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At least 1,117 records · Page 62Linked to original sources
PubMed1988

Diminution of pulsatile growth hormone secretion in the domestic fowl (Gallus domesticus): evidence of sexual dimorphism.

Temporal plasma GH secretory patterns were measured in cannulated male and female meat-type chickens of two commercial strains at 17, 38 and 60 days of age. Pulse height, amplitude and baseline values were similar in both male and female chickens at 17 days of age, with high amplitude and low baseline values. However, by 38 days of age pulsatile GH secretion was not detectable in females, whereas males exhibited a continued pulsatile secretory pattern similar to that at 17 days of age. Pulsatile GH secretion was not evident in either males or females at 60 days of age. These results clearly demonstrate a sexually dimorphic ontogeny of GH secretion in meat-type chickens.

Aging↗
PubMed1989

Insulin-like growth factor-I binding proteins in serum from the domestic fowl.

This investigation describes the presence of insulin-like growth factor-I (IGF-I) binding proteins in chicken serum. Whole blood was collected from broiler chickens of 7-9 weeks of age and analysed for binding proteins after gel permeation chromatography under both neutral and acidic conditions, and by polyacrylamide gel electrophoresis in the presence of 12.5% sodium dodecyl sulphate (SDS-PAGE). When serum was chromatographed under neutral conditions, about 70% of the IGF-I immunoreactivity was associated with a large protein complex (Mr = 150,000) and 20-25% was associated with an intermediate-sized protein complex (Mr = 45,000). Up to 6% of the serum IGF-I immunoreactivity was eluted in a fraction which corresponded to an Mr of about 7500 and was presumably free IGF-I. Chromatography under acidic conditions dissociated the IGF-I/protein complexes and revealed the presence of an acid-stable binding protein (Mr = 50,000-60,000). After analysis of serum by SDS-PAGE, three monomeric IGF-I binding proteins (Mr = 28,800, 33,200 and 40,700) were detected. The largest monomer (Mr = 40,700) is probably the binding protein component of the intermediate-sized IGF-I/protein complex. The relationship between the other monomers and both the large IGF-I/protein complex and the acid-stable binding protein is not known. Although the pattern of binding proteins in chicken serum is similar to that observed in mammals, a major difference is the presence of up to 6% of the serum IGF-I immunoreactivity in an unbound form.

Animals↗
PubMed1989

Maturational changes in the LH response of domestic fowl to synthetic chicken LHRH-I and -II.

Treatment of chickens at different stages of sexual development with a single i.v. injection of synthetic chicken LHRH (cLHRH)-I or -II stimulated a rise in the plasma concentration of LH within 1 min. The activity of cLHRH-II was 1.3- to 2.7-fold greater than that of cLHRH-I in sexually immature cockerels and hens as determined by the changes in the plasma concentration of LH during the 5 or 10 min after injection. This could be attributed to both a greater effectiveness of cLHRH-II to stimulate LH release and to a more prolonged action. Thus, LH concentrations in plasma were maximal within 1-2 min of injection of all doses of cLHRH-I but within 2-5 min of injection at the higher doses of cLHRH-II. The responsiveness of the pituitary gland to cLHRH-I and -II was substantially greater in the sexually immature cockerel than in the hen and diminished during sexual development of the hen. Coincident with the onset of egg laying, the characteristics of the LH response to cLHRH-II changed to consist of an initial rise during the first 2 min, followed by a more sustained increase with LH concentrations still rising 10 min after injection. In contrast, after injection with cLHRH-I, plasma concentrations of LH rose to a peak at 2 min and thereafter declined gradually. Treatment of the sexually immature hen with oestradiol, progesterone or a combination of both steroids did not enable the expression of a laying hen-type response to the injection of cLHRH-II.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Central action of thyrotrophin-releasing hormone on growth hormone secretion in domestic fowl.

Peripheral plasma concentrations of GH in adult chickens were increased, in a dose-related manner, between 5 and 30 min after the intracerebroventricular (i.c.v.) injection of 0.1 or 10 micrograms TRH. In contrast, i.v. administration of comparable doses of TRH had no significant effect on circulating GH concentrations. [3H]3-methyl-histidine2-TRH [( 3H]Me-TRH) was located in the pituitary gland and peripheral plasma within 5 min of its i.c.v. administration, although in amounts that were unlikely to affect directly pituitary function. [3H]Me-TRH rapidly accumulated in the hypothalamus following its i.c.v. administration (but not after i.v. injection), and the central effect of TRH on GH secretion in birds is therefore likely to be induced by effects at hypothalamic sites.

Animals↗
PubMed2002

Ghrelin: a hypothalamic GH-releasing factor in domestic fowl (Gallus domesticus).

Ghrelin, a recently discovered peptide in the mammalian hypothalamus and gastrointestinal tract is thought to be the endogenous ligand for the GH secretagogue (GHS) receptor and it stimulates GH release in rats and humans. The possibility that ghrelin is present in birds was therefore assessed, since a GHS receptor is present in the chicken pituitary gland. Although immunoreactive ghrelin is readily detectable in the rat stomach and ileum, ghrelin immunoreactivity could not be detected in the chicken proventriculus, stomach, ileum or colon, whereas somatostatin immunoreactivity, in contrast and as expected, was readily detectable in the chicken gastrointestinal tract. Ghrelin immunoreactivity was, however, present in the chicken hypothalamus, although not in the arcuate (infundibular) nucleus, as in rats. Discrete parvocellular cells and neuronal fibers with ghrelin immunoreactivity were present in the anterior medial hypothalamus. This immunoreactivity was specific and completely abolished following the preabsorption of the antibody with an excess of human ghrelin. Ghrelin immunoreactivity was also present in clusters of large ovoid magnocellular cells in the nucleus magnocellularis preopticus pars medialis, nucleus magnocellularis preopticus supraopticus and in the chiasmaopticus. Immunoreactivity for ghrelin was restricted to the cytoplasm of the perikarya and their axonal sprouts. Immunoreactivity for ghrelin was not seen in any other hypothalamic nuclei. In a preliminary experiment, circulating GH concentrations in conscious immature chicks were promptly increased following bolus i.v. administration of human ghrelin. The increase in GH concentration (approximately three times that in the controls) was comparable with that induced by the same dose (10 microg/kg) of human GH-releasing hormone, although less than that (approximately sixfold) induced by thyrotropin-releasing hormone. These results demonstrate the presence of a ghrelin-like protein in the chicken hypothalamus and suggest that it participates in the regulation of GH secretion in birds.

Animals↗
PubMed2003

Ghrelin-induced GH secretion in domestic fowl in vivo and in vitro.

Although avian and mammalian species differ significantly in their regulation of GH secretion, preliminary studies have demonstrated in vivo GH responses to ghrelin in chickens, as in mammals. However, the relative potency of ghrelin as a GH-releasing hormone (GHRH) in birds is uncertain, as is its site of action. The intravenous administration of human ghrelin to immature chickens promptly increased the circulating GH concentration (within 10 min), although this was transitory and was only maintained for 20 min. This GH response was dose-related with an EC50 of approximately 3.0 microg/kg, comparable with the reported potency of human GHRH in chickens. When incubated with dispersed pituitary cells, human ghrelin induced dose-dependent GH release over a range of 10(-6) to 10(-9) M, with an EC50 of 7.0 x 10(-8) M, comparable with that induced by human GHRH (EC50 6.0 x 10(-8) M), although it was less effective at doses of 10(-6) to 10(-8) M. This was due to direct effects on pituitary somatotrophs, since human ghrelin increased GH release (determined by the reverse hemolytic plaque assay) from individual pituitary cells. The incubation of these cells with human ghrelin induced a dose-dependent increase in the numbers of somatotrophs secreting GH and in the amount of GH released by each cell. In summary, these results demonstrated that ghrelin is a dose-related GH-releasing factor in chickens with a potency comparable with that induced by human GHRH. The GH-releasing action of ghrelin is due, at least in part, to stimulatory actions on the numbers of somatotrophs induced to release GH and upon the amount of GH released from individual somatotrophs.

Animals↗
PubMed1994

Intensive production units and welfare: domestic fowl.

Major specialisation and intensification of the poultry industry in recent years have led to widespread public concern regarding the welfare of the animals involved. The debate originated some 25 years ago in Western Europe, resulting in regulations at both the national and European Union (Community) level. Animal welfare is ensured when the individual animal is coping successfully with the environment and is free from pain (e.g. due to injury or disease). The welfare of an animal is jeopardized when its regulatory action, in relation to relevant internal and external factors, is impossible or chronically hampered. Ample information is now available on housing requirements with regard to welfare. For poultry, these requirements relate to space, laying nests, litter and perches. The welfare of laying hens is compromised in highly intensive systems such as battery cages. Alternative housing systems, taking into account the housing requirements mentioned above, may considerably improve the welfare of these birds. Welfare problems in broilers and broiler breeders may best be alleviated by alternative selection programmes which take into account parameters related not only to economic efficiency but also to health and welfare.

Animal Husbandry↗
PubMed1986

Amino-acid metabolism enzyme activities in the liver, intestine and yolk sac membrane of developing domestic fowl.

To contribute to our understanding of nitrogen metabolism in the developing chick we have studied in liver, intestine and yolk sac membrane the ontogeny of both aspartate- and alanine transaminases, glutamate dehydrogenase, adenylate deaminase, glutamine synthetase and xanthine dehydrogenase activities. Liver enzyme activities were much higher than those of the same enzymes in intestine and yolk sac membrane, the latter having the lowest activities. In the liver, both alanine transaminase and glutamate dehydrogenase increased their activity just before hatching, xanthine dehydrogenase and glutamine synthetase develop their highest activity just after hatching, while aspartate transaminase and adenylate deaminase attained the highest levels just with adulthood. From the pattern of enzyme activity in yolk sac membrane and intestine it can be inferred that after hatching, the amino-acid metabolism in these tissues is considerably enhanced, with higher production of ammonia from amino acids, as indicated by the rise in adenylate deaminase, as well as increased potentiality in production of both alanine and glutamine. It can be concluded that hatching coincides with a deep change of pace in amino-acid metabolism in the organs studied fully comparable with that observed in Mammals at the end of lactation, with the difference that the adaptation to the new diet in the case of the chick is much more sudden than weaning is for the rat.

AMP Deaminase↗