白石 純一

Summary When retroviruses infect germ cells and are transmitted to offspring, they become endogenous retroviruses (ERVs), whose insertions influence the expression of nearby genes. This study aimed to identify the genomic loci of ERVs in commercial broiler (Ross308), Tosa-Jidori, and Yakido chickens as well as to elucidate their impact on neighboring gene expression. Whole-genome data were obtained using next-generation sequencing, and candidate ERV loci were identified using the RetroSeq software. The Integrative Genomics Viewer tool was used to confirm target site duplications (TSDs) as evidence of ERV insertions. All reads within 200 bp of these TSDs were extracted to create contigs, confirming the presence of ERV sequences in the contigs using BLASTN. Gene expression levels were estimated by focusing on genes located near the 172 identified ERV loci. Among these, 119 loci were detected in broiler chickens, 80 in Tosa-Jidori chickens, and 86 in Yakido chickens, with 28 loci shared among them. Moreover, of these 172 loci, 75 were located within or near genes. Significant differences in gene expression were observed for N-acetylated alpha-linked acidic dipeptidase 2, glypican 6, and phospholipid scramblase family member 5 depending on the presence of ERV insertions. These results suggest that ERV insertions may influence the expression of certain genes, providing insights into the genetic diversity and evolutionary background of commercial and indigenous chickens. Understanding the effects of ERV insertions on gene expression can inform future genetic research and poultry breeding programs aimed at improving health and productivity. Author Summary Recently, endogenous retroviruses (ERVs) have gained significant attention as valuable markers for understanding genetic relationships and evolutionary processes among species. In this study, we investigated the loci and characteristics of ERVs in commercial and traditional Japanese chickens. ERVs are genetic remnants of ancient viral infections that can provide insights into avian evolution. We identified a total of 172 ERV loci in broiler, Tosa-Jidori, and Yakido chickens. Each chicken breed exhibited unique ERV insertion patterns. Notably, we found that ERV insertions near certain genes may influence gene expression. Our research enhances the understanding of how chickens have acquired traits, particularly through genetic mechanisms influenced by ERVs. These insights significantly contribute to our knowledge of biological evolution and the overall biodiversity of birds.

For the conservation of endangered avian species, developing gamete preservation technologies is essential. However, studies in oocytes have not been widely conducted. In this study, assuming that the ovaries are transported to a research facility after death, we investigated the effect of ovary storage on oocytes for the purpose of cryopreserving avian female gametes by using a chicken as a model of endangered avian species. After excision, the ovaries were stored at either a low temperature (4 °C) or room temperature for 1–3 days. Ovarian follicles stored under different conditions for each period were examined by neutral red staining, histology, and gene and protein expression analysis. In addition, the pH of the storage medium after preserving the ovaries was measured. Then, ovarian tissues were vitrified to determine the cryopreservation competence. Storing the ovarian tissues at 4 °C kept the follicles viable and morphologically normal for 3 days with slow decline. In contrast, although different storage temperature did not influence follicle viability and morphology after only 1 day of storage, ovarian tissues stored at room temperature rapidly declined in structurally normal follicles, and viable follicles were rarely seen after 3 days of storage. Gene and protein expression analysis showed that apoptosis had already started on the first day, as shown by the higher expression of CASP9 under room temperature conditions. Furthermore, high expression of SOD1 and a rapid decline of pH in the storage medium under room temperature storage suggested the influence of oxidative stress associated with low pH in this condition on the follicle survivability in hen ovarian tissues. Our cryopreservation study also showed that ovarian tissues stored at 4 °C could recover after cryopreservation even after 3 days of storage. The described storage conditions and cryopreservation methods, which preserve chicken follicle survival, will lay the foundation of ovarian tissue preservation to preserve the fertility of wild female birds.

To explore metabolic characteristics during the post-hatch developmental period, metabolomic analyses of breast muscle and plasma were performed in chickens. The most significant growth-related changes in metabolite levels were observed between seven and 28 days of age. Some of these metabolites are essential nutrients or reported as growth-promoting metabolites. In the muscle, two imidazole dipeptides—carnosine and its methylated metabolite, anserine—increased with the development. These dipeptide levels may be, in part, regulated transcriptionally because in the muscle mRNA levels of carnosine synthase and carnosine methylation enzyme increased. In contrast, taurine levels in the muscle decreased. This would be substrate availability-dependent because some upstream metabolites decreased in the muscle or plasma. In branched-chain amino acid metabolism, valine, leucine, and isoleucine decreased in the muscle, while some of their downstream metabolites decreased in the plasma. The polyamines, putrescine and spermidine, decreased in the muscle. Furthermore, mRNA levels associated with insulin/insulin-like growth factor 1 signaling, which play important roles in muscle growth, increased in the muscle. These results indicate that some metabolic pathways would be important to clarify metabolic characteristics and/or growth of breast muscle during the post-hatch developmental period in chickens.

We examined the effects of oral administration of L-citrulline (L-Cit) on plasma metabolic hormones and biochemical profile in broilers. Food intake, water intake, and body temperature were also analyzed. After dual oral administration (20 mmol/head/administration) of L-Cit, broilers were exposed to a high ambient temperature (HT; 30 ± 1°C) chamber for 120 min. Oral administration of L-Cit reduced (p < .001) rectal temperature in broilers. Food intake was increased (p < .05) by heat stress, but it was reduced (p < .05) by L-Cit. Plasma levels of 3,5,3'-triiodothyronine, which initially increased (p < .0001) due to heat stress, were reduced (p < .01) by oral administration of L-Cit. Plasma insulin levels were increased by heat exposure (p < .01) and oral L-Cit (p < .05). Heat stress caused a decline (p < .05) in plasma thyroxine. Plasma lactic acid (p < .05) and non-esterified fatty acids (p < .01) were increased in L-Cit-treated heat-exposed broilers. In conclusion, our results suggest that oral L-Cit can modulate plasma concentrations of major metabolic hormones and reduces food intake in broilers.

Objective: The aim of the present study was to investigate the effects of repeated thermal conditioning (RTC) at an early age on physiological and behavioral responses in chicks. Methods: Birds were assigned to one of the four treatments in which the RTC was exposure to 40 °C for 15 min daily. The treatments were 1) no thermal conditioning (control); 2) early exposure group (EE; RTC from 2 to 4 days of age); 3) later exposure group (LE; RTC from 5 to 7 days of age); or 4) both early and later exposure (BE; RTC from 2 to 7 days of age). All groups of chicks were challenged with high ambient temperature (40 °C for 15 min) at two weeks of age. Results: During heat challenge, initiation times of dissipation behaviors (panting and wing-drooping) were measured. Rectal temperature and respiration rate were measured after and before heat challenge. Hypothalamic samples and blood were collected at the end of heat challenges. Initiation times of dissipation behaviors and rectal temperature were not affected by the treatments. Increases in respiration rate in response to heat challenge were suppressed by early RTC treatment. There was no clear pattern of glucose levels in relation to thermal conditioning, whereas plasma corticosterone levels were decreased by early treatment (EE and BE groups). Hypothalamic thyrotropin releasing hormone gene expression was suppressed by early and later thermal conditioning and suppressed further by both early and later exposure. Neuropeptide Y gene expression in the BE group was lower than in the other groups, with a similar trend for corticotropin releasing hormone expression. Conclusion: Our results suggest that the effect of repeated thermal conditioning on the central thermoregulatory system depends on the number of times that chicks experienced conditioning. In addition, repeated thermal conditioning has greater effects on the acquisition of thermotolerance when conditioning occurs in chicks of two to four days of age in comparison with chicks of five to seven days of age.

This study aimed to determine whether glycyl-L-glutamine (Gly-Gln; beta-endorphin (30-31)), a non-opioid peptide derived from beta-endorphin processing, modulates neuropeptide Y (NPY)-induced feeding and hypothalamic mRNA expression of peptide hormones in male broiler chicks. Intracerebroventricular injection of NPY (235 pmol) generated a hyperphagic response in ad libitum chicks within 30 min. Co-administration of Gly-Gln (100 nmol) attenuated this response, inducing a 30 % decrease. This was not attributable to Gly-Gln hydrolysis because co-administration of glycine (Gly) and glutamine (Gln) had no effect on NPY-induced hyperphagia. Gly-Gln injected alone also showed no effect. The hypothalamic pro-opiomelanocortin mRNA expression in the co-injection group was significantly higher than that in the NPY alone group. These data indicate that endogenous Gly-Gln may contribute to regulate feeding behavior via the central melanocortin system in chicks and acts as a counter regulator of the neural activity in energy metabolism.

Two experiments were conducted to evaluate the usefulness of urinary creatinine levels as a criterion for the estimation of protein and amino acid requirements in poultry. Here we studied the effects of dietary precursor levels of creatinine, methionine and arginine, on urinary creatinine excretion in experiments. Both experiments used 15 Chunky broilers chicks that were 8 days old. The chicks were assigned to three dietary groups, with five chicks each, and were fed an experimental diet for 7 days. The experimental diets mainly consisted of corn and soybean meal, and contained deficient, adequate, or excessive methionine and arginine levels in experiments 1 and 2, respectively. Excreta were collected for the last 3 days of the feeding trial, and chicks were terminated by dislocation of the neck at the end of the feeding trial to collect their livers. Creatinine concentration in the excreta and hepatic L-arginineglycine amidinotransferase (AGAT) activities were determined. Urinary creatinine levels increased with increasing both dietary methionine and arginine levels from deficient to adequate recommended by Japanese feeding standard (P&lt;0.05), and then remained constant in experiments 1 and 2, respectively. The hepatic AGAT activity decreased when both dietary creatinine precursors levels were increased from deficient to adequate levels (p&lt;0.05), and then remained constant. These results suggested that creatinine excretion was changed with both increasing dietary methionine and arginine, dose-dependently.

The Tosa-no-Onagadori (briefly Onagadori) is one of the native Japanese chickens that is characterized by extremely long tail feathers in males, and thus designated as a "Special National Natural Treasure" of Japan. We investigated the timing of sexual maturity of the Onagadori and White Leghorn hens and the quality of the first 10 eggs laid by these young hens to obtain basic information for reproducing the Onagadori efficiently and also to assess their usefulness as research material for quantitative trait loci (QTL) analysis of egg-related traits. Onagadori and White Leghorn hens reached sexual maturity at around 237 and 192 days of age, respectively. The repeatability, a genetic parameter, of 22 egg quality traits including weight, size, and color of the eggshell, albumen, and yolk was estimated to be 0.14-0.61 and 0.15-0.83 for the Onagadori and White Leghorn, respectively, which indicated the stability of Onagadori eggs as well as the White Leghorn and further suggested that young Onagadori hens lay eggs with suitable quality to produce more offspring from their earliest egg laying stage. Principal component analysis with the 22 egg quality traits revealed five principal components explaining 79.70% of the total phenotypic variance. One-way ANOVA revealed differences between the two breeds in PC2 (heights of the albumen and yolk, size of the whole egg, and weights of the whole egg and albumen), PC3 (eggshell color), and PC4 (weight, thickness, and strength of the eggshell), which means that besides cultural assets the Onagadori is also valuable for QTL analysis of egg-related traits, for which phenotypic differences are quite useful for detecting corresponding loci.

To conserve the Tosa-no-Onagadori (briefly Onagadori), one of the native Japanese chicken breeds designated as a Special National Natural Treasure of Japan, time-dependent changes in genetic diversity and structure were analyzed based on 20 microsatellites. From three varieties (black-breasted white, black-breasted red, and white) of the Onagadori reared in Nankoku City, Kochi Prefecture, Japan, blood samples were collected in 1999, 2005, and 2009-2010. Significant genetic differentiation was recognized among breeders and among varieties in the whole Onagadori population, but it was not observed between years. Focusing on breeders, some populations showed decrease in allelic richness (AR) and expected heterozygosity (H-E) with advancing years. Focusing on varieties, AR of the black-breasted red variety showed significant loss from 1999 to 2010, resulting in the significant loss of AR in the whole Onagadori population. In contrast, the AR and H-E of the black-breasted white and white varieties were constant across sampling years. The D-A genetic distance among populations decreased with sampling years, and genetic homogeneity increased in the whole Onagadori population. Structure analysis supported K=2, dividing the genetic constitution into Onagadori-specific one and the rest. In the black-breasted white variety, the birds that have Onagadori-specific genetic composition increased with time. On the contrary, in the black-breasted red and white varieties surveyed in 2009-2010, there was no bird that showed Onagadori-specific genetic background of more than 75%. To maintain the Onagadori in Nankoku City for a long term, regular monitoring of genetic diversity and systematic reproduction using excellent black-breasted white birds that have the Onagadori-specific genetic composition should be continued.

It is known that thermal conditioning at an early age results in improved heat tolerance, and reduces mortality when re-exposed to heat in later life in chickens. However, the mechanism of thermal conditioning is not fully understood. The objective of this study was to investigate the effect of early thermal conditioning on physiological and behavioral responses in acute heat-exposed chicks. Six-day-old chicks (White Plymouth Rock) were exposed to high temperature at 40 degrees C for 3 h while control chicks were kept at 30 degrees C. Four days after treatment, both groups were challenged to high temperature at 40 degrees C for 15 min. We found that the initiation times for behavioral responses (panting and wing-droop posture) in experienced chicks were later than those in control. At the end of heat-exposure treatment, the rectal temperature in experienced chicks was lower than that in control while there was no difference in respiration rate between the groups. Compared with control, experienced chicks had a lower level of plasma corticosterone. Gene expression levels of brain-derived neurotrophic factor, thyrotropin-releasing hormone, interleulcin 6 and lipopolysaccharide-induced tumor necrosis factor were significantly lower in the brain of experienced chicks than in the control chicks. These results suggest that thermal conditioning may change response to subsequent heat exposure by altering the central thermoregulation system, resulting in an alleviation of heat stress.

To conserve the Tosa-no-Onagadori (briefly Onagadori), one of the native Japanese chicken breeds designated as a Special National Natural Treasure of Japan, time-dependent changes in genetic diversity and structure were analyzed based on 20 microsatellites. From three varieties (black-breasted white, black-breasted red, and white) of the Onagadori reared in Nankoku City, Kochi Prefecture, Japan, blood samples were collected in 1999, 2005, and 2009-2010. Significant genetic differentiation was recognized among breeders and among varieties in the whole Onagadori population, but it was not observed between years. Focusing on breeders, some populations showed decrease in allelic richness (AR) and expected heterozygosity (HE) with advancing years. Focusing on varieties, AR of the black-breasted red variety showed significant loss from1999 to 2010, resulting in the significant loss of AR in the whole Onagadori population. In contrast, the AR and HEof the black-breasted white and white varieties were constant across sampling years. TheDAgenetic distance among populations decreased with sampling years, and genetic homogeneity increased in the whole Onagadori population. Structure analysis supported K=2, dividing the genetic constitution into Onagadori-specific one and the rest. In the black-breasted white variety, the birds that have Onagadori-specific genetic composition increased with time. On the contrary, in the black-breasted red and white varieties surveyed in 2009-2010, there was no bird that showed Onagadori-specific genetic background of more than 75%. To maintain the Onagadori in Nankoku City for a long term, regular monitoring of genetic diversity and systematic reproduction using excellent black-breasted white birds that have the Onagadori-specific genetic composition should be continued. © 2014, Japan Poultry Science Association.

Since the presence of neuropeptide Y (NPY) in the central nervous system of chickens was demonstrated in 1988, numerous studies have shown that NPY functions as a strong orexigenic factor in this species. Similar to mammals, central administration of NPY robustly stimulates ingestive behavior in chickens in a dose-dependent manner. NPY is one of the most abundant peptides in chicken brain. Fasting leads to increased NPY gene expression in this organ. Six receptor subtypes for NPY (Y1, Y2, Y4, Y5, Y6 and Y7) have been identified in chickens and their binding characteristics have been investigated. Although pharmacological studies prove that appetite stimulation by NPY in mammals is mediated by receptors Y1 and Y5, there are conflicting data between the receptor expressions and pharmacological effects in chickens. This review provides an overview of the orexigenic effect of NPY and interrelationship with appetite-related signals, and summarizes the role of the NPYergic system on feeding regulation in chickens. © 2013 by Nova Science Publishers, Inc. All rights reserved.

The objective of the present study was to conduct amino acid profiling of two Japanese indigenous hens (Tosa-jidori TJI and Ukokkei UKO) and compared with a commercial hen (JL). Asparagine, leucine and proline levels in commercial layers were higher than those in both native Japanese chickens. Lysine and glutamate in UKO were higher than those in others and taurine was also higher than in JL. Serine in UKO was lower than those in others and methionine and cysteine were also lower than in JL. Arginine in TJI was lower than those in JL and UKO. No significant differences between breed/line were observed in histidine, threonine, glutamine, glycine, alanine, valine, isoleucine, tyrosine, phenylalanine and tryptophan. These results suggest that levels of dietary amino acid requirements might be different between native Japanese chickens. © Asian Network for Scientific Information, 2013.

Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.

The aim of this study is to elucidate whether insulin acts differentially within the central nervous system (CNS) of two types of commercial chicks to control ingestive behavior. Male layer and broiler chicks (4-day-old) were intracerebroventricularly (ICV) injected with saline or insulin under satiated and starved conditions. Feed intake was measured at 30, 60 and 120 min after treatment. Secondly, blood and hypothalamus were collected from both chick types under ad libitum feeding and fasting for 24 h. Plasma insulin concentration was measured by time-resolved fluoro-immunoassay. Hypothalamic insulin receptor mRNA expression levels were measured by quantitative RT-PCR. The ICV injection of insulin significantly inhibited feed consumption in layer chicks when compared with saline (P&lt;0.05), but not broiler chicks (P&gt;0.1). Plasma insulin concentration of both chick types significantly decreased following 24 h of fasting, while insulin concentrations in the broiler chicks were significantly higher compared to the layers fed under ad libitum conditions. Hypothalamic insulin receptor mRNA expression levels were significantly lower (P&lt;0.05) in broiler chicks than in layer ones under ad libitum feeding. Feed deprivation significantly decreased insulin receptor mRNA levels in layer chicks (P&lt;0.01), but not in broiler chicks (P&gt;0.1). Moreover, plasma insulin concentrations correlated negatively with hypothalamic insulin receptor protein expression in the two types of chicks fed ad libitum (P&lt;0.05). These results suggest that insulin resistance exists in the CNS of broiler chicks, possibly due to persistent hyperinsulinemia, which results in a down-regulation of CNS insulin receptor expression compared to that in layer chicks. (C) 2011 Elsevier Inc. All rights reserved.

It is important to quantify and estimate stressful stimulation because stress appears to limit productivity and welfare in poultry. The purpose of this study is to investigate the effect of acute isolation stress (5, 10 or 30 min) on the levels of blood parameters (glucose, free fatty acid (FFA) and corticosterone (CURT)) and diencephalic stress related peptide gene expressions (corticotrophin-releasing hormone (CRH) and arginine vasotocin (AVT)) in neonatal chicks. Although the isolation treatment did not affect concentration of plasma glucose (P &gt; 0.05), plasma FFA at 30 min after treatment was higher than control (P &lt; 0.01). The level of CURT increased significantly after 5 and 10 min of treatment (P &lt; 0.01), but that significant increase had disappeared in the chicks isolated for 30 min. The expression level of CRH in the chicks treated for 10 min, but not in the chicks treated for 5 and 30 min, was higher than in control (P &lt; 0.01), whereas there was no change in AVT mRNA for any of the isolation treatments (P &gt; 0.05). These findings demonstrate that high levels of CURT, through negative feedback, decrease CRH synthesis until 30 min after isolation, and further suggest that AVT expression in the diencephalons may not be applicable as an indicator of acute isolation stress in neonatal chicks.

Feeding behavior is managed by various neuropeptides and/or neurotransmitters within the central nervous system in vertebrates. It is proposed that central insulin acts as the negative-feedback regulator of appetite via the central melanocortin system in neonatal chicks. The present study investigated the localization of insulin receptors in the chick hypothalamus using immunohistochemistry. Immunostaining revealed hypothalamic neuron expressing insulin receptors in the paraventricular nucleus, ventromedial hypothalamus, lateral hypothalamus and infundibular nucleus, the avian equivalent of the mammalian arcuate nucleus. Additionally, double-staining immunohistochemistry in the infundibular nucleus revealed the presence of insulin receptors in both alpha-melanocyto stimulating hormone and neuropeptide Y neurons. Immunohistological analysis indicates that the insulinergic system in the chick hypothalamus contributes to feeding behavior and this system regulates both anorexigenic and orexigenic neuropeptides. Furthermore, the mechanisms of central insulin induced-feeding behavior contributes to the regulation of the melanocortin system in the chick infundibular nucleus. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Regulation of feed intake in chickens represents a complex homeostatic mechanism involving multiple levels of control. Understanding the regulation of feeding behavior can be a very important theme in animal production. Recently, a close evolutionary relationship between the peripheral and hypothalamic neuropeptides has become apparent. In the infundibular nucleus (the avian equivalent of the mammalian arcuate nucleus), the melanocortin system, which contains neuroendocrine neurons that regulate endocrine secretions by releasing substances, is an essential site in the brain for signals about the status of peripheral energy balance. The structure and function of many hypothalamic neuropeptides, melanocortins, neuropeptide-Y (NPY) and agouti-related protein (AGRP) have been characterized. This review provides as overview of the various effects and interrelationship of these central and peripheral neuropeptides, and summarizes the role of the melanocortin system on feeding regulation in chicks.

The objective of the present study was to survey embryonic and chick mortality in native Japanese chicken breeds (Onaga-dori; ONA, Tosa-jidori; TJI, Ukokkei; UKO and Hinai-dori; HNI). The embryonic mortality for each breed was 45.7 (ONA), 51.7 (TJI), 42.9 ( UKO) and 26.7% (HNI), throughout the incubation period. The ONA and TJI were found to show high mortality at the early embryonic stage (1-7 days) and it accounted for approximately 70% of total embryonic mortality. In the UKO, high mortality was detected at both the early and late (15-21 days) stages of incubation. Total chick mortalities up to 10 weeks of age were 68.0 (ONA), 62.8 (TJI), 26.4 (UKO) and 6.0% (HNI). In the ONA and TJI, higher mortalities were observed during the 2nd and 3rd week periods of life and reached more than half of their mortalities. The UKO was found to show the highest mortality during the 1st week of life. The HNI exhibited no specific mortality trends throughout the experiment period. These results suggest that embryonic and chick mortalities in Japanese chicken breeds are controlled by genetic factors. Changes in the management routines for each breed might reduce embryonic and chick mortalities and lead to the conservation of these rare Japanese chicken breeds.

The effects of Intra Cerebro Ventricular (ICV) injections of various glutamatergic receptor agonists were investigated using broiler chicks. ICV treatments with N-methyl-D-aspartate (NMDA: a selective agonist of NMDA-subtype of glutamatergic ionotropic receptors) stimulated feeding behavior of chicks in a dose-dependent manner. On the other hand, ICV administration of kainate (a selective agonist of kainate-subtype of glutamatergic ionotropic receptors), AMPA (a selective agonist of AMPA-subtype of glutamatergic ionotropic receptors) or ACPD (a metabotropic glutamate agonist) did not affect feed intake in meat-type chicks. These findings indicated the involvement of glutamate as a chemical mediator in the regulation of feeding behavior in the meat-type chick, possibly acting on the central nervous system in this line through NMDA-sensitive glutamatergic receptor.

Bungo, T. and Shiraishi, J. 2010. Effect of centrally administered methionine or related compounds on feeding behavior in chicks. J. Appl. Anim. Res., 38: 197-200. The effects of intracerebroventricular (ICV) injection of methionine (150-600 mg), and the related compounds, taurine (125-500 mg) or S-adenosyl-L-methionine (1-100 mg) were investigated using neonatal chicks. L-Methionine (600 mg) and D-methionine (300 and 600 mg) significantly increased food consumption at 30 min post injection. Taurine, one of the metabolites of methionine, failed to accelerate feeding behavior in chicks. In addition, S-adenosyl-L-methionine (100 mg), which is synthesized from methionine, tended to depress food intake in ad libitum chicks. These findings indicate the involvement of methionine as a chemical mediator in the regulation of food intake in chicks.

The relationship between taste sensitivity and the number of taste buds using a bitter tastant, quinine hydrochloride, was investigated in White Leghorn, Rhode Island Red, and broiler chickens. The White Leghorn and Rhode Island Red strains were able to perceive 2.0 mmol/L quinine hydrochloride, but the taste sensitivity of Rhode Island Red chickens was higher than that of White Leghorn chickens. Broiler chickens perceived 0.5 mmol/L quinine hydrochloride. The number of taste buds in the White Leghorn strain was the lowest, then the Rhode Island Red strain, with the number of taste buds highest in the broiler chickens. The number of taste buds was well correlated with bitter taste sensitivity. Therefore, we suggest that the number of taste buds is a vital factor in the perception of bitter taste and may be useful in selecting appropriate feeds for chickens.

To clarify the role of catecholaminergic systems in the regulation of feeding behavior in the neonatal chick, we investigated the action of central Noradrenalin (NA), Dopamine (DA), L-DOPA and Tyrosine (Tyr) on feed intake. Each substance or saline was acutely administered into the lateral ventricle (ICV) of chicks. Tyr, L-DOPA and DA did not significantly affect feed intake compared with saline control over the 60 min experimental periods. However, ICV injection of NA significantly stimulated feeding behavior in chicks at 30 min postinjection. These results suggest that the central NAergic system is involved in the control of feed intake, whereas the large increments of Tyr, L-DOPA and DA in. the brain. of chicks may not be involved in. NA induced hyperphagia.

The objective of this study was to compare the growth curve parameters for body weight of Japanese native chickens (Onaga-dori, Tosa-jidori, Ukokkei and Hinai-dori) using a non-linear model, Gompertz function. The data were collected from the four indigenous breeds together with two foreign breeds (White Plymouth Rock and Brown Leghorn) that were reared from 0 day old to 20 weeks of age. Breed differences were observed in the growth parameters. The predicted mature weight of the Hinai-dori was heavier than the other three Japanese native breeds. Tosa-jidori was observed to be late maturing and lighter at maturity, while Ukokkei was shown to have a higher growth rate. The development of growth curves for indigenous breeds may be useful in selecting native Japanese chickens that have rapid growth at early ages.

Recent research has revealed the anorexigenic effects of insulin in the central nervous system associated with changes in the expression of hypothalamic neuropeptides such as neuropeptide Y or alpha-melanocyte stimulating hormone. However, it is possible that monoaminergic system also participates in insulin-induced anorexia in chicks as suggested in early studies which show that changes in monoamine content play important roles in anorexia in mammals. To clarify the role of monoaminergic systems in the anorexic effect of central insulin in neonatal chicks, the levels of brain monoamines after intracerebroventricular injection of insulin were investigated. Although, there were no differences in the levels of adrenalin, 4-hydroxy-3-methoxyphenylacetic acid, serotonin and 5-hydroxyindole-3-acetic acid at each time point (p&gt;0.1) and the level of noradorenaline in chicks treated with insulin were significantly lower than that with saline at 30 min post-injection (p&lt;0.05). Conversely, dopamine and its metabolite, DOPAC were significantly increased in chicks treated with insulin when compared with the saline control (p&lt;0.01). However, co-injection of dopamine receptor antagonist prolonged insulin-induced anorexia at 60 and 120 min post injection (p&lt;0.05). These results indicate that the central noradrenalinergic but not dopaminergic and serotonergic systems may partly be involved in insulin-induced anorexia in neonatal chicks.

Nociceptin/orphanin FQ (N/OFQ) was identified in 1995 as the endogenous ligand for the orphan Gi/G coupled opioid receptor-like 1 receptor (NOPI). Exogenous N/OFQ increases food intake in mammals, but its effect and mode of action in chicks are not fully known. We report herein that N/OFQ(5.0 nmol) has a stimulatory effect on food intake in layer-type chicks over a 2-h period after intracerebroventricular (icv) injection. Thirty minutes after central injection of N/CFQ (5.0 nmol) the concentration of agouti-related protein (AGRP) mRNA in the diencephalon increased, while cocaine- and amphetamine-regulated transcript (CART) mRNA decreased. However, concentrations of neuropeptide Y, proopiomelanocortin and glutamate decarboxylase mRNAs, and of catecholamines and excitatory amino acids were not affected. Simultaneous administration of alpha-melanocyte stimulating hormone (alpha-MSH: 1.0 pmol), a competitor of ACRP, completely blocked the orexigenic effect of N/OFQ (5.0 nmol). These data suggest that N/OFQ functions in layer chicks as an orexigenic peptide in the central nervous system, and that the AGRP and the CART neurons may mediate this function, as in mammals. (C) 2009 Elsevier Inc. All rights reserved.

The aim of the present study was to determine if some naturally-occurring substitutions of amino acid residues of insulin could act differentially within the central nervous system (CNS) of neonatal chicks to control ingestive behavior. Intracerebroventricular (ICV) administration of chicken insulin (120 ng) inhibited food intake in ad libitum chicks over the 120-min experiment period. A lower dose (2 ng) also shows a suppressive effect at 60 min post-injection. but not at 30 and 120 min. Similar to chicken insulin, a higher dose of porcine insulin (20 ng) significantly inhibited food intake at 60 and 120 min post-injection, but a significant difference is not detected at 30 min post-injection. Treatment with human and bovine insulin had no effect in this study. Finally, we compared the effect of ICV injection of chicken and porcine insulin oil food consumption in starved chicks. The results of the present study indicate that chicken insulin has a higher potent ability to depress feeding behavior in the CNS compared with porcine. human, and bovine insulin. Therefore, it seems that the ranking in order of potency of the insulins on the anorexic effect in neonatal chick's is chicken insulin &gt; porcine insulin &gt; human insulin &gt; bovine insulin. It is suggested that the 8(th)-10(th) amino acids of the A-chain and/or the C-terminal amino acid of the B-chain in insulin have an important role in bioactivity in the CNS with special reference to feeding behavior.

It is known that N-terminal fragments of β-endorphin have biological activities, such as an antagonism effect of β-endorphin (1-31) on the secretion of hormones or thermoregulation in mammals. We studied the effects of the N-terminal fragments on feeding behavior in male broiler chicks. Intracerebroventricular administration of β-endorphin (1-27) (0.4 nmol) stimulated feeding behavior compared with saline control during the 60-min experimental period. β-Endorphin (1-17) (2.0 nmol) also increased food intake at 30 min postinjection. Co-injection of either β-endorphin (1-27) or (1-17) was effective in reducing full-length β-endorphin-induced feeding in chicks. These data suggest that the N-terminal fragments of β-endorphin act as a partial agonist, and may regulate the activity of the central opioidergic system in chicks. © 2008 Elsevier Ireland Ltd. All rights reserved.

Pro-opiomelanocortin (POMC) neurons in the hypothalamus are direct targets of peripheral satiety signals, such as leptin and insulin in mammals. The stimulation of these signals activates hypothalamic POMC neurons and elevates POMC-derived melanocortin peptides that inhibit food intake in mammals. On the other hand, it has been recognized that β-endorphin, a post-translational processing of POMC, acts in an autoreceptor manner to the μ-opioid receptor (MOR) on POMC neurons, diminishing POMC neuronal activity in mammals. Recently, we found that central insulin functions as an anorexic peptide in chicks. Thus, the present study was done to elucidate whether β-endorphin affects the activation of POMC neurons by insulin in neonatal chicks. Consequently, quantitative real-time PCR analysis shows that intracerebroventricular (ICV) injection of insulin with β-endorphin significantly decreases brain POMC mRNA expression when compared with insulin alone. In addition, co-injection of MOR agonist (β-endorphin or [d-Ala2, N-MePhe4, Gly5-ol]-enkephalin (DAMGO)) significantly attenuates insulin-induced hypophagia in chicks. These data suggest that β-endorphin regulates the activity of the central melanocortin system, and its activation may provide an inhibitory feedback mechanism in the brain of neonatal chicks. © 2008 Elsevier Ireland Ltd. All rights reserved.

The effects of intracerebroventricular injection of L-tryptophan on feeding behavior and the levels of brain neurotransmitters (amino acids or monoamines) were investigated in ad libitum chicks. The tryptophan treatment (3 or 6 mu mol) significantly inhibited food intake in chicks at 30min postinjection. The levels of serotonin (5-HT) and its metabolite, 5-dihydroxyindolacetic acid, in chicks treated with tryptophan were significantly higher than those with saline at 15 min postinjection. However, there were no differences in the levels of catecholamines (adrenaline, noradrenaline and dopamine) and amino acid neurotransmitters (e.g., gamma-aminobutyric acid, glycine and glutamic acid). The tryptophan-induced anorexia tended to be attenuated by the 5-HT2A receptor antagonist ketanserin (10 mu g). These results suggest that the administration of tryptophan into the chick brain produces the anorexic effect, and that the change in brain 5-HT content may be involved in this anorexia.

Growing evidence suggests that insulin interacts with both orexigenic and anorexigenic peptides in the brain for the control of feeding behavior in mammals. However, the action of central insulin in chicks has not yet been identified. In the present study, we investigated the effects of central injection of insulin on feeding behavior in chicks. Intracerebroventricular (ICV) administration of insulin, at doses that do not influence peripheral glucose levels, significantly inhibited food intake in chicks. Central injection of insulin in chicks significantly increased expression of pro-opiomelanocortin (POMC) mRNA, and decreased that of neuropeptide Y (NPY) mRNA. Finally, co-injection of the melanocortin antagonist (SHU9119 or HS014) prevented the reduction in food intake caused by ICV administration of insulin. These data suggest that insulin functions in chicks as an appetite-suppressive peptide in the central nervous system, and that the central melanocortin system mediates this anorexic effect of insulin, as in mammals. (C) 2007 Elsevier Inc. All rights reserved.

β-Endorphin is an endogenous ligand for both mu- and delta-opioid receptors (MOR and DOR), and has an important role in feeding behavior in the central nervous system in mammals. The present study was done to elucidate whether central injection of β-endorphin enhances feeding behavior in neonatal chicks and to investigate the interaction with the MOR and DOR. We found that the intracerebroventricular (ICV) injection of β-endorphin (50 pmol) significantly stimulated food intake in neonatal chicks during the 60-min period postinjection. In addition, the orexigenic effect of β-endorphin was significantly attenuated by the MOR, but not by the DOR antagonist. These results indicate that the administration of β-endorphin into the chick brain produces the orexigenic effect through the MOR. Copyright © 2008, Japan Poultry Science Association.