Changes in Brain Levels of Acidic, Basic, and Neutral Amino Acids After Consumption of Single Meals Containing Various Proportions of Protein

Rats fasted overnight were allowed to consume single meals containing 0, 18, or 40% protein or continued to fast; after 2 h, brains and sera were taken and assayed for various amino acids. In general, serum levels of most amino acids were reduced by the 0% protein meal and elevated by the high-protein meal when compared with those associated with fasting conditions. Exceptions were those not diminished by the 0% protein meal (tryptophan, methionine, proline) and those increased (alanine) or decreased (glycine) by all of the test meals. Amino acids exhibiting the broadest normal ranges (estimated by comparing their serum levels after 40% protein with those after 0% protein) were tyrosine, leucine, valine, isoleucine, and proline; serum lysine and histidine, two basic amino acids, also varied more than threefold. Brain levels of lysine, histidine, and some of the large neutral amino acids (LNAAs) also exhibited clear relationships to the protein content of the test meal: those of valine, leucine, and isoleucine were depressed by the 0% protein but increased (compared with 0% protein) when protein was added to the meal: brain tyrosine was increased by all of the test meals in proportion to their protein contents; tryptophan, phenylalanine, and glutamate were increased after the 0% protein meal but not by protein-containing meals; brain lysine, histidine, and methionine were increased after the high-protein meal, and brain alanine was increased slightly by all of the meals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oral Leucine Supplementation Is Sensed by the Brain but neither Reduces Food Intake nor Induces an Anorectic Pattern of Gene Expression in the Hypothalamus

Leucine activates the intracellular mammalian target of the rapamycin (mTOR) pathway, and hypothalamic mTOR signaling regulates food intake. Although central infusion of leucine reduces food intake, it is still uncertain whether oral leucine supplementation is able to affect the hypothalamic circuits that control energy balance. We observed increased phosphorylation of p70s6k in the mouse hypothalamus after an acute oral gavage of leucine. We then assessed whether acute oral gavage of leucine induces the activation of neurons in several hypothalamic nuclei and in the brainstem. Leucine did not induce the expression of Fos in hypothalamic nuclei, but it increased the number of Fos-immunoreactive neurons in the area postrema. In addition, oral gavage of leucine acutely increased the 24 h food intake of mice. Nonetheless, chronic leucine supplementation in the drinking water did not change the food intake and the weight gain of ob/ob mice and of wild-type mice consuming a low- or a high-fat diet. We assessed the hypothalamic gene expression and observed that leucine supplementation increased the expression of enzymes (BCAT1, BCAT2 and BCKDK) that metabolize branched-chain amino acids. Despite these effects, leucine supplementation did not induce an anorectic pattern of gene expression in the hypothalamus. In conclusion, our data show that the brain is able to sense oral leucine intake. However, the food intake is not modified by chronic oral leucine supplementation. These results question the possible efficacy of leucine supplementation as an appetite suppressant to treat obesity.     

Meal Pattern Analysis of Diet‐Induced Obesity in Susceptible and Resistant Rats

Objective: To characterize the meal patterns of free feeding Sprague‐Dawley rats that become obese or resist obesity when chronically fed a high‐fat diet. Research Methods and Procedures: Male Sprague‐Dawley rats (N = 120) were weaned onto a high‐fat diet, and body weight was monitored for 19 weeks. Rats from the upper [diet‐induced obese (DIO)] and lower [diet‐resistant (DR)] deciles for body‐weight gain were selected for study. A cohort of chow‐fed (CF) rats weight‐matched to the DR group was also studied. Food intake was continuously monitored for 7 consecutive days using a BioDAQ food intake monitoring system. Results: DIO rats were obese, hyperphagic, hyperleptinemic, hyperinsulinemic, hyperglycemic, and hypertriglyceridemic relative to the DR and CF rats. The hyperphagia of DIOs was caused by an increase in meal size, not number. CF rats ate more calories than DR rats; however, this was because of an increase in meal number, not size. When expressed as a function of lean mass, CF and DR rats consumed the same amount of calories. The intermeal intervals of DIO and DR rats were similar; both were longer than CF rats. The nocturnal satiety ratio of DIO rats was significantly lower than DR and CF rats. The proportion of calories eaten during the nocturnal period did not differ among groups. Discussion: The hyperphagia of a Sprague‐Dawley rat model of chronic diet‐induced obesity is caused by an increase in meal size, not number. These results are an important step toward understanding the mechanisms underlying differences in feeding behavior of DIO and DR rats.     

Effect of One Morning Meal and a Bolus of Dexamethasone on 24‐Hour Variation of Serum Leptin Levels in Humans

Objective: We have previously shown that morning administration of dexamethasone in combination with food induces a doubling of serum leptin levels starting at 7 hours after dexamethasone administration, with a maximum effect at 10 hours, the latest time point that we have studied. However, dexamethasone given in the absence of food had no effect on serum leptin at 10 hours. The present experiment was undertaken to determine the duration of the effect of dexamethasone on 24‐hour serum leptin under fasted and fed conditions in humans. Research Methods and Procedures: Six healthy non‐obese male volunteers were studied under the following four conditions: 1) dexamethasone (2 mg intravenously, given at 0900 hours) with fasting; 2) dexamethasone with food (1700 kcal, 55% carbohydrate, 15% protein, and 30% fat, given in one meal 2 hours after dexamethasone administration at 1100 hours); 3) saline with food (same meal); 4) saline with fasting. Serum leptin, glucose, insulin, and cortisol were monitored every 30 minutes for 24 hours. Results: 1) Under the fasting condition, dexamethasone increased leptin nocturnal secretion between 2100 and 2400 hours. 2) A single meal (1700 kcal) at 1100 hours increased nocturnal leptin secretion when compared with the fasting condition. The peak increase of leptin was 123% over baseline between 2100 and 2400 hours, 10 to 14 hours after the meal. 3) In the fed + dexamethasone condition, leptin levels increased from baseline starting 8 hours after dexamethasone injection, reached a maximum increase of 260% between 2100 and 2400 hours, then decreased thereafter, remaining elevated compared to baseline for 16 hours. There was a correlation between 24‐hour leptin secretion and insulin secretion after a single morning meal. Discussion: A single bolus of dexamethasone, given before a single large meal, produces a delayed (6‐hour) but long‐lasting increase in serum leptin (over 16 hours). Under fasted conditions, dexamethasone does not increase daytime leptin but does increase leptin during the night.     

Diurnal Changes in Blood Metabolites and Their Relation to Plasma Growth Hormone and Time of Feeding in Mithun Heifers (Bos frontalis)

The aim of the present study was to investigate what, if any, diurnal changes occur in blood metabolites in relation to plasma growth hormone (GH) and feeding time among mithun (Bos frontalis), a semi‐wild ruminant. Blood samples were collected at hourly intervals during a 24 h span from 6 mithun heifers (averaging 2.5 yr of age and averaging 230 kg in weight) that were fed twice a day at 11:00 and 16:00 h. Samples were assayed for plasma GH and blood metabolites, non‐esterified fatty acids (NEFA), glucose, and alpha‐amino nitrogen. The total sampling period was divided into a 1) postprandial (after meal) period (period I: 11:00 to 21:00 h) and 2) interprandial period (period II: 22:00 to 10:00 h) and also into night (20:00 to 05:00 h) and day (06:00 to 10:00 h) periods for statistical analysis. Plasma glucose and alpha‐amino nitrogen levels increased (p<0.01), and plasma NEFA and GH decreased (p<0.01) after each meal. No diurnal rhythmicity was detected in plasma glucose or alpha‐amino nitrogen levels. Interestingly, plasma NEFA and GH levels were higher (p<0.01) during the interprandial (period II) and night periods, indicating an energy deficit that occurred progressively during the interprandial period of nocturnal feed deprivation. In twice‐daily‐fed mithuns we conclude that: 1) plasma metabolites and GH exhibited a definite pattern of change with time of feeding; 2) concentrations of plasma NEFA were higher nocturnally due to an energy deficit and that GH levels were higher during the interprandial period after the second meal; 3) the interprandial period after the second feeding may be considered to constitute a short‐term food deprivation; 4) the longer interprandial period of 19 h in this study between the second and subsequent morning meal may be changed into equally divided feedings to minimize the short‐term energy deficit; and 5) blood sampling for blood metabolites in mithuns should be conducted at a fixed time of day with special emphasis on time of feeding.     

The effect of mono‐amino acids on larval settlement of the barnacle,Balanus amphitrite Darwin

Settlement of barnacle larvae is believed to be induced by the chemical cues present in their surrounding environment. Here, an investigation was carried out on the effects of sixteen different mono‐amino acids with acidic, basic, uncharged polar and nonpolar side chains, and GABA on larval settlement of the barnacle, Balanus amphitrite. Settlement inducing activity by nine mono‐amino acids, viz. asparagine, glutamine, tyrosine, serine, glycine, tryptophan, leucine, isoleucine and valine (but not phenylalanine) with uncharged polar and nonpolar side chains was observed. Of these, the most active mono‐amino acids were serine, leucine and isoleucine, which were effective at a threshhold of 1.0 × 10^‐7 M. On the other hand, aspartic acid, glutamic acid, GABA, and the basic mono‐amino acids lysine, arginine and histidine did not have any inducing effect. These results suggest that uncharged polar and non‐polar end group of the amino acid chain play an important role in inducing the settlement process in cyprids.     

Circadian Eating and Sleeping Patterns in the Night Eating Syndrome

Objective: To compare the eating and sleep‐wake patterns of persons with the night eating syndrome (NES) with those of matched control subjects. Research Methods and Procedures: Forty‐six overweight/obese NES subjects (mean age 43.3 ± 9.8 years; 32 women) and 43 similar controls (mean age 39.0 ± 11.0 years; 28 women) wore wrist actigraphs for 7 days and completed sleep and food diaries at home. Results: There was no difference between the total energy intake of the NES and the control subjects, but the pattern of energy intake differed greatly. Relative to control subjects, the temporal pattern of food intake of night eaters was delayed. Food intake after the evening meal, as a proportion of the 24‐hour intake, was more than 3‐fold greater in NES subjects than in controls (34.6 ± 10.1% vs. 10.0 ± 6.9%, p = 0.001). NES subjects had sleep onset, offset, and total sleep duration times comparable with those of controls. NES subjects reported more nocturnal awakenings than did controls (1.5 ± 1.0 per night vs. 0.5 ± 0.5; p < 0.001), and their actigraphically monitored arousals occurred earlier during sleep (at 128 minutes after sleep onset vs. 193 minutes, p = 0.01). NES subjects consumed food on 74% of the awakenings vs. 0% for the controls. Discussion: The pattern of cumulative energy intake of the night eaters suggests a phase delay in energy consumption relative to sleep‐wake times. NES may involve a dissociation of the circadian control of eating relative to sleep.     

Diet quality influences isotopic discrimination among amino acids in an aquatic vertebrate

Stable nitrogen isotopic composition of amino acids (δ¹⁵N_AA) has recently been employed as a powerful tool in ecological food web studies, particularly for estimating the trophic position (TP) of animal species in food webs. However, the validity of these estimates depends on the consistency of the trophic discrimination factor (TDF; = Δδ¹⁵N_AA at each shift of trophic level) among a suite of amino acids within the tissues of consumer species. In this study, we determined the TDF values of amino acids in tadpoles (the Japanese toad, Bufo japonicus) reared exclusively on one of three diets that differed in nutritional quality. The diets were commercial fish‐food pellets (plant and animal biomass), bloodworms (animal biomass), and boiled white rice (plant carbohydrate), representing a balanced, protein‐rich, and protein‐poor diet, respectively. The TDF values of two “source amino acids” (Src‐AAs), methionine and phenylalanine, were close to zero (0.3–0.5‰) among the three diets, typifying the values reported in the literature (~0.5‰ and ~0.4‰, respectively). However, TDF values of “trophic amino acids” (Tr‐AAs) including alanine, valine, leucine, isoleucine, and glutamic acid varied by diet: for example, the glutamic acid TDF was similar to the standard value (~8.0‰) when tadpoles were fed either the commercial pellets (8.0‰) or bloodworms (7.9‰), but when they were fed boiled rice, the TDF was significantly reduced (0.6‰). These results suggest that a profound lack of dietary protein may alter the TDF values of glutamic acid (and other Tr‐AAs and glycine) within consumer species, but not the two Src‐AAs (i.e., methionine and phenylalanine). Knowledge of how a nutritionally poor diet can influence the TDF of Tr‐ and Src‐AAs will allow amino acid isotopic analyses to better estimate TP among free‐roaming animals.     

The effects of dietary protein:energy ratio and amino acid pattern on nitrogen utilization and excretion of rainbow trout Oncorhynchus mykiss (Walbaum)

This study was undertaken to investigate: (1) the effects of both deficiencies and excesses in essential amino acids (EAAs) from an estimated optimum dietary EAA pattern on nitrogen (N) utilization and excretion of rainbow trout Oncorhynchus mykiss, (2) the effects of dietary digestible protein (P_D): digestible energy (E_D) ratio (P_D:E_D) on N utilization and excretion of O. mykiss and (3) the potential interaction of these two factors. A 3 × 3 factorial experiment was conducted, with the two factors EAA pattern and P_D:E_D ratio. The three levels of EAA pattern were: (1) optimum EAA pattern, (2) 60% deficiencies in the three amino acids arginine, histidine and lysine, and (3) 60% excesses in the three amino acids arginine, histidine and leucine. The three levels of P_D:E_D ratio were 18, 21 and 24 g MJ^?1. Amino acid deficiencies from an optimum amino acid pattern caused reductions in mean N retention of 29 to 37%, with the greatest reduction associated with the lowest P_D:E_D ratio, and similar substantial increases in total N and ammonia‐N excretion at all of the dietary P_D:E_D ratios investigated. Amino acid excesses, however, did not negatively affect N retention or excretion. Increasing P_D:E_D ratio was associated with decreasing N retention and increasing N excretion over the range of dietary protein and lipid levels tested. Results of this study showed that a diet with optimum dietary amino acid pattern and lowest P_D:E_D ratio produced the highest N retention (47% of ingested N) and the lowest total N and ammonia‐N excretion of O. mykiss.     

Effects of a Longitudinal Training Program on Responses to Exercise in Overweight Men

Objective: The aim of this study was to determine how training modifies metabolic responses and lipid oxidation in overweight young male subjects. Research Methods and Procedures: Eleven overweight subjects were selected for a 4‐month endurance training program. Before and after the training period, they cycled for 60 minutes at 50% of their Vo ₂max after an overnight fast or 3 hours after eating a standardized meal. Various metabolic and endocrine parameters, and respiratory exchange ratio values were evaluated. Results: Exercise‐induced plasma norepinephrine concentration increases were similar before and after training in fasted or fed conditions. After food intake, exercise promoted a decrease in plasma glucose and a higher increase in epinephrine than in fasting conditions. The increase in epinephrine after the meal was more marked after training (264 ± 32 vs. 195 ± 35 pg/mL). Training lowered the resting plasma nonesterified fatty acids. During exercise, changes in glycerol were similar to those found before training. Lipid oxidation during exercise was higher in fasting than in fed conditions (15.5 ± 1.4 vs. 22.3 ± 1.7 g/h). Training did not significantly increase fat oxidation when exercise was performed in fed conditions, but it did in fasting conditions (18.6 ± 1.4 vs. 27.2 ± 1.8 g/h). Discussion: Endurance training decreased plasma nonesterified fatty acids, cholesterol, and insulin concentrations. Training increased lipid oxidation during exercise, in fasting conditions, and not when exercise was performed after the meal. During exercise in overweight subjects, the fasting condition seems more suited to oxidizing fat and maintaining glucose homeostasis than a 3‐hour wait after a standard meal.     

Meat meal in the diet of the early-weaned pig IV. The supplementation of diets with tryptophane,lysine and methionine

Two experiments were conducted with 72 pigs between 28 and 56 days of age to study the effect of tryptophane supplementation on their performance when fed on diets containing wheat and meat meal.In the first experiment, pigs were fed on a basal diet (Diet 1) or on the same diet supplemented with calcium dihydrogen phosphate (Diet 2), bone meal (Diet 3) or bone meal plus tryptophane (Diet 4), all to 3.1% calcium. The weight gains of the pigs (315 g day^?1) fed on Diet 3 were significantly lower than that of the pigs fed on the other three diets (363 g day^?1). The feed conversion ratios showed a similar trend. Diet 3 contained 0.16% tryptophane while the other diets contained 0.18–0.19% tryptophane. The crude protein, lysine and methionine contents of all diets were similar.In the second experiment, a basal diet containing meat meal and bone meal was supplemented with tryptophane, lysine plus methionine or all three amino acids. Feed intake was increased by all amino acid supplements. Weight gains were improved significantly (57%) by the addition of all three amino acids to the diets, but the improvements due to tryptophane alone (28%) or methionine plus lysine (35%) were not significant. Tryptophane supplementation alone or with lysine plus methionine increased the nitrogen retention of the pigs.It was concluded that the requirement for tryptophane of pigs between 28 and 56 days of age was greater than 0.16% of diets containing wheat and meat meal.     

Feeding by sugarcane aphid,Melanaphis sacchari,on sugarcane cultivars with differential susceptibility and potential mechanism of resistance

Feeding behavior of Melanaphis sacchari Zehntner (Hemiptera: Aphididae) was studied on sugarcane, Saccharum spp. (Poaceae), cultivars HoCP 91‐555 (resistant), LCP 85‐384 (moderately resistant), and L 97‐128 (susceptible) using the electrical penetration graph (EPG) technique. Constitutive concentrations of total phenolics and available carbohydrates, water potential at the whole‐leaf tissue level, and free amino acids (FAAs) in phloem sap extracts, and in honeydew produced by aphids fed on L 97‐128 and HoCP 91‐555 were determined. Cultivar did not influence time for M. sacchari to access phloem sieve elements. Total time in sieve elements was ca. two‐fold greater on L 97‐128 than on HoCP 91‐555, whereas it did not differ from LCP 85‐384 in either cultivar. The mean duration of individual events associated with phloem sap ingestion was ca. 50% shorter on both HoCP 91‐555 and LCP 85‐384 than on L 97‐128. Although cultivar effects were not detected for levels of total phenolics, available carbohydrates, and water potential, two free essential amino acids, histidine and arginine, were absent from phloem sap in HoCP 91‐555. Two free essential amino acids, leucine and isoleucine, and two free non‐essential amino acids, tyrosine and proline, were absent from honeydew of aphids fed on HoCP 91‐555. These results suggest that despite apparent biosynthesis of some FAAs, the absence of important FAAs in the phloem sap of HoCP 91‐555 and the inability of M. sacchari and its endosymbionts (e.g., Buchnera) to derive specific free essential and non‐essential amino acids from other ingested molecules, possibly along with other unidentified factors, underlie the pest's decreased phloem sap ingestion and consequently reduced growth potential on HoCP 91‐555.     

The role of free amino acids in semen of rainbow trout Oncorhynchus mykiss and carp Cyprinus carpio

The present study investigated (1) the free amino acid (FAA) composition in semen of rainbow trout Oncorhynchus mykiss and carp Cyprinus carpio, (2) enzyme systems involved in amino acid metabolism and (3) the effect of amino acids on sperm viability under in vitro storage conditions. In the seminal plasma of O. mykiss, the main FAAs were arginine, glutamic acid, isoleucine, leucine, methionine and proline, in spermatozoa cysteine, arginine and methionine. In the seminal plasma of C. carpio, the main FAAs were alanine, arginine, cysteine, glutamic acid, histidine, leucine, lysine, methionine and proline, in spermatozoa arginine, glutamic acid, histidine, leucine and lysine. When spermatozoa were incubated for 48 h together with the seminal plasma, the quantitative amino acid pattern changed in both species indicating their metabolism. In spermatozoa and seminal plasma of O. mykiss and C. carpio, the following enzymes were found to be related to amino acid metabolism: transaminases (specific for alanine, aspartate, isoleucine and leucine), decarboxylases (specific for valine and lysine), glutamate dehydrogenase and α‐keto acid dehydrogenases (substrates: 3‐methyl‐2‐oxovaleric acid and 4‐methyl‐2‐oxovalerate). These data demonstrate that amino acid catabolism by transamination, decarboxylation and oxidative deamination can occur in semen of the two species. Also activity of methionine sulphoxide reductase was detected, an enzyme which reduces methionine sulphoxide to methionine. This reaction plays an important role in antioxidant defence. To determine the effect of FAAs on the sperm viability, C. carpio and O. mykiss spermatozoa were incubated in sperm motility inhibiting saline solution containing different amino acids. Methionine had a positive effect on the sperm viability in both species. Taken together this result with the in vivo occurrence of methionine and of methionine reductase in semen, it can be assumed that this amino acid plays an important role in antioxidant defence. Also isoleucine in O. mykiss and leucine in C. carpio had a positive effect on sperm viability. As seminal plasma and spermatozoa of the two species exhibit enzyme activities to catabolize leucine and isoleucine, they might serve as additional energy resources especially during prolonged incubation and storage periods.     

Effect of central and peripheral leucine on energy metabolism in the Djungarian hamster (Phodopus sungorus)

Branched-chain amino acids, particularly leucine, are thought to activate nutrient sensing pathways in the hypothalamus that regulate food intake and energy homeostasis. In the light of recent controversial findings of leucine’s effect on energy homeostasis further clarification of the metabolic impact of dietary leucine supplementation is required. We examined the pharmacological and dietary effects of leucine on energy metabolism in the Djungarian hamster (Phodopus sungorus), a well-established model for studies of alterations in leptin sensitivity and energy metabolism. We acutely administered leucine into the lateral ventricle (1.1 μg) of hamsters to characterize whether leucine exhibits anorexigenic properties in this species as has been described in other rodents. Next the catabolic effect of dietary administered leucine via supplemented rodent diet (15 % leucine), drinking water (17 g/L leucine) and oral gavages (10 mg/day); as well as the effect of subcutaneously (0.1 and 3 mg/day) and intraperitoneally (0.1, 3 and 6 mg/day) injected leucine which avoids the gastrointestinal-track was analyzed. Centrally administered leucine reduced 24 h food intake (by 32 %) and body weight. Both parameters were also reduced in hamsters with leucine supplemented diet, but this catabolic response was based on a pronounced taste aversion to the leucine-diet. In all other experiments, dietary leucine and peripheral injections of leucine had no effect on food intake, body weight and basal blood glucose levels. Our data suggest that in the Djungarian hamster dietary leucine fails to exhibit catabolic effects that would override the evolutionary conserved adaptations of the species which is critical for its survival.     

Inverse relationship between protein intake and plasma free amino acids in healthy men at physical exercise

The effect of a "normal" (n = 8) and "high" (n = 6) protein intake (1 and 2.5 g x kg(-1) x day(-1), respectively) and of exercise on plasma amino acid (AA) concentrations, insulin, and glucagon concentrations was followed throughout a continuous 24-h period in adult male subjects at energy balance after six days on a standardized diet and exercise program. Subjects were fasting from 2100 on day 6 to 1200 on day 7 and then fed 10 identical meals hourly until 2100. Physical exercise was performed (46% maximal oxygen uptake) between 0830 and 1000 (fasting) and in a fed state (1600-1730) on each day. The normal-protein group showed fasting plasma AA concentrations that were higher (P < 0.05) than those for the high-protein group, except for leucine, methionine, and tyrosine. Glutamine, glycine, alanine, taurine, and threonine concentrations were distinctly higher ( approximately 30% or greater) throughout the 24-h period in subjects consuming the normal- vs. the high-protein diets. Exercise appeared to increase, although not profoundly, the plasma concentrations of amino acids except for glutamate, histidine, ornithine, and tryptophan. The profound diet-related differences in plasma AA concentrations are only partially explained by differences in the renal clearance of the amino acids. We speculate on the possible metabolic basis for these findings.     

Postprandial variations of plasma inflammatory markers in abdominally obese men

Objective: Abdominal obesity is associated with a fasting proinflammatory condition. However, not much is known of the potential variations in circulating inflammatory markers after food intake. The purpose of the present study was to examine postprandial changes in plasma tumor necrosis factor (TNF)‐α, interleukin (IL)‐6, and C‐reactive protein (CRP) concentrations in men and their potential associations with fat distribution and metabolic profile variables. Research Methods and Procedures: Thirty‐eight men were given a high‐fat meal in the morning after an overnight fast, and TNF‐α, IL‐6, and CRP levels were measured in plasma at 0, 4, and 8 hours after the meal. Physical and metabolic profiles were also assessed for each participant. Results: We observed a substantial increase in circulating IL‐6 levels (p < 0.0001) after the meal. Although postprandial variations in circulating TNF‐α levels across time failed to reach statistical significance (p = 0.02), we noted a significant decrease in plasma TNF‐α concentrations 4 hours (?10%, p < 0.001 vs. 0 hours) after food intake. Plasma CRP levels were not affected by the fat load. We also noted that insulin‐sensitive individuals displayed a less pronounced inflammatory response after food intake than insulin‐resistant subjects. Discussion: Results of the present study show that consumption of a high‐fat meal leads to an increase in plasma IL‐6 concentrations and transient decrease in circulating TNF‐α levels in overweight men. Our results suggest a possible role of insulin resistance in the modulation of the postprandial inflammatory response, which could, in turn, contribute to worsen the state of insulin resistance.     

Why water birds forage at night: a test using black‐tailed godwits Limosa limosa during migratory periods

Many migratory water birds are known to feed both during day and night outside the breeding season, but the underlying factors and mechanisms determining this foraging pattern are poorly understood. We addressed this topic by comparing both diurnal and nocturnal foraging activity (FA) and metabolizable energy intake rate (MEIR) in migrating black‐tailed godwits Limosa limosa staging in two different habitats, rice fields and coastal salt pans. Black‐tailed godwits staging in rice fields during pre‐breeding migration fed on rice seeds, and only foraged during the daylight period (FA: 81.89 ± 3.03%; MEIR: 1.15 ± 0.03 kJ · min^?1). Daily energy consumption (DEC) of godwits relying on seeds was enough to meet the theoretical daily energy expenditure (DEE). In contrast, black‐tailed godwits staging in salt pans during post‐breeding migration fed on chironomid larvae, and they foraged during both daylight (FA: 67.36 ± 4.30%; MEIR: 0.27 ± 0.01 kJ · min^?1) and darkness (FA: 69.89 ± 6.89%; MEIR: 0.26 ± 0.00 kJ · min^?1). Nocturnal energy intake contributed 31.7% to DEC, the latter being insufficient to fully meet DEE. Our findings give empirical support to the view that diurnal foraging is the norm in many migratory water birds outside the breeding season, and nocturnal foraging occurs when the daily energy requirements are not met during the daylight period, supporting the supplementary food hypothesis.     

Preproghrelin-derived peptide, obestatin, fails to influence food intake in lean or obese rodents

Objectives: Obestatin has been initially characterized as a new peptide derived from the ghrelin precursor, which suppresses food intake and inhibits the orexigenic and prokinetic actions of ghrelin when injected peripherally or centrally in lean mice. However, reproducing these data remains controversial. Reasons for the disparity may be the use of different doses, routes, and animal models. We aimed to investigate the effects of peripheral and intracisternal (IC) injection of obestatin on feeding, gastric motility, and blood glucose in rats as well as in diet‐induced obese (DIO) mice. Research Methods and Procedures: Food intake and gastric emptying of a semi‐liquid caloric meal were measured after intraperitoneal (IP) injection of obestatin in rats and DIO mice. Gastric phasic motility and blood glucose were monitored in urethane‐anesthetized rats after IC or intravenous (IV) injection of obestatin. Results: Obestatin injected intraperitoneally at doses ranging from 0.1 to 3 mg/kg influenced neither acute food intake nor gastric emptying in rats. Obestatin injected intravenously at 0.3 or 3 mg/kg and IC at 7.5 or 30 µg/rat modified neither fasted gastric phasic motility nor blood glucose levels, while ghrelin (30 µg/kg, IV) increased and vagotomy suppressed gastric motility, and an oligosomatostatin analog (3 µg/rat, IC) decreased blood glucose. Obestatin, injected intraperitoneally (0.3 mg/kg) in DIO mice, did not alter feeding response to a fast, while urocortin 1 (10 µg/kg, IP) induced a 73.3% inhibition at 2 hours. Discussion: Our data demonstrate that peripheral administration of obestatin did not modify food intake in rats or obese mice or gastric motor function in rats.