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At least 919 records · Page 51Linked to original sources
PubMed1996

Endogenous opioids may modulate the activity of the hypothalamus-pituitary-adrenocortical axis in domestic fowl.

The activity of the hypothalamus-pituitary-adrenocortical (HPA) axis is under complex neuronal, hormonal and peptidergic control. In order to determine the role of the endogenous opioids in the modulation of the HPA axis in hens we have examined the changes of the plasma levels of Met-enkephalin, alpha-neo-endorphin, catecholamines and corticosterone during rest, stress (30 min of overcrowding) and after naltrexone pretreatment. Short overcrowding induced an increase of all parameters, but the time of response and duration of elevation was different. Plasma Met-enkephalin showed a biphasic response: decrease followed by increase at the end of stress. Catecholamines and corticosterone peaked at 30 min of overcrowding and the highest level of alpha-neo-endorphin has been noticed at 20 min after the experiment was started. Naltrexone (2 mg/kg b.w., i.v) diminished the responses to stress of all parameters and did not change their basal levels, except for corticosterone. These results indicate that the endogenous opioids may take part in the mediation of HPA activity in hens during resting and stressful situations.

Animals↗
PubMed1998

Evidence of the existence of alpha 1B-adrenoceptors on hepatocytes of domestic fowl (Gallus domesticus).

In liver cell membranes of laying hens alpha 1-adrenergic receptors were characterized using 3H-prazosin. Specific binding was saturable and indicative of a single class of high-affinity binding sites with a KD of 0.40 +/- 16 nM and a Bmax of 390 +/- 38 fmol/mg membrane protein. Preincubation of membranes with chlorethylclonidine significantly diminished the binding of 3H-prazosin (Bmax = 99 +/- 14 fmol/mg membrane protein). Furthermore, competition experiments revealed a rank order of prazosin >> phentolamine = oxymetazoline >> WB 4101, with Ki values of 0.71 +/- 0.62, 20 +/- 6, 32 +/- 13, and 119 +/- 48 nM, respectively. These results suggest the existence of alpha 1B-adrenergic receptors in hen liver cell membranes.

Animals↗
PubMed1989

Ivermectin as a bird anthelmintic--trials with naturally infected domestic fowl.

To evaluate the use of ivermectin as a bird anthelmintic, 29 White Leghorn hens naturally infected with Ascaridia spp., Heterakis spp. and Capillaria spp. were treated with 0.2, 2 or 6 mg/kg intramuscularly or 0.2 or 0.8 mg/kg orally. Faecal samples were collected before treatment and at autopsy, 2, 6, or 16 days after treatment, when the intestines were also examined for helminths. None of the treatments gave satisfactory anthelmintic results.

Animals↗
PubMedDate not supplied

Outbreak of mycotic tracheitis in domestic fowl.

An outbreak of mycotic tracheitis was observed in 8000 2-month-old, female White Leghorn birds. The birds were showing difficult respiration and there was mortality of 7-8 birds daily in the flock. On post-mortem examination of the affected birds, the trachea was found to be occluded with a white caseous mass. Microscopically hyphae were found invading the tracheal epithelium, cartilage and serosal layer along with infiltration of macrophages and lymphocytes. Aspergillus fumigatus was isolated in pure culture from the trachea. The birds responded to oral copper sulphate treatment. The ubiquitous occurrence of the organism and the conditions of the harvesting season have been found to be responsible for the outbreak of the disease.

Animals↗
PubMed1998

Electrical characteristics and responses to jejunal distension of neurons in Remak's juxta-jejunal ganglia of the domestic fowl.

1. Remak's nerve is a ganglionated nerve trunk found only in birds that runs parallel to the gut from the duodenal-jejunal junction to the cloaca. We report the first electrophysiological characterization of these neurons and their responses to gut distension. 2. A segment of chicken jejunum with attached Remak's nerve was pinned in an electrophysiological chamber. Neurons in Remak's ganglia were impaled with microelectrodes. The adjacent segment of gut was distended with fluid. 3. One hundred and thirty neurons were characterized into three electrophysiological classes: (i) tonic neurons (74%) fired action potentials spontaneously (frequency 3.5 Hz) and continuously (up to 40 Hz) throughout a depolarizing current pulse; (ii) AD neurons (22%) fired a brief burst of action potentials (1-10), which were followed by a prolonged after-depolarization (AD) of duration 2.8 +/- 0.3 s; and (iii) phasic neurons (4%) fired an initial burst of action potentials followed by an after-hyperpolarization (duration, 520.0 +/- 32.0 ms). Tetrodotoxin (1 microM) abolished action potentials in tonic and AD neurons as well as the after-depolarization. 4. Spontaneous fast excitatory postsynaptic potentials (FEPSPs) occurred in all classes of neurons; they were not observed, however, in ganglia isolated from the jejunum. 5. Intracellular injection of biocytin revealed that neurons could be characterized into four morphological classes. Tonic neurons, which had long and extensive dendritic trees, were Remak's Type I, II and IV neurons. AD neurons also comprised Remak's type II neurons. Phasic neurons were Remak's Type III neurons. Most neurons had axons that projected orally along Remak's nerve. 6. Distension of the jejunum evoked FEPSPs and action potentials in tonic neurons, and repetitive bursts of action potentials (1-4) followed by an after-depolarization in AD neurons. All responses to distension were blocked by hexamethonium (300 microM) and tetrodotoxin (1 microM). 7. In conclusion, neurons in Remak's juxta-jejunal nerve appear to regulate gut motility. Three distinct electrophysiological classes of neurons were observed, all of which appear to be activated by distension sensitive cholinergic intestinofugal neurons in the jejunum.

Action Potentials↗
PubMed1970

The concentration of catecholamines in the brain of the domestic fowl (Gallus domesticus).

1. The concentrations of adrenaline and noradrenaline in the brains of chickens (Gallus domesticus) have been determined using two different methods of fluorimetric analysis.2. The concentrations of adrenaline, noradrenaline and also dopamine were found to increase with age, as did the relative amount of adrenaline present in the chicken brain.3. It was observed that the differential assay of adrenaline by the trihydroxyindole method often underestimated the amount of adrenaline present.

Age Factors↗
PubMed1986

Effect of some metal compounds on the Ca2+ binding and Ca2+-Mg2+-ATPase activity of eggshell gland mucosa homogenate from the domestic fowl.

Some metal ions, e.g. Hg2+, Cd2+ and Al3+, can have the effects as ecotoxicological agents, of causing eggshell thinning and breakage in birds. In a homogenate of the Ca2+-secreting part of the eggshell gland mucosa, a study was made of the influence of Hg2+, Cd2+, Cu2+, Pb2+, methyl-Hg+, Zn2+, V3+, Al3+ and Ni2+ in different concentrations on the rate of ATP-dependent 10(-4) M Ca2+ binding. All compounds had an inhibitory action. The most potent metal (Hg2+) produced 50% inhibition (IC50) at 1.1 X 10(-6) M, whereas this value for the least potent compound (Ni2+) was 9 X 10(-4) M. The specific Ca2+-Mg2+-ATPase activity was also inhibited by the tested metal ions. In all cases except methyl-Hg+ the IC50 for this activity was lower than that for Ca2+ binding. The most potent ion in this respect was Cd2+, with an IC50 of 8 X 10(-8) M, and the least potent was methyl-Hg+, with an IC50 of 1.4 X 10(-3) M. Pb2+ and Cd2+ in a concentration range of 10(-5)-10(-4) stimulated the Mg2+-ATPase activity, however, to almost the same extent as 10(-4) M Ca2+. A possible explanation for this effect is that these ions may have an affinity for sites of Ca2+ binding of the polypeptide calmodulin and thereby influence the Ca2+ metabolism of the shell gland mucosa.

Animals↗