced hosts. The results here indicated fluoxetine exhibited better gastroprotective effects than ranitidine and this could be due to anti-secretory, anti-oxidant, anti-inflammatory and anti-histaminic effects of the drug, as well as a stabilization of gastric serotonin levels.

A Concise Synthesis of Racemic Lorcaserin

We report herein the concise synthesis of racemic lorcaserin (±)-1, which is an anti-obesity drug. The synthetic route involved the key synthesis of an asymmetrical imide intermediate 11 and its efficient reduction. Imide 11 was synthesized directly by the reaction of nitrile 9 with acid 10. The reducing system of NaBH4, AlCl3, and trimethylsilyl chloride efficiently fulfilled the reduction of imide 11 to amine 8a, which could be converted to (±)-1 via Friedel–Crafts reaction as reported. This route afforded 69 % two-step yield of 8a from 9 via 11, and the concise synthesis of (±)-1 was completed in three steps. This route offers an alternative pathway to the synthesis of (±)-1 and its analogues.

Associations between central nervous system serotonin, fasting glucose, and hostility in African American females

BACKGROUND

Previous research has shown an association between hostility and fasting glucose in African American women. Central nervous system serotonin activity is implicated both in metabolic processes and in hostility related traits.

PURPOSE

The purpose of this study is to determine whether central nervous system serotonin influences the association between hostility and fasting glucose in African American women.

METHODS

The study consisted of 119 healthy volunteers (36 African American women, 27 White women, 21 White males, and 35 African American males, mean age 34 ± 8.5 years). Serotonin related compounds were measured in cerebrospinal fluid. Hostility was measured by the Cook-Medley Hostility Scale.

RESULTS

Hostility was associated with fasting glucose and central nervous system serotonin related compounds in African American women only. Controlling for the serotonin related compounds significantly reduced the association of hostility to glucose.

CONCLUSIONS

The positive correlation between hostility and fasting glucose in African American women can partly be explained by central nervous system serotonin function.

Pharmacotherapy of binge-eating disorder: a review

OBJECTIVES

The purpose of this article is to provide a comprehensive review of pharmacotherapy for binge eating disorder, including new therapeutic approaches such as centrally acting sympathomimetics, nootropics, lisdexamfetamine, and substance abuse treatment agents such as acamprosate, sodium oxybate, baclofen, and naltrexone.

METHODS

The study was conducted by searching the MEDLINE database using the keywords "binge eating disorder," "obesity," and "pharmacological therapy."All available studies on each drug dating from 1988 to the present were considered, focusing mainly on randomized controlled trials (RCTs). Other types of studies were considered when no RCTs were found. We drafted separate tables for open-label studies (), RCT (), and retrospective studies (). Each study is detailed by the number of subjects, additional design considerations, doses, results, additional main comparators, and study limitations.

RESULTS

The data emerging from this study seem to show that, at least in the short term, some specific medications within the classes of antidepressants, anticonvulsants, and antiobesity agents may prove promising in achieving the main objectives in the treatment of binge eating disorder: reducing the frequency of binge eating, reducing weight, and improving the associated psychopathology. The major limitation in interpreting these results is the short duration of the studies and the lack of adequately sized trials, or trials including patients with medical comorbidities.Good results are being obtained with new combinations of drugs and with substance abuse treatment agents. Although the precise nature of the relationship between substance use disorders and binge eating disorder remains to be clarified, the evidence suggests that treatments recognized as effective for substance use disorders may be useful as novel treatments for binge eating disorder. This field of research remains open to future studies with more precise methodological approaches and more detailed parameter assessment; a multidisciplinary approach is also essential to better understand such a complex disease.