Epigenetic modifiers identified as regulators of food intake in a unique hypophagic chicken model.

DNA methylation is an epigenetic modification that influences gene transcription; however, the effects of methylation-influencing chemicals on appetite are unknown. We evaluated the effects of single administration of a methyl donor, S-Adenosylmethionine (SAM), or methylation inhibitor, 5-Azacytidine (AZA), on immediate and later-age food intake in an anorexic chick model. The doses of intracerebroventricularly-injected SAM were 0 (vehicle), 0.1, 1, and 10 µg, and of AZA were 0 (vehicle), 1, 5, and 25 µg. When injected on day 5 posthatch, there was no effect of SAM on food intake in either fed or fasted chicks, whereas AZA increased food consumption in the fasted state but decreased it in fed chicks. We then performed a single injection (same doses) at hatch and measured food intake on day 5 in response to neuropeptide Y (NPY; 0.2 µg) injection. Irrespective of NPY, chicks injected with 1 µg of SAM ate more than others on day 5. In contrast, chicks injected with AZA (5 and 25 µg doses) consumed less on day 5. In conclusion, we identified DNA methylation-regulating chemicals as regulators of food intake. AZA but not SAM affected food intake in the short-term, feeding state dependently. Later, both chemicals injected on the day of hatch were associated with food intake changes at a later age, suggesting that feeding pathways might be altered through changes in methylation.

The anorexigenic effect of adrenomedullin in Japanese quail (Coturnix japonica) involves increased proopiomelanocortin and cocaine- and amphetamine-regulated transcript mRNAs in the arcuate nucleus of the hypothalamus.

Central administration of adrenomedullin (AM), a 52-amino acid peptide, is associated with anorexigenic effects in some species, including rodents and chickens. However, the associated hypothalamic mechanisms remain unclear and it is unknown if this peptide exerts satiety-inducing effects in other avian species. The objective of this study was thus to investigate AM-induced anorexigenic effects in 7-day-old Japanese quail (Coturnix japonica). After intracerebroventricular injection of 0.3, 1.0, or 3.0 nmol of AM, quail injected with 3.0 nmol of AM ate and drank less than vehicle-injected quail at 180 min after injection. Except for the 1.0 nmol dose of AM exerting an anorexigenic effect at 90 min after injection, no other inhibitory effects on food or water intake were observed. At 60 min after injection, the AM-injected quail had more c-Fos immunoreactive cells in the arcuate nucleus (ARC) than vehicle-injected birds. In the ARC, AM injection was associated with increased proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) mRNAs. In conclusion, the results suggest that the anorexigenic effect of AM is possibly influenced by the synergistic effect of POMC and CART in the ARC.

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.

Effect of zymosan on feed passage in the digestive tract in chicks.

1. The purpose of the present study was to examine whether zymosan, which is a component of fungi, affects feed passage through the digestive tract in chicks (Gallus gallus).2. Intraperitoneal (IP) injection of 2.5 mg zymosan significantly reduced the crop-emptying rate and this effect was similar to that of 100 µg lipopolysaccharide (LPS). Zymosan affected phenol red transit from the proventriculus.3. Zymosan significantly affected the gene expression of interleukin-1ß (IL-1ß), IL-6, IL-8 and histidine decarboxylase in various regions of the digestive tract.4. The present study suggested that zymosan retarded feed passage through the digestive tract in chick and interleukins and histamine may be participating in this process.

Behavioral and physiological responses to intraperitoneal injection of zymosan in chicks.

Zymosan is a cell wall component of the yeast Saccharomyces cerevisiae and produces severe inflammatory responses in mammals. When zymosan is peripherally injected in mammals, it induces several behavioral and physiological changes including anorexia and hyperthermia. However, to our knowledge, behavioral and physiological responses to zymosan have not yet been clarified in birds. Therefore, the purpose of the present study was to determine if intraperitoneal injection of zymosan affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and splenic gene expression of cytokines in chicks (Gallus gallus). Intraperitoneal injection of zymosan (2.5 mg) significantly decreased food intake, voluntary activity, and plasma glucose concentration, and increased plasma CORT concentration. The injection of 0.5 mg zymosan significantly increased cloacal temperature, while 2.5 mg zymosan had a tendency to increase it. Finally, 2.5 mg zymosan significantly increased the splenic gene expression of interleukin-1ß (IL-1ß), IL-6, IL-8, interferon-γ, and tumor necrosis factor-like cytokine 1A. The present results suggest that zymosan would be one of components which induces nonspecific symptoms including anorexia, hypoactivity, hyperthermia, and stress responses, under fungus infection in chicks.

Prolactin-releasing peptide increases food intake and affects hypothalamic physiology in Japanese quail (Coturnix japonica).

Prolactin-releasing peptide (PrRP) increases food intake in birds, whereas it is a potent satiety factor in rodents and fish. The aim of this study was to determine the effects of central injection of PrRP on feeding behaviors and hypothalamic physiology in juvenile Japanese quail (Coturnix japonica). Intracerebroventricular injection of 1,692 pmol of PrRP increased food intake for the first 90 min after injection but did not affect water intake. Quail treated with PrRP displayed more food and drink pecks, less time standing but more perching, and decreased defecations. Prolactin-releasing peptide-injected quail had increased c-Fos immunoreactivity in the dorsomedial nucleus (DMN) and arcuate nucleus (ARC) of the hypothalamus. Hypothalamic neuropeptide Y receptor subtypes 2 and 5 and melanocortin receptor 4 mRNAs were greater in PrRP- than vehicle-injected quail. In the DMN, there was less corticotropin-releasing factor (CRF) mRNA and in the ARC, more CRF mRNA in PrRP- than vehicle-injected chicks. Thus, PrRP increases food intake in quail, which is associated with changes in hypothalamic CRF and neuropeptide Y receptor gene expression and c-Fos-immunolabeled cells in the ARC and DMN.

Effects of toll-like receptor-7 agonists on feeding behaviour, voluntary activity, cloacal temperature and crop emptying in chicks.

1. The purpose of the present study was to determine if an intraperitoneal injection of two toll-like receptor-7 (TLR7) agonists, imiquimod and resiquimod, affect feed intake, voluntary activity, cloacal temperature, crop-emptying rate, plasma corticosterone (CORT) and glucose concentrations, and splenic gene expression of cytokines in chicks (Gallus gallus). 2. Although intraperitoneal injection of 100 µg imiquimod significantly increased splenic gene expression of interleukin-1ß (IL-1ß), IL-6, IL-8, and interferon-γ (IFN-γ), it did not affect feed intake, voluntary activity, cloacal temperature, crop-emptying rate or plasma constituents. 3. Intraperitoneal injection of 100 µg resiquimod significantly decreased feed intake, voluntary activity, cloacal temperature, crop-emptying rate and increased plasma corticosterone concentrations. 4. Intraperitoneal injection of resiquimod significantly increased splenic gene expression of IL-1ß, IL-6, IL-8, IFN-γ, and tumour necrosis factor-like cytokine 1A. 5. The results showed that activation of TLR7 is associated with anorexia, hypoactivity, hypothermia, disturbance of feed passage in the digestive tract and the response to stress in chicks.

Physiological responses to central and peripheral injection of polyinosinic-polycytidylic acid in chicks.

1. The purpose of the present study was to determine if intracerebroventricular (ICV) and intraperitoneal (IP) injection of polyinosinic-polycytidylic acid (poly I:C), a viral mimetic that binds to toll-like receptor-3 (TLR3), affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and crop emptying rate in chicks (Gallus gallus). 2. Both ICV and IP injection of poly I:C significantly decreased food intake. 3. IP but not ICV injection of poly I:C significantly suppressed voluntary activity, whereas ICV injection decreased time spent sitting. Both ICV and IP injection of poly I:C significantly increased plasma CORT and glucose concentration. Neither ICV nor IP injection of poly I:C significantly affected cloacal temperature. 4. In addition, ICV injection of poly I:C significantly reduced crop emptying rate, whereas IP injection had no effect. 5. These results suggested that central TLR3 is related to anorexia, stress response and retardation of crop emptying while peripheral TLR3 is related to anorexia, change in behaviour and stress responses during viral infection in chicks.

Effect of l-tryptophan and its metabolites on food passage from the crop in chicks.

l-tryptophan (l-Trp), an essential amino acid, is well known as a precursor of 5-hydroxytryptamine (5-HT) and melatonin. In mammals, l-Trp itself has been reported to suppress gastric emptying in mammals. In addition, 5-HT and melatonin are found in the gastrointestinal tract and affect food passage from the digestive tract in mammals. While the function of these factors in mammals is documented, there is little knowledge on their function in the digestive tract of birds. Therefore, the purpose of the present study was to determine if l-Trp and its metabolites affect the crop emptying rate in chicks (Gallus gallus). We also investigated the effects of kynurenic acid (KYNA) and quinolinic acid (QA), which are metabolites of the kynurenine pathway for l-Trp. Oral administration of l-Trp significantly reduced the crop emptying rate in chicks. Among the metabolites, intraperitoneal injection of 5-HT and melatonin significantly reduced the crop emptying rate, whereas KYNA and QA had no effect. The present study suggests that l-Trp, 5-HT, and melatonin inhibit the movement of food in the digestive tract and thereby affect the utilization of nutrients in the diet of chicks.

Stress-induced suppression of neuropeptide Y-induced hunger in anorexic chicks involves corticotrophin-releasing factor signalling and the paraventricular nucleus of the hypothalamus.

The Virginia lines of chickens have been selected for low (LWS) or high (HWS) juvenile body weight and have different severities of anorexia and obesity, respectively. The LWS that are exposed to stressors at hatch are refractory to neuropeptide Y (NPY)-induced food intake and the objective of the present study was to determine the underlying mechanisms. Chicks were exposed to a stressor (-20°C for 6 minutes and 22°C and delayed access to food for 24 hours) after hatching and the hypothalamic nuclei, including the lateral hypothalamus (LH), paraventricular nucleus (PVN), ventromedial hypothalamus (VMH) and arcuate nucleus (ARC), were collected 5 days later. In LWS but not HWS, stress exposure up-regulated corticotrophin-releasing factor (CRF), CRF receptor subtypes 1 and 2 (CRFR1 and CRFR2, respectively), melanocortin receptor 4 and urocortin 3 in the PVN, as well as CRFR2 mRNA in the VMH and ARC. In LWS, stress exposure was also associated with greater NPY and NPY receptor subtype 5 mRNA in the ARC and PVN, respectively, as well as decreased agouti-related peptide mRNA in the ARC. In HWS, stress exposure was associated with increased CRFR1 and decreased cocaine- and amphetamine-regulated transcript in the ARC and PVN, respectively. Refractoriness of the food intake response to NPY in LWS may thus result from the over-riding anorexigenic tone in the PVN associated with CRF signalling. Indeed, the orexigenic effect of NPY was restored when LWS were injected with a CRF receptor antagonist, astressin, before stress exposure. The results of the present study provide insights into the molecular basis of eating disorders and suggest that CRF signalling in the PVN may exacerbate the anorexic phenotype in the presence of environmental stressors.

Differential expression of appetite-regulating genes in avian models of anorexia and obesity.

Chickens from lines that have been selected for low (LWS) or high (HWS) juvenile body weight for more than 57 generations provide a unique model by which to research appetite regulation. The LWS display different severities of anorexia, whereas all HWS become obese. In the present study, we measured mRNA abundance of various factors in appetite-associated nuclei in the hypothalamus. The lateral hypothalamus (LHA), paraventricular nucleus (PVN), ventromedial hypothalamus (VMH), dorsomedial nucleus (DMN) and arcuate nucleus (ARC) were collected from 5 day-old chicks that were fasted for 180 minutes or provided with continuous access to food. Fasting increased neuropeptide Y receptor subtype 1 (NPYR1) mRNA in the LHA and c-Fos in the VMH, at the same time as decreasing c-Fos in the LHA, neuropeptide Y receptor subtype 5 and ghrelin in the PVN, and neuropeptide Y receptor subtype 2 in the ARC. Fasting increased melanocortin receptor subtype 3 (MC3R) expression in the DMN and NPY in the ARC of LWS but not HWS chicks. Expression of NPY was greater in LWS than HWS in the DMN. neuropeptide Y receptor subtype 5 mRNA was greater in LWS than HWS in the LHA, PVN and ARC. Expression of orexin was greater in LWS than HWS in the LHA. There was greater expression of NPYR1, melanocortin receptor subtype 4 and cocaine- and amphetamine-regulated transcript in HWS than LWS and mesotocin in LWS than HWS in the PVN. In the ARC, agouti-related peptide and MC3R were greater in LWS than HWS and, in the VMH, orexin receptor 2 and leptin receptor were greater in LWS than HWS. Greater mesotocin in the PVN, orexin in the LHA and ORXR2 in the VMH of LWS may contribute to their increased sympathetic tone and anorexic phenotype. The results of the present study also suggest that an increased hypothalamic anorexigenic tone in the LWS over-rides orexigenic factors such as NPY and AgRP that were more highly expressed in LWS than HWS in several nuclei.

Possible role of central interleukins on the anorexigenic effect of lipopolysaccharide in chicks.

1. The purpose of the present study was to determine if central interleukin-1ß (IL1ß), interleukin-6 (IL6) and interleukin-8 (IL8) affect feeding behaviour in chicks (Gallus gallus) and examine if central interleukins are related to the lipopolysaccharide (LPS)-induced anorexia. 2. Intra-abdominal (IA) injection of LPS significantly suppressed feeding behaviour and significantly increased mRNA expression of IL1ß and IL8 in the diencephalon when compared to the control group, while IL6 tended to be increased. 3. Intracerebroventricular (ICV) injection of 200 ng IL1ß significantly decreased food intake at 60 min after the injection while IL6 and IL8 had no effect. 4. IA injection of these ILs (200 ng) had no effect on food intake in chicks. 5. ICV injection of 200 ng IL1ß did not affect water intake and plasma corticosterone concentration, suggesting that central IL1ß might not be related to the regulation of drinking behaviour and the hypothalamus-pituitary-adrenal axis. 6. The present study demonstrated that central IL1ß but not IL6 and IL8 might be related to the inhibition of feeding in chicks.

Lipopolysaccharide reduces food passage rate from the crop by a prostaglandin-independent mechanism in chickens.

1. We examined the effect of lipopolysaccharide (LPS), a component of Gram-negative bacteria, on food passage in the digestive tract of chickens (Gallus gallus) in order to clarify whether bacterial infection affects food passage in birds. 2. Food passage in the crop was significantly reduced by intraperitoneal (IP) injection of LPS while it did not affect the number of defecations, suggesting that LPS may affect food passage only in the upper digestive tract. 3. Similar to LPS, prostaglandin E2 (PGE2), one of the mediators of LPS, also reduced crop-emptying rate in chickens while it had no effect on the number of defecations. 4. Pretreatment with indomethacin, which is an inhibitor of cyclooxygenase (COX), a prostaglandin synthase, had no effect on LPS-induced inhibition of crop emptying. 5. IP injection of LPS did not affect the mRNA expression of COX2 in the upper digestive tract of chickens. 6. It is therefore likely that LPS and PGE2 reduced food passage rate in the crop by a prostaglandin-independent pathway in chickens.

Anorexia is Associated with Stress-Dependent Orexigenic Responses to Exogenous Neuropeptide Y.

Chicken lines that have been divergently selected for either low (LWS) or high (HWS) body weight at 56 days of age for more than 57 generations have different feeding behaviours in response to a range of i.c.v. injected neurotransmitters. The LWS have different severities of anorexia, whereas the HWS become obese. Previously, we demonstrated that LWS chicks did not respond, whereas HWS chicks increased food intake, after central injection of neuropeptide Y (NPY). The present study aimed to determine the molecular mechanisms underlying the loss of orexigenic function of NPY in LWS. Chicks were divided into four groups: stressed LWS and HWS on day of hatch, and control LWS and HWS. The stressor was a combination of food deprivation and cold exposure. On day 5 post-hatch, each chick received an i.c.v. injection of vehicle or 0.2 nmol of NPY. Only the LWS stressed group did not increase food intake in response to i.c.v. NPY. Hypothalamic mRNA abundance of appetite-associated factors was measured at 1 h post-injection. Interactions of genetic line, stress and NPY treatment were observed for the mRNA abundance of agouti-related peptide (AgRP) and synaptotagmin 1 (SYT1). Intracerebroventricular injection of NPY decreased and increased AgRP and SYT1 mRNA, respectively, in the stressed LWS and increased AgRP mRNA in stressed HWS chicks. Stress was associated with increased NPY, orexin receptor 2, corticotrophin-releasing factor receptor 1, melanocortin receptor 3 (MC3R) and growth hormone secretagogue receptor expression. In conclusion, the loss of responsiveness to exogenous NPY in stressed LWS chicks may be a result of the decreased and increased hypothalamic expression of AgRP and MC3R, respectively. This may induce an intensification of anorexigenic melanocortin signalling pathways in LWS chicks that block the orexigenic effect of exogenous NPY. These results provide insights onto the anorexic condition across species, and especially for forms of inducible anorexia such as human anorexia nervosa.

Chickens from lines artificially selected for juvenile low and high body weight differ in glucose homeostasis and pancreas physiology.

Artificial selection of White Plymouth Rock chickens for juvenile (day 56) body weight resulted in two divergent genetic lines: hypophagic low weight (LWS) chickens and hyperphagic obese high weight (HWS) chickens, with the latter more than 10-fold heavier than the former at selection age. A study was designed to investigate glucose regulation and pancreas physiology at selection age in LWS chickens and HWS chickens. Oral glucose tolerance and insulin sensitivity tests revealed differences in threshold sensitivity to insulin and glucose clearance rate between the lines. Results from real-time PCR showed greater pancreatic mRNA expression of four glucose regulatory genes (preproinsulin, PPI; preproglucagon, PPG; glucose transporter 2, GLUT2; and pancreatic duodenal homeobox 1, Pdx1) in LWS chickens, than HWS chickens. Histological analysis of the pancreas revealed that HWS chickens have larger pancreatic islets, less pancreatic islet mass, and more pancreatic inflammation than LWS chickens, all of which presumably contribute to impaired glucose metabolism.

Chickens from lines selected for high and low body weight show differences in fatty acid oxidation efficiency and metabolic flexibility in skeletal muscle and white adipose tissue.

OBJECTIVE: The Virginia lines of chickens have resulted from more than 55 generations of artificial selection for low (LWS) or high (HWS) juvenile body weight. We hypothesized that the relative hyperphagia and greater body weight in juvenile HWS chickens are associated with altered fatty acid oxidation efficiency and metabolic flexibility in tissues associated with energy sensing and storage, and relative cellular hypertrophy in white adipose tissue. METHODS: Hypothalamus, liver, pectoralis major, gastrocnemius, abdominal fat, clavicular fat and subcutaneous fat were collected from the juvenile (56-65 days old) LWS and HWS chickens for metabolic, gene expression and histological assays. RESULTS: The HWS chickens had reduced fatty acid oxidation efficiency in abdominal fat (P<0.0001) and reduced rates of oxidation in abdominal fat and gastrocnemius (P<0.0001) as compared with the LWS. There was reduced citrate synthase activity in white adipose tissue (P<0.0001) and greater metabolic inflexibility in skeletal muscle (P=0.006) of the HWS compared with the LWS. Greater pyruvate dehydrogenase kinase 4 (PDK4) and forkhead box O1A (FoxO1) mRNA were found in skeletal muscle and white adipose tissue of 56-day-old HWS than LWS. Expression of peroxisome proliferator-activated receptor γ (PPARγ) in all adipose tissue depots was greater (P<0.05) in LWS than in HWS chickens. The HWS chickens had larger (P<0.0001) and fewer (P<0.0001) adipocytes per unit area than the LWS. CONCLUSION: Compared with the LWS, the HWS chickens have impaired metabolic flexibility and fatty acid oxidation efficiency due to greater pyruvate dehydrogenase activity to accommodate the influx of acetyl-CoA from fatty acid oxidation in skeletal muscle and adipose tissue. These metabolic adaptations can be linked to differences in gene expression regulation, adipocyte cellularity and body composition between the lines, which may provide valuable insight into metabolic disorders in other species.

Intracerebroventricular injection of orexin-A, but not orexin-B, induces arousal of layer-type neonatal chicks.

In order to determine if orexins affect arousal in neonatal chicks, we intracerebroventricularly (ICV) injected either orexin-A or orexin-B to layer and broiler type chicks (Gallus gallus) and measured their behaviors and food intake following injection. Layer chicks treated with orexin-A at 0.2 and 2.0 nmol had increased arousal but their food intake was not affected. However, arousal was not affected in broiler chicks treated with orexin-A, but they spent less time feeding. When orexin-B was administered to layer and broiler chicks, neither had altered arousal and their food intake was not affected. Therefore, the orexin peptides may differentially affect arousal in the two stocks tested; orexin-A causes a stock dependant increase whereas orexin-B does not affect either.

Neuropeptide AF differentially affects anorexia in lines of chickens selected for high or low body weight.

The recently discovered anorectic effect of neuropeptide AF (NPAF) has not been studied in hypo-and hyperphagia animal models. The present study was designed to examine possible differences in appetite-related effects after central NPAF administration in lines of chickens that had undergone long-term divergent selection for low (LWS) or high (HWS) body weight and exhibit hypo- and hyperphagia, respectively. LWS chicks responded at a similar magnitude of food intake reduction to all doses of NPAF tested at all observation times. HWS chicks had an increased latency (150 min versus 30 min post injection) and an increased dose threshold of response (8 nmol versus 2 nmol) than LWS chicks. Water intake of LWS chicks was reduced in all doses tested at all observation times, whereas HWS chicks responded to the three doses of NPAF tested up to 60 min post injection, after which the decrease was sustained only at a dose of 8 nmol. In a comprehensive behaviour analysis, exploratory pecks, food pecks and locomotion were significantly reduced in both lines by NPAF, whereas sit time was increased in both lines. Other behaviours, including stand time, deep rest time and escape attempts, were not affected. These data suggest that the threshold of NPAF-induced anorexia is lower in LWS than HWS chicks and that NPAF-induced anorexia is a primary effect in both lines, and also support the hypothesis that differences exist in the central NPAF system between hypo- and hyperphagic individuals.

The anorectic effect of neuropeptide AF is associated with satiety-related hypothalamic nuclei.

Neuropeptide AF (NPAF), a member of the RFamide family, is encoded by the same gene as neuropeptide FF (NPFF), which causes short-term anorexia. However, reports on the role of NPAF on appetite-related process are lacking. Thus, i.c.v. injections of 4.0, 8.0 and 16.0 nmol NPAF were administered to chicks to observe its effect on food and water intake. Chicks treated with 8.0 and 16.0 nmol i.c.v. NPAF decreased both their food and water intake. Additionally, all doses of NPAF injected caused a similar reduction in whole blood glucose concentration 180 min after injection. In a second experiment, chicks that received i.c.v. NPAF had an increased number of c-Fos immunoreactive cells in the dorsomedial, paraventricular (magnocellular and parvicellular parts) and ventromedial nuclei. The arcuate nucleus and lateral hypothalamic area were not affected. In a third experiment, NPAF-treated chicks exhibited fewer feeding pecks and spent less time perching, whereas they spent an increased time in deep rest. Other behaviours, including exploratory pecking, escape attempts, defecations, distance moved, and time spent standing, sitting and preening, were not affected by NPAF injection. We conclude that NPAF causes anorectic effects that are associated with the hypothalamus.

Short-term anorexigenic effects of central neuropeptide VF are associated with hypothalamic changes in chicks.

The present study was designed to measure food and water intake, changes in hypothalamic chemistry, and other behaviour modifications after central injection of neuropeptide (NP) VF in broiler type chicks. In Experiment 1, chicks responded to central NPVF with a reduction in food intake for up to 90 min post injection. Water intake was unaffected. In Experiment 2, NPVF exerted a less potent and shorter duration of attenuated food intake than did the structurally related NPFF. In Experiment 3, 16.0 nmol NPVF reversed the prolactin-releasing peptide induced orexigenic effect. In Experiment 4, central NPVF treatment was associated with decreased c-Fos immunoreactivity in the lateral hypothalamus, whereas c-Fos immunoreactivity in the dorsomedial nucleus, infundibular nucleus (homologue to the mammalian arcuate nucleus) and ventromedial nucleus was increased. In Experiment 5, behaviours unrelated to ingestion including sit, stand, deep rest and locomotion were affected by central NPVF injection. Some of these behaviours are incompatible with ingestion and may contribute to hypothalamic associated perception of satiety after central NPVF. In conclusion, NVPF is a short-term regulator of appetite and its effects are associated with hypothalamic and behaviour changes in chicks.