Peripheral signals conveying metabolic information to the brain: short-term and long-term regulation of food intake and energy homeostasis

Emerging role of glial cells in the control of body weight

Glia are the most abundant cell type in the brain and are indispensible for the normal execution of neuronal actions. They protect neurons from noxious insults and modulate synaptic transmission through affectation of synaptic inputs, release of glial transmitters and uptake of neurotransmitters from the synaptic cleft. They also transport nutrients and other circulating factors into the brain thus controlling the energy sources and signals reaching neurons. Moreover, glia express receptors for metabolic hormones, such as leptin and insulin, and can be activated in response to increased weight gain and dietary challenges. However, chronic glial activation can be detrimental to neurons, with hypothalamic astrocyte activation or gliosis suggested to be involved in the perpetuation of obesity and the onset of secondary complications. It is now accepted that glia may be a very important participant in metabolic control and a possible therapeutical target. Here we briefly review this rapidly advancing field.

Short-term effects of ratio of energy nutrients on appetite-related hormones in female college students

Understanding the relationship between energy nutrients compositions in a diet and appetite-controlling substances is essential for providing sound advice to anyone attempting to control body weight. Appetite is known to be affected by various hormones, ghrelin and peptide tyrosine-tyrosine (PYY), which are related to the compositions of a diet. The purpose of this study was to investigate the effects of compositions of energy nutrients in the diet on the levels of postprandial appetite-related hormones and satiety in healthy adult women. Ten subjects (BMI: 18.5-22.9 kg/m²) were recruited and assigned to three iso-coloric breakfast meals with different compositions of energy nutrients, regular meal (RM, CHO: 60%, Pro: 20%, Fat: 20%), high protein meal (HPM, CHO: 30%, Pro: 50%, Fat: 20%), and high fat meal (HFM, CHO: 30%, Pro: 20%, Fat: 50%). Blood levels of ghrelin, PYY, insulin and leptin and satiety were assessed at baseline, 30, 60, 90, 120, and 180 min following the consumption of each meal. There was no significant difference in the fasting blood hormones among the subjects taking each meals at baseline. Blood levels of ghrelin and insulin changed significantly following the consumption of each meal (p<0.05) over time, however no significant difference was shown between experimental meals until 180 min. Blood levels of PYY and leptin were not changed following the ingestion of each meals. In conclusion, the composition of energy nutrients in a diet had no effect on the postprandial plasma levels of ghrelin, PYY, insulin and leptin as well as satiety in healthy adult women.

Effect of feed restriction on metabolites in cerebrospinal fluid and plasma of dairy cows

Endocrines and metabolites in the circulation act as long-term hunger or satiety signals in the brain during negative energy balance and play an important role in the control of feed intake. These signals also occur in the cerebrospinal fluid (CSF), which surrounds the hypothalamus and brainstem: 2 major centers of feed intake regulation. Thus CSF functions as a transport medium for fuel signals between blood and brain. The CSF metabolite concentrations are mainly under control of the blood-brain barriers, which provide specific carrier molecules facilitating the entry of substances required by the brain and protect the brain from factors that could impair neuronal function. The transport of small molecules such as amino acids (AA) across the blood-brain barriers may be limited by competing AA that share a common transporter for the uptake into brain. Consequently, CSF metabolite concentrations differ from those in blood. Thus it appears likely that central (CSF) rather than peripheral (blood) metabolites act as pivotal signals for the control of feed intake. However, the contribution of putative orexigenic and anorexigenic signals in CSF of cows has not been studied so far. Therefore, the aim of this study was to elucidate associations existing between both plasma and CSF metabolites, each in response to feed restriction-induced negative energy balance. Seven German Holstein dairy cows, between 87 and 96 DIM of the second lactation (milk yield, 27.9 L/d) were fed ad libitum (AL) for 4 d and CSF from the spinal cord and blood from the jugular vein was withdrawn before morning feeding at the fifth day. Subsequently, animals were feed restricted (R) to 50% of the previous AL intake for 4 d and CSF and plasma were collected at the ninth day. Body weight, feed intake, water intake, and milk production were determined. Thirty-one AA, β-hydroxybutyric acid, cholesterol, glucose, lactate, nonesterified fatty acids, urea, and osmolality were measured in both CSF and plasma, whereas free fatty acids and volatile fatty acids were determined in plasma only. Although plasma arginine (132%), leucine (134%), lysine (117%), nonesterified fatty acids (224%), and cholesterol (112%) increased, tryptophan and carnosine decreased (-33% and -20%, respectively) in R animals as compared with AL animals. In CSF, concentrations of these metabolites were not affected after R feeding, suggesting that these identified plasma metabolites have only little potential to contribute to central feed intake regulatory signaling in cows. By contrast, in CSF, serine, threonine, and tyrosine decreased (-20, -24, and -31%, respectively) after R feeding. Therefore, these 3 AA are potential centrally acting anorexigenic signals in cows.

Chronic restricted access to food leading to undernutrition affects rat neuroendocrine status and olfactory-driven behaviors

Previous studies have demonstrated that olfactory-driven behaviors in rats are influenced by short-term caloric restriction, partly through the modulation of olfactory sensitivity by appetite-modulating hormones or peptides such as insulin and leptin. Here, we addressed the issue of a long-term modulation of their neuroendocrine status by evaluating the effect of chronic food restriction in rats following a limitation of the duration of daily food intake to 2 h (SF) instead of 8 h (LF) on the expression of insulin and leptin system in the olfactory mucosa and bulb and on olfactory behaviors. This restriction resulted in a one-third reduction in the daily food intake and a 25% reduction in the body weight of SF rats when compared to controls, and was accompanied by lower levels of triglycerides, glucose, insulin and leptin in SF rats. Under these conditions, we observed a modulation of olfactory-mediated behaviors regarding food odors. In addition, restriction had a differential effect on the expression of insulin receptors, but not that of leptin receptors, in the olfactory mucosa, whereas no transcriptional change was observed at the upper level of the olfactory bulb. Overall, these data demonstrated that long-term changes in nutritional status modulate olfactory-mediated behaviors. Modulation of insulin system expression in the olfactory mucosa of food restricted rats suggests that this hormone could be part of this process.

Leptin, a tool of parasites?

One common physiological phenomenon that is involved both in infectious and in malignant processes is the reduction in appetite: disease anorexia. An increase in plasma levels of leptin with inflammation is thought to be involved in this process. However, from an evolutionary perspective, in certain cases, it would be more adaptive for an internal parasite to stimulate the appetite of the host instead of causing its suppression. We tested whether a parasitic infection with the larvae of the helminth parasite Taenia taeniaformis affects the levels of appetite-regulating proteins, such as leptin, ghrelin and neuropeptide-Y (NPY) in wild yellow-necked mouse (Apodemus flavicollis). We found that infected mice had lower plasma levels of leptin and increased levels of NPY than the uninfected subjects. Ghrelin levels were not associated with the occurrence of the parasites; however, these levels strongly correlated with the levels of NPY. This study suggests a possible manipulation by parasitic larvae of appetite regulation in infected subjects.

Measurement of ad libitum food intake, physical activity, and sedentary time in response to overfeeding

Given the wide availability of highly palatable foods, overeating is common. Energy intake and metabolic responses to overfeeding may provide insights into weight gain prevention. We hypothesized a down-regulation in subsequent food intake and sedentary time, and up-regulation in non-exercise activity and core temperature in response to overfeeding in order to maintain body weight constant. In a monitored inpatient clinical research unit using a cross over study design, we investigated ad libitum energy intake (EI, using automated vending machines), core body temperature, and physical activity (using accelerometry) following a short term (3-day) weight maintaining (WM) vs overfeeding (OF) diet in healthy volunteers (n = 21, BMI, mean ± SD, 33.2±8.6 kg/m², 73.6% male). During the ad libitum periods following the WM vs. OF diets, there was no significant difference in mean 3-d EI (4061±1084 vs. 3926±1284 kcal/day, p = 0.41), and there were also no differences either in core body temperature (37.0±0.2°C vs. 37.1±0.2°C, p = 0.75) or sedentary time (70.9±12.9 vs. 72.0±7.4%, p = 0.88). However, during OF (but not WM), sedentary time was positively associated with weight gain (r = 0.49, p = 0.05, adjusted for age, sex, and initial weight). In conclusion, short term overfeeding did not result in a decrease in subsequent ad libitum food intake or overall change in sedentary time although in secondary analysis sedentary time was associated with weight gain during OF. Beyond possible changes in sedentary time, there is minimal attempt to restore energy balance during or following short term overfeeding.

Morbidly obese are ghrelin and leptin hyporesponders with lesser intragastric balloon treatment efficiency : ghrelin and leptin changes in relation to obesity treatment

BACKGROUND

Ghrelin and leptin recently emerged as the most influential neuroendocrine factors in the pathophysiology of obesity. The said peptides act in reciprocity and are responsible for regulation of appetite and energy metabolism. Intragastric balloons acquired worldwide popularity for obesity treatment. However, the roles of ghrelin and leptin in intragastric balloon treatment were still not systematically studied.

METHODS

A prospective single-center study included 43 Caucasians treated with BioEnterics intragastric balloon, with age range of 18-60, and divided to non-morbid (body mass index cutoff 40 kg/m(2)) or morbid type of obesity, with 12 months follow-up. Serum hormonal samples were taken from fasting patients and kept frozen until analyses.

RESULTS

Significant differences were observed in anthropometrics and there were no differences between genders or comorbidities. The baseline weight for non-morbid vs. morbid was 104 kg (90-135) vs. 128.5 kg (104-197). Weight loss was statistically different between the studied groups during the study course with a median control weight at 6 months of 92 kg (72-121) vs. 107 kg (84-163), p < 0.001. Treatment was successful for 18 (94.7%) vs. 16 (66.7%) patients, p = 0.026. Ghrelin varied from 333.3 to 3,416.8 pg/ml and leptin from 1.7 to 61.2 ng/ml, with a statistically significant time-dependent relationship. A significant difference (p = 0.04) with emphasized ghrelin peak was found in the 3rd month of treatment for non-morbidly obese subjects.

CONCLUSIONS

The importance of ghrelin and leptin in treatment-induced changes was reaffirmed. Ghrelin hyper-response in non-morbidly obese subjects characterized greater short-term treatment efficiency and landmarked an inclination to weight regain. The results suggest a potential pattern of individualization between obese patients according to body mass index towards intragastric balloon or bariatric surgery. Further studies are needed in order to get better insights in the pathophysiologic mechanisms of obesity.

Possible involvement of melanocortin-4-receptor and AMP-activated protein kinase in the interaction of glucagon-like peptide-1 and leptin on feeding in rats

Glucagon-like peptide-1 (GLP-1) and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important to elucidate a mechanism to maintain energy balance. In the present study, coadministration of subthreshold GLP-1 and leptin dramatically reduced feeding in rats. Although coadministration of GLP-1 with leptin did not enhance leptin signal transduction in the hypothalamus, it significantly decreased phosphorylation of AMP-activated protein kinase (AMPK). In addition, coadministration of GLP-1 with leptin significantly increased proopiomelanocortin (POMC) mRNA levels. Considering that α-melanocortin stimulating hormone (α-MSH) is derived from POMC and functions through the melanocortin-4-receptor (MC4-R) as a key molecule involved in feeding reduction, the interaction of GLP-1 and leptin on feeding reduction may be mediated through the α-MSH/MC4-R system. As expected, the interaction of GLP-1 and leptin was abolished by intracerebroventricular preadministration of the MC4-R antagonists agouti-related peptide and SHU9119. Taken together, GLP-1 and leptin cooperatively reduce feeding at least in part via inhibition of AMPK following binding of α-MSH to MC4-R.

Pathophysiological role of hormones and cytokines in cancer cachexia

We investigated the role of fasting hormones and pro-inflammatory cytokines in cancer patients. Hormones (ghrelin, adiponectin, and leptin) and cytokines (TNF-α, IFN-γ, and IL-6) were measured by ELISA or RIA in lung cancer and colorectal cancer patients before the administration of cancer therapy, and measurements were repeated every 2 months for 6 months. From June 2006 to August 2008, 42 patients (19 with colorectal cancer and 23 with lung cancer) were enrolled. In total, 21 patients were included in the cachexia group and the others served as a comparison group. No significant difference in the initial adiponectin, ghrelin, TNF-α, IFN-γ, or IL-6 level was observed between groups, although leptin was significantly lower in cachectic patients than in the comparison group (15.3 ± 19.5 vs 80.9 ± 99.0 pg/mL, P = 0.007). During the follow-up, the patients who showed a > 5% weight gain had higher ghrelin levels after 6 months. Patients exhibiting elevated IL-6 levels typically showed a weight loss > 5% after 6 months. A blunted adiponectin or ghrelin response to weight loss may contribute to cancer cachexia and IL-6 may be responsible for inducing and maintaining cancer cachexia.

Site-specific effects of intracranial estradiol administration on recurrent insulin-induced hypoglycemia in the ovariectomized female rat

Clinical and experimental studies reveal gender differences in susceptibility to dampening effects of precedent hypoglycemia on recurrent insulin-induced hypoglycemia (RIIH). Recent studies implicate the ovarian steroid, estradiol, in the regulation of RIIH, since systemic replacement of this hormone at basal estrous cycle levels maintains glucose profiles during serial insulin dosing and prevents RIIH-associated reductions in neuronal activation in key metabolic structures in the ovariectomized female rat brain. The present study investigated the hypothesis that these effects are achieved, in part, by estrogenic action within the central nervous system, including glucoregulatory structures characterized by high estrogen receptor (ER) expression. Initial experiments evaluated the impact of global intracranial administration of estradiol on RIIH. Ovariectomized rats were treated by continuous infusion of graded doses of 17β-estradiol-3-benzoate (EB) or vehicle into the lateral ventricle (LV), and injected subcutaneously with 1 or 4 doses of the intermediate-release insulin, Humulin N (HN), 1 dose per day. Animals infused with 5 or 10 µg EB/day exhibited uniform glycemic responses to 1 versus 4 doses of insulin, whereas rescue from hypoglycemia was delayed during repetitive HN injection of rats infused with either vehicle or 1 µg EB/day. Recovery from both single and multiple bouts of hypoglycemia was more rapid in rats infused with the higher EB doses, compared to other groups. Mapping of ERα immunoreactivity in animals treated by LV infusion of EB revealed variable nuclear staining in ER-expressing metabolic loci typified by estrogen-dependent sustenance of neuronal reactivity to hypoglycemia, with highest levels of ERα immunoreactivity observed in the arcuate (ARH) and ventromedial (VMH) hypothalamic nuclei, and moderate labeling of the caudal hindbrain dorsal vagal complex. EB delivery to the caudal hindbrain via the caudal fourth ventricle resulted in dose-dependent effects on RIIH, since glycemic profiles were either unchanged or diminished relative to acute NH-induced hypoglycemia, in high versus low EB-treated animals, respectively. Bilateral administration of 1.0 µg EB into the ARH or VMH elicited disparate effects on acute and chronic HN-induced hypoglycemia. Intra-VMH EB delayed recovery from both acute and chronic hypoglycemia, compared to non-estradiol-treated controls. In contrast, neither that dose nor a 10-fold lower dosage of EB delivered to the ARH modified acute HN-induced hypoglycemia, but RIIH was either attenuated or enhanced, respectively, in animals treated by intra-ARH delivery of 1.0 versus 0.1 µg EB, respectively. These results suggest that whole brain exposure to elevated estradiol may promote outflow that truncates hypoglycemia and maintains glucose profiles during RIIH, whereas actions of relatively low hormone levels on the central nervous system may result in adaptive adjustments that result in lower blood glucose levels during recurring versus acute hypoglycemia. The data also imply that, at a given concentration, estrogens may exert site-specific effects on acute and chronic HN-induced hypoglycemia. Further research is needed to identify the cellular substrates and physiological mechanisms that mediate caudal hindbrain-, ARH-, and VMH-specific actions of estradiol on acute and chronic hypoglycemia.

Alcohol intake and its effect on some appetite-regulating hormones in man: influence of gastroprotection with sucralfate

BACKGROUND

Alcohol stimulates appetite. Ghrelin, obestatin, glucagon-like peptide 1 and leptin are putative mediators.

OBJECTIVE

We studied whether alcohol ingestion affects serum levels of these peripheral hormones, and if gastroprotective sucralfate prevents such an effect.

MATERIALS AND METHODS

Ten participants were investigated on four occasions. On one alcohol was ingested; on another alcohol was given after pretreatment with sucralfate; on a third water was ingested; and on a fourth sucralfate was ingested followed by water. Serum hormones and ethanol concentrations were determined.

RESULTS

The ghrelin and leptin levels fell after ingestion of alcohol, whereas the obestatin and GLP-1 levels remained unchanged. Sucralfate did not affect any of the basal four hormone levels, nor the ghrelin or leptin responses to alcohol.

CONCLUSIONS

An appetite-stimulating effect of alcohol is hardly mediated by any of the hormones studied in this investigation, as the GLP-1 and obestatin levels were unaffected by alcohol, the ghelin level decreased, and leptin - although declining after alcohol - has not previously been found to have short-term inhibitory effect on hunger.

Psychobehavioural factors are more strongly associated with successful weight management than predetermined satiety effect or other characteristics of diet

This study aimed to investigate factors associated with weight management, especially whether satiety value of food as a part of a weight-maintenance diet would affect self-regulation of food intake and weight management. Altogether 82 obese subjects completed the study consisting of weight-loss and weight-maintenance (WM) periods. During the WM, subjects were randomized into higher- and lower-satiety food groups. No differences were observed in the changes in body weight, energy intake, or eating behaviour between the groups, even despite the different macronutrient compositions of the diets. However, when regarding all study subjects, success in WM was most strongly associated with a greater increase in the flexible control of eating and experience of greater easiness of WM and control of food intake and a greater decrease in uncontrollable eating and psychological distress. Psychobehavioural factors seem to be more strongly associated with successful weight management than the predetermined satiety effect or other characteristics of the diet.

Successful development of satiety enhancing food products: towards a multidisciplinary agenda of research challenges

In the context of increasing prevalence of overweight and obesity in societies worldwide, enhancing the satiating capacity of foods may help people control their energy intake and weight. This requires an integrated approach between various food-related disciplines. By structuring this approach around the new product development process, this paper aims to present the contours of such an integrative approach by going through the current state of the art around satiety enhancing foods. It portrays actual food choice as the end result of a complex interaction between internal satiety signals, other food benefits, and environmental cues. Three interrelated routes to satiating enhancement are to change the food composition to develop stronger physiological satiation and satiety signals, anticipate and build on smart external stimuli at the moment of purchase and consumption, and improve palatability and acceptance of satiety enhanced foods. Key research challenges in achieving these routes in the field of nutrition, food technology, consumer, marketing, and communication are outlined.

Gastric mammalian target of rapamycin signaling, hormone production and energy metabolism

The obesity epidemic imposes a significant health burden on human beings. Current understanding of the mechanisms underlying the development of obesity is incomplete and contemporary treatment is often ineffective. Gastrointestinal hormones are important regulators of food intake and energy metabolism. Previous studies indicate that the mammalian target of rapamycin signaling pathway in the gastric mucosa is crucially involved in fuel sensing in the gastrointestinal tract and plays a critical role in the coordination of nutrient availability and ingestive behavior via the production of gastric hormones. As an important component of the brain-gut axis regulating food intake and energy homeostasis, energy sensing in the gastrointestinal tract may provide a novel insight into our understanding of the precise coordination between the organism and cellular energy state.

Variations of plasma leptin in show horses during a work season

Leptin is an adipocytokine mainly expressed by adipose tissue. Secretion of leptin in healthy animals is closely related to fat mass and metabolic activity. The aim of this study was to investigate plasma leptin variations, in relation to nutritional and exercise parameters in adult show horses during a work season. EDTA-blood samples were taken at rest from 37 Iberian horses. Body weight, body condition score and fat percentage determined by ultrasonic measurement of rump fat thickness were measured. Plasma leptin was determined with a multi-species RIA kit. Linear mixed effects model was used to assess relationship between plasma leptin and other biological parameters. Plasma leptin concentration was <12.6 ng/ml (mean = 2.8 ± 1.6 ng/ml) and was significantly higher during training periods (p < 0.0001) (4.5 ± 1.7 ng/ml) than in show periods (2.0 ± 1.1 ng/ml), despite a significant increase (p < 0.0001) in energy intake. The body weight remained almost constant. The plasma leptin concentrations were significantly affected by exercise (p < 0.0001), body weight (p = 0.04) and BCS (p < 0.0001), but were not affected by percentage of fat. In conclusion, the marked decrease in leptin values observed during a period of intense (i.e. excessive) exercise could result from an adaptation to cumulative alterations in energy balance, to exercise per se or to a combination of both.

A palatable hyperlipidic diet causes obesity and affects brain glucose metabolism in rats

Background

We have previously shown that either the continuous intake of a palatable hyperlipidic diet (H) or the alternation of chow (C) and an H diet (CH regimen) induced obesity in rats. Here, we investigated whether the time of the start and duration of these feeding regimens are relevant and whether they affect brain glucose metabolism.

Methods

Male Wistar rats received C, H, or CH diets during various periods of their life spans: days 30-60, days 30-90, or days 60-90. Experiments were performed the 60^th or the 90^th day of life. Rats were killed by decapitation. The glucose, insulin, leptin plasma concentration, and lipid content of the carcasses were determined. The brain was sliced and incubated with or without insulin for the analysis of glucose uptake, oxidation, and the conversion of [1-¹⁴C]-glucose to lipids.

Results

The relative carcass lipid content increased in all of the H and CH groups, and the H30-60 and H30-90 groups had the highest levels. Groups H30-60, H30-90, CH30-60, and CH30-90 exhibited a higher serum glucose level. Serum leptin increased in all H groups and in the CH60-90 and CH30-90 groups. Serum insulin was elevated in the H30-60, H60-90, CH60-90, CH30-90 groups. Basal brain glucose consumption and hypothalamic insulin receptor density were lower only in the CH30-60 group. The rate of brain lipogenesis was increased in the H30-90 and CH30-90 groups.

Conclusion

These findings indicate that both H and CH diet regimens increased body adiposity independent treatment and the age at which treatment was started, whereas these diets caused hyperglycemia and affected brain metabolism when started at an early age.

Fetal hypothalamic neuroprogenitor cell culture: preferential differentiation paths induced by leptin and insulin

In response to temporally orchestrated growth factor stimulation, developing neural stem/progenitor cells undergo extensive self-renewal and then generate neurons and astrocytes. Fetal neonatal leptin and insulin deficiency results in reduced hypothalamic axonal pathways regulating appetite, which may predispose to offspring hyperphagia and obesity. Neural development of the arcuate nucleus, a key target of adiposity signals, leptin and insulin, is immature at birth. Hence, to explore proximate effects of leptin/insulin on hypothalamic development, we determined trophic and differentiation effects on neural stem/progenitor cells using a model of fetal hypothalamic neurospheres (NS). NS cultures were produced from embryonic d 20 fetal rats and passage 1 and passage 2 cells examined for proliferation and differentiation into neurons (neuronal nuclei, class IIIβ-tubulin, and doublecortin) and astrocytes (glial fibrillary acidic protein). Leptin-induced NS proliferation was significantly greater than that induced by insulin, although both effects were blocked by Notch, extracellular signal-regulated kinase, or signal transducer and activator of transcription 3 inhibition. Leptin preferentially induced neuronal, whereas insulin promoted astrocyte differentiation. Extracellular signal-regulated kinase inhibition suppressed both leptin and insulin-mediated differentiation, whereas signal transducer and activator of transcription inhibition only affected leptin-mediated responses. These findings demonstrate preferential and disparate differentiation paths induced by leptin and insulin. Altered fetal exposure to leptin or insulin, resulting from fetal growth restriction, macrosomia, or maternal diabetes, may potentially have marked effects on fetal brain development.

Cardiovascular risk in obesity: different activation of inflammation and immune system between obese and morbidly obese subjects

BACKGROUND

Both inflammation and immunity are involved in the development and progression of atherosclerosis. Obesity is considered a major modifiable cardiovascular risk factor, however, the correlation between increasing degrees of obesity and cardiovascular risk is not clear yet. Aim of our study was to investigate how different degrees of obesity are associated with inflammation and immune system responses.

METHODS

One-hundred healthy individuals were divided into 3 groups according to body mass index (BMI): 22 overweight (OW), 26 obese (O) and 52 morbidly obese (MO). High-sensitivity C-Reactive Protein (hs-CRP, immunonephelometry), leptin (radio-immunoassay) and CD4+CD28nullT-lymphocytes (flow-cytometry), a particular subset of T-lymphocytes with pro-atherogenic and plaque-destabilizing properties, were assessed.

RESULTS

hs-CRP levels were significantly higher in O vs OW (p=0.036), in MO vs OW (p<0.001) and in MO vs O (p=0.012). Similarly, leptin levels were higher in O vs OW (p=0.02), in MO vs OW (p<0.001) and in MO vs O (p<0.001). CD4+CD28nullT-lymphocytes were higher in O vs OW (p<0.001), in O vs MO (p=0.03) and in MO vs OW (p=0.01). hs-CRP and leptin levels significantly correlated each other (r=0.39; p<0.001) and with waist circumference (r=0.52; p<0.001; r=0.64; p<0.001) and BMI (r=0.60; p<0.001; r=0.74; p<0.001).

CONCLUSIONS

Our study demonstrates that, notwithstanding higher levels of inflammation, MO are characterized by less detrimental immune activation, as shown by the reduced CD4+CD28nullT-cells expansion as compared to OW and O, which might translate in less immune vascular injury. These findings suggest that MO might represent a particular population, in which different pathophysiological mechanisms take part if compared with "classic" obesity.

The relationship among acute-phase responce proteins, cytokines, and hormones in various gastrointestinal cancer types patients with cachectic

BACKGROUND

Acute-phase response proteins (APRPs), cytokines, and hormones have been claimed to be an independent, important factor of cancers. We suggest that in gastrointestinal system cancers, changes in APRP, cytokines, and hormones are associated.

METHODS

C-reactive protein (CRP), albumin, interleukin 1α (IL-1α), IL-1β, IL-6, IL-8, IL-10, tumor necrosis factor α (TNF-α), midkine, vascular endothelial growth factor-A(VEGF-A), VEGF-C, VEGF receptor 1 (VEGFR1), leptin, adiponectin, and ghrelin serum levels are studied in 148 gastrointestinal system cancer types and 40 healthy controls.

RESULTS

We found statistically significant differences and correlations between groups. We found significantly higher serum CRP, IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, VEGF-A, VEGF-C, VEGFR1, and leptin concentrations in patients with esophageal, gastric, pancreas, colon, and rectum cancers than controls (p < 0.001, p < 0.0001). But, we found lower levels of the serum albumin, midkine, adiponectin, and ghrelin in patients with esophageal, gastric, pancreas, colon, and rectum cancers compared to control subjects (p < 0.05, p < 0.001).

CONCLUSIONS

Cachexia in gastrointestinal system cancer types is associated with changes in APRP, cytokines, and hormone concentrations. This may be reflected between the outcomes in malignancies and the biomarkers.

Compensation for obesity-induced insulin resistance in dogs: assessment of the effects of leptin, adiponectin, and glucagon-like peptide-1 using path analysis

The hormonal mediators of obesity-induced insulin resistance and compensatory hyperinsulinemia in dogs have not been identified. Plasma samples were obtained after a 24-h fast from 104 client-owned lean, overweight, and obese dogs. Plasma glucose and insulin concentrations were used to calculate insulin sensitivity and β-cell function with the use of the homeostasis model assessment (HOMA(insulin sensitivity) and HOMA(β-cell function), respectively). Path analysis with multivariable linear regression was used to identify whether fasting plasma leptin, adiponectin, or glucagon-like peptide-1 concentrations were associated with adiposity, insulin sensitivity, and basal insulin secretion. None of the dogs were hyperglycemic. In the final path model, adiposity was positively associated with leptin (P < 0.01) and glucagon-like peptide-1 (P = 0.04) concentrations. No significant total effect of adiposity on adiponectin in dogs (P = 0.24) was observed. If there is a direct effect of leptin on adiponectin, then our results indicate that this is a positive relationship, which at least partly counters a negative direct relationship between adiposity and adiponectin. Fasting plasma leptin concentration was directly negatively associated with fasting insulin sensitivity (P = 0.01) and positively associated with β-cell function (P < 0.01), but no direct association was observed between adiponectin concentration and either insulin sensitivity or β-cell function (P = 0.42 and 0.11, respectively). We conclude that dogs compensate effectively for obesity-induced insulin resistance. Fasting plasma leptin concentrations appear to be associated with obesity-associated changes in insulin sensitivity and compensatory hyperinsulinemia in naturally occurring obese dogs. Adiponectin does not appear to be involved in the pathophysiology of obesity-associated changes in insulin sensitivity.

Acute injection of ASP in the third ventricle inhibits food intake and locomotor activity in rats

Acylation-stimulating protein (ASP; also known as C3adesArg) stimulates triglyceride synthesis and glucose transport via interaction with its receptor C5L2, which is expressed peripherally (adipose tissue, muscle) and centrally. Previous studies have shown that ASP-deficient mice (C3KO) and C5L2-deficient mice (C5L2KO) are hyperphagic (59 to 229% increase, P < 0.0001), which is counterbalanced by increased energy expenditure measured as oxygen consumption (Vo(2)) and a lower RQ. The aim of the present study was to evaluate ASP's effect on food intake, energy expenditure, and neuropeptide expression. Male rats were surgically implanted with intracerebroventricular (icv) cannulas directed toward the third ventricle. After a 5-h fast, rats were injected, and food intake was assessed at 0.5, 1, 2, 4, 16, 24, and 48 h, with a 5- to 7-day washout period between each injection. Acute icv injections of ASP (0.3-1,065 pmol) had a time-dependent effect on decreasing food intake by 20 to 57% (P < 0.05). Decreases were detected by 30 min (maximum 57%, P < 0.01) and at the highest dose effects extended to 48 h (19%, P < 0.05, 24- to 48-h period). Daily body weight gain was decreased by 131% over the first 24 h and 29% over the second 24 h (P < 0.05). A conditioned taste aversion test indicated that there was no malaise. Furthermore, acute ASP injection affected energy substrate usage, demonstrated by decreased Vo(2) and RQ (P < 0.05; implicating greater fatty acid usage), with a 49% decrease in total activity over 24 h (P < 0.05). ASP administration also increased anorexic neuropeptide POMC expression (44%) in the arcuate nucleus, with no change in NPY. Altogether ASP may have central in addition to peripheral effects.

Effects of improving glycemic control with insulin on leptin, adiponectin, ghrelin and neuropeptidey levels in patients with type 2 diabetes mellitus: a pilot study

OBJECTIVE

Insulin therapy is associated with weight gain in patients with type 2 diabetes mellitus (T2DM). Several peptides are implicated in appetite control. We evaluated the effects of insulin-induced improved glycaemic control on leptin, adiponectin, ghrelin, neuropeptide Y (NPY) levels and patient characteristics.

METHOD

Consecutive T2DM patients (n = 90) were divided into 2 groups: Group A: 45 insulin-naïve uncontrolled (glycosylated haemoglobin A(1c); HbA(1c )>7%) patients on oral hypoglycaemic agents (OHAs) who converted to insulin monotherapy. Group B: 45 well-controlled (HbA(1c )<7%) patients on OHAs. Both groups were monitored at baseline, 3 and 6 months. Males and females were analyzed separately because some hormone levels differ between genders.

RESULTS

In both genders, insulin therapy (Group A) was associated with significant (p = 0.003 to <0.001) increases in weight, body mass index and leptin levels and significant decreases in glucose, HbA(1c) and NPY levels. In male insulin-treated patients a significant increase in adiponectin levels (p = 0.008) was observed. There were significant correlations (p = 0.016 to <0.001) between leptin levels, waist circumference and body fat in all patient groups, except group B males.

CONCLUSION

Changes in leptin, adiponectin and NPY levels may occur after insulin-induced improved glycaemic control. These changes may be influenced by gender, weight, body fat and HbA(1c).

Association of serum levels of leptin, ghrelin, and adiponectin in schizophrenic patients and healthy controls

BACKGROUND

Leptin, ghrelin, and adiponectin play important roles in the regulation of body weight, food intake, and energy homeostasis, and have been suggested to be important biomarkers of metabolic syndrome. In this study, we tried to simultaneously investigate the serum levels of leptin, ghrelin, and adiponectin in schizophrenic patients and healthy controls.

METHODS

During a period of 2 years, we recruited 37 schizophrenic patients and 65 healthy controls. The levels of metabolic syndrome-related biomarkers including serum adiponectin, leptin, and ghrelin were measured with an enzyme-linked immunosorbent assay.

RESULTS

On applying analysis of covariance (ANCOVA) with age and body mass index adjustments, the leptin levels of schizophrenic patients (P = 0.038) were found to be higher than those of healthy controls. However, there were no significant differences in the serum levels of ghrelin or adiponectin between these two groups.

CONCLUSION

These results showed that serum leptin levels might be more sensitive than ghrelin or adiponectin levels between schizophrenic patients and healthy controls. However, studies with a large sample size are needed to confirm these results.

Effects of a 3-month supplementation with a novel soluble highly viscous polysaccharide on anthropometry and blood lipids in nondieting overweight or obese adults

BACKGROUND

High viscosity fibre is known to exert many beneficial effects on appetite and metabolism. It could potentially help in weight management, in dieting or nondieting individuals. The present study investigated the effects of the daily intake of a novel high viscosity polysaccharide (HVP) over 3 months in nondieting obese or overweight men and women.

METHODS

The study comprised a double-blind, randomised controlled clinical trial. Participants ingested 5-15 g per day of either HVP (n = 29, experimental group) or inulin (n = 30, control group) for 15 weeks. Changes in anthropometry (weight, waist and hip circumferences), blood lipids and glucose tolerance were studied from the beginning to the end of administration. Compliance and tolerance were examined.

RESULTS

Differences appeared between HVP and inulin supplementation in female participants only. Mean (SD) decreases in body weight [1.6 (3.2) kg; approximately 2% of initial weight] and hip circumference [2.8 (3.6 ) cm] occurred in women of the HVP group but not in controls (Time × Group interactions, P ≤ 0.002). Total, high-density lipoprotein and low-density lipoprotein-cholesterol were lower at the end of supplementation in the women of the HVP group compared to controls (P ≤ 0.021). No effect appeared in waist circumference and triacylglycerol. No difference was noted in the number or severity of the adverse effects reported in both groups. Adverse effects were mild and agreed with commonly reported reactions to intake of dietary fibre.

CONCLUSIONS

Beneficial although modest effects appeared after several weeks of daily HVP intake in nondieting obese or overweight women. The effects of HVP should be investigated in the context of a weight loss programme.

The approach to the mechanism of calcitonin gene-related peptide-inducing inhibition of food intake

The aim of this study was to investigate the anorectic mechanism of calcitonin gene-related peptide (CGRP) in rats. Intraperitoneal injection of CGRP (50 μg/kg) resulted in decline (p < 0.05) in the food intake of rats at 0.5, 1, 2 and 4 h in comparison with saline control. Compared with saline-treated group, the levels of hypothalamic 3',5'-cyclic adenosine monophosphate (cAMP) and plasma glucagon were increased (p < 0.05) in CGRP-treated group, but insulin level was decreased (p < 0.05). No significant changes (p > 0.05) in the plasma leptin were observed between two treatment groups. Calcitonin gene-related peptide injection down regulated (p < 0.05) both neuropeptide Y (NPY) and melanin-concentrating hormone (MCH) genes at mRNA levels, but up regulated (p < 0.05) the expression of cholecystokinin (CCK) gene. The correlations analysis showed that food intake was negatively correlated (p < 0.05) with CCK mRNA, cAMP and glucagon levels. Moreover, there existed negative correlations (p < 0.05) between MCH mRNA and glucagon levels, and positive correlations (p < 0.05) between insulin and leptin levels. The results showed that cAMP acting as the second messenger may play a vital role in the anorectic effects of CGRP. Calcitonin gene-related peptide could stimulate anorexigenic neuropeptides (i.e. CCK) and/or inhibit orexigenic neuropeptides (i.e. NPY and MCH) expression, and ultimately suppressed food intake that was functionally coupled to cAMP/PKA pathway activation.

Involvement of brain ketone bodies and the noradrenergic pathway in diabetic hyperphagia in rats

Uncontrolled type 1 diabetes leads to hyperphagia and severe ketosis. This study was conducted to test the hypothesis that ketone bodies act on the hindbrain as a starvation signal to induce diabetic hyperphagia. Injection of an inhibitor of monocarboxylate transporter 1, a ketone body transporter, into the fourth ventricle normalized the increase in food intake in streptozotocin (STZ)-induced diabetic rats. Blockade of catecholamine synthesis in the hypothalamic paraventricular nucleus (PVN) also restored food intake to normal levels in diabetic animals. On the other hand, hindbrain injection of the ketone body induced feeding, hyperglycemia, and fatty acid mobilization via increased sympathetic activity and also norepinephrine release in the PVN. This result provides evidence that hyperphagia in STZ-induced type 1 diabetes is signaled by a ketone body sensed in the hindbrain, and mediated by noradrenergic inputs to the PVN.

Metabolic imprinting by maternal protein malnourishment impairs vagal activity in adult rats

Protein restriction during lactation has been suggested to diminish parasympathetic activity, whereas sympathetic activity is enhanced in adult rats. The present study analyses whether dysfunction of the autonomic nervous system is involved in the impairment of insulin secretion from perinatally undernourished rats. Male neonates were reared by mothers fed a low- (4%) protein (LP group) or normal- (23%) protein diet (NP group). At 81 days of age, LP rats showed less body mass than NP rats (318 ± 4 g versus 370 ± 5 g) (P < 0.001). Fat tissue accumulation decreased in LP [0.8 ± 0.03 g/100 g body weight (BW)] compared to NP rats (1.1 ± 0.04 g/100 g BW) (P < 0.001). LP were glucose-intolerant as registered by the area under the curve of an i.v. glucose tolerance test (37 ± 3) compared to NP rats (29 ± 2) (P < 0.05); however, LP animals showed fasting normoglycaemia (LP, 5.0 ± 0.1; NP, 4.9 ± 0.03 mm) and hypoinsulinaemia (LP, 0.10 ± 0.02 ng/ml; NP, 0.17 ± 0.02 ng/ml). LP also showed glucose tissue uptake 60% higher than NP rats (P < 0.05). Vagus firing rate from LP was lower (7.1 ± 0.8 spikes/5 s) than that in NP rats (12.3 ± 0.7 spikes/5 s) (P < 0.001); however, there was no difference in sympathetic nervous activity. The cholinergic insulinotrophic effect was lower in pancreatic islets from LP (0.07 ± 0.01 ng/min/islet) than in NP rats (0.3 ± 0.06 ng/min/islet), whereas the levels of adrenaline-mediated inhibition of glucose-induced insulin release were similar. Perinatal protein restriction inhibited the activity of the vagus nerve, thus reducing the insulinotrophic effect of parasympathetic pathways on pancreatic β-cells, which inhibit insulin secretion.

Nonprescribed physical activity energy expenditure is maintained with structured exercise and implicates a compensatory increase in energy intake

BACKGROUND

Exercise interventions elicit only modest weight loss, which might reflect a compensatory reduction in nonprescribed physical activity energy expenditure (PAEE).

OBJECTIVE

The objective was to investigate whether there is a reduction in nonprescribed PAEE as a result of participation in a 6-mo structured exercise intervention in middle-aged men.

DESIGN

Sedentary male participants [age: 54 ± 5 y; body mass index (in kg/m²): 28 ± 3] were randomly assigned to a 6-mo progressive exercise (EX) or control (CON) group. Energy expenditure during structured exercise (prescribed PAEE) and nonprescribed PAEE were determined with the use of synchronized accelerometry and heart rate before the intervention, during the intervention (2, 9, and 18 wk), and within a 2-wk period of detraining after the intervention.

RESULTS

Structured prescribed exercise increased total PAEE and had no detrimental effect on nonprescribed PAEE. Indeed, there was a trend for greater nonprescribed PAEE in the EX group (P = 0.09). Weight loss in the EX group (-1.8 ± 2.2 kg compared with +0.2 ± 2.2 kg in the CON group, P < 0.02) reflected only ≈40% of the 300-373 kcal/kg body mass potential energy deficit from prescribed exercise. Serum leptin concentration decreased by 24% in the EX group (compared with 3% in the CON group, P < 0.03), and we estimate that this was accompanied by a compensatory increase in energy intake of ≈100 kcal/d.

CONCLUSIONS

The adoption of regular structured exercise in previously sedentary, middle-aged, and overweight men does not result in a negative compensatory reduction in nonprescribed physical activity. The less-than-predicted weight loss is likely to reflect a compensatory increase in energy intake in response to a perceived state of relative energy insufficiency.

Role of sleep duration in the regulation of glucose metabolism and appetite

Sleep curtailment has become a common behavior in modern society. This review summarizes the current laboratory evidence indicating that sleep loss may contribute to the pathophysiology of diabetes mellitus and obesity. Experimentally induced sleep loss in healthy volunteers decreases insulin sensitivity without adequate compensation in beta-cell function, resulting in impaired glucose tolerance and increased diabetes risk. Lack of sleep also down-regulates the satiety hormone leptin, up-regulates the appetite-stimulating hormone ghrelin, and increases hunger and food intake. Taken together with the epidemiologic evidence for an association between short sleep and the prevalence or incidence of diabetes mellitus and/or obesity, these results support a role for reduced sleep duration in the current epidemic of these metabolic disorders. Screening for habitual sleep patterns in patients with "diabesity" is therefore of great importance. Studies are warranted to investigate the putative therapeutic impact of extending sleep in habitual short sleepers with metabolic disorders.

The relationship among acute-phase response proteins, cytokines and hormones in cachectic patients with colon cancer

Backgraund

Acute-phase response proteins (APRP), cytokines and hormones have been claimed to be an independent prognostic factor of malignancies, however the basis for their association with prognosis remains unexplained. We suggest that in colon malignancies, as similar to pancreatic and lung cancers, changes in APRP are associated with angiogenesis.

Methods

C-reactive protein (CRP), albumin, IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, midkine, VEGF-A, VEGF-C, leptin, adiponectin, and ghrelin serum levels are studied in 126 colon cancer patients and 36 healthy subjects.

Results

We found statistically significant difference and correlations between two groups. We found significantly higher serum CRP, IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, VEGF-A, VEGF-C and leptin concentrations in patients relative to controls (p < 0.001). We found lower levels of the serum albumin, midkine, adiponectin and ghrelin in patients compared to control subjects (p < 0.001).

Conclusions

Cachexia in patients with colon cancers is associated with changes in APRP, cytokines and hormone concentrations. These biomarkers and cachexia together have a direct relationship with accelerated angiogenesis. This may lead to a connection between the outcomes in malignancies and the biomarkers.

Interval exercise alters feed intake as well as leptin and ghrelin concentrations in Standardbred mares

REASONS FOR PERFORMING STUDY

Horses in training tend to become inappetant; however, the mechanism responsible for this training-induced inappetance is not known.

HYPOTHESIS

Training and/or ulcers alter the feed intake (FI) and hormonal and/or biochemical (active ghrelin, leptin, glucose, insulin and cortisol) responses to acute high intensity exercise.

METHODS

Eight Standardbred mares underwent 3 interval exercise tests (IET) and 3 parallel control tests (CON) before (IET1) and after 8 weeks of training (IET2) and after treatment for gastric ulcers (IET3). Plasma samples were taken before (0 min), during (last 10 sec of velocities eliciting 40, 100 and 20% VO2max), and after (30 min, 60 min, 24 h) exercise (EX) or CON tests for RIA and colorimetric measurement of the concentrations of the above parameters. Samples were also collected before and after feeding. Horses were trained at a work intensity of 70% HRmax for 30 min/day, 5 days per week with FI measured daily.

RESULTS

There were no changes (P>0.05) in any variable during the parallel control trials. However, there was a mismatch between FI and digestible energy (DE) requirements (P<0.05) with EX horses not meeting their DE requirements during the post training IETs. During all IETs, ghrelin, glucose and cortisol increased (P<0.05) during EX. Leptin only increased (P<0.05) during EX in the post training IETs. Insulin remained low during EX, but increased (P<0.05) post EX.

CONCLUSION

High intensity exercise appeared to be associated with decreases in FI and alterations of leptin and ghrelin.

POTENTIAL RELEVANCE

More research is needed to determine if there is a relationship between alterations of these hormones and changes in FI in horses that lose weight while in training.

Electroacupuncture induces Fos expression in the nucleus tractus solitarius via cholecystokinin A receptor signaling in rats

OBJECTIVES

Cholecystokinin, a satiety hormone, acts on cholecystokinin A receptor on vagal afferent neurons that project to the nucleus tractus solitarius, resulting in inhibition of feeding. Cholecystokinin is known to be released by electroacupuncture stimulation at certain body sites which elicits profound psychophysiological responses. Our previous study has revealed the involvement of cholecystokinin and cholecystokinin A receptor in the electroacupuncture stimulation-induced modulation of feeding. The aim of the present study was to examine whether electroacupuncture stimulation at the acupuncture point ST36 (Joksamni) activates the nucleus tractus solitarius neurons and whether such effect is mediated by cholecystokinin A receptor.

METHODS

Using an immunofluorescent analysis of Fos, a neuronal activation marker, we compared the Fos immunoreactivity of the nucleus tractus solitarius among three groups of Sprague-Dawley rats: (1) control (48 hour fasting + saline pre-treatment + no electroacupuncture stimulation); (2) SalEA (48 hour fasting + saline pre-treatment + ST36 electroacupuncture stimulation); (3) LorEA (48 hour fasting + pre-treatment of cholecystokinin A receptor antagonist, lorglumide + ST36 electroacupuncture stimulation).

RESULTS

ST36 electroacupuncture stimulation significantly reduced 30 minute food intake (p<0.05, SalEA versus control) and increased Fos expression in the nucleus tractus solitarius (p<0.01, SalEA versus control). The effects of electroacupuncture on food intake and Fos were blocked by a lorglumide pre-treatment (p>0.05, LorEA versus control).

DISCUSSION

Our finding suggests that ST36 electroacupuncture stimulation activates the nucleus tractus solitarius neurons via cholecystokinin A receptor signaling pathway, which may be the underlying central mechanism of electroacupuncture-induced satiety effect.

Association of short sleep duration with weight gain and obesity at 1-year follow-up: a large-scale prospective study

STUDY OBJECTIVES

To investigate the association between short sleep duration and elevated body mass index (BMI) and obesity in a large sample of Japanese adults over a short period.

DESIGN

Prospective design with baseline in 2006 and 1-year follow-up.

SETTING

Workplaces of an electric power company in Japan.

PARTICIPANTS

35,247 company employees (31,477 men, 3,770 women) distributed throughout Japan.

MEASUREMENTS AND RESULTS

Measured weight and height and self-reported sleep duration were obtained at annual health checkup in 2006 and 2007. Weight change was defined as the difference in body mass index (BMI) between the baseline and 1 year later. Relative to the reference category (sleep duration 7-8 h), short sleep duration (< 5 and 5-6 h) and long sleep duration > or = 9 h were associated with an increased risk of weight gain among men after adjustment for covariates. Of the non-obese (BMI < 25) men at baseline, 5.8% became obese (BMI > or = 25) 1 year later. Higher incidence of obesity was observed among the groups with shorter sleep duration. Adjusted odds ratios for the development of obesity were 1.91 (95% CI 1.36, 2.67) and 1.50 (95% CI 1.24, 1.80) in men who slept < 5 and 5-6 h, respectively. No significant association between sleep duration and weight gain or obesity was found for women.

CONCLUSIONS

Short sleep duration was associated with weight gain and the development of obesity over 1 year in men, but not in women.

Orexin activation precedes increased NPY expression, hyperphagia, and metabolic changes in response to sleep deprivation

Several pieces of evidence support that sleep duration plays a role in body weight control. Nevertheless, it has been assumed that, after the identification of orexins (hypocretins), the molecular basis of the interaction between sleep and energy homeostasis has been provided. However, no study has verified the relationship between neuropeptide Y (NPY) and orexin changes during hyperphagia induced by sleep deprivation. In the current study we aimed to establish the time course of changes in metabolite, endocrine, and hypothalamic neuropeptide expression of Wistar rats sleep deprived by the platform method for a distinct period (from 24 to 96 h) or sleep restricted for 21 days (SR-21d). Despite changes in the stress hormones, we found no changes in food intake and body weight in the SR-21d group. However, sleep-deprived rats had a 25-35% increase in their food intake from 72 h accompanied by slight weight loss. Such changes were associated with increased hypothalamus mRNA levels of prepro-orexin (PPO) at 24 h followed by NPY at 48 h of sleep deprivation. Conversely, sleep recovery reduced the expression of both PPO and NPY, which rapidly brought the animals to a hypophagic condition. Our data also support that sleep deprivation rapidly increases energy expenditure and therefore leads to a negative energy balance and a reduction in liver glycogen and serum triacylglycerol levels despite the hyperphagia. Interestingly, such changes were associated with increased serum levels of glucagon, corticosterone, and norepinephrine, but no effects on leptin, insulin, or ghrelin were observed. In conclusion, orexin activation accounts for the myriad changes induced by sleep deprivation, especially the hyperphagia induced under stress and a negative energy balance.

Feeding regulates the expression of pancreatic genes in gastric mucosa

The ineffective short-term control of feeding behavior compromises energy homeostasis and can lead to obesity. The gastrointestinal tract secretes several regulatory peptides. However, little is known about the stomach peptide contribution to the acute regulation of intake. In an attempt to identify new gastric signals, the serial analysis of gene expression (SAGE) method was used for the transcription profiling of stomach mucosa in 7 groups of mice: fasting and sacrificed 30 minutes, 1 hour, 3 hours after a low-fat (LF) or high-fat (HF) ad libitum meal. In total, 35 genes were differentially modulated by LF and HF meals compared to fasting, including 15 mRNAs coding for digestive enzymes/secretory proteins, and 10 novel transcripts. Although the basic expression profile did not undergo substantial variations, both LF and HF meals influenced the transcription. This study represents the first global analysis of stomach transcriptome as induced by different nutritional stimuli. Further studies including the characterization of novel genes may help to identify new targets for the therapy and prevention of obesity.

Peripheral oscillators: the driving force for food-anticipatory activity

Food-anticipatory activity (FAA) and especially the food-entrained oscillator (FEO) have driven many scientists to seek their mechanisms and locations. Starting our research on FAA we, possibly like many other scientists, were convinced that clock genes held the key to the location and the underlying mechanisms for FAA. In this review, which is aimed especially at discussing the contribution of the peripheral oscillators, we have put together the accumulating evidence that the clock gene machinery as we know it today is not sufficient to explain food entrainment. We discuss the contribution of three types of oscillating processes: (i) within the suprachiasmatic nucleus (SCN), neurons capable of maintaining a 24-h oscillation in electrical activity driven by a set of clock genes; (ii) oscillations in metabolic genes and clock genes in other parts of the brain and in peripheral organs driven by the SCN or by food, which damp out after a few cycles; (iii) an FEO which, we propose, is a system built up of different oscillatory processes and consisting of an as-yet-unidentified network of central and peripheral structures. In view of the evidence that clock genes and metabolic oscillations are not essential for the persistence of FAA we propose that food entrainment is initiated by a repeated metabolic state of scarcity that drives an oscillating network of brain nuclei in interaction with peripheral oscillators. This complex may constitute the proposed FEO and is distributed in our peripheral organs as well as within the central nervous system.

Aspectos da leptina na anorexia nervosa: possíveis efeitos benéficos no tratamento da hiperatividade

Pesquisas recentes demonstram a relação direta da leptina na regulação do balanço energético e como um dos fatores envolvidos em transtornos alimentares. Com ação no sistema nervoso central, a leptina interfere na ingestão alimentar, no metabolismo da glicose, no peso corporal, na produção de hormônios sexuais e na atividade física. As pesquisas realizadas tanto em seres humanos como em animais demonstram que a queda nos níveis de leptina está relacionada aos sintomas apresentados na anorexia nervosa: a baixa ingestão alimentar, a perda excessiva de peso corporal, a amenorréia e a hiperatividade. Assim, o grau de hipoleptinemia não é apenas uma forte indicação de baixa reserva de tecido adiposo, mas também de severa desordem, sendo que os níveis de leptina podem ser utilizados para avaliar melhor a gravidade da doença. Pesquisas estão sendo realizadas com o objetivo de discutir a possibilidade de utilização da leptina como coadjuvante no tratamento de pacientes com anorexia nervosa para a diminuição da hiperatividade. Acredita-se que o tratamento com leptina associado à medicação e à psicoterapia, poderia ser benéfico em pacientes anoréxicas extremamente ativas, deixando-as mais suscetíveis ao tratamento adicional. Uma realimentação suficiente, a medicação, a psicoterapia e um ambiente acolhedor durante o tratamento com leptina devem ser assegurados. Assim, este artigo tem como objetivo discorrer sobre a leptina e aspectos relacionados à anorexia, e discutir como esta informação pode ser importante na avaliação clínica de pacientes com este transtorno alimentar.