scholarly journals Effect of delayed plasma centrifugation on equine adrenocorticotropic hormone concentration

2019 ◽  
Vol 31 (4) ◽  
pp. 585-587 ◽  
Author(s):  
Kayla N. Shepard ◽  
John C. Haffner ◽  
Dwana L. Neal ◽  
Steven T. Grubbs ◽  
Greg L. Pearce
Keyword(s):  
Whole Blood ◽  
Adrenocorticotropic Hormone ◽  
Animal Health ◽  
Pars Intermedia ◽  
Plasma Acth ◽  
Cornell University ◽  
Diagnostic Center ◽  
Acth Concentration ◽  
Baseline Values ◽  
The Mean

Plasma adrenocorticotropic hormone (ACTH) concentration is used in the diagnosis of pituitary pars intermedia dysfunction (PPID) in horses. We enrolled 10 horses, 5 PPID-positive and 5 PPID-negative, in our study, September 20–22, 2016. On day 0, 5 mL of whole blood was collected into each of 6 EDTA tubes and immediately placed in a refrigerator at 7°C. One tube was centrifuged within 15 min of collection, followed by centrifugation of one tube from each horse at 4, 8, 12, 24, and 36 h following collection. At each time, centrifuged plasma was pipetted into 1.5-mL polypropylene tubes and stored at −80°C. None of the plasma samples were turbid, hemolyzed, or icteric. Plasma was shipped frozen with cold packs overnight to the Animal Health Diagnostic Center of Cornell University (Ithaca, NY) for analysis. The percent change from baseline (PCFB) was reported to standardize the data given that baseline values differed. The mean PCFB was 2.8 (95% confidence interval: –2.9%, 7.0%). Neither refrigeration of whole blood for up to 36 h prior to centrifugation nor freezing affected plasma ACTH concentrations significantly.

Vasopressin and angiotensin II in reflex regulation of ACTH, glucocorticoids, and renin: effect of water deprivation

1992 ◽  
Vol 263 (4) ◽  
pp. R762-R769 ◽  
Author(s):  
V. L. Brooks ◽  
L. C. Keil
Keyword(s):  
Angiotensin Ii ◽  
Water Deprivation ◽  
Adrenocorticotropic Hormone ◽  
Renin Secretion ◽  
Ang Ii ◽  
Elevated Plasma ◽  
Plasma Acth ◽  
Vasopressin Antagonist ◽  
Acth Concentration ◽  
V2 Antagonist

Angiotensin II (ANG II) and vasopressin participate in baroreflex regulation of adrenocorticotropic hormone (ACTH), glucocorticoid, and renin secretion. The purpose of this study was to determine whether this participation is enhanced in water-deprived dogs, with chronically elevated plasma ANG II and vasopressin levels, compared with water-replete dogs. The baroreflex was assessed by infusing increasing doses of nitroprusside (0.3, 0.6, 1.5, and 3.0 micrograms.kg-1.min-1) in both groups of animals. To quantitate the participation of ANG II and vasopressin, the dogs were untreated or pretreated with the competitive ANG II antagonist saralasin, a V1-vasopressin antagonist, or combined V1/V2-vasopressin antagonist, either alone or in combination. The findings were as follows. 1) Larger reflex increases in ANG II, vasopressin, and glucocorticoids, but not ACTH, were produced in water-deprived dogs compared with water-replete dogs. 2) ANG II blockade blunted the glucocorticoid and ACTH responses to hypotension in water-deprived dogs, but not water-replete dogs. In contrast, vasopressin blockade reduced the ACTH response only in water-replete dogs. 3) Vasopressin or combined vasopressin and ANG II blockade reduced the plasma level of glucocorticoids related either to the fall in arterial pressure or to the increase in plasma ACTH concentration in water-replete dogs, and this effect was enhanced in water-deprived dogs. 4) In both water-deprived and water-replete animals, saralasin and/or a V1-antagonist increased the renin response to hypotension, but a combined V1/V2-antagonist did not. These results reemphasize the importance of endogenous ANG II and vasopressin in the regulation of ACTH, glucocorticoid, and renin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Plasma adrenocorticotropic hormone concentration in horses decreases after freezing for 60 days

2019 ◽  
Vol 31 (6) ◽  
pp. 856-858
Author(s):  
John C. Haffner ◽  
Dwana L. Neal ◽  
Rhonda M. Hoffman ◽  
Steven T. Grubbs
Keyword(s):  
Repeated Measures ◽  
Adrenocorticotropic Hormone ◽  
Mixed Model ◽  
Statistical Significance ◽  
Hormone Concentration ◽  
Plasma Acth ◽  
Acth Concentration ◽  
The Stability ◽  
Over Time

We investigated the stability of adrenocorticotropic hormone (ACTH) in plasma after freezing for different lengths of time. The plasma ACTH concentrations of 12 horses were measured on day 0 (baseline) and over time, after stimulation with thyrotropin-releasing hormone. Samples were stored at −80°C for 3, 7, 30, 60, and 90 d, or at −20°C for 3, 7, 30, and 60 d, or between ice packs at −20°C for 3 and 7 d prior to determination of ACTH concentration. ACTH concentrations were compared to baseline (non-frozen day 0 plasma) for each storage method using a mixed model with repeated measures in which each horse served as its own control and day was the repeated effect. Statistical significance was set at p ≤ 0.05, and 0.05 < p < 0.10 was considered a trend. Plasma ACTH frozen at −20°C or at −80°C resulted in degradation of ACTH compared to baseline samples at 60 and 90 d respectively. There was no degradation of ACTH after 7 d when stored between ice packs, or before 30 d at −20°C, or before 60 d at −80°C.

scholarly journals The Effect of Supplementation with Selenium and Vitamin E in Psoriasis

1989 ◽  
Vol 26 (1) ◽  
pp. 83-88 ◽  
Author(s):  
G M Fairris ◽  
Barbara Lloyd ◽  
Lesley Hinks ◽  
Pauline J Perkins ◽  
Barbara E Clayton
Keyword(s):  
Vitamin E ◽  
Blood Plasma ◽  
Whole Blood ◽  
Selenium Concentration ◽  
Plasma Vitamin ◽  
Red Cell ◽  
Selenium Status ◽  
Baseline Values ◽  
The Mean ◽  
Plasma Vitamin E

Since reduced concentrations of selenium in whole blood, plasma and white cells had previously been observed in psoriasis, 69 patients were supplemented daily with either 600 μg of selenium-enriched yeast, 600 μg of selenium-enriched yeast plus 600 IU of vitamin E or a placebo for 12 weeks. Before supplementation, the patients' mean concentrations of selenium in whole blood and plasma were reduced compared with those of matched healthy controls but their red cell glutathione peroxidase (GSH-Px) activity was normal. After 12 weeks supplementation the patients' mean whole blood, plasma and platelet selenium concentrations, platelet GSH-Px activity and plasma vitamin E concentration had risen significantly from the baseline values but their mean skin selenium concentration and red cell GSH-Px activity remained unchanged. The mean white cell selenium concentration rose only in the group receiving selenium alone. Neither supplementation regimen reduced the severity of psoriasis or produced side-effects. The increase in platelet GSH-Px activity suggests that the supplements were bioavailable and that the patients' selenium status may have been reduced prior to supplementation. The failure of the selenium content of the skin to increase may explain why the patients' psoriasis remained unchanged during supplementation.

Reduced adrenal cortical sensitivity to ACTH in lambs with cut splanchnic nerves

1986 ◽  
Vol 110 (1) ◽  
pp. 81-85 ◽  
Author(s):  
A. V. Edwards ◽  
C. T. Jones ◽  
S. R. Bloom
Keyword(s):  
Adrenal Cortex ◽  
Splanchnic Nerve ◽  
Significant Rise ◽  
Plasma Acth ◽  
Nerve Activity ◽  
Splanchnic Nerves ◽  
Acth Concentration ◽  
The Mean ◽  
Arterial Plasma ◽  
Mean Concentration

ABSTRACT The possibility that the sensitivity of the adrenal cortex to endogenous ACTH may be affected by splanchnic nerve activity has been investigated in conscious, weaned, 5- to 8-month-old lambs. The animals were atropinized (0·5 mg/kg) and tested with an i.v. infusion of noradrenaline (333 ng/kg per min for 10 min), which produced a significant rise in the mean concentration of both ACTH and cortisol in the arterial plasma. In lambs tested at least 7 days after section of both splanchnic nerves, just below the diaphragm, the rise in plasma ACTH concentration was significantly greater, and that in plasma cortisol significantly less, than in control lambs. The mean plasma ACTH and cortisol concentrations were linearly related to one another in both groups (r = 0·93 and 0·92) but the sensitivity of the adrenal cortex to the steroidogenic action of ACTH appeared to have been roughly halved 1 week after bilateral splanchnic nerve section. J. Endocr. (1986) 110, 81–85

CHANGES IN THE CONCENTRATION OF ADRENOCORTICOTROPHIN AND CORTICOSTEROID IN THE PLASMA OF FOETAL SHEEP IN THE LATTER HALF OF PREGNANCY AND DURING LABOUR

1977 ◽  
Vol 72 (3) ◽  
pp. 293-300 ◽  
Author(s):  
C. T. JONES ◽  
K. BODDY ◽  
J. S. ROBINSON
Keyword(s):  
Maternal Plasma ◽  
Plasma Acth ◽  
Pregnant Sheep ◽  
Acth Concentration ◽  
The Mean ◽  
Arterial Plasma ◽  
Mean Concentration

SUMMARY The changes in plasma ACTH concentration of pregnant sheep and their foetuses during the latter half of pregnancy and during labour were studied. Before 140 days of gestation the mean concentration in foetal arterial plasma was 117 ± 19 (s.e.m.) pg/ml which rose to a mean of 286 ± 63 pg/ml. The rise in ACTH occurred at about the same time as, but not before, the rise in corticosteroid concentration in foetal plasma. The maternal plasma ACTH concentration did not change during the latter half of pregnancy and had a mean concentration of 64 ± 9 pg/ml. During labour there was a progressive rise in the ACTH concentration in foetal plasma which was not associated with any corticosteroid changes. Ethanol did not suppress labour but reduced the ACTH concentration in foetal plasma.

Control of canine ACTH by corticosteroids: an integral feedback effect of steroids

1989 ◽  
Vol 257 (2) ◽  
pp. R427-R430 ◽  
Author(s):  
M. Keller-Wood
Keyword(s):  
Time Domain ◽  
Adrenocorticotropic Hormone ◽  
Corticosteroid Treatment ◽  
Steroid Treatment ◽  
Feedback Signal ◽  
Plasma Acth ◽  
Corticosteroid Dose ◽  
Treatment Changes ◽  
The Mean ◽  
Total Interval

These experiments were designed to test whether the pattern of change in plasma corticosteroid or the total corticosteroid dose is important in determining the degree of inhibition of adrenocorticotropic hormone (ACTH) responses to stress by corticosteroid intermediate-delayed feedback. Five conscious dogs were studied. The ACTH response to induced hypoglycemia was measured after no prior corticosteroid feedback signal or after a corticosteroid feedback signal produced by infusion, two bolus injections, or three bolus injections of cortisol and corticosterone. The total corticosteroid dose (45 micrograms/kg) and the total interval of steroid treatment (60-30 min before hypoglycemia) were the same in all three cases of corticosteroid treatment. Changes in plasma glucose concentration during induced hypoglycemia were not altered by corticosteroid treatment. The plasma ACTH response to hypoglycemia was inhibited by all three patterns of treatment with corticosteroids. The inhibition of ACTH response was not significantly altered among the patterns of treatment with corticosteroids. The data suggest that the integrated (total) or the mean change in plasma corticosteroid concentration over time determines the degree of inhibition of stimulated ACTH in this time domain.

Evidence for reset of regulated cortisol in pregnancy: studies in adrenalectomized ewes

1998 ◽  
Vol 274 (1) ◽  
pp. R145-R151 ◽  
Author(s):  
Maureen Keller-Wood
Keyword(s):  
Plasma Cortisol ◽  
Adrenocorticotropic Hormone ◽  
Cortisol Concentration ◽  
Plasma Acth ◽  
Basal Cortisol ◽  
Acth Concentration ◽  
In Pregnancy

These studies test the hypothesis that the increased adrenocorticotropic hormone (ACTH) and cortisol in pregnancy reflect a reset of regulated plasma cortisol concentrations. Ewes were sham operated (Sham) or adrenalectomized (ADX) at ∼108 days gestation. Adrenalectomized ewes were replaced with aldosterone (3 μg ⋅ kg−1 ⋅ day−1) and with cortisol at either of two doses (ADX + 0.6 and ADX + 1.0 mg ⋅ kg−1 ⋅ day−1); the ewes were also studied postpartum. Plasma cortisol concentrations in ADX + 0.6 ewes (5.3 ± 1.3 ng/ml) were similar to the Sham ewes postpartum (5.5 ± 0.6 ng/ml), whereas ADX + 1.0 concentrations (8.9 ± 1.0 ng/ml) were similar to pregnant Sham ewes (9.5 ± 1.9 ng/ml). Plasma ACTH concentrations were significantly increased in the pregnant ADX + 0.6 ewes (273 ± 44 pg/ml) relative to pregnant Sham ewes (84 ± 9 pg/ml) or the same ewes postpartum (42 ± 9 pg/ml). Plasma ACTH concentrations were not different among the groups postpartum. Acute increases in plasma cortisol to 15–25 ng/ml produced similar inhibition in all groups. These results suggest that pregnancy resets the basal cortisol concentration required for normalization of basal ACTH concentration.

THE EFFECT OF METYRAPONE ON CORTICOTROPHIN SECRETION

1972 ◽  
Vol 52 (3) ◽  
pp. 517-524 ◽  
Author(s):  
R. A. DONALD ◽  
E. A. ESPINER ◽  
D. W. BEAVEN
Keyword(s):  
Replacement Therapy ◽  
Diurnal Rhythm ◽  
Acth Level ◽  
Plasma Acth ◽  
Significant Difference ◽  
Acth Concentration ◽  
The Mean ◽  
Adrenal Disease ◽  
Normal Controls ◽  
Acth Release

SUMMARY The plasma immunoreactive corticotrophin (ACTH) response to metyrapone (1 g orally at 08.00 h, and 6 hourly thereafter for 48 h) was analysed in 20 patients with a normal oxogenic steroid response. A greater than threefold rise in the mean plasma ACTH concentration was observed within 24 h. The mean plasma ACTH level at 08.00 h on the 2nd day of the test was significantly higher than the mean level at 16.00 h, indicating that the diurnal rhythm in ACTH release persists despite metyrapone administration. The degree of rhythmicity, as assessed by the ratio of the means of the 08.00 and 16.00 h ACTH values on the 2nd day of metyrapone administration, was comparable to, but slightly less than that observed in untreated normal controls. The ACTH response to reduction of circulating cortisol levels was also studied by interrupting steroid replacement therapy for 24 h in eight patients with adrenal disease. The observed increase in plasma ACTH was more variable than that after metyrapone, the rapidity of the ACTH rise possibly being influenced by the details of previous replacement therapy and the severity of the adrenal disease. There was no significant difference in the plasma ACTH response to metyrapone and insulin-induced hypoglycaemia in 13 patients whose pituitary function had been assessed by each of these procedures.

Does intracarotid PGE2 increase plasma ACTH concentration in conscious adult ewes?

1991 ◽  
Vol 261 (3) ◽  
pp. E395-E401
Author(s):  
T. A. Cudd ◽  
C. E. Wood
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Carotid Artery ◽  
Arterial Pressure ◽  
Adrenocorticotropic Hormone ◽  
Plasma Renin ◽  
Plasma Acth ◽  
Acth Secretion ◽  
Human Contact ◽  
Acth Concentration

The hypothesis that prostaglandin E2 (PGE2) is a circulating mediator of adrenocorticotropic hormone (ACTH) secretion in sheep was tested in conscious adult ewes using 30-min carotid artery infusions of 0, 5, 10, 100, and 500 ng.kg-1. min-1 PGE2 in saline. ACTH, cortisol, and aldosterone were significantly increased during the 500 ng.kg-1.min-1 infusion (166 +/- 61 to 233 +/- 38 pg/ml, 27 +/- 5 to 45 +/- 2 ng/ml, and 52 +/- 11 to 85 +/- 25 pg/ml, respectively). PGE2 infusions of 100 ng.kg-1.min-1 increased ACTH from 104 +/- 31 to 168 +/- 31 pg/ml and cortisol from 18 +/- 5 to 42 +/- 2 ng/ml. PGE2 infusions did not increase arginine vasopressin, plasma renin activity, or hematocrit. Heart rate and mean arterial pressure were minimally but significantly increased during the 500 ng.kg-1.min-1 infusion, from 84.9 +/- 2.8 to 99.3 +/- 5.4 beats/min and 95.5 +/- 1.8 to 101.0 +/- 3.4 mmHg, respectively. In a second study to test whether lower infusion rates of PGE2 increase plasma ACTH in sheep with lower resting hormone concentrations, sheep were infused and sampled through a tether system, preventing any disturbances due to human contact the day of an experiment. For all infusion rates ACTH baselines were less than or equal to 55 +/- 17 pg/ml, and cortisol baselines were less than or equal to 6 +/- 3 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Corticotropin responses to hypoglycemia and hypotension during ovine pregnancy

1994 ◽  
Vol 266 (1) ◽  
pp. R180-R187
Author(s):  
M. Keller-Wood
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Regular Insulin ◽  
Plasma Acth ◽  
Specific Effects ◽  
Arterial Blood ◽  
Multiple Stimulus ◽  
The Mean ◽  
Pregnant State ◽  
The Right ◽  
Pituitary Adrenal Axis

The adrenocorticotropic hormone (ACTH) responses to hypoglycemia and to hypotension were compared in pregnant and nonpregnant ewes. In the first study pregnant and nonpregnant ewes were each subjected to hypoglycemia induced by injection of 0.05, 0.10, or 0.25 U regular insulin/kg body wt or to saline infused as a control. In the second study pregnant and nonpregnant ewes were subjected to hypotension induced by the infusion of 2.5, 5.0, or 10.0 micrograms nitroprusside.kg-1.min-1 or to dextrose infused as a control. ACTH responses to hypoglycemia were significantly increased in the pregnant ewes, and the relation between plasma glucose and plasma ACTH was shifted to the right, indicating greater ACTH responses for a given level of hypoglycemia in the pregnant state. The mean ACTH response to infusion of nitroprusside was reduced during pregnancy, despite significantly lower mean arterial blood pressure in the pregnant ewes. When the relation between mean arterial pressure and ACTH was compared in the two groups of ewes, the relation was significantly shifted to the left in the pregnant ewes, indicating lower ACTH responses to a given level of pressure during pregnancy. The results suggest that pregnancy does not uniformly alter ACTH responses to stimuli, suggesting multiple, stimulus-specific effects of pregnancy on the hypothalamo-pituitary-adrenal axis.

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