ACTH-stimulated Cortisol Research Articles

Cryptochrome 2 Expression Level Is Critical for Adrenocorticotropin Stimulation of Cortisol Production in the Capuchin Monkey Adrenal

Timely production of glucocorticoid hormones in response to ACTH is essential for survival by coordinating energy intake and expenditure and acting as homeostatic regulators against stress. Adrenal cortisol response to ACTH is clock time dependent, suggesting that an intrinsic circadian oscillator in the adrenal cortex contributes to modulate the response to ACTH. Circadian clock gene expression has been reported in the adrenal cortex of several species. However, there are no reports accounting for potential involvement of adrenal clock proteins on cortisol response to ACTH. Here we explored whether the clock protein cryptochrome 2 (CRY2) knockdown modifies the adrenal response to ACTH in a primate. Adrenal gland explants from adult capuchin monkey (n = 5) were preincubated for 6 h with transfection vehicle (control) or with two different Cry2 antisense and sense probes followed by 48 h incubation in medium alone (no ACTH) or with 100 nm ACTH. Under control and sense conditions, ACTH increased cortisol production, whereas CRY2 suppression inhibited ACTH-stimulated cortisol production. Expression of the steroidogenic enzymes steroidogenic acute regulatory protein and 3beta-hydroxysteroid dehydrogenase at 48 h of incubation was increased by ACTH in control explants and suppressed by Cry2 knockdown. Additionally, we found that Cry2 knockdown decreased the expression of the clock gene brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein (Bmal1) at the mRNA and protein levels. Altogether these results strongly support that the clock protein CRY2 is involved in the mechanism by which ACTH increases the expression of steroidogenic acute regulatory protein and 3beta-hydroxysteroid dehydrogenase. Thus, adequate expression levels of components of the adrenal circadian clock are required for an appropriate cortisol response to ACTH.

ACTH and cortisol response to critical illness in term and late preterm newborns

ObjectiveTo determine cortisol and adrenocorticotropin (ACTH) responses to critical illness in term and late preterm newborns and examine the relationship of these values to measures of clinical illness, including markers of cardiovascular dysfunction.Study DesignIn this prospective observational study, we measured ACTH, baseline cortisol, and ACTH-stimulated cortisol concentrations in mechanically ventilated infants ≥ 34 weeks gestational age and <5 postnatal days. ACTH-stimulated cortisol concentrations were also measured in a comparison group of non-critically ill, non mechanically-ventilated infants. The relationship of these values to measures of severity of illness including SNAP (score for neonatal acute physiology) scores, blood pressure and vasopressor initiation was examined.ResultConcentrations are presented as median [25th -75th percentile]. Baseline cortisol values in critically ill infants (n=35) were 4.6 mcg/dl [3.0-16.2]; 26 (74%) of these were <15 mcg/dl. ACTH-stimulated cortisol values were not significantly different from the comparison group (41 mcg/dl [30.3-51.8] vs.34.2 mcg/dl [25.2-43.3]). ACTH concentrations in ill infants (n=10) were 12 pg/ml [5.5-19.2]. Neither baseline cortisol, stimulated cortisol nor ACTH increased significantly with increasing severity of illness. 71% of the ill infants received vasopressor therapy for hypotension. Cortisol concentrations in these infants were similar to those infants who did not receive vasopressor therapy.ConclusionThe majority of these critically ill newborns had very low cortisol and ACTH values without the expected increase in response to critical illness; however, their response to exogenous ACTH was normal. These results demonstrate that the inadequate response to critical illness in these newborns does not result from adrenal dysfunction. We therefore hypothesize that this is a secondary insufficiency arising from inadequate stimulation of the adrenal gland.

La melatonina reduce la respuesta de cortisol al ACTH en humanos

Melatonin receptors are widely distributed in human tissues but they have not been reported in human adrenal gland. To assess if the human adrenal gland expresses melatonin receptors and if melatonin affects cortisol response to ACTH in dexamethasone suppressed volunteers. Adrenal glands were obtained from 4 patients undergoing unilateral nephrectomy-adrenalectomy for renal cancer. Expression of mRNA MT1 and MT2 melatonin receptors was measured by Reverse TranscriPtase Polymerase Chain Reaction (RT-PCR). The effect of melatonin on the response to intravenous (i.v.) ACTH was tested (randomized cross-over, double-blind, placebo-controlled trial) in eight young healthy males pretreated with dexamethasone (1 mg) at 23:00 h. On the next day, at 08:00 h, an i.v. line was inserted, at 08:30 h, and after a blood sample, subjects ingested 6 mg melatonin or placebo. At 09:00 h, 1-24 ACTH (Cortrosyn, 1 microg/1.73 m2 body surface area) was injected, drawing samples at 0, 15, 30, 45 and 60 minutes after. Melatonin, cortisol, cortisone, progesterone, aldosterone, DHEA-S, testosterone and prolactin were measured by immunoassay. The four adrenal glands expressed only MT1 receptor mRNA. Melatonin ingestion reduced the cortisol response to ACTH from 14.6 +/- 1.45 microg/dl at 60 min in the placebo group to 10.8 +/- 1.2 microg/dl in the melatonin group (p < 0.01 mixed model test). It did not affect other steroid hormone levels and abolished the morning physiological decline of prolactin. The expression of MT1 melatonin receptor in the human adrenal, and the melatonin reduction of ACTH-stimulated cortisol production suggest a direct melatonin action on the adrenal gland.

Cardiac mass-to-maximum power output: A novel index to assess left ventricular efficiency during exercise stress echocardiography

The capacity of the traditional anxiolytic plant, Souroubea sympetala, and its bioactive principle, betulinic acid (BA), to lower cortisol levels in rainbow trout, Oncorhynchus mykiss, was investigated. Effects at the level of the cortisol-producing interrenal cells were investigated using an in vitro head kidney preparation. Head kidney tissue incubated with S. sympetala extract or BA produced significantly less cortisol in response to adrenocorticotropic hormone (ACTH) than cells incubated with ACTH alone; a 50% reduction in the cortisol response was predicted to occur at 43 μg mL− 1 extract or 71 μg mL− 1 BA. To investigate whether effects on interrenal cell cortisol production translated into effects at the whole-animal level, the plasma cortisol response to an acute stressor, confinement in a net, was assessed. Fish fed a commercial trout pellet diet supplemented with 1 mg kg− 1 fish BA for six days exhibited a significantly lower plasma cortisol response to the acute stressor than fish fed the unsupplemented diet. Collectively, these results demonstrate that S. sympetala and BA act on the interrenal cells of the hypothalamic-pituitary-interrenal (HPI) axis in rainbow trout to significantly attenuate the cortisol response to an acute stressor. These findings suggest that BA is of potential use in mitigating effects of exposure to the stressors commonly encountered in an aquaculture setting.•Souroubea sympetala extract and betulinic acid reduced ACTH-stimulated cortisol production by head kidney tissue in vitro, with little or no evidence of cytotoxicity.•The cortisol response to an acute stressor was attenuated in rainbow trout fed a commercial diet supplemented with betulinic acid.•The cortisol-reducing properties of the S. sympetala extract and betulinic acid may be useful in mitigating effects of stress in aquaculture, particularly since, as natural products, they may raise less public concern with respect to human consumption.

Leukemia inhibitory factor protein and receptors are expressed in the bovine adrenal cortex and increase cortisol and decrease adrenal androgen release

The release of adrenal steroids during acute stress is primarily regulated by adrenocorticotropic hormone (ACTH). In contrast, during chronic inflammatory stress additional factors are involved in regulating adrenal function. Leukemia inhibitory factor (LIF) is a pleiotropic cytokine that increases ACTH release from the pituitary. In addition, LIF and LIF receptors (LIFR) are expressed in the human adrenal cortex and the human adrenocortical tumor cell line H295R. Furthermore, LIF increases basal and ACTH-stimulated cortisol release from H295R cells. However, the expression of LIF and LIFR in non-human adrenal glands and the effects of LIF on the release of cortisol from adrenal cells of non-human species have not been determined. Furthermore, the effects of LIF on adrenal androgen release from all species are unknown. In this study, immunohistochemistry, Western blots, RT-PCR, and nucleotide sequencing was utilized to demonstrate that LIF and its receptor are expressed throughout the bovine adrenal cortex. Although LIF did not modify basal cortisol release from dispersed cells isolated from the bovine adrenal zona fasciculate, this cytokine increased ACTH-stimulated release of cortisol from these cells in a manner dependent on the LIF concentration and exposure interval. In contrast, LIF in a concentration-dependent and time-dependent manner decreased basal and ACTH-stimulated adrenal androgen release from dispersed cells isolated from the bovine adrenal zona reticularis. Because LIF release increases during inflammatory stress and this cytokine stimulates adrenal cortisol release and inhibits adrenal androgen release, this cytokine may play an important role in regulating the release of adrenal steroids during inflammatory stress.

Adrenal response to the low dose ACTH stimulation test and the cortisol-to-adrenocorticotrophic hormone ratio in canine babesiosis

This prospective, interventional, case-controlled study sought to determine the association between adrenocortical function and mortality in dogs with naturally occurring Babesia rossi babesiosis. Sixty-eight dogs with canine babesiosis were studied and fifteen normal dogs were used as controls. Blood samples were obtained from the jugular vein in each dog prior to treatment, at admission to hospital, for the measurement of basal plasma ACTH (adrenocorticotrophic hormone) and serum cortisol concentrations. Immediately thereafter, each dog was injected intravenously with 5 μg/kg of ACTH (tetracosactrin). A second blood sample was taken 1 h later for serum ACTH-stimulated cortisol measurement and the resultant calculation of delta cortisol by subtracting basal from ACTH-stimulated cortisol. Diagnosis of babesiosis was confirmed by polymerase chain reaction (PCR) and reverse line blot (RLB). Three outcomes were defined: hospitalization with subsequent death ( n = 4); hospitalization followed by recovery ( n = 48); and treatment as an outpatient ( n = 16). Basal cortisol, but not ACTH-stimulated cortisol, was significantly higher in patients compared to control dogs. Basal- and ACTH-stimulated serum cortisol concentrations were significantly higher in the dogs that died, compared to hospitalized dogs that survived and compared to dogs treated as outpatients. There was no significant difference in delta cortisol concentrations or cortisol to ACTH ratios across outcome groups in dogs suffering from B. rossi babesiosis However, dogs with delta cortisol concentrations below 83 nmol/l had significantly higher cortisol to ACTH ratios compared to dogs with delta cortisol concentrations above 83 nmol/l. These findings of increased basal- and ACTH-stimulated cortisol and increased cortisol to ACTH ratios confirm the absence of adrenal insufficiency and concur with those in human malaria.

Interleukin-4 increases cortisol release and decreases adrenal androgen release from bovine adrenal cells

ACTH is the primary regulator of adrenal function during acute stress. However, during chronic inflammatory stress additional factors play a major role in the regulation of adrenal secretion. Many cytokines circulate in the blood and are synthesized and released from adrenal tissue. Furthermore, these peptides modify adrenal function. Recently, interleukin-4 (IL-4) was demonstrated to be released from a human adrenal tumor cell line. Therefore, we hypothesized that normal bovine adrenocortical cells could express IL-4 and that this cytokine may modify adrenal function. We determined that IL-4 and IL-4 receptors (IL-4R) are expressed in the bovine adrenal cortex whereas the expression of IL-4 and IL-4R in the adrenal medulla was not apparent. Exposure of dispersed bovine adrenocortical cells isolated from the zona fasciculate to IL-4 did not modify basal release of cortisol. However, the ACTH-stimulated release of cortisol from the bovine adrenal cells was augmented by IL-4. IL-4 exposure had no affect on adrenal androgen release from bovine zona reticularis cells, but IL-4 inhibited the ACTH-stimulated release of adrenal androgens from these cells. The effects of IL-4 on ACTH-stimulated cortisol and adrenal androgen release were dependent upon the IL-4 incubation interval and the IL-4 concentration. Because communication between the immune and endocrine systems is important in inflammatory conditions, IL-4 may play a role in coordinating the adrenal response to inflammatory stress.

Comparison of the hypothalamic–pituitary–adrenal axis susceptibility upon single-dose i.m. depot versus long-acting i.v. triamcinolone acetonide therapy: a direct pharmacokinetic correlation

The effects of single injections of glucocorticoid (GC) depot suspension and of long-acting GC were studied in conscious dogs. Both the depot suspension GC triamcinolone-16,17-alpha-acetonide (TAA) and the long-acting triamcinolone acetonide-21-dihydrogen phosphate (TAA-DHP) decreased basal and ACTH-stimulated cortisol levels and in a specific time-dependent way. Before treatment, all dogs had normal basal and peak cortisol responses to ACTH challenge (13-15 and > 120 nmol/l at 1 h respectively). Intravenous TAA-DHP reduced cortisol levels for 12 h, i.m. TAA reduced cortisol levels as of 1.5 h and the effect lasted for at least 4 weeks. Both treatments blunted the peak response to ACTH. ACTH elevated cortisol levels to or above baseline values within 10 days following TAA-DHP treatment, but the TAA treatment suppressed an ACTH response for at least 4 weeks. Kinetic analysis of both the preparations demonstrated rapid absorption (tmax, 0.6-1.5 h) and low maximum plasma concentrations (peak Cmax, 2.99-5.51 nmol/l) of the steroids; indeed, the terminal half-life of TAA-DHP (13.9 +/- 1.3 h) was very much shorter than that of TAA (125.9 +/- 15.8 h). In addition, the mean residence time differed very much (11 vs 160 h for TAA-DHP and TAA respectively), in line with a delayed elimination of the depot compared with the long-acting formulation. Application of these TAA formulations needs careful evaluation for their surprisingly different effects on endocrine stress axis activity.

Endocrine Dysfunction in Patients with Fabry Disease

Fabry disease (FD) is a genetic disorder caused by lysosomal alpha-galactosidase-A deficiency and is characterized by the systemic accumulation of globotriaosylceramide. All endocrine glands are susceptible to globotriaosylceramide accumulation because of their high vascularization and low cellular proliferation rate. Nevertheless, this endocrine system has never been investigated in detail. We aimed to investigate the function and morphology of the endocrine glands in FD. The thyroid, gonadal, adrenal, and GH/IGF-I axes were evaluated in 18 FD patients (nine females and nine males, aged 21-64 yr) and 18 sex- and age-matched healthy subjects. We conducted an observational, analytical, open, prospective study. Ten of the 18 patients received enzyme replacement therapy (ERT) with recombinant human alpha-galactosidase-A (agalsidase beta) at a dose of 1 mg/kg body weight every 2 wk. FD patients had higher baseline TSH levels than controls (P < 0.01). Three subjects were diagnosed with an early stage of subclinical primary hypothyroidism associated with negative antithyroid antibodies. A history of menses abnormalities, miscarriage, or assisted delivery was found in 89% of FD women. Asthenozoospermia, oligozoospermia, or both were found in all FD men through seminal fluid analysis. FD patients had significantly higher circulating ACTH and lower cortisol levels than controls (P < 0.05). In patients under ERT, a suboptimal cortisol response to the 250-microg ACTH test was found in 10%, and the ACTH-stimulated cortisol peak was significantly correlated to the health status profile (P < 0.05). A variety of latent endocrine dysfunctions, including life-threatening conditions, occur in patients with FD. Endocrine dysfunctions are also present in patients already receiving ERT and are in part related to their persistent poor quality of life. An endocrine work-up should be recommended in all FD patients. Adequate monitoring and hormonal therapy, when required, have to be performed in cases of subclinical endocrine dysfunction to avoid life-threatening events.

Insulin resistance, endocrine function and adipokines in type 2 diabetes patients at different glycaemic levels: potential impact for glucotoxicity in vivo

To evaluate the interplay between hyperglycaemia, insulin resistance, hormones and adipokines in patients with type 2 diabetes mellitus (T2DM). Ten patients with T2DM with good glycaemic control (G), 10 with poor control (P) and 10 nondiabetic control subjects (C) were matched for sex (M/F 6/4), age and body mass index. A hyperinsulinaemic, euglycaemic clamp was performed and cytokines and endocrine functions, including cortisol axis activity were assessed. Patients with diabetes were more insulin resistant than group C, and group P exhibited the highest degree of insulin resistance (P = 0.01, P vs C). Tumour necrosis factor (TNF)-alpha levels were elevated in patients with diabetes (P = 0.05) and group P had the highest levels of fasting serum cortisol (P = 0.05), nonesterified fatty acids (NEFA; P = 0.06) and C-reactive protein (CRP; P = 0.01). Adiponectin levels were lower in the P group. In partial correlation analyses, significant associations were found: glycaemic level (HbA1c) with insulin resistance, TNF-alpha, CRP and basal and ACTH-stimulated cortisol levels, insulin resistance with plasma NEFA, TNF-alpha and stimulated cortisol levels. Poor glycaemic control in patients with T2DM was associated with insulin resistance and with elevated TNF-alpha, CRP and basal as well as stimulated cortisol levels. Inflammatory mediators, e.g. TNF-alpha, may contribute to insulin resistance in hyperglycaemic patients with T2DM and this might be a partial explanation for glucotoxicity.

The N-Terminal Neurotensin Fragment, NT1–11, Inhibits Cortisol Secretion by Human Adrenocortical Cells

Neurotensin (NT) modulates corticosteroid secretion from the mammalian adrenal gland. The objective of this study was to investigate the possible involvement of NT in the control of cortisol secretion in the human adrenal gland. In vitro studies were conducted on cultured human adrenocortical cells. This study was conducted in a university research laboratory. Adrenal explants from patients undergoing expanded nephrectomy for kidney cancer were studied. Cortisol secretion from cultured adrenocortical cells was measured. NT1-11, the N-terminal fragment of NT, dose-dependently inhibited basal and ACTH-stimulated cortisol production by human adrenocortical cells in primary culture. In contrast, NT had no influence on cortisol output at concentrations up to 10(-6) m. HPLC and RT-PCR analyses failed to detect any significant amounts of NT and NT mRNA, respectively, in adrenal extracts. Molecular and pharmacological studies were performed to determine the type of NT receptor involved in the corticostatic effect of NT1-11. RT-PCR analysis revealed the expression of NT receptor type (NTR) 3 mRNA but not NTR1 and NTR2 mRNAs in the human adrenal tissue. However, the pharmacological profile of the adrenal NT1-11 receptor was different from that of NTR3, indicating that this receptor type is not involved in the action of NT1-11 on corticosteroidogenesis. Our results indicate that NT1-11 may act as an endocrine factor to inhibit cortisol secretion through activation of a receptor distinct from the classical NTR1, NTR2, and NTR3.

The effect of therapeutic glucocorticoids on the adrenal response in a randomized controlled trial in patients with rheumatoid arthritis

To measure the effect of low-dose systemic glucocorticoid treatment on the adrenal response to adrenocorticotropic hormone (ACTH) in patients with rheumatoid arthritis (RA). Patients with RA who took part in a randomized double-blind placebo-controlled trial of budesonide (3 mg/day and 9 mg/day) and prednisolone (7.5 mg/day) underwent a short (60-minute) test with injection of ACTH (tetracosactide hexaacetate) at baseline and the day after completing the 3-month treatment program. Plasma cortisol measurements at baseline and 3 months were compared within and between the treatment groups. Individual patients were classified as normal responders to ACTH or as abnormal responders if changes were >2 SD below the pretreatment value in the entire group of study patients. Short tests with ACTH injection were performed on 139 patients before beginning the study medication and on 134 patients after cessation of the medication. There were no changes in the placebo group. Mean plasma cortisol levels following treatment were reduced in all active treatment groups. In addition, mean values were significantly reduced for the 30-minute and 60-minute responses to ACTH. The maximum reduction (35%) occurred in the prednisolone group at 60 minutes. Following treatment, 34% of patients taking budesonide 9 mg and 46% of those taking prednisolone 7.5 mg failed to reach the normal maximum cortisol response to ACTH. Four patients failed to achieve the normal percentage increase in cortisol levels, but only 1 patient failed to meet both criteria. Low doses of a glucocorticoid resulted in depression of baseline and ACTH-stimulated cortisol levels after 12 weeks of therapy. Although the responsiveness of the hypothalamic-pituitary-adrenal axis in individual patients generally remained within the normal range, these changes should be investigated further.

Hypoestrogenism does not mediate social suppression of cortisol in subordinate female marmosets

Behaviorally subordinate female marmosets undergo social suppression of ovulation and hypoestrogenism, as well as chronic reductions in circulating basal cortisol concentrations. Because estrogen elevates hypothalamic-pituitary-adrenal axis activity and circulating glucocorticoid levels in other species, we tested the hypothesis that socially induced hypoestrogenism contributes to cortisol reductions in subordinate female marmosets. We characterized morning basal plasma cortisol levels, as well as cortisol responses to exogenous adrenocorticotropic hormone (ACTH; 0, 1, or 10 microg/kg), in seven anovulatory subordinate females and six ovariectomized, non-subordinate females under two conditions: during long-term treatment with estradiol (E2) and control. Circulating E2 and cortisol levels were compared to those of six dominant females undergoing ovulatory cycles. Basal cortisol concentrations in the control condition were significantly lower in subordinates than in both dominant and ovariectomized females. E2 treatment elevated circulating E2 levels of subordinate and ovariectomized females into the range seen in dominant females but did not increase either mean basal or ACTH-stimulated cortisol levels. To the contrary, E2 treatment caused a decline in basal cortisol levels over time, especially in ovariectomized animals. These results indicate that treatment with exogenous estrogen does not elevate circulating cortisol levels in previously hypoestrogenemic female marmosets and, correspondingly that socially induced hypoestrogenism does not diminish cortisol levels in subordinate females.

Placental 11β-HSD2 Activity, Early Postnatal Clinical Course, and Adrenal Function in Extremely Low Birth Weight Infants

The placental enzyme 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD2) transforms maternal cortisol to inactive cortisone. Fetal glucocorticoid excess due to reduced 11beta-HSD2 activity could make small preterm infants susceptible to early adrenal insufficiency when the maternal cortisol source is no longer sustained. We assessed whether placental 11beta-HSD2 activity is related to early adrenal insufficiency and postnatal clinical course in extremely low birth weight (<1000 g) infants. Mean gestational age of the 44 infants was 26.6 wk (range, 23.7-32.0), birth weight was 747 g (440-981), and relative birth weight was -1.9 SD (-4.9 to 1.0). We determined placental 11beta-HSD2 activity, baseline, and ACTH-stimulated cortisol and assessed illness severity by the Score of Neonatal Acute Physiology (SNAP). One standard deviation decrease in placental 11beta-HSD2 activity corresponded to a 1.85 (95% CI 0.55 to 3.14; p = 0.006) unit increase in SNAP score and 2.9 mm Hg decrease in minimum mean arterial pressure (95% CI 0.3 to 5.6 mm Hg; p = 0.03). Placental 11beta-HSD2 activity was not associated with cortisol concentrations, although the confidence interval of the ACTH-stimulated cortisol was close to zero: 1 SD increase corresponded to 17% (-18% to 49%) increase in ACTH-stimulated cortisol. Moreover, a 1 SD decrease in enzyme activity was associated with a hazard ratio for postnatal glucocorticoid treatment of 1.63 (95% CI 1.00 to 2.65); p = 0.05. In ELBW infants, lower placental 11beta-HSD2 activity is associated with more severe early postnatal illness and hypotension. Although an association with baseline or ACTH-stimulated cortisol was not seen, possible relationships with other components of the hypothalamic-pituitary-adrenal axis remain to be determined.

Salicylate Disrupts Interrenal Steroidogenesis and Brain Glucocorticoid Receptor Expression in Rainbow Trout

Varying levels of pharmaceuticals, including salicylate, ibuprofen, and acetaminophen, have been reported in the aquatic environment, but few studies have actually addressed the impact of these drugs on aquatic organisms. We tested the hypothesis that these pharmaceuticals are endocrine disruptors in fish by examining their impact on interrenal corticosteroidogenesis in rainbow trout. Indeed, acute adrenocorticotrophic hormone (ACTH)-mediated cortisol production in trout interrenal cells in vitro was significantly depressed (20-40%) by these pharmaceutical drugs. Furthermore, we investigated whether this interrenal dysfunction involved inhibition of the steroidogenic capacity in rainbow trout. To this end, we fed trout salicylate-laced feed (100 mg/kg body weight) for 3 days and assessed the transcript levels of key proteins involved in corticosteroidogenesis, including steroidogenic acute regulatory protein (StAR), peripheral-type benzodiazepine receptor (PBR), cytochrome P450 cholesterol side chain cleavage (P450scc), and 11beta-hydroxylase. Salicylate treatment did not affect the resting plasma cortisol or glucose levels, whereas the acute ACTH-stimulated cortisol production was significantly depressed in the interrenal tissue. This disruption of steroidogenesis by salicylate corresponded to a significant drop in the gene expression of StAR and PBR, but not P450scc or 11beta-hydroxylase, compared to the sham-treated fish. Also, brain glucocorticoid receptor (GR) protein content and not GR mRNA level was significantly reduced by salicylate. Taken together, salicylate is a corticosteroid disruptor in trout and the targets include the key rate-limiting step in interrenal steroidogenesis and brain glucocorticoid signaling.

Adrenocortical and thyroid function, hormone and metabolite profiles and the onset of ovarian cyclicity in dairy cows suffering from various forms of ketosis

The involvement of adrenocortical and thyroid hormones in the pathogenesis of ketosis, as well as the ovarian consequences of this metabolic disorder, were studied in _2 parity cows (n=199) in 3 large scale dairy herds. To compare the plasma/serum concentrations of certain hormones Šcortisol, thyroxin (T4), triiodothyronine (T3), insulin, insulin-like growth factor-1 (IGF-1)¹ and metabolites Šglucose (G), acetoacetic acid (ACAC), βOH-butyrate (BHB), non-esterified fatty acid (NEFA), trigliceride (TG), total cholesterol (TCh)¹, and the activity of aspartate aminotransferase (AST), blood samples were taken 1 to 3 days after calving and again 4 times 7 days apart. The ACTH-challenged cortisol responsiveness and the TRH-induced T4/T3 increase were determined between days 1 to 3 and again between days 28 to 35. The resumption of ovarian cyclicity was followed up by individual progesterone (P4) profiles based on milk samples taken 3 times a week for about 80 to 85 days. BHB level of 1 mmol/L was estimated as a border line between hyper- (>1 mmol/L) and normoketonaemic (<1 mmol/L) conditions. Five different ketone patterns were distinguished: (1) non-ketotic (n=98; normoketonaemia in all samples), (2) early type ketosis (n=45; hyperketonemia was detected only in the first week after calving), (3) late type (lactational) ketosis (n=11; after a normoketonaemic period increasing hyperketonaemia was detected in the 5th, or in the 4th and 5th weeks), (4) temporary ketosis (n=11; hyperketonaemia was detected for 1-2 weeks in the 2nd and 3rd or in the 3rd and 4th weeks); (5) long-lasting ketosis (n=34; hyperketonaemia has been detected since calving for 4 to 5 weeks or until dying / emergency slaughtering). Simultaneously with the hyperketonaemic stage increased NEFA, ACAC, depressed TCh, glucose and decreased insulin, IGF-1, T4 and T3 concentrations were detected in almost all the cases. Obvious metabolic and endocrine alterations were found, however, only in long-lasting ketosis. The TRH-stimulated T4 and T3 responses remained almost unaffected proving intact thyroid function in early and late type as well as in temporary ketosis. Depressed thyroid response and delayed onset of cyclic ovarian function were detected only in cases of long-lasting ketosis. The cows characterized by lower than normal (<mean-SD of non-ketotic cows) ACTH-stimulated cortisol response on days 1-3 after calving showed poorer chance for spontaneous recovery. There was a significant negative correlation between the IGF-1 level in the 1st week after calving and the duration of the postpartum acyclic period. In late type (lactational) ketosis the cessation of ovarian cyclicity was the most characteristic genital malfunction.

Serum 17-α-hydroxyprogesterone and corticosterone concentrations in dogs with nonadrenal neoplasia and dogs with suspected hyperadrenocorticism

To assess serum 17-alpha-hydroxyprogesterone (17OHP) and corticosterone concentrations in dogs with nonadrenal neoplasia and dogs being screened for hyperadrenocorticism. Prospective study. 16 clinically normal dogs, 35 dogs with nonadrenal neoplasia, and 127 dogs with suspected hyperadrenocorticism. ACTH stimulation tests were performed in all dogs. Baseline serum cortisol and corticosterone concentrations were measured in the healthy dogs; baseline serum cortisol concentration and ACTH-stimulated cortisol, corticosterone, and 17OHP concentrations were measured in all dogs. Endogenous plasma ACTH concentration was also measured before administration of ACTH in dogs with neoplasia. In 35 dogs with neoplasia, 31.4% had high serum 17OHP concentration and 22.9% had high serum corticosterone concentration. Of the 127 dogs with suspected hyperadrenocorticism, 59 (46.5%) had high ACTH-stimulated cortisol concentrations; of those, 42 of 59 (71.2%) and 32 of 53 (60.4%) had high serum 17OHP and corticosterone concentrations, respectively. Of dogs with serum cortisol concentration within reference range after ACTH administration, 9 of 68 (13.2%) and 7 of 67 (10.4%) had high serum 17OHP and corticosterone concentrations, respectively. In the dogs with neoplasia and dogs suspected of having hyperadrenocorticism, post-ACTH serum hormone concentrations were significantly correlated. Serum concentrations of 17OHP or corticosterone after administration of ACTH may be high in dogs with nonadrenal neoplasia and no evidence of hyperadrenocorticism. Changes in serum 17OHP or corticosterone concentrations after administration of ACTH are proportionate with changes in cortisol concentration.

Pituitary–adrenal axis function in dogs with neoplasia*

Abstract Adrenocorticotropic hormone (ACTH) stimulation tests were done in healthy and tumour-bearing dogs. In the tumour-bearing dogs, plasma endogenous ACTH (eACTH) concentration was measured and adrenal gland size was assessed ultrasonographically. Measurements in the tumour-bearing dogs were taken prior to therapy. No difference existed in basal or ACTH-stimulated cortisol concentration between tumour-bearing and healthy dogs. No difference existed in eACTH concentration between dogs with non-haematopoietic neoplasia (NHN) and lymphoma. However, of 20 dogs with lymphoma, 15% had increased basal serum cortisol concentration, 5% had an exaggerated response to ACTH and 5% had an increased eACTH concentration. Of 15 dogs with NHN, 20% had increased basal cortisol concentration, 7% had an exaggerated ACTH response and no dogs had an increased eACTH concentration. Of the dogs with lymphoma and NHN, 5 and 13%, respectively, had decreased basal cortisol concentrations; 20% of dogs with lymphoma and 13% with NHN had a subnormal ACTH response. eACTH levels were below the reference range in 10% of dogs with lymphoma and 7% with NHN. Overall, 10 adrenal glands were enlarged in seven dogs, five with lymphoma and two with NHN. The clinical significance of these findings remains to be determined.

Ah Receptor-Mediated Impairment of Interrenal Steroidogenesis Involves StAR Protein and P450scc Gene Attenuation in Rainbow Trout

The objective of the study was to investigate the impact of aryl hydrocarbon receptor (AhR) activation on interrenal steroidogenesis in rainbow trout. To this end, fish were fed AhR agonist (beta-naphthoflavone (BNF): 10 mg/kg body mass/day) and antagonist (alpha-naphthoflavone (ANF): 10 mg/kg body mass/day) either singly or in combination (ABNF) for 5 days to elucidate the mechanisms involved in AhR-mediated depression of cortisol production. Liver AhR protein expression was significantly elevated only with ABNF, but not with BNF and ANF compared to the control group. However, all three treatments (BNF, ANF, and ABNF) significantly elevated cytochrome P450 1A1 (CYP1A1) gene and protein expression in the kidney and liver, respectively. Also, these three treatment groups had significantly depressed ACTH-stimulated cortisol production in vitro compared to the control group. This attenuation of interrenal steroidogenesis corresponded with a lower mRNA abundance of steroidogenic acute regulatory (StAR) protein and cytochrome P450 cholesterol side chain cleavage enzyme (P450scc), but not 11beta-hydroxylase. Furthermore, in vitro incubation of head kidney pieces with 7-3H-pregnenolone failed to show any treatment effects on pathways downstream of P450scc, except for a significantly higher conversion to progesterone in the BNF and ANF groups. Plasma cortisol and glucose levels showed no significant change between the treated groups and control, but liver and brain glucocorticoid receptor (GR) protein expression was higher in the BNF group, and ANF abolished this response. Taken together, both BNF and ANF impaired cortisol production, and the mechanism may involve attenuation of StAR and P450scc, the rate limiting steps in steroidogenesis. Overall, endocrine disruption by xenobiotics acting via AhR includes impaired cortisol biosynthesis and abnormal cortisol target tissue GR responses in rainbow trout.

Circulating adrenocorticotropic hormone (ACTH) and cortisol concentrations in normal, appropriate-for-gestational-age newborns versus those with sepsis and respiratory distress: cortisol response to low-dose and standard-dose ACTH tests

In this crossover study, we compared the peak responses of cortisol to low-dose (1 μg/1.73 m 2) and standard-dose (250 μg/1.73 m 2) adrenocorticotropic hormone (ACTH) stimulation tests in 90 full-term newborns (37 to 42 weeks gestational age, birthweight > 2,500 g, aged 4 to 7 days): 30 with sepsis syndrome, 30 with respiratory distress (RD) and 30 normal infants. Basal cortisol and ACTH were measured in a fasting venous sample. Serum cortisol concentrations were measured 30 minutes after low-dose ACTH and 60 minutes after standard-dose ACTH by radioimmunoassay (RIA). The mean basal circulating cortisol concentration and peak cortisol responses to low-dose and standard-dose ACTH tests were higher in stressed infants with sepsis and RD compared to normal. Basal but not ACTH-stimulated cortisol concentrations were significantly higher in newborns with sepsis versus those with RD. Circulating cortisol concentrations after the low-dose ACTH test were correlated significantly with those obtained after the standard-dose ACTH test ( r = 0.814, P < .001). Clinical subgrouping of septic newborns showed that those with leukopenia (5/10 died) and with meningitis (6/12 died) had significantly lower basal and peak cortisol responses to the low-dose ACTH test (but not the standard-dose ACTH test) versus those with leukocytosis (3/20 died) and without meningitis (2/18 died), respectively. In addition, septic newborns who died had significantly lower circulating cortisol concentrations and lower cortisol responses to the low-dose ACTH test (but not the standard-dose test) versus those who survived the stress. On an individual basis, only 2 septic newborns (both died) had low basal cortisol levels (<5 μg/dL) and cortisol responses less than 15 μg/dL after the low-dose ACTH test. Four more septic newborns had basal cortisol above 5 μg/dl but cortisol responses below 20 μg/dL after the low-dose ACTH test. These 4 newborns (4/30) with inadequate adrenocortical response to low-dose ACTH during sepsis had high mortality (3/4 died) and represented a subgroup of septic newborns that should be diagnosed, using a low-dose ACTH test, and treated early. These data suggest that the low-dose ACTH test may be more disciminatory than the standard-dose test among babies under stress. Increasing the cut-point level of basal cortisol in stressed infants to the lowest level of cortisol response to low-dose ACTH in normal newborns, followed by the use of a low-dose ACTH test, appears to select some newborns who need and may improve on corticosteroid therapy. Further studies are required to investigate whether supplementation with stress doses of hydrocortisone may improve the outcome in these patients.