Plasma and salivary 6beta-hydroxycortisol measurements for assessing adrenocortical activity in patients with adrenocortical adenomas.

The aim of this study was to examine and compare the potential usefulness of plasma and salivary 6beta-hydroxycortisol measurements for assessing adrenocortical activity in patients with adrenocortical adenomas. Plasma and salivary cortisol as well as 6beta-hydroxycortisol determinations were performed by radioimmunoassay after extraction with ethyl acetate followed by chromatographic separation using a modified paper chromatographic system. Samples were obtained from 36 control subjects and 37 patients with non-hyperfunctioning adrenocortical adenomas in the morning at 8 a.m. after a low-dose of dexamethasone and after stimulation with synthetic depot ACTH. Basal and post-dexamethasone hormone levels were also measured in plasma and salivary samples of 4 patients with Cushing's syndrome from adrenal adenomas. In the baseline state, patients with non-hyperfunctioning adrenocortical adenomas had significantly higher plasma and salivary 6beta-hydroxycortisol levels (mean+/-SE, 79.0+/-7 and 17.1+/-2.2 ng/dl, respectively) compared to those measured in controls (62.0+/-4 and 7.7+/-0.6 ng/dl, respectively), whereas baseline plasma and salivary cortisol levels (9.6+/-0.5 microg/dl and 342+/-39 ng/dl, respectively) were similar to those measured in the control group (9.9+/-0.4 microg/dl and 366+/-24 ng/dl, respectively). In all groups, the changes in plasma and salivary 6beta-hydroxycortisol concentrations after dexamethasone suppression and ACTH stimulation were similar to the changes in plasma and salivary cortisol levels, although the differing ratios of 6betaOHF to cortisol indicated potentially important variations in the induction of 6beta-hydroxylase activity between the three groups. In patients with Cushing's syndrome, baseline plasma and salivary 6beta-hydroxycortisol concentrations (754+/-444 and 104+/-88 ng/dl, respectively) were more markedly increased than plasma and salivary cortisol levels (24.8+/-6.7 microg/dl and 1100+/-184 ng/dl, respectively), and all remained non-suppressible after dexamethasone administration. These results suggests that plasma and salivary 6beta-hydroxycortisol determinations may precisely detect not only overt increases of cortisol secretion in patients with Cushing's syndrome but also mild glucocorticoid overproduction presumably present in patients with non-hyperfunctioning adrenocortical tumors.     

Plasma cortisol and corticosterone concentrations in the golden hamster, (Mesocricetus auratus)

Because some recent studies of hamster adrenocortical function have depended on older studies that may have been inadequate or misinterpreted, the present study re-examined plasma corticosterone and cortisol concentrations in hamsters under several conditions to determine which plasma glucocorticoid predominated in this animal. Sensitive radioimmunoassays were used to measure separately the two glucocorticoids in the basal condition, after adrenocorticotropin (ACTH) treatment, after acute stress, and after chronic stress. In the basal condition, corticosterone concentrations were 3-4 times higher than those of cortisol. After stimulation, this difference disappeared, but rarely were any hamster's cortisol levels higher than their corticosterone levels. Both ACTH and acute stress elevated plasma corticosterone and cortisol concentrations, but only plasma cortisol concentrations were elevated following chronic stress. The dissociation between cortisol and corticosterone concentrations after chronic stress suggests that the two glucocorticoid hormones in the hamster may be regulated independently. The data also indicate that both corticosterone and cortisol should be measured when assessing adrenocortical function in the hamster.     

Therapy of Cushing''s syndrome with steroid biosynthesis inhibitors

Several substances with different inhibitory effects on adrenal steroid biosynthesis were investigated in patients with Cushing's syndrome. It has been shown that trilostane, a 3β-hydroxysteroid-dehydrogenase inhibitor, is not potent enough to block cortisol biosynthesis in patients with hypercortisolism. Aminoglutethimide inhibits side chain cleavage of cortisol synthesis, but it has been demonstrated that the blocking effect on cortisol secretion is not strong enough to normalize urinary cortisol excretion in patients with Cushing's disease. For metyrapone, an inhibitor of adrenal 11β-hydroxylase, promising results were reported for the treatment of Cushing's syndrome. However, the drug has several side effects and depending on the definition of the desired reduction of cortisol secretion a true remission was only found in a minority of patients. The antifungal drug ketoconazole in vitro predominantly blocks 17,20-desmolase (IC₅₀ 1 μM) and to a lesser extent 17-hydroxylase (IC₅₀ 10 μM) and 11β-hydroxylase (IC₅₀ 15–40 μM). Therefore, ketoconazole in vivo most potently suppresses androgen secretion and only to a lesser extent cortisol biosynthesis. Several therapeutic trials with ketoconazole treatment in patients with pituitary Cushing's disease showed various remission rates between 30 and 90%. In contrast, in almost all patients with benign, primary adrenal Cushing's syndrome cortisol levels were normalized. In patients with ectopic ACTH syndrome ketoconazole was effective in about 50% of all reported cases, while cortisol hypersecretion due to adrenocortical carcinoma was only rarely inhibited by ketoconazole. The main side effect of ketoconazole treatment was liver toxicity which occurred in 12% of all treated patients. In contrast to ketoconazole, the narcotic drug etomidate shows a strong inhibitory effect on 11β-hydroxylase (IC₅₀ 0.03–0.15 μM) but only a weak inhibition of 17,20 desmolase (IC₅₀ 380 μM). This correlates with in vivo studies where even low, non-hypnotic doses of etomidate induced a pronounced fall in serum cortisol levels in normals and in patients with Cushing's syndrome. However, its clinical use is limited by its mandatory intravenous application and its sedative effects. In conclusion, ketoconazole remains the only available steroid-inhibitory drug for a therapeutic trial in patients with Cushing's syndrome who cannot be treated definitively by surgery.     

Saliva cortisol levels following dexamethasone administration in endogenously depressed patients

Saliva and serum cortisol levels were measured in 11 patients with primary major depression, endogenous subtype, and in 9 control subjects before and 8, 16, and 24 hours after dexamethasone administration (1.0 mg p.o.). Six of the 20 subjects had post-dexamethasone serum cortisol concentrations greater than 50 ng/ml and thus were considered “escapers” from dexamethasone suppression. These six subjects also had saliva cortisol concentrations which were significantly elevated compared to those of the suppressors. Measurement of saliva cortisol holds promise as a non-invasive technique for assessing CNS-pituitary-adrenal function in endogenously depressed patients.     

Secretion of 6beta-hydroxycortisol by normal human adrenals and adrenocortical adenomas

Although 6beta-hydroxycortisol (6betaOHF) is usually considered a cortisol metabolite produced by the liver, a few reports suggest that it may also originate from extrahepatic sources. To examine whether human adrenal cells are capable of 6beta-hydroxylating cortisol, we measured 6betaOHF secretion with a radioimmunoassay method in isolated human adrenal cell systems obtained from three normal adrenals, four nonhyperfunctioning adrenocortical adenomas, two adrenal adenomas causing Cushing's syndrome, and five aldosterone (Aldo)-producing adenomas. Cells were examined both under basal conditions and after stimulation with adrenocorticotrophic hormone (ACTH). In addition, 6betaOHF concentrations were determined in inferior vena cava and suprarenal vein plasma samples obtained from the side of nonhyperfunctioning adrenal adenomas (five patients) and aldosterone-producing adenomas (five patients). Under basal incubation conditions, 6betaOHF secretion, expressed as a percent of cortisol secretion, was between 0.5 and 2.0% in normal adrenal cells, between 1.0 and 7% in cells from nonhyperfunctioning adenomas, 12 and 15% in cells from Cushing's syndrome patients, and between 2.6 and 3.9% in cells from aldosterone-producing adenomas. In these cells, increasing doses of ACTH produced a dose-dependent stimulation of both 6betaOHF and cortisol secretion. The 6betaOHF concentration in suprarenal vein samples obtained from the side of adenomas was markedly increased; the suprarenal vein/inferior vena cava 6betaOHF ratios were 13.1+/-2.1 (mean+/-S.E.) in the case of nonhyperfunctioning adenomas and 17.8+/-4.5 in the case of aldosterone-producing adenomas. These results firmly suggest that 6betaOHF is not only a hepatic metabolite, but also a secretory product of human adrenals and that similarly to cortisol, its secretion may be controlled by ACTH.     

Adrenocortical function in deoxycorticosterone acetate (DOCA)-hypertensive Yucatan miniature swine

Adrenocortical function was assessed in six normal and six chronic (greater than 12 weeks), DOCA-hypertensive Yucatan miniature swine; mean arterial pressures were 115.3 +/- 11.7 and 163.6 +/- 27.2 mm Hg, respectively (mean +/- SEM). Adrenocortical function was evaluated in vivo by measuring changes in plasma cortisol and aldosterone in response to exogenous ACTH (0.25 mg, iv), and in vitro by measuring the responses of collagenase-isolated adrenocortical cells to ACTH and angiotensin II. Corticoids were measured by specific radioimmunoassay. Basal plasma cortisol values of conscious DOCA-hypertensive swine were approximately 53% of the values of normotensive swine (P less than 0.05). However, ACTH induced a 419% increase in plasma cortisol values in DOCA-hypertensive swine compared to a 261% increase in the normotensive swine (P less than 0.05). These differences between the two groups were not altered by anesthesia. There were no significant differences in ACTH-induced changes in plasma aldosterone between the normotensive and DOCA-hypertensive swine. Experiments in vitro showed that the corticoid secretory responses of adrenocortical cells from DOCA-hypertensive animals were 6 times more sensitive to ACTH and 3.2 times more sensitive to angiotensin II than those of cells from normotensive swine. Thus, despite the possibility of adrenocortical insufficiency due to suppressed plasma renin activity and the negative feedback of DOCA on the hypothalamic-hypophyseal-adrenal axis, adrenocortical function of DOCA-hypertensive swine was hyperresponsive to trophic hormones. Results from this study suggest that the DOCA-hypertensive swine may be a valuable model in elucidating the relationship between hypertension and adrenocortical function and in investigating nonclassical control of the adrenal cortex, that is, control exerted during the hypertensive state that exists apart from or in addition to that exerted by ACTH and angiotensin II.     

Adrenocortical function in type II hyperlipoproteinemic patients treated with lovastatin (mevinolin)

Lovastatin (Mevinolin), a competitive inhibitor of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase, has been used effectively as a hypocholesterolemic agent in man. As an inhibitor of endogenous cholesterol synthesis, a potentially serious side effect of therapy with this drug is interference with adrenocortical function. The effect of lovastatin on adrenal function was evaluated in a 6-month, randomized, double blinded, placebo-controlled, crossover study involving 24 type II hyperlipoproteinemic patients. Despite significant lowering of total and low density lipoprotein (LDL) cholesterol by lovastatin, no statistically or clinically significant differences were seen in free cortisol excretion or in plasma cortisol response to intravenous ACTH infusion between baseline, placebo, and lovastatin-treated patients. We conclude that lovastatin does not adversely affect adrenocortical reserve in patients with heterozygous familial hypercholesterolemia (FH) or non-FH type II hyperlipoproteinemia.     

ADRENAL FUNCTION IN WILD AND REHABILITATED PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) AND IN SEALS WITH PHOCINE HERPESVIRUS-ASSOCIATED ADRENAL NECROSIS

Adrenal function in harbor seals (Phoca vitulina richardii) was evaluated using adrenocorticotrophic hormone (ACTH) stimulation tests and fecal cortisol levels. The effect of ACTH administration on plasma cortisol and aldosterone levels in five free-living and 14 rehabilitated harbor seal pups was determined using enzyme immunoassay and radioimmunoassay, respectively. In free-living seals, injection of ACTH caused a significant increase in mean plasma cortisol but not of mean aldosterone levels 60 min postinjection. In these seals, mean initial plasma aldosterone was significantly higher than initial levels in rehabilitated seals, while initial cortisol levels were similar. Of the rehabilitated seals, eight died with adrenal cortical necrosis associated with herpesvirus inclusions, while six lived to be released. In the seals that were released, both mean initial cortisol levels and response to ACTH decreased through rehabilitation. In the seals that died, mean initial cortisol and response to ACTH increased through rehabilitation. The differences between initial cortisol levels in seals that lived and those that died were significant at weeks two and four of rehabilitation but not at the week of admission. There was considerable individual variation in initial plasma aldosterone levels and responses to ACTH, although initial aldosterone levels were significantly higher in rehabilitated seals that died than in seals that lived. Seals with adrenal necrosis associated with herpesvirus infection did not have decreased adrenal hormone responses to ACTH. Differences between initial hormone levels and responses to ACTH in different groups of seals may be associated with differing stress levels. Fecal cortisol assays were not a useful method of assessing adrenal function in these seals, as measured levels did not correlate with plasma cortisol levels.     

Serious renal transplant rejection and adrenal hypofunction after gradual withdrawal of prednisolone two years after transplantation.

Ten patients with stable renal function two years after transplantation had their sole immunosuppressive treatment (oral prednisolone 10 mg daily) withdrawn by reducing the daily dose by 1 mg at monthly intervals. Plasma prednisolone concentration, cortisol concentration, creatinine clearance, and serum creatinine concentration were measured in all patients, and the adrenal response to corticotrophin was determined in five by measuring plasma cortisol concentrations before and after tetracosactrin injection. No episodes of rejection occurred in patients taking over 7 mg prednisolone daily. Although three patients apparently required only minimal immunosuppressive treatment (less than 5 mg daily) the remainder suffered episodes of rejection at daily doses below 7 mg. There was a tenuous association between rejection and low plasma cortisol concentration, but neither the pattern of plasma prednisolone concentrations nor the response to tetracosactrin were related to episodes of rejection. Reducing the daily dose of oral prednisolone to under 7 mg should not be attempted in patients with renal transplants unless there are extenuating circumstances.     

Hyper-responsiveness of adrenal gland to vasopressin resulting in enhanced plasma cortisol in patients with adrenal nodule(s)

Hyper-responsiveness of plasma cortisol to vasopressin has been demonstrated in ACTH-independent bilateral macronodular adrenocortical hyperplasia (AIMAH) and some adrenal adenomas with Cushing's syndrome (CS). However, the clinical significance of hyper-responsiveness of plasma cortisol to vasopressin has not been investigated systematically in adrenal nodule(s). The aim of this study was to clarify the prevalence of hyper-responsiveness of plasma cortisol to vasopressin (vasopressin responder) and their clinical characteristics in terms of hormonal secretion using vasopressin-loading test in the patients with adrenal nodule(s) except pheochromocytomas. A vasopressin-loading test was performed on 61 consecutive patients with adrenal nodules (CS: 33, aldosterone-producing adenoma: 10, non-functional tumor: 18). Vasopressin responders were observed in 36.1% of adrenal nodule(s), 42.4% of CS and 28.5% of non-CS. In responders with CS, eight patients had bilateral nodules that were diagnosed as AIMAH, and the remaining six patients had a unilateral nodule. These patients had lower plasma cortisol than non-responders at both morning (P<0.01) and midnight (P<0.05), as well as the morning following overnight dexamethasone suppression at 1mg (P<0.05) and 8mg (P<0.05). Hyper-responsiveness of the adrenal gland to vasopressin resulting in enhanced plasma cortisol was frequently observed among patients with adrenal nodule(s). The vasopressin responders among the patients with adrenal nodule(s) frequently had CS with low autonomous cortisol secretion.     

Nuclear diameter as a criterion of adrenocortical activity in a teleost fish Coregonus lavaretus (L.)

A direct comparison of plasma cortisol levels and mean nuclear diameter of adrenocortical cells in the same fish was carried out, to determine whether nuclear diameter could be used as a valid criterion of adrenocortical activity in Coregonus lavaretus (L.). Specimens were caught and killed by a variety of methods and at different seasons, providing a range of plasma cortisol concentrations, which were measured by gas-liquid chromatography. The head-kidneys of the same fish were immediately fixed and the diameters of 20 adrenocortical cell nuclei measured in 7 μm sections of each, prepared by strictly standardized methods. The correlation coefficient was 0·54, so that nuclear diameter cannot be regarded as an accurate criterion of adrenocortical activity.     

缺锌对大鼠血液皮质醇和ACTH含量及大脑皮质NO合酶活性的影响

就缺锌对大鼠血液皮质醇和促肾上腺皮质激素（ACTH）含量以及大脑皮质NO合酶活性的影响进行了研究,生长大鼠随机分为3组,即缺锌组,对喂组和缺锌补锌组（先饲喂缺锌饲料21天后再补锌）,饲养实验的持续时间为35d。与对喂组比较,缺锌组大鼠血液中皮质醇含量显著升高,而血液ACTH浓度以及大脑皮质NO合酶活性明显降低,此结果提示锌可影响下丘脑－垂体一肾上腺皮质轴和NO合酶的代谢。     

Plasma immunoassayable ACTH levels during and after hydrocortisone infusion in patients with Cushing's disease.

The plasma ACTH responses to hydrocortisone infusion were compared in patients with Cushing's disease and primary adrenocortical insufficiency. In 4 patients with primary adrenocortical insufficiency, plasma ACTH levels were suppressed exponentially after administration of a relatively large dose of hydrocortisone (1.0 mg/kg/1.5 hr-3.0 mg/kg/2 hr). In patients with post-adrenalectomized Cushing's disease (4, bilateral; 1, unilateral), plasma ACTH suppression was delayed. Plasma ACTH levels, expressed as a percentage of the basal concentrations, were significantly less suppressed in patients with Cushing's disease than in patients with primary adrenocortical insufficiency 90 (p less than 0.05) and 120 (p less than 0.05) min after the beginning of infusion. When 0.5 mg/kg hydrocortisone was infused over a period of 1.5 hr, suppression was also delayed in Cushing's disease, and plasma ACTH levels were less suppressed in 4 patients with Cushing's disease than in 4 patients with primary adrenocortical insufficiency at 30 (p greater than 0.05), 45 (p greater than 0.05) 60 (p less than 0.05) min.     

Renal function after long-term treatment with lithium.

Daily urine volumes, plasma creatinine concentrations, and creatinine clearance were measured in 106 patients with unipolar and bipolar affective disorders attending a "lithium" clinic. Urine volumes exceeded 3.51 in only six patients, plasma creatinine concentrations exceeded 150 mumol/1 (1.7 mg/100 ml) in only five, and creatinine clearance was below 50 ml/min in 16. Renal function was assessed by measuring creatinine clearance and renal tubular function, including response to 20 hours of water deprivation, in a representative sample of 30 patients from the lithium clinic and 30 psychiatric patients matched for age and sex who were taking other psychotropic drugs. Creatinine clearance and tubular function, including urine osmolality after water deprivation, were not significantly different between the two groups. Urinary excretion of arginine vasopressin (AVP), however, was much greater in the lithium-treated patients, who therefore had a diminished tubular responsiveness to AVP. The findings do not support suggestions that long-term lithium treatment results in seriously impaired renal function, renal damage, and polyuria. Compared with other series, however, the patients were being maintained with low serum lithium concentrations, which apparently area as effective prophylactically as higher concentrations.     

Flunisolide nasal spray for perennial rhinitis in children.

Twenty-seven children with perennial rhinitis entered a double-blind cross-over study comparing nasal sprays of flunisolide---a new topical corticosteroid---and placebo. Symptoms were assessed over two consecutive monthly periods with each treatment. Weekly diary cards, monthly clinical assessments, and end-of-trial preferences all favoured the active drug. At the end of the trial 20 patients preferred the treatment month with flunisolide, four preferred the placebo month, and two rated the periods equally. Side effects were mild, the commonest being transient nasal stinging. Seventeen children who derived benefit from flunisolide continued with the treatment for a six-month open-study period. Many reduced the dosage from three times to twice or once daily without losing benefit. The effect of flunisolide on the pituitary-adrenal axis was assessed in seven children by measuring the 0900 blood cortisol concentrations at two-month intervals over the six months. No effect was observed. The results show that flunisolide is effective and safe for the treatment and prophylaxis of perennial rhinitis in children.     

Physiological responses to exercise and hypoglycaemia stress in pigs of differing adrenal responsiveness

• 1.1. Twelve Large White × Landrace male pigs, six with high adrenocortical response to ACTH, and six with low response, were subjected to mild and moderate exercise, and then to insulin-induced hypoglycaemia.
• 2.2. Plasma ACTH, cortisol, catecholamines and some haematological and plasma biochemical parameters were determined in response to exercise, and glucose and cortisol in response to insulin challenge.
• 3.3. High responders had significantly greater increases than low responders in ACTH, cortisol and catecholamines following exercise, and in cortisol following insulin challenge.
• 4.4. The results suggest that differences in adrenocortical response to exogenous ACTH are an accurate reflection of the animal's response to stressful stimuli.

     

Plasma triiodothyronines in fetal sheep: effects of illness and thyroidectomy.

Plasma 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine concentrations were measured in fetal sheep prior to death in utero and after thyroidectomy. In six fetal sheep who subsequently died in utero, plasma rT3 concentrations were elevated in all for 2 to 13 days prior to death. There were no consistent changes in plasma T4 concentrations. In two thyroidectomized fetal sheep, plasma T4 and rT3 concentrations fell to low levels. Plasma T3 concentrations remained low and there was no increase in plasma T3 in the last week prior to parturition like that which occurs in normal fetal sheep. Parturition was preceded by the normal increase in fetal plasma cortisol concentrations and occurred at the normal time. These data indicate that plasma rT3 concentrations are increased as a result of illness in fetal sheep and that such measurements may be useful as an indicator of fetal distress. The normal increase in plasma T3 late in gestation is not necessary for the late gestational cortisol surge or for normal parturition.     

Glucocorticoid- and Androgen-Secreting Black Adrenocortical Adenomas: Unique Cause of Corticotropin-Independent Cushing Syndrome

ObjectiveTo describe the unique association of corticotropin-independent Cushing syndrome caused by cortisoland androgen-secreting black adrenal cortical adenomas with myelolipomatous change.MethodsWe report the clinical, laboratory, radiologic, and pathologic findings from 2 patients who presented with androgen excess and typical signs and symptoms of Cushing syndrome.ResultsEndocrine investigations showed high serum cortisol concentrations that lacked diurnal rhythm, undetectable plasma corticotropin concentrations, and absence of serum cortisol suppression after overnight dexamethasone suppression tests. Serum levels of adrenal androgens were elevated. Computed tomography of the abdomen revealed unilateral adrenal masses (largest lesional diameters 4.0 and 3.1 cm). On the basis of the plurihormonal hypersecretion and the imaging characteristics, adrenocortical carcinoma was considered as a possible diagnosis. However, histopathologic analysis in both patients revealed black adrenal cortical adenomas with myelolipomatous change. After surgery, adrenal androgens normalized, and the signs and symptoms of Cushing syndrome and androgen excess resolved. There was no evidence of recurrent disease at last follow-up.ConclusionsA unique form of corticotropin-independent Cushing syndrome is described: cortisoland androgen-secreting black adrenal cortical adenomas with myelolipomatous change. Although most patients with corticotropin-independent Cushing syndrome associated with androgen excess prove to have adrenocortical carcinoma, the clinician should be aware of the possibility of benign, black adrenal adenomas in this clinical setting. (Endocr Pract. 2011;17:e73-e78)     

Adrenocortical suppression in workers manufacturing synthetic glucocorticoids.

A man who had worked for 16 years in the manufacture of a potent corticosteroid was found to be suffering from chronic adrenocortical insufficiency attributed to chronic absorption of the glucocorticoid. Eleven other symptom-free workers were therefore screened. Two of these workers, like the first patient, gave grossly abnormal responses to the Synacthen (tetracosactrin) test; one had been employed for only seven months. All 12 men had facial plethora, suggesting absorption of the drug in spite of their having adhered to the safety precautions. All workers manufacturing potent steroids should therfore be screened regularly by measurement of their plasma cortisol concentrations and should be moved regularly to processing other drugs.     

Effects of adrenocorticotropin stimulation on cortisol dynamics of pregnant gilts and their fetuses: implications for prenatal stress studies

The effect of adrenocorticotropic hormone (ACTH) administration on plasma cortisol concentrations was determined in pregnant gilts and their fetuses. In a first experiment, 100 IU ACTH (Synacthen Depot) was administered intramuscularly to the gilts every second day from Days 49 to 75 of gestation. ACTH injections were carried out at 08:00 h and, thereafter, 10 blood samples were taken within the following 8h via jugular catheters. Blood samples were analysed for plasma cortisol concentrations, and results were compared with values from animals which were treated with physiological saline and untreated animals (blood sampling only). The values for plasma cortisol concentrations increased until 3h after ACTH applications to a mean maximum level of 276.5+/-17.2 nmol/l in the whole 4-week stimulation period. Plasma cortisol levels did not return to pre-treatment values within the 8 h post-injection. No differences in cortisol levels were found between the physiological saline and untreated control, and no habituation of the adrenocortical response to ACTH was found during the 4-week stimulation period. In a second experiment, 100 IU ACTH were administered to pregnant gilts at gestation Day 65. After 3 h, fetuses were recovered under general anaesthesia and blood samples were taken from the umbilical vein, artery, and, after decapitation, from periphery. Application of ACTH to the sows significantly increased their plasma cortisol concentrations (P<0.001), and also increased plasma cortisol concentrations in peripheral blood samples from the fetuses (P=0.09) and in the umbilical vein (P<0.001) and artery (P<0.01), respectively. Plasma ACTH concentrations did not differ in fetuses from ACTH-treated or control sows. The results show that in gilts the adrenocortical response to an exogenous application of Synacthen Depot is consistent over time during mid-gestation. Furthermore, cortisol but not ACTH levels were increased in fetuses from ACTH-treated sows, indicating that maternal cortisol can cross the placenta during mid-gestation. The stimulation of maternal cortisol release through exogenous ACTH with subsequent elevation of fetal cortisol levels is, therefore, a useful approach for studying effects of elevated maternal glucocorticoids in prenatal stress studies in pigs.