Effects of exogenous melatonin on human pituitary and adrenal secretions. Hormonal responses to specific stimuli after acute administration of different doses at two opposite circadian stages in men

We evaluated the effect of an acute oral administration of 2 dosages (100 and 1 mg) of melatonin (MT) vs placebo (PL) on pituitary release of LH, FSH, TSH and PRL after GnRH + TRH and on the adrenocortical release of cortisol, aldosterone and progesterone after ACTH in healthy adult males. We carried out a double blind study on 6 volunteers in winter-early spring, at 2 opposite phases of the circadian cycle: 08(00) and 20(00). Injection of GnRH (100 micrograms), TRH (200 micrograms) and ACTH (10 micrograms of the synthetic analogue ACTH 1-17, alsactide) was performed 1 h after MT or PL ingestion. The measurement of plasma MT levels confirmed its effective gastrointestinal absorption after both doses. The hormonal patterns were superimposable after MT and PL. A higher response of FSH, PRL, cortisol and aldosterone was observed in the evening vs morning protocols independently of previous treatment (MT or PL). Our data demonstrate that the acute oral administration of 2 different doses of MT at 2 opposite circadian stages is ineffective as to the modification of a variety of pituitary and adrenocortical responses in human male subjects. The circadian chronosusceptibility of pituitary and adrenocortical cells to specific stimuli deserves interest to future investigation.     

Effects of a long-acting somatostatin analogue on pituitary-adrenocortical secretion in normal human subjects

A potent and long-acting somatostatin analogue, SMS 201-995 (SMS) is currently employed for the treatment of various diseases with hypersecretion of hormones such as acromegaly and gastrinoma. The suppressive effects of SMS are also reported on the other pituitary and gastrointestinal hormones. The corticotropic-adrenocortical axis is a crucial hormonal complex in maintaining normal activity and life itself. In this study, the effects of SMS on corticotropic-adrenocortical functions were studied, since the effects of SMS on this hormonal axis are not well established. Seven normal males received a sc injection of 100 micrograms SMS or placebo at 0830 h and 100 micrograms synthetic human corticotropin-releasing hormone (hCRH) intravenously (SMS-hCRH study). Five of the 7 subjects were given an injection of a synthetic (1-24) ACTH (250 micrograms or 63 micrograms) at 0900 h after 100 micrograms SMS or a placebo at 0830 h (SMS-ACTH study). Blood samples were drawn at -30, 0, 15, 30, 60, 90 and 120 min after the hCRH injection for the determination of ACTH and cortisol in the SMS-hCRH study, and cortisol and aldosterone in the SMS-ACTH study. Although significant rises in plasma ACTH and cortisol levels were observed regardless of the preinjection of SMS, their responses to hCRH were significantly lower with the pretreatment with SMS than without SMS. A significant increase in plasma cortisol and aldosterone was observed in response to synthetic ACTH with both ACTH alone and the combined administration of SMS and ACTH, at either dose of ACTH. However, no significant difference in cortisol and aldosterone secretion was detected with and without SMS.(ABSTRACT TRUNCATED AT 250 WORDS)     

Responses of plasma adrenocorticotropin and cortisol to intravenous injection of synthetic ovine corticotropin releasing factor in the morning and early evening in normal human subjects

This study was designed to compare the responsiveness of adrenocorticotropin (ACTH) and cortisol secretion to corticotropin-releasing factor (CRF) in the morning and early evening in normal human subjects. Synthetic ovine CRF (1.0 micrograms/kg) or normal saline, was administered as an i.v. bolus injection to six normal males at 900 h and 1700 h. Blood samples were obtained before and 15, 30, 60, 90 and 120 min after CRF or saline injection. Significant increases in plasma ACTH and cortisol levels were observed in all subjects at the both time of testing after CRF injection. The net increments in the areas under the concentration curve (areas in the CRF experiment minus those in the saline control experiment) were not statistically different for both ACTH (mean +/- SEM: 41.0 +/- 10.6 pg/ml h in the morning: 51.1 +/- 8.9 pg/ml h in the evening) and cortisol (mean +/- SEM: 28.5 +/- 5.0 micrograms/dl h in the morning; 36.2 +/- 4.0 micrograms/dl h in the evening). Also no significant difference was observed in net increment, peak level and the ratio of peak level to the basal level of ACTH and cortisol after CRF injection. There were no appreciable changes in plasma concentrations of growth hormone, thyroid-stimulating hormone or prolactin, although slight but statistically significant rises in plasma levels of luteinizing hormone and follicle-stimulating hormone were observed. These results suggest that there is no significant difference in responsiveness of the pituitary-adrenal axis to CRF in the morning (900 h) and early evening (1700 h), and thus the time of day will not necessarily have to be considered when CRF is used between these times in a clinical test to evaluate pituitary ACTH reserve.     

Intranasal administration of ACTH(1-24) stimulates catecholamine secretion.

Previously, we reported that intranasal (IN) ACTH(1-24) administration stimulates adrenocortical steroid secretion in normal subjects. To determine the efficiency of transmucosal absorption of ACTH into the adrenal medulla, we measured serum cortisol, aldosterone, epinephrine, norepinephrine and dopamine levels after IN vs. intravenous (IV) administration of 250 microg ACTH(1-24) in 7 healthy adult men (mean age 21.7 +/- 1.2 yr; range, 21 - 24 yr). Blood was collected at 0, 30, 60 and 120 min after administration of ACTH(1-24), and the levels of adrenocortical steroids and catecholamines were measured by specific RIA and HPLC methods, respectively. There were no side effects associated with IN or IV ACTH administration. Consistent with the previous study, serum cortisol and aldosterone increased after IN administration of ACTH(1-24), peaking 30 min after administration. Sixty minutes after IN and IV administration of ACTH, epinephrine levels increased by 41.9 +/- 13.1 % and 63.3 +/- 11.8 %, respectively, and remained elevated throughout the sampling period. Thirty minutes after IN or IV administration of ACTH(1-24), plasma norepinephrine levels increased by 55.9 +/- 13.4 % and 73.7 +/- 15.0 %, respectively, peaking 30 min after ACTH(1-24) administration, and decreasing to basal levels within 60 min. Plasma dopamine levels did not change after IN administration of ACTH(1-24). Adrenocortical steroid and catecholamine levels did not increase after IN administration of saline. These results demonstrate that IN administration of ACTH(1-24) not only stimulates adrenocortical steroids, but also epinephrine and norepinephrine.     

Atrial natriuretic factor inhibits the CRH-stimulated secretion of ACTH and cortisol in man.

Corticotrophic secretion of ACTH is stimulated by corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP), and suppressed by glucocorticoids. In vitro and preclinical studies suggest that atrial natriuretic factor (ANF) may be a peptidergic inhibitor of pituitary-adrenocortical activity. The aim of this study was to elucidate a possible role of ANF as a modulator of ACTH release in humans. A bolus injection of 100 micrograms human CRH (hCRH) during a 30 min intravenous infusion of 5 micrograms/min human alpha atrial natriuretic factor (h alpha ANF) was administered at 19:00 to six healthy male volunteers. In comparison to saline, a blunted CRH-stimulated secretion of ACTH (mean maximum plasma level +/- SD 45 min after hCRH: saline 46.2 +/- 14.2 pg/ml, h alpha ANF 34.6 +/- 13.8 pg/ml, p-value = 0.007) and a delayed rise (10 min) in cortisol were detected. The maximum plasma cortisol levels remained nearly unchanged between saline and h alpha ANF administration (mean maximum plasma level +/- SD 60 min after hCRH: saline 182 +/- 26 ng/ml, h alpha ANF 166 +/- 54 ng/ml). No effects of h alpha ANF on basal cortisol levels were observed; in contrast, basal ACTH plasma levels were slightly reduced. Basal blood pressure and heart rate remained unaffected. In the control experiment, infusion of 3 IU AVP in the same experimental paradigm increased basal and stimulated ACTH and cortisol levels significantly in comparison to saline. These observations suggest that intravenously administered haANF inhibits the CRH-stimulated release of ACTH in man.     

18-oxocortisol: effect of dexamethasone, ACTH and sodium restriction

The urinary excretion of 18-oxocortisol in 37 normal subjects consuming a normal sodium diet was 1.2 +/- 0.9(SD) microgram/24 h. Dexamethasone administration to 5 normal individuals suppressed the excretion of 18-oxocortisol from 1.16 +/- 0.5 micrograms/24 h to 0.6 +/- 0.2 micrograms/24 h. While they still received dexamethasone, ACTH administration raised the 18-oxo-cortisol excretion to 3.82 +/- 1.2 micrograms/24 h. Seven normal subjects were placed on a sodium restricted diet, and the urinary excretion of 18-oxocortisol rose from 1.5 +/- 1.21 micrograms/24 h to 8.54 +/- 5.08 micrograms/24 h and aldosterone from 6.6 +/- 2.0 micrograms/24 h to 39.7 +/- 14.6 micrograms/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in all cases aldosterone increased with sodium restriction. The urinary excretion of 18-oxocortisol correlated significantly with the excretion of aldosterone, 18-hydroxycortisol, cortisol, and 19-nordeoxycorticosterone. These studies indicate that 18-oxocortisol secretion is under ACTH regulation, but since sodium restriction also increases the excretion of 18-oxocortisol, the renin-angiotensin system must also participate in its regulation. However, some individuals do not increase their excretion of 18-oxocortisol with sodium restriction, although aldosterone excretion increases as expected, suggesting that additional factors participate in the regulation of 18-oxocortisol production.     

Diurnal rhythm of plasma immunoreactive corticotropin-releasing factor in normal subjects

Plasma corticotropin-releasing factor (CRF), corticotropin (ACTH) and cortisol levels were simultaneously determined by radioimmunoassays at 0600 h, 1200 h, 1800 h and 2200 h in six normal subjects, in order to examine whether the diurnal rhythm in plasma CRF exists and how it correlates to the diurnal rhythm in plasma ACTH and cortisol concentration. The highest CRF level was observed at 0600 h (7.0 +/- 1.2 pg/ml) and significantly lower levels (p less than 0.01) at 1800 h (1.7 +/- 0.2 pg/ml) and 2200 h (1.9 +/- 0.4 pg/ml). A clear diurnal rhythm was demonstrated in plasma ACTH and cortisol levels, with the highest values at 0600 h (44.6 +/- 8.1 pg/ml and 15.9 +/- 2.0 micrograms/dl, respectively) and the lowest at 2200 h (12.3 +/- 2.8 pg/ml and 4.6 +/- 1.0 micrograms/ml, respectively). These results suggest that the diurnal rhythm in ACTH and cortisol is under the regulation, at least in part, of the diurnal rhythm in CRF secretion.     

Basal plasma aldosterone levels and tetracosactid-induced increase of aldosterone secretion in conscious male rabbits: lack of correlation with glucocorticosteroid levels

The adrenocortical secretory activity under basal conditions and after treatment with tetracosactid (1-24ACTH) has been investigated in chronically cannulated male rabbits. Basal plasma concentrations of glucocorticosteroids (0.74 micrograms/100 ml) and aldosterone (78 pg/ml) have been determined in a greater number of animals. No significant positive correlation between basal glucocorticosteroid and aldosterone plasma levels could be found. After intravenous injection of 2.5, 5.0, 10.0 and 20.0 micrograms/kg body weight tetracosactid glucocorticosteroid concentrations were significantly elevated between 40--100 min after administration; aldosterone release, on the other hand, was significantly increased only after injection of 10.0 or 20.0 micrograms/kg body weight tetracosactid between 20--60 min after injection. After administration of high tetracosactid doses glucocorticosteroid and aldosterone plasma concentrations were significantly correlated (10.0 micrograms/kg: r = 0.62; 20.0 micrograms/kg: r = 0.26). Because of the relative insensitivity of the zona glomerulosa cells to tetracosactid administered intravenously, it is concluded that ACTH is only of minor importance in the regulation of aldosterone secretion in the rabbit.     

Steroid biosynthesis by zona glomerulosa-fasciculata cells in primary culture of guinea-pig adrenals

Steroidogenesis was studied in guinea-pig glomerulosa-fasciculata cells maintained in primary culture for up to 7 days. The basal secretion which remained stable for the first 2 days in culture rapidly rose to reach a plateau on day 4 at levels 6-7-fold higher than those observed during the first 2 days of culture while the maximal response to ACTH in terms of cortisol and androstenedione secretion was fairly stable throughout the 7-day period. Exposure of glomerulosa-fasciculata cells to ACTH caused a stimulation of pregnenolone, 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, corticosterone, 11-deoxy-corticosterone, 11-deoxycortisol, cortisol, dehydroepiandrosterone, androstenedione, 11 beta-hydroxyandrostenedione and aldosterone while, after 48 h of incubation, a marked accumulation of end-products, namely cortisol and 11 beta-hydroxyandrostenedione, was observed. The half-maximal steroidogenic response to ACTH occurred at concentrations varying between 1.7 x 10(-11) and 1.1 x 10(-10) mol/l for the 12 steroids examined. Addition of 8-bromoadenosine 3', 5'-cyclic monophosphate stimulated steroid secretion in a dose-dependent manner. Maximal response to 8-bromoadenosine 3', 5'-cyclic monophosphate was obtained at 1 mmol/l, and no further rise of steroid secretion was observed after addition of ACTH. Incubation of glomerulosa-fasciculata cells with labeled corticosterone, cortisol and androstenedione indicates that only androstenedione can be converted into 11 beta-hydroxyandrostenedione, thus suggesting that this end-product is a good parameter of the C-19 steroid production by guinea-pig glomerulosa-fasciculata cells in primary culture. The present data confirm that guinea-pig glomerulosa-fasciculata cells in primary culture provide an interesting model for the study of the regulation of C-19 steroid formation by the adrenals.     

Adrenocortical responsiveness to the synthetic ACTH 1-17 analogue given at different circadian stages

The study concerns the adrenocortical glucocorticoid responsiveness to the ACTH 1-17 analogue given at different times of the day, namely near to the zenith and the nadir of the circadian curve of plasma cortisol. Two schedules of administration of the heptadecapeptide have been performed: a pulse i.v. injection of 4 microgram; b. i.m. injection of 100 microgram. Both the doses were given to the same subject in the morning and in the evening of different days. The chrono-sensitivity of the adrenal cortex to ACTH 1.17 analogue is well evident after pulse stimulation by a micro-dose of the heptadecapeptide; in fact the plasma cortisol increase from basal values is significantly higher in evening than in the morning (p less than 0.001). The cortico-stimulatory effect of the higher dose of ACTH 1.17 analogue lasts about 12 h. and then plasma and urinary glucocorticoids take the usual circadian pattern again.     

Adrenal-pituitary-gonadal relationships and ejaculate characteristics in captive leopards (Panthera pardus kotiya) isolated on the island of Sri Lanka

In Study 1, semen was collected using a standardized electroejaculation procedure. Males (N = 8) produced ejaculates with a high incidence of sperm abnormalities (77 +/- 3.3%). After electroejaculation under anaesthesia, serum cortisol concentrations increased (P less than 0.05), while testosterone concentrations decreased (P less than 0.05) and LH and FSH concentrations were unchanged (P less than 0.05) over a 2-h bleeding period. In Study 2, male and female leopards were bled at 5-min intervals for 3 h and given (i.v.): (1) saline (N = 2/sex); (2) GnRH (1 microgram/kg body weight) 30 min after the onset of sampling (N = 5/sex); or (3) ACTH (250 micrograms) at 30 min followed by GnRH 1 h later (N = 5/sex). Basal concentrations of serum LH, FSH and cortisol were comparable (P greater than 0.05) between male and female leopards. After GnRH, peak LH concentrations were 2-fold greater (P less than 0.05) in males than females while FSH responses were similar. In males, testosterone concentrations increased 2-3-fold following GnRH. After ACTH, serum cortisol concentrations doubled within 15 min in both sexes. Administration of ACTH 1 h before GnRH did not affect GnRH-induced LH or FSH release (P greater than 0.05); however, testosterone secretion was only 30% of that observed after GnRH alone (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ability of cortisol and progesterone to mediate the stimulatory effect of adrenocorticotropic hormone upon testosterone production by the porcine testis

The influence of corticosteroids and progesterone upon porcine testicular testosterone production was investigated by administration of exogenous adrenocorticotropic hormone (ACTH), cortisol and progesterone, and by applying a specific stressor. Synthetic ACTH (10 micrograms/kg BW) increased (P less than 0.01) peripheral concentrations of testosterone to peak levels of 5.58 +/- 0.74 ng/ml by 90 min but had no effect upon levels of luteinizing hormone (LH). Concentrations of corticosteroids and progesterone also increased (P less than 0.01) to peak levels of 162.26 +/- 25.61 and 8.49 +/- 1.00 ng/ml by 135 and 90 min, respectively. Exogenous cortisol (1.5 mg X three doses every 5 min) had no effect upon circulating levels of either testosterone or LH, although peripheral concentrations of corticosteroids were elevated (P less than 0.01) to peak levels of 263.57 +/- 35.03 ng/ml by 10 min after first injection. Exogenous progesterone (50 micrograms X three doses every 5 min) had no effect upon circulating levels of either testosterone or LH, although concentrations of progesterone were elevated (P less than 0.01) to peak levels of 17.17 +/- 1.5 ng/ml by 15 min after first injection. Application of an acute stressor for 5 min increased (P less than 0.05) concentrations of corticosteroids and progesterone to peak levels of 121.32 +/- 12.63 and 1.87 +/- 0.29 ng/ml by 10 and 15 min, respectively. However, concentrations of testosterone were not significantly affected (P greater than 0.10). These results indicate that the increase in testicular testosterone production which occurs in boars following ACTH administration is not mediated by either cortisol or progesterone.     

Plasma glucocorticosteroid and aldosterone levels during physiological and stress conditions in rabbits. II. adult animals

The pattern of adrenal steroid secretion under basal and stress conditions and the response to tetracosactid (20.0 micrograms/kg body weight) were studied in adult male rabbits. In animals repeatedly stressed by artery puncture, plasma glucocorticosteroid levels were slightly higher than those found in unstressed control animals. The combined stress of repeated exposure to ether vapor for 60 sec, followed by artery puncture, significantly stimulated glucocorticosteroid release, concentrations progressively increasing with the number of ether exposures applied. A much faster and more pronounced stimulation of glucocorticosteroid release was seen in animals treated with 20.0 micrograms/kg body weight tetracosactid. Plasma aldosterone levels in animals stressed by artery puncture were higher, although not significantly, than those of unstressed control animals. Repeated exposure to ether vapor for 60 sec, followed by artery puncture, on the other hand slightly decreased plasma aldosterone concentrations. A strong stimulation of aldosterone release at 20--60 min after injection could be elicited only by intravenous administration of 20.0 micrograms/kg body weight tetracosactid. Because of the insensitivity of the zona glomerulosa cells to increased ACTH levels under stress conditions, it is concluded that ACTH is only of minor importance both under basal and stress conditions in the regulation of aldosterone secretion in the rabbit.     

Effect of cortisol or adrenocorticotropic hormone on luteinizing hormone secretion by pig pituitary cells in vitro

The effect of cortisol or adrenocorticotropic hormone (ACTH) on basal and gonadotropin-releasing hormone (GnRH)-induced secretion of luteinizing hormone (LH) was studied in vitro using dispersed pig pituitary cells. Pig pituitary cells were dispersed with collagenase and DNAase and then grown in McCoy's 5a medium containing 10% dextran charcoal-pretreated horse serum and 2.5% fetal calf serum for 3 days. Cells were preincubated with cortisol or ACTH before GnRH was added. When pituitary cells were incubated with 400 micrograms cortisol/ml medium for 6 h or longer, increase basal secretion of LH was observed. However, GnRH-induced LH release was reduced by cortisol. The degree of this reduction was dependent on cortisol, and a concentration of cortisol higher than 100 micrograms/ml was needed. Cortisol also inhibited the 17 beta-estradiol-induced increase in GnRH response. ACTH-(1-24), ACTH-(1-39), or porcine ACTH had no influence on GnRH-induced LH secretion. Our results show that cortisol can act directly on pig pituitary to inhibit both normal and estradiol-sensitized LH responsiveness to GnRH.     

Circadian variations and extraadrenal effect of ACTH on insulinemia in rabbit.

The present experiment was designed to study the action of ACTH1-24 on insulin secretion during the circadian cycle in normal rabbits and to provide evidence that ACTH1-24 has an extra-adrenal effect on this secretion. In normal rabbits intravenous administration of three doses of ACTH1-24 (1, 10, 100 micrograms/kg) at 10 a. m. increased plasma insulin levels. Hyperglycemia only occurred with doses of 10 and 100 micrograms/kg. A maximum insulin response was already obtained at 1 micrograms/kg. The same experiment performed at 12 p. m. also induced hyperinsulinemia which was only noted at 10 and 100 micrograms/kg; hyperglycemia was only observed after stimulation by the highest dose (100 micrograms/kg). ACTH was therefore more effective during the day; however, at 12 p. m. plasma insulin levels were the highest, but only with the maximum dose of ACTH (100 micrograms/kg). The effect of ACTH1-24 was evaluated throughout the day on normal and adrenalectomized rabbits. In normal animals injection of ACTH1-24 increased plasma glucose and insulin levels both together. In the contrary, in rabbits deprived of adrenal glands, ACTH1-24 induced high insulinemia along with hypoglycemia. We could, therefore, reasonably conclude that ACTH stimulates directly the pancreatic secretion of insulin.     

Clinical chronopharmacology of ACTH 1-17. II. Effects on plasma testosterone, plasma aldosterone, plasma and urinary electrolytes (K, Na, Ca and Mg)

The aim of the investigation was to study the effects of ACTH 1-17 on plasma testosterone, plasma aldosterone as well as on both plasma and urinary electrolytes (K, Na, Mg and Ca) in healthy young adult males with regard to the time (clock hours) at which this polypeptide was injected. Eight healthy adults (males from 28 to 30 years) volunteered for the study. The were synchronized with a diurnal activity from 0700 to midnight and a nocturnal rest. Each week, during 6 consecutive weeks (January 19 to February 25, 1980) a 3-day test was performed on Saturday, Sunday and Monday. On Sundays 3 control-tests and the 3 ACTH-tests were programmed during which either saline or 100 microgram ACTH 1-17 were injected i.m. at respectively 0700, 1400 and 2100. During each 3 day-test period (72 h) the urinary excretion of K, Na, Mg and Ca was determined every 4 h at fixed clock hours. In addition, on Sundays, venous blood was sampled prior to control or ACTH injections at respectively 0700, 1400 and 2100 and 20, 40, 60, 90, 120, 150 and 180 min thereafter. Plasma testosterone, aldosterone (radioimmunoassays) K, Na (flame photometry), Mg and Ca (photocolorimetric methods) were determined in the collected samples. Both conventional and cosinor methods were used for statistical analyses. The injection of ACTH at 0700 was followed by a clear and statistically significant rise of plasma testosterone. No change with regard to control occurred when ACTH was injected at either 1400 or at 2100. A statistically significant rise of plasma aldosterone was observed after each of the ACTH injections. However, the highest plasma aldosterone level was reached when ACTH was administered at 1400 and the lowest level at 2100. ACTH-induced changes in plasma electrolytes were either nil (for Na and Ca) or small (for K and Mg). A more or less important increase of urinary K occurred after the ACTH injection at each of the 3 considered times. The highest values of excreted K occurred after the injection of ACTH at 0700, without shift of the acrophase. In contrast, injections of ACTH at 1400 and 2100 induced a dramatic alteration of the K rhythms. ACTH induced an important fall in the Na urinary excretion. This fall was the greatest when ACTH was injected at 1400. Na rhythm alterations also occurred, particularly after ACTH injections at 2100. However, this effect was less pronounced after ACTH injection at 0700 than at other considered time points. The urinary amount of excreted Ca did not seem to be affected by ACTH. Rhythm alterations occurred after ACTH injections at 1400 and 2100. Peaks of plasma testosterone, plasma aldosterone as well as plasma cortisol (reported in a previous paper) resulting from ACTH stimulation coincided in time with the acrophase of the physiological circadian rhythm in plasma levels of these hormones...     

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.     

Baseline,diurnal variations,and stress-induced changes of stress hormones in three captive beluga whales,Delphinapterus leucas

Concentrations of plasma adrenocorticotropic hormone (ACTH), cortisol, and aldosterone were investigated in three adult beluga whales (Delphinapterus leucas), held in a large outdoor public aquarium exhibit. The purpose of this study was to evaluate resting concentrations of these hormones and associated diurnal variations with routine interactions and medical procedures. Resting blood samples were collected voluntarily from the ventral fluke veins at predetermined times of the day to evaluate diurnal changes in analyte concentrations. In addition, hematology and serum chemistry analyses were performed to monitor health status and evaluate changes related to physical exam procedures. Analogous sampling was conducted during out-of-water physical examinations and before and after wading-contact sessions (WCS). Baseline stress hormone concentrations (± SD) were as follows: plasma ACTH (8.41 ± 5.8 pg/mL), serum cortisol (1.80 ± 0.71 g/dL), and serum aldosterone (11.42 ± 5.5 pg/mL). Plasma ACTH and cortisol concentrations were consistently higher in early morning than evening, while aldosterone was higher in the evening. All stress-related hormones were significantly elevated during physical examination. Plasma ACTH concentrations were most increased, 5–10-fold, during physical examination, whereas cortisol and aldosterone showed 2–4-fold elevations. Stress response analytes measured during the WCS did not differ significantly from baseline concentrations.     

Mild adrenal 3 beta-hydroxysteroid dehydrogenase deficiency with hyperaldosteronism

The patient was admitted to our hospital at 19 and again at 22-yr of age for hirsutism and hypertension. Her baseline and ACTH-stimulated plasma 17-hydroxy pregnenolone, dehydroepiandrosterone and dehydroepiandrosterone sulfate were increased whereas plasma 17-hydroxy progesterone and androstenedione were normal and responded poorly to ACTH. Plasma deoxycorticosterone, corticosterone and cortisol baseline levels were normal, and they responded normally to ACTH. The plasma aldosterone concentration (PAC) was always high and responded well to ACTH, angiotensin III and furosemide-upright stimulation. However, plasma renin activity (PRA) was normal or slightly high, and responded normally to furosemide-upright stimulation and fluorohydrocortisone suppression. Dexamethasone (2 mg/day) for 1-2 weeks suppressed the androgens, cortisol and corticosterone levels. PRA and PAC were suppressed temporally, but PRA returned to normal and PAC to be a high level after 2 weeks of dexamethasone administration. Blood pressure was also reduced temporally but returned to a high level after 2 weeks of dexamethasone. These results indicate that primary aldosteronism and dexamethasone-suppressible hyperaldosteronism were not likely to be present, and unknown aldosterone stimulating factors which potentiated the action of endogenous angiotensin II or ACTH might be responsible for the hyperaldosteronism in this patient. We conclude that this patient had a mild and non-salt losing 3 beta-HSD deficiency in the zona reticularis with normal fasciculata and high glomerulosa function.     

Pressor inhibition of angiotensin-induced ACTH secretion

We investigated whether the pressor effects of systemically administered angiotensin II (AII) influence ACTH secretion. Adrenalectomized barbiturate-anesthetized mongrel dogs with constant low resting cortisol concentrations due to slow constant cortisol infusion received either bolus injections (2.5 micrograms kg-1) or 15-min i.v. infusions of a low dose (12.5 ng kg-1min-1) of AII during which blood samples were taken for ACTH and cortisol determinations. In sequential continuous experiments in each dog, blood pressure was allowed to increase in response to AII administration or was controlled by means of concurrent i.v. injections or infusions of the hypotensive drug papaverine, or by blood withdrawal from the vena cava. When the arterial pressure rise induced by AII was substantially attenuated or prevented by papaverine administration or blood withdrawal, mean ACTH secretion rates increased 400-800% and mean ACTH concentrations increased by 280-500%. On the other hand, AII administration alone caused large increases in mean arterial blood pressure but did not increase ACTH secretion significantly above control levels. These data suggest that when endogenous AII levels are elevated without a concurrent increase in blood pressure, as occurs during hypovolemia or sodium depletion, AII may have a significant influence on ACTH secretion.