Seminars in medicine of the Beth Israel Deaconess Medical Center. Neuroendocrine responses to starvation and weight loss

Evaluation of the anti-obesity effect of Sambucus nigra L. (elderberry) and Vitex agnus-castus L. (chasteberry) extracts in high-fat diet-induced obese rats

The aim of this study was to investigate the effects of S. nigra L. and V. agnus-castus L. plants on obesity in vivo. Extracts were prepared from S. nigra leaves, flowers, fruits and from V. agnus-castus leaves, flowers, and fruits using 100% water and 70% ethanol. The total phenol and flavonoid contents of the extracts were quantified spectrophotometrically. The findings revealed that the ethanol extracts of V. agnus-castus and S. nigra flowers had the highest phenolic content, while the ethanol extracts of S. nigra flowers and V. agnus-castus leaves had the highest flavonoid content. Qualification and quantification of the phenolic contents of the extracts were carried out using liquid chromatography-high resolution mass spectrometry (LC-HRMS) analyses. The study investigated the effects of various extracts on plasma levels of leptin, insulin, triiodothyronine (T3), thyroxine (T4), triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and lipase enzyme in obesity-induced rats. The results showed that the ethanol extract of V. agnus-castus flowers, as well as the ethanol and water extracts of V. agnus-castus leaves, resulted in body weight reduction in rats with obesity. Additionally, these extracts were found to decrease serum levels of LDL, triglycerides, leptin, lipase, TNF-α, and IL-1β while increasing levels of HDL and adiponectin. The LC-HRMS results demonstrated that all three extracts exhibited relatively high concentrations of luteolin-7-glycoside and kaempferol, in comparison to the other extracts. The ethanol extract of V. agnus-castus flowers contained 653.04 mg/100 g of luteolin-7-glycoside and 62.63 mg/100 g of kaempferol. The ethanol extract of V. agnus-castus leaves contained 1,720.26 mg/100 g of luteolin-7-glycoside and 95.85 mg/100 g of kaempferol. The water extract of V. agnus-castus leaves contained 690.49 mg/100 g of luteolin-7-glycoside and 194.41 mg/100 g of kaempferol. The study suggests that the ethanol extract of V. agnus-castus flowers and leaves, as well as the water extract of V. agnus-castus leaves, may have potential benefits in treating obesity. However, further controlled clinical studies are necessary to evaluate the clinical efficacy of V. agnus-castus in treating obesity and investigate the in vivo anti-obesogenic effects of luteolin-7-glycoside and kaempferol separately, both in their pure form and in combination.

Effects of Fasting on the Physiological and Psychological Responses in Middle-Aged Men

Tracking changes in the body during fasting takes into account indicators of mental well-being and physiological parameters. The aim of the study was to measure psychological and physiological reactions, along with their mutual relations, caused by 8 days of water-only fasting. Fourteen men aged 35 to 60 participated in the study, divided into two groups, younger and elder. In addition to physiological parameters, psychological data were collected using four different tests. The obtained results confirmed reduction in body weight, systolic blood pressure, resting diastolic blood pressure and glucose level, and increase in resting heart rate, cortisol and β-hydroxybutyrate concentration. However, no significant psychological changes were observed under the influence of fasting intervention. A significant interaction effect occurred for the state anxiety variable determined before and after the fasting intervention for both groups. Moreover, negative correlations between physiological (cortisol) and psychological factors of subjectively assessed stress were revealed. The only effect on cognitive ability was seen when responding to simple tasks. The study confirmed the beneficial effect of 8 days of water-only fasting on physiological variables without affecting mental well-being. The relatively high level of well-being after fasting intervention was independent of the physiological indicators of stress.

Primary cilia regulate adaptive responses to fasting

OBJECTIVE

Neuronal primary cilia are known to be a required organelle for energy balance and leptin action. However, whether primary cilia directly mediate adaptive responses during starvation is yet unknown. Therefore, we investigated the counterregulatory roles of primary cilia, and their related leptin action in energy-depleted condition.

METHOD

We generated leptin receptor (LepR) neuron-specific primary cilia knockout (Ift88 KO^LepR) mice. Leptin-mediated electrophysiological properties of the neurons in fasting condition were assessed using patch-clamp technique. Adaptive responses and neuroendocrine reflexes were measured by monitoring counterregulatory hormones.

RESULTS

In fasting state, the leptin-induced neuronal excitability and leptin homeostasis were impaired in Ift88 KO^LepR. In addition, the Ift88 KO^LepR exhibited aberrant fasting responses including lesser body weight loss, decreased energy expenditure, and lower heat generation compared to wild-type littermates. Furthermore, the primary cilia in LepR neurons are necessary for counterregulatory responses and leptin-mediated neuroendocrine adaptation to starvation.

CONCLUSION

Our results demonstrated that the neuronal primary cilia are crucial neuronal components mediating the adaptive counterregulatory responses to starvation.

Arcuate AgRP, but not POMC neurons, modulate paraventricular CRF synthesis and release in response to fasting

BACKGROUND

The activation of the hypothalamic-pituitary-adrenal (HPA) axis is essential for metabolic adaptation in response to fasting. However, the neurocircuitry connecting changes in the peripheral energy stores to the activity of hypothalamic paraventricular corticotrophin-releasing factor (CRF^PVN) neurons, the master controller of the HPA axis activity, is not completely understood. Our main goal was to determine if hypothalamic arcuate nucleus (ARC) POMC and AgRP neurons can communicate fasting-induced changes in peripheral energy stores, associated to a fall in plasma leptin levels, to CRF^PVN neurons to modulate the HPA axis activity in mice.

RESULTS

We observed increased plasma corticosterone levels associate with increased CRF^PVN mRNA expression and increased CRF^PVN neuronal activity in 36 h fasted mice. These responses were associated with a fall in plasma leptin levels and changes in the mRNA expression of Agrp and Pomc in the ARC. Fasting-induced decrease in plasma leptin partially modulated these responses through a change in the activity of ARC neurons. The chemogenetic activation of POMC^ARC by DREADDs did not affect fasting-induced activation of the HPA axis. DREADDs inhibition of AgRP^ARC neurons reduced the content of CRF^PVN and increased its accumulation in the median eminence but had no effect on corticosterone secretion induced by fasting.

CONCLUSION

Our data indicate that AgRP^ARC neurons are part of the neurocircuitry involved in the coupling of PVN^CRF activity to changes in peripheral energy stores induced by prolonged fasting.

The Infertility Trap: The Fertility Costs of Group-Living in Mammalian Social Evolution

Mammal social groups vary considerably in size from single individuals to very large herds. In some taxa, these groups are extremely stable, with at least some individuals being members of the same group throughout their lives; in other taxa, groups are unstable, with membership changing by the day. We argue that this variability in grouping patterns reflects a tradeoff between group size as a solution to environmental demands and the costs created by stress-induced infertility (creating an infertility trap). These costs are so steep that, all else equal, they will limit group size in mammals to ∼15 individuals. A species will only be able to live in larger groups if it evolves strategies that mitigate these costs. We suggest that mammals have opted for one of two solutions. One option (fission-fusion herding) is low cost but high risk; the other (bonded social groups) is risk-averse, but costly in terms of cognitive requirements.

Short-, Medium-, and Long-term Weight Changes and All-Cause Mortality in Old Age: Findings From the National Survey of the Japanese Elderly

BACKGROUND

Recent studies, predominantly in Western populations, suggest that both weight loss and weight gain are associated with an increased mortality risk in old age. However, evidence of this association in older Asian populations remains sparse. This study aimed to examine the association between weight change and all-cause mortality in a nationally representative sample of community-dwelling older Japanese people.

METHODS

Data were obtained from the National Survey of the Japanese Elderly, which included 4869 adults aged ≥60 years. Participants were followed for up to 30 years. We considered 3 indicators of weight change according to the follow-up interval: short-term (3 years), medium-term (6-7 years), and long-term (12-13 years). Weight change was classified as loss ≥ 5%, loss 2.5%-4.9%, stable (±2.4%), gain 2.5%-4.9%, and gain ≥ 5%. Cox proportional hazards models were used to calculate the relative mortality risk of each weight change category.

RESULTS

Weight loss ≥ 5% for all intervals was associated with higher mortality than stable weight and the effects were largely similar across all 3 intervals (hazard ratio [95% confidence interval]: 1.36 [1.22-1.51] for short-term, 1.36 [1.22-1.51] for medium-term, and 1.31 [1.11-1.54] for long-term). A similar pattern of results was observed among the young-old and old-old, and among men and women. The effect of weight loss on higher mortality was greater among those with a lower body mass index at baseline.

CONCLUSIONS

These findings could inform clinical and public health approaches to body-weight management aimed at improving the health and survival of older adults, particularly in Asian populations.

Increases in glucocorticoids are sufficient but not necessary to increase cooperative burrowing in Damaraland mole-rats

Despite widespread interest in the evolution of cooperative behaviour, the physiological mechanisms shaping their expression remain elusive. We tested the hypothesis that glucocorticoid (GC) hormones affect cooperative behaviour using captive Damaraland mole-rats (Fukomys damarensis), a cooperatively breeding mammal. Within groups, individuals routinely contribute to public goods that include foraging tunnels, which provide all group members access to the tubers of desert plants they feed on, communal food stores and nests. We found that experimental increases in glucocorticoid concentration (GCc) in non-breeding female helpers led them to be active for longer and to burrow more while active, raising their daily contributions to burrowing, but not food carrying or nest building. However, experimentally induced increases in burrowing did not lead to elevated GCc in helpers of both sexes. These results suggest that heightened GCc may stimulate some cooperative behaviours that are energetically demanding (a characteristic shared by many types of cooperative activities across species) but that the cooperative behaviours affected by GCc can also be regulated by other mechanisms.

Non-invasive hormone monitoring as a robust method for determining adrenocortical activity in injured, emaciated and oil-contaminated African penguins undergoing rehabilitation

Anthropogenic activity is a major driver of seabird injury and mortality in the 21st century. Although most seabirds perish within the natural environment as a result of human activities, some are rescued and admitted to rehabilitation centres. Despite the considerable number of admissions, little is known regarding the physiological response seabirds have to specific admission reasons and the rehabilitation process. In this study, we aimed to determine the effect of injury, emaciation, oiling, individual removal from the natural environment and the rehabilitation process on the physiological stress response of the African penguin (Spheniscus demersus). Urofaecal samples were collected from African penguins throughout a three-stage rehabilitation process and quantified for glucocorticoid metabolites (ufGCM). The three stages included an initial ICU crate stage (Stage 1), an ICU pen stage (Stage 2) and a rehabilitation stage (Stage 3). Data were analysed using a generalised linear model in order to determine the effect of admission reason, age and rehabilitation stage (Stage 1, 2 and 3) on ufGCM levels. Although the model indicated that only Stage 1 was a significant driver of adrenocortical activity in the study population, ufGCM levels of injured and emaciated animals within Stage 1 were considerably higher than those of birds with any other admission reason across all stages. This is the first study examining the causes and effect of rehabilitation on the physiological stress response in African penguins. Enhanced care and attention should be given to rescued individuals, especially during the first stage of rehabilitation, to reduce perception of additional stressors and thus increase the chance of full recovery.

Association between eating behavior, anthropometric and biochemical measurements, and peptide YY (PYY) hormone levels in obese adolescents in outpatient care

Objective To evaluate the eating behavior of obese adolescents and its association with biochemical, anthropometric and peptide YY (PYY) measures. Methods Fifty-one obese adolescents received counseling for weight management at 12 monthly appointments. Fasting serum PYY levels, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), insulin and glucose levels, waist circumference (WC) and results from the Three-Factor Eating Questionnaire (TFEQ-21) were assessed. Results Over one year there was a significant increase in PYY levels (p = 0.026), reduction in TC (p = 0.003), TG (p = 0.022), BMI (p = 0.002), BMI z-score (p < 0.001) and WC (p = 0.003). During this period there was a decrease in the uncontrolled eating score (UE), illustrating that adolescents displayed more self-control (p = 0.008) at the end of the study; however, this result was independent of BMI and BMI z-score (p = 0.407). The reduction in UE was associated with a significant improvement in insulin levels (rs = 0.326; p = 0.020). The reduction in UE was also associated with lower levels of blood glucose (r = 0.332; p = 0.017), and the increase of cognitive restriction, with the reduction of insulin insulin (rs = -0.294; p = 0.036) and TG (r = -0.368; p = 0.008) and an increase in Cognitive Restraint. Conclusions Our results show that after a year of monitoring weight loss, adolescents had more controlled eating behaviors, increased PYY levels, and reduced weights.

Effects of multiple cycles of weight loss and regain on the body weight regulatory system in rats

We studied the effects of multiple cycles of weight loss and regain on the defended body weight in rats. Thirty-six male Wistar rats were divided into three weight-matched groups: weight cyclers (n = 18), ad libitum-fed controls (n = 9), and maturity controls (n = 9). Cyclers underwent four rounds of 20% weight loss from 50% caloric restriction, each cycle followed by recovery to stable plateau weight on ad libitum feeding. Controls ate ad libitum. Maturity controls ate ad libitum and then weight cycled the final two rounds to evaluate the effect of age in later cycles. Cyclers' postdiet plateau weight became progressively lower than that of controls. With each weight loss, ghrelin increased, while insulin and leptin decreased; the magnitude of these changes did not differ across cycles. After four rounds, cyclers' weight (504 ± 7 vs. 540 ± 22 g; P < 0.05) and percent body fat (11.7 vs. 15.2%; P < 0.05) were lower than in controls. After a 4-mo follow-up period of ad libitum feeding, cyclers maintained a lower total fat-pad mass versus controls (8.6 ± 0.5 vs. 15.9 ± 3.6 g; P < 0.01) and a lower glucose area-under-the-curve on oral glucose tolerance tests (P < 0.05). Repeated weight-loss cycles exerted positive effects, durably lowering defended levels of body adiposity and improving glucose tolerance.

Fasting as a Therapy in Neurological Disease

Fasting is deeply entrenched in evolution, yet its potential applications to today’s most common, disabling neurological diseases remain relatively unexplored. Fasting induces an altered metabolic state that optimizes neuron bioenergetics, plasticity, and resilience in a way that may counteract a broad array of neurological disorders. In both animals and humans, fasting prevents and treats the metabolic syndrome, a major risk factor for many neurological diseases. In animals, fasting probably prevents the formation of tumors, possibly treats established tumors, and improves tumor responses to chemotherapy. In human cancers, including cancers that involve the brain, fasting ameliorates chemotherapy-related adverse effects and may protect normal cells from chemotherapy. Fasting improves cognition, stalls age-related cognitive decline, usually slows neurodegeneration, reduces brain damage and enhances functional recovery after stroke, and mitigates the pathological and clinical features of epilepsy and multiple sclerosis in animal models. Primarily due to a lack of research, the evidence supporting fasting as a treatment in human neurological disorders, including neurodegeneration, stroke, epilepsy, and multiple sclerosis, is indirect or non-existent. Given the strength of the animal evidence, many exciting discoveries may lie ahead, awaiting future investigations into the viability of fasting as a therapy in neurological disease.

Association Between Serum Leptin Level and Calcific Aortic Valve Disease

Background The pathophysiological process of calcific aortic valve disease (CAVD) is similar to that of atherosclerosis. Leptin accelerates the process of atherosclerosis. We sought to examine the relationship between leptin and CAVD. Methods and Results Serum leptin was measured in 397 consecutive patients undergoing standard transthoracic echocardiography and Doppler flow imaging. Multiple logistic regression analyses were used to assess the association between leptin and CAVD. Western blotting was performed to detect the expression of phosphorylated and total extracellular signal-regulated kinase. Serum leptin (median) was higher in 200 patients with CAVD than that in 197 non-CAVD controls (20.07 versus 9.03 ng/mL; P<0.01). Leptin correlated positively with age (r=0.37, P<0.01) and negatively with estimated glomerular filtration rate (r=-0.37, P<0.01). Multivariate analysis indicated that elevated leptin was an independent determinant for the presence of CAVD (P<0.01). Receiver-operating characteristic curve analysis of leptin to detect the presence of CAVD showed that the area under the curve was 0.74 (95% CI, 0.69-0.79; P<0.01). The diagnostic value of leptin for the detection of CAVD was higher among younger patients (aged ≤65 years) or those with at least mildly reduced renal function (estimated glomerular filtration rate ≤82.06 mL/min per 1.73 m²). The activation of extracellular signal-regulated kinase 1/2 was stronger in calcific aortic valves than in normal aortic valves. Conclusions Elevated leptin is associated with the presence of CAVD, especially among younger patients or those with renal dysfunction.

Social structure as a strategy to mitigate the costs of group living: a comparison of gelada and guereza monkeys

In mammals, and especially primates, group size and social complexity are typically correlated. However, we have no general explanation why this is so. I suggest that the answer may lie in one of the costs of group living: mammalian reproductive endocrinology is extremely sensitive to stress, and forms one of the hidden costs of living in groups. Fertility declines with group size widely across the social mammals, including primates, and will ultimately place a constraint on group size. However, some species seem to have been able to mitigate this cost by forming bonded relationships that reduce the impact of experienced aggression, even if rates of aggression remain high. The downside is that they reduce network connectivity and hence risk fragmenting the group by providing fracture lines for group fission. To explore this, I compare network indices and fertility patterns across the same range of group sizes for two species of Old World monkeys, Colobus guereza and Theropithecus gelada: the former relatively unsocial, the latter intensely social with frequent use of grooming-based alliances. Compared to those of the guereza, gelada social networks lose density more slowly, maintain connectedness more effectively and are less likely to fragment as they increase in size. Although fertility declines with group size in both species, in gelada the impact of this effect is deferred to larger group sizes. The differences in fertility and network structure both predict the very different maximum group sizes typical of these two species, as well as the typical sizes at which their groups undergo fission. This finding may explain aspects of wider mammalian sociality.

Fenofibrate prevents skeletal muscle loss in mice with lung cancer

The cancer anorexia cachexia syndrome is a systemic metabolic disorder characterized by the catabolism of stored nutrients in skeletal muscle and adipose tissue that is particularly prevalent in nonsmall cell lung cancer (NSCLC). Loss of skeletal muscle results in functional impairments and increased mortality. The aim of the present study was to characterize the changes in systemic metabolism in a genetically engineered mouse model of NSCLC. We show that a portion of these animals develop loss of skeletal muscle, loss of adipose tissue, and increased inflammatory markers mirroring the human cachexia syndrome. Using noncachexic and fasted animals as controls, we report a unique cachexia metabolite phenotype that includes the loss of peroxisome proliferator-activated receptor-α (PPARα) -dependent ketone production by the liver. In this setting, glucocorticoid levels rise and correlate with skeletal muscle degradation and hepatic markers of gluconeogenesis. Restoring ketone production using the PPARα agonist, fenofibrate, prevents the loss of skeletal muscle mass and body weight. These results demonstrate how targeting hepatic metabolism can prevent muscle wasting in lung cancer, and provide evidence for a therapeutic strategy.

Heterogeneity in Trajectories of Body Mass Index and Their Associations with Mortality in Old Age: A Literature Review

This article reviewed studies to investigate the association between trajectories of body mass index (BMI) and mortality among older adults. Investigators conducted a systematic search of published peer-reviewed literature in the PubMed database, and three articles that satisfied the inclusion criteria for the review were identified. All of these studies used group-based trajectory models to identify distinct BMI trajectories. Two studies were derived from the U.S. and used data from the Health and Retirement Study, with up to nine repeated observations. Most of the BMI trajectories in older Americans were increasing and fell primarily within the overweight and obese ranges. The other study was from Japan and used nationwide data, with up to seven repeated observations. BMI trajectories identified in the older Japanese were mostly decreasing and fell primarily within the normal weight range. Although the distribution of BMI trajectories was different between the two nations, the findings from these three studies consistently demonstrated that people with stable overweight trajectories had the lowest all-cause mortality rates in both countries. Beyond this, however, these studies suggested that priorities for weight control in old age should likely differ between Western and non-Western countries. Research regarding BMI trajectories and mortality in old age is very limited at present. Evidence from countries other than the U.S. and Japan is warranted in order to validate current findings and guide the development of local clinical and public health strategies for body weight management aimed at improving the health and survival of older adults.

Increased ghrelin signaling prolongs survival in mouse models of human aging through activation of sirtuin1

Caloric restriction (CR) is known to retard aging and delay functional decline as well as the onset of diseases in most organisms. Ghrelin is secreted from the stomach in response to CR and regulates energy metabolism. We hypothesized that in CR ghrelin has a role in protecting aging-related diseases. We examined the physiological mechanisms underlying the ghrelin system during the aging process in three mouse strains with different genetic and biochemical backgrounds as animal models of accelerated or normal human aging. The elevated plasma ghrelin concentration was observed in both klotho-deficient and senescence-accelerated mouse prone/8 (SAMP8) mice. Ghrelin treatment failed to stimulate appetite and prolong survival in klotho-deficient mice, suggesting the existence of ghrelin resistance in the process of aging. However, ghrelin antagonist hastened death and ghrelin signaling potentiators rikkunshito and atractylodin ameliorated several age-related diseases with decreased microglial activation in the brain and prolonged survival in klotho-deficient, SAMP8 and aged ICR mice. In vitro experiments, the elevated sirtuin1 (SIRT1) activity and protein expression through the cAMP-CREB pathway was observed after ghrelin and ghrelin potentiator treatment in ghrelin receptor 1a-expressing cells and human umbilical vein endothelial cells. Furthermore, rikkunshito increased hypothalamic SIRT1 activity and SIRT1 protein expression of the heart in the all three mouse models of aging. Pericarditis, myocardial calcification and atrophy of myocardial and muscle fiber were improved by treatment with rikkunshito. Ghrelin signaling may represent one of the mechanisms activated by CR, and potentiating ghrelin signaling may be useful to extend health and lifespan.

Energetic stress: The reciprocal relationship between energy availability and the stress response

The worldwide epidemic of metabolic syndromes and the recognized burden of mental health disorders have driven increased research into the relationship between the two. A maladaptive stress response is implicated in both mental health disorders and metabolic disorders, implicating the hypothalamic-pituitary-adrenal (HPA) axis as a key mediator of this relationship. This review explores how an altered energetic state, such as hyper- or hypoglycemia, as may be manifested in obesity or diabetes, affects the stress response and the HPA axis in particular. We propose that changes in energetic state or energetic demands can result in "energetic stress" that can, if prolonged, lead to a dysfunctional stress response. In this review, we summarize the role of the hypothalamus in modulating energy homeostasis and then briefly discuss the relationship between metabolism and stress-induced activation of the HPA axis. Next, we examine seven mechanisms whereby energetic stress interacts with neuroendocrine stress response systems, including by glucocorticoid signaling both within and beyond the HPA axis; by nutrient-induced changes in glucocorticoid signaling; by impacting the sympathetic nervous system; through changes in other neuroendocrine factors; by inducing inflammatory changes; and by altering the gut-brain axis. Recognizing these effects of energetic stress can drive novel therapies and prevention strategies for mental health disorders, including dietary intervention, probiotics, and even fecal transplant.

Maternal stress and diet may influence affective behavior and stress-response in offspring via epigenetic regulation of central peptidergic function

It has been shown that maternal stress and malnutrition, or experience of other adverse events, during the perinatal period may alter susceptibility in the adult offspring in a time-of-exposure dependent manner. The mechanism underlying this may be epigenetic in nature. Here, we summarize some recent findings on the effects on gene-regulation following maternal malnutrition, focusing on epigenetic regulation of peptidergic activity. Numerous neuropeptides within the central nervous system are crucial components in regulation of homeostatic energy-balance, as well as affective health (i.e. health events related to affective disorders, psychiatric disorders also referred to as mood disorders). It is becoming evident that expression, and function, of these neuropeptides can be regulated via epigenetic mechanisms during fetal development, thereby contributing to the development of the adult phenotype and, possibly, modulating disease susceptibility. Here, we focus on two such neuropeptides, neuropeptide Y (NPY) and corticotropin-releasing hormone (CRH), both involved in regulation of endocrine function, energy homeostasis, as well as affective health. While a number of published studies indicate the involvement of epigenetic mechanisms in CRH-dependent regulation of the offspring adult phenotype, NPY has been much less studied in this context and needs further work.

Food intake and appetite control in a GH-transgenic zebrafish

The biological actions of growth hormone (GH) are pleiotropic, including growth promotion, energy mobilization, gonadal development, appetite, and social behavior. The regulatory network for GH is complex and includes many central and peripheral endocrine factors as well as that from the environment. It is known that GH transgenesis results in increased growth, food intake, and consequent metabolic rates in fishes. However, the manner in which GH transgenesis alters the energetic metabolism in fishes has not been well explored. In order to elucidate these consequences, we examined the effect of GH overexpression on appetite control mechanisms in a transgenic zebrafish (Danio rerio) model. To this, we analyzed feeding behavior and the expression of the main appetite-related genes in two different feeding periods (fed and fasting) in non-transgenic (NT) and transgenic (T) zebrafish as well as glycaemic parameters of them. Our initial results have shown that NT males and females present the same feeding behavior and expression of main appetite-controlling genes; therefore, the data of both sexes were properly grouped. Following grouped data analyses, we compared the same parameters in NT and T animals. Feeding behavior results have shown that T animals eat significantly more and faster than NT siblings. Gene expression results pointed out that gastrointestinal (GT) cholecystokinin has a substantial contribution to the communication between peripheral and central control of food intake. Brain genes expression analyses revealed that T animals have a down-regulation of two strong and opposite peptides related to food intake: the anorexigenic proopiomelanocortin (pomc) and the orexigenic neuropeptide Y (npy). The down-regulation of pomc in T when compared with NT is an expected result, since the decrease in an anorexigenic factor might keep the transgenic fish hungry. The down-regulation of npy seemed to be contradictory at first, but if we consider the GH's capacity to elevate blood glucose, and that NPY is able to respond to humoral factors like glucose, this down-regulation makes sense. In fact, our last experiment showed that transgenics presented elevated blood glucose levels, confirming that npy might responded to this humoral factor. In conclusion, we have shown that GT responds to feeding status without interference of transgenesis, whereas brain responds to GH transgenesis without any effect of treatment. It is clear that transgenic zebrafish eat more and faster, and it seems that it occurs due to pomc down-regulation, since npy might be under regulation of the humoral factor glucose.

Trajectories of Body Mass Index and Their Associations With Mortality Among Older Japanese: Do They Differ From Those of Western Populations?

Few studies have focused on the relationship between the trajectories of long-term changes in body mass index (BMI; weight (kg)/height (m)(2)) and all-cause mortality in old age, particularly in non-Western populations. We evaluated this association by applying group-based mixture models to data derived from the National Survey of the Japanese Elderly, which included 4,869 adults aged 60 or more years, with up to 7 repeated observations between 1987 and 2006. Four distinct BMI trajectories were identified: "low-normal weight, decreasing" (baseline BMI = 18.7; 23.8% of sample); "mid-normal weight, decreasing" (baseline BMI = 21.9; 44.6% of sample); "high-normal weight, decreasing" (baseline BMI = 24.8; 26.5% of sample); and "overweight, stable" (baseline BMI = 28.7; 5.2% of sample). Survival analysis with an average follow-up of 13.8 years showed that trajectories of higher BMI were associated with lower mortality. In particular, relative to those with a mid-normal weight, decreasing BMI trajectory, those with an overweight, stable BMI trajectory had the lowest mortality, and those with a low-normal, decreasing BMI trajectory had the highest mortality. In sharp contrast with prior observations from Western populations, BMI changes lie primarily within the normal-weight range, and virtually no older Japanese are obese. The association between BMI trajectories and mortality varies according to the distribution of BMI within the population.

Rikkunshito, a ghrelin potentiator, ameliorates anorexia-cachexia syndrome

Anorexia–cachexia syndrome develops during the advanced stages of various chronic diseases in which patients exhibit a decreased food intake, weight loss, and muscle tissue wasting. For these patients, this syndrome is a critical problem leading to an increased rate of morbidity and mortality. The present pharmacological therapies for treating anorexia–cachexia have limited effectiveness. The Japanese herbal medicine rikkunshito is often prescribed for the treatment of anorexia and upper gastrointestinal (GI) disorders. Thus, rikkunshito is expected to be beneficial for the treatment of patients with anorexia–cachexia syndrome. In this review, we summarize the effects of rikkunshito and its mechanisms of action on anorexia–cachexia. Persistent loss of appetite leads to a progressive depletion of body energy stores, which is frequently associated with cachexia. Consequently, regulating appetite and energy homeostasis is critically important for treating cachexia. Ghrelin is mainly secreted from the stomach, and it plays an important role in initiating feeding, controlling GI motility, and regulating energy expenditure. Recent clinical and basic science studies have demonstrated that the critical mechanism of rikkunshito underlies endogenous ghrelin activity. Interestingly, several components of rikkunshito target multiple gastric and central sites, and regulate the secretion, receptor sensitization, and degradation of ghrelin. Rikkunshito is effective for the treatment of anorexia, body weight loss, muscle wasting, and anxiety-related behavior. Furthermore, treatment with rikkunshito was observed to prolong survival in an animal model of cachexia. The use of a potentiator of ghrelin signaling, such as rikkunshito, may represent a novel approach for the treatment of anorexia–cachexia syndrome.

Changes in post-prandial glucose and pancreatic hormones, and steady-state insulin and free fatty acids after gastric bypass surgery

BACKGROUND

Changes in the multiple mechanisms that regulate glucose metabolism after gastric bypass (RYGB) are still being unveiled. The objective of this study was to compare the changes of glucose and pancreatic hormones [C-peptide, glucagon, and pancreatic polypeptide (PP)] during a meal tolerance test (MTT) and steady-state insulin and free fatty acid (FFA) concentrations during euglycemic-hyperinsulinemic clamp 14 days and 6 months after RYGB in morbidly obese nondiabetic patients.

METHODS

Two groups were studied at baseline and at 14 days: the RYGB followed by caloric restriction group (RYGB, n = 12) and the equivalent caloric restriction alone group (Diet, n = 10), to control for energy intake and weight loss. The RYGB group was studied again at 6 months to assess the changes after substantial weight loss. During MTT, the early and overall changes in glucose and pancreatic hormone concentrations were determined, and during the clamp, steady-state insulin and FFA concentrations were assessed.

RESULTS

After 14 days, RYGB patients had enhanced postprandial glucose, C-peptide, and glucagon responses, and decreased postprandial PP concentrations. Steady-state insulin concentrations were decreased at 14 days only in RYGB patients, and FFA increased in both groups. Six months after RYGB and substantial weight loss, the decrease in insulin concentrations during clamp persisted, and there were further changes in postprandial glucose and glucagon responses. FFA concentrations during clamp were significantly lower at 6 months, relative to presurgical values.

CONCLUSIONS

In morbidly obese nondiabetic patients, RYGB produces early changes in postmeal glucose, C-peptide, glucagon, and PP responses, and it appears to enhance insulin clearance early after RYGB and improve insulin sensitivity in adipose tissue at 6 months postsurgery. The early changes cannot be explained by caloric restriction alone.

Metabolic and psychological response to 7-day fasting in obese patients with and without metabolic syndrome

BACKGROUND

Extended modified fasting is a frequently practiced tradition in Europe. It is claimed to improve the cardiometabolic state and physical and psychological well-being by an evolutionary co-developed adaptation response. We aimed to investigate the cardiometabolic and psychological effects of a 7-day fast and differences of these responses between patients with or without metabolic syndrome (MetS).

METHODS

We investigated 30 female subjects (49.0 ± 8.1 years, BMI 30.4 ± 6.7 kg/m(2)) with (n = 12) and without (n = 18) MetS. All subjects participated in a 7-day fast according to Buchinger with a nutritional energy intake of 300 kcal/day and stepwise reintroduction of solid food thereafter. Outcomes were assessed baseline and after fasting and included measures of metabolic and glucoregulatory control, adipokines as well as psychological well-being as assessed by Profile of Mood States (POMS) and Hospital Anxiety and Depression Scale (HADS).

RESULTS

Mean weight decreased from 85.4 ± 18.8 kg to 79.7 ± 18.2 kg accompanied by systolic/diastolic blood pressure (BP) reduction of -16.2 mm Hg (95% CI: -9.1; -23.3 mm Hg) and -6.0 mm Hg (95% CI: -1.8; -10.3 mm Hg), each p < 0.001 and p = 0.005. Fasting led to marked decreases of levels of LDL-cholesterol, leptin, and insulin and increases of levels of adiponectin, leptin receptors, and resistin. Fasting-induced mood enhancement was reflected by decreased anxiety, depression, fatigue, and improved vigor. Patients with MetS showed some greater changes in B P, LDL-cholesterol, triglycerides, adiponectin, leptin, and sleep quality. Fasting was well-tolerated.

CONCLUSIONS

Our results point to marked beneficial responses to 7-day modified fasting and a potential role in the prevention of the MetS. Randomized trials with longer observation periods should test the clinical effectiveness of fasting in metabolic diseases.

Nutritional rehabilitation after ICU - does it happen: a qualitative interview and observational study

AIMS AND OBJECTIVES

To compare and contrast current nutritional rehabilitation practices against recommendations from National Institute for Health and Excellence guideline Rehabilitation after critical illness (NICE) (2009, http://www.nice.org.uk/cg83).

BACKGROUND

Recovery from critical illness has gained increasing prominence over the last decade but there is remarkably little research relating to nutritional rehabilitation.

DESIGN

The study is a qualitative study based on patient interviews and observations of ward practice.

METHODS

Seventeen patients were recruited into the study at discharge from the intensive care unit (ICU) of a large teaching hospital in central Scotland in 2011. Semi-structured interviews were conducted on transfer to the ward and weekly thereafter. Fourteen of these patients were followed up at three months post-ICU discharge, and a semi-structured interview was carried out. Observations of ward practice were carried out twice weekly for the duration of the ward stay.

RESULTS

Current nutritional practice for post-intensive care patients did not reflect the recommendations from the NICE guideline. A number of organisational issues were identified as influencing nutritional care. These issues were categorised as ward culture, service-centred delivery of care and disjointed discharge planning. Their influence on nutritional care was compounded by the complex problems associated with critical illness.

CONCLUSIONS

The NICE guideline provides few nutrition-specific recommendations for rehabilitation; however, current practice does not reflect the nutritional recommendations that are detailed in the rehabilitation care pathway.

RELEVANCE TO CLINICAL PRACTICE

Nutritional care of post-ICU patients is problematic and strategies to overcome these issues need to be addressed in order to improve nutritional intake.

Adaptive reciprocity of lipid and glucose metabolism in human short-term starvation

The human organism has tools to cope with metabolic challenges like starvation that are crucial for survival. Lipolysis, lipid oxidation, ketone body synthesis, tailored endogenous glucose production and uptake, and decreased glucose oxidation serve to protect against excessive erosion of protein mass, which is the predominant supplier of carbon chains for synthesis of newly formed glucose. The starvation response shows that the adaptation to energy deficit is very effective and coordinated with different adaptations in different organs. From an evolutionary perspective, this lipid-induced effect on glucose oxidation and uptake is very strong and may therefore help to understand why insulin resistance in obesity and type 2 diabetes mellitus is difficult to treat. The importance of reciprocity in lipid and glucose metabolism during human starvation should be taken into account when studying lipid and glucose metabolism in general and in pathophysiological conditions in particular.

Attenuation of Zn-induced hyperleptinemia/leptin resistance in Wistar rat after feeding modified poultry egg

BACKGROUND

The prevalence of obesity is increasing exponentially world over. Leptin resistance/hyperleptinemia is attributed to its cause in majority of the obese humans where mutation in genetic component or ob gene has not been found operative. The generation of oxidative stress was suggested as its cause. In our previous study, we have reported that the inclusion of antioxidant enriched modified poultry egg (ME) in diet reversed the ionic imbalance and ameliorated the oxidative stress caused by excessive Zn in diet. In the present study, the efficacy of ME verses conventional egg (CE) was tested on Zn-induced leptin resistance in rat model to ascertain if the supplementation of antioxidants in the form of egg can reverse Zn-induced leptin resistance to leptin sensitive state.

METHODS

Hyperleptinemia was induced in rats by feeding them Zn-supplemented hyperleptinemic diets-I and II (Zn-HL-Diet) for 2 months. Thereafter, half of them were fed either on CE or ME mixed Zn-HL-diets I and II for another two months. The data was analyzed applying one way Anova and Tukey's HSD post hoc test.

RESULTS

The results revealed that food intake, gain in body weight, height and number/unit surface area of intestinal microvillus and serum leptin, glucose, insulin and cortisol were higher in CE and Zn-HL-Diet treated groups; serum Zn, Cu, Mg were higher and Cu and Mg in tissues were lower in them than the control group. In ME treated groups, these parameters were lower and were close to the control group. These changes resulted from the restoration of ionic balance of Zn, Cu and Mg in the blood serum and tissues including liver and hair in ME treated rats.

CONCLUSION

The data suggest that Zn-induced leptin resistance can be attenuated through restoring the ionic balance of Zn, Cu and Mg through inclusion of antioxidants in diet such as these modified eggs. But further clinical studies are required before they are put to use for human consumption.

All bariatric surgeries are not created equal: insights from mechanistic comparisons

Despite considerable scientific progress on the biological systems that regulate energy balance, we have made precious little headway in providing new treatments to curb the obesity epidemic. Diet and exercise are the most popular treatment options for obesity, but rarely are they sufficient to produce long-term weight loss. Bariatric surgery, on the other hand, results in dramatic, sustained weight loss and for this reason has gained increasing popularity as a treatment modality for obesity. At least some surgical approaches also reduce obesity-related comorbidities including type 2 diabetes and hyperlipidemia. This success puts a premium on understanding how these surgeries exert their effects. This review focuses on the growing human and animal model literature addressing the underlying mechanisms. We compare three common procedures: Roux-en-Y Gastric Bypass (RYGB), vertical sleeve gastrectomy (VSG), and adjustable gastric banding (AGB). Although many would group together VSG and AGB as restrictive procedures of the stomach, VSG is more like RYGB than AGB in its effects on a host of endpoints including intake, food choice, glucose regulation, lipids and gut hormone secretion. Our strong belief is that to advance our understanding of these procedures, it is necessary to group bariatric procedures not on the basis of surgical similarity but rather on how they affect key physiological variables. This will allow for greater mechanistic insight into how bariatric surgery works, making it possible to help patients better choose the best possible procedure and to develop new therapeutic strategies that can help a larger portion of the obese population.

Fasting of 3-day-old chicks leads to changes in histone H3 methylation status

Unfavorable nutritional conditions during early developmental periods may cause neuronal network remodeling in the hypothalamus, which influences subsequent adaptability to those same stressful conditions. Alterations in hypothalamic plasticity as a result of neuronal remodeling are achieved by variations in the repertoire of proteins expressed via gene transcriptional activation or repression, both of which are modulated by histone methylation status. This study demonstrates that fasting had a stimulatory effect on dimethylation and trimethylation of histone 3 at lysine 27 (H3K27) in preoptic/anterior hypothalamus (PO/AH) of 3-day-old chicks. The expression of enhancer of zeste 2 (EZH2), a H3K27-specific histone methyltransferase (HMT), was significantly increased by fasting in the paraventricular nucleus (PVN) and PO/AH, which is consistent with the upregulation of H3K27 dimethylation and trimethylation. Furthermore, in the PVN, corticotrophin-releasing hormone (CRH) mRNA expression was significantly inhibited, while mRNA expressions of thyrotropin-releasing hormone (TRH) and type 2 deiodinase (D2) were significantly stimulated by fasting. These findings highlight the potential role of H3K27 methylation status in early feed stress responses in chicks and may be indicative of an epigenetic mechanism for later adaptation to feed intake stress.

Ghrelin is an orexigenic peptide and elicits anxiety-like behaviors following administration into discrete regions of the hypothalamus

Previous evidence indicates that peripherally administered ghrelin significantly increases corticotropin releasing hormone (CRH) mRNA and serum corticosterone. In addition, intraventricular administration of ghrelin has been reported to elicit anxiety-like behaviors suggesting that the peptide plays a role in mediating neuroendocrine and behavioral responses to stress. In the present study, we characterized the orexigenic, metabolic, and anxiogenic actions of ghrelin following microinjection into the arcuate nucleus (ARN), paraventricular nucleus (PVN), perifornical hypothalamus (PFH), and ventromedial nucleus (VMN). To assess ghrelin's role in anxiogenic behavior, rats were injected with vehicle or 50-800pmol of ghrelin and then placed in an elevated plus maze (EPM) for 10min. Each test was performed as a single trial per animal. In separate behavioral testing we measured the induction of stereotypic behaviors. Doses of 200pmol or higher administered into the ARN and PVN elicited anxiety-like behaviors, including an increased avoidance of the open arms of the EPM. However, in the PFH and VMN, higher doses of ghrelin (400-800pmol) were required to induce anxiety. Ghrelin doses as low as 50pmol stimulated eating and altered energy substrate oxidation (respiratory quotient; RQ) when injected into the ARN and PVN. Injections into the PFH and VMN elicited more modest effects on eating and RQ at doses of 400pmol or greater. Our findings indicate that regions of the hypothalamus appear to be differentially sensitive and responsive to the feeding-stimulant, metabolic, and anxiogenic actions of ghrelin and that the ARN and PVN, in particular, exert a primary role in mediating these effects.

Potentiation of ghrelin signaling attenuates cancer anorexia-cachexia and prolongs survival

Cancer anorexia-cachexia syndrome is characterized by decreased food intake, weight loss, muscle tissue wasting and psychological distress, and this syndrome is a major source of increased morbidity and mortality in cancer patients. This study aimed to clarify the gut-brain peptides involved in the pathogenesis of the syndrome and determine effective treatment for cancer anorexia-cachexia. We show that both ghrelin insufficiency and resistance were observed in tumor-bearing rats. Corticotropin-releasing factor (CRF) decreased the plasma level of acyl ghrelin, and its receptor antagonist, α-helical CRF, increased food intake of these rats. The serotonin 2c receptor (5-HT2cR) antagonist SB242084 decreased hypothalamic CRF level and improved anorexia, gastrointestinal (GI) dysmotility and body weight loss. The ghrelin receptor antagonist (D-Lys3)-GHRP-6 worsened anorexia and hastened death in tumor-bearing rats. Ghrelin attenuated anorexia-cachexia in the short term, but failed to prolong survival, as did SB242084 administration. In addition, the herbal medicine rikkunshito improved anorexia, GI dysmotility, muscle wasting, and anxiety-related behavior and prolonged survival in animals and patients with cancer. The appetite-stimulating effect of rikkunshito was blocked by (D-Lys3)-GHRP-6. Active components of rikkunshito, hesperidin and atractylodin, potentiated ghrelin secretion and receptor signaling, respectively, and atractylodin prolonged survival in tumor-bearing rats. Our study demonstrates that the integrated mechanism underlying cancer anorexia-cachexia involves lowered ghrelin signaling due to excessive hypothalamic interactions of 5-HT with CRF through the 5-HT2cR. Potentiation of ghrelin receptor signaling may be an attractive treatment for anorexia, muscle wasting and prolong survival in patients with cancer anorexia-cachexia.

Cachexia, malnutrition, the refeeding syndrome, and lessons from Goldilocks

Cachexia has plagued clinicians for centuries. Although all cachexia is related to malnutrition, cachexia associated with malignant diseases differs from starvation cachexia in that it is more recalcitrant to nutritional therapy. All cachexia responds to judicious nutritional support; however, cancer cachexia worsens autonomously as the disease advances and cannot be arrested or reversed by any known form of nutrition, hormonal, or pharmacologic therapy. Cachexia must be treated cautiously to avoid overfeeding syndrome, which may result in serious or dangerous complications or death.

Neurobiology of overeating and obesity: the role of melanocortins and beyond

The alarming increase in the incidence of obesity and obesity-associated disorders makes the etiology of obesity a widely studied topic today. As opposed to 'homeostatic feeding', where food intake is restricted to satisfy one's biological needs, the term 'non-homeostatic' feeding refers to eating for pleasure or the trend to over-consume (palatable) food. Overconsumption is considered a crucial factor in the development of obesity. Exaggerated consumption of (palatable) food, coupled to a loss of control over food intake despite awareness of its negative consequences, suggests that overeating may be a form of addiction. At a molecular level, insulin and leptin resistance are hallmarks of obesity. In this review, we specifically address the question how leptin resistance contributes to enhanced craving for (palatable) food. Since dopamine is a key player in the motivation for food, the interconnection between dopamine, leptin and neuropeptides related to feeding will be discussed. Understanding the mechanisms by which these neuropeptidergic systems hijack the homeostatic feeding mechanisms, thus leading to overeating and obesity is the primary aim of this review. The melanocortin system, one of the crucial neuropeptidergic systems modulating feeding behavior will be extensively discussed. The inter-relationship between neuronal populations in the arcuate nucleus and other areas regulating energy homeostasis (lateral hypothalamus, paraventricular nucleus, ventromedial hypothalamus etc.) and reward circuitry (the ventral tegmental area and nucleus accumbens) will be evaluated and scrutinized.

Prolonged fasting as a method of mood enhancement in chronic pain syndromes: a review of clinical evidence and mechanisms

Periods of deliberate fasting with restriction to intake of solid food are practiced worldwide, mostly based on a traditional, cultural, or religious background. Recent evidence from clinical trials shows that medically supervised modified fasting (200-500 kcal nutritional intake/day) with periods from 7 to 21 days is efficacious in the treatment of rheumatic diseases and chronic pain syndromes. Here, fasting is frequently accompanied by increased alertness and mood enhancement. The beneficial claims of fasting are supported by experimental research, which has found fasting to be associated with increased brain availability of serotonin, endogenous opioids, and endocannabinoids. Fasting-induced neuroendocrine activation and mild cellular stress response with increased production of neurotrophic factors may also contribute to the mood enhancement of fasting. Fasting treatments may be useful as an adjunctive therapeutic approach in chronic pain patients. The mood-enhancing and pain-relieving effect of therapeutic fasting should be further evaluated in randomized clinical trials.

Type 2 diabetes, cardiovascular disease, and the evolutionary paradox of the polycystic ovary syndrome: a fertility first hypothesis

Worldwide, the high prevalence of the Polycystic Ovary Syndrome (PCOS), a heritable cause of ovarian infertility, is an evolutionary paradox, which provides insight into the susceptibility of well-fed human populations to cardiovascular disease and diabetes. We propose that PCOS, Type 2 diabetes (T2D) and the Metabolic Syndrome are modern phenotypic expressions of a metabolic genotype attuned to the dietary and energetic conditions of the Pleistocene. This metabolic "Fertility First" rather than "Thrifty" genotype persisted at high prevalence throughout the entire agrarian period-from around 12,000 years ago until 1800 AD-primarily, we contend, because it conferred a fertility advantage in an environment defined by chronic and often severe seasonal food shortage. Conversely, we argue that genetic adaptations to a high carbohydrate, low protein agrarian diet, with increased sensitivity to insulin action, were constrained because these adaptations compromised fertility by raising the lower bound of body weight and energy intake optimal for ovulation and reproduction. After 1800, the progressive attainment of dietary energy sufficiency released human populations from this constraint. This release, through the powerful mechanism of fertility selection, increased, in decades rather than centuries, the prevalence of a genotype better suited to carbohydrate metabolism. This putative mechanism for rapid and recent human evolution can explain the lower susceptibility to T2D of today's Europid populations. This hypothesis predicts that the increasing rates of diabetes and cardiovascular disease, which typically accompany economic development, will be tempered by natural, but particularly fertility, selection against the conserved ancestral genotypes that currently underpin them.

Serum leptin levels and irritable bowel syndrome: a new hypothesis

GOALS

This study was undertaken to investigate the relationship between serum leptin levels and the development irritable bowel syndrome (IBS).

BACKGROUND

Stress has been known as an important causative factor in IBS. Various studies have indicated the relationship between serum leptin levels and stress levels. So searching the relationship between the production and level of this hormone and development of IBS may help to understand the pathophysiology of the disease.

STUDY

This was a case-control study. Eighty IBS patient and 80 controls were recruited. All participants were asked to fill in a questionnaire included demographic information and medical history and also a stress questionnaire. Serum leptin level was measured by enzyme-linked immunosorbent assay method. Chi-square, Student t test, Pearson correlation and logistic regression were used for investigating the relationships between variables.

RESULTS

Mean serum leptin levels were 7.41 and 19.33 ng/mL in IBS and control groups, respectively (P<0.001). Participants in IBS group had significantly higher stress levels than controls (P<0.001). Multivariate logistic regression analysis showed that adjusted odds ratios (ORs) for serum leptin level (OR: 0.9; 95% confidence interval: 0.85-0.94) and stress level (OR: 1.15; 95% confidence interval: 1.09-1.23) were nearly the same as crude ones.

CONCLUSIONS

This study indicated the relationship between leptin and IBS for the first time. Our results show that serum leptin level is significantly lower in IBS group than controls and this relationship is independent of other variables such as stress levels, body mass index, etc. This may help in better understanding of the pathogenesis of IBS and consequently lead to the development of more effective treatments.

Failure of the feeding response to fasting in carnitine-deficient juvenile visceral steatosis (JVS) mice: involvement of defective acyl-ghrelin secretion and enhanced corticotropin-releasing factor signaling in the hypothalamus

Carnitine-deficient juvenile visceral steatosis (JVS) mice, suffering from fatty acid metabolism abnormalities, have reduced locomotor activity after fasting. We examined whether JVS mice exhibit specific defect in the feeding response to fasting, a key process of anti-famine homeostatic mechanism. Carnitine-deficient JVS mice showed grossly defective feeding response to 24 h-fasting, with almost no food intake in the first 4 h, in marked contrast to control animals. JVS mice also showed defective acyl-ghrelin response to fasting, less suppressed leptin, and seemingly normal corticotropin-releasing factor (CRF) expression in the hypothalamus despite markedly increased plasma corticosterone. The anorectic response was ameliorated by intraperitoneal administration of carnitine or acyl-ghrelin, with decreased CRF expression. Intracerebroventricular treatment of CRF type 2 receptor antagonist, anti-sauvagine-30, recovered the defective feeding response of 24 h-fasted JVS mice. The defective feeding response to fasting in carnitine-deficient JVS mice is due to the defective acyl-ghrelin and enhanced CRF signaling in the hypothalamus through fatty acid metabolism abnormalities. In this animal model, carnitine normalizes the feeding response through an inhibition of CRF.

Effects of short-term mild calorie restriction diet and renutrition with ruminant milks on leptin levels and other metabolic parameters in mice

OBJECTIVE

The adaptation of an organism to a calorie-restricted diet is characterized by metabolic, endocrine, and immunologic changes. The objective of this study was to determine, in a mouse model, the changes in serum leptin levels in response to short-term mild calorie-restricted and renutrition diets using different ruminant milks.

METHODS

Weaned Swiss albino mice were fed with a mild calorie-restricted diet for 12 d, after which they were renourished with cow, goat, sheep, or buffalo milk for 7 d. Body, thymus, and spleen weights and biochemical, hematologic, and endocrine parameters were evaluated.

RESULTS

The mild calorie restriction did not significantly modify insulin and leptin levels. The renutrition diets increased insulin levels, being significant (P < 0.05) only when buffalo and sheep milks were used. Leptin concentrations increased in the control ad libitum (AD) group during the assayed period. After the administration of cow and goat milks, lower leptin levels were observed compared with the control AD group. All repletion diets significantly increased body, thymus, and spleen weights; however, spleen weight did not reach the values observed in the control AD group. Serum glucose and triacylglycerol levels increased after feeding with the renutrition diets. However, serum cholesterol did not increase after the renutrition period. We observed a significant decrease (P < 0.05) in the leukocyte counts in calorie-restricted mice in comparison with AD mice; after the renutrition period, the leukocyte count did not reach the values for the AD mice.

CONCLUSION

This study suggests that a short-term change in diet with a relatively low body weight loss does not significantly affect leptin concentrations in our mouse model. However, the assayed milks could be effectively used as alternative milk sources for weight gain and for the improvement of other metabolic parameters.

Reproductive endocrinology and clinical aspects of obesity in women

Obesity is a growing worldwide problem and is associated with a wide range of adverse effects on the female reproductive system. The endocrinological changes in obesity that may cause these adverse effects are complex and include changes in circulating adipokines and sex steroids as well as insulin resistance. Considerable evidence suggests an adverse effect of obesity on the risk of miscarriage and other maternal and fetal complications. Obese patients are also more prone to infertility. The most important single method to improve reproductive performance in obese women is weight loss that can be achieved with lifestyle changes and diet. Antiobesity drugs may also be used and, in severe cases, bariatric surgery.

Central nervous system neuropeptide Y signaling modulates VLDL triglyceride secretion

OBJECTIVE

Elevated triglyceride (TG) is the major plasma lipid abnormality in obese and diabetic patients and contributes to cardiovascular morbidity in these disorders. We sought to identify novel mechanisms leading to hypertriglyceridemia. Resistance to negative feedback signals from adipose tissue in key central nervous system (CNS) energy homeostatic circuits contributes to the development of obesity. Because triglycerides both represent the largest energy depot in the body and are elevated in both the plasma and adipose in obesity and diabetes, we hypothesized that the same neural circuits that regulate energy balance also regulate the secretion of TGs into plasma.

RESEARCH DESIGN AND METHODS

In normal fasting rats, the TG secretion rate was estimated by serial blood sampling after intravascular tyloxapol pretreatment. Neuropeptide Y (NPY) signaling in the CNS was modulated by intracerebroventricular injection of NPY, receptor antagonist, and receptor agonist.

RESULTS

A single intracerebroventricular injection of NPY increased TG secretion by 2.5-fold in the absence of food intake, and this was determined to be VLDL by fast performance liquid chromatography (FPLC). This effect was recapitulated by activating NPY signaling in downstream neurons with an NPY-Y5 receptor agonist. An NPY-Y1 receptor antagonist decreased the elevated TGs in the form of VLDL secretion rate by 50% compared with vehicle. Increased TG secretion was due to increased secretion of VLDL particles, rather than secretion of larger particles, because apolipoprotein B100 was elevated in FPLC fractions corresponding to VLDL.

CONCLUSIONS

We find that a key neuropeptide system involved in energy homeostasis in the CNS exerts control over VLDL-TG secretion into the bloodstream.

Association of sleep apnea severity and obesity with insulin resistance, C-reactive protein, and leptin levels in male patients with obstructive sleep apnea

Obesity is the major confounding factor in the relationship between obstructive sleep apnea and increased risk for cardiovascular disease. The aim of the study was to investigate the association of sleep apnea severity with insulin resistance, leptin, and CRP levels in a cohort of male patients. Sixty-seven men referred to our sleep laboratory for evaluation of suspected obstructive sleep apnea syndrome (OSAS) were divided into three groups according to apnea severity: non-OSAS group (n=15), mild to moderate OSAS group (n=26), and severe OSAS (n=26). Insulin resistance was estimated by the homeostasis model assessment method. HOMA values were similar in the three groups: (3.2+/-2.2 vs. 3.3+/-1.8 vs. 3.6+/-1.5, respectively, p=0.71). Leptin levels were higher in the mild to moderate OSAS group (23.1+/-21.8 ng/ml, p<0.05) and in the severe OSAS group (20.2+/-17.5 ng/ml, p<0.05) than in the non-OSAS group (9.4+/-6.4 ng/ml). CRP levels were significantly higher in severe sleep apnea (0.35+/-0.3 vs. 0.19+/-0.1 mg/dl, p<0.05). In multiple regression analyses, waist-to-hip ratio (WHR) was the most significant determinant of HOMA estimation for insulin resistance. WHR and the percentage of total sleep time spent with hypoxemia (%TST with SaO2 <90%) were significant predictors for leptin levels, while body mass index (BMI) and the %TST with SaO2 <90% were the best predicting parameters for CRP levels. Insulin resistance estimated by the HOMA method in male patients with OSAS was not associated with sleep apnea severity independent of obesity. The severity of nocturnal hypoxemia was associated with leptin and CRP levels independent of obesity.

Hyperglycaemic hyperosmolar nonketotic state as a cause of low gonadotrophin levels in postmenopausal diabetic women: a role for severe hypernatraemia

Hypogonadotrophic hypogonadism is associated with uncontrolled diabetes mellitus. Hyperglycaemia is a unique metabolic abnormality of the hyperglycaemic hyperosmolar nonketotic state (HHNKS) and, as glucose availability regulates gonadotrophin release, we investigated whether gonadotrophin release is inhibited in diabetic women with HHNKS, and whether hyperglycaemia, hypernatraemia or both inhibit in vitro gonadotrophin-releasing hormone (GnRH) expression in GT1-7 neurones. Three groups of postmenopausal women were studied: nine diabetics with HHNKS, nine hospitalised ill nondiabetics and 15 healthy women. In addition, the effects of glucose (5.55, 33.3, 66.6 mmol/l) and sodium chloride (150 and 170 mmol/l) on GnRH expression were investigated using GT1-7 neurones. Postmenopausal diabetics with HHNKS showed a decrease in serum levels of luteinising hormone (diabetic HHNKS 2.2 +/- 0.9 IU/l versus ill nondiabetic 21.0 +/- 2.3 IU/l and healthy controls 20.9 +/- 2.8 IU/l, P < 0.01), follicle-stimulating hormone (diabetic HHNKS 8.2 +/- 2.1 IU/l versus ill nondiabetic 50.4 +/- 9.1 IU/l and controls 60.2 +/- 6.9 IU/l, P < 0.01) and free 3,5,3'-triiodothyronine (diabetic HHNKS 1.48 +/- 0.57 pmol/l versus ill nondiabetic 4.28 +/- 0.26 pmol/l and controls 3.88 +/- 0.11 pmol/l, P < 0.01). The plasma cortisol level was higher in both diabetic (985 +/- 130 nmol/l) and ill nondiabetic (726 +/- 52 nmol/l) women than in healthy women (512 +/- 47 nmol/l), but no differences were observed in plasma oestradiol, thyroid-stimulating hormone or free thyroxine. In vitro GT1-7 neurones expressed three-fold less GnRH at 170 mmol/l than at 150 mmol/l NaCl, whereas changing glucose concentrations in the culture medium did not affect GnRH expression. In conclusion, postmenopausal diabetic women with HHNKS show decreased serum gonadotrophin levels, and severe hypernatraemia may participate in the hypogonadotropism observed in HHNKS.

Association of cognitive restraint with ghrelin, leptin, and insulin levels in subjects who are not weight-reduced

Despite widespread efforts at weight loss, the prevalence of obesity continues to rise. Restrained eating is a pattern of attempted weight control characterized by cognitive restriction of food intake that has paradoxically been linked with overeating and/or weight gain. It is not known whether restrained eating is associated with abnormalities in appetite-regulating hormones, independent of its effects on body weight. To address this question, we assessed cognitive restraint using the Three-Factor Eating Questionnaire and obtained fasting measurements of ghrelin, leptin and insulin from 24 healthy, non-obese (body mass index (BMI) 19.7 to 29.6 kg/m(2)) adult subjects who were at a stable, lifetime maximum weight. We chose to study subjects at stable maximum weight to avoid the secondary effects of weight reduction on body-weight regulating hormones. Subjects were classified by cognitive restraint scale score into Low, Indeterminate, and High Restraint groups. Higher ghrelin levels were significantly associated with restraint in an unadjusted model (P=0.004) and after adjustment for BMI (P=0.007). No relationships were found between restraint scores and either leptin (P=0.75) or insulin (P=0.36). These findings show an orexigenic hormonal profile in restrained eaters, independent of changes in body weight.

Activation of AMP-activated protein kinase stimulates proopiomelanocortin gene transcription in AtT20 corticotroph cells

Starvation is known to activate the hypothalamo-pituitary-adrenal (HPA) axis, a representative antistress system in the living organism. In this study, we investigated in vitro whether activation of the AMP-activated protein kinase (AMPK), which is known to occur in intracellular energy depletion, influences the expression of POMC gene that encodes adrenocorticotropin. We first confirmed that each subunit of AMPK was expressed in the AtT20 corticotroph cell line. We then found that AICAR, a cell-permeable AMP analog and an activator of AMPK, potently stimulated the 5'-promoter activity of POMC gene in a dose-dependent manner. The effects were promoter specific because AICAR enhanced the AP1-mediated POMC promoter activities but did not influence other transcription factor-induced transcription. The effect of AICAR on POMC gene transcription was completely eliminated by specific AMPK inhibitor compound C or by dominant negative AMPK, whereas overexpression of constitutively active AMPK mimicked the effect of AICAR. Finally, experiments using specific kinase inhibitors suggested that the PI 3-kinase-mediated signaling pathway is at least partly involved in the effect. Our results suggest that intracellular energy depletion with the resultant activation of AMPK directly stimulates the HPA axis at the pituitary level by increasing the expression of POMC gene.

Monoclonal antibody antagonists of hypothalamic FGFR1 cause potent but reversible hypophagia and weight loss in rodents and monkeys

We generated three fully human monoclonal antibody antagonists against fibroblast growth factor receptor-1 (FGFR1) that potently block FGF signaling. We found that antibodies targeting the c-splice form of the receptor (FGFR1c) were anorexigenic when administered intraperitoneally three times weekly to mice, resulting in rapid, dose-dependent weight loss that plateaued (for doses>4 mg/kg) at 35-40% in 2 wk. Animals appeared healthy during treatment and regained their normal body weights and growth trajectories upon clearance of the antibodies from the bloodstream. Measurements of food consumption and energy expenditure indicated that the rapid weight loss was induced primarily by decreased energy intake and not by increased energy expenditure or cachexia and was accompanied by a greater reduction in fat than lean body mass. Hypophagia was not caused through malaise or illness, as indicated by absence of conditioned taste aversion, pica behavior, and decreased need-induced salt intake in rats. In support of a hypothalamic site of action, we found that, after intraperitoneal injections, anti-FGFR1c (IMC-A1), but not a control antibody, accumulated in the median eminence and adjacent mediobasal hypothalamus and that FGFR1c is enriched in the hypothalamus of mice. Furthermore, a single intracerebroventricular administration of 3 microg of IMC-A1 via the 3rd ventricle to mice caused an approximately 36% reduction in food intake and an approximately 6% weight loss within the ensuing 24 h. Our data suggest that FGF signaling through FGFR1c may play a physiological role in hypothalamic feeding circuit and that blocking it leads to hypophagia and weight loss.

Patogenia de la lipodistrofia y de las alteraciones metabólicas asociadas a la infección por el VIH

Lipodystrophy, and the metabolic alterations (dislipemia, insulin-resistance) associated with human immunodeficiency virus (HIV) infection, is a multifactorial syndrome due to the interaction of host related factors (cellular immune status, diet, gene mutations), viral factors (cytokine synthesis, polyunsaturated fatty acid or PUFA depletion), and pharmacological effects (mitochondrial DNA-polymerase inhibition, lipolysis inhibition, adiponectin synthesis reduction). HIV probably modifies the adipocyte differentiation and the lipid metabolism. This retroviral effect is mediated by proinflammatory cytokines (tumor necrosis factor) and the participation of other factors (drugs, diet), all in the context of a particular host genetic setting. The adipocyte (and several cellular receptors, fatty acids, membrane proteins, and cytokines) plays a central role in the pathogenesis of HIV-associated lipodystrophy.