Differential changes in appetite hormones post-prandially based on menstrual cycle phase and oral contraceptive use: A preliminary study

This was a preliminary study that examined whether appetite regulation is altered during the menstrual cycle or with oral contraceptives. Ten naturally cycling females (NON-USERS) and nine tri-phasic oral contraceptive using females (USERS) completed experimental sessions during each menstrual phase (follicular phase: FP; ovulatory phase: OP; luteal phase: LP). Appetite perceptions and blood samples were obtained fasted, 30, 60, and 90 min post-prandial to measure acylated ghrelin, active glucagon-like peptide-1 (GLP-1), and total peptide tyrosine tyrosine (PYY). Changes were considered important if p < 0.100 and the effect size was ≥medium. There appeared to be a three-way (group x phase x time) interaction for acylated ghrelin where concentrations appeared to be greater in USERS versus NON-USERS during the OP 90-min post-prandial and during the LP fasted, and 90-min post-prandial. In USERS, ghrelin appeared to be greater 90-min post-prandial in the OP versus the FP with no other apparent differences between phases. There were no apparent differences between phases in NON-USERS. There appeared to be a three-way interaction for PYY where concentrations appeared to be greater in USERS during the FP 60-min post-prandial and during the OP 30-min post-prandial. In USERS PYY appeared to be greater 60-min post-prandial during the OP versus the LP with no other apparent differences. There were no apparent differences between phases in NON-USERS. There appeared to be no effect of group or phase on GLP-1, or appetite perceptions. These data demonstrate small effects of menstrual cycle phase and oral contraceptive use on the acylated ghrelin and total PYY response to a standardized meal, with no effects on active GLP-1 or perceived appetite, though more work with a large sample size is necessary.

NUCB2/nesfatin-1 in the acute stress response of obese women with high and low anxiety

NUCB2/nesfatin-1 is an anorexigenic peptide hormone first known for its effects on energy homeostasis. More recently, a growing evidence suggests a role of NUCB2/nesfatin-1 in emotion regulation, particularly in the modulation of anxiety, depression and emotional stress response. Since stress-related mood disorders are often comorbid with obesity, we investigated the effect of acute psychosocial stress on circulating NUCB2/nesfatin-1 in obese women and normal-weight controls and its association with symptoms of anxiety. Forty women, 20 obese and 20 normal-weight controls, (aged between 27 and 46 years) were exposed to the Trier Social Stress Test (TSST). We assessed changes of plasma NUCB2/nesfatin-1, salivary cortisol, heart rate and subjective emotional state. Symptoms of anxiety (GAD-7), depressiveness (PHQ-9), perceived stress (PSQ-20), disordered eating (EDE-Q, EDI-2) and health-related quality of life (SF-8) were measured psychometrically. Obese women were further subdivided in a high and low anxiety group. Women with obesity displayed higher psychopathology compared to normal-weight controls. The TSST induced a biological and psychological stress response in both groups (p < 0.001). In normal-weight controls NUCB2/nesfatin-1 increased in response to stress (p = 0.011) and decreased during recovery (p < 0.050), while in obese women only the decrease during recovery was significant (p = 0.002). Obese women with high anxiety displayed higher NUCB2/nesfatin-1 levels than those in the low anxiety group (TSST: +34 %, p = 0.008; control condition: +52 %, p = 0.013). Our data substantiate the involvement of NUCB2/nesfatin-1 in the modulation of stress and anxiety. It remains unclear whether the attenuated stress response in obese subjects is due to metabolic changes or mental comorbidity.

The exercise-induced suppression of acylated ghrelin is blunted in the luteal phase of the menstrual cycle compared to the follicular phase following vigorous-intensity exercise

Limited work examining woman's appetite-regulatory response to exercise has been focused on the follicular phase (FP) of the menstrual cycle. This is an important limitation as estradiol (E₂) and progesterone (P₄) fluctuate across phases with greater concentrations in the luteal phase (LP).

OBJECTIVE

To examine the appetite-regulatory response to vigorous-intensity continuous exercise (VICT) in the FP and LP.

METHODS

Twelve women completed 30 min of VICT at 80% V˙O_2max in the FP and LP. E₂, P₄, acylated ghrelin, active peptide tyrosine-tyrosine (PYY), active glucagon-like peptide-1 (GLP-1), and appetite perceptions were measured pre-exercise, 0-, 30-, and 90-min post-exercise. Energy intake was recorded for a 2-day period (day before and of each session). A series of two-way repeated measure ANOVA were used to compare all dependent variables.

RESULTS

Pre-exercise E₂ (P = 0.005, d = 1.00) and P₄ (P < 0.001, d = 1.41) concentrations were greater in the LP than the FP and exercise increased both at 0- and 30-min post-exercise (E₂: P < 0.009; P₄: P < 0.001, d = 0.63). Acylated ghrelin was lower in the FP versus LP at pre-exercise as well as 0-min (P = 0.006, d = 0.97) and 90-min (P = 0.029, d = 0.72) post-exercise. There were no differences of menstrual phase on PYY (P = 0.359, η_p² = 0.092), GLP-1 (P = 0.226, η_p² = 0.130), or overall appetite (P = 0.514, η_p² = 0.066). Energy intake was greater on the day of in the LP versus the FP (P = 0.003, d = 1.2).

CONCLUSION

Acylated ghrelin was lower in the FP compared to the LP and though there were no differences in anorexigenic hormones or subjective appetite, energy intake was greater on the day of the session in the LP suggesting important differences across the menstrual cycle where greater concentrations of ovarian hormones in the LP may blunt the exercise response.

Relationship Between Appetite-Related Peptides and Frailty in Older Adults

BACKGROUND

Frailty, is a geriatric syndrome that reduces the resistance to stress situations caused by activities of daily living and increases morbidity and mortality. We hypothesized that a decrease in orexigenic peptides or an increase in anorexigenic peptides might be associated with frailty. We aimed to investigate the relationship between frailty and six appetite-related peptides: ghrelin, neuropeptide Y (NPY), agouti-related peptide (AgRP), cocaine-amphetamine-associated peptide (CART), peptide YY, and alpha MSH (α-MSH).

METHODS

This cross-sectional study was conducted on 85 older adults who visited the outpatient clinic. All patients underwent comprehensive geriatric assessment. Frailty status was assessed using the Fried frailty index. Plasma levels of six appetite-related peptides were studied.

RESULTS

The mean age was 73.7 ± 5.4 years, 27 (31.8%) of the patients were male, and 32 of the patients (37.6%) were frail. While plasma levels of ghrelin, NPY and AgRP were significantly lower in frail patients, CART and α-MSH levels were higher compared to non-frail patients (p < .05 for all). Peptide YY was found to be higher in the frail group, however, the difference did not reach statistical significance (p = .052). In multivariate logistic regression analysis, the ghrelin, AgRP, CART, and α-MSH levels were independent predictors of frailty. Moreover, a weak correlation was found between all peptides(except NPY) and handgrip strength and Lawton-Brody score.

CONCLUSION

Ghrelin, AgRP, CART, and α-MSH levels were found to be independent predictors of frailty. Our results suggest that appetite-related peptides might be playing roles in the pathogenesis of frailty. Further larger prospective studies are needed to test this hypothesis.

Ferulic acid, a phytochemical with transient anorexigenic effects in birds

Ferulic acid (FA) is a phenolic acid found within the plant cell wall that has physiological benefits as an antioxidant. Although metabolic benefits of FA supplementation are described, lacking are reports of effects on appetite regulation. Thus, our objective was to determine if FA affects food or water intake, using chicks as a model. At 4 days post-hatch, broiler chicks were intraperitoneally injected with 0 (vehicle), 12.5, 25, or 50 mg/kg of FA. Chicks treated with 50 mg/kg of FA consumed 70% less food than controls at 30 min post-injection, and the effect dissipated thereafter. Water intake was not affected at any time. In a behavior analysis, FA-treated chicks defecated fewer times than vehicle-injected chicks, while other behaviors were not affected. There was an increase in c-Fos immunoreactivity within the hypothalamic arcuate nucleus (ARC) of FA-treated chicks, and no differences were detected in other nuclei. mRNA abundance was measured in the whole hypothalamus and the ARC. There was decreased hypothalamic galanin, ghrelin, melanocortin receptor 3, and pro-opiomelanocortin (POMC) mRNA in FA-treated chicks. Within the ARC, there was an increase in c-Fos mRNA and a decrease in POMC mRNA in response to FA. It is likely that the mechanism responsible for mediating FA's transient effects on food intake originates within the ARC, possibly involving POMC. A greater understanding of the short-term, mild appetite-suppressive effects of FA may have applications to treating eating disorders and modulating food intake in animal models of obesity.

The anorexigenic effect of vasoactive intestinal polypeptide in Japanese quail is associated with molecular changes in the arcuate and dorsomedial hypothalamic nuclei

Vasoactive intestinal polypeptide (VIP) is involved in gastric smooth muscle relaxation, vasodilation, and gastric secretions. It is also associated with appetite regulation, eliciting an anorexigenic response in mammals, birds, and fish; however, the molecular mechanism mediating this response is not well understood. The aim of the present study was thus to investigate hypothalamic mechanisms mediating VIP-induced satiety in 7-d old Japanese quail. In experiment 1, chicks that received intracerebroventricular (ICV) injection of VIP had reduced food intake for up to 180 min after injection and reduced water intake for 90 min. In experiment 2, VIP-treated chicks that were food restricted did not reduce water intake. In experiment 3, there was increased c-Fos immunoreactivity in the arcuate (ARC) and dorsomedial (DMN) nuclei of the hypothalamus in VIP-injected quail. In experiment 4, ICV VIP was associated with decreased neuropeptide Y mRNA in the ARC and DMN and an increase in corticotropin releasing factor mRNA in the DMN. In experiment 5, VIP-treated chicks displayed fewer feed pecks and locomotor behaviors. These results demonstrate that central VIP causes anorexigenic effects that are likely associated with reductions in orexigenic tone involving the ARC and DMN.

NUCB2/nesfatin-1 - Inhibitory effects on food intake, body weight and metabolism

Since its discovery in 2006 by Oh-I and colleagues, NUCB2/nesfatin-1 encoded by nucleobindin-2 (NUCB2) has drawn sustained attention as reflected in over 500 publications. Among those, more than half focused on the alterations of food intake, body weight and metabolism (glucose, fat) induced by nesfatin-1 and/or NUCB2/nesfatin-1. In the current review we discuss the existing literature focusing on NUCB2/nesfatin-1's influence on food intake, body weight and glucose as well as fat metabolism and highlight gaps in knowledge.

Appetite regulating genes may contribute to herbivory versus carnivory trophic divergence in haplochromine cichlids

Feeding is a complex behaviour comprised of satiety control, foraging, ingestion and subsequent digestion. Cichlids from the East African Great Lakes are renowned for their diverse trophic specializations, largely predicated on highly variable jaw morphologies. Thus, most research has focused on dissecting the genetic, morphological and regulatory basis of jaw and teeth development in these species. Here for the first time we explore another aspect of feeding, the regulation of appetite related genes that are expressed in the brain and control satiety in cichlid fishes. Using qPCR analysis, we first validate stably expressed reference genes in the brain of six haplochromine cichlid species at the end of larval development prior to foraging. We next evaluate the expression of 16 appetite related genes in herbivorous and carnivorous species from the parallel radiations of Lake Tanganyika, Malawi and Victoria. Interestingly, we find increased expression of two appetite-regulating genes (anorexigenic genes), cart and npy2r, in the brain of carnivorous species in all the three lakes. This supports the notion that appetite gene regulation might play a part in determining trophic niche specialization in divergent cichlid species, already prior to exposure to different diets. Our study contributes to the limited body of knowledge on the neurological circuitry that controls feeding transitions and adaptations in cichlids and other teleosts.

Methyleugenol counteracts anorexigenic signals in association with GABAergic inhibition in the central amygdala

Feeding can be inhibited by satiety, sickness, or food unpalatability. The central nucleus of the amygdala (CeA) has been considered the key region for processing multiple anorexigenic signals, although the detailed cellular and molecular mechanisms remain largely unclear. Here we identify that methyleugenol (ME), a novel agonist of A type ionotropic γ-aminobutyric acid receptors (GABA_ARs), significantly counteracts the anorexigenic effects caused by satiety or sickness in association with GABAergic inhibition in the CeA. Electrophysiologically, ME enhanced GABAergic transmission and repressed neuronal excitability of the CeA. Behaviorally, ME increased feeding but not affect locomotor activity and basal anxiety in naïve mice. Notably, both systemic and CeA-specific delivery of ME significantly rescued satiety- or sickness-induced inhibition of feeding. The effects of ME were mainly dependent on the GABA_ARs in the CeA. Indeed, viral-mediated, the CeA region-specific genetic knockdown of the γ2 subunit of GABA_ARs largely abolished the above pharmacological effects, while its re-expression in a subpopulation of GABAergic neurons in the CeA, that produce protein kinase C-δ (PKC-δ), recovered the effects of ME on anorexigenic signals. Taken together, these results reveal a novel molecular mechanism for counter-anorexigenic signals dependent on GABAergic inhibition in the CeA, suggesting the possibility of ME as a leading compound for anorexia treatment.

Alpha-melanocyte stimulating hormone-induced anorexia in Japanese quail (Coturnix japonica) likely involves the ventromedial hypothalamus and paraventricular nucleus of the hypothalamus

Alpha-melanocyte stimulating hormone (α-MSH) reduces food intake in birds and mammals. The objective of this experiment was to determine effects of α-MSH on food and water intake, and hypothalamic c-Fos immunoreactivity and appetite-associated factor mRNA in Japanese quail (Coturnix japonica), a species that has not undergone the same artificial selection for growth-related traits as the chicken. At 7days post-hatch, 3-h-fasted quail were intracerebroventricularly (ICV) injected into the lateral ventricle with 0 (vehicle), 0.5, 5, or 50pmol of α-MSH and food and water intake were recorded at 30min intervals for 180min. In the second and third experiment, quail were injected with 50pmol α-MSH and hypothalami were collected at 1h to determine c-Fos immunoreactivity and mRNA abundance, respectively. At 30min, quail injected with 5 or 50pmol of α-MSH ate and drank less than vehicle-injected quail. Quail injected with 50pmol ate less for the entire duration of the experiment and drank less than vehicle-injected quail for 120min post-injection. Hypothalamic expression of agouti-related peptide and DOPA decarboxylase were greater in vehicle- than α-MSH-injected quail, whereas melanocortin receptor 4 (MC4R) mRNA was greater in α-MSH- than vehicle-injected birds. Alpha-MSH injection was associated with more c-Fos immunoreactive cells in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN) of the hypothalamus. Results suggest that the anorexigenic effect of α-MSH is conserved among avians and that effects in quail are associated with the VMH and PVN and involve MC4R.

LPLRFamide exerts short-term anorexigenic effects that coincide with magnocellular division of the hypothalamic paraventricular nucleus activation

LPLRFamide is a member of the RFamide peptide family that elicits an anorexigenic effect when centrally injected in chicks although the mechanism mediating this response is poorly understood. Therefore, the purpose of this experiment was to elucidate the hypothalamic mechanism of short-term anorexia after central administration of LPLRFamide in chicks. In Experiment 1 chicks centrally injected with LPLRFamide decreased food intake at 15min but not 30min following administration compared to vehicle-injected chicks. For Experiment 2, c-Fos immunoreactivity was quantified in several appetite-associated hypothalamic nuclei and in LPLRF-injected chicks, compared to vehicle-injected chicks, there was an increase in the number of reactive cells in the magnocellular division of the paraventricular nucleus. Lastly in Experiment 3, real time-PCR was performed and hypothalamic proopiomelanocortin (POMC) mRNA abundance was increased in LPRLFamide-injected chicks compared to vehicle-injected chicks. Thus, following central injection of LPLRFamide there is activation of the paraventricular nucleus of the hypothalamus and increased expression of hypothalamic POMC mRNA in chicks.

Sex differences in the response of total PYY and GLP-1 to moderate-intensity continuous and sprint interval cycling exercise

BACKGROUND

Exercise interventions are often less effective at improving body composition for females than males, potentially due to post-exercise hormonal responses that increase energy intake in females. Recently, sprint interval training was shown to effectively reduce body fat in females despite being relatively low during exercise energy expenditure.

PURPOSE

To determine whether any sex difference in total PYY, GLP-1 or perceived hunger exists following moderate-intensity continuous exercise (MICT) and sprint interval exercise (SIT) METHODS: Twenty-one active participants (11 females) participated in three sessions in a randomized crossover design: (1) MICT, 30-min cycling at 65% VO_2max; (2) SIT, 6 × 30 s "all-out" sprints with 4-min recovery periods; (3) control (CTRL; no exercise). Blood samples were collected pre-exercise, immediately and 90 min post-exercise for the measurement of total PYY and GLP-1. Subjective perceptions of hunger were assessed using a visual analogue scale pre-breakfast and before all blood samples.

RESULTS

Concentrations of total PYY and GLP-1 were greater during MICT (P = 0.05) and SIT (P = 0.005) compared to CTRL. Total PYY increased more immediately post-exercise in males than females (P = 0.030). GLP-1 only increased in females following MICT (P = 0.034) and SIT (P = 0.024) compared to CTRL. Perceived hunger was lower immediately post-MICT (P = 0.016) and SIT (P = 0.006) compared to CTRL.

CONCLUSIONS

These results suggest that total PYY and GLP-1 respond differently to exercise in males and females over 90 min following various exercise intensities. The observed post-exercise hormonal response would not be expected to create a compensatory increase in energy intake in females.

Total PYY and GLP-1 responses to submaximal continuous and supramaximal sprint interval cycling in men

Exercise-induced changes in appetite-regulating hormones may be intensity-dependent, however a clear dose-response relationship has not been established. The purpose of this study was to examine changes in anorexigenic markers (total PYY and GLP-1) in response to rest or exercise at submaximal and supramaximal intensities. Ten active males completed four experimental sessions in randomized order: 1) Moderate intensity continuous training (MICT; 30 min cycling at 65% VO_2max); 2) High intensity continuous training (HICT; 30 min cycling at 85% VO_2max); 3) Sprint interval training (SIT; 6 × 30 s "all-out" cycling bouts with 4 min recovery periods); 4) Control (CTRL; no exercise). Blood samples were obtained immediately pre- and post-exercise, as well as 90-min post-exercise for the measurement of total PYY and GLP-1. Subjective hunger was assessed using a visual analog scale pre-breakfast and at the three blood sampling time-points. Total PYY concentrations increased immediately post-exercise following both HICT (P = 0.006) and SIT (P < 0.001) versus CTRL, while SIT was also greater (P = 0.005) compared to MICT. Total GLP-1 concentrations changed similarly across time-points (P < 0.001), with no differences between sessions (P = 0.280). Perceptions of hunger also changed similarly across time-points (P < 0.001) with no differences between trials (P = 0.085). These findings suggest that total PYY increases only after high-intensity exercise and exhibits a greater responsiveness to SIT compared to moderate-intensity exercise. Compensatory increases in hunger do not seem to occur at any exercise intensity. These findings support a dose-response relationship between exercise intensity and total PYY, though the effects on total GLP-1 and hunger perceptions seem unclear.

Cocaine- and amphetamine-regulated transcript: a novel regulator of energy homeostasis expressed in a subpopulation of pancreatic islet cells

Type 2 diabetes is characterised by chronic hyperglycaemia and its incidence is highly increased by exaggerated food consumption. It results from a lack of insulin action/production, but growing evidence suggests that it might also involve hyperglucagonaemia and impaired control of glucose homeostasis by the brain. In recent years, the cocaine and amphetamine-regulated transcript (CART) peptides have generated a lot of interest in the battle against obesity because, via the brain, they exert anorexic effects and they increase energy expenditure. They are also localised, outside the brain, in discrete regions of the body and play a hormonal role in controlling various functions. In this issue of Diabetologia, the Wierup group (doi: 10.1007/s00125-016-4020-6 ) shows that CART peptides are expressed heterogeneously in islet cells of various species, including humans, and that their expression is upregulated in diabetes. The authors also shine a spotlight on some interesting effects of CART peptides on islet function, including stimulation of insulin secretion and inhibition of glucagon release. CART peptides would thus be at the centre of a cooperation between the brain and the endocrine pancreas to control glucose homeostasis. Although the mechanisms of action of CART peptides remain enigmatic because no specific receptor for these peptides has so far been discovered, their potential therapeutic use is evident and represents a new challenge for future research.

Effect of short and long-term treatment with antipsychotics on orexigenic/anorexigenic neuropeptides expression in the rat hypothalamus

Among numerous side effects of antipsychotic drugs (neuroleptics), one of the leading problems is a significant weight gain caused by disturbances in energy homeostasis. The hypothalamus is considered an important target for neuroleptics and contains some neuronal circuits responsible for food intake regulation, so we decided to study which hypothalamic signaling pathways connected with energy balance control are modified by antipsychotic drugs of different generations. We created an expression profile of different neuropeptides after single-dose and chronic neuroleptic administration. Experiments were carried out on adult male Sprague-Dawley rats injected intraperitoneally for 1 day or for 28 days by three neuroleptics: olanzapine, chlorpromazine and haloperidol. Hypothalami were isolated in order to perform PCR reactions and also whole brains were sliced for immunohistochemical analysis. We assessed the expression of orexigenic/anorexigenic neuropeptides and their receptors--neuropeptide Y (NPY), NPY receptor type 1 (Y1R), preproorexin (PPOX), orexin A, orexin receptor type 1 (OX1R) and 2 (OX2R), nucleobindin 2 (NUCB2), nesfatin-1, proopiomelanocortin (POMC), alpha-melanotropin (α-MSH) and melanocortin receptor type 4 (MC4R)--both on the mRNA and protein levels. We have shown that antipsychotics of different generations administered chronically have the ability to upregulate PPOX, orexin A and Y1R expression with little or no effect on orexigenic receptors (OX1R, OX2R) and NPY. Interestingly, antipsychotics also increased the level of some anorexigenic factors (POMC, α-MSH and MC4R), but at the same time strongly downregulated NUCB2 and nesfatin-1 signaling--a newly discovered neuropeptide known as a food-intake inhibiting factor. Our results may contribute to a better understanding of mechanisms responsible for antipsychotics' side effects. They also underline the complex nature of interactions between classical monoamine receptors and hypothalamic peptidergic pathways, which has potential clinical applications.