Patterns of serum cortisol levels in ovariectomized females with and without androgen administration.

Serum cortisol levels in humans and primates display a circadian rhythm. A study in monkeys showed that orchiectomy abolishes this circadian rhythm. The present study compared the patterns of serum cortisol levels between 9 a. m. and 3 p. m. in two groups of ovariectomized females, one treated with testosterone (T) and one without sex steroid administration. Over the first 80 minutes of the sampling period cortisol levels declined similarly in both groups, probably due to waning of stress of the experiment. Thereafter, levels fell further in the T-administered group, but not in the group without sex steroid administration. From this pilot study it is tentatively concluded that ovariectomy, in analogy with orchiectomy in monkeys, produces a loss of a circadian pattern of cortisol levels, which is reversed by administration of T. Furthermore, upon comparison of mean serum cortisol levels in the two groups, T appeared to have a suppressive effect on values of serum cortisol levels.     

Effects of handling and capture stress on plasma glucose, cortisol and androgen levels in brown trout, Salmo trutta morpha fario

The effects of two different catchin methods and one handling method on the plasma glucose, cortisol and androgens of brown trout ( Salmo trutta morpha fario ) were evaluated 2 minutes, 4 hours and 30 hours after capture. Plasma levels of glucose were influenced by stressing factors in both sexes; cortisol levels increased at different times in males, deending on the stressor, and immediately in all treatments in females. After handling, androgen titres showed a very sharp decline in both sexes, whereas with catching methods only male androgens were affected.

Zusammenfassung

Die Auswirkungen von Streß durch Handhabung und Fang der Bacbforelle (Salmo trutta morpha fario) auf Plasmaglucose, Cortisol und -androgen
Zur Untersuchun der Auswirkungen von zwei unterschiedlichen Fangmethoden und direktem Ergreifen mit der Hand auf die Bachforelle ( Salmo trutta morpba fario ) wurden die Werte für Glucose, Cortisol und Androgene im Plasma 2 Minuten, 4 Stunden und 30 Stunden nach dern Fang bestimmt. Die Glucosewerte im Plasma wurden bei beiden Geschlechtern durch Streßfaktoren beeinflußt. Die Cortisolwerte stiegen bei den Männchen je nach Streßfaktor nach verschiedenen Zeiten an, bei den Weibchen bei allen Faktoren sofort. Bei den Androgenwerten war bei beiden Geschlechtern nach Anfassen (mit der Hand) ein deutlicher Rückgang zu verzeichnen, während sich die Anwendung von Fanggeräten nur auf die Androgene der Männchen ausgewirkt hat.     

Suppression of basal plasma cortisol and adrenal androgen concentrations, but not of ACTH and cortisol responses to hCRH by low-dose dexamethasone in rhesus monkeys

Glucocorticoid treatment at replacement doses does not result in a suppression of ACTH and cortisol responses to corticotropin-releasing hormone (CRH), while basal plasma concentrations of cortisol and adrenal androgens are efficiently suppressed 34 h after starting treatment. This finding could be demonstrated in rhesus monkeys receiving a continuous infusion of dexamethasone (1 microgram/kg per h) for 48 h and confirms our observations in patients on alternate-day prednisone therapy and in patients with congenital adrenal hyperplasia on glucocorticoid replacement therapy. We conclude that the decrease of basal adrenal steroid secretion resulting from glucocorticoid replacement therapy represents an effect on hypothalamic rather than on pituitary function.     

Mechanism of dissociation of cortisol and adrenal androgen secretion after removal of adrenocortical adenoma in patients with Cushing's syndrome

We investigated the mechanism of dissociation of cortisol and dehydroepiandrosterone sulfate (DHEA-S) secretion by the adrenal glands after the removal of an adrenal gland containing an adrenocortical adenoma in a patient with Cushing's syndrome. After removal of the adrenocortical adenoma, the serum cortisol rapidly decreased from 24.6 +/- 6.4 micrograms/dl (mean +/- SD, n = 6) to 0.7 +/- 0.5 micrograms/dl. Serum DHEA-S levels were 15 +/- 14 micrograms/dl and 6 +/- 9 micrograms/dl before and after surgery, respectively, and significantly lower than the control values. Serum cortisol levels reverted to normal levels 1.5 to 3 years after the surgery. On the other hand, DHEA-S levels reverted to normal 5 to 7 years after the serum cortisol levels had normalized. Monolayer cultures of normal human adrenal cells obtained at adrenalectomy in patients with advanced breast cancer and atrophic adrenal cells adjacent to the adrenocortical adenoma in patients with Cushing's syndrome were used to study the mechanism of the dissociation of cortisol and DHEA-S secretion. ACTH caused significant increases in the productions of pregnenolone (P5), progesterone (P4), 17-hydroxypregnenolone (17-OH-P5), 17-hydroxyprogesterone (17-OH-P4), DHEA, DHEA-S, androstenedione (delta 4-A), and cortisol. The amounts of 17-OH-P5 and 17-OH-P4 produced by ACTH in atrophic adrenal cells were significantly greater than those in normal adrenal cells. The amounts of DHEA, DHEA-S and delta 4-A produced by ACTH in atrophic adrenal cells were significantly smaller than those of normal adrenal cells. The conversion rate of 17-OH-[3H]P5 to 17-OH-[3H]P4 and 11-deoxy-[3H] cortisol was higher in atrophic adrenal cells than in normal adrenal cells, but the conversion rate to [3H]DHEA, [3H]DHEA-S and [3H]delta 4-A was significantly lower in atrophic adrenal cells than in normal adrenal cells. These results suggest that the dissociation of cortisol from DHEA-S after the removal of adrenocortical adenoma is a probably due to diminished C17,20-lyase activity in the remaining atrophic adrenal gland.     

Dissociation of cortisol and behavioral indicators of stress in an orangutan (Pongo pygmaeus) during a computerized task

Computerized testing can induce behavioral signs of frustration in apes. Three variations of a computer task were used to investigate the effects of inter-trial intervals and rate of cursor movement on frustrative behavior and cortisol in an orangutan. Behaviors were recorded during test sessions, and saliva was collected immediately after test sessions for cortisol assay. Behavioral results indicated that extended (20 sec) periods of delay between trials induced signs of frustration in the subject, including forceful manual manipulation of objects and self-scratching. However, cortisol results indicated that Hypothalamic-Pituitary-Adrenal (HPA) axis activity was not induced by task performance. Rather, cortisol levels were reduced during performance of computer tasks compared to baseline levels. Findings from this study suggest that behavioral and cortisol responses to stress induced by performance of computer testing can become dissociated. This study validates salivary cortisol as a measure of HPA activity in apes and demonstrates a normal circadian rhythm of cortisol release in an orangutan.     

Immunoperoxidase stains cortisol in adrenal and pituitary.

The unlabeled peroxidase-anti-peroxidase (PAP) method of Sternberger was used to localize cortisol within paraffin embedded sections of cat adrenal and pituitary tissue. Incubation of the cortisol antiserum used in this method with increasing concentrations of cortisol led to progressive extinction of cortisol staining of the adrenal fasciculata cells, (as measured with a scanning integrating microdensitometer). This result suggests strongly that the staining achieved with this method was specific for cortisol. Cortisol staining was demonstrated not only within cells that synthesize cortisol (the adrenal fasciculata) but also in cells of the adrenal medulla and of the anterior pituitary, two target sites for cortisol action.     

Effects of hypophysectomy and immobilization stress on S-adenosylmethionine levels in rat adrenal glands

Rat adrenal S-adenosylmethionine (SAM) levels and phenylethanolamine-N-methyltransferase (PNMT) activity were measured under conditions of hypophysectomy and stress. A new dual-label radioenzymatic assay for SAM is presented which eliminates problems found to exist with previous methods. Strain-specific differences in both PNMT and SAM were found, as well as sex differences in SAM levels. Immobilization stress resulted in an increase in adrenal SAM and PNMT activity, while hypophysectomy decreased both. The distribution of SAM between cortex and medulla did not change with either hypophysectomy or stress. Hypophysectomized Fisher rats were found to be capable of increasing PNMT activity in the absence of increased SAM levels.     

Acute psychological stress increases plasma levels of cortisol, prolactin and TSH.

The effects of acute stress during a parachute jump on hormonal responses were studied in 12 experienced and 11 inexperienced military parachutists. Each subject performed two jumps. Prior to and immediately after each jump blood samples were drawn and analysed for plasma levels of cortisol, prolactin, thyrotropin (TSH), somatotropin (STH), and luteinizing hormone (LH). While there was a significant increase in cortisol, prolactin and TSH levels after both jumps, no alterations could be observed in STH and LH levels. Stress-induced hormonal responses were not affected by jump experience. There was also no association between the endocrine variables and anxiety scores.     

Effect of myiasis and acute restraint stress on plasma levels of immunoreactive beta-endorphin, adrenocorticotrophin (ACTH) and cortisol in the sheep

Cutaneous myiasis in sheep arising from the activity of Lucilia cuprina larvae can result in significant physiological changes in susceptible animals. The stress imposed on the pituitary-adrenal axis of the sheep in response to myiasis and acute restraint is the subject of this investigation. Merino wethers were exposed to handling restraint, and blood sampling, during examination for blowfly strike; where necessary, they were treated for cutaneous myiasis. Significant changes in the plasma concentrations of immunoreactive beta-endorphin (beta-EP), ACTH and cortisol were found in sheep with extensive myiasis, as compared with unstruck sheep or those with only localized myiasis. In five susceptible sheep with extensive cutaneous myiasis, mean plasma levels of beta-EP, ACTH and cortisol were 307 +/- 71 pg ml-1, 953 +/- 58 pg ml-1 and 232 +/- 46 nmol l-1 respectively, compared with 818 +/- 89 pg ml-1, 641 +/- 41 pg ml-1 and 107 +/- 17 nmol l-1 in six unstruck sheep handled similarly. Whereas significant increases in plasma ACTH and cortisol can result from pituitary-adrenal responses to acute emotional or surgical stress, and are usually accompanied by a concomitant release of beta-EP from the pituitary, the present findings indicate a marked reduction in beta-EP levels and a significant increase in ACTH and cortisol in sheep following blowfly strike and acute handling restraint. This result suggests that cutaneous myiasis in susceptible sheep can alter the pituitary-adrenal response to acute restraint stress, and this could occur either by an alteration of precursor processing in the pituitary or by the selective release of ACTH.     

Ether stress increases adrenomedullin gene expression and levels in the rat adrenal.

To study the contribution of adrenomedullin in the adrenal medulla in the stress response, we measured plasma and adrenal levels of adrenomedullin in sham-operated (intact) rats and in rats without adrenal medulla, with or without exposure to ether vapor for 15 min. Adrenomedullin levels decreased drastically after demedullation. Effect stress resulted in increased adrenomedullin levels in both adrenal and plasma in sham-operated rats, but not in demedullated rats. The responses of plasma adrenocorticotropin to stress were similar, but the elevations in plasma corticosterone levels were significantly less in demedullated rats. In the sham-operated rat, preproadrenomedullin mRNA levels were increased after stress, and this effect was not blocked by pretreatment with hexamethonium. We conclude that stress increases adrenomedullin synthesis and secretion from the adrenal medulla through a hexamethonium-insensitive mechanism, and that adrenomedullin release from the adrenal medulla may play a role in cortical steroidogenesis.     

Baseline and stress levels of cortisol in conscious and unrestrained Japanese macaques (Macaca fuscata)

A vest and tethering system was applied to Japanese macaques (Macaca fuscata) to collect blood samples under less stressful conditions. The level of plasma cortisol was assayed to assess the amount of stress. The pattern of plasma cortisol fluctuation during 24 hours was consistent under non-stress conditions. The plasma cortisol level was increased significantly by encounter and venipuncture. The increase was especially noteworthy when the experimental macaques encountered a large adult male, reflecting the strong stress on macaques. As venipuncture is a common medical procedure, and the encounter between macaques who have never met before occurs frequently, this vest and tethering system is useful for the assessment of the amount of stress in the daily care of macaques in a laboratory.     

Dissociation of plasma cortisol and ACTH responses to dexamethasone in healthy subjects

We examined the plasma cortisol and ACTH concentrations after graded doses of dexamethasone in a group of young, healthy adults. The decrease in cortisol was uniform in all subjects, and in 8 subjects there was a high degree of correspondence with the plasma ACTH concentration. The remaining 5 subjects had no change in plasma ACTH concentration during dexamethasone administration. All subjects had an expected diurnal change in cortisol on 2 pretreatment days and there was a corresponding diurnal change in ACTH for those subjects who had associated ACTH and cortisol responses after dexamethasone, while those with dissociated ACTH and cortisol after dexamethasone had no diurnal ACTH pattern. These findings were consistent with the 24-hour pattern of ACTH and cortisol before and after 1.0 mg of dexamethasone in 2 of the same subjects. These results are further evidence for ACTH independent regulation of adrenal function and indicate that pituitary-adrenal regulation in man is more complex than the traditional model of ACTH-cortisol feedback would predict.     

Unilateral orchidectomy of ram lambs: acute, chronic and hCG-stimulated androgen levels

1. The objectives of this study were to determine whether compensation of androgen secretion occurred acutely, chronically or after hCG-stimulation in unilaterally orchidectomized (ULO) rams. 2. Testosterone (T) concentrations were not significantly different (P greater than 0.10) between ULO and sham-operated ram lambs during the period immediately following ULO. 3. Chronically, testosterone concentrations were not significantly different (P greater than 0.10) between ULO and sham-operated ram lambs. 4. After hCG injection, the testosterone response of chronic ULO ram lambs was approx. half the response of the sham-operated ram lambs. 5. These data indicate that a rapid and sustained compensatory response of basal secretion of testosterone but not hCG-inducible testosterone secretion occurred in the ULO'd ram lambs.     

Characterization of adrenal ACTH signaling pathway and steroidogenic enzymes in Erhualian and Pietrain pigs with different plasma cortisol levels

Our previous study demonstrated significant difference in the basal plasma cortisol levels between Erhualian (EHL) and Pietrain (PIE) pigs, implicating fundamental breed difference in adrenocortical function. The objectives of the present study were therefore to characterize the expression pattern of proteins involved in adrenal ACTH signaling and, including melanocortin type 2 receptor (MC2R), cAMP response element binding protein (CREB) and phosphorylated CREB (pCREB), steroidogenic acute regulatory protein (StAR), as well as that of the key enzymes involved in steroidogenesis in EHL and PIE pigs, in association with the plasma corticotrophin (ACTH) and cortisol levels. The plasma concentrations of the substrates for adrenal steroidogenesis, cholesterol and low-density lipoprotein (LDL) cholesterol, did not differ between breeds. Plasma concentration of ACTH and the adrenal contents of MC2R mRNA and protein were similar in two breeds of pigs, whereas the basal plasma concentrations of cortisol in EHL pigs were 1.5 folds higher than that in PIE pigs. The higher basal plasma cortisol levels in EHL pigs were found to be accompanied with the higher expression of ACTH post-receptor signaling components, cAMP, pCREB and StAR, as well as the higher expression of cholesterol side-chain cleavage cytochrome P450 (P450scc), 17alpha-hydroxylase cytochrome P450 (P450(17alpha)), 21-hydroxylase cytochrome P450 (P450c21) and 11beta-hydroxylase cytochrome P450 (P450(11beta)). These results indicated that the enhanced cAMP/PKA/pCREB-signaling system and augmented expression of StAR and steroidogenic enzymes are major attributes to the higher basal plasma cortisol concentrations in pigs.     

Influence of estradiol on adrenal activity in ovariectomized cows during acute stress

Stress-dependent activation of the hypothalamo-pituitary-adrenal axis (HPA) can compromise reproductive function in animals and humans. In addition, it has been shown that estrogens are also capable of influencing the activity of the adrenal cortex. The objective of this study was to evaluate the effect of estradiol (E2) on adrenocortical secretion of cortisol and progesterone as well as on pituitary LH-release in cows during stress. Five ovariectomized Brown Swiss cows were exposed to acute restraint stress (2-h immobilization in a trimming chute), either with or without E2 treatment. Blood samples were taken every 15 min during a 5-h period for determination of cortisol progesterone and LH. Our results demonstrate that during the 2-h stress period mean cortisol concentrations significantly (P < 0.05) increased in all cows independent of E2 treatment. Mean progesterone concentrations also increased during stress, but the effect was only significant in E2-untreated cows. In contrast to cortisol and progesterone, mean LH values decreased in all animals during stress, but the decline was not significant. However, significantly lower mean LH values were seen at the end of the stress period comparing to values before stress. In cows without stress, E2 treatment had no significant effect on mean values of all three hormones analyzed. From our results it can be concluded that in ovariectomized cows (a) acute stress increases cortisol and progesterone secretion but decreases LH release and (b) the stress induced adrenocortical and pituitary responses were clearly attenuated under the influence of estradiol.     

Dissociation of aldosterone and prostaglandin biosynthesis in the rat adrenal glomerulosa

The relationship between aldosterone production and prosta-glandin E2 synthesis was evaluated using the responses of isolated rat adrenal glomerulosa cells to angiotensin II, ACTH and potassium. Simultaneous PGE2 and aldosterone measurements were made during timed incubations with these stimuli, and in incubations with arachidonic acid, meclofenamate, indomethacin, and aminoglutethamide. PGE2 and aldosterone production were assessed by radioimmunoassay. We were not able to demonstrate stimulation of PGE2 by angiotensin II, ACTH, or potassium despite significant increments in aldosterone production with these stimuli. Arachidonic acid enhanced PGE2 synthesis, but had no effect on aldosterone realease. Indomethacin and meclofenamate inhibited aldosterone secretion. Aminoglutethimide depressed aldosterone production, but had little effect on PGE2 levels in the media. These studies demonstrate that dienoic prostaglandins play no direct role in aldosterone production stimulated by angiotensin II, ACTH, or potassium in rat adrenal glomerulosa cells. Since inhibitors of cyclo-oxygenase decreased aldosterone synthesis, it is possible that fatty acids other than arachidonic acid may be cyclo-oxygenated to products which regulate aldosterone production.     

Dissociation of aldosterone and prostaglandin biosynthesis in the rat adrenal glomerulosa

The relationship between aldosterone production and prostaglandin E₂ synthesis was evaluated using the responses of isolated rat adrenal glomerulosa cells to angiotensin II, ACTH and potassium. Simultaneous PGE₂ and aldosterone measurements were made during timed incubations with these stimuli, and in incubations with arachidonic acid, meclofenamate, indomethacin, and aminoglutethamide. PGE₂ and aldosterone production were assessed by radioimmunoassay. We were not able to demonstrate stimulation of PGE₂ by angiotensin II, ACTH, or potassium despite significant increments in aldosterone production with these stimuli. Arachidonic acid enhanced PGE₂ synthesis, but had no effect on aldosterone release. Indomethacin and meclofenamate inhibited aldosterone secretion. Aminoglutethimide depressed aldosterone production, but had little effect on PGE₂ levels in the media.These studies demonstrate that dienoic prostaglandins play no direct role in aldosterone production stimulated by angiotensin II, ACTH, or potassium in rat adrenal glomerulosa cells. Since inhibitors of cyclo-oxygenase decreased aldosterone synthesis, it is possible that fatty acids other than arachidonic acid may be cyclo-oxygenated to products which regulate aldosterone production.     

Inhibition of cortisol production in isolated guinea-pig adrenal cells

Cortisol, added to 1 ml incubation medium containing 3-4 X 10(5) isolated guinea-pig adrenal cells, provoked a decrease in basal and ACTH (250 pg)-stimulated cortisol production, in correlation with the amounts used (50 ng-2,000 ng). A decrease in aldosterone production could be seen when cortisol concentrations reached or exceeded 1,000 ng/ml. There were no variations in either androgens (delta 4-androstenedione, dehydropiandrosterone) or 17-hydroxyprogesterone. Only 11-deoxycortisol was slightly increased. Using increasing concentrations of ACTH (50-250 pg), both in the absence and in the presence of 1,000 ng cortisol, it was noted that the inhibition induced by cortisol was of a competitive type and could be overcome by ACTH. This decrease in cortisol was concomitant with an increase in 11-deoxycortisol. Neither corticosterone nor dexamethasone reduced cortisol production. In addition, it was shown that the conversion of tritiated 11-deoxycortisol to radioactive cortisol increased significantly under the influence of 250 pg ACTH (mean relative variation of 21.7% +/- 7.7 (SEM), n = 6, P less than 0.05); but decreased significantly under the combined effect of 1,000 ng exogenous cortisol and the same dose of ACTH: (mean relative variation of 4.3% +/- 1 (SEM), n = 8, P less than 0.005). There is therefore reason to believe that the concentrations of cortisol at the adrenal level modulate the stimulation induced by ACTH and that this self-adjustment forms part of the control mechanisms involved in corticosteroidogenesis.