Food Intake In Rodents Research Articles

Central administered xenin induced Fos expression in nesfatin-1 neurons in rats

Xenin is a 25-amino acid peptide identified in human gastric mucosa, which is widely expressed in peripheral and central tissues. It is known that the central or peripheral administration of xenin decreases food intake in rodents. Nesfatin-1/NUCB2 (nesfatin-1) has been identified as an anorexic neuropeptide, it is often found co-localized with many peptides in the central nervous system. After the intracerebroventricular administration of xenin on nesfain-1-like immunoreactivity (LI) neurons, we examined its effects on food intake and water intake in rats. As a result, Fos-LI neurons were observed in the organum vasculosum of the laminae terminalis (OVLT), the median preoptic nucleus (MnPO), the subfornical organ (SFO), the supraoptic nucleus (SON), the paraventricular nucleus (PVN), the arcuate nucleus (Arc), the lateral hypothalamic area (LHA), the central amygdaloid nucleus (CAN), the dorsal raphe nucleus (DR), the locus coeruleus (LC), the area postrema (AP) and the nucleus of the solitary tract (NTS). After the administration, the number of Fos-LI neurons was significantly increased in the LC and the OVLT, the MnPO, the SFO, the SON, the PVN, the Arc, the LHA, the CAN, the DR, the AP and the NTS, compared with the control group. After the administration of xenin, we conducted double immunohistochemistry for Fos and nesfatin-1, and found that the number of nesfatin-1-LI neurons expressing Fos were significantly increased in the SON, the PVN, the Arc, the LHA, the CAN, the DR, the AP and the NTS, compared with the control group. The pretreatment of nesfatin-1 antisense significantly attenuated this xenin-induced feeding suppression, while that of nesfatin-1 missense showed no improvement. These results indicate that central administered xenin may have anorexia effects associated with activated central nesfatin-1 neurons.

Dietary medium-chain fatty acids reduce food intake via the GDF15-GFRAL axis in mice

ObjectiveMedium chain fatty acids (MCFAs), which are fatty acids with chain lengths of 8–12 carbon atoms, have been shown to reduce food intake in rodents and humans, but the underlying mechanisms are unknown. Unlike most other fatty acids, MCFAs are absorbed from the intestine into the portal vein and enter first the liver. We thus hypothesized that MCFAs trigger the release of hepatic factors that reduce appetite. MethodsThe liver transcriptome in mice that were orally administered MCFAs as C8:0 triacylglycerol (TG) was analyzed. Circulating growth/differentiation factor 15 (GDF15), tissue Gdf15 mRNA and food intake were investigated after acute oral gavage of MCFAs as C8:0 or C10:0 TG in mice. Effects of acute and subchronic administration of MCFAs as C8:0 TG on food intake and body weight were determined in mice lacking either the receptor for GDF15, GDNF Family Receptor Alpha Like (GFRAL), or GDF15. ResultsHepatic and small intestinal expression of Gdf15 and circulating GDF15 increased after ingestion of MCFAs, while intake of typical dietary long-chain fatty acids (LCFAs) had no effect. Plasma GDF15 levels also increased in the portal vein with MCFA intake, indicating that in addition to the liver, the small intestine contributes to the rise in circulating GDF15. Acute oral provision of MCFAs decreased food intake over 24 h compared with a LCFA-containing bolus, and this anorectic effect required the GDF15 receptor, GFRAL. Moreover, subchronic oral administration of MCFAs reduced body weight over 7 days, an effect that was blunted in mice lacking either GDF15 or GFRAL. ConclusionsWe have identified ingestion of MCFAs as a novel nutritional approach that increases circulating GDF15 in mice and have revealed that the GDF15-GFRAL axis is required for the full anorectic effect of MCFAs.

Postprandial Increases in Liver-Gut Hormone LEAP2 Correlate with Attenuated Eating Behavior in Adults Without Obesity.

The novel liver-gut hormone liver-expressed antimicrobial peptide-2 (LEAP2) is a centrally acting inverse agonist, and competitive antagonist of orexigenic acyl ghrelin (AG), at the GH secretagogue receptor, reducing food intake in rodents. In humans, the effects of LEAP2 on eating behavior and mechanisms behind the postprandial increase in LEAP2 are unclear, though this is reciprocal to the postprandial decrease in plasma AG. Plasma LEAP2 was measured in a secondary analysis of a previous study. Twenty-two adults without obesity attended after an overnight fast, consuming a 730-kcal meal without or with subcutaneous AG administration. Postprandial changes in plasma LEAP2 were correlated with postprandial changes in appetite, high-energy (HE) or low-energy (LE) food cue reactivity using functional magnetic resonance imaging, ad libitum food intake, and plasma/serum AG, glucose, insulin, and triglycerides. Postprandial plasma LEAP2 increased by 24.5% to 52.2% at 70 to 150 minutes, but was unchanged by exogenous AG administration. Postprandial increases in LEAP2 correlated positively with postprandial decreases in appetite, and cue reactivity to HE/LE and HE food in anteroposterior cingulate cortex, paracingulate cortex, frontal pole, and middle frontal gyrus, with similar trend for food intake. Postprandial increases in LEAP2 correlated negatively with body mass index, but did not correlate positively with increases in glucose, insulin, or triglycerides, nor decreases in AG. These correlational findings are consistent with a role for postprandial increases in plasma LEAP2 in suppressing human eating behavior in adults without obesity. Postprandial increases in plasma LEAP2 are unrelated to changes in plasma AG and the mediator(s) remain uncertain.

Expression of Neurotensin and Its Receptors Along the Intestinal Tract in Type 2 Diabetes Patients and Healthy Controls.

Enteroendocrine N cells secrete neurotensin (NTS). NTS reduces food intake in rodents and may increase insulin release. In humans, postprandial NTS responses increase following Roux-en-Y gastric bypass, associating the hormone with the glucose- and body weight-lowering effects of these procedures. We looked at N cell density and mucosal messenger RNA (mRNA) expression profiles of NTS and NTS receptors in type 2 diabetes (T2D) patients and healthy controls. Using double-balloon enteroscopy, 12 patients with T2D and 12 sex-, age-, and body mass index-matched healthy controls had mucosa biopsies taken from the entire length of the small intestine (at 30-cm intervals) and from 7 anatomically well-defined locations in the large intestine. Biopsies were analyzed using immunohistochemistry and mRNA sequencing. N cell density and NTS mRNA expression gradually increased from the duodenum to the ileum, while negligible NTS-positive cells and NTS mRNA expression were observed in the large intestine. NTS receptor 1 and 2 mRNA expression were not detected, but sortilin, a single-pass transmembrane neuropeptide receptor of which NTS also is a ligand, was uniformly expressed in the intestines. Patients with T2D exhibited lower levels of NTS-positive cells and mRNA expression than healthy controls, but this was not statistically significant after adjusting for multiple testing. This unique intestinal mapping of N cell density and NTS expression shows increasing levels from the small intestine's proximal to distal end (without differences between patients with T2D and healthy controls), while negligible N-cells and NTS mRNA expression were observed in the large intestine. Sortilin was expressed throughout the intestines in both groups; no NTS receptor 1 or 2 mRNA expression were detected.

Intermittent fasting increases growth differentiation factor 15 in females with overweight or obesity but not associated with food intake

Growth differentiation factor 15 (GDF15) increases with acute fast in animals, and high GDF15 reduces food intake in rodents. We explored whether GDF15 was altered following intermittent fasting (IF) versus caloric restriction (CR), and associations with energy intake. Females with obesity received all foods at 70% (IF70 and CR70) or 100% of energy requirements for 8 weeks. IF ate 2–9% less than provided on refeeding days, resulting in greater weight losses. GDF15 was increased 5% more in IF70 versus CR70, but not associated with energy intake. This rise in GDF15 is unlikely to explain restriction of energy intake during IF.

Does clozapine affect the discriminative stimulus effects of food deprivation in rats trained to discriminate between 2 and 22 hours food deprivation?

In humans, weight gain is a side effect of several atypical antipsychotics. Previous research with rodents indicates clozapine may increase food consumption for the first 2‐4 hours after injection (Antelman et al. 1977; Benvenga & Leander 1997; Lee & Clifton 2002) as well as increase motivation to acquire food under a progressive ratio schedule (Abela et al. 2020; Loh et al. 1992; Mobini et al. 2000). In other studies, however, clozapine has been shown to reduce response rates in lever pressing operant procedures (Ford et al., 1997; Kaempf & Porter, 1997; Varvel et al., 2002; Wiley et al., 1994; Abela 2020) and decrease food intake in rodents (Baptista et al., 1993). The current study investigated if clozapine would affect the discriminative stimulus effects of food deprivation. Male, Sprague‐Dawley rats (n = 11) were trained to discriminate 22 hrs of food deprivation from 2 hrs of food deprivation in a two‐lever, operant choice task. Rats were trained to respond on the right lever after 2 hrs of food deprivation to earn a 45 mg food pellet under an FR 15 schedule. Left lever presses were punished with 8 seconds of darkness. Under 22 hr deprivation conditions, the contingencies were reversed (left lever presses were reinforced with food delivery and right lever presses resulted in 8 seconds of darkness). Training sessions lasted until subjects earned 10 reinforcers or 15 minutes elapsed. Acquisition of discrimination was defined as 80% or greater condition appropriate responding both before the first reinforcer was earned and for the entire session for 8 out of 10 consecutive days. After acquiring the discrimination, subjects were food deprived for 2 or 22 hrs and administered clozapine (1.0 ‐ 5.6 mg/kg, s.c.). or vehicle (30% DMSO; 1.0 ml/kg, s.c.). During test sessions, responses toward either lever were reinforced under the FR 15. The session lasted until subjects earned 5 reinforcers or 5 minutes elapsed, whichever occurred first. The discriminative stimulus effects of food deprivation and response rates were assessed every 15 min for the succeeding 2 hrs. After test sessions, each subjects’ food intake was recorded for 1 hour. Clozapine had no effect on the discriminative stimulus effects of 2 hr deprivation, however, clozapine (1.0 ‐ 5.6 mg/kg) significantly decreased response rates. After 22 hrs food deprivation, clozapine (1.0 ‐ 5.6 mg/kg) significantly decreased % 22 hr deprivation‐appropriate responding. Response rates were significantly increased by 1.0 mg/kg clozapine, whereas response rates were decreased by 5.6 mg/kg clozapine compared to rates of responding following 30% DMSO. Clozapine (3.2 ‐ 5.6 mg/kg) decreased food intake in rats under both food deprivation conditions. These data provide further support for the notion that clozapine decreases feeding‐related behaviors in rats.

Neurotensin secretion after Roux-en-Y gastric bypass, sleeve gastrectomy, and truncal vagotomy with pyloroplasty.

Neurotensin (NT) is released from enteroendocrine cells and lowers food intake in rodents. We evaluated postprandial NT secretion in humans after surgeries associated with accelerated small intestinal nutrient delivery, and after Roux-en-Y gastric bypass (RYGB) when glucagon-like peptide-1 (GLP-1) signalling and dipeptidyl peptidase 4 (DPP-4) were inhibited, and during pharmacological treatments influencing entero-pancreatic functions. We measured NT concentrations in plasma from meal studies: (I) after truncal vagotomy with pyloroplasty (TVP), cardia resection +TVP (CTVP), and matched controls (n=10); (II) after RYGB, sleeve gastrectomy (SG), and in matched controls (n=12); (III) after RYGB (n=11) with antagonism of GLP-1signalling using exendin(9-39) and DPP-4 inhibition using sitagliptin; (IV) after RYGB (n=11) during a run-in period and subsequent treatment with, sitagliptin, liraglutide (GLP-1 receptor agonist), verapamil (calcium antagonist), acarbose (alpha glucosidase inhibitor), and pasireotide (somatostatin analogue), respectively. (I) NT secretion was similar after TVP/CTVP (p=0.9), but increased vs. controls (p<0.0001). (II) NT secretion was increased after RYGB vs. SG and controls (p<0.0001). NT responses were similar in SG and controls (p=0.3), but early postprandial NT concentrations were higher after SG (p<0.05). (III) Exendin (9-39) and sitagliptin did not change NT responses vs placebo (p>0.2), but responses were lower during sitagliptin vs. exendin(9-39) (p=0.03). (IV) Pasireotide suppressed NT secretion (p=0.004). Sitagliptin tended to lower NT secretion (p=0.08). Liraglutide, verapamil, and acarbose had no effect (p>0.9). Neurotensin secretion is increased after surgeries associated with accelerated gastric emptying and lowered by pasireotide.

Environmental Enrichment Potentiates Glucose-Induced Anorexia in Mice

The hypothalamus controls food intake and metabolism by integrating nutrient and hormonal signals from peripheral tissues. Both central and peripheral administration of glucose leads to a reduction in food intake in rodents. Similarly, administration of the adipocyte hormone leptin or the gastrointestinal hormone xenin reduces food intake. In contrast, impairments in hypothalamic signaling of these factors cause hyperphagia and obesity in rodents and humans. Environmental factors affect behavior including feeding behavior and energy metabolism in rodents and humans. Studies have found that environmental enrichment (EE), in which mice interact with complex sensory and motor stimulation, led to a significant reduction in adiposity and resistance to diet-induced obesity in mice. This effect is independent of energy expenditure and is associated with enhanced hypothalamic signaling, but the exact mechanism is unknown. We hypothesized that EE potentiates the feeding suppressing effects of anorectic signals. To address this hypothesis, 4-week-old male C57BL/6 mice were group housed (5/cage) under standard laboratory conditions or EE conditions with free access to regular rodent chow and feeding response to glucose, leptin and xenin was examined. EE cages were supplemented with a house, running wheels, igloos, wood logs, maze and nesting materials. Four weeks after initiating EE protocol, mice were fasted for 8 h and received an intraperitoneal injection of glucose (2 mg/g b.w.) or saline just before the onset of the dark phase. Treatment assignments were reversed for the second injection so that each animal received both treatments with a washout period of 1 week. Mice were given food immediately after the injection and food intake was measured for 4 h after the injection at 0.5–1 h intervals. The same design was repeated using leptin (2.5 μg/g b.w.) and xenin (15 or 50 μg/g b.w.). Glucose injection caused a significant reduction of food intake in both control and EE mice. However, anorexic effect of glucose was more significant in EE group compared to the control group (main effect of treatment: P = 0.0016 for control and P < 0.0001 for EE, two-way ANOVA). Significant reductions in food intake were observed between 0.5 and 2.5 h after glucose injection in EE mice, while no significant reduction was observed thereafter. Moreover, three-way ANOVA showed a significant interaction between housing condition and treatment (P = 0.0086). In contrast, although both leptin and xenin caused a significant reduction in food intake, there was no significant interaction between housing condition and treatment. These data suggest that environmental enrichment enhances the anorectic action of glucose without altering feeding response to leptin and xenin. It is speculated that enhanced hypothalamic glucose sensing may mediate beneficial effects of environmental enrichment on metabolism.

The balance of concentration between Prokineticin 2β and Prokineticin 2 modulates the food intake by STAT3 signaling

The secreted bioactive peptide prokineticin 2 (PK2) is a potent adipokine and its central and peripheral administration reduces food intake in rodents. The pk2 gene has two splice variants, PK2 and PK2L (PK2 long form), which is cleaved into an active peptide, PK2β, that preferentially binds prokineticin receptor 1 (PKR1). We investigated the role of PK2β in the regulation of food intake. We demonstrated that intraperitoneal injection of PK2β, in contrast to PK2, did not reduce food intake in mice. Exposure of hypotalamic explants to PK2, but not PK2β, induced phosphorylation of STAT3 and ERK. We also evidenced that in adipocytes from PKR1 knock-out mice, a model of obesity, there were higher PK2β levels than PK2 inducing a decreased activation of STAT3 and ERK. Our results suggest that variations in PK2 and PK2β levels, due to modulation of pk2 gene splicing processes, affect food intake in mice.

77-OR: The Gut Peptide Neurotensin Does Not Reduce Appetite and Food Intake in Healthy Young Men

Background: Altered meal-associated secretion of gut peptides is key for the metabolic changes and weight-loss observed after Roux-en-Y gastric bypass (RYGB). Parenteral administration of the gut peptide neurotensin (NT) reduces food intake in rodents, and, like glucagon-like peptide-1 and peptide YY, the secretion of NT is markedly increased after RYGB. We therefore investigated the effect of intravenous (IV) NT on ad libitum food intake and appetite sensations. Design: Using a double-blinded, randomized placebo-controlled design, NT (2.5pmol/kg/min) or saline was infused IV in healthy young men to obtain NT concentrations similar to NT levels observed postprandially after RYGB. Four visits were performed in random order, after an acclimatization visit, to evaluate the main outcomes - ad libitum food intake and appetite sensations (visual analogue scale (VAS) questionnaires). Blood samples were collected for plasma and serum analyses (including entero-pancreatic peptides and glucose). NT or saline was infused after a basal period (t= -60 to 0 min). On two study days (n=18), an ad libitum meal was served after one hour of infusion (t= 60 min) followed by blood sampling/VAS until t= 120 min (infusion discontinued). On two other study days (n=16), a liquid mixed meal was ingested after one hour of infusion (t = 60 min) followed by blood sampling and VAS until an ad libitum meal was served at t= 240 min (infusion discontinued at t=270min). Results: Food intake was similar on the ad libitum meal (t = 60 min) days - NT (4150 (3607-4696)kJ, mean (95% confidence interval) vs. saline (3820 (3250-4405) kJ, P=0.062 (paired t-test)) and on the LMM + ad libitum meal (t= 240 min) days - NT (4320 (3698-5008)kJ vs. saline (4250 (3739-4870)kJ, P=0.80). NT infusions did not influence appetite sensations or elicit gastrointestinal side effects. Conclusions: Despite obtaining NT concentrations similar to what is observed postprandially after RYGB, we did not observe any differences in appetite sensations or food intake. Disclosure S. Veedfald: None. C. Martinussen: None. M.S. Svane: None. T. Justinussen: None. M.G. Hindsø: None. N. Hedbäck: None. C.B. Christiansen: None. N.J. Wewer Albrechtsen: Research Support; Self; Mercodia, Novo Nordisk A/S, Novo Nordisk Foundation. Speaker’s Bureau; Self; Merck Sharp &amp; Dohme Corp. K.N. Bojsen-Moller: None. B. Hartmann: None. M. Fenger: None. J.F. Rehfeld: None. S. Madsbad: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Sanofi-Aventis. Research Support; Self; Boehringer Ingelheim International GmbH, Novo Nordisk A/S. Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Novo Nordisk A/S. J.J. Holst: Advisory Panel; Self; AstraZeneca, Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Zealand Pharma A/S. Other Relationship; Spouse/Partner; Antag Therapeutics. Funding Desirée og Niels Ydes Fond; Læge Sophus og hustru Olga Friis Legat; Beckett Fonden; Hørslev Fonden; Aase og Ejnar Danielsens Fond; Fabrikant Frands Køhler Nielsen og hustrus legat; Carl og Ellen Hertz’ Legat

Food Intake is Influenced by Gastric Emptying, Motility, and Compliance

Obesity, which results from an increase in caloric intake relative to energy expenditure, is often associated with an alterations in gastric emptying. The exact relationship between gastric emptying and food intake, however, is unclear. Some reports have suggested that obesity is associated with an accelerated liquid but a delayed solid gastric emptying rate, while more recent studies have suggested that there may be no significant correlation between BMI and gastric emptying. The purpose of the present study is to test the hypothesis that food intake in rodents is influenced by a combination of gastric emptying, gastric tone and motility, and compliance.Male and female Sprague‐Dawley rats (4–8 weeks of age) were fed a control or HFD (14% or 60% kcal from fat, respectively) for 3–5 days prior to experimentation (acute HFD). Food intake and body weight were measured twice daily prior to, and throughout, HFD exposure. The 13C octanoic acid breath test was used to measure gastric emptying rates in rats repeatedly throughout exposure to the high fat diet. Miniature strain gauges were sewn onto the ventral surface of the corpus and the antrum of the stomach in anesthetized rats to allow measurement of basal gastric motility and tone. Gastric compliance was measured via a latex balloon inserted into the stomach via the pylorus in anesthetized rats. Following placement, the balloon was maximally inflated (2mL; 1min) before deflation. After 10min recovery, the balloon was then inflated in 0.2mL increments for 1 minute each, and the balloon pressure measured continuously.Acute high fat diet exposure induced a brief (24hr) period of hyperphagia before rats regulate their food intake and restore caloric balance within a 3–5 day period (74.7±4.0 kcal/day at day 1 vs. 59±3.7 kcal/day at days 3–5, P&lt;0.05, N=16), as described previously (PMID: 29368945). While gastric emptying rate was not significantly different during the hyperphagic period following high fat diet exposure (120±14.1% of baseline, P&gt;0.05, N=6), emptying was significantly delayed after 4 days HFD exposure (144±15.8% of baseline, P&gt;0.05, N=6), when caloric intake is restored to baseline levels. Neither gastric compliance (total AUC throughout distention volume range: 37±1.7 vs. 38±1.1, P&gt;0.05, N=6–8) nor basal gastric motility (104±12.2 vs. 110±16.3mg/min P&gt;0.05, N=10–13) was altered during this time period.These data suggest that i) gastric emptying rates are more closely associated with the regulation of caloric intake and energy balance than either basal gastric motility or compliance, and ii) gastric emptying may be disrupted without any observed alterations in local gastric functions. We have shown previously, that restoration of caloric balance is associated with neuroplasticity within central vagal neurocircuits (PMID: 29368945). These data suggest that dysregulation of gastric emptying may be important in the central control of food intake, even under conditions where alterations in peripheral gastric functions, including motility and compliance, are not observed.Support or Funding InformationNIH DK111667 to KNB NIH F31 118833 to CC

Salmon calcitonin distributes into the arcuate nucleus to a subset of NPY neurons in mice

The amylin receptor (AMY) and calcitonin receptor (CTR) agonists induce acute suppression of food intake in rodents by binding to receptors in the area postrema (AP) and potentially by targeting arcuate (ARC) neurons directly. Salmon calcitonin (sCT) induces more potent, longer lasting anorectic effects compared to amylin. We thus aimed to investigate whether AMY/CTR agonists target key neuronal populations in the ARC, and whether differing brain distribution patterns could mediate the observed differences in efficacy with sCT and amylin treatment. Brains were examined by whole brain 3D imaging and confocal microscopy following subcutaneous administration of fluorescently labelled peptides to mice. We found that sCT, but not amylin, internalizes into a subset of ARC NPY neurons, along with an unknown subset of ARC, AP and dorsal vagal motor nucleus cells. ARC POMC neurons were not targeted. Furthermore, amylin and sCT displayed similar distribution patterns binding to receptors in the AP, the organum vasculosum of the lamina terminalis (OVLT) and the ARC. Amylin distributed within the median eminence with only specs of sCT being present in this region, however amylin was only detectable 10 minutes after injection while sCT displayed a residence time of up to 2 hours post injection. We conclude that AMY/CTR agonists bind to receptors in a subset of ARC NPY neurons and in circumventricular organs. Furthermore, the more sustained and greater anorectic efficacy of sCT compared to rat amylin is not attributable to differences in brain distribution patterns but may more likely be explained by greater potency at both the CTR and AMY.

GPR40 full agonism exerts feeding suppression and weight loss through afferent vagal nerve.

GPR40/FFAR1 is a Gq protein-coupled receptor expressed in pancreatic β cells and enteroendocrine cells, and mediates insulin and incretin secretion to regulate feeding behavior. Several GPR40 full agonists have been reported to reduce food intake in rodents by regulating gut hormone secretion in addition to their potent glucose-lowering effects; however, detailed mechanisms of feeding suppression are still unknown. In the present study, we characterized T-3601386, a novel compound with potent full agonistic activity for GPR40, by using in vitro Ca2+ mobilization assay in Chinese hamster ovary (CHO) cells expressing FFAR1 and in vivo hormone secretion assay. We also evaluated feeding suppression and weight loss after the administration of T-3601386 and investigated the involvement of the vagal nerve in these effects. T-3601386, but not a partial agonist fasiglifam, increased intracellular Ca2+ levels in CHO cells with low FFAR1 expression, and single dosing of T-3601386 in diet-induced obese (DIO) rats elevated plasma incretin levels, suggesting full agonistic properties of T-3601386 against GPR40. Multiple doses of T-3601386, but not fasiglifam, in DIO rats showed dose-dependent weight loss accompanied by feeding suppression and durable glucagon-like peptide-1 elevation, all of which were completely abolished in Ffar1-/- mice. Immunohistochemical analysis in the nuclei of the solitary tract demonstrated that T-3601386 increased the number of c-Fos positive cells, which also disappeared in Ffar1-/- mice. Surgical vagotomy and drug-induced deafferentation counteracted the feeding suppression and weight loss induced by the administration of T-3601386. These results suggest that T-3601386 exerts incretin release and weight loss in a GPR40-dependent manner, and that afferent vagal nerves are important for the feeding suppression induced by GPR40 full agonism. Our novel findings raise the possibility that GPR40 full agonist can induce periphery-derived weight reduction, which may provide benefits such as less adverse effects in central nervous system compared to centrally-acting anti-obesity drugs.

Brain region-specific neuromedin U signalling regulates alcohol-related behaviours and food intake in rodents.

Albeit neuromedin U (NMU) attenuates alcohol‐mediated behaviours, its mechanisms of action are poorly defined. Providing that the behavioural effects of alcohol are processed within the nucleus accumbens (NAc) shell, anterior ventral tegmental area (aVTA), and laterodorsal tegmental area (LDTg), we assessed the involvement of NMU signalling in the aforementioned areas on alcohol‐mediated behaviours in rodents. We further examined the expression of NMU and NMU receptor 2 (NMUR2) in NAc and the dorsal striatum of high compared with low alcohol‐consuming rats, as this area is of importance in the maintenance of alcohol use disorder (AUD). Finally, we investigated the involvement of NAc shell, aVTA and LDTg in the consumption of chow and palatable peanut butter, to expand the link between NMU and reward‐related behaviours. We demonstrated here, that NMU into the NAc shell, but not aVTA or LDTg, blocked the ability of acute alcohol to cause locomotor stimulation and to induce memory retrieval of alcohol reward, as well as reduced peanut butter in mice. In addition, NMU into NAc shell decreased alcohol intake in rats. On a molecular level, we found increased NMU and decreased NMUR2 expression in the dorsal striatum in high compared with low alcohol‐consuming rats. Both aVTA and LDTg, rather than NAc shell, were identified as novel sites of action for NMU's anorexigenic properties in mice based on NMU's ability to selectively reduce chow intake when injected to these areas. Collectively, these data indicate that NMU signalling in different brain areas selectively modulates different behaviours.

Hypothalamic mechanism of corticotropin-releasing factor’s anorexigenic effect in Japanese quail (Coturnix japonica)

Central administration of corticotropin-releasing factor (CRF), a 41-amino acid peptide, is associated with anorexigenic effects across various species, with particularly potent reductions in food intake in rodents and chickens (Gallus gallus domesticus), a species for which the most is known. The purpose of the current study was to determine the hypothalamic mechanism of CRF-induced anorexigenic effects in 7 day-old Japanese quail (Coturnix japonica), a less-intensely-selected gallinaceous relative to the chicken that can provide more evolutionary perspective. After intracerebroventricular (ICV) injection of 2, 22, or 222 pmol of CRF, a dose-dependent decrease in food intake was observed that lasted for 3 and 24 h for the 22 and 222 pmol doses, respectively. The 2 pmol dose had no effect on food or water intake. The numbers of c-Fos immunoreactive cells were increased in the paraventricular nucleus (PVN) and lateral hypothalamic area (LHA) at 1 h post-injection in quail injected with 22 pmol of CRF. The hypothalamic mRNA abundance of proopiomelanocortin, melanocortin receptor subtype 4, CRF, and CRF receptor sub-type 2 was increased at 1 h in quail treated with 22 pmol of CRF. Behavior analyses demonstrated that CRF injection reduced feeding pecks and jumps and increased the time spent standing. In conclusion, results demonstrate that the anorexigenic effects of CRF in Japanese quail are likely influenced by the interaction between CRF and melanocortin systems and that injection of CRF results in species-specific behavioral changes.

Abstract P383: High Sodium Intake is Independently Associated with Subclinical Hypercortisolism in Hypertensive Patients

The widely accepted notion of an increase in water intake to compensate for a similar increase in salt consumption has recently been challenged by evidence of long-term renal and metabolic mechanisms favouring endogenous water accrual and body fluid preservation. A glucocorticoid-driven catabolic state is instrumental to this aim and is prevented by increased food intake in rodents. Demonstration of these mechanisms in large human populations is lacking and their relevance for cardiovascular disease is therefore unknown. We explored the association between sodium intake (estimated by 24h urine sodium excretion; USE) and 24h urinary free cortisol (UFC) in 145 patients screened for secondary causes of hypertension in a tertiary referral centre, after washout from drugs affecting the renin-angiotensin-aldosterone system (63 males, 43.3%; age, 48 [38-56] years; BMI, 27.1 [24.3-31.0] kg/m 2 ). USE was directly associated with UFC (Spearman’s rho=0.407, p&lt;0.001), as well as male gender (r=0.381, p&lt;0.001), BMI (r=0.243, p=0.006), creatinine clearance (r=0.637, p&lt;0.001) and, borderline, to plasma glucose (r=0.268, p=0.065). Importantly, UFC increased across classes of sodium intake (Low &lt; 2.3g/d, Medium 2.3-5g/d and High &gt; 5g/d) in lean and overweight groups (n=41, ANOVA p = 0.005 and n= 49, ANOVA p &lt; 0.001, respectively), but not in obese subjects (n=35; p = 0.083). Linear regression analysis showed that (square root-transformed) USE was the strongest explanatory variable for UFC after correction for age, gender, BMI, eGFR and aldosterone:renin ratio (β = 0.04, p &lt; 0.0005). A regression model that also included (Log-transformed) BMI as a surrogate of excess food intake (β = -0.51, p = 0.042), explained 23% of UFC variability in the cohort. We conclude that sodium intake, as estimated by USE, is an independent predictor of subclinical hypercortisolism in lean and overweight but possibly not in obese subjects. These data, in a population at increased cardiovascular risk, suggest a link between sodium intake and subclinical metabolic derangement, which could further add to the overall risk profile.

MEDI0382, a GLP-1/Glucagon Receptor Dual Agonist, Acutely Inhibits Food Intake in Leptin-Deficient ob/ob Mice and Leptin Receptor–Deficient fa/fa Rats

MEDI0382 is a potent glucagon-like-peptide-1 (GLP-1) and glucagon receptor dual agonist that inhibits feeding and induces weight loss in mice. To test whether MEDI0382-mediated improvements in metabolism require leptin signaling, we determined its acute effects on food intake in rodents lacking either leptin (ob/ob mice) or the leptin receptor (fa/fa rats). An acute dose response study in ob/ob mice was performed with mice dosed subcutaneously (SC) with GLP-1 receptor agonist liraglutide (30 nmol/kg), glucagon receptor agonist G1437 (30 nmol/kg), or MEDI0382 (1, 3, 10 or 30 nmol/kg). At 24 h, liraglutide and G1437 treatment reduced food intake by 50% and 16% vs. controls, respectively. MEDI0382 inhibited food intake in a dose-dependent manner, and exerted superior inhibition of food intake compared to equimolar doses of liraglutide and G1437. The fa/fa rats were also dosed once with liraglutide, G1437 (both at same doses as above), or MEDI0382 (3, 10 and 30 nmol/kg) and food intake measured. Liraglutide and G1437 treatment decreased 24 h food intake by 55% and 27% respectively and MEDI0382 dose-dependently decreased food intake (32%, 67% and 77%). Also, fa/fa rats treated with MEDI0382 had an additional reduction in food intake than equimolar doses of either liraglutide or G1437. Finally, lean C57BL/6 mice housed in the BioDaq food intake monitoring system were dosed SC once with MEDI0382 (0.3, 1, 3, 10 and 30 nmol/kg), and a dose-dependent effect on inhibition of food intake was observed. Further analysis showed MEDI0382 decreased total meal number and increased satiety ratio. In summary, MEDI0382 exerted potent anorexigenic effects in mice independent of the leptin pathway, characterized by decreased number of meals consumed and increased satiety. Disclosure V.G. Howard: Employee; Self; AstraZeneca. Stock/Shareholder; Self; Regeneron Pharmaceuticals, Inc., AstraZeneca. S. Oldham: Stock/Shareholder; Self; AstraZeneca. Employee; Self; MedImmune. A. Konkar: Employee; Self; Sanofi. Other Relationship; Self; MedImmune. J. Trevaskis: Employee; Self; MedImmune. Stock/Shareholder; Self; AstraZeneca. S. Will: Employee; Self; MedImmune. Stock/Shareholder; Self; AstraZeneca.

Acute orexigenic effect of agmatine involves interaction between central α2-adrenergic and GABAergic receptors

Agmatine and GABA have been abundantly expressed in brain nuclei involved in regulation of energy homeostasis and promoting stimulation of food intake in rodents. However, their mutual interaction, if any, in the elicitation of feeding behavior is largely remains unclear. The current study provides experimental evidence for the possible interaction of agmatine, adrenergic and GABAergic systems in stimulation of feeding in satiated rats.Satiated rats fitted with intracerebroventricular (i.c.v.) cannulae and were administered agmatine, alone or jointly with (a) GABAA receptor agonist, muscimol, diazepam or antagonist bicuculline and flumazenil, GABAA positive modulator, allopregnanolone or negative modulator of GABAA receptor, dehydroepiandrosterone (b) In view of the high affinity of agmatine for α2-adrenoceptors and the close association between α2-adrenoceptors and GABAergic system, the effect of their modulators on feeding elicited by agmatine/GABAergic agonists were also examined. I.c.v. administration of agmatine (40–80μg/rat) induces the significant orexigenic effect in satiated rats. The orexigenic effect of agmatine was potentiated by muscimol (25ng/rat, i.c.v.); diazepam (0.5mg/kg, i.p.); allopregnanolone (0.5mg/kg, s.c.) and blocked by bicuculline (1mg/kg, i.p.) and dehydroepiandrosterone (4mg/kg,s.c.). However, it remained unaffected in presence of flumazenil (25ng/rat, i.c.v.). The orexigenic effect of agmatine and GABAergic agonists was potentiated by a α2-adrenoceptors agonist, clonidine (10ng/rat, i.c.v.) and blocked by its antagonist, yohimbine (5μg/rat, i.c.v.). Yohimbine also blocked the hyperphagic effect elicited by ineffective dose combination of agmatine (5μg/rat, i.c.v.) with muscimol (25ng/rat, i.c.v.) or diazepam (0.5mg/kg, i.p.) or allopregnanolone (0.5mg/kg,s.c.). The results of the present study suggest that agmatine induced α2-adrenoceptors activation might facilitate GABAergic activity to stimulate food intake in satiated rats.

Feeding Experimentation Device (FED): Construction and Validation of an Open-source Device for Measuring Food Intake in Rodents

Feeding Experimentation Device (FED): Construction and Validation of an Open-source Device for Measuring Food Intake in Rodents

Feeding Experimentation Device (FED): Construction and Validation of an Open-source Device for Measuring Food Intake in Rodents.

Food intake measurements are essential for many research studies. Here, we provide a detailed description of a novel solution for measuring food intake in mice: the Feeding Experimentation Device (FED). FED is an open-source system that was designed to facilitate flexibility in food intake studies. Due to its compact and battery powered design, FED can be placed within standard home cages or other experimental equipment. Food intake measurements can also be synchronized with other equipment in real-time via FED's transistor-transistor logic (TTL) digital output, or in post-acquisition processing as FED timestamps every event with a real-time clock. When in use, a food pellet sits within FED's food well where it is monitored via an infrared beam. When the pellet is removed by the mouse, FED logs the timestamp onto its internal secure digital (SD) card and dispenses another pellet. FED can run for up to 5 days before it is necessary to charge the battery and refill the pellet hopper, minimizing human interference in data collection. Assembly of FED requires minimal engineering background, and off-the-shelf materials and electronics were prioritized in its construction. We also provide scripts for analysis of food intake and meal patterns. Finally, FED is open-source and all design and construction files are online, to facilitate modifications and improvements by other researchers.