ADRENOCORTICAL FUNCTION IN THE AUSTRALIAN BRUSH-TAILED POSSUM TRICHOSURUS VULPECULA (KERR)

1973 ◽  
Vol 58 (1) ◽  
pp. 97-109 ◽  
Author(s):  
KHIN AYE THAN ◽  
I. R. McDONALD
Keyword(s):  
Cortisol Concentration ◽  
Adrenocortical Function ◽  
Metabolic Clearance ◽  
Cortisol Secretion ◽  
Trichosurus Vulpecula ◽  
Degree Polynomial ◽  
Acth Stimulation ◽  
Peripheral Plasma ◽  
Ether Anaesthesia ◽  
Secretion Rates

SUMMARY The peripheral plasma concentration and secretion rate of cortisol in the conscious marsupial brush-tailed possum Trichosurus vulpecula (Kerr) was investigated under basal conditions and during maximal corticotrophin (ACTH) stimulation. Cortisol concentration in peripheral plasma was 0·92 ± 0·48 (s.d.) μg/100 ml in males, and 1·01 ± 0·57 in females. It was lowest at 08.00 h, when the possums were asleep and not easily aroused. Although there was a high variance, a third degree polynomial fitted the data plotted against time over 24 h at the 95% level of confidence, indicating a diurnal periodicity. Ether anaesthesia, porcine and synthetic (24 amino acids) ACTH caused plasma cortisol concentrations to rise to maxima of no more than 7 μg/100 ml. The dose-response curve to ACTH indicated a maximum response at 0·12 i.u./kg/h with a potency of approximately 1/6 that found in sheep and 1/20 that found in man. Cortisol secretion rates in non-stimulated possums were 2·71 ± 1·01 μg/kg/h in males and 4·32 ± 1·74 in females. They increased during maximal ACTH stimulation to 6·24 ± 1·58 μg/kg/h in males, and 13·28 ± 7·82 in females. Metabolic clearance rates were lowest in animals not accustomed to repeated blood sampling and rose in subsequent experiments. It is concluded that the adrenal cortex of Trichosurus, like that of eutherian mammals, responds to changes in activity, stressful stimuli and ACTH, but quantitatively, the responses to these stimuli are very much lower.

THE EFFECTS OF HYPOPHYSECTOMY ON ADRENOCORTICAL FUNCTION IN THE DUCK (ANAS PLATYRHYNCHOS)

1971 ◽  
Vol 49 (3) ◽  
pp. 437-457 ◽  
Author(s):  
E. L. BRADLEY ◽  
W. N. HOLMES
Keyword(s):  
Mammalian Species ◽  
Compartment Model ◽  
Liver Glycogen ◽  
Plasma Corticosterone ◽  
Adrenocortical Function ◽  
Metabolic Clearance ◽  
General Effect ◽  
Corticosterone Concentration ◽  
Peripheral Plasma ◽  
Corticosterone Secretion

SUMMARY The general effect of chronic hypophysectomy on organ and body weights, liver glycogen, blood glucose, peripheral plasma corticosterone concentrations, and blood pressure in the duck were similar to those described for several mammalian species. The disappearance and distribution of radioactivity after the administration of [1,2-3H]corticosterone and [1,2-3H]aldosterone was studied according to a single compartment model system. When compared with sham-operated ducks, the apparent volumes of distribution and the biological half-lives of radioactivity in hypophysectomized ducks were significantly increased, and the estimated metabolic clearance rates of [1,2-3H] corticosterone and [1,2-3H]aldosterone were significantly decreased. The patterns of distribution of radioactivity and the rate of metabolism of both hormones returned towards normal when the chronically hypophysectomized ducks were treated with corticotrophin (ACTH). Fourteen days after hypophysectomy the peripheral plasma concentration of corticosterone and the estimated rate of corticosterone secretion by the adrenal fell to 10 and 4%, respectively, of the values observed in sham-operated birds. Examinations of the peripheral plasma corticosterone concentration during the first 30 min after the removal of the adenohypophysis indicated a mean biological half-life for endogenous corticosterone of 13·7 min. The rates of appearance of radioactivity in the bile, intestine and cloaca of the hypophysectomized birds suggested substantial declines in the rates of aldosterone and corticosterone metabolism. These declines could not be accounted for by the reduced rate of glomerular filtration in the hypophysectomized bird. Replacement therapy with ACTH restored the excretory patterns of both steroids towards normal. The quantitative similarities between the effects of hypophysectomy in the duck and several mammalian species make it unnecessary to postulate either a high degree of adrenal autonomy or an extrahypophysial source of ACTH in the control of adrenocortical function in the duck.

scholarly journals Salivary Cortisol: A Better Measure of Adrenal Cortical Function than Serum Cortisol

1983 ◽  
Vol 20 (6) ◽  
pp. 329-335 ◽  
Author(s):  
Ross F Vining ◽  
Robynne A McGinley ◽  
Joseph J Maksvytis ◽  
Kian Y Ho
Keyword(s):  
Salivary Cortisol ◽  
Circadian Variation ◽  
Serum Cortisol ◽  
Normal Pregnancy ◽  
Cortisol Concentration ◽  
Adrenocortical Function ◽  
Cortical Function ◽  
Acth Stimulation ◽  
Non Invasive ◽  
Normal Men

Salivary Cortisol concentration was found to be directly proportional to the serum unbound Cortisol concentration both in normal men and women and in women with elevated cortisol-binding globulin (CBG). The correlation was excellent in dynamic tests of adrenal function (dexamethasone suppression, ACTH stimulation), in normals and patients with adrenal insufficiency, in tests of circadian variation and randomly collected samples. Women in the third trimester of normal pregnancy exhibited elevated salivary Cortisol throughout the day. The relationship between salivary and serum total Cortisol concentration was markedly non-linear with a more rapid increase in salivary concentration once the serum CBG was saturated. The rate of equilibrium of Cortisol between blood and saliva was very fast, being much less than 5 minutes. These data, combined with a simple, stress-free, non-invasive collection procedure, lead us to suggest that salivary Cortisol is a more appropriate measure for the clinical assessment of adrenocortical function than is serum Cortisol.

Adrenocortical functions in a macropodid marsupial Thylogale billardierii

1986 ◽  
Vol 110 (3) ◽  
pp. 471-480 ◽  
Author(s):  
I. K. Martin ◽  
I. R. McDonald
Keyword(s):  
Plasma Glucose ◽  
Glucose Concentration ◽  
Plasma Cortisol ◽  
Tammar Wallaby ◽  
Cortisol Concentration ◽  
Plasma Glucose Concentration ◽  
Metabolic Clearance ◽  
Acth Stimulation ◽  
Plasma Cortisol Concentration ◽  
Red Kangaroo

ABSTRACT In a study of adrenocortical functions in macropodid marsupials, measurements were made of the effects of ACTH infusion, ether stress and adrenaline infusion on plasma corticosteroid and glucose concentrations in wallabies (Thylogale billardierii) provided with indwelling venous catheters. The mean plasma total glucocorticoid concentration in undisturbed males and females was 80 ± 5 (s.e.m.) μg/l, of which more than 90% was cortisol. This fraction declined to 68% of the total at the highest ACTH-stimulated concentration of 225 μg/l, due to an increase in the contribution by 11-deoxycortisol. Although maximal ACTH stimulation (4·5 i.u./kg per h) caused a five- to sixfold increase in cortisol secretion rate, as measured by isotope dilution during constant-rate tracer infusion, plasma cortisol concentration rose only two- to threefold, due to a marked increase in metabolic clearance. Plasma glucose concentration did not change significantly during either short-term (1 h) i.v. infusion or long-term (8 days) i.m. injection of ACTH, even though plasma cortisol concentration was significantly increased. Ether anaesthesia caused a marked hyperglycaemia that preceded an increase in plasma cortisol concentration and was not sustained while plasma cortisol concentration continued to increase. Infusion of adrenaline i.v. at rates sufficient to cause a similar hyperglycaemia had no significant effect on plasma cortisol concentration. A marked hyperglycaemia during xylazine anaesthesia was not associated with an increase in plasma cortisol concentration and was attributable to suppression of insulin secretion. It is concluded that, as in the red kangaroo (Macropus rufus) and the quokka (Setonix brachyurus) and in contrast to the reported effects in the tammar wallaby (Macropus eugenii), neither ACTH, nor the increase in plasma glucocorticoid concentration caused by ACTH administration, influence plasma glucose concentration in Thylogale billardierii. J. Endocr. (1986) 110, 471–480

ADRENOCORTICAL FUNCTION IN A PROTOTHERIAN MAMMAL, TACHYGLOSSUS ACULEATUS (SHAW)

1977 ◽  
Vol 72 (1) ◽  
pp. 41-52 ◽  
Author(s):  
C. SERNIA ◽  
I. R. McDONALD
Keyword(s):  
Plasma Concentrations ◽  
Adrenocortical Function ◽  
Metabolic Clearance ◽  
Production Rates ◽  
Acth Stimulation ◽  
Behavioural Activity ◽  
Constant Rate ◽  
Peripheral Blood Plasma ◽  
High Concentrations ◽  
Tachyglossus Aculeatus

SUMMARY The peripheral plasma concentrations and production rates of corticosterone and cortisol were measured in the conscious, unrestrained echidna (Tachyglossus aculeatus) under basal conditions and during maximal ACTH stimulation. Using Sephadex LH-20 column chromatography and radioligand assay, only cortisol and corticosterone could be detected in the peripheral blood plasma at very low concentrations of 0·07 ± 0·03 (s.e.m.) μg/100 ml and 0·14 ± 0·07 μg/100 ml respectively. Two-hourly sampling over periods of 36–48 h disclosed a diurnal periodicity in the combined plasma concentration of these corticosteroids, the high concentrations corresponding to periods of behavioural activity. Marked, short-term fluctuations in plasma corticosteroid concentration were also observed during periods of more frequent (20 min) sampling. Constant rate i.v. infusion of synthetic ACTH increased the plasma concentrations of both steroids to maximal values of 0·42 ± 0·23 μg cortisol/100 ml and 1·06 ± 0·56 μg corticosterone/100 ml at infusion rates of 1 i.u. ACTH/kg/h. This is approximately 1/160 of the potency of this ACTH in man. The production rates of corticosterone and cortisol, measured by isotope dilution during constant rate i.v. infusion of 3H-labelled tracers, were only 0·35 ± 0·21 and 0·56 ± 0·26 μg/kg/h respectively during saline infusion, and increased to 2·86 ± 3·47 and 2·74 ± 2·07 μg/kg/h during the infusion of 1 i.u. ACTH/kg/h. The metabolic clearance rate of cortisol was greater than that of corticosterone and both were depressed by ACTH. Plasma corticosteroid concentrations were increased after surgery during ether anaesthesia and in sick animals with heavy worm infestation. It is concluded that the adrenal cortex of echidnas responds to ACTH stimulation and stress in a similar way to eutherians, but the level of activity is much lower.

THE CLEARANCE OF RENIN FROM THE PERIPHERAL PLASMA OF THE MARSUPIAL TRICHOSURUS VULPECULA

1969 ◽  
Vol 45 (1) ◽  
pp. 121-129 ◽  
Author(s):  
I. A. REID ◽  
I. R. McDONALD
Keyword(s):  
Decay Curve ◽  
Plasma Renin ◽  
Volume Of Distribution ◽  
Metabolic Clearance ◽  
Trichosurus Vulpecula ◽  
Plasma Renin Concentration ◽  
Peripheral Plasma ◽  
The Difference ◽  
Surgical Manipulations ◽  
Venous Plasma

SUMMARY In the marsupial Trichosurus vulpecula, the decay curve of plasma renin concentration against time, during a period of 4 hr. immediately after either bilateral nephrectomy or i.v. injection of a partially purified homologous renin, could be resolved into two exponential components. The curves in both types of experiment were similar, suggesting a simple twopool system of renin distribution. The half-times of the first and second components were 11·1 ± 2·6 (s.d.) and 217 ± 71·5 min. respectively. As in dogs, the initial volume of distribution of injected renin was equivalent to approximately 10% of body weight. Using this value, and the derivative of the post-nephrectomy decay curve at the time of removal of the second kidney, the renin production rate at this time was calculated to be in the range of 123–1170 units/min. This calculation was justified by demonstrating that the surgical manipulations did not cause any increase in plasma renin concentration. Renal renin production rates, measured in other possums from the difference in renin concentrations of arterial and renal venous plasma, were within the range calculated from the postnephrectomy decay curves. Metabolic clearance rates calculated from the post-nephrectomy decay curves averaged 3·5 ml./min./kg.; and those calculated from the post injection decay curves averaged only 1·9 ml./min./kg. Circulatory changes, due to nephrectomy or renin injection, are the most likely reasons for this discrepancy.

OVARIAN SECRETION RATES OF OESTROGENS, ANDROGENS AND PROGESTERONE IN NORMAL WOMEN AND IN WOMEN WITH PERSISTENT OVARIAN FOLLICLES

1974 ◽  
Vol 77 (3) ◽  
pp. 575-587 ◽  
Author(s):  
F. H. de Jong ◽  
D. T. Baird ◽  
H. J. van der Molen
Keyword(s):  
Menstrual Cycle ◽  
Production Rate ◽  
Follicular Fluid ◽  
Ovarian Follicles ◽  
Dehydroepiandrosterone Sulphate ◽  
Peripheral Plasma ◽  
Normal Women ◽  
Quantitative Contribution ◽  
Secretion Rates ◽  
Venous Plasma

ABSTRACT The concentrations of oestradiol-17β, oestrone, androstenedione, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulphate and progesterone were measured in ovarian venous plasma from one or both ovaries in 4 normal women during different stages of the menstrual cycle and in 4 women with persistent ovarian follicles. In addition the steroid concentrations in peripheral plasma and follicular fluid were estimated. All steroids mentioned, with the exception of dehydroepiandrosterone sulphate, were secreted by the ovaries. The concentrations of oestradiol-17β, oestrone, androstenedione and progesterone were higher in the venous plasma from the ovary containing the developing follicle or corpus luteum than in venous plasma from the contralateral ovary. There was a good correlation between ovarian secretion of the oestrogenic steroids and androstenedione. Finally, the quantitative contribution of the ovarian secretion to the blood production rates of the androgens and progesterone was calculated. The only contributions exceeding 20 % of the blood production rate were those of progesterone and androstenedione during the second half of the cycle.

ADRENOCORTICAL FUNCTION TESTS IN DOGS WITH HYPERFUNCTIONING ADRENOCORTICAL TUMOURS

1979 ◽  
Vol 80 (3) ◽  
pp. 315-319 ◽  
Author(s):  
J. C. MEIJER ◽  
A. A. M. E. LUBBERINK ◽  
A. RIJNBERK ◽  
R. J. M. CROUGHS
Keyword(s):  
Plasma Concentration ◽  
Plasma Cortisol ◽  
Cortisol Concentration ◽  
Adrenocortical Function ◽  
Plasma Cortisol Concentration ◽  
Function Tests ◽  
Lysine Vasopressin ◽  
Adrenocortical Tumours ◽  
Adrenocortical Tumour

The response has been studied in nine dogs with hyperadrenocorticism due to adrenocortical tumours to the administration of dexamethasone, insulin, lysine-vasopressin and tetracosactide by measuring the changes in plasma cortisol concentration. Administration of dexamethasone did not produce a decrease in the plasma concentration of cortisol in any of these dogs. Administration of insulin caused slight increases in the plasma concentration of cortisol in four out of eight dogs. Lysine-vasopressin increased the plasma concentration of cortisol in eight out of nine dogs, three responded supranormally. Eight out of the nine dogs responded to tetracosactide administration, three responded supranormally. It is concluded that in the dog, in contrast to man, the lysine-vasopressin test cannot be used to differentiate between pituitary-dependent hyperadrenocorticism and hyperadrenocorticism due to an adrenocortical tumour. Apparently pituitary ACTH is not completely depleted in dogs with hyperfunctioning adrenocortical tumours.

Reproducibility of the cortisol response to stimulation with a low dose of ACTH(1–24): the effect of basal cortisol levels and comparison of low-dose with high-dose secretory dynamics

1993 ◽  
Vol 136 (1) ◽  
pp. 167-172 ◽  
Author(s):  
S. Crowley ◽  
P. C. Hindmarsh ◽  
J. W. Honour ◽  
C. G. D. Brook
Keyword(s):  
Cortisol Level ◽  
Low Dose ◽  
Standard Dose ◽  
Serum Cortisol ◽  
Cortisol Concentration ◽  
Acth Stimulation ◽  
Basal Cortisol ◽  
Basal Cortisol Level ◽  
Adrenal Response ◽  
Serum Cortisol Concentration

ABSTRACT We compared the reproducibility and repeatability of the acute adrenal response to low doses (90 and 500 ng/1·73 m2) of Synacthen (ACTH(1–24)) with that of the standard dose (250 μg/1·73 m2). We also examined the effect of basal cortisol levels on peak values achieved after stimulation with a low dose. ACTH(1–24) was given to six male volunteers: 90 ng/1·73 m2 twice at 90-min intervals on day 1, and 90 and 500 ng/1·73 m2 once on day 2 and 250 μg/1·73 m2 once on day 3. The rise in serum cortisol concentration with repeated low doses of ACTH was not attenuated (161 ± 49 (s.d.) nmol/l on initial vs 150 ± 41 nmol/l on repeat stimulation; P = 0·5) and this was reproducible (161 ± 49 nmol/l on day 1 vs 148 ± 15 nmol/l on day 2; P = 0·6). A dose of 500 ng ACTH(1–24)/1·73 m2 produced a maximal adrenal response in that the rise in serum cortisol concentration at 20 min was identical with that produced at the same time by the standard dose of 250 μg/1·73 m2. There was a strong positive correlation between the basal cortisol level and peak cortisol concentration after low-dose ACTH stimulation (r = 0·93, P < 0·001) but not between the basal cortisol level and the incremental rise (r= −0·1, P = 0·69). These results suggest that the cortisol response to low-dose ACTH stimulation is reproducible and not attenuated by repeat stimulation at 90-min intervals. The incremental rise in serum cortisol concentration after ACTH stimulation appears constant in these situations and is not influenced by the basal cortisol level. When there is concern that the standard dose may be excessive and mask subtle but important changes in adrenal function, the low dose (500 ng) of ACTH should be used. Journal of Endocrinology (1993) 136, 167–172

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