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.

THE EFFECTS OF HYPOPHYSECTOMY ON THE METABOLISM OF ADRENAL STEROIDS IN THE PIGEON (COLUMBA LIVIA)

1972 ◽  
Vol 52 (3) ◽  
pp. 435-450 ◽  
Author(s):  
MO YIN CHAN ◽  
E. L. BRADLEY ◽  
W. N. HOLMES
Keyword(s):  
Replacement Therapy ◽  
Methylene Chloride ◽  
Compartment Model ◽  
Columba Livia ◽  
Plasma Corticosterone ◽  
Volume Of Distribution ◽  
Model Systems ◽  
Metabolic Clearance ◽  
Corticosterone Concentration ◽  
Plasma Fractions

SUMMARY The distribution and disappearance of radioactivity after the intravenous administration of [1,2-3H]corticosterone and [1,2-3H]aldosterone to the pigeon were studied according to one- and two-compartment model systems. The volume of distribution (AVD) of the total and methylene chlorideextractable radioactivity in the plasma of hypophysectomized pigeons injected with labelled corticosterone was significantly increased. Also the biological half-life (T½) of each radioactive fraction in plasma was significantly prolonged. No significant change in the metabolic clearance rate (MCR) of labelled corticosterone was observed in the hypophysectomized pigeon. The AVD of the total and methylene chloride-extractable tritium in the plasma of the hypophysectomized pigeon injected with labelled aldosterone was unchanged but the T½ of both plasma fractions was significantly prolonged. The estimated MCR of labelled aldosterone was significantly diminished. The concentration of total fluorogenic corticosteroid in plasma from the chronically hypophysectomized pigeon was reduced to one-third of that in the sham-operated bird, and corticotrophin-replacement therapy restored the concentration to normal. After hypophysectomy, the plasma corticosterone concentration was reduced to 20% of the concentration in the sham-operated birds, and replacement therapy with corticotrophin again restored the plasma levels to normal. Estimation of the endogenous corticosterone secretory rates indicated that chronic hypophysectomy was accompanied by a decline commensurate with the reduction in the plasma corticosterone concentration.

Adrenocortical function in aging exercise-trained rats

1977 ◽  
Vol 43 (5) ◽  
pp. 839-843 ◽  
Author(s):  
J. A. Severson ◽  
R. D. Fell ◽  
J. G. Tuig ◽  
D. R. Griffith
Keyword(s):  
Age Groups ◽  
Plasma Corticosterone ◽  
Treadmill Running ◽  
Adrenocortical Function ◽  
Elevated Plasma ◽  
Corticosterone Concentration ◽  
Relationship Of ◽  
The Relationship

Plasma corticosterone concentrations and in vitro adrenal secretion of corticosterone were determined in exercise-trained rats. Rats, 100, 200, and 300 days of age, were trained for a 10-wk period by treadmill running. Following the training program, rats were subjected to an acute bout of swimming. Acute swimming elevated plasma corticosterone concentrations in all age groups. At 170 days of age, the plasma corticosterone concentration following swimming was higher in exercise-trained rats than in controls. The opposite was true of acutely swum rats at 270 and 370 days of age. Acute swimming elevated the in vitro adrenal gland response to adrenocorticotropic hormone stimulation in control rats at all ages and in trained rats at 170 days of age. The in vivo relationship of epinephrine and the pituitary adrenal system is suggested as a mechanism which could have caused this response. The relationship of secretion rates to plasma corticosterone concentrations indicated that extra-adrenal mechanisms, such as decreased turnover, were also responsible for the elevated plasma corticosterone levels observed in response to acute swimming.

Effect of melittin on pituitary-adrenal responsiveness to stress

1988 ◽  
Vol 119 (3) ◽  
pp. 339-344 ◽  
Author(s):  
Jon D. Dunn ◽  
Jerald J. Killion
Keyword(s):  
Significant Influence ◽  
Restraint Stress ◽  
Surgical Stress ◽  
Plasma Corticosterone ◽  
Adrenocortical Function ◽  
Female Rat ◽  
Corticosterone Concentration ◽  
Initial Exposure ◽  
Adrenal Response ◽  
Sustained Increase

Abstract. We previously have shown that melittin evokes a sustained increase in plasma corticosterone levels of the female rat. Significant increases occurred only during the morning and the duration of the response was increased from 48 h to 8 days by a second milittin injection 3 days after initial exposure to melittin. To further evaluate the effect of melittin on adrenocortical function, rats were given melittin at 09.00 h on days 1 and 4 and on day 8 rats were subjected to a variety of different stresses. Saline-injected rats served as controls. Blood for determining non-stress and stress levels of corticosterone concentration (RIA) was collected by decapitation. In all cases morning but not afternoon non-stress plasma corticosterone levels of melittin-injected rats were higher than those of saline-injected controls; afternoon non-stress corticosterone levels did not differ between groups. Melittin- and saline-treated rats showed comparable corticosterone responses to a morning 2-min restraint stress. In contrast, melittin treatment facilitated the pituitary-adrenal response to rotational and surgical stress as well as the stress of removing one rat from a cage of two. Fifteen min after removal of the first rat of a cage of two, plasma corticosterone levels of the melittin-injected rat were significantly higher than those of saline-injected rats. Likewise, plasma corticosterone levels of melittin-treated rats were higher (P < 0.05) than those of saline-injected rats 15 min after rotational (10 rpm) and surgical (jugular cutdown and blood withdrawal) stress. Collectively these data indicate that exposure to melittin (and/or the resulting increase in morning corticosterone levels) may have a significant influence on the pituitary-adrenal responsiveness to stress.

Adrenocortical responses of ducks to treadmill exercise

1982 ◽  
Vol 94 (1) ◽  
pp. 141-146 ◽  
Author(s):  
S. Harvey ◽  
J. G. Phillips
Keyword(s):  
Treadmill Exercise ◽  
Plasma Corticosterone ◽  
Pretreatment Level ◽  
Corticosterone Concentration ◽  
Domestic Ducks ◽  
Corticosterone Secretion ◽  
Corticosterone Response ◽  
Response To Exercise ◽  
Adrenocortical Responses ◽  
Stationary Control

The influence of treadmill exercise on corticosterone secretion has been determined in domestic ducks. In birds unused to such exercise the concentrations of plasma corticosterone were markedly increased (> fourfold) after 15 or 30 min of treadmill exercise (1·1 km/h at 3 ° grade) and the level remained high (between 30 and 40 ng/ml) throughout 90 min of exercise. This increase in corticosterone secretion accompanied a similar increase in colon temperature and was independent of the plasma glucose level. After exercise the corticosterone concentration declined to the pretreatment level within 60 min of recovery. In birds used to the exercise the corticosterone response to a standard (30 min) period of exercise was diminished (by 77·6% in comparison with untrained birds and was no greater than the response (1·7-fold) in stationary control birds after handling and bleeding. The diminution of the corticosterone response to exercise may be due to the trained birds becoming fitter and better able to perform the work involved.

Effect of adenosine analogues on plasma corticosterone concentration in rats

1992 ◽  
Vol 127 (5) ◽  
pp. 471-475 ◽  
Author(s):  
Edmund Przegaliński ◽  
Bogusława Budziszewska ◽  
Anna Grochmal
Keyword(s):  
Adenosine Receptor ◽  
Corticosterone Level ◽  
Plasma Corticosterone ◽  
Receptor Antagonists ◽  
Corticosterone Concentration ◽  
Adenosine Analogues ◽  
Negative Results ◽  
Corticosterone Secretion ◽  
Corticosterone Response ◽  
Pharmacological Blockade

In this study we examined the effect of the adenosine analogues: N6-cyclohexyladenosine, L-N6-phenylisopropyladenosine and 5′-N-ethylcarboxamidoadenosine on the plasma corticosterone concentration in rats. It was found that N6-cyclohexyladenosine (0.1–3.0 mg/kg), L-N6-phenylisopropyladenosine (0.1–1.0 mg/kg) and 5′-N-ethylcarboxamidoadenosine (0.01–1.0 mg/kg) dose-dependently increased the plasma corticosterone level. The effects of N6-cyclohexyladenosine (0.1 mg/kg) and L-N6-phenylisopropyladenosine (0.1 mg/kg) were completely blocked in animals pretreated with dexamethasone (3 × 1 mg/kg), as well as in animals with a pharmacological blockade of the release of hypothalamic corticotropin-releasing factor induced by chloropromazine (10 mg/kg), morphine (20 mg/kg) and nembutal (25 mg/kg), whereas the corticosterone response to 5′-N-ethylcarboxamidoadenosine (0.01 mg/kg) was blocked in dexamethasone-pretreated rats only. On the other hand, the adenosine receptor antagonists: 8-(p-sulfophenyl)-theophylline (30 mg/kg), 8-phenyltheophylline (10 and 30mg/kg), 1,3-dipropyl-8-(2-amino-4-chloro)-phenylxanthine (1 and 3 mg/kg) and 1,3-dipropyl-7-methylxanthine (1 mg/kg) did not affect the corticosterone response to N6-cyclohexyladenosine, L-N6-phenylisopropyladenosine or 5′-N-ethylcarboxamidoadenosine. The obtained results indicate that N6-cyclohexyladenosine and L-N6-phenylisopropyladenosine stimulate the corticosterone secretion at the hypothalamic level, whereas 5′-N-ethylcarboxamidoadenosine is likely to act at the pituitary level. Although the effects produced by the adenosine analogues show that both A1 and A2 receptors are involved in the corticosterone response, negative results of the interaction studies with adenosine receptor antagonists indicate that further experiments are necessary to elucidate this problem.

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.

Feedback Inhibition of Adrenocorticotropin Release by Corticosterone Infusions in the Adrenalectomized Rat

1975 ◽  
Vol 53 (3) ◽  
pp. 475-478 ◽  
Author(s):  
William Rotsztejn ◽  
Josée Lalonde ◽  
Maurice Normand ◽  
Claude Fortier
Keyword(s):  
Body Weight ◽  
Infusion Rate ◽  
Feedback Inhibition ◽  
Inhibitory Effect ◽  
Plasma Corticosterone ◽  
Rat Plasma ◽  
Metabolic Clearance ◽  
Experimental Conditions ◽  
Corticosterone Concentration ◽  
Acth Release

Advantage was taken of a specific and sensitive bioassay for rat plasma adrenocorticotropin (ACTH) based on the dispersion of rat adrenal cells with trypsin, to investigate the relationship between plasma corticosterone concentration and inhibition of ACTH release under steady-stale conditions achieved by graded rates (0–5.12 μg/min per 100 g body weight) of intravenous infusion of the steroid for 45 min in 28-day adrenalectomized rats. In contrast to prior reports involving suppression of stress-induced ACTH release, the inhibitory effect of corticosterone was shown, under our experimental conditions, to be exerted also on the basal rate of ACTH secretion. Indeed, a slight though not significant decrease of plasma ACTH concentration was observed with the corticosterone infusion rate of 0.64 μg/min per 100 g body weight, and further progressive and highly significant drops in concentration were recorded for infusion rates of 2.56 and 5.12 μg/min per 100 g body weight. An increase of the metabolic clearance rate of corticosterone, observed as a function of the infusion rate, was ascribed to saturation by the steroid of the plasma transcortin binding sites.

Reduced adrenocortical function and increased thyroid function in fasted and refed chickens

1983 ◽  
Vol 98 (1) ◽  
pp. 129-135 ◽  
Author(s):  
S. Harvey ◽  
H. Klandorf
Keyword(s):  
Corticosterone Level ◽  
Plasma Corticosterone ◽  
Metabolic Effects ◽  
Adrenocortical Function ◽  
Free Access ◽  
Similar Reduction ◽  
Corticosterone Concentration ◽  
Post Feeding ◽  
Access To Food ◽  
Food Consumed

The deprivation of food for 48 h markedly increased (P< 0·001) the corticosterone concentration in the plasma of 7- to 8-week-old chickens. When fasted birds were refed for 2 min or 5 s the corticosterone concentration fell to the level in fed birds within 30 min of refeeding. In fasted and refed birds the plasma corticosterone concentration remained lowered for at least 150 min after a 2-min period of refeeding, whereas in birds refed for 5 s the concentration had increased within 120 min to that in fasted birds. When fasted birds were refed 1, 5, 15 or 30 g diet the corticosterone level was again markedly reduced (P< 0·001) within 45 min of refeeding. The magnitude of this post-feeding decline was unrelated to the amount of food eaten, although its duration was; the level in birds refed 1, 5 or 15 g food increasing to that in fasted birds within 90, 135 and 225 min respectively. The corticosterone level in birds refed 30 g diet remained reduced for at least 225 min but increased to that in fasted birds 24 h after refeeding. The initial decline in the corticosterone concentration was unrelated to the consumption of food, since a similar reduction in the corticosterone level was observed in fasted birds which were given the sight of food but prevented from eating it by Perspex lids attached to the food troughs. This initial decline in the corticosterone level was not a result of stress, as it did not occur in fasted control birds. These results suggest that the adrenocortical changes in fasted and refed birds is initially mediated by a conditioned neural stimulus (reinforcement) and is maintained as a result of peripheral metabolic effects of ingested food. In fasted chickens the concentration of plasma tri-iodothyronine (T3) was greatly reduced (P<0·001) in comparison with fed birds. When fasted birds were refed for 2 min or with 5, 15 or 30 g diet, the level of plasma T3 was increased (P < 0·05) 90 min after refeeding although not to the level in birds which had free access to food. The magnitude and duration of this increase was related to the amount of food consumed and was not observed in birds refed for 5 s or with 1 g food or in fasted birds given sight of but not access to food.

Corticosterone secretion after inhibition of prostaglandin synthesis by indomethacin

1981 ◽  
Vol 240 (2) ◽  
pp. E131-E135
Author(s):  
M. E. Thompson ◽  
G. A. Hedge
Keyword(s):  
Plasma Corticosterone ◽  
Control Group ◽  
Metabolic Clearance ◽  
Plasma Acth ◽  
Corticosterone Secretion ◽  
Basal Plasma ◽  
Prostaglandin F ◽  
Acth Concentration ◽  
Inhibition Of Prostaglandin Synthesis ◽  
Sites Of Action

Systemic indomethacin (Ind) administration decreased prostaglandin F (PGF) content of the rat adrenal to less than 1.4 pg/mg. This was less than 5% of the adrenal PGF content in the gelatin-treated (Gel) control group (34 pg/mg). Basal plasma corticosterone levels were increased by the Ind treatment. Since the calculated metabolic clearance rate for corticosterone was unchanged, this increase was attributed to an enhanced adrenal secretion rate that was secondary to elevated plasma ACTH concentration. Ether exposure in the presence of Ind did not stimulate a normal rise in plasma corticosterone or adrenal corticosteroidogenesis. Adrenal responsiveness to exogenous ACTH was reduced after Ind treatment. There was a normal rise in plasma ACTH levels following ether exposure confirming the adrenal as the site of inhibition. Systemic Ind treatment thus appears to have two sites of action in altering plasma corticosterone levels: 1) a direct effect on the adrenal, inhibiting normal secretion in response to acute elevations of plasma ACTH, and 2) an action at the pituitary or hypothalamic level, eliciting an increase in basal ACTH secretion.

Adrenocortical function in response to myocardial necrosis in exercise-trained rats

1978 ◽  
Vol 44 (1) ◽  
pp. 104-108 ◽  
Author(s):  
J. A. Severson ◽  
R. D. Fell ◽  
D. R. Griffith
Keyword(s):  
Myocardial Necrosis ◽  
Plasma Corticosterone ◽  
Treadmill Running ◽  
Male Rats ◽  
Adrenocortical Function ◽  
Subcutaneous Injections ◽  
Corticosterone Secretion ◽  
Virgin Male ◽  
And Control

Plasma corticosterone concentrations and in vitro adrenal secretion of corticosterone was determined in exercise-trained rats. Virgin, male rats, 100 days of age, were trained for an 11-wk period by treadmill running. Following the training program, rats were subjected to two subcutaneous injections of l-isoproterenol 24 h apart and killed 24 h after the second injection. All exercise-trained rats survived isoproterenol treatment, while 44% of the control rats died. Plasma corticosterone concentrations were elevated only in exercise-trained rats treated with isoproterenol. Control rats treated with isoproterenol had plasma corticosterone concentrations similar to that in control and exercise-treated rats given placebo injections. Exercise training reduced adrenocortical responsiveness to ACTH in vitro, but isoproterenol treatment increased in vitro responsiveness to ACTH in exercise-trained and control rats. Total unstimulated corticosterone secretion rates in vitro were similar. The reason for better rat survival in exercise-trained rats is unknown; however, improved energy metabolism, depressed aldosterone secretion, or both are suggested as reasons for the better survival of exercise-trained rats.

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