Biomedical subjects

D M Denbow

Publications and source records attributed to D M Denbow.

At least 19 recordsLinked to original sources

PubMed2006

Interaction between nociceptin/orphanin FQ (N/OFQ) and GABA in response to feeding.

Nociceptin/orphanin FQ (N/OFQ) and gamma aminobutyric acid (GABA) agonists have been shown to increase feed intake in mammals and birds. In this study, the effect of intracerebroventricular (icv) injection of the potent NOP receptor agonists Nociceptin (1-13) NH(2), the GABA(A) receptor antagonist bicuculline, and the GABA(A) receptor agonist muscimol on feed intake in cockerels was investigated. The icv injection of N/OFQ and muscimol increases feed intake. The effect of N/OFQ on feed intake was strongly blocked by the injection of bicuculline whereas the effect of muscimol was stimulated by N/OFQ. These results suggest that N/OFQ may act at GABA(A) receptors or increases overflow of GABA in the brain of chickens to stimulate feeding.

Analysis of Variance↗

PubMed2005

Feeding and locomotion responses to centrally injected nociceptin/orphanin FQ in chicks.

Nociceptin/orphanin FQ (N/OFQ), the endogenous ligand of the opioid receptor-like receptor or nociceptin receptor (NOP), has been shown to induce feeding, locomotion, anti-stress and anxiolytic effects in rodents after central nervous system injection. In this study, the effect of intracerebroventricular (icv) injection of N/OFQ on feeding and locomotion behavior was evaluated in male broiler-type chickens. The icv injection of N/OFQ caused a moderate but significant increase in feed intake similar to the classical opioid peptides in rats. It also increased feed pecking frequency and feeding time 1 h after injection. Stepping, wing flapping and preening were not affected by N/OFQ. These results suggest that N/OFQ can act within the central nervous system of chickens to increase feed intake.

Analysis of Variance↗

PubMed2005

Brain creatine functions to attenuate acute stress responses through GABAnergic system in chicks.

The involvement of brain creatine in the adaptation to acute stress responses was investigated in chicks. In experiment 1, brain creatine content of chicks exposed to social separation stress was significantly increased compared with control chicks. The effects of i.c.v. injection of creatine (2 mug) on vocalizations, spontaneous activity and plasma corticosterone concentration in chicks under social separation stress were investigated in experiment 2. All measurements were attenuated by the i.c.v. injection of creatine compared with the controls under separation stress. Creatine also significantly decreased the active posture, but increased the motionless eye-opened posture, compared with the control. To clarify the relationship between creatine function and GABA receptors, the i.c.v. co-injection of creatine with picrotoxin, a GABA-A receptor antagonist, or CGP54626, a GABA-B receptor antagonist, was investigated in experiments 3 and 4. The effects of creatine on vocalizations and spontaneous activity were attenuated by co-injection of picrotoxin. In this case, active postures decreased by creatine were recovered by co-injection with picrotoxin. However, these effects were not obtained with CGP54626. The results suggest that central creatine functions within the CNS to attenuate the acute stress response by acting through GABA-A receptors in chicks.

Acute Disease↗

PubMed2004

Differences in catecholamine metabolism and behaviour in neonatal broiler and layer chicks.

1. To clarify the difference in behavioural activities and catecholamine metabolism between layer and broiler-type chicks two experiments were conducted. 2. In experiment 1, 1-d-old male layer and broiler chicks were placed in an open-field area and their responses were investigated for 10 min. The responses of the two strains were remarkably different, with broilers being less active than layers. Vocalisations rapidly decreased in broilers whereas those of layers remained elevated during the 10 min. 3. In experiment 2, 1-d-old chicks of both strains were killed and brain catecholamine concentrations were determined in three parts of the brain: telencephalon, optic lobe and brain stem. 4. In the whole brain, dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) were significantly higher in broilers. However, the values for norepinephrine (NE), epinephrine (E) and 4-hydroxy-3-methoxyphenylacetic acid (HVA) were similar between strains. The ratios of metabolite/precursor were also calculated: HVA/DOPAC was higher in layers, while NE/DA, E/NE and DOPAC/DA were not significantly different between strains. 5. These results suggest that behavioural activities differ greatly, while there are some differences in catecholamine metabolism between the two strains.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2004

Effects of long-term dietary lipids on mature bone mineral content, collagen, crosslinks, and prostaglandin E2 production in Japanese quail.

This study investigated the effects of long-term dietary lipids on mature bone mineral content, collagen concentration, crosslink levels, bone marrow and ex vivo prostaglandin E2 (PGE2) biosynthesis, as well as the relationship of PGE2 production to these bone formation parameters. One-month-old male Japanese quail were given a basal diet containing 1 of 4 lipid sources: soybean oil (SBO), hydrogenated soybean oil (HSBO), chicken fat (CF), or menhaden fish oil (FO) at 50 g/kg of the diet. At 8 mo of age, lipid treatments did not affect bone length, diameter, or weight in quail. Quail fed SBO or CF had significantly lower levels of mineral content in tibial bones compared with those given FO. Bone collagen level was significantly higher in quail consuming SBO than those given HSBO or CF. Collagen crosslink concentration was markedly increased in birds provided FO or HSBO compared with those fed SBO or CF. Prostaglandin E2 biosynthesis in bone organ culture and marrow were greatly increased in quail maintained on the SBO or CF diet compared with those given the FO or HSBO diet. Prostaglandin E2 production in the bone microenvironment was negatively correlated with tibial ash and collagen crosslinks but had a positive correlation with tibial collagen levels. These results support our previous findings that long-term exposure to diets high in SBO or CF impaired mature bone mechanical properties and histological characteristics. Further, the results suggest that long-term supplementation of SBO or CF in the diet had a significant adverse effect on mature bone metabolism, and that dietary lipids altered bone metabolism, perhaps partially by controlling the production of local regulatory factor in bone.

Animal Feed↗

PubMed2003

Intracerebroventricular administration of GABA-A and GABA-B receptor antagonists attenuate feeding and sleeping-like behavior induced by L-pipecolic acid in neonatal chicks.

It has been demonstrated that L-pipecolic acid (L-PA), a major metabolic intermediate of L-lysine (L-Lys) in the mammalian and chicken brain, is involved in the functioning of the GABAergic system. A previous study has shown that intracerebroventricular (i.c.v.) injection of L-PA suppressed feeding and induced sleep-like behavior in neonatal chicks; however, the precise relationship between the GABAergic system and L-PA has not been clarified. In the present study, the role of the GABA-A or GABA-B receptors in the suppression of food intake and induction of sleeping-like behavior by L-PA was investigated. Chicks were injected i.c.v. with the GABA-A antagonist picrotoxin or GABA-B antagonist CGP54626 along with L-PA. Although suppression of food intake by L-PA was restored partially by co-injection with CGP54626, but not picrotoxin, sleep-like behavior induced by L-PA was suppressed significantly by both antagonists. These results suggested that L-PA activated both GABA-A and GABA-B receptors, and GABA-B receptors alone contributed to food intake whereas both receptors contributed to sleep-like behavior.

Animals↗

PubMed2003

Behavioral effects of intracerebroventricular injection of oxytocin in birds.

In addition to playing a role as a hormone, oxytocin (OT) can act as a neurotransmitter. In birds, mesotocin (MT) replaces OT. There is both direct and indirect evidence for behavioral effects of OT in rats and humans, but there have been no such studies performed in birds. The purpose of this study was to define the effect of intracerebroventricular (i.c.v.) injection of OT (0-10 microg) on locomotion and feeding behaviors of broiler cockerels. Stepping and wing flapping were increased dose-dependently, but OT decreased preening. The i.c.v. injection of OT also caused a dose-dependent decrease in feed intake, feeding time and pecking frequency. These results suggest that OT might play a unique role in inducing a state of arousal in chickens that resembles fear/anxiety and also in reducing feed intake by acting on MT and/or vasotocin receptors.

Analysis of Variance↗

PubMed2003

Maternal dietary lipids alter bone chemical composition, mechanical properties, and histological characteristics of progeny of Japanese quail.

This study evaluated the effects of maternal dietary lipids on chemical components and mechanical and histological properties of tibia in progeny of Japanese quail fed different dietary lipids. Laying hens were fed a basal diet containing either soybean oil (SBO), hydrogenated soybean oil (HSBO), chicken fat (CF), or menhaden fish oil (FO) at 50 g/kg of the diet. The various maternal dietary lipid treatments did not affect growth of progeny at any developmental stage. There were no differences in tibial length, diameter, or collagen content. Tibial percentage ash was significantly higher in newly hatched progeny from hens fed the FO and HSBO diets. The levels of tibial deoxypyridinoline and total pyridinium crosslinks were higher in the FO and HSBO groups at hatch. At 7 d of age, the tibial deoxypyridinoline links remained higher in the FO group compared to the CF and SBO groups. Likewise, progeny from hens consuming the FO or HSBO diet had higher tibial shear force and stiffness at 7 and 14 d of age. There were no pronounced differences in tibial fracture energy and deflection among treatments. Maternal FO or HSBO enlarged the cartilaginous proliferative and hypertrophic zones of the tibial proximal end in newly hatched quail, which was accompanied by a thicker cortical bone in the diaphysis. However, the width of the hypertrophic zones tended to be smaller in these two groups coupled with improvement in trabecular density and cortical thickness in the proximal end and cortical density in the diaphysis at 3 wk of age. These results suggest that maternal dietary lipids altered bone development by influencing organic matrix quality and mineralization in embryos.

Adipose Tissue↗

PubMed2003

Long-term supplementation of various dietary lipids alters bone mineral content, mechanical properties and histological characteristics of Japanese quail.

The purpose of this study was to investigate the effects of long-term supplementation of fat in the diets on the fatty acid composition, chemical, mechanical, and histological properties of tibial bone. Month-old male Japanese quail were fed a basal diet containing either soybean oil (SBO), hydrogenated soybean oil (HSBO), chicken fat (CF), or menhaden fish oil (FO) at 50 g/kg of the diet and maintained on these diets for 7 mo. Lipid treatments did not affect body weight, food intake, tibial length, or diameter. The FO diet group had the highest percentage of tibial ash, and both the FO and HSBO significantly increased tibial mineral content compared to those given SBO or CF. The type and amount of fatty acids in the diets had a profound influence on fatty acid composition of lipids in tibial cortical bones. Quail fed FO had the highest concentration of (n-3) fatty acids, and those fed SBO were highest in (n-6) fatty acids. The HSBO diet, containing high level of trans-fatty acids, led to the accumulation of these fatty acids in bone. In quail, long-term supplementation of FO or HSBO increased tibial shear force and shear stress and improved histological cortical thickness and density when compared to those given SBO or CF. These results suggest that long-term exposure to a FO or HSBO diet have a significant beneficial effect on bone metabolism.

Animal Feed↗

PubMed2002

GABAergic control of food intake in the meat-type chickens.

This study examined the effects of intracerebroventricular injections of gamma-aminobutyric acid (GABA) agonists on short-term food intake in meat-type cockerels. In Experiment 1, birds were injected with various doses of muscimol, a GABA(A) agonist. In Experiment 2, the birds received bicuculline, a GABA(A) antagonist, prior to injection of muscimol. In Experiment 3, the effect of varying doses of baclofen, a GABA(B) agonist, on food intake was determined. The intracerebroventricular injection of muscimol caused a dose-dependent increase in food intake. This effect was significantly attenuated by pretreatment with bicuculline. Food intake was not affected by the intracerebroventricular injection of baclofen. These results suggest that GABA acts within the brain of broilers at a GABA(A), but not GABA(B), receptor to increase voluntary food intake.

Animals↗

PubMed2001

Interaction of corticotropin-releasing factor and glucagon-like peptide-1 on behaviors in chicks.

Both corticortropin-releasing factor (CRF) and glucagon-like peptide-1 (GLP-1) inhibit food intake of chicks, but they also produce other behaviors. The present experiments were undertaken to clarify the interaction of CRF and GLP-1 regarding their anorectic actions as well as other behaviors. In Experiment 1, birds were injected intracerebroventricularly (i.c.v.), following a 3-h fast, with either saline, 0.1 microg of CRF, 0.1 microg of CRF+0.1 microg of GLP-1 or 0.1 microg of CRF+1 microg of GLP-1, and food intake was measured for 2 h. The injection of CRF decreased food intake, and CRF injected with GLP-1 suppressed food intake for up to 2 h. Birds were treated similarly in Experiment 2 in which the doses of CRF and GLP-1 were reversed. GLP-1 strongly suppressed food intake, and this effect was augmented by coadministration of CRF. In Experiment 3, the behaviors of chicks injected with saline, CRF (0.1 microg), GLP-1 (0.1 microg) or CRF (0.1 microg)+GLP-1 (0.1 microg) were monitored for the numbers of steps, vocalization and locomotion. Chicks were excited, moved more and vocalized loudly following injection of CRF, whereas an opposite response was seen with GLP-1. The behaviors were intermediate following the coinjection of the two peptides. In conclusion, CRF and GLP-1 interact in the chick brain, but the response depends on the behavior being measured.

Animals↗

PubMed2001

Suppression of food intake induced by corticotropin-releasing factor family in neonatal chicks.

Corticotropin-releasing factor (CRF), urocortin and urotensin I share amino acid sequences, and they inhibit food intake in mammals. CRF plays a potent role in decreasing food intake in avian species, but the effects of urocortin and urotensin I have not been investigated. Therefore, the effect of these three peptides on food intake in the neonatal chick was compared. In Experiment 1, birds were injected intracerebroventricularly (i.c.v.) with either 0, 0.01, 0.1 or 1 microg of urocortin following a 3-h fast, and food intake was measured for 2 h post-injection. Food intake was suppressed in a dose-dependent manner. Using a similar design in Experiment 2, the effect of urotensin I was investigated. Urotensin I appeared to suppress food intake in neonatal chicks more than urocortin did. In Experiment 3, the efficacy of CRF, urocortin and urotensin I was directly compared using one dose, 0.1 microg. The results indicated that the suppressive effect on food intake was strongest for CRF followed by urotensin I, then urocortin. These results suggest that the structure of receptors for the CRF family in chicks may be somewhat different than in mammals.

Animals↗

PubMed2001

Feeding responses to several neuropeptide Y receptor agonists in the neonatal chick.

Neuropeptide Y is one of the most potent neuropeptides known to induce feeding in animals, and has been suggested to be a physiological signal for food intake. It has been also reported that intracerebroventricular injection of neuropeptide Y stimulates feeding behavior of the neonatal chick. There are many neuropeptide Y receptor agonists that have not been investigated in feeding response of the neonatal chick. The aim of this study is to elucidate whether central injection of several neuropeptide Y receptor agonists stimulates feeding of the neonatal chick over 2 h. We found that central injections of [Leu(31), Pro(34)]neuropeptide Y, peptide YY, human pancreatic polypeptide and rat pancreatic polypeptide significantly stimulated food intake of neonatal chicks throughout the 2-h post-injection period. Neuropeptide Y-(13-36) significantly stimulated feeding at 30 min, but not thereafter. [D-Trp(32)]neuropeptide Y stimulated feeding at 60 and 120 min, but not 30 min, post-injection. Central administration of rat pancreatic polypeptide, which does not increase food intake in rats, stimulated feeding in chicks. This result reflects structural differences of the neuropeptide Y receptor subtypes and/or differences in mechanisms stimulating feeding behavior between mammals and chickens. In conclusion, neuropeptide Y receptor agonists, except for neuropeptide Y-(13-36), are potent stimulators of food intake in the neonatal chick.

Animals↗

PubMed2001

Intracerebroventricular injection of ghrelin and growth hormone releasing factor inhibits food intake in neonatal chicks.

Growth hormone releasing factor (GRF) is known to stimulate feeding of rats. Ghrelin, a novel growth hormone (GH)-releasing acylated peptide, was recently isolated from rat stomach. It also stimulates the release of GH from the anterior pituitary through the GH secretagogue receptor (GHS-R) and feeding in the rat. We have investigated the effects of ghrelin and GRF on food intake of the neonatal chick. In Experiment 1, 0, 1.25, 2.5 and 5 microg of ghrelin were administered intracerebroventricularly (i.c.v.) to ad libitum fed birds. In Experiment 2, the effect of (i.c.v.) injection of 0, 1.25, 2.5 and 5 microg of GRF was investigated. Both peptides strongly inhibited food intake of the chick during the 2-h post-injection period. In the third experiment, 0, 0.5, 1 and 2 microg of ghrelin was injected i.c.v. in chicks previously deprived of food for 3 h. Food intake was again inhibited by ghrelin in a dose-dependent manner. These results suggest that the mechanisms for feeding of the neonatal chick through GH release are different from mammals.

Age Factors↗

PubMed2001

Relationships between feeding and locomotion behaviors after central administration of CRF in chicks.

The effect of intracerebroventricular injection of corticotropin-releasing factor (CRF) on various behaviors in chicks was determined at 15-min intervals over a 30-min period. Food intake of chicks was significantly decreased, and pecking rhythm was significantly delayed by CRF during the first 15-min post-injection. The similar tendencies were observed in the second 15-min post-injection, but not significantly different. Stepping, as an indicator of locomotion, was not different at 15-min post-injection, but was increased by CRF, thereafter. These results suggest that CRF acts within the central nervous system to decrease food intake and increase locomotion in the chick.

Animals↗

PubMed2001

Feeding, drinking, and temperature responses of chickens to intracerebroventricular histamine.

The present study examines the effects of intracerebroventricular injections of histamine (HA) and two HA antagonists, the H(1) receptor antagonist chloropheneramine maleate (CM) and the H(2) receptor antagonist cimetidine (CIM), on food and water consumption and body temperature in chickens. Single-Comb White Leghorns (SCWL) and broiler cockerels were utilized for these experiments. The first pair of experiments consisted of intracerebroventricular injections of HA and its effects on food and water consumption. HA was infused at dosages of 0, 25, 50, and 100 microg/10 microl of artificial cerebrospinal fluid (aCSF). HA significantly decreased food and water intake in a dose-dependent manner. The second pair of experiments examined the effects of HA on water intake while birds had no access to feed. Water intake was not significantly affected by intracerebroventricular injections of HA. The next pair of experiments examined the effects of HA on body temperature. In SCWL, body temperature was not affected by HA until 165 min postinjection when HA decreased temperature in a quadratic dose-response with maximum hypothermia being achieved at a dose of 25 microg. In contrast, HA increased body temperature in broilers beginning at 75 min postinjection. In the final series of experiments, the anorexia induced by HA was attenuated in SCWL and broilers with pretreatment of either CM or CIM. These results suggest that HA has an anorexigenic effect in SCWL and broiler cockerels, and this effect is mediated by both H(1) and H(2) receptors. Water intake is not directly affected by the intracerebroventricular injection of HA. Whereas HA increased body temperature in broilers, the response in SCWL is equivocal.

Animals↗

PubMed2001

Influence of ketone body and the inhibition of fatty acid oxidation on the food intake of the chick.

1. Fatty acid oxidation is known to be involved in the control of food intake in mammals. The effect of fatty acid oxidation on food intake in chickens was studied using a ketone body (beta-hydroxybutyrate (beta-HB)) and mercaptoacetate (MA) (an inhibitor of fatty acid oxidation). 2. Central and peripheral injection of beta-HB decreased food intake in a dose-dependent manner, while low doses of MA had no effect. Higher doses of MA inhibited feeding but also caused mortality. 3. These results indicate that ketone bodies act as an inhibitory signal for food intake in both the central and peripheral nervous systems but that inhibition of fatty acid oxidation may not be associated with feeding behaviour in chicks.

3-Hydroxybutyric Acid↗

PubMed2001

Maternal dietary lipids modify composition of bone lipids and ex vivo prostaglandin E2 production in early postnatal Japanese quail.

This study examined the effects of maternal dietary lipids on fatty acid composition and ex vivo prostaglandin E2 (PGE2) biosynthesis in bone tissues of progeny of Japanese quail. Laying hens were fed a basal diet containing soybean oil (SBO), hydrogenated soybean oil (HSBO), poultry fat (PF), or menhaden fish oil (FO) at 50 g/kg of diet. Fertilized eggs were incubated, and newly hatched quail were used for tibial fatty acid analysis and PGE2 measurement or were fed an identical diet until 2 wk of age. Yolks and tibiae of newly hatched quail from hens fed the SBO diet contained higher levels of total n-6 fatty acids and arachidonic acid [AA; 20:4(n-6)], whereas those from hens consuming the FO diet had increased concentrations of total n-3 fatty acids, eicosapentaenoic acid [EPA; 20:5(n-3)], docosapentaenoic acid [22:5(n-3)], docosahexaenoic acid [DHA; 22:6(n-3)], and total saturated fatty acids (SAT) but greatly reduced amounts of AA in egg yolks and tibiae. The maternal diet containing HSBO resulted in the accumulation of trans 18:1 egg yolks and tibiae of newly hatched quails. At 1 wk of age, the concentrations of EPA, DHA, and trans 18:1 in tibiae still reflected the maternal dietary fatty acid profile. At 2 wk of age, however, differences in fatty acid composition between treatments had disappeared. Addition of FO or HSBO to the maternal diet significantly lowered the ex vivo PGE2 production of tibiae in newly hatched quail compared to those from hens fed SBO or PF diet. These results suggest that maternal dietary lipids may have the potential to influence bone metabolism of embryos by modifying the fatty acid composition of this tissue.

Animal Feed↗