Hypothalamic regulation of appetite

The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism

Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.

An anatomically distinct subpopulation of orexin neurons project from the lateral hypothalamus to the olfactory bulb

Olfactory cues play a key role in natural behaviors such as finding food, finding mates, and avoiding predators. In principle, the ability of the olfactory system to carry out these perceptual functions would be facilitated by signaling related to an organism's physiological state. One candidate pathway includes a direct projection from the hypothalamus to the main olfactory bulb, the first stage of olfactory sensory processing. The pathway from the hypothalamus to the main olfactory bulb is thought to include neurons that express the neuropeptide orexin, although the proportion that is orexinergic remains unknown. A current model proposes that the orexin population is heterogeneous, yet it remains unknown whether the proportion that innervates the main olfactory bulb reflects a distinct subpopulation of the orexin population. Herein, we carried out combined retrograde tract tracing with immunohistochemistry for orexin-A in the mouse to define the proportion of hypothalamic input to the main olfactory bulb that is orexinergic and to determine what fraction of the orexin-A population innervates the bulb. The numbers and spatial positions of all retrogradely labeled neurons and all the orexin-A-expressing neurons were quantified in sequential sections through the hypothalamus. Retrogradely labeled neurons were found in the ipsilateral hypothalamus, of which 22% expressed orexin-A. The retrogradely labeled neurons that did and did not express orexin-A could be anatomically distinguished based on their spatial position and cell body area. Remarkably, only 7% of all the orexin-A neurons were retrogradely labeled, suggesting that only a small fraction of the orexin-A population directly innervate the main olfactory bulb. These neurons spatially overlapped with the orexin-A neurons that did not innervate the bulb, although the two cell populations were differentiated based on cell body area. Overall, these results support a model in which olfactory sensory processing is influenced by orexinergic feedback at the first synapse in the olfactory processing pathway.

Neurohormonal Changes in the Gut–Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery

Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut–brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut–brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.

Effect of Cyclic Heat Stress on Feeding-Related Hypothalamic Neuropeptides of Three Broiler Populations and Their Ancestor Jungle Fowl

Heat stress (HS) has been increasingly jeopardizing the sustainability of the poultry production. Moreover, modern high-performing chickens are far less able to withstand HS than their predecessors due to higher growth rate and metabolic rates. Performance losses caused by HS are mainly ascribed to decreases in feed consumption. Since feed intake is tightly controlled by the hypothalamic centers of hunger and satiety, we sought to determine the effect of chronic cyclic HS on the expression of feeding-related hypothalamic neuropeptides (FRHN) in unselected chickens (i.e., the ancestor junglefowl-JF) and three broiler lines from diverse stages of genetic selection (i.e., the slow growing ACRB, the moderate growing 95RN, and the fast growing MRB). From 29 to 56 days, birds (n = 150 birds for each population) were subjected to either thermoneutral (TN, 25°C) or cyclic heat stress (HS, 36°C, 0900-1,800 h) conditions. Molecular data were analyzed by two-way ANOVA with interaction between the main factors, namely environmental temperature and line. The expression of major FHRN, like neuropeptide Y, agouti-related peptide, proopiomelanocortin, and cocaine and amphetamine regulated transcript remained unchanged. However, melanocortin receptor 1 exhibited a line-dependent decreasing trend from JF to MRB under both TN and HS (p = 0.09), adiponectin expression showed a distinct trend toward significance with 95RB exhibiting the highest mRNA level irrespective of the environmental temperature (p = 0.08), and JF had a greater mRNA abundance of visfatin than ACRB under TN (p < 0.05). The hypothalamic integration of circadian information, acclimation to long-lasting HS exposure, stable hypothalamic pathways unaffected by evolution and genetic selection, focus on mRNA abundances, and use of the entire hypothalamus masking gene expression in specific hypothalamic nuclei are all possible explanations for the lack of variations observed in this study. In conclusion, this is the first assessment of the impacts of heat stress on feeding-related hypothalamic neuropeptides of chicken, with a valuable and informative comparison between the ancestor junglefowl and three differently performing broiler lines.

Neuropeptide Y and Metabolism Syndrome: An Update on Perspectives of Clinical Therapeutic Intervention Strategies

Through the past decade of research, the pathogenic mechanisms underlying metabolic syndrome have been suggested to involve not only the peripheral tissues, but also central metabolic regulation imbalances. The hypothalamus, and the arcuate nucleus in particular, is the control center for metabolic homeostasis and energy balance. Neuropeptide Y neurons are particularly abundantly expressed in the arcuate of the hypothalamus, where the blood-brain barrier is weak, such as to critically integrate peripheral metabolic signals with the brain center. Herein, focusing on metabolic syndrome, this manuscript aims to provide an overview of the regulatory effects of Neuropeptide Y on metabolic syndrome and discuss clinical intervention strategy perspectives for neurometabolic disease.

Patient initiation and maintenance of GLP-1 RAs for treatment of obesity

Introduction: Healthcare providers (HCPs) see many patients with obesity-related complications and are therefore well placed to help treat obesity itself. However, limited collated information exists to help HCPs with the practical use of anti-obesity medications (AOMs). We focus on the initiation and maintenance of a glucagon-like peptide-1 receptor agonist (GLP-1 RA) for weight management, liraglutide 3.0 mg. Literature search was conducted between 25-28 November 2019 on PubMed and ClinicalTrials.gov.Areas covered: Clinical trial and real-world data describing weight-loss efficacy, cardiometabolic risk factors, incidence of adverse events (AEs), and persistence are presented to assist HCPs with patient discussions. Practical considerations to overcome barriers to optimal use are provided, equipping HCPs with the information required to aid with adherence to and persistence with AOMs. The use of other GLP-1- RA therapies in obesity is discussed in light of the recent US Food and Drug Administration approval of semaglutide 2.4 mg for weight management.Expert opinion: Liraglutide 3.0 mg provides benefits regarding weight loss and improvements in cardiometabolic risk factors. Promising areas of future research in the field of obesity include dual receptor agonists and the combination of glucagon-like peptide-1 receptor agonists with other molecules.

Whole-brain activation signatures of weight-lowering drugs

OBJECTIVE

The development of effective anti-obesity therapeutics relies heavily on the ability to target specific brain homeostatic and hedonic mechanisms controlling body weight. To obtain further insight into neurocircuits recruited by anti-obesity drug treatment, the present study aimed to determine whole-brain activation signatures of six different weight-lowering drug classes.

METHODS

Chow-fed C57BL/6J mice (n = 8 per group) received acute treatment with lorcaserin (7 mg/kg; i.p.), rimonabant (10 mg/kg; i.p.), bromocriptine (10 mg/kg; i.p.), sibutramine (10 mg/kg; p.o.), semaglutide (0.04 mg/kg; s.c.) or setmelanotide (4 mg/kg; s.c.). Brains were sampled two hours post-dosing and whole-brain neuronal activation patterns were analysed at single-cell resolution using c-Fos immunohistochemistry and automated quantitative three-dimensional (3D) imaging.

RESULTS

The whole-brain analysis comprised 308 atlas-defined mouse brain areas. To enable fast and efficient data mining, a web-based 3D imaging data viewer was developed. All weight-lowering drugs demonstrated brain-wide responses with notable similarities in c-Fos expression signatures. Overlapping c-Fos responses were detected in discrete homeostatic and non-homeostatic feeding centres located in the dorsal vagal complex and hypothalamus with concurrent activation of several limbic structures as well as the dopaminergic system.

CONCLUSIONS

Whole-brain c-Fos expression signatures of various weight-lowering drug classes point to a discrete set of brain regions and neurocircuits which could represent key neuroanatomical targets for future anti-obesity therapeutics.

Calcitonin Gene-Related Peptide-Induced Phosphorylation of STAT3 in Arcuate Neurons Is a Link in the Metabolic Benefits of Portal Glucose

INTRODUCTION

Intestinal gluconeogenesis (IGN) exerts metabolic benefits in energy homeostasis via the neural sensing of portal glucose.

OBJECTIVE

The aim of this work was to determine central mechanisms involved in the effects of IGN on the control of energy homeostasis.

METHODS

We investigated the effects of glucose infusion into the portal vein, at a rate that mimics IGN, in conscious wild-type, leptin-deficient Ob/Ob and calcitonin gene-related peptide (CGRP)-deficient mice.

RESULTS

We report that portal glucose infusion decreases food intake and plasma glucose and induces in the hypothalamic arcuate nucleus (ARC) the phosphorylation of STAT3, the classic intracellular messenger of leptin signaling. This notably takes place in POMC-expressing neurons. STAT3 phosphorylation does not require leptin, since portal glucose effects are observed in leptin-deficient Ob/Ob mice. We hypothesized that the portal glucose effects could require CGRP, a neuromediator previously suggested to suppress hunger. In line with this hypothesis, neither the metabolic benefits nor the phosphorylation of STAT3 in the ARC take place upon portal glucose infusion in CGRP-deficient mice. Moreover, intracerebroventricular injection of CGRP activates hypothalamic phosphorylation of STAT3 in mice, and CGRP does the same in hypothalamic cells. Finally, no metabolic benefit of dietary fibers (known to depend on the induction of IGN), takes place in CGRP-deficient mice.

CONCLUSIONS

CGRP-induced phosphorylation of STAT3 in the ARC is part of the neural chain determining the hunger-modulating and glucose-lowering effects of IGN/portal glucose.

Thyroxine Treatment During the Perinatal Stage Prevents the Alterations in the ObRb-STAT3 Leptin Signaling Pathway Caused by Congenital Hypothyroidism

Thyroid hormone deficiency during crucial stages of development causes congenital hypothyroidism. This syndrome alters hypothalamic pathways involved in long-term bodyweight regulation as ObRb-STAT3 leptin signaling pathway, which is associated with metabolic syndrome. This study aimed to determine if thyroxine treatment during pregnancy and lactation in hypothyroid mothers avoids, in the congenital hypothyroid offspring, the alterations in metabolic programming related to metabolic syndrome and the ObRb-STAT3 leptin signaling pathway in hypothalamus. Twenty-four virgin female Wistar rats were divided into euthyroid, hypothyroid, and hypothyroid with thyroxine treatment (20 μg/kg/day T₄ since pregnancy until lactation). The bodyweight and energy intake, insulin resistance, glucose tolerance, metabolic and hormonal parameters were determined in offspring at 28 weeks after birth. Then, the rats were euthanized to obtain adipose tissue reserves and hypothalamus to measure the expression of ObRb, STAT3, pSTAT3, and SOCS3. Congenital hypothyroidism presented metabolic syndrome such as insulin resistance, glucose tolerance, dyslipidemias, an increase in cardiovascular risk (Castelli I males:166.67%, females: 173.56%; Castelli II males: 375.51%, females: 546.67%), and hypothalamic leptin resistance (SOCS3, Males: 10.96%, females: 25.85%). Meanwhile, the thyroxine treatment in the mothers during pregnancy and lactation prevents the metabolic disturbance. In conclusion, thyroxine treatment during the critical perinatal stage for metabolic programming prevents congenital hypothyroidism-caused metabolic syndrome and hypothalamic leptin resistance.

Neurochemical regulators of food behavior for pharmacological treatment of obesity: current status and future prospects

In recent decades, obesity has become a pandemic disease and appears to be an ultimate medical and social problem. Existing antiobesity drugs show low efficiency and a wide variety of side effects. In this review, we discuss possible mechanisms underlying brain-gut-adipose tissue axis, as well as molecular biochemical characteristics of various neurochemical regulators of body weight and appetite. Multiple brain regions are responsible for eating behavior, hedonic eating and food addiction. The existing pharmacological targets for treatment of obesity were reviewed as well.

Zingiber officinale (Roscoe) mitigates CCl4-induced liver histopathology and biochemical derangements through antioxidant, membrane-stabilizing and tissue-regenerating potentials

The world-wide increasing incidence of liver injury has attracted scientific interest in the exploration of better treatment or adjuvant treatment therapies. This study investigated the effects of methanol extract of Zingiber officinale (Roscoe) rhizome (MEZOR) in a Wistar rat model of carbon tetrachloride (CCl4)-induced liver injury. The study recruited thirty female Wistar rats that received graded doses of MEZOR (determined by its LD50) by oral gavage through an oral canula, for 4 consecutive weeks following 1 week oral administration of CCl4 (0.7 ml/kg in olive oil; 1:1, v/v) while livolin forte® (5.2 mg/kg p.o.) was used as a standard. CCl4 induced deleterious hepatic effects as revealed by the liver function biomarkers (AST, ALT, ALP and total protein), antioxidant indicators (GSH and CAT) and histopathological effects, demonstrated by H & E, Gordon and Sweet, Masson's trichrome, PAS staining techniques as well as by quantificational analyses of the liver micrographs, using image-J. MEZOR treatment was associated with a dose-dependent and significant mitigation of the aforementioned parameters (p < 0.05). This study concluded that MEZOR is a potential therapeutic choice in the adjuvant treatment of subjects with chemically-induced liver injury.

Sub-acute administration of lower doses of nicotine caused sex-dependent improvement of renal function in Wistar rats

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Exposure to nicotine is associated with sex-dependent variation in electrolyte disturbances.

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Lower doses of sub-acute nicotine administration enhanced renal function.

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Nicotine-enhanced renal function is more pronounced in female than in male Wistar rats.

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Nicotine-enhanced renal function may be mediated through α7-nAchR.

The adverse and beneficial health effects of nicotine (NIC), the major alkaloid found in cigarettes and tobacco, are controversial. Most studies on NIC have focused on its effects on cardiovascular and nervous functions. This study aimed at determining dose- and sex-specific effects of sub-acute (28 days) NIC administration on some indices of kidney function in Wistar rats. Forty rats (20 males and 20 females), 8–9 weeks old (each housed in separate metabolic cage), were used for this study such that graded doses of NIC (1, 2 and 4 mg/kg i.p. for 28 days) were administered to both sexes while each control received distilled water at 0.2 mL/100 g i.p. Blood was collected under ketamine anesthesia (10 mg/kg i.m) for analyses and results obtained were compared at p < 0.05. The result showed beneficial alterations in plasma and urine level of creatinine, urea and uric acid (p < 0.05) as well as plasma and urine electrolyte level (Na⁺ and K⁺) in both sexes (p < 0.05). Also, there was significant improvement in creatinine clearance (p < 0.05) with no appreciable difference in their histological examination. Although these beneficial effects were more pronounced in the female than in the male (p < 0.05), administration at the highest dose showed potentially deleterious alterations from normal beneficial trend (p < 0.05) in both sexes. It was concluded that sub-acute administration of lower doses of NIC improves kidney function of Wistar rats; an effect that was more pronounced in the females than their male counterparts.

Acetonic extract of Vernonia amygdalina (Del.) attenuates Cd-induced liver injury: Potential application in adjuvant heavy metal therapy

Exposure to cadmium (Cd), even at low doses, is of serious health concern because it does not undergo metabolic degradation to less toxic metabolite. Liver injury/disease, with a world-wide increasing incidence, is one of the consequences of exposure to Cd toxicity. This study aimed at determining the effects of acetonic extract of Vernonia amygdalina leaf (AEVAL) in a Wistar rat model of Cd-induced liver injury. Phytochemical screening of the extract was carried out and its oral LD₅₀ was determined to guide the choice of therapeutic doses. Thereafter, thirty male Wistar rats were recruited for this study. The experimental groups received 4 weeks oral graded doses of the extract (100, 200 and 400 mg/kg) following Cd-induced liver injury. Cd-induced liver injury (5 mg/kg i.p for 5 consecutive days) was characterized by deleterious alterations in the levels of AST, ALT, ALP, total bilirubin and hepatic total protein (p ˂ 0.05). Also, deleterious alteration of oxidative stress indicators (GSH, SOD and CAT) and lipid peroxidation index (TBARS) was observed in the liver homogenates. Histopathological examination showed evidence of degenerated hepatocytes as well as inflammation with disseminated steatosis. These conditions were significantly attenuated (p ˂ 0.05) following treatment with graded doses of the extract, with the highest dose expressing least therapeutic effects. This study concluded that AEVAL attenuated Cd-induced liver injury and is, potentially, a suitable option in adjuvant therapy for heavy metal toxicity.

Hypothalamic loss of Snord116 recapitulates the hyperphagia of Prader-Willi syndrome

Profound hyperphagia is a major disabling feature of Prader-Willi syndrome (PWS). Characterization of the mechanisms that underlie PWS-associated hyperphagia has been slowed by the paucity of animal models with increased food intake or obesity. Mice with a microdeletion encompassing the Snord116 cluster of noncoding RNAs encoded within the Prader-Willi minimal deletion critical region have previously been reported to show growth retardation and hyperphagia. Here, consistent with previous reports, we observed growth retardation in Snord116+/-P mice with a congenital paternal Snord116 deletion. However, these mice neither displayed increased food intake nor had reduced hypothalamic expression of the proprotein convertase 1 gene PCSK1 or its upstream regulator NHLH2, which have recently been suggested to be key mediators of PWS pathogenesis. Specifically, we disrupted Snord116 expression in the mediobasal hypothalamus in Snord116fl mice via bilateral stereotaxic injections of a Cre-expressing adeno-associated virus (AAV). While the Cre-injected mice had no change in measured energy expenditure, they became hyperphagic between 9 and 10 weeks after injection, with a subset of animals developing marked obesity. In conclusion, we show that selective disruption of Snord116 expression in the mediobasal hypothalamus models the hyperphagia of PWS.

Determinants of glucose metabolism and the role of NPY in the progression of insulin resistance in chronic migraine

Background Chronic migraine has a well-documented association with increased insulin resistance and metabolic syndrome. The hypothalamus may play a role in the progression of insulin resistance in chronic migraine through the regulation of orexigenic peptides such as neuropeptide Y. Insulin resistance may lead to increased risk of future type 2 diabetes mellitus in patients with chronic migraine, which is more likely to occur if other pathogenetic defects of type 2 diabetes mellitus, such as impaired pancreatic β-cell functions and defects in intestinal glucagon-like peptide-1 secretion after meals. We studied the relationship of fasting neuropeptide Y with insulin resistance, β-cell function, and glucagon-like peptide-1 secretion in non-obese female chronic migraine patients. We also aimed to investigate glucose-stimulated insulin and glucagon-like peptide-1 secretions as early pathogenetic mechanisms responsible for the development of carbohydrate intolerance. Methods In this cross-sectional controlled study, 83 non-obese female migraine patients of reproductive age categorized as having episodic migraine or chronic migraine were included. The control group consisted of 36 healthy females. We studied glucose-stimulated insulin and glucagon-like peptide-1 secretion during a 75 g oral glucose tolerance test. We investigated the relationship of neuropeptide Y levels with insulin resistance and β-cell insulin secretion functions. Results Fasting glucose levels were significantly higher in migraine patients. Plasma glucose and insulin levels during the oral glucose tolerance test were otherwise similar in chronic migraine, episodic migraine and controls. Patients with chronic migraine were more insulin resistant than episodic migraine or controls ( p = 0.048). Glucagon-like peptide-1 levels both at fasting and two hours after glucose intake were similar in chronic migraine, episodic migraine, and controls. Neuropeptide Y levels were higher in migraineurs. In chronic migraine, neuropeptide Y was positively correlated with fasting glucagon-like peptide-1 levels (r = 0.57, p = 0.04), but there was no correlation with insulin resistance (r = 0.49, p = 0.09) or β-cell function (r = 0.50, p = 0.07). Discussion Non-obese premenopausal female patients with chronic migraine have higher insulin resistance, but normal β-cell function is to compensate for the increased insulin demand during fasting and after glucose intake. Increased fasting neuropeptide Y levels in migraine may be a factor leading to increased insulin resistance by specific alterations in energy intake and activation of the sympathoadrenal system.

Gastro-protective effect of methanol extract of Vernonia amygdalina (del.) leaf on aspirin-induced gastric ulcer in Wistar rats

This study investigated the protective effects of methanol extract of Vernonia amygdalina leaf (MEVA) on aspirin induced gastric ulcer in rats. Thirty Wistar rats, 150-200 g were divided into six groups as follows: Group 1 (control) rats received 2 mL/kg of propylene glycol for 28 consecutive days. Group 2 (Ulcer Control) received 150 mg/kg/day of aspirin suspended in 3 mL of 1% carboxymethylcellulose in water orally for 3 consecutive days during which the rats were fasted for the induction of ulcer. Group 3 received cimetidine at 100 mg/kg/day orally for 28 consecutive days and thereafter treated as group 2. Groups 4, 5 and 6 received MEVA orally at 200, 300 and 400 mg/kg/day respectively for 28 consecutive days and thereafter were treated with aspirin as group 2. All the animals were sacrifice at the end of the study to determine the gastric pH, gastric acidity, gastric ulcer score, haematological indices, superoxide dismutase (SOD) activity, reduced glutathione (GSH) and Lipid peroxidation (LPO) levels. The result showed that aspirin significantly (p < 0.05) increased gastric ulcer score and index, decreased gastric pH, gastric acidity, SOD activity, GSH level as well as increased LPO level. It induced significant necrosis of the stomach tissue. Administration of MEVA significantly (p < 0.05) increased gastric pH, but decreased gastric acid secretion and reversed alteration of haematological parameters. It also significantly (p < 0.05) increased SOD activity, GSH level and decreased LPO level. The results suggest that Vernonia amygdalina possesses gastro-protective properties against aspirin-induced gastric ulcer.

Harnessing glucagon-like peptide-1 receptor agonists for the pharmacological treatment of overweight and obesity

Over the past 30 years, there has been a dramatic rise in global obesity prevalence, resulting in significant economic and social consequences. Attempts to develop pharmacological agents to treat obesity have met with many obstacles including the lack of long-term effectiveness and the potential for adverse effects. Historically, there have been limited treatment options for overweight and obesity; however, since 2012, a number of new drugs have become available. A number of peptides produced in the gut act as key mediators of the gut-brain axis, which is involved in appetite regulation. This review discusses the role of the gut-brain axis in appetite regulation with special focus on glucagon-like peptide-1. Liraglutide 3.0 mg, a glucagon-like peptide-1 receptor agonist that targets this pathway, is now approved for the treatment of obesity and overweight (body mass index ≥27 kg/m² ) with comorbidities such as type 2 diabetes, high blood pressure, high cholesterol or obstructive sleep apnoea. In addition, other glucagon-like peptide-1 receptor agonists offer promise for obesity management in the future. This review examines how glucagon-like peptide-1 receptor agonists promote weight loss and summarizes the clinical data on weight loss with glucagon-like peptide-1 receptor agonists.

Emerging drugs for the treatment of obesity

INTRODUCTION

The increasing prevalence of obesity represents a huge threat to public health and the current pharmacological treatment options are limited. Bariatric surgery is by far the most effective treatment for severe obesity, highlighting the urgent need for new and improved drug therapies. Areas covered: Based on the physiological regulation of energy homeostasis, pharmacological strategies to treat obesity are evaluated with focus on drugs in phase 2 and 3 clinical development. The potential impact of these drugs on current treatment standards and the barriers for development are discussed and set in a historical perspective of previous antiobesity medications. Expert opinion: The radical effects of bariatric surgery have extended our understanding of the mechanisms controlling appetite and boosted the search for new drug targets in obesity treatment. Accordingly, several compounds targeting the central nervous system and/or periphery are in pipeline for obesity. These drugs should be evaluated over a wide array of end-points; in particular, long-term safety monitoring is necessary as serious adverse events may appear. Combination therapy targeting more than one pathway controlling energy balance might be necessary to achieve substantial weight loss while minimising side effects.

Neuro-endocrine effects of aqueous extract of Amaranthus viridis (Linn.) leaf in male Wistar rat model of cyclophosphamide-induced reproductive toxicity

Cyclophosphamide (CP) is a widely used cytotoxic alkylating agent with antitumor and immunosuppressant properties that is associated with various forms of reproductive toxicity. The significance of natural antioxidants of plant origin should be explored, especially in a world with increasing incidence of patients in need of chemotherapy. The neuro-endocrine effects of aqueous extract of Amaranthus viridis (Linn.) leaf (AEAVL) in Wistar rats with CP-induced reproductive toxicity was determined. Forty rats were used for this study such that graded doses of the extract were administered following CP-induced reproductive toxicity and comparisons were made against control, toxic and standard (vitamin E) groups at p < 0.05. The synthetic drugs (CP, 65 mg/kg i.p. for 5 days; Vitamin E, 100 mg/kg p.o. for 30 days) as well as the extract (100, 200 and 400 mg/kg p.o. for 30 days) were administered to the rats at 0.2 mL/100 g. CP induced reproductive toxicity as evidenced by significantly lowered levels of FSH, LH and testosterone, perturbation of sperm characterization, deleterious disruptions of the antioxidant system as evidenced by decreased levels of GSH as well as elevation of TBARS activity. Histopathological examination showed hemorrhagic lesions with scanty and hypertrophied parenchymal cells in the pituitary while the testis showed ballooned seminiferous tubules with loosed connective tissues and vacuolation of testicular interstitium. These conditions were significantly reversed (p < 0.05) following administration of the graded doses of the extract. It was, therefore, concluded that AEAVL could potentially be a therapeutic choice in patients with CP-induced neuro-endocrine dysfunction and reproductive toxicity.

Amelioration of Cadmium-Induced Nephropathy using Polyphenol-rich Extract of Vernonia amygdalina (Del.) Leaves in Rat Model

AIM

To determine the effects of polyphenol-rich extract of the leaves of Vernonia amygdalina (PEVA) in rats with Cd-induced nephropathy.

MATERIALS AND METHODS

Sixty five male Wistar rats were divided into five groups as follows; Group 1 received distilled water throughout the period of study. Group 2 received 5 mg/kg body weight of cadmium (Cd), in the form of CdSO4, for five consecutive days via intraperitoneal route. Groups 3, 4 and 5 were pretreated with Cd as group 2 and thereafter received oral treatment of PEVA for 4 weeks at 100 mg/kg, 200 mg/kg and 400 mg/kg body weight, respectively.

RESULTS

Exposure to Cd toxicity significantly induced deleterious alterations in plasma and urine levels of creatinine, urea and glucose as well as creatinine and urea clearance (p < 0.05) in the rat model. There was a significant disturbance in the antioxidant system as revealed by the levels of thiobarbituric acid reactive substance (TBARS) and reduced glutathione (GSH) (p < 0.05) in the kidney tissue of the rats. With marked improvements in renal histoarchitecture, PEVA treatment showed a duration and non dose-dependent ameliorative potential.

CONCLUSION

PEVA treatment reversed the compromise of renal function that was induced by Cd toxicity in rat model.

Polyphenol-rich extract of Vernonia amygdalina (Del.) leaves ameliorated cadmium-induced alterations in feeding pattern and urine volume of male Wistar rats

Aim:

To determine the effects of a polyphenol-rich extract of the leaves of Vernonia amygdalina (PEVA) on the feeding pattern of rats that are exposed to cadmium (Cd) toxicity.

Materials and Methods:

Thirty male Wistar rats, weighing 160-180 g, were divided into 6 groups of 5 rats each as follows; Group 1 received distilled water orally (0.2 ml a 100 g rats), daily, throughout the period of study. Group 2 received Cd alone (in the form of CdSO₄) at 5 mg/kg/day via intraperitoneal route for 5 consecutive days. Group 3 were pre-treated with Cd as Group 2 and thereafter left untreated for a period of 4-week. After the oral lethal dose of PEVA was determined, Groups 4, 5, and 6 received graded doses of PEVA at 100, 200 and 400 mg/kg/day (0.2 ml per 100 g rats), respectively via oral route for 4 weeks after they were pre-treated with Cd as Group 2. Blood samples were collected for some plasma biochemical assays while urine samples were collected using metabolic cages.

Results:

PEVA administration significantly increased (P < 0.05) the body weight and feeding patterns that were significantly reduced (P < 0.05) by Cd toxicity. PEVA also significantly reinstated the plasma antioxidant status, as well as glucose and urine volume of the rats toward control values (P < 0.05).

Conclusion:

PEVA can be an herbal alternative in the treatment or management of subjects manifesting alterations in feeding pattern and urine volume that is Cd-induced.

Ghrelin signalling and obesity: at the interface of stress, mood and food reward

The neuronal circuitry underlying the complex relationship between stress, mood and food intake are slowly being unravelled and several studies suggest a key role herein for the peripherally derived hormone, ghrelin. Evidence is accumulating linking obesity as an environmental risk factor to psychiatric disorders such as stress, anxiety and depression. Ghrelin is the only known orexigenic hormone from the periphery to stimulate food intake. Plasma ghrelin levels are enhanced under conditions of physiological stress and ghrelin has recently been suggested to play an important role in stress-induced food reward behaviour. In addition, chronic stress or atypical depression has often demonstrated to correlate with an increase in ingestion of caloric dense 'comfort foods' and have been implicated as one of the major contributor to the increased prevalence of obesity. Recent evidence suggests ghrelin as a critical factor at the interface of homeostatic control of appetite and reward circuitries, modulating the hedonic aspects of food intake. Therefore, the reward-related feeding of ghrelin may reveal itself as an important factor in the development of addiction to certain foods, similar to its involvement in the dependence to drugs of abuse, including alcohol. This review will highlight the accumulating evidence demonstrating the close interaction between food, mood and stress and the development of obesity. We consider the ghrelinergic system as an effective target for the development of successful anti-obesity pharmacotherapies, which not only affects appetite but also selectively modulates the rewarding properties of food and impact on psychological well-being in conditions of stress, anxiety and depression.