Intracerebroventricular injection of orexins does not stimulate food intake in neonatal chicks

1. Recently, 2 novel neuropeptides were discovered, both derived from the same precursor by proteolytic processing, which bind and activate 2 closely related orphan G protein-coupled receptors, Named orexin-A and -B (Sakurai et al., 1998). Both stimulate food intake when administered centrally to rats. 2. Our aim was to elucidate whether central injection of mammalian orexin-A or -B stimulates food intake in the chick. 3. Under conditions of free access to food, orexin-A did not alter the food intake of chicks, but cumulative food intake was significantly suppressed by orexin-B. 4. The orexin-B was then administered to chicks deprived of food for 3 h to confirm its suppressive effect. No significant effect of orexin-B on food intake was detected. 5. Central injection of orexin-B did not modify food intake when appetite was stimulated by fasting. 6. Neither of these orexins appears to stimulate feeding in chicks.     

Roles of central histaminergic system in glucose metabolisms and food intake in sheep

The neurotransmitter histamine is thought to be involved in the homeostatic regulation of energy balance. The present study was conducted to examine whether the central histaminergic system is involved in the regulation glucose metabolisms and food intake in ruminants. Thioperamide, a presynaptic H3‐receptor antagonist, was intracerebroventricularly infused at a rate of 68 μg/min for 3 h, beginning at 11.00 hours, into castrated Suffolk rams (48–55 kg bodyweight) accustomed to being fed alfalfa hay cubes (2% of body weight) at 12.00 hours. The food intake was measured every 60 min for 2 h after the commencement of feeding (12.00 hours). Blood samples were taken through a jugular vein catheter every 10 or 20 min during the experiment. Plasma glucose levels were significantly (P < 0.05) greater in the thioperamide‐treated group than in the control. The post‐prandial insulin increment was significantly (P < 0.05) greater in the thioperamide‐treated group than in the saline‐treated control. The food intake of the thioperamide‐treated group was significantly (P < 0.05) less than that of the control in the period from 60 to 120 min after feeding. In conclusion, the central histaminergic system is involved in the regulation of glucose metabolisms and food intake in ruminants.     

Intracerebroventricular injection of mammalian motilin, melanin-concentrating hormone or galanin does not stimulate food intake in neonatal chicks

1. Several neural peptides are known to stimulate feeding behaviour in mammalian species. The aim of this study was to elucidate whether central injection of mammalian motilin, melanin-concentrating hormone (MCH) or galanin stimulates feeding in the neonatal chick. 2. None of the peptides applied here enhanced the food intake of the chick. 3. It is suggested that motilin, MCH and galanin, at least those of mammalian origin, may not regulate feeding in neonatal chicks, when administered to the central nervous system.     

Central regulation of food intake in the neonatal chick

Regulating food intake is complicated in animals including domestic birds. Just after hatching, neonatal chicks find their food by themselves and they can control food intake, since domestic chicken belongs to the precocial type of avian species. Thus, domestic chickens have relatively well-developed mechanisms of food-intake control at hatching. While many aspects of food-intake regulation in chickens appear similar to that in mammals, there are some responses that are unique to chickens. For instance, some neurotransmitters such as neuropeptide Y (NPY), orexin-A, orexin-B, motilin, melanin-concentrating hormone (MCH), galanin, growth hormone releasing factor (GRF) and ghrelin stimulate feeding in mammals. Only NPY strongly stimulates food intake in birds similar to that observed in mammals; however, both orexins, motilin, MCH and galanin failed to alter food intake of the chick. Moreover, GRF and ghrelin suppressed feeding of chicks. On the other hand, cholecystokinin (CCK), gastrin, glucagon-like peptide-1 (GLP-1), corticotropin-releasing factor (CRF), histamine, α-melanocyte stimulating hormone (α-MSH), leptin and bombesin are known to suppress feeding in mammals. These responses are similar to those of mammals except for leptin. Therefore, the inhibitory mechanisms for feeding are well conserved in chicks.     

Involvement of food intake in the decreased energy retention associated with single deficiencies of lysine and sulphur-containing amino acids in growing chicks.

1. Growth and energy utilisation were determined in growing chicks fed ad libitum on diets deficient either in lysine (5.95 g/kg) or in sulphur-containing amino acids (SAA, 3.5 g/kg). Food intake, body weight gain, energy retained as protein and as fat, and total energy retention were significantly (P less than 0.05) reduced by single deficiencies of either lysine or SAA. 2. Another two experiments were conducted to determine if the decreased total energy retentions in chicks fed on diets deficient in lysine (experiment 3) or SAA (experiment 4) were associated with reduced food intake, by using tube-feeding to control the amount and pattern of food consumption. Chicks fed on diets deficient in lysine or SAA retained less energy as protein and more energy as fat than the control chicks. Neither total energy retention nor heat increment was affected by these deficiencies. Total energy retention was proportional to metabolisable energy (ME) intake alone. 3. It is concluded that the decreased total energy retentions caused by single deficiencies of lysine and SAA were associated with decreased food intake.     

Central histaminergic system interplay with suppressive effects of immune challenge on food intake in chicken

1. The aim of the current study was to investigate the interaction of the lipopolysaccharide (LPS) and histaminergic systems on appetite regulation in broilers. Effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H₁ receptor antagonist), famotidine (histamine H₂ receptor antagonist) and thioperamide (histamine H₃ receptor antagonist) on LPS-induced hypophagia in broilers were studied.

2. A total of 128 broilers were randomly allocated into 4 experiments (4 groups and 8 replications in each experiment). A cannula was surgically implanted into the lateral ventricle. In Experiment 1, broilers were ICV injected with LPS (20 ng) prior to α-FMH (250 nmol). In Experiment 2, chickens were ICV injected with LPS followed by chlorpheniramine (300 nmol). In Experiment 3, broilers were ICV injected with famotidine (82 nmol) after LPS (20 ng). In Experiment 4, ICV injection of LPS was followed by thioperamide (300 nmol). Then, cumulative food intake was recorded until 4 h post-injection.

3. According to the results, LPS significantly decreased food intake. Chlorpheniramine significantly amplified food intake, and LPS-induced hypophagia was lessened by injection of chlorpheniramine. α-FMH, famotidine and thioperamide had no effect on LPS-induced hypophagia.

4. These results suggest that there is an interaction between central LPS and the histaminergic system where LPS-induced hypophagia is mediated by H₁ histamine receptors in 3 h food-deprived broilers.

     

Effect of oral administration of L-pipecolic acid on food intake in chicks and mice

It has been demonstrated that L-pipecolic acid (L-PA), a major metabolic intermediate of L-lysine (L-Lys) in the brain, is involved in the functioning of the γ-aminobutyric acid-ergic system. Previous study has shown that intracerebroventricular injection of L-PA suppressed feeding and induced sleep-like behavior in neonatal chicks. The present study examines whether the action of L-PA was induced by gavage in both chicks and mice. Oral administration of L-PA significantly inhibited food intake at 2 h after treatment in neonatal chicks, although no significant effect of L-Lys was detected. In mice, oral L-PA suppressed food intake compared to the control after 2 h of treatment. It was concluded that L-PA was effective for suppression of food intake after oral administration in both avian and mammalian species.     

Involvement of activin and inhibin in the regulation of food and water intake in the rat

The expression of activin and inhibin has been demonstrated in the hypothalamus, but their physiological roles in the brain remain to be elucidated. In the present study, involvement of activin and inhibin in the regulation of food and water intake was examined. Male rats were deprived of food or water for 12 and 60 hr, and mRNA levels of activin/inhibin alpha, betaA and betaB subunits in the hypothalamus were estimated by RT-PCR. Gene expression of alpha subunit transiently decreased at 12 hr of food deprivation, while it did not change during water deprivation. Food and water deprivation for 60 hr increased mRNA levels of betaA and betaB subunits, respectively. These results indicated that gene expression of each subunit was independently regulated. Injection of activin A (0.5 and 4.0 microg) into the third ventricle decreased food intake. Water intake was suppressed by 4.0 microg, but not 0.5 microg, of activin A. Intracerebroventricular injection of inhibin A (0.5 and 4.0 microg) decreased water intake in a dose dependent manner without affecting food intake, suggesting that inhibin could act independently of activin. Taken together, it is suggested that activin and inhibin take part in the central regulation of nutrient and fluid balance, though further study is needed to determine precise molecular species involved.     

Endocannabinoid and nitric oxide interaction mediates food intake in neonatal chicken

1. The aim of the current study was to investigate the interaction of the nitric oxide and cannabinoidergic systems on feeding behaviour in neonatal chicken.

2. A total of 6 experiments were designed to evaluate the interaction between cannabinoidergic and nitrergic systems on food intake in 3-h food-deprived (FD₃) neonatal chickens. In Experiment 1, chickens received intracerebroventricular (ICV) injections of saline, 2-arachidonoylglycerol (2-AG) (a CB₁ receptor agonist, 2 µg), l-arginine (nitric oxide precursor, 200 nmol) and co-administration of 2-AG + l-arginine. In Experiment 2, ICV injection of saline, 2-AG (2 µg), l-NAME (a nitric oxide synthesis inhibitor, 100 nmol) and their combination (2-AG + l-NAME) were applied to the birds. In Experiment 3, injections were saline, CB65 (a CB₂ receptor agonist, 1.25 µg), l-arginine (200 nmol) and CB65 + l-arginine. In Experiment 4, birds received ICV injection of saline, CB65 (1.25 µg), l-NAME (100 nmol) and CB65 + l-NAME. In Experiment 5, chickens were ICV injected with saline, l-arginine (800 nmol), SR141716A (a selective CB₁ receptor antagonist, 6.25 µg) and l-arginine + SR141716A. In Experiment 6, birds were injected with saline, l-arginine (800 nmol), AM630 (a selective CB₂ receptor antagonist, 5 µg) and l-arginine + AM630. Cumulative food intake was recorded until 2-h post injection.

3. ICV injection of CB₁ and CB₂ receptor agonists increased food intake. Co-injection of 2-AG + l-NAME increased the hyperphagic effects of CB₁ receptors. CB₂ receptor-induced food intake was not affected by co-administration of CB65 + l-NAME. l-Arginine decreased food intake and this effect was amplified by co-injection of l-arginine + SR141716A. However; CB₂ receptor antagonists had no effect on l-arginine-induced hypophagia.

4. The results suggest that there is an interaction between endogenous nitric oxide and the cannabinoidergic system on feeding behaviour which is mediated via CB₁ receptors in the neonatal chicken.

     

Potential of chemical regulation of food intake and body weight of broiler breeder chicks

1. Two experiments were performed to evaluate the potential of phenylpropanolamine hydrochloride and monensin sodium as appetite- and weight-control agents for Indian River broiler breeder chicks. 2. In experiment 1, a total of 300 day-old sexed broiler breeder chicks were individually weighed and placed in battery cages. They were randomly assigned to 5 dietary treatments, namely 0, 50, 100, 200 and 400 mg/kg of phenylpropanolamine hydrochloride added to a maize-soyabean meal basal diet. 3. In experiment 2, a total of 400 day-old sexed broiler breeder chicks were randomly assigned to 10 dietary treatments which were a combination of two concentrations of dietary crude protein (200 and 150 g/kg) and 5 different concentrations of added drugs in the diet, namely 0, 500 and 800 mg/kg of phenylpropanolamine hydrochloride and 200 and 300 mg/kg of monensin sodium. 4. Food consumption and body weight gain were significantly reduced by feeding diets containing the drugs but mortality was not significantly affected. Birds showed evidence of increased tolerance, with age, to phenylpropanolamine but not to monensin. 5. Monensin sodium, at high inclusion rates, was found to be a more potent and effective appetite- and growth-depressing agent for broiler breeder chicks than phenylpropanolamine and may have application in broiler breeder production using an ad libitum feeding programme.     

The effect of Nesfatin-1 on food intake in neonatal chicks: role of CRF<Subscript>1</Subscript> /CRF2 and H1/ H3 receptors

The present study was designed to determine the effect of central injection of Nesfatin-1 and corticotropin and histaminergic systems on food intake in neonatal meat-type chicks. In this study, 7 experiments were designed, each with 4 treatment groups. In experiment 1, four groups of chicks received the ICV injection of (A) phosphate-buffered saline (PBS), (B) Nesfatin-1 (10 ng), (C) Nesfatin-1 (20 ng) and (D) Nesfatin-1 (40 ng). In experiment 2, (A) PBS, (B) Astressin-B (CRF₁/CRF₂ receptors antagonist; 30 µg), (C) Nesfatin-1 (40 ng) and (D) Nesfatin-1?+?Astressin-B were injected. In experiments 3–6, chicken received ICV injection of the Astressin2-B (CRF₂ receptor antagonist; 30 µg), α-FMH (alpha fluoromethyl histidine; as inhibitor of histidine decarboxylase, 250 nmol), Chlorpheniramine (histamine H₁ receptors antagonist, 300 nmol), Famotidine (histamine H₂ receptors antagonist, 82 nmol) and Thioperamide (histamine H₃ receptors antagonist, 300 nmol) instead of the Astressin-B. Then the cumulative food intake measured until 120 min post-injection. According to the results, ICV injection of Nesfatin-1 dose dependently decreased food intake in neonatal chicks (P?<?0.05). Co-injection of the Nesfatin-1 and Astressin-B (CRF₁/CRF₂) inhibited Nesfatin-1 induced hypophagia (P?<?0.05). ICV inejction of the Nesfatin-1?+?Astressin-B significantly inhibited the effect of Nesfatin-1 on food intake (P?<?0.05). In addition, α-FMH and chlorpheniramine attenuated Nesfatin-1-induced hypophagia in chicks (P?<?0.05); while thioperamide significantly amplified the effect of Nesfatin-1 on food intake in chicks (P?<?0.05). These results suggested Nesfatin-1 has an anorectic effect in 3-hour food deprived neonatal meat-type chicks and this effect was mediated by corticotropin CRF₁/CRF₂ as well as histamine H₁ and H₃ receptors.     

Behavioral regulators in the brain of neonatal chicks

Domestic chickens are precocial and therefore have relatively well‐developed processes at hatch. As a result, neonatal chicks grow well at hatch with no parental care. The regulation of food intake in animals, including domestic birds, is complicated. Just after hatching, neonatal chicks find their food by themselves and they can control their food intake. Recently, prolactin releasing peptide and gonadotropin‐inhibitory hormone were confirmed as central orexigenic factors in the neonatal chick. Both peptides have a common structure as RFamide peptides. On the other hand, vasoactive intestinal peptide and pituitary adenylate cyclase‐activating polypeptide, both belonging to the glucagon superfamily, were recognized as inhibitory. Broiler chicks have either a greater capability to acclimatize to novel environments, or a blunted hypothalamus‐pituitary‐adrenal axis compared with layer chicks. These differences are explained by higher melatonin concentrations in the pineal gland and other parts of the brain of broiler chicks since melatonin attenuates the stress response. Stressful behavior in chicks can be attenuated by neurotransmitters or by nutrients such as creatine, phosphatidylserine, L‐serine and (‐)‐epigallocatechin gallate. It is suggested that the regulation of behavior is somewhat specific and can be attenuated by some manipulation in neonatal chicks.     

Involvement of corticosterone in food intake, food passage time and in vivo uptake of nutrients in the chicken (Gallus domesticus)

To evaluate the effect of corticosterone on nutrient transport, 10-week-old male chickens were grouped in 4 categories and treated as follows: sham-operated, adrenalectomised, corticosterone (4 mg/kg injected subcutaneously for 5 d) in both sham-operated and adrenalectomised. The food intake, food passage time and uptake of calcium, phosphorus and glucose were determined by standard procedures. Corticosterone administration to both sham-operated and adrenalectomised groups stimulated significantly higher food intake, delayed food passage time and increased uptake of calcium, phosphorus and glucose, as compared to sham-operated control and adrenalectomised groups. Corticosterone administration increased absorption of these nutrients significantly more in the adrenalectomised group than in the sham-operated controls. Corticosterone also significantly elevated the plasma concentrations of these nutrients. The responses to the hormone were significantly greater in adrenalectomised birds. It is concluded that corticosterone increases food intake and retention and the absorption of calcium, phosphorus and glucose in the alimentary tract.     

Effect of egg composition on hatchability and on growth and slaughter characteristics of meat-type chicks

1.?Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks’ development were studied.

2.?A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation.

3.?During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity.

4.?It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight.

5.?It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity.

6.?At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3·2 and 8·2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity.

7.?Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter.

8.?Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case.

9.?Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition.

10.?This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development.     

The effect of different dietary levels of a n-paraffin-grown yeast on the growth and food intake of broiler chicks

Sixteen groups, each of about 30 male or female Ross 1 chicks, were given pelleted diets containing 0, 5, 10 or 20% yeast in place of herring meal. The diets were given from 1 d of age for 4 weeks; from 4 to 8 weeks the birds were given a common broiler finisher diet. Replacing up to 10% herring meal by yeast did not significantly affect live‐weight at 4 weeks of age but food conversion efficiency was poorer with the diet containing 10% yeast. Birds given the diet containing 5% yeast to 4 weeks of age were significantly heavier at 8 weeks. The diet with 20% yeast significantly depressed growth at 4 and 8 weeks of age.

The use of yeast in broiler finisher diets was investigated in a second experiment. Birds similar to those used in the first experiment were given diets containing yeast at levels of 0, 5, 10 or 20% from 4 to 8 weeks of age. Live‐weight at 8 weeks was not significantly affected by level of yeast in the diet; food conversion efficiency was significantly better with the 20% yeast diet. Blood plasma uric acid levels were not affected by the level of yeast in the diet.     

Methylamine induced hypophagia is mediated via dopamine D1 and D2 receptors in neonatal meat chicks

Recently, methylamine has been found as an endogenous amine, which is controling food intake in mammals. However, there is no evidence about the effect of methylamine on feeding behavior in poultry. So, the present study was designed to evaluate the effect of intracerebroventricular (ICV) injection of methylamine and involvement of central methylamine/dopaminergic systems on feeding behavior in neonatal meat type chicks. In experiment 1, chicks were ICV injected with different doses of methylamine (0.48, 0.96, 1.44, 1.92 and 2.40 μmol). In experiment 2, chicks received a dose of either the control solution, 2.40 μmol methylamine, 125 nmol L-DOPA (dopamine precursor) or a combination of methylamine plus L-DOPA. Experiments 3–7 were similar to experiment 2 except that 150 nmol 6-OHDA (dopamine synthase inhibitor), 5 nmol SCH23390 (D1 receptor antagonist), 5 nmol AMI-193 (D2 receptor antagonist), 6.4 nmol NGB2904 (D3 receptor antagonist) and 6 nmol L-741, 742 (D4 receptor antagonist) were used instead of 125 nmol L-DOPA, respectively. Cumulative food intake was determined until 2 h post-injection. According to the results, methylamine significantly decreased food intake in a dose dependent manner (p < 0.05). The inhibitory effect of methylamine on food intake was significantly attenuated by 6-OHDA, SCH23390 and AMI-193 (P < 0.05), but NGB2904 and L-741, 742 had no effect on food intake induced by methylamine. In addition, hypophagic effect of methylamine significantly amplified by L-DOPA (P < 0.05). These results suggest that methylamine decrease food intake and there is an interaction between methylamine and dopaminergic system via D1 and D2 receptors in chickens.     

The relationship of food intake during growth and food intake at maturity with lactation food intake in a mouse model

Selection for increased leanness and improved food efficiency in pigs has resulted in a decreased voluntary food intake. It has been argued that voluntary food intake during lactation should be considered in sow breeding programmes. The aim of the present study was to investigate the phenotypic correlation of food intake during growth and food intake at maturity with maximum lactation food intake in a mouse model. A total of 179 records were available on female mice selected for litter size at birth (S-line) and non-selected control females (C-line) from 3 weeks of age to 21 days in lactation. Half of the litters were standardized to eight pups per litter (s) and half were not standardized (ns). Growth intake was measured as the average intake between 21 and 42 days of age, mature intake was measured from a linear regression of food intake against age between 42 and 69 days of age, and lactation intake was measured as a linear regression of food intake against days in lactation between 5 and 14 days in lactation. In both lines, females with a higher growth intake also had a higher mature intake (r = 0.63 to 0.75, P < 0.0001). Lactation intake was related with growth intake and mature intake in Sns females (r = 0.50 and 0.46, P < 0.01) and with growth intake in Ss females (r = 0.32, P < 0.05). In both lines, lactation intake was highly correlated with litter weight (r = 0.48 to 0.94, P < 0.001). Sns and Ss females with higher growth intake supported larger litter weights during lactation (r = 0.32 and 0.30, respectively, P < 0.05) and Sns females with higher mature intakes tended to support larger litter weights (r = 0.28, P = 0.060). It is suggested that lactating C-line females eat to support a given litter size, while S-line females support the maximum litter weight that is allowed for by their intake capacity, and still produce at high levels when litters are standardized. Since lactating sows mobilise body reserves, the relationship of food intake during growth with that during lactation may be reflected in the relationship between growth intake and body condition.     

Intracerebroventricular administration of chicken glucagon‐like peptide‐2 potently suppresses food intake in chicks

Glucagon‐related peptides, such as glucagon‐like peptide (GLP)‐1, GLP‐2 and oxyntomodulin (OXM), are processed from an identical precursor proglucagon. In mammals, all of these peptides are suggested to be involved in the central regulation of food intake. We previously showed that intracerebroventricular administration of chicken OXM and GLP‐1 significantly suppressed food intake in chicks. Here, we show that central administration of chicken GLP‐2 potently suppresses food intake in chicks. Male 8‐day‐old chicks (Gallus gallus domesticus) were used in all experiments. Intracerebroventricular administration of chicken GLP‐2 significantly suppressed food intake in chicks. Plasma glucose concentration was significantly decreased by chicken GLP‐2, whereas plasma nonesterified fatty acid concentration was significantly increased. Intracerebroventricular administration of chicken GLP‐2 did not affect plasma corticosterone concentration. In addition, the anorexigenic effect of GLP‐2 was not reversed by the corticotropin‐releasing factor (CRF) receptor antagonist α‐helical CRF, suggesting that CRF is not a downstream mediator of the anorexigenic pathway of GLP‐2 in chicks. Intracerebroventricular administration of an equimolar amount of GLP‐1 and GLP‐2, but not OXM, significantly suppressed food intake in both broiler and layer chicks. All our findings suggest that GLP‐2 functions as a potent anorexigenic peptide in the brain, as well as GLP‐1, in chicks.