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At least 721 records · Page 40Linked to original sources
PubMed1986

The effects of glucagon and insulin on plasma thyroid hormone levels in fed and fasted domestic fowls.

Glucagon injection (50 micrograms kg-1) produced a biphasic response in plasma thyroxine (T4) level in both fed and fasted chickens. An initial inhibition was followed by an increase to levels above control value. Glucagon reduced plasma triidothyronine (T3) possibly as a consequence of inhibition of peripheral monodeiodination. This inhibition persisted in fasted animals despite a glucagon induced hyperglycaemia. Insulin injection (4 IU kg-1) decreased plasma T4 concomitant with a profound hypoglycaemia. These effects were more pronounced in fasted birds. Insulin induced hypoglycaemia was associated with decreased plasma T3 probably as a consequence of reduced thyroidal T4 secretion and reduced peripheral monodeiodination. Glucagon and insulin may play direct or indirect roles in the regulation of thyroid hormone secretion and metabolism in the domestic fowl.

Animals↗
PubMed1986

Effect of starvation and protein-feeding on blood amino acid compartmentation of domestic fowl hatchlings.

The amino acid concentrations in plasma and blood cells of 5-day old domestic fowl hatchlings that received either standard feeding, protein-feeding or were starved have been determined. The effects of 5-day starvation or protein feeding did not alter significantly the combined amino acid concentration of blood plasma, but decreased blood cell levels. The patterns of individual amino acid changes observed in starvation or protein-feeding were similar in both groups when compared with those of controls. However, starvation-induced effects were actually more marked than those observed in protein-fed animals. The patterns of change with starvation of individual amino acids in the hatchling blood compartments were very different from those observed in mammals subjected to short or medium-term starvation. The mechanisms controlling circulating amino acid concentrations act in both situations studied to maintain the plasma amino acid concentrations despite marked changes in the availability of 2-amino nitrogen energy to the animal; changes in blood amino acid compartmentation buffering plasma amino acid availability.

Amino Acids↗
PubMed1986

Tissue glycogen and lactate handling by the developing domestic fowl.

The levels of glycogen and lactate in liver, intestine, yolk sac membrane and leg and breast muscle of domestic fowl from day 10 of "in ovo" development to day 5 after hatching compared with adults have been measured and compared with the circulating concentrations in blood of glucose and lactate. Glycogen stores in most tissues increased before hatching to attain a minimum around the eclosion and then increased to adult values in muscle and liver. Lactate maintained its plasma concentrations with higher effectiveness than plasma glucose, which increased steadily up to adult levels from hatching. The study of tissue vs plasma lactate concentration ratios suggests a general activation of lactate metabolism from hatching, coinciding with the ingestion of carbohydrate-based food. Both muscles studied, as well as intestine, seem to be net lactate producers; blood cells can speculatively be considered as lactate users and liver maintains its concentration of lactate very close to that plasma, suggesting a fast utilization of this material as well as liver being the main site for control of circulating lactate.

Aging↗
PubMed1986

Plasma iodothyronines in the domestic fowl: newly hatched to early adult stages, with special reference to reverse triiodothyronine (rT3).

Circulating concentrations of thyroxine (T4), triiodothyronine (T3) and reverse triiodothyronine (rT3) were measured in chicks before, during, and after hatching, up to 9 weeks of age. T4 decreased prior to hatching, rose after emergence, and was variable in the immature domestic fowl. T3 increased prior to emergence, decreased until 5 days after hatching, and increased again by 1 week of age, after which the levels declined. Plasma rT3 declined prior to hatching, remained low until 5 days after emergence, and then increased, again, to 0.14-0.19 ng/ml between 1-9 weeks of age.

Aging↗
PubMed1987

How closely do circulating blood glucose levels reflect feeding state in fowls?

1. Amounts of food eaten in 30 min, by fasted-refed immature hens, were not correlated with plasma glucose levels before feeding, or with increases in glucose after feeding. 2. When previously fasted birds were given 0, 5, 10, 15 or 20 g food to eat, their plasma glucose increased by similar amounts with 10, 15 and 20 g, by slightly less with 5 g, and hardly at all with 0 g. 3. When food was removed from free-feeding birds, their plasma glucose levels declined slightly in 2 hr and then remained steady. They declined markedly further overnight, but recovered to a level higher than before deprivation when 10 g food was provided. 4. Four hours darkness during normal daytime had no effect on plasma glucose in fasted-refed birds, but sight of food and presentation of an empty food pan caused slight increases in glucose in 24-hr fasted birds. 5. It is concluded that blood glucose in fowls fluctuates around several "typical" levels, but that there is also much variation between and within birds. Direct (absorbed) and indirect (thermogenic) consequences of feeding probably both contribute to fluctuations in glucose, and these seem more likely to influence regulation of food intake in the longer-term rather than the short-term.

Animals↗
PubMed1987

Somatostatin inhibition of growth hormone secretion in an adult bird: the domestic fowl.

1. The intravenous (i.v.) infusion of somatostatin (SRIF, 1.0 microgram/kg per min) promptly (within 5 min) reduced the growth hormone (GH) concentration in the plasma of conscious adult chickens. 2. The GH concentration progressively declined throughout a 60-min period of SRIF infusion, but was dramatically increased above pre-infusion levels within 5 min of SRIF withdrawal and maintained at an elevated level for at least 30 min afterwards. 3. Sodium pentobarbitone-anaesthesia lowered the basal GH concentration to levels comparable with those in conscious birds infused with SRIF. When administered to anaesthetized birds, exogenous SRIF was unable to further reduce the GH concentration and unable to induce 'rebound' GH release. 4. While thyrotropin releasing hormone (TRH, 10 micrograms/kg) increased the GH concentration in both conscious and anaesthetized birds, only the GH response in the anaesthetized birds was diminished by SRIF infusion. 5. Rebound GH secretion following the termination of SRIF infusion was observed in both conscious and anaesthetized birds injected with TRH. 6. These results demonstrate that SRIF can inhibit basal and TRH-stimulated GH secretion in adult domestic fowl and indicate that anaesthesia disrupts the normal control of GH releases.

Animals↗
PubMed1987

Anaerobic metabolism in fowl embryos during normal incubation.

Lactate concentration in blood, liver, yolk, amniotic and allantoic fluid and blood pyruvate was measured in embryos in the final week of incubation. Blood lactate was low up to day 18. The blood lactate/pyruvate ratio and liver lactate increased from day 19 until hatching. From day 14 to 19, lactate concentration in amniotic fluid remained constant, it increased 2-fold in yolk and 10-fold in allantoic fluid. There was only a 48% net accumulation of lactate in the three cavities. In conclusion, fowl embryos do not turn to anaerobic metabolism until the hatching process starts on day 19.

Allantois↗
PubMed1987

Plasma glucagon and energy substrate responses of domestic fowl to treadmill exercise.

Exercise-induced alterations in the concentrations of plasma glucagon-like immunoreactivity (GLI), plasma free fatty acids (FFA) and blood glucose and lactate were measured in separate groups of male and female domestic fowl. There were only small changes in blood glucose and lactate concentrations but plasma FFA and GLI rose by up to 450 and 200% respectively. There was evidence that the GLI response was stronger at higher exercise intensities. It is suggested that the mobilization of FFA for use as energy substrates by the working muscles may be stimulated by the enhanced secretion of glucagon.

Animals↗
PubMed1989

Effect of heat stress on plasma levels of arginine vasotocin and mesotocin in domestic fowl (Gallus domesticus).

1. The effect of an acute heat stress on plasma arginine vasotocin (AVT) and mesotocin (MT) levels were determined in non-heat-acclimated domestic fowl. 2. Heat increased (P less than 0.05) AVT and decreased MT (P less than 0.05) levels but had no affect on plasma osmolality. Changes in MT were correlated with body temperature (-0.40) and blood pCO2 (0.32). However, changes in AVT were not correlated with any physiological variable, including MT. 3. During thermoneutral recovery, with the exception of hematocrit which remained lower (P less than 0.05), all monitored variables returned to values which were not different (P greater than 0.05) from those observed prior to heat stress. 4. These results indicate that in non-heat-acclimated birds, acute heat stress elevated plasma AVT and suppressed the release of MT and that changes in these hormones occurred independent of any change in plasma osmolality.

Animals↗
PubMed1989

Effects of moderate intensity treadmill exercise on triglyceride production in the laying fowl.

1. Sustained aerobic exercise in domestic fowl has previously been shown to enhance lipid utilization by the skeletal muscles. The present study examined the possibility that such increased lipid oxidation in the laying female might lower the production of plasma triglycerides destined for transfer to the developing oocytes. 2. Following an intravenous injection of 25 muCi of 14C-labelled glycerol trioleate, the experimental birds performed 90 min of treadmill exercise at a work intensity approximately equivalent to 2.5 times the resting metabolic rate. 3. There was no evidence of either glycogen or triglyceride depletion in either the leg muscles or the viscera of the exercised birds. The specific activity of triglyceride TG-SRA found in the tissues was also the same in control and experimental birds. The time-course of the changes in plasma TG-SRA throughout the experimental period gave no indication that TG production had been affected by exercise. 4. It is concluded that the increased energy substrate demand arising from moderate-intensity, aerobic exercise is almost fully met by the liberation of fatty acids from adipose tissue TG stores, and has minimal impact on the hepatic manufacture of egg lipids.

Animals↗
PubMed1991

The effects of genetic selection for increased growth rate on mucosal and muscle weights in the different regions of the small intestine of the domestic fowl (Gallus domesticus).

1. The total organ weights and the constituent weights of mucosal and muscle tissues have been determined in the small intestines of three lines of domestic fowls subjected to different degrees of artificial genetic selection for rapid growth rates. 2. Effects of selection have been examined on the basis of wet and dry tissue weights in duodenum, jejunum and ileum from each line of birds. 3. Effects of selection have been compared on both absolute tissue weights and relative weights (i.e. expressed per kilogram body weight). 4. Selection for rapid growth rate is associated with increases in absolute weight and length of small intestine but marked reductions in relative weight and length. 5. In the fastest growing group of birds the major effect is a decrease in the relative mass of mucosa which is most pronounced in the more proximal regions of the small intestine. 6. These findings are discussed in relation to possible enhancement of intestinal digestive and absorptive efficiency in birds selected for improved growth rate and feed conversion. 7. The differences in tissue composition of the small intestine between lines and between regions of the intestine in the same line emphasise the difficulty in selecting an anatomical parameter upon which to base the in vitro and in vivo measurements of nutrient absorption in a number of established preparations.

Animals↗
PubMed1991

The time course in development of hypocalcemia and plasma lactate accumulation in mature and immature hyperthermic domestic fowl (Gallus domesticus).

1. During hyperthermia-induced thermal panting, there was a progressive development of alkalosis, hypocapnia, hypocalcemia and plasma lactate accumulation in both mature and immature domestic fowl. 2. The results of this study further demonstrate that hypocalcemia is a general consequence of respiratory alkalosis in animals. 3. The significant (P less than 0.05) regression analysis of plasma lactate vs arterial blood pH, suggest a relationship between these two variables. 4. Plasma lactate accumulation may therefore play an important role as an extrarenal buffering component in the normal defense against severe alkalosis.

Aging↗
PubMed1993

Thermogenic, thermoregulatory and activity effects of fenfluramine, a 5-hydroxytryptamine agonist, in immature domestic fowl (Gallus domesticus).

1. DL-Fenfluramine, a 5-hydroxytryptamine (5-HT) agonist, increases the metabolic rate of the adult domestic fowl and also stimulates heat loss mechanisms. Since thermogenic mechanisms vary qualitatively and quantitatively with age, this series of experiments was designed to measure the effects of fenfluramine on immature, growing, 'broiler' chickens. 2. The work was also designed to distinguish any direct effect of fenfluramine on respiratory quotient (RQ) from the indirect effects of reduced food intake. 3. Female commercial broilers were used (5-7 weeks old; 1.1-1.8 kg), at an ambient temperature of 25 degrees C and on a 14 hr light: 10 hr dark cycle. DL-Fenfluramine was injected intramuscularly at 80 mumol/kg body weight (20 mg/kg), in 0.5 ml of 9 g/l saline per kg bodyweight. 4. When the effects on heat production (H) of differences in food intake were eliminated by fasting, fenfluramine increased H by up to 20% within about 20 min. 5. RQ decreased four times more rapidly after fenfluramine injection than after the control treatment whether the birds were fed or fasted, reaching 0.70 in about 3 hr. 6. Wing-drooping and polypnea occurred within 10 min of injection. Maximal response was in 30 min to 1 hr for polypnea and 30 min to 2 hr for wing-drooping, depending on experimental procedure. Both responses ceased in 5-7 hr. 7. Physical activity was greatly reduced by fenfluramine, particularly in the first 4 hr. This effect occurred whether food was available or not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The relationship between duration of stimulus per day and the extent of hypertrophy of slow-tonic skeletal muscle in the fowl, Gallus gallus.

1. Passive stretch stimulus ranging from 30 min to 8 hr per day were studied on the slow twitch latissimus dorsi muscle (ALD) of the fowl for a 5-week period. 2. A significant increase in the mass of the ALD was observed in all daily durations of stretch stimulus applied. Nearly 50% of the mass increase that occurred with stretch of 8 hr per day was obtained from durations of stretch as short as 30 min per day. 3. Given that stretch is the equal of dynamic loading with respect to increasing muscle mass, it is concluded that stretch stimulation periods as short as 30 min per day may be just as effective as longer durations when hypertrophy is the desired result, such as following fracture, or muscle building in order to enhance athletic performance. 4. In fact it may be that longer durations of daily stimulus may be detrimental to the muscle as the functional capacity may be compromised.

Animals↗
PubMed1996

Myoelectric activity of the cecum in fed and fasted domestic fowl (Gallus sp.).

To study cecal motility and its relation to the fed and fasted condition in domestic fowl, we sutured 7 miniature electrodes onto the ceca and ileum of 4 roosters. After recovery from the surgery, the birds received recordings of myoelectric activity for a total of 169 h while fasted and for 28 h while in the fed state. We found that single or brief clusters of action potentials (APs) occurred in the cecal smooth muscle at mean frequencies of 10.8 to 25.0/h, with the fewest when the lumen contained little food (after fasting > 24 h). Virtually all APs propagated, whether orad (toward the ileocecocolic junction) or retrograde (toward the cecal tip), with retrograde activity significantly more frequent (P < 0.001). Propagation velocity was rapid, varying from 8 to 750 cm/min (mean = 106 cm/min), being slower when birds were in the fed state. Thus, fasting resulted in fewer and more rapid APs and more that propagated toward the cecal tip. Motor activity was well coordinated between ceca, both organs showing essentially simultaneous spike activity; 72% of APs occurred within 8.1 s of each other. No relationship between ileal and cecal activity was apparent. Prominent slow waves were recorded in the ceca (5 to 5.5/min), the same slow-wave frequency as in the ileum (small intestine). From the results obtained here and from earlier studies, we conclude that the single or brief clusters of APs represent contractions that produce mixing of the luminal contents; occasional periods of protracted APs represent evacuation of cecal contents.

Action Potentials↗
PubMed1984

Infrasound responses in the midbrain of the guinea fowl.

The electrophysiological audiogram of the Guinea fowl has been obtained using auditory evoked potentials from the MLD of unanesthetized birds. In restricted regions of MLD, phase-coupled responses to extreme low-frequency sinusoids (2-10 Hz) could be recorded at moderate intensities. The tonotopy of MLD extends continuously to the infrasound region at the rostrodorsal margin. Single-cell recording of infrasound responses show phase-locked firing of neurons with different phase delays for different cells.

Animals↗
PubMed1986

Vasotocin fibers in the mesencephalon and pons of the domestic fowl. An immunohistochemical study.

Immunohistochemical analysis of the extrahypothalamic distribution of vasotocin-like immunoreactive elements within the brainstem of the domestic fowl revealed several, topographically identifiable, mesencephalic and pontine target areas. In the considered regions numerous nerve endings were surrounding perikarya or large dendritic trunks. No extrahypothalamic immunopositive perikarya have been observed in normal birds.

Animals↗
PubMed1987

Projections of visceral and somatic primary afferents to the sacral spinal cord of the domestic fowl revealed by transganglionic transport of horseradish peroxidase.

The termination of visceral and somatic primary afferent fibers in the sacral spinal cord of the domestic fowl was studied using transganglionic transport of horseradish peroxidase. Nerve terminals of visceral afferent fibers were found in the lateral edge and base of the dorsal horn and in the dorsal gray commissure in close proximity to parasympathetic preganglionic neurons. Somatic afferents terminated in laminae 2 and 3. The results demonstrate that visceral and somatic afferent fibers in this avian species terminate in different areas of the dorsal horn.

Animals↗