Adrenal cortical activity in the domestic fowl, Gallus domesticus, following withdrawal of water or food.
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Adrenal Cortex↗
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The effects of eggshell porosity on blood-gas and acid-base status of domestic fowl embryos within eggs of the same weight.
Eggshell porosity affects the metabolism and growth of the developing embryo and is likely, therefore, to influence blood-gas and acid-base status. PO2 in the airspace and in blood from the allantoic vein, PCO2 in the airspace and in blood from the allantoic artery and allantoic vein, and pH of blood from the allantoic artery and vein are all affected by shell porosity. Low porosity eggshells result in an increased retention of carbon dioxide within the egg, in partial compensation for which an increase in the level of bicarbonate in the blood is predicted. It is concluded that some of the wide variation in blood physiology data between eggs at the same stage of incubation, which has been recorded in the scientific literature, is the result of variation in shell porosity between eggs.
Acid-Base Equilibrium↗
Plasma concentrations of arginine vasotocin, prolactin, aldosterone and corticosterone in relation to oviposition and dietary NaCl in the domestic fowl.
The osmolality and concentrations of Na, K, Cl and the hormones arginine vasotocin (AVT), prolactin, aldosterone and corticosterone were measured in plasma as functions of time in relation to oviposition, changing NaCl content of the diet, and feeding-inanition. AVT was significantly increased immediately after oviposition (but not during the hour before) with a calculated average value of 38.0 +/- 4.1 pg/ml at oviposition. A moderate increase in concentrations of prolactin and corticosterone were observed immediately after oviposition. Oviposition was not associated with detectable changes in plasma osmolality (and electrolyte concentrations) nor with the concentration of aldosterone. After a sudden change from a high NaCl diet to a low NaCl diet the plasma osmolality and concentrations of NaCl, AVT and prolactin reached new stable levels in 24 hr, whereas the plasma aldosterone concentration required more than 4 days to reach a steady level. After resalination plasma aldosterone was suppressed in less than 8 hr. Both osmolality and concentrations of AVT and prolactin showed transient overshoots during the first 24 hr. NaCl depletion resulted in a transient increase of corticosterone.
Aldosterone↗
Maturational changes in T4 to T3 conversion in domestic fowl.
The in vivo conversion of thyroxine (T4) to triiodothyronine (T3) has been determined in fed and 24 hr-fasted thyroidectomized cockerels at 4, 7, 13 and 23 weeks of age. The conversion of T4 to T3 in pubertal (13-week-old) and adult (22-week-old) cockerels was greater than that in immature (less than 7-week-old) chicks. The deprivation of food for 24 hr markedly reduced the rate of T4 to T3 conversion, especially in immature chicks. These maturational changes in T4 to T3 conversion may be related to differences in metabolic rate.
Aging↗
Somatostatin immunoneutralization affects plasma metabolite concentrations in the domestic fowl.
Young leghorn cockerels were injected with antiserum to somatostatin (anti-SRIF) and plasma glucose, free fatty acids and alpha-amino nitrogen concentrations determined. Plasma glucose concentrations increased rapidly after anti-SRIF and remained high for up to 2 hr. Two different antisera tested had hyperglycaemic activity. Plasma free fatty acids also increased rapidly after administration of the two different anti-SRIFs, and remained high for about 1 hr. Plasma alpha-amino nitrogen increased during the first 30 min after anti-SRIF, then declined to levels significantly lower than control by 1-2 hr after injection. Anaesthesia reduced plasma concentrations of glucose and alpha-amino nitrogen, and also reduced the changes of these metabolites following anti-SRIF. The results show the importance of endogenous somatostatin in the regulation of plasma metabolite concentrations.
Animals↗
Growth, protein synthesis and plasma concentrations of growth hormone, thyroxine and triiodothyronine in dwarf, control and growth-selected strains of broiler-type domestic fowl.
Body weight, tissue weight and plasma hormone concentrations were determined at 1, 3, 6, 12 and 21 weeks of age in two dwarf strains and one control strain of broiler chickens. Protein synthesis, accretion and degradation rates were determined in the control strain with age. Within each strain, plasma growth hormone (GH) concentrations were greater at 1 and 3 weeks of age and consequently decreased with age. Plasma GH concentrations were greater in the sex-linked dwarf chicken during pubescence and maturity (12 and 21 weeks) compared to the autosomal dwarf and control chickens. Circulating concentrations of 3,5,3' triiodothyronine (T3) were depressed by 70% in sex-linked dwarf birds compared to controls, while thyroxine concentrations did not differ at most time points. These findings support the suggestion that sex-linked dwarf chickens have reduced peripheral conversion of T4 to T3.
Aging↗
Some biological activities of recombinant DNA-derived growth hormone on plasma metabolite concentrations in domestic fowl.
The biological activity of recombinant-DNA-derived chicken growth hormone (rcGH) has been examined in young broiler cockerels, by determining its effects on plasma concentrations of glucose, free fatty acids and alpha-amino nitrogen. A single injection of rcGH increased plasma glucose, which remained high for several hours, whereas daily treatment with rcGH for 1 week had no effect on basal plasma glucose concentrations but blunted the glucose response to a further rcGH challenge. Plasma free fatty acids were also promptly increased following acute rcGH treatment, and chronic exposure to rcGH again attenuated this response. The effects of rcGH on plasma alpha-amino nitrogen were more variable. The stress of repeated blood sampling tended to reduce alpha-amino nitrogen, and after rcGH, an increase relative to vehicle-injected controls was seen in both acute and chronically-treated birds. These data suggest that rcGH has both hyperglycaemic and lipolytic activity in chickens, and may also increase amino acid availability.
Amines↗
Effect of hemorrhage on hepatic tissue blood flow in the domestic fowl (Gallus domesticus).
1. Thermal Pulse Decay (TPD) methodology was used to monitor hepatic tissue blood flow (hepatic perfusion) in anesthetized birds prior to and during hemorrhagic hypotension. 2. Hemorrhage was accomplished by periodic removal of blood through a carotid cannula. Reducing the estimated blood volume (BV) from 100 to less than 50% decreased hepatic perfusion from 4.36 +/- 0.7 to 1.88 +/- 0.7 ml/min/g. 3. Changes in hepatic perfusion during the experiment were related to mean arterial blood pressure (MABP) by the following linear regression equation: hepatic perfusion = -1.79 +/- 0.0807x (r2 = 0.57).
Animals↗
Relationships between renal hemodynamics and plasma levels of arginine vasotocin and mesotocin during hemorrhage in the domestic fowl (Gallus domesticus).
1. Renal tissue blood flow (renal perfusion) and plasma levels of arginine vasotocin (AVT) and mesotocin (MT) were measured in anesthetized chickens before and during hemorrhage. 2. Renal perfusion did not decrease (P less than 0.05) until nearly 50% of the blood volume had been removed. The decrease in renal perfusion was not related to arterial blood pressure but was concomitant with an increase (P less than 0.05) in plasma AVT levels. 3. Renal perfusion during hemorrhage was positively correlated with plasma MT levels by the regression equation: renal perfusion = 0.091 (MT)-1.1459 which was highly significant (P less than 0.001, r2 = 0.95). 4. The results of this study suggest that MT as well as AVT may participate in regulating blood flow in the avian kidney.
Animals↗
Activation of dynein adenosine triphosphatase and flagellar motility of demembranated spermatozoa by monovalent salts at 40 degrees C in the domestic fowl, Gallus domesticus.
1. At 40 degrees C, around the normal avian body temperature, demembranated fowl spermatozoa with no addition of monovalent chlorides were immotile. 2. Demembranated spermatozoa become motile at 40 degrees C when 0.1-0.5 M concentrations of NH4Cl, NaCl and KCl were added to the reactivation medium, with maximum motility occurring at 0.2-0.3 M in all cases. 3. The addition of NH4Cl, NaCl and KCl also stimulated the ATPase activity of crude dynein extract. In contrast, LiCl did not appreciably affect motility and ATPase activity. 4. These results showed that the flagellar dynein ATPase activity of fowl spermatozoa could be stimulated by the addition of certain monovalent chlorides, except LiCl, and demembranated spermatozoa might be motile at 40 degrees C.
Animals↗
Effects of temperature on the immobilization and the initiation of motility of spermatozoa in the male reproductive tract of the domestic fowl, Gallus domesticus.
1. The motility of undiluted fowl spermatozoa taken from testis, epididymis and ductus deferens was negligible at 40 degrees C, around the normal avian body temperature. 2. The immobilization was not permanent and motility was restored by decreasing the temperature to 30 degrees C or by suspending in a NaCl/TES buffer with 2 mM Ca2+, 2 mM HCO3- or 10% seminal plasma at 40 degrees C. 3. Demembranated spermatozoa taken from testis, epididymis and ductus deferens were also immotile at 40 degrees C. However, these spermatozoa were restored the motility at 30 degrees C except testicular spermatozoa. 4. These results suggest that the capacity of movement of fowl spermatozoa can be readily obtained from testis, but that these spermatozoa are immotile due to temperature-dependent immobilization in the male reproductive tract. 5. Furthermore, it is possible that changes in environmental temperature at ejaculation are one of the important exogenous physiological factors of the initiation of fowl sperm motility.
Animals↗
Effects of genetic selection on growth rate and intestinal structure in the domestic fowl (Gallus domesticus).
1. Pieces of small intestine taken from chickens subjected previously to continuous selection, relaxed selection or no selection for rapid growth were used to estimate villus surface area and microvillus development to determine what effects genetic selection might have on factors controlling intestinal function. 2. Crypt size and the rates at which enterocytes migrated out of crypts were also measured, after injection of tritiated thymidine, to determine the time course of microvillus elongation. 3. Differences in growth rates measured between highly selected, relaxed selected or unselected birds were found to be correlated with parallel changes in villus surface area. Selection for growth did not change the density, dimensions or pattern of development of enterocyte microvilli. Microvilli did, however, produce a maximal 20-fold increase in villus surface area under all conditions. 4. Crypt size and enterocyte migration rates did not vary significantly between tissue taken from unselected and relaxed selected chickens. Tissue taken from highly selected birds had a crypt size and enterocyte migration rate 40% higher than values found for the other two groups of chickens. 5. The possibility that early genetic selection increased growth potential by uncoupling diet-induced changes on crypt hyperplasia from secondary effects on villus structure, and that later selection increased growth potential by increasing appetite, is discussed.
Animals↗
Thermogenic, thermolytic and body temperature effects of fenfluramine, a 5-hydroxytryptamine agonist, in the domestic fowl (Gallus domesticus).
1. Intramuscular injection of the 5-HT agonist DL-fenfluramine increased the metabolic rate of mature cockerels by about 25% over the following 22 hr. The acute effect, over the 3 hr following injection, attained 40% at 10 degrees C, 35% at 20 degrees C and 25% at 32 degrees C. 2. Heat loss mechanisms (peripheral vasodilatation, postural change and panting) were also stimulated, to an extent which varied with ambient temperature. 3. Food intake, respiratory quotient and locomotor activity were significantly reduced by fenfluramine injection. 4. The opposing effects on heat production and heat loss had an influence on deep-body temperature which varied from a reduction of 0.5 degrees C at 10 degrees C ambient to an increase of about 0.5 degrees C at 32 degrees C. 5. The 5-HT blocker, methysergide, prevented the effects of fenfluramine on both heat production and heat loss for about 5 hr after injection. 6. The autonomic ganglion blocker, hexamethonium chloride, reduced the thermogenic but not the heat-loss effects of fenfluramine. 7. The results suggest that DL-fenfluramine has centrally-occurring but independent effects on heat production and a number of heat loss effectors, and that the heat production effect is mediated by the autonomic nervous system. The effect of fenfluramine on deep-body temperature appears to result from an altered equilibrium between heat production and heat loss.
Animals↗
Embryonic heart rate of the domestic fowl (Gallus domesticus) in a quasiequilibrium state of altered ambient temperatures.
1. The heart rates (fH) of 12-day-old embryos (young), 16- and 18-day-old embryos (late) and of 20-day-old embryos (externally pipped eggs, EP) were measured noninvasively at a temperature of 38 degrees C and after a 5 hr exposure to an ambient temperature (Ta) within the range 34-46 degrees C. 2. All embryos survived the 5 hr exposure to Ta of 42 degrees C. The lethal Ta ranged from 44 degrees C (EP eggs) to 46 degrees C (young embryos). 3. The temperature coefficient (Q10) of fH became smaller than 2 in EP eggs as Ta was decreased or increased from 38 degrees C, implying an incipient homeothermic response of fH.
Animals↗
The effects of chronic exposure to elevated environmental temperature on intestinal morphology and nutrient absorption in the domestic fowl (Gallus domesticus).
1. Exposure of growing broiler chickens to elevated environmental temperature (35 degrees C) for two weeks, markedly reduced food intake (29%) and growth rate (37%) compared to birds maintained at 22 degrees C. 2. These changes in growth were accompanied by increased in vivo jejunal uptakes of galactose (36%) and methionine (50%) measured per unit intestinal dry weight. 3. Both the electrogenic (phloridzin sensitive) and non-electrogenic (phloridzin insensitive) components of galactose absorption were increased by 24 and 52% respectively during the chronic heat stress. 4. The size of the absorptive compartment may be reduced by the heat stress as reflected by decreased villus heights (19%) and wet (26%) and dry (31%) weights per unit length of jejunum. 5. It is suggested that the changes in hexose and amino acid during chronic exposure to elevated ambient temperature may reflect adaptations to optimise nutrient absorption in the face of reduced nutrition and decreases in the size of the absorptive compartment. A functional hypothyroidism (plasma luminal T3 decreased by 66%) associated with heat stress may contribute to the observed alterations in jejunal structure and function.
Animals↗
Effect of exogenous chicken growth hormone (cGH) administration on insulin-like growth factor-I (IGF-I) gene expression in domestic fowl.
The effects of chicken growth hormone (cGH) infusion on insulin-like growth factor (IGF-I) gene expression in rapidly-growing, meat-type chickens was investigated. Chicken GH was infused either continuously or in a pulsatile fashion to 8-week-old birds during a 7-day period. Following cGH infusion, both IGF-I peptide and IGF-I mRNA content were measured in selected tissues. Steady-state IGF-I mRNA abundance was determined by a solution hybridization nuclease protection assay using total cellular RNA obtained from liver, heart, kidney, spleen, epiphyseal growth plate cartilage, gastrocnemius and pectoralis muscles. Continuous infusion of cGH elicited a two-fold increase in IGF-I peptide concentration in the kidney (P < 0.05), while all other tissues remained unchanged by cGH treatment under this infusion pattern. Pulsatile cGH infusion produced a two-fold increase in IGF-I peptide content in the liver, gastrocnemius, and pectoralis muscles (P < 0.05). In contrast with the levels of IGI-I peptide, relative steady-state IGF-I mRNA content was two-fold higher in liver and spleen of birds treated continuously with cGH, but was decreased to 35 and 55% of control birds in heart and pectoralis muscle. Pulsatile cGH infusion resulted in a 64% increase in IGF-I mRNA in the liver and remained unchanged in other tissues. Under both patterns of administration, changes in IGF-I mRNA were not reflected by changes in tissue IGF-I peptide levels. Overall correlations between tissue IGF-I mRNA and peptide levels were low and not significant in the tissues studied, except for liver under pulsatile infusion, in which IGF-I peptide levels paralleled changes in IGF-I mRNA. We conclude that, in chickens, exogenous cGH treatment stimulates hepatic IGF-I transcription and translation only when the pattern of infusion mimics the natural episodic pattern of GH secretion. The low correlation between IGF-I peptide and mRNA levels in extra-hepatic tissues may indicate differential responsiveness to GH in birds, and that in some tissues IGF-I levels are under GH-independent transcriptional controls.
Animals↗
Cyclic AMP levels in various tissues of the domestic fowl (Gallus domesticus) as affected by glucagon, epinephrine and insulin.
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Animals↗
Steroids in the pineal gland of the domestic fowl (Gallus domesticus): cholesterol and its biosynthesis.
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Acetates↗