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1.
Br Poult Sci ; 64(1): 47-55, 2023 Feb.
Article de Anglais | MEDLINE | ID: mdl-36129068

RÉSUMÉ

1. This study assessed 1) the effects of Paracoccus carotinifaciens supplementation containing high astaxanthin levels on egg production performance and quality, 2) dynamics of carotenoids levels in the egg yolk and 3) taste of astaxanthin-rich egg yolk.2. Laying hens were fed diets containing different levels of P. carotinifaciens-derived astaxanthin (ASX; 0, 2, 4, 8, or 16 ppm) for 28 d (experiment 1) or a diet containing 16 ppm astaxanthin for 28 d followed by a 0 ppm astaxanthin diet for 28 days (experiment 2).3. Production performance, egg quality and egg yolk carotenoid levels were examined in experiment 1 (Ex1) and the dynamics of egg yolk carotenoid levels and egg yolk taste in experiment 2 (Ex2).4. ASX supplementation did not affect production performance or egg quality. ASX levels in the egg yolk became saturated after seven days of 16 ppm supplementation and decreased to less than one-tenth of the saturated levels seven days after supplementation cessation. Supplementation with 16 ppm ASX for 28 d did not affect egg yolk taste.5. Supplementation resulted in the production of ASX-rich eggs for a brief period without affecting production performance, egg quality or taste. Understanding the time taken for the incorporation of ASX into egg yolks is beneficial for value-added egg production and may help in minimising supplementation costs.


Sujet(s)
Poulets , Ovule , Femelle , Animaux , Jaune d'œuf , Régime alimentaire/médecine vétérinaire , Caroténoïdes , Compléments alimentaires/analyse , Aliment pour animaux/analyse , Oeufs/analyse
2.
Poult Sci ; 98(6): 2570-2576, 2019 Jun 01.
Article de Anglais | MEDLINE | ID: mdl-30753716

RÉSUMÉ

Intestinal glucose absorption varies with growth; however, the dynamics of these variations has not been yet fully elucidated in broiler chickens. The present study aimed to compare jejunal glucose uptake and maltose digestion in broilers of 2 different ages, i.e., 1- vs. 5 wk old. Oral D-maltose gavage, everted sac, and Ussing chamber experiments were carried out to investigate intestinal glucose absorption and mRNA expression of glucose-transport-related genes as well as jejunal maltase activity. Upon gavage, glucose concentrations peaked at 10 min post-administration in 1-wk-old chicks, while they peaked at 40 min in 5-wk-old chickens. Glucose concentrations at 10 min were significantly higher in the 1-wk-old chicks (P = 0.010). Using the everted sacs experimental setup, 5 intestinal regions i.e., duodenum, proximal jejunum, distal jejunum, proximal ileum, and distal ileum, were targeted to examine D-maltose digestion and glucose transport across the intestinal mucosa. In the distal and proximal ileum, glucose concentrations were found to be significantly higher in the serosal compartment of the 1-wk-old chicks upon incubation with D-maltose (25 mM) (P < 0.05), while in the mucosal compartment the levels were significantly higher in the 5-wk-old chickens (P < 0.05). An Ussing chamber setup was employed to measure glucose-induced short-circuit current (ΔIsc) in the mucosal epithelium of the jejunum. In response to the addition of D-maltose (10 mM) into the mucosal compartment, ΔIsc was significantly higher in the 1-wk-old chicks (P = 0.018). Furthermore, no variations in jejunal maltase activity were observed between the 2 age groups. While jejunal glucose absorption was lower in the 5-wk-old chickens, the mRNA expression levels of jejunal SGLT1, GLUT2, and Na+/K+-ATPase did not show any significant differences between the 2 age groups. Our results suggest that the active transport of glucose across the jejunal epithelium decreases upon growth in broiler chickens but is not accompanied by any variations in maltase activity or in the expression of glucose-absorption-related genes.


Sujet(s)
Poulets/métabolisme , Glucose/métabolisme , Jéjunum/métabolisme , Maltose/métabolisme , Facteurs âges , Phénomènes physiologiques nutritionnels chez l'animal , Animaux , Transport biologique actif , Poulets/génétique , Poulets/croissance et développement , Digestion/physiologie , Épithélium/métabolisme , Expression des gènes , Muqueuse intestinale/métabolisme , Mâle , ARN messager
3.
Benef Microbes ; 10(1): 89-100, 2019 Feb 08.
Article de Anglais | MEDLINE | ID: mdl-30353739

RÉSUMÉ

Intestinal barrier function is closely related to intestinal health and diseases. Recent studies demonstrate that some probiotic and commensal bacteria secrete metabolites that are capable of affecting the intestinal functions. The present study examined an enhancing effect of bioactive factors secreted by Bifidobacterium breve strain B-3 on the intestinal tight junction (TJ) barrier integrity in human intestinal Caco-2 cells. Administration of conditioned medium obtained from B. breve strain B-3 (B3CM) to Caco-2 cells for 24 h increased trans-epithelial electrical resistance (TER), a TJ barrier indicator, across their monolayers. Immunoblot, immunofluorescence, and qPCR analyses demonstrated that B3CM increased an integral TJ protein, claudin-4 expression. In luciferase reporter assay, the administration of B3CM enhanced the claudin-4 promoter activity, indicating the transcriptional upregulation of claudin-4. Site-directed mutation of specificity protein 1 (Sp1) binding sites in the claudin-4 promoter sequence and suppression of Sp1 expression by siRNA technology clearly reduced the enhancing effect of B3CM on claudin-4 promoter activity. Liquid chromatography/mass spectrometry detected a significant amount of acetic acid in B3CM (28.3 mM). The administration of acetic acid to Caco-2 cells partially mimicked a B3CM-mediated increase in TER, but failed to increase claudin-4 expression. Taken together, bioactive factors secreted by B. breve B-3 enhanced the TJ barrier integrity in intestinal Caco-2 cells. Transcriptional regulation of claudin-4 through Sp1 is at least in part one of the underlying molecular mechanisms. In addition, acetic acid contributes to the B3CM-mediated barrier effect independently of claudin-4 expression.


Sujet(s)
Bifidobacterium breve/métabolisme , Muqueuse intestinale/métabolisme , Probiotiques/métabolisme , Jonctions serrées/métabolisme , Cellules Caco-2 , Claudine-4/génétique , Milieux de culture conditionnés/pharmacologie , Humains , Muqueuse intestinale/effets des médicaments et des substances chimiques , Perméabilité/effets des médicaments et des substances chimiques , Régions promotrices (génétique) , Facteur de transcription Sp1/génétique , Facteur de transcription Sp1/métabolisme , Jonctions serrées/effets des médicaments et des substances chimiques , Activation de la transcription/effets des médicaments et des substances chimiques
5.
Kyobu Geka ; 65(5): 427-9, 2012 May.
Article de Japonais | MEDLINE | ID: mdl-22569504

RÉSUMÉ

A 55-year-old man underwent rectal amputation for rectal cancer in August 2005. A tiny thin-walled cavity lesion in his left S1+2 was found on computed tomography (CT) of the chest in November 2008. The cavity lesion in the left S1+2 gradually increased in size over 3 months and positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) showed FDG accumulation at the lesion. Videoassisted thoracoscopic (VATS) wedge resection was performed to make a definite diagnosis in March 2009. The pathological findings revealed a metastatic lung tumor from the rectal cancer. It is necessary to consider the possibility of metastatic lung tumors in a case with the cavity lesions especially in patients with a history of colon cancer.


Sujet(s)
Tumeurs du poumon/anatomopathologie , Tumeurs du poumon/secondaire , Tumeurs du rectum/anatomopathologie , Humains , Mâle , Adulte d'âge moyen
6.
Kyobu Geka ; 63(12): 1087-9, 2010 Nov.
Article de Japonais | MEDLINE | ID: mdl-21066854

RÉSUMÉ

A 74-year-old man was admitted to our hospital in order to treat a mediastinal mass and 2 ground-glass attenuations in the right upper lobe detected by chest X-ray and computed tomography (CT). Partial resection of right lung and thymectomy were performed. The mediastinal mass and 2 ground-glass attenuations in the right upper lobe proved to be thymoma and bronchioloalveolar carcinomas, respectively by pathology.


Sujet(s)
Adénocarcinome bronchioloalvéolaire/complications , Tumeurs du poumon/complications , Tumeurs primitives multiples , Thymome/complications , Tumeurs du thymus/complications , Sujet âgé , Humains , Mâle
7.
J Anim Sci ; 88(6): 2103-7, 2010 Jun.
Article de Anglais | MEDLINE | ID: mdl-20190166

RÉSUMÉ

The roles of pancreatic polypeptide (PP) have not been determined in ruminant animals. The aim of the present study was to examine the role of PP in the regulation of ghrelin secretion in sheep. Two experiments were conducted using four 2-yr-old Suffolk wethers fed a maintenance diet of alfalfa hay cubes. In Exp. 1, the effects of feeding on blood ghrelin and PP concentrations were examined in scheduled-fed sheep. Blood samples were collected every 10 min from 30 min before to 360 min after feeding. Plasma PP concentrations were transiently increased from the preprandial average value to the values from 30 to 60 min after feeding and gradually decreased (P < 0.05) to stable values from 150 to 180 min. The values from 30 to 60 min were greater (P < 0.05) than those from 150 to 360 min. In contrast, plasma ghrelin concentrations were gradually decreased (P < 0.01) by feeding. The values from 60 to 360 min were less (P < 0.01) than the preprandial average value. In Exp. 2, the effects of continuous PP infusion on ghrelin secretion were examined in feed-deprived sheep. The animals were deprived of feed for 48 h before PP infusion. The PP-treated group intravenously received synthetic bovine PP at a rate of 10 pmol.kg(-1 )of BW.min(-1) for 180 min. Blood samples were collected every 10 min from 30 min before to 180 min after the commencement of PP infusion. Plasma PP concentrations reached a plateau within 30 min after the commencement of PP infusion. Plasma ghrelin concentrations were decreased (P = 0.002, 0.016, 0.007) by PP infusion at 160, 170, and 180 min, respectively. In conclusion, plasma ghrelin and PP concentrations were decreased and increased, respectively, in response to feeding in ruminant animals. Furthermore, PP could depress ghrelin secretion.


Sujet(s)
Privation alimentaire/physiologie , Ghréline/physiologie , Polypeptide pancréatique/pharmacologie , Ovis/physiologie , Animaux , Ghréline/sang , Ghréline/métabolisme , Modèles linéaires , Mâle , Polypeptide pancréatique/sang
8.
Kyobu Geka ; 62(5): 427-9, 2009 May.
Article de Japonais | MEDLINE | ID: mdl-19425388

RÉSUMÉ

A 47-year-old man with a history of surgery for gastric cancer had enlarging right hilar tumor. Primary or metastatic malignant tumor was suggested and the right upper lobectomy with systematic nodal dissection was performed. Pathological diagnosis was lymph node metastasis of the squamous cell carcinoma. He received no additional treatment, and is well without recurrence 5 years after resection.


Sujet(s)
Carcinome épidermoïde/secondaire , Tumeurs du poumon/secondaire , Métastase lymphatique/anatomopathologie , Métastases d'origine inconnue , Humains , Mâle , Adulte d'âge moyen
9.
Domest Anim Endocrinol ; 37(1): 55-60, 2009 Jul.
Article de Anglais | MEDLINE | ID: mdl-19342191

RÉSUMÉ

The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 microg ghrelin/kg body weight (BW), with and without GHRH at 0.25 microg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 microg/kg BW) and high (6.6 microg/kg BW) doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P<.05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P<.01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals.


Sujet(s)
Jeûne , Aliments , Ghréline/administration et posologie , Hormone de libération de l'hormone de croissance/pharmacologie , Hormone de croissance/métabolisme , Ovis/physiologie , Animaux , Acide gras libre/sang , Dosage fluoroimmunologique , Hormone de croissance/sang , Cinétique , Mâle
10.
Kyobu Geka ; 62(2): 169-71, 2009 Feb.
Article de Japonais | MEDLINE | ID: mdl-19202942

RÉSUMÉ

A 52-year-old woman was admitted to our hospital because of an abnormal shadow on chest X-ray. Chest computed tomography scan and magnetic resonance imaging demonstrated an anterior mediastinal tumor. The tumor was extirpated completely with combined partial resection of the left lung through a median sternotomy. Microscopically, the tumor was diagnosed thymic cancer, basaloid carcinoma. The patient was treated with combination chemotherapy and radiation, postoperatively. We reported a case of thymic carcinoma.


Sujet(s)
Carcinome transitionnel/chirurgie , Tumeurs du thymus/chirurgie , Carcinome transitionnel/diagnostic , Carcinome transitionnel/anatomopathologie , Traitement médicamenteux adjuvant , Imagerie diagnostique , Femelle , Humains , Adulte d'âge moyen , Radiothérapie adjuvante , Sternum/chirurgie , Thymectomie , Tumeurs du thymus/diagnostic , Tumeurs du thymus/anatomopathologie , Résultat thérapeutique
11.
Kyobu Geka ; 61(13): 1165-7, 2008 Dec.
Article de Japonais | MEDLINE | ID: mdl-19068709

RÉSUMÉ

A 52-year-old man was admitted to our hospital because of an abnormal shadow on chest X-ray. Chest computed tomography scan and broncho-fiberscopic examination revealed a tumor at the left main bronchus. The tumor was removed completely by partial resection of the left main bronchus with thoracotomy. Historical finding of the resected specimen revealed a benign pleomorphic adenoma of the bronchus. The postoperative course was un-eventful for 9 years. We reported a rare case of pleomorphic adenoma of the bronchus.


Sujet(s)
Adénome pléomorphe/chirurgie , Tumeurs des bronches/chirurgie , Adénome pléomorphe/anatomopathologie , Tumeurs des bronches/anatomopathologie , Humains , Mâle , Adulte d'âge moyen
12.
Kyobu Geka ; 61(12): 1026-9, 2008 Nov.
Article de Japonais | MEDLINE | ID: mdl-19048901

RÉSUMÉ

Mucosa-associated lymphoid tissue (MALT) lymphoma of the lung is rare. We present a case of MALT lymphoma of the lung. A 64-year-old man was admitted to our hospital because of an abnormal shadow on chest X-ray. He was performed transbronchial lung biopsy (TBLB) in our hospital, but the results was not diagnostic. We performed surgical biopsy using thoracoscopy due to the possibility of malignancy. The pathological diagnosis was MALT lymphoma. He underwent an chemotherapy after the operation and has been followed up at an outpatient for 8 years.


Sujet(s)
Tumeurs du poumon/anatomopathologie , Lymphome B de la zone marginale/anatomopathologie , Humains , Tumeurs du poumon/traitement médicamenteux , Lymphome B de la zone marginale/traitement médicamenteux , Mâle , Adulte d'âge moyen
13.
Kyobu Geka ; 61(9): 765-7, 2008 Aug.
Article de Japonais | MEDLINE | ID: mdl-18697457

RÉSUMÉ

Small bowel metastasis from lung cancer is rare. We present 2 cases of small bowel metastasis from lung cancer. A 69-year-old man with postoperative lung cancer was admitted to our hospital because of the development of anemia secondary to melena A 56-year-old man with postoperative lung cancer was admitted to our hospital because of weight loss and fever. Both patients were operated on with suspicion of small intestine tumor after some examinations. The metastatic tumors were found in the small intestines. Resection of metastasis to the small bowel of lung cancer is benefical for better prognosis.


Sujet(s)
Carcinome à petites cellules/anatomopathologie , Tumeurs de l'intestin/secondaire , Intestin grêle , Tumeurs du poumon/anatomopathologie , Sujet âgé , Humains , Mâle , Adulte d'âge moyen
14.
J Neuroendocrinol ; 19(6): 449-60, 2007 Jun.
Article de Anglais | MEDLINE | ID: mdl-17504439

RÉSUMÉ

The reproductive system, including pulsatile luteinising hormone (LH) secretion, is inhibited by deficits in energy availability and restored by energy surfeits. Plasma LH, insulin, leptin, ghrelin, glucose, ketone body, and nonesterified fatty acid concentrations were measured in ovariectomised, food-restricted ewes before and after return to ad libitum feeding to determine the factors that change in time to account for the restoration of pulsatile LH secretion. At 07.00 h, blood was sampled every 10 min for 5 h from ovariectomised, hypogonadotrophic, chronically food-restricted and ad libitum-fed ewes (Fed). At 12.00 h, four of the food-restricted sheep were given ad libitum access to food (Re-Fed), while three ewes continued to be food restricted (Restricted). Sampling continued for 5 h and resumed again on the mornings of days 2, 4, and 9. A pulse of LH was seen within 1 h of re-feeding in all Re-Fed ewes, and interpulse interval (IPI) was significantly shorter in Re-Fed compared to Restricted ewes and longer than in Fed ewes during the period after re-feeding. Re-Fed LH IPI was not restored to that of Fed ewes until sometime between days 4 and 9. The first pulse occurred within minutes, whereas restoration of IPI occurred after 4-8 days. Prior to the initial LH pulses seen in Re-Fed ewes, plasma ketone bodies first fell and then rose to levels significantly above those in Restricted ewes. Significant changes in circulating insulin, ghrelin, glucose, and total ketone body concentrations, daily food intake and lean body mass preceded restoration of Re-Fed LH IPI some time between days 4 and 9, but there were no significant changes in adiposity or circulating leptin concentrations, consistent with the hypothesis that LH pulses are reinitiated by changes in the availability of oxidisable metabolic fuels and possibly insulin, but not leptin concentrations.


Sujet(s)
Glycémie/métabolisme , Cycle oestral/métabolisme , Insuline/sang , Hormone lutéinisante/sang , État nutritionnel/physiologie , Adiposité/physiologie , Animaux , Métabolisme énergétique/physiologie , Acide gras libre/sang , Femelle , Privation alimentaire , Ghréline , Corps cétoniques/sang , Leptine/sang , Hormone lutéinisante/métabolisme , Hormones peptidiques/sang , Ovis
15.
J Endocrinol ; 189(1): 67-75, 2006 Apr.
Article de Anglais | MEDLINE | ID: mdl-16614382

RÉSUMÉ

The purpose of this study was to investigate the effects of physiologic levels of ghrelin on insulin secretion and insulin sensitivity (glucose disposal) in scheduled fed-sheep, using the hyperglycemic clamp and hyperinsulinemic euglycemic clamp respectively. Twelve castrated Suffolk rams (69.8 +/- 0.6 kg) were conditioned to be fed alfalfa hay cubes (2% of body weight) once a day. Three hours after the feeding, synthetic ovine ghrelin was intravenously administered to the animals at a rate of 0.025 and 0.05 mug/kg body weight (BW) per min for 3 h. Concomitantly, the hyperglycemic clamp or the hyperinsulinemic euglycemic clamp was carried out. In the hyperglycemic clamp, a target glucose concentration was clamped at 100 mg/100 ml above the initial level. In the hyperinsulinemic euglycemic clamp, insulin was intravenously administered to the animals for 3 h at a rate of 2 mU/kg BW per min. Basal glucose concentrations (44+/- 1 mg/dl) were maintained by variably infusing 100 mg/dl glucose solution. In both clamps, plasma ghrelin concentrations were dose-dependently elevated and maintained at a constant level within the physiologic range. Ghrelin infusions induced a significant (ANOVA; P < 0.01) increase in plasma GH concentrations. In the hyperglycemic clamp, plasma insulin levels were increased by glucose infusion and were significantly (P < 0.05) greater in ghrelin-infused animals. In the hyperinsulinemic euglycemic clamp, glucose infusion rate, an index of insulin sensitivity, was not affected by ghrelin infusion. In conclusion, the present study has demonstrated for the first time that ghrelin enhances glucose-induced insulin secretion in the ruminant animal.


Sujet(s)
Aliment pour animaux , Glucose/métabolisme , Insuline/métabolisme , Hormones peptidiques/physiologie , Ovis/physiologie , Animaux , Glycémie/analyse , Castration , Relation dose-effet des médicaments , Ghréline , Glucose/effets indésirables , Technique du clamp glycémique/méthodes , Hormone de croissance/sang , Perfusions veineuses , Insuline/administration et posologie , Insuline/sang , Mâle , Medicago sativa/physiologie , Hormones peptidiques/administration et posologie , Hormones peptidiques/sang
16.
J Neuroendocrinol ; 17(6): 331-40, 2005 Jun.
Article de Anglais | MEDLINE | ID: mdl-15929739

RÉSUMÉ

Changes in leptin and ghrelin levels occur with alterations in adiposity, but signalling may be affected by levels of the relevant receptors. We measured expression of the leptin receptor (Ob-Rb) and the ghrelin/growth hormone releasing peptide receptor (GHS-R) in the arcuate nucleus of sheep held at either high or low levels of adiposity. Plasma growth hormone (GH) levels were lower in Fat animals and higher in Lean animals. Plasma insulin and leptin levels were higher in Fat animals and lower in Lean animals. Frozen hypothalamic sections of arcuate nucleus were extracted and mRNA levels measured for mRNA for Ob-Rb and GHS-R. Gene expression for both Ob-Rb and GHS-R was higher in Lean animals than in Fat animals, with no difference in expression between Fat and Normal animals. A second group of animals (n = 4 per group) was used for double-labelling immunohistochemistry to determine whether the increase in Ob-Rb gene expression was translated into Ob-Rb protein and to ascertain whether this effect is localised to the cells of the arcuate nucleus that produce either neuropeptide Y (NPY) and/or pro-opiomelanocortin-derived peptides. Lean animals displayed a 255% increase in immunoreactive NPY cells (P < 0.005), a 167% increase in cells with Ob-Rb (P < 0.037) protein and a 344% increase in cells that were staining for both NPY and Ob-Rb (P < 0.02). There was no difference between the Normal and Lean animals in the number of cells that were detected with an adrenocorticotrophic hormone (ACTH) antibody or the number of ACTH-immunoreactive cells that also stained for Ob-Rb. Finally, we measured plasma ghrelin levels in Normal, Fat and Lean ewes (n = 4/group); levels were higher (P < 0.05) in Fat animals than in Lean animals. We conclude that lowering body weight leads to increased expression of Ob-Rb, ghrelin/GHS-R expression and proportion of NPY cells that express Ob-Rb in the arcuate nucleus. This may be an adaptive mechanism to increase responsivity to both leptin and ghrelin.


Sujet(s)
Tissu adipeux/physiologie , Noyau arqué de l'hypothalamus/physiologie , Poids/physiologie , Récepteurs de surface cellulaire/génétique , Récepteurs couplés aux protéines G/génétique , Hormone corticotrope/métabolisme , Animaux , Ration calorique/physiologie , Femelle , Expression des gènes/physiologie , Ghréline , Immunohistochimie , Neuropeptide Y/métabolisme , Hormones peptidiques/sang , Pro-opiomélanocortine/métabolisme , Récepteurs de surface cellulaire/métabolisme , Récepteurs couplés aux protéines G/métabolisme , Récepteurs à la ghréline , Récepteurs à la leptine , Ovis
17.
Anim Reprod Sci ; 82-83: 183-94, 2004 Jul.
Article de Anglais | MEDLINE | ID: mdl-15271452

RÉSUMÉ

Ghrelin, a novel acylated peptide, is the endogenous ligand for growth hormone secretagogue (GHS) receptor. Ghrelin is produced mainly in the oxyntic glands of the stomach, but also produced in the intestines, kidneys, hypothalamus and pituitary gland. Circulating ghrelin levels have been shown to rise before a meal and fall afterwards, suggesting that anticipation of a meal may stimulate secretion. In some species, ghrelin administration has been shown to stimulate growth hormone (GH) secretion, and to cause weight gain by increasing food intake and reducing metabolic utilization of fat. Furthermore, intracerebroventricular and intravascular administration of ghrelin increases gastric acid output in a dose-dependent manner. Thus, ghrelin may play an important role in controlling feeding behavior and energy homeostasis. We have investigated the role of ghrelin in the control of feeding and neuroendocrine function in ruminants using sheep as an experimental model. This mini review describes mechanisms regulating ghrelin secretion at feeding time, and also focuses on the neuroendocrine functions of ghrelin.


Sujet(s)
Consommation alimentaire/physiologie , Système neuroendocrinien/physiologie , Hormones peptidiques/physiologie , Ovis/physiologie , Animaux , Rythme circadien , Jeûne , Aliments , Ghréline , Hormone de croissance/métabolisme , Hormones peptidiques/administration et posologie , Hormones peptidiques/métabolisme
18.
J Endocrinol ; 180(2): 283-6, 2004 Feb.
Article de Anglais | MEDLINE | ID: mdl-14765980

RÉSUMÉ

Leptin suppresses food intake and increases energy expenditure in the hypothalamus. Rats consume most of their daily food intake during the dark phase of the diurnal cycle. Lactating rats have increased food intake, but the involvement of leptin in the regulation of food intake in this physiological condition is not well understood. The present experiment was carried out to determine the circadian pattern of leptin concentrations in plasma and cerebrospinal fluid (CSF) in relation to the feeding behavior of non-lactating and lactating rats. Female rats were maintained on a controlled lighting schedule (lights on between 0600 and 1800 h) and the food intake of lactating rats was two- or threefold higher than that of non-lactating rats. In both groups, food intake was three times greater in the dark phase (P<0.01) compared with the light phase. The plasma concentrations of leptin were lower (P<0.01) in lactating rats than non-lactating rats in both light and dark phases, but there were no differences in plasma leptin levels between light and dark phases. In contrast, and in both groups, the leptin concentrations in CSF were lower (P<0.01) in the dark phase than in the light phase. Leptin levels in CSF were lower (P<0.01) in lactating rats than in non-lactating rats. We conclude that a diurnal pattern of leptin levels within the brain (but not in plasma) reflects characteristics of feeding behavior in lactating and non-lactating rats.


Sujet(s)
Rythme circadien , Consommation alimentaire/physiologie , Lactation/physiologie , Leptine/liquide cérébrospinal , Animaux , Métabolisme énergétique , Femelle , Leptine/sang , Rats , Rat Wistar
19.
Article de Anglais | MEDLINE | ID: mdl-12547262

RÉSUMÉ

Leptin has been shown to regulate feed intake and energy expenditure. Insulin stimulates leptin secretion in rodents, but its action on leptin secretion is still obscure in ruminants. If insulin stimulates leptin secretion in ruminants, circulating leptin concentrations may change during exposure to cold, because of fluctuating insulin secretion and action in the cold environment. The present experiment was designed to determine whether feeding or exogenous administration of insulin affects circulating leptin levels in sheep exposed to thermoneutral and cold environments. Suffolk rams that were shorn and fed a diet once daily were subjected to a thermoneutral (20 degrees C) or cold (0 degrees C) environment for at least 1 week. Overall mean concentrations of plasma leptin in the feeding experiment were lower (P<0.05) in the cold environment than in the thermoneutral environment. Plasma leptin levels remained relatively unchanged after feeding in both environments, though plasma insulin response to feeding in both environments increased (P<0.01). The euglycemic clamps (insulin infusion rate: 4 mUkgBW(-1)min(-1) for 2 h) increased (P<0.01) circulating leptin concentrations in the thermoneutral, but not in the cold environment. These results suggest that lower circulating leptin levels in ruminants exposed to the cold environment could be partly due to the depressed insulin action on leptin secretion.


Sujet(s)
Basse température , Consommation alimentaire/physiologie , Insuline/pharmacologie , Leptine/sang , Ovis/sang , Animaux , Glycémie/analyse , Technique du clamp glycémique , Pompes à perfusion , Insuline/administration et posologie , Insuline/sang , Mâle , Concentration osmolaire , Température
20.
Biochem Biophys Res Commun ; 295(2): 255-60, 2002 Jul 12.
Article de Anglais | MEDLINE | ID: mdl-12150940

RÉSUMÉ

Ghrelin, a gastric-derived peptide, has recently been identified as an endogenous natural ligand for the growth hormone (GH) secretagogue receptor. However, secretory characteristics of ghrelin are still obscure in ruminants. To investigate the diurnal rhythm in ghrelin secretion and its relationship to GH secretion, plasma ghrelin and GH concentrations were determined in Suffolk rams fed with a roughage diet once daily (Experiment 1). Abrupt increases (P<0.05) in plasma ghrelin occurred just before a meal-feeding compared with that at 1h before feeding, then rapidly fell with a minimum during the feeding. A pulsatile surge (P<0.01) in plasma GH concentrations, which seemed to follow a single surge in plasma ghrelin, was observed during the feeding. In Experiment 2, plasma ghrelin and GH were determined in sheep subjected to a pseudo-feeding of 2h to determine whether feed ingestion itself influences ghrelin and GH secretions. Compared with those at 1h before feeding, a tendency of increases (P<0.1) in plasma ghrelin and significant increases (P<0.05) in GH occurred just before and during a pseudo-feeding, respectively. Plasma ghrelin temporally declined within 1h after the start of the pseudo-feeding, and increased again and maintained higher levels during the last period of the pseudo-feeding. These results suggest that the transient surge of ghrelin secretion just before a scheduled meal feeding would not be due to the ingestion of feed, and that a pulsatile increase in plasma GH during the actual- or pseudo-feeding could be induced by the transient ghrelin surge.


Sujet(s)
Consommation alimentaire , Hormones peptidiques , Peptides/sang , Animaux , Rythme circadien , Technique d'immunofluorescence , Ghréline , Hormone de croissance/sang , Mâle , Ovis
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