Neotomodon alstoni mice present sex differences between lean and obese in daily hypothalamic leptin signaling

This article compared the effects of spontaneous obesity on the daily profile in the relative amount of the leptin receptor (LepRb), and its output. That is the precursor Pro-opiomelanocortin (POMC) over a 24-hour period and compared with differences in locomotion and food intake in periods of artificial light. Differences between lean and obese mice were examined, as were sex differences. Body weight, food intake and locomotor activity were monitored in freely moving lean and obese mice. Hypothalamic tissue was collected at 5 h, 10 h, 15 h, 19 h and 24 h. Samples were analyzed by western blotting to determine the relative presence of protein for LepRb, STAT3 phosphorylation (by pSTAT3/STAT3 ratio) and POMC. Obese mice were 60% less active in locomotion than lean mice during the night. While both locomotor activity and food intake were noticeably greater during the day in obese mice than in lean mice, the hypothalamus in obese mice showed a lower relative abundance of POMC and reduced pSTAT3/STAT3 ratio and leptin receptors. Behavioral and biochemical differences were more evident in obese females than in obese males. These results indicate that obesity in N. alstoni affects hypothalamic leptin signaling according to sex.     

Day-night variations in pro-oxidant reactions of hypothalamic,hepatic and pancreatic tissue in mice with spontaneous obesity (Neotomodon alstoni)

Objectives: The present work compares the pro-oxidant properties in hypothalamic, hepatic, and pancreatic tissue of spontaneously obese and lean Neotomodon alstoni during day and night. Methods: Lipid peroxidation from hypothalamus, liver, and pancreas from lean and obese mice were quantified by the two-thiobarbituric acid method. Lipid peroxidation in vivo was also determined by means of detection of conjugated dienes in lipid extracts. Results: Hypothalamic tissue from obese Neotomodon showed a notorious increase (nearly 700%) in the production of thiobarbituric acid-reactive substances (TBARS) at day, either in basal as well as in an assay supplemented with Fe²⁺; the presence of conjugated dienes was also notably greater (76%) at day. Hypothalamus of lean mice presented an increase (170%) in assay supplemented with Fe²⁺. Hepatic tissue in obese mice showed diurnal increasing in TBARS + Fe²⁺ (34%) and in conjugated dienes (38%), while lean mice showed only a diurnal increase (45%) in TBARS + Fe²⁺. Pancreatic tissue from obese mice presented a diurnal increasing in basal TBARS (130%) but a decrease (72%) in TBARS + Fe²⁺. Presence of conjugated dienes was also decreased during the day in lean (60%) and in obese (40%) mice. Conclusions: In the obese Neotomodon, there is a larger day–night change in pro-oxidant status in the hypothalamus and in pancreas than the one observed in the liver, suggesting a differential equilibrium between oxidative reactions and antioxidant defenses in the different tissues during the day–night cycle.     

Effects of obesity on circadian photic entrainment of locomotor activity in wild mice Neotomodon alstoni

Obesity is increasing in industrialized countries at an alarming rate. Recent studies have linked this condition with changes in the circadian regulation, and circadian clock dysfunctions have also been linked to metabolic disorders. When in captivity and fed a regular rodent chow diet ad libitum some volcano mice, Neotomodon alstoni (endemic species of Mexico) become overweight and display symptoms equivalent to metabolic syndrome. The aim of this work was to observe whether there are significant changes in the functional properties of the circadian system, namely in the entraining circadian locomotor activity rhythm, between mice that became obese and normal adult mice. Freely moving circadian rhythms of locomotor activity were tested under constant conditions as well as under conditions of discrete and continuous entrainment. Our results show that volcano lean mice present a phase response curve with larger delays than advances, indicating that re-entrainment is more easily achieved by delays. Volcano obese mice are less efficient at re-entraining because they show smaller phase shifts in delays than control mice. These results indicate that obesity in N. alstoni has a negative effect on the circadian mechanisms that integrate the photic entrainment.     

Endurance training prevents inflammation and apoptosis in hypothalamic neurons of obese mice

This study investigated the effects of exercise training in regulating inflammatory processes, endoplasmic reticulum stress, and apoptosis in hypothalamic neurons of obese mice. Swiss mice were distributed into three groups: Lean mice (Lean), sedentary animals fed a standard diet; obese mice (Obese), sedentary animals fed a high-fat diet (HFD); trained obese mice (T. Obese), animals fed with HFD and concurrently subjected to an endurance training protocol for 8 weeks. In the endurance training protocol, mice ran on a treadmill at 60% of peak workload for 1 hr, 5 days/week for 8 weeks. Twenty-four hours after the last exercise session, the euthanasia was performed. Western blot, quantitative real-time polymerase chain reaction, and terminal deoxynucleotide transferase biotin-dUTP nick end-labeling (TUNEL) techniques were used for the analysis of interest. The results show exercise training increased phosphorylation of leptin signaling pathway proteins (pJAK2/pSTAT3) and reduced the content of tumor necrosis factor α, toll-like receptor 4, suppressor of cytokine signaling 3, protein–tyrosine phosphatase 1B as well as the phosphorylation of IkB kinase in the hypothalamus of T. Obese animals. A reduction of macrophage activation and phosphorylation of eukaryotic initiation factor 2α, and protein kinase RNA-like endoplasmic reticulum kinase (PERK) were also observed in exercised animals. Furthermore, exercise decreased the expression of the proapoptotic protein (PARP1) and increased anti-inflammatory (IL-10) and antiapoptotic (Bcl2) proteins. Using the TUNEL technique, we observed that the exercised animals had lower DNA fragmentation. Finally, physical exercise preserved pro-opiomelanocortin messenger RNA content. In conclusion, exercise training was able to reorganize the control of the energy balance through anti-inflammatory and antiapoptotic responses in hypothalamic tissue of obese mice.     

A truncating mutation of Alms1 reduces the number of hypothalamic neuronal cilia in obese mice

Primary cilia are ubiquitous cellular antennae whose dysfunction collectively causes various disorders, including vision and hearing impairment, as well as renal, skeletal, and central nervous system anomalies. One ciliopathy, Alström syndrome, is closely related to Bardet–Biedl syndrome (BBS), sharing amongst other phenotypic features morbid obesity. As the cellular and molecular links between weight regulation and cilia are poorly understood, we used the obese mouse strain foz/foz, bearing a truncating mutation in the Alström syndrome protein (Alms1), to help elucidate why it develops hyperphagia, leading to early onset obesity and metabolic anomalies. Our in vivo studies reveal that Alms1 localizes at the base of cilia in hypothalamic neurons, which are implicated in the control of satiety. Alms1 is lost from this location in foz/foz mice, coinciding with a strong postnatal reduction (～70%) in neurons displaying cilia marked with adenylyl cyclase 3 (AC3), a signaling protein implicated in obesity. Notably, the reduction in AC3‐bearing cilia parallels the decrease in cilia containing two appetite‐regulating proteins, Mchr1 and Sstr3, as well as another established Arl13b ciliary marker, consistent with progressive loss of cilia during development. Together, our results suggest that Alms1 maintains the function of neuronal cilia implicated in weight regulation by influencing the maintenance and/or stability of the organelle. Given that Mchr1 and Sstr3 localization to remaining cilia is maintained in foz/foz animals but known to be lost from BBS knockout mice, our findings suggest different molecular etiologies for the satiety defects associated with the Alström syndrome and BBS ciliopathies. © 2012 Wiley Periodicals, Inc. Develop Neurobiol, 2013     

Assessment of copper and lipid profile in obese children and adolescents

The aim of this study was to assess erythrocyte and plasma copper concentrations and correlate them with the lipid profile of overweight and obese children and adolescents. The study was performed with 15 over-weight and 30 obese children and adolescents, and the results were compared to the control group (21), aged 6–16 yr. Anthropometric assessment was carried out using body mass index (BMI). Total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride serum levels were investigated. Erythrocyte and plasma copper levels were determined by atomic absorption spectrophotometry. Greater alterations in the lipid profile were observed in HDL-cholesterol, LDL-cholesterol, and triglyceride levels, with distinctions according to gender. The plasma copper concentrations in the overweight and obese male groups were significantly higher than those in the control group (p=0.0006). Negative correlations between plasma copper and total cholesterol (r=−0.54) and LDL cholesterol (r=−0.59) were observed in the obese male group. There was no statistical difference in copper erythrocyte concentrations. The obesity associated to disorders in lipid metabolism predisposes to changes in copper plasma concentrations, but there was no alteration in intracellular reserves, which suggests an important homeostatic control to compensate for plasma oscillations and metabolic alterations of the disease.     

Effect of gastric bypass on spontaneous growth hormone and ghrelin release profiles

Objective : The purpose of this study was to analyze growth hormone (GH) concentrations in obese women before and after Roux‐en‐Y gastric bypass (RYGBP) and how resulting changes in weight, fat mass, ghrelin levels, and insulin sensitivity affect GH secretion. Research Methods and Procedures : Blood was sampled at 20‐minute intervals for 24 hours in 10 non‐diabetic premenopausal severely obese women before and 6 months after RYGBP. GH concentrations were measured in all samples, and serum ghrelin was collected at five time‐points. Results : After a 27% BMI drop (55.9 ± 6.2 to 40.7 ± 5.8 kg/m²), blunted GH profiles underwent partial recovery. Basal, postprandial, and mean ghrelin concentrations were not changed. A negative correlation was found between mean GH levels and insulin and homeostasis model assessment (p < 0.01). BMI accounted for 54% of GH variation. Discussion : Partial recovery of GH secretion after RYGBP‐induced weight loss suggests that a blunted secretion is not a causal factor of obesity but a consequence of the obese state and does not seem to be ghrelin‐level dependent.     

Association of apolipoprotein B XbaI gene polymorphism and lipid profile in northern Indian obese

BACKGROUND:

Over the last few decades, obesity, diabetes, and hypertension have become main health evils. The health problems of obesity are well-recognized. However, the fact that all obese individuals are not at the same risk of developing a disease is also recognized. The apolipoprotein B (APOB) plays a central role in lipid metabolism. So we compare the association of APOB XbaI gene polymorphism and lipid profile total in obese north Indian population.

MATERIALS AND METHODS:

A total of 132 obese (body mass index [BMI] >25 kg/m²) and 132 age matched non-obese (BMI ≤ 25 kg/m²) subjects were studied after taking detailed clinical profile. Lipid profile in serum/plasma was done using commercial kits. Genetic analysis of APOB XbaI was done using Polymerase Chain Reaction-Restriction Fragment Leanth polymorphism (PCR-RFLP).

STATISTICAL ANALYSIS:

Statistical analysis was performed by Statistical Package for the Social Sciences (SPSS) (version 11.5) software (IBM Corporation). All continuous variables were expressed as mean ± SD and tested by analysis of variance test. Comparisons of categorical variables were assessed using χ² tests or Fisher''s exact test. P < 0.05 was considered as significant.

RESULTS:

Analysis showed that obese subjects had significantly higher value of the waist-to-hip ratio, blood pressure (systolic and diastolic), and lipid profile. In APOB XbaI gene polymorphism, we did not find significant differences in genotype or allele frequencies. Moreover, none of the studied metabolic parameters (lipid profile) showed any association with the gene polymorphism.

CONCLUSIONS:

Study reveals no considerable association of APOB XbaI gene polymorphism with obesity and lipid profile in north Indians.     

Decreased rate of fatty acid synthesis in brown adipose tissue of hypothalamic obese rats

Intranuclear coinjection of the late SV40 KpnI/BclI DNA fragment and the early promotor/enhancer HpaII/BglI DNA segment into permissive monkey and non-permissive mouse cells allows late SV40 gene expression without T-antigen synthesis and DNA replication. These conditions were chosen to analyse the effect of DNA methylation on V-antigen synthesis detached from the process of DNA replication. We found that in vitro methylation of a single cytosine nucleotide proximal to the major late mRNA cap site by the HpaII methylase does not block capsid protein synthesis. This result is in contrast to reported data obtained in Xenopus laevis oocyte injection experiments [(1982) Proc. Natl. Acad. Sci. USA 79, 5142-5146].     

Acute physical exercise increases leptin-induced hypothalamic extracellular signal-regulated kinase1/2 phosphorylation and thermogenesis of obese mice

The obesity is a result of energy imbalance and the increase in thermogenesis seems an interesting alternative for the treatment of this disease. The mechanism of energy expenditure through thermogenesis is tightly articulated in the hypothalamus by leptin. The hypothalamic extracellular signal-regulated kinase-1/2 (ERK1/2) is a key mediator of the thermoregulatory effect of leptin and mediates the sympathetic signal to the brown adipose tissue (BAT). In this context, physical exercise is one of the main interventions for the treatment of obesity. Thus, this study aimed to verify the effects of acute physical exercise on leptin-induced hypothalamic ERK1/2 phosphorylation and thermogenesis in obese mice. Here we showed that acute physical exercise reduced the fasting glucose of obese mice and increased leptin-induced hypothalamic p-ERK1/2 and uncoupling protein 1 (UCP1) content in BAT ( P < 0.05). These molecular changes are accompanied by an increased oxygen uptake (VO ₂) and heat production in obese exercised mice ( P < 0.05). The increased energy expenditure in the obese exercised animals occurred independently of changes in spontaneous activity. Thus, this is the first study demonstrating that acute physical exercise can increase leptin-induced hypothalamic ERK1/2 phosphorylation and energy expenditure of obese mice.     

Behavioural and autonomic thermoregulation in lean and genetically obese (ob/ob) mice

1. 1.|The capacity for behavioural thermoregulation has been assessed in lean and genetically obese (ob/ob) mice, using operant conditioning.

2. 2.|After 30 min at an initial air temperature (T_a) of 0°C, total thermal reinforcements and T_a were greater in ob/ob than lean mice; deep body temperature increased in both genotypes. Without a heater, body temperature in the ob/ob fell markedly in the cold.

3. 3.|Behavioural thermoregulation also depended on food intake and test temperature. i]4.|The capacity for behavioural thermoregulation is thus unimpaired in the ob/ob mouse, unlike that for autonomic thermoregulation, suggesting separate sets of central controls for the two thermoregulatory systems.

Expanding neurotransmitters in the hypothalamic neurocircuitry for energy balance regulation

The current epidemic of obesity and its associated metabolic syndromes impose unprecedented challenges to our society. Despite intensive research on obesity pathogenesis, an effective therapeutic strategy to treat and cure obesity is still lacking. Exciting studies in last decades have established the importance of the leptin neural pathway in the hypothalamus in the regulation of body weight homeostasis. Important hypothalamic neuropeptides have been identified as critical neurotransmitters from leptin-sensitive neurons to mediate leptin action. Recent research advance has significantly expanded the list of neurotransmitters involved in body weight-regulating neural pathways, including fast-acting neurotransmitters, gamma-aminobutyric acid (GABA) and glutamate. Given the limited knowledge on the leptin neural pathway for body weight homeostasis, understanding the function of neurotransmitters released from key neurons for energy balance regulation is essential for delineating leptin neural pathway and eventually for designing effective therapeutic drugs against the obesity epidemic.     

Feeding response to ghrelin agonist and antagonist in lean and obese Zucker rats

Ghrelin is a new orexigenic and adipogenic peptide primarily produced by the stomach and the hypothalamus. In the present experiment, we determined the circulating ghrelin levels in 60-week old fa/fa Zucker rats with a well-established obesity (n = 12) and in their lean (FA/FA) counterparts (n = 12). We also tested the feeding response of both groups to intra-peritoneal (I.P.) injection of ghrelin agonist and antagonist. Obese rats ate significantly more than the lean rats (21.7 +/- 1.1 vs. 18.3 +/- 0.3 g/day; p < 0.01). Their plasma ghrelin concentration was 35% higher than that in the lean homozygous rats (p < 0.025). GHRP-6 (1 mg/kg I.P, a GHS-R agonist) stimulated food intake in lean but not in obese rats (p < 0.01), whereas [D-Lys)]-GHRP-6 (12 mg/kg I.P., a GHS-R antagonist) decreased food intake in both groups (p < 0.0001). These results indicate that the obese Zucker rat is characterized by an increase in plasma ghrelin concentrations and by an attenuated response to a GHS-R agonist. They support a role for ghrelin in the development of obesity in the absence of leptin signaling.     

Loss of autophagy in hypothalamic POMC neurons impairs lipolysis

Autophagy degrades cytoplasmic contents to achieve cellular homeostasis. We show that selective loss of autophagy in hypothalamic proopiomelanocortin (POMC) neurons decreases α-melanocyte-stimulating hormone (MSH) levels, promoting adiposity, impairing lipolysis and altering glucose homeostasis. Ageing reduces hypothalamic autophagy and α-MSH levels, and aged-mice phenocopy, the adiposity and lipolytic defect observed in POMC neuron autophagy-null mice. Intraperitoneal isoproterenol restores lipolysis in both models, demonstrating normal adipocyte catecholamine responsiveness. We propose that an unconventional, autophagosome-mediated form of secretion in POMC neurons controls energy balance by regulating α-MSH production. Modulating hypothalamic autophagy might have implications for preventing obesity and metabolic syndrome of ageing.     

Growth hormone and ghrelin secretion in severely obese women before and after bariatric surgery

Objective: The objective was to evaluate ghrelin and growth hormone (GH) interactions and responses to a growth hormone‐releasing hormone (GHRH)/arginine test in severe obesity before and after surgically‐induced weight loss. Research Methods and Procedures: Our study population included 11 severely obese women 39 ± 12 years of age, with a mean BMI of 48.6 ± 2.4 kg/m², re‐studied in a phase of stabilized body weight, with a BMI of 33.4 ± 1.2 kg/m², 18 months after having successfully undergone biliopancreatic diversion (BPD). A GHRH/arginine test was performed before and 18 months after BPD to evaluate ghrelin and GH interactions. Active ghrelin, measured by radioimmunoassay (RIA), and GH, measured by chemiluminescence assay, were assayed before and after the GHRH/arginine test. Results: Fasting serum GH levels and GH area under the curve (AUC) significantly increased from 0.2 ± 0.05 ng/mL to 1 ± 0.3 ng/mL (p < 0.05) and from 514.76 ± 98.7 ng/mL for 120 minutes to 1957.3 ± 665.1 ng/mL for 120 minutes after bariatric surgery (p < 0.05), respectively. Although no significant change in fasting ghrelin levels was observed (573 ± 77.9 before BPD vs. 574.1 ± 32.7 after BPD), ghrelin AUC significantly increased from ?3253.9 ± 2180.9 pg/mL for 120 minutes to 1142.3 ± 916.4 pg/mL for 120 minutes after BPD (p < 0.05). Fasting serum insulin‐like growth factor (IGF)‐1 concentration did not change significantly (133.6 ± 9.9 ng/mL before vs. 153.3 ± 25.2 ng/mL after BPD). Discussion: Our study demonstrates that the mechanisms involved in ghrelin and GH secretion after the secretagogue stimulus (GHRH/arginine) are consistent with patterns observed in other populations.     

绵羊ghrelin基因表达的组织分布和发育性变化

选取2、30、60、90和120日龄的雄性哈萨克羊和新疆细毛羊各6只（无120日龄的哈萨克羊）,测体重后屠宰,采下丘脑、垂体、心脏、肝脏、瘤胃、网胃、瓣胃、皱胃、十二指肠、背最长肌,用RT-PCR和荧光实时定量PCR法检测ghrelin基因表达的组织分布,及其在皱胃中的发育性变化。研究结果表明：（1）品种内各生长时期的体重差异显著（P〈0．05）。雄性哈萨克羊和新疆细毛羊的体重在2日龄时无显著差异（P〉0．05）,30～90日龄间,前者的体重极显著高于后者（P〈0．01）;（2）所检测的各组织中都有ghrelin mRNA分布,但主要在皱胃中表达,其表达量远高于其他组织（P＜0．05）;（3）两品种绵羊皱胃ghrelin基因表达的发育性变化模式基本相似,都随着日龄的增加而呈上升趋势,其中雄性哈萨克羊的表达量在2～60日龄间持续上升,60日龄后趋于水平;雄性新疆细毛羊的表达量在2～90日龄间持续上升,90日龄后趋于水平。研究还发现雄性哈萨克羊皱胃胂relin基因的表达量在2～90日龄间极显著高于新疆细毛羊（P＜0．01）。     

Adaptive responses in hypothalamic neuropeptide Y in the face of prolonged high-fat feeding in the rat

While a dysregulation in neuropeptide Y (NPY) signaling has been described in rodent models of obesity, few studies have investigated the time-course of changes in NPY content and responsiveness during development of diet-induced obesity. Therefore we investigated the effect of differing lengths (2-17 weeks) of high-fat diet on hypothalamic NPY peptide content, release and NPY-induced hyperphagia. Male Sprague-Dawley rats (211 +/- 3 g) were fed either a high-fat diet (30% fat) or laboratory chow (5% fat). Animals were implanted with intracerebroventricular cannulae to investigate feeding responses to NPY (0.5 nmol, 1 nmol) after 4 or 12 weeks of diet. At the earlier stage of obesity, NPY-induced hyperphagia was not altered; however, animals maintained on the high-fat diet for the longer duration were hyper-responsive to NPY, compared to chow-fed control rats (p < 0.05). Overall, hypothalamic NPY peptide content tended to be decreased from 9 to 17 weeks of diet (p < 0.05). Total hypothalamic NPY content was negatively correlated with plasma leptin concentration (p < 0.05), suggesting the hypothalamic NPY system remains responsive to leptin's inhibitory signal. In addition, hypothalamic NPY overflow was significantly reduced in high-fat fed animals (p < 0.05). Together these results suggest a reduction in hypothalamic NPY activity in high-fat fed animals, perhaps in an attempt to restore energy balance.