Plasma Adrenocorticotropic Hormone Concentrations Research Articles

Investigation of rhythms of secretion and repeatability of plasma adrenocorticotropic hormone concentrations in healthy horses and horses with pituitarypars intermediadysfunction

There is little published information on whether measurement of plasma ACTH concentration at a single timepoint is a repeatable indicator of pituitary pars intermedia dysfunction (PPID). To determine whether ultradian or circadian fluctuations in ACTH production influence plasma ACTH concentration in normal horses and horses with PPID. Prospective observational study. Plasma ACTH concentration in 8 non-PPID horses and 8 horses with PPID was measured at 08.00, 11.00, 14.00 and 17.00 h on 5 nonconsecutive days within a 3 week period. In addition, at 08.30 h on one day, 6 samples were collected from each horse at precisely 5 min intervals over a period of 25 min. Descriptive and graphical analysis was performed and a linear mixed effects model was fitted to assess the effect of time of day on ACTH concentration in non-PPID and PPID horses. Evidence of ultradian fluctuation in ACTH production was not identified in either non-PPID or PPID horses. Evidence for circadian fluctuation was identified in non-PPID horses; plasma ACTH concentrations were highest at 08.00 h and decreased through the day. There was no evidence of circadian fluctuation in PPID horses. In non-PPID horses, the magnitude of circadian changes in ACTH concentration was smaller than variations in concentration that occurred at random. Intrahorse variability of ACTH concentration was greater in PPID horses than in non-PPID horses. Ultradian and circadian fluctuations in ACTH concentration are unlikely to influence clinical decision making; however, variations of potential clinical relevance do occur in individual horses, for reasons that remain to be determined, and increase in magnitude with progression of PPID. Results of the current study indicate that when an ACTH concentration between 19 and 40 pg/ml is measured, further testing should be considered to increase the accuracy of PPID diagnosis.

Periodic hypokalemia associated with cyclic Cushing's syndrome.

A 69-year-old woman presented with periodic hypertension, edema, and hypokalemia that occurred within an interval of a few weeks. Her laboratory test values showed autonomously elevated plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations. The patient's Cushingoid features were not evident on first admission. Several weeks later, in spite of constant oral potassium supplementation, severe hypokalemia recurred with Cushingoid features and worsening symptoms of leg edema and pigmentation, which spontaneously disappeared within a few days. Her periodic symptoms occurred in parallel with fluctuations of plasma ACTH and cortisol concentrations. A series of endocrinological and pituitary imaging findings led to a tentative diagnosis of cyclic Cushing's syndrome caused by ectopic ACTH secretion. However, chest and abdominal computed tomography did not reveal any candidate lesion. The patient's periodic hypercortisolemia and symptoms were well controlled after treatment with metyrapone plus dexamethasone. This is a very rare case of periodic hypokalemia and hypertension caused by cyclic Cushing's syndrome.

Changes in blood parameters and electroencephalogram of cattle as affected by different stunning and slaughter methods in cattle

The present study aimed to provide a comparative analysis of the effects of penetrative stunning, non-penetrative stunning and post-slaughter stunning on biochemical parameters and electroencephalogram (EEG) associated with stress in heifers and steers. Ten animals were assigned to each of the following four treatment groups: (1) animals were subjected to conventional halal slaughter (a clean incision through the structures on the ventral neck at the approximate level of vertebrae C2–C3 – the trachea, oesophagus, carotid arteries and jugular veins) and post-cut penetrating mechanical stun within 10–20 s of the halal cut (U); (2) high-power non-penetrating mechanical stunning using a mushroom-headed humane killer, followed by conventional halal slaughter (HPNP); (3) low-power non-penetrating mechanical percussive stunning using a mushroom-headed humane killer, followed by conventional halal slaughter (LPNP); and (4) penetrative stunning using a captive-bolt pistol humane killer, followed by conventional halal slaughter (P). For each animal, blood samples and electroencephalogram recordings were taken before stunning, post-stunning (if applicable) and post-slaughter, and plasma concentrations of cortisol, adrenocorticotrophic hormone (ACTH), adrenaline, noradrenaline and β-endorphin were determined. Irrespective of the stunning method, except for percentage change in plasma concentrations of noradrenaline, the values of blood parameters attained before and after stunning were not significantly different. The plasma noradrenaline concentration of the HPNP animals was significantly elevated following stunning. Following slaughter, the percentage change of plasma ACTH concentration in the P animals was significantly elevated. Neither stunning method nor sampling time had a significant effect on plasma β-endorphin concentration. On the basis of the EEG results, penetrative stunning seemed to be better in maximising the possibility of post-stunning insensibility, whereas U animals appeared to demonstrate an evident increase in EEG activity which is consistent with the presence of post-slaughter noxious stimuli associated with tissue cut and injury. The U animals had consistently higher, if not the highest, RMS values than did other stunned animals. This indicates a degree of EEG changes associated with stress and pain. On the basis of EEG data, our results suggested that penetrative stunning would be the most reliable method of ensuring insensibility and minimising pain. However, at slaughter, the P animals showed a dramatic elevation in the percentage change of circulating ACTH, suggesting physiological stress response. On a cautionary note, the results are not unequivocal, and it may be that the range of analyses available to researchers at this point of time are not sufficiently specific to allow definitive conclusions to be drawn.

Effects of sleep deprivation on autonomic and endocrine functions throughout the day and on exercise tolerance in the evening

The aim of this study was to investigate the effects of sleep deprivation on autonomic and endocrine functions during the day and on exercise tolerance in the evening. Ten healthy young males completed two, 2-day control and sleep deprivation trials. For the control trial, participants were allowed normal sleep from 23:00 to 07:00 h. For the sleep deprivation trial, participants did not sleep for 34 h. Autonomic activity was measured from 19:00 h on day 1 to 16:00 h on day 2 by frequency-domain measures of heart rate variability. Endocrine function was examined by measuring adrenocorticotropic hormone and cortisol from venous blood samples collected on day 2 at 09:00, 13:00, and 17:00 h and immediately after an exercise tolerance testing. Autonomic regulation, particularly parasympathetic regulation estimated from the high-frequency component of heart rate variability analysis, was significantly higher in the sleep deprivation trial than in the control trial in the morning and afternoon of day 2. Plasma adrenocorticotropic hormone concentrations were significantly higher at 09:00 and 13:00 h of day 2 under sleep deprivation. Heart rate during exercise was significantly lower following sleep deprivation. Therefore, the effects of sleep deprivation on autonomic regulation depend on the time of the day.

ACTH and cortisol cord plasma concentrations in preterm and term infants

To measure the adrenocorticotropic hormone (ACTH) and cortisol (F) cord plasma levels in preterm and term infants in relation to their mode of delivery. We studied 180 newborns appropriate for gestational age (GA) with birth weights between 365 and 4380 g and GAs between 21 and 41 weeks divided into three groups: born by vaginal delivery (VD), elective cesarean section (ECS) and emergency cesarean section (EMCS). ACTH and F levels were valued with enzyme-linked immunosorbent assay testing. Median concentrations were compared between groups by Student's T-test for independent and paired data. Multiple regression analysis was used to investigate the effect of GA on F and ACTH concentrations. A significant positive correlation between GA and plasma concentrations of ACTH (P<0.05) was found in the whole population, but not between GA and F (P=NS). A significant positive correlation was found between GA and plasma concentrations of both ACTH (P=0.01) and F (P=0.03) in VD. In those born by ECS, we demonstrated a positive correlation not only between plasma concentrations of ACTH (P=0.0000) and F (P=0.00002), respectively, with GA, but also a correlation between ACTH and F (P=0.0004). No significant correlations were found in the EMCS group (P=NS). Our results suggest simultaneous pituitary-adrenal maturation, which is complete only at term. The responsiveness of preterm babies to different stressful stimulations is similar to the terms' but quantitatively lower, and the secretion of ACTH and F may not suffice in severe pathological circumstances.

Letter to the Editor Adrenal function and MC1R gene analysis in a prepubertal girl with generalized hyperpigmentation:

Letter to the Editor Adrenal function and MC1R gene analysis in a prepubertal girl with generalized hyperpigmentation:

Aldosterone synthase inhibition in humans

Aldosterone synthase (CYP11B2) inhibition has emerged as a new option for the treatment of hypertension, heart failure and renal disorders, in addition to mineralocorticoid receptor (MR) blockade. The aim is to decrease aldosterone concentrations in both plasma and tissues, thereby decreasing MR-dependent and MR-independent effects in the cardiac, vascular and renal target organs. LCI699 was the first orally active aldosterone-synthase inhibitor to be developed for human use. Its structure is similar to that of FAD286, the dextroenantiomer of the aromatase inhibitor, fadrozole. It dose-dependently decreases plasma and urine aldosterone concentrations by up to 70 or 80% and increases plasma renin activity in healthy male subjects on a low-sodium diet. LCI699 does not decrease basal plasma cortisol concentrations at doses of 0.5-3 mg q.d., but it blocks the cortisol response to adrenocorticotropic hormone (ACTH) at doses ≥ 3 mg q.d. In a proof-of-concept study in patients with primary aldosteronism (PA), LCI699 (0.5-1 mg b.i.d.) induced a dose-dependent and reversible 70-80% decrease in plasma and urinary aldosterone concentration accompanied by a massive dose-dependent accumulation of deoxycorticosterone (>+700%), the aldosterone precursor, in the plasma, thereby confirming the inhibition of the CYP11B2 gene product. This effect was associated with a rapid correction of hypokalaemia, a modest decrease in blood pressure (BP) and a mild increase in plasma renin concentration in patients with PA. LCI699 administration induced biological signs of partial inhibition of the glucocorticoid axis, such as dose-dependent increases in both plasma ACTH and 11-deoxycortisol (the precursor of cortisol) concentrations, consistent with the inhibition of the CYP11B1 gene product. An 8-week placebo-controlled dose-response study on patients with Stage 1 and 2 essential hypertension reported an optimal decrease in BP with a dose of 1 mg LCI699 q.d., which had an antihypertensive effect similar to that of 50 mg b.i.d. eplerenone. A blunted cortisol response to ACTH was observed in 20% of patients, but the clinical and biological safety and tolerability of LCI699 were similar to those of placebo and eplerenone. The discovery of this first orally active aldosterone synthase inhibitor, LCI699, has provided new opportunities to assess the feasibility and the haemodynamic, biological and safety consequences as well as the limitations of this new approach to block the aldosterone pathway in hypertensive patients. However, as the effects of LCI699 on the glucocorticoid axis limit the use of higher doses range because of the loss of selectivity for CYP11B2, this aldosterone synthase inhibitor cannot replace the MR blockade in patients with hypertension, other cardiovascular or renal disorders. The development of second-generation aldosterone synthase inhibitors with a higher selectivity index for CYP11B2 than LCI699 should make it possible to test this approach at much higher doses in these patients, after the necessary toxicology and Phase I studies.

Design, Synthesis, and Structure–Activity Relationships of Novel Pyrazolo[5,1-b]thiazole Derivatives as Potent and Orally Active Corticotropin-Releasing Factor 1 Receptor Antagonists

This paper describes the design, synthesis, and structure-activity relationships of a novel series of 7-dialkylamino-3-phenyl-6-methoxy pyrazolo[5,1-b]thiazole derivatives for use as selective antagonists of the corticotropin-releasing factor 1 (CRF(1)) receptor. The most promising compound, N-butyl-3-[4-(ethoxymethyl)-2,6-dimethoxyphenyl]-6-methoxy-N-(tetrahydro-2H-pyran-4-yl)pyrazolo[5,1-b][1,3]thiazole-7-amine (6t), showed high affinity (IC(50) = 70 nM) and functional antagonism (IC(50) = 7.1 nM) for the human CRF(1) receptor as well as dose-dependent inhibition of the CRF-induced increase in the plasma adrenocorticotropic hormone (ACTH) concentration at a dose of 30 mg/kg (po). Further, in the light/dark test in mice, the compound 6t showed anxiolytic activity at a dose of 30 mg/kg (po).

Inappropriately normal plasma ACTH and cortisol concentrations in the face of increased circulating interleukin-6 concentration in exercise in patients with sarcoidosis

Sarcoidosis is an autoimmune disease, and hypothalamic–pituitary–adrenal (HPA) axis activity is blunted in autoimmunity. Exercise stimulates the HPA axis, and we hypothesized that in sarcoidosis patients responses to treadmill exercise would be reduced. Hence, we studied 44 sarcoidosis patients [27 untreated (age, mean ± SD, 42 ± 2 years, 12 males, 15 females) and 17 dexamethasone treated (age, 46 ± 4 years, 7 males, 10 females)] and 20 healthy controls (40 ± 5 years old, 9 males, 11 females). Blood samples were drawn before, at peak (exhaustion), and 15 min after treadmill exercise for adrenocorticotropic hormone (ACTH), cortisol, tumor necrosis factor (TNF), interleukin-1β (IL-1β) and IL-6 measurements. At peak, plasma ACTH (pg/ml) was increased in untreated (mean ± SE, ΔACTH = 162.8 ± 29.9) and treated (ΔACTH = 123.3 ± 48.1) patients and controls (ΔACTH = 112.3 ± 41.7). Post-exercise, cortisol (ng/ml) was increased (p < 0.05) in untreated patients (Δcortisol = 48.4 ± 14.7) and controls (Δcortisol = 46.0 ± 15.9), but not significantly in treated patients (Δcortisol = 1.43 ± 2.56). At baseline, serum IL-6 (pg/ml) and TNF (pg/ml) were higher in untreated (3.02 ± 0.54 and 3.89 ± 0.72) and treated (1.75 ± 0.33 and 2.16 ± 1.00) patients, respectively, than in controls (0.80 ± 0.66 and 1.58 ± 0.32). At peak exercise, IL-6 was increased in untreated (ΔIL-6 = 0.96 ± 0.14) and treated (ΔIL-6 = 0.91 ± 0.47) patients and controls (ΔIL-6 = 0.96 ± 0.18); IL-1β was increased only in controls. Hence, the HPA axis of untreated sarcoidosis patients and controls responded similarly to treadmill exercise. In sarcoidosis patients, increased IL-6 was associated with HPA stimulation. Cortisol concentrations were similar between patients and controls, although IL-6 concentrations were higher in patients. Thus, in the face of chronically elevated IL-6 levels in sarcoidosis, there may be dysfunctional IL-6-induced HPA responses or HPA adaptation to high IL-6 concentrations.

Photoperiod Regulates Corticosterone Rhythms by Altered Adrenal Sensitivity via Melatonin-Independent Mechanisms in Fischer 344 Rats and C57BL/6J Mice

Most species living in temperate zones adapt their physiology and behavior to seasonal changes in the environment by using the photoperiod as a primary cue. The mechanisms underlying photoperiodic regulation of stress-related functions are not well understood. In this study, we analyzed the effects of photoperiod on the hypothalamic-pituitary-adrenal axis in photoperiod-sensitive Fischer 344 rats. We first examined how photoperiod affects diurnal variations in plasma concentrations of adrenocorticotropic hormone (ACTH) and corticosterone. ACTH levels did not exhibit diurnal variations under long- and short-day conditions. On the other hand, corticosterone levels exhibited a clear rhythm under short-day condition with a peak during dark phase. This peak was not observed under long-day condition in which a significant rhythm was not detected. To analyze the mechanisms responsible for the photoperiodic regulation of corticosterone rhythms, ACTH was intraperitoneally injected at the onset of the light or dark phase in dexamethasone-treated rats maintained under long- and short-day conditions. ACTH induced higher corticosterone levels in rats examined at dark onset under short-day condition than those maintained under long-day condition. Next, we asked whether melatonin signals are involved in photoperiodic regulation of corticosterone rhythms, and rats were intraperitoneally injected with melatonin at late afternoon under long-day condition for 3 weeks. However, melatonin injections did not affect the corticosterone rhythms. In addition, photoperiodic changes in the amplitude of corticosterone rhythms were also observed in melatonin-deficient C57BL/6J mice, in which expression profiles of several clock genes and steroidgenesis genes in adrenal gland were modified by the photoperiod. Our data suggest that photoperiod regulates corticosterone rhythms by altered adrenal sensitivity through melatonin-independent mechanisms that may involve the adrenal clock.

The involvement of noradrenergic mechanisms in the suppressive effects of diazepam on the hypothalamic-pituitary-adrenal axis activity in female rats

AimTo elucidate the involvement of noradrenergic system in the mechanism by which diazepam suppresses basal hypothalamic-pituitary-adrenal (HPA) axis activity.MethodsPlasma corticosterone and adrenocorticotropic hormone (ACTH) levels were determined in female rats treated with diazepam alone, as well as with diazepam in combination with clonidine (α2-adrenoreceptor agonist), yohimbine (α2-adrenoreceptor antagonist), alpha-methyl-p-tyrosine (α-MPT, an inhibitor of catecholamine synthesis), or reserpine (a catecholamine depleting drug) and yohimbine.ResultsDiazepam administered in a dose of 2.0 mg/kg suppressed basal HPA axis activity, ie, decreased plasma corticosterone and ACTH levels. Pretreatment with clonidine or yohimbine failed to affect basal plasma corticosterone and ACTH concentrations, but abolished diazepam-induced inhibition of the HPA axis activity. Pretreatment with α-MPT, or with a combination of reserpine and yohimbine, increased plasma corticosterone and ACTH levels and prevented diazepam-induced inhibition of the HPA axis activity.ConclusionThe results suggest that α2-adrenoreceptors activity, as well as intact presynaptic noradrenergic function, are required for the suppressive effect of diazepam on the HPA axis activity.

Morphine Withdrawal Activates Hypothalamic-Pituitary-Adrenal Axis and Heat Shock Protein 27 in the Left Ventricle: The Role of Extracellular Signal-Regulated Kinase

The negative affective states of withdrawal involve the recruitment of brain and peripheral stress circuitry [e.g., noradrenergic activity, induction of the hypothalamo-pituitary-adrenocortical (HPA) axis, and the expression and activation of heat shock proteins (Hsps)]. The present study investigated the role of extracellular signal-regulated protein kinase (ERK) and β-adrenoceptor on the response of stress systems to morphine withdrawal by the administration of [amino[(4-aminophenyl)thio]methylene]-2-(trifluoromethyl)benzeneacetonitrile (SL327), a selective inhibitor of ERK activation, or propranolol (a β-adrenoceptor antagonist). Dependence on morphine was induced by a 7-day subcutaneous implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by the injection of naloxone (2 mg/kg s.c.). Plasma concentrations of adrenocorticotropin and corticosterone were determined by radioimmunoassay; noradrenaline (NA) turnover in left ventricle was determined by high-performance liquid chromatography; and catechol-O-methyl transferase (COMT) and Hsp27 expression and phosphorylation at Ser82 were determined by quantitative blot immunolabeling. Morphine-withdrawn rats showed an increase of NA turnover and COMT expression in parallel with an enhancement of adrenocorticotropin and plasma corticosterone concentrations. In addition, we observed an enhancement of Hsp27 expression and phosphorylation. Pretreatment with SL327 or propranolol significantly reduced morphine withdrawal-induced increases of plasma adrenocorticotropin and Hsp27 phosphorylation at Ser82 without any changes in plasma corticosterone levels. The present findings demonstrate that morphine withdrawal is capable of inducing the activation of HPA axis in parallel with an enhancement of Hsp27 expression and Hsp27 phosphorylation at Ser82 and suggest a role for β-adrenoceptors and ERK pathways in mediating morphine-withdrawal activation of the HPA axis and cellular stress response.

Prevalence, risk factors and clinical signs predictive for equine pituitary pars intermedia dysfunction in aged horses

Equine pituitary pars intermedia dysfunction (PPID) is an ageing-related neurodegenerative disorder. The prevalence and risk factors for PPID using seasonally adjusted basal adrenocorticotropic hormone (ACTH) concentrations in aged horses have not been previously reported. To determine the prevalence, risk factors and clinical signs predictive for PPID in a population of horses aged ≥ 15 years in Queensland, Australia. Owner-reported data was obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners were visited and a veterinary physical examination performed on all horses aged ≥ 15 years. Blood samples were analysed for basal plasma alpha melanocyte-stimulating hormone (α-MSH) and ACTH concentrations, routine haematology and selected biochemistry. Aged horses with elevations above seasonally adjusted cut-off values for basal plasma ACTH were considered positive for PPID. Positive horses were compared with their aged counterparts to determine risk factors and clinical signs associated with PPID. Pituitary pars intermedia dysfunction was prevalent in aged horses (21.2%) despite owners infrequently reporting it as a known or diagnosed disease or disorder. Numerous clinical or historical signs were associated with an increased risk of PPID in the univariable model, but only age (odds ratio (OR) 1.18; 95% confidence interval (CI) 1.11-1.25, P<0.001) and owner-reported history of hirsutism (OR 7.80; 95% CI 3.67-16.57, P<0.001) remained in the final multivariable model. There were no routine haematological or biochemical variables supportive of a diagnosis of PPID. Pituitary pars intermedia dysfunction occurs commonly in aged horses despite under-recognition by owners. The increased risk of PPID with age supports that this is an ageing associated condition. Aged horses with clinical or historical signs consistent with PPID, especially owner-reported hirsutism (delayed shedding and/or long hair coat), should be tested and appropriate treatment instituted.

Evaluation of basal plasma α‐melanocyte‐stimulating hormone and adrenocorticotrophic hormone concentrations for the diagnosis of pituitary pars intermedia dysfunction from a population of aged horses

The sensitivity and specificity of basal plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) has not been evaluated in a population-based study. To evaluate basal plasma α-MSH and ACTH concentrations for the diagnosis of PPID in a population of horses aged ≥ 15 years. Owner-reported data were obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners was visited and veterinary examination performed on horses aged ≥ 15 years. Blood samples were analysed for plasma α-MSH and ACTH concentrations. Seasonally adjusted cut-off values for α-MSH and ACTH concentrations for the diagnosis of PPID were obtained using Youden index values against a clinical gold standard diagnosis (hirsutism plus 3 or more clinical signs of PPID). α-melanocyte-stimulating hormone and ACTH were highly correlated with each other and with clinical and historical indicators of PPID. The increase in both α-MSH and ACTH with increasing numbers of clinical signs in affected horses supports a spectrum of disease. Both variables were affected by season, with derived cut-off values being higher in autumn compared with other seasons. Sensitivity and specificity were moderate and good in nonautumn seasons (59 and 93%, respectively) for α-MSH using a cut-off of 52.0 pmol/l. Sensitivity and specificity were good in nonautumn seasons (80 and 83%, respectively) for ACTH using a cut-off of 29.7 pg/ml. For both α-MSH and ACTH, sensitivity and specificity were close to 100% for samples obtained during the autumn period. Basal plasma α-MSH and ACTH had moderate-to-good sensitivity and specificity for the diagnosis of PPID, which improved substantially during the autumn period, suggesting this may be the ideal time to test. Further studies to develop seasonally adjusted reference intervals for different geographical locations are warranted.

Multiple pharmacological actions of Yiqi Huatan Decoction (益气化痰方) in a model of depression in rats

To investigate the influence of Yiqi Huatan Decoction (, YHD) on a model of depression in rats under different pathological conditions. Thirty-two male SD rats were randomly divided into 4 groups of 8: normal, model, YHD, and maprotiline. The model group, YHD group and maprotiline group used separate feeding and rats were exposed to chronic and unpredictable stress to build the depression model. From day 2, the YHD group and maprotiline group were respectively given YHD (7 g/kg) and maprotiline (10 mg/kg) by gastrogavage once daily. The normal and model groups were given the same volume of drinking water. The medication duration were 21 days. At the end of the experiment, the serum levels of copper and zinc were determined by atomic absorption spectroscopy, plasma concentrations of adrenocorticotropic hormone (ACTH) and cortisol (COR) were detected by radioimmunoassay, and levels of norepinephrine (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) in the hypothalamus were analysed by high performance liquid chromatography-eletricochemistry. Compared with the content of copper and zinc in the serum of rats in the normal group, serum copper levels in model rats were significantly increased and zinc content was significantly reduced (both P<0.05). Plasma concentrations of ACTH and COR in the model group were significantly increased compared with those in the normal group (P<0.05, P<0.01). The contents of NE, DA, and 5-HT in the hypothalamus of rats in the model group were significantly reduced compared with those of the normal group (P<0.05 or P<0.01). Compared with those in the model group, the serum copper content and plasma concentrations of ACTH and COR were significantly decreased (all P<0.05); meanwhile, serum zinc content and hypothalamic contents of NE, DA, and 5-HT were significantly increased in rats of the YHD group (all P<0.05). The same effects were also shown in the maprotiline group except for 5-HT (all P<0.05) The pharmacological actions of YHD for depression might be related to improving trace-element anomalies, reversing endocrine dysfunction, and modulating the disorders of monoaminergic neurotransmitters.

Comparison of serum cortisol measurement by immunoassay and liquid chromatography-tandem mass spectrometry in patients receiving the 11β-hydroxylase inhibitor metyrapone

Monaghan et al. present convincing data that serum cortisol results derived from a commonly used immunoassay must be interpreted with great caution in metyrapone-treated patients, given the findings of their extensive method comparison study using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These data support conclusions from previous publications which invoke cross-reactivity with cortisol precursors generated by the metyrapone blockade of the cortisol biosynthetic pathway. 11-Deoxycortisol (11DOC) is a likely candidate, and Monaghan et al. show a modest correlation between 11DOC and the difference between the immunoassay and the LC-MS/MS (Pearson’s correlation coefficient of 0.47). The authors state that variation in the data is so great that the assay bias cannot be corrected for by a knowledge of either the metyrapone dose or the serum 11DOC concentration. Based on previous data from a series of metyrapone-treated patients, we support this finding and further concluded that interference from 11DOC alone could not account for the difference between the serum cortisol immunoassay and LC-MS/MS results. We also showed that this is a widespread problem as three commonly used cortisol immunoassays are affected. Initially, we calculated the degree of 11DOC cross-reactivity for each of the cortisol assays by performing spiking studies with 11DOC. We then demonstrated in two metyraponetreated patients that the difference between the immunoassay and the LC-MS/MS serum cortisol results could not be entirely accounted for by the 11DOC concentration given the established cross-reactivity. Data presented in this abstract and unpublished data from additional local metyrapone-treated patients support the hypothesis of Monaghan et al. that this effect is most likely to be seen in adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome, as the degree of accumulation of steroid precursors is likely to be a function of both the magnitude of the ACTH drive and the extent of metyrapone blockade. In this way it is not dissimilar to congenital adrenal hyperplasia, where interference in serum cortisol immunoassays is also well described. If the data are available, it would be enlightening to see a correlation between the plasma ACTH concentration and the difference between the serum cortisol immunoassay and LC-MS/MS result in the cohort described in this paper, as well as cross-reactivity data for exogenous 11DOC. While the nature of the interference caused by metyrapone blockade in serum cortisol immunoassays remains elusive, we wholeheartedly support the conclusion of Monaghan et al. that current immunoassay methods for serum cortisol lack the specificity for use in metyrapone-treated patients, and this interference is likely to be more marked in patients with a high ACTH drive.

Antidiuretic response of a horse affected with pituitarypars intermediadysfunction to desmopressin acetate

Summary Central diabetes insipidus (DI) was diagnosed in a 20-year-old American Quarter Horse gelding that was concomitantly affected with pituitary pars intermedia dysfunction (PPID). The diagnosis of DI was supported by a positive response to administered desmopressin acetate. Diagnosis of PPID was supported by physical appearance and elevated plasma adrenocorticotropic hormone concentration following domperidone administration. The horse's physical condition improved following treatment with pergolide but long-term treatment with desmopressin was not undertaken and severe polyuria and polydipsia persisted. Desmopressin acetate appears to be useful for the diagnosis of DI in mature horses concomitantly affected with PPID.

Differential effects of etomidate and its pyrrole analogue carboetomidate on the adrenocortical and cytokine responses to endotoxemia*

We developed a novel pyrrole analog of etomidate, (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate), which retains etomidate's desirable anesthetic and hemodynamic properties but lacks its potent inhibitory affect on adrenocorticotropic hormone-stimulated steroid synthesis. The objective of this study was to test the hypothesis that in contrast to etomidate, carboetomidate neither suppresses the adrenocortical response to endotoxemia nor enhances the accompanying production of proinflammatory cytokines. Animal study. University research laboratory. Male Sprague-Dawley rats. For both single and multiple anesthetic dose studies, rats were injected with Escherichia coli lipopolysaccharide immediately followed by a hypnotic dose of etomidate, carboetomidate, or vehicle alone (dimethyl sulfoxide) as a control. For single-dose studies, no additional anesthetic (or vehicle) was administered. For multiple anesthetic dose studies, additional doses of anesthetic (or vehicle) were administered every 15 mins for a total of eight anesthetic (or vehicle) doses. Plasma adrenocorticotropic hormone, corticosterone, and cytokine concentrations were measured before lipopolysaccharide administration and intermittently throughout the 5-hr experiment. In single anesthetic dose studies, plasma adrenocorticotropic hormone and cytokine concentrations were not different at any time point among the etomidate, carboetomidate, and vehicle groups, whereas plasma corticosterone concentrations were briefly (60-120 mins) reduced in the etomidate group. In multiple anesthetic dose studies, plasma corticosterone concentrations were persistently lower and peak plasma interleukin-1β and interleukin-6 concentrations were higher in the etomidate group vs. the carboetomidate and control groups. Peak plasma interleukin-10 concentrations were similarly elevated in the etomidate and carboetomidate groups vs. the control group. Compared with etomidate, carboetomidate produces less suppression of adrenocortical function and smaller increases in proinflammatory cytokine production in an endotoxemia model of sepsis. These findings suggest that carboetomidate could be a useful alternative to etomidate for maintaining anesthesia for a prolonged period of time in patients with sepsis.

Pathophysiology of hypercortisolism in depression: pituitary and adrenal responses to low glucocorticoid feedback

To test three theories of hypercortisolemia in depression-hypothalamic overdrive, impaired glucocorticoid feedback, or autonomous cortisol production. We applied an overnight low-cortisol feedback strategy by administering metyrapone to hypercortisolemic depressed in-patients and control subjects. Under metyrapone, the increases of plasma adrenocorticotropic hormone (ACTH) concentrations and of basal and pulsatile ACTH secretion were not exaggerated in hypercortisolemic depressed patients compared with control subjects. ACTH approximate entropy (ApEn) did not differ at baseline or under metyrapone. Thus, neither hypothalamic overdrive nor irregular ACTH secretion was seen. We did not detect impaired cortisol feedback: the ACTH response was not reduced, and ApEn measures that are sensitive to feedback changes were comparable in both groups. Metyrapone disrupted cortisol secretory regularity in depressed and control subjects. On the baseline day, basal cortisol secretion was significantly increased and was highly irregular (high ApEn), and ACTH-cortisol cross-ApEn was markedly elevated in high-cortisol patients. Classical feed-forward overdrive and impaired feedback theories of hypercortisolemia in depression were not supported. Depressive hypercortisolemia may result from alternative pathophysiological mechanisms involving irregular basal hypersecretion of cortisol, associated with adrenal enlargement, possibly through splanchnic sympathetic activation of the adrenal cortex.

The Potential Role for Corticosterone in the Induction of Cleft Palate in Mice After Treatment With a Selective NK‐1 Receptor Antagonist, Casopitant (GW679769B)

Casopitant is a potent and selective NK-1 receptor antagonist that has shown clinical efficacy in the prevention of chemotherapy-induced and postoperative-induced nausea and vomiting. In an embryo-fetal development study, pregnant mice were given vehicle (sterile water) or doses of 30, 100, or 300 mg/kg/day casopitant on Gestation Day (GD) 6 to 15. Fetuses were evaluated for external, visceral, and skeletal abnormalities on GD 18. In a follow-on study to investigate casopitant-induced hormonal changes during the developmental period for palate formation, pregnant mice were given vehicle (sterile water) or 300 mg/kg/day casopitant once daily on GD 6 to 13. Blood was collected on GD 13 at various time-points for measurement of plasma adrenocorticotropic hormone and corticosterone (CRT) concentrations. There was no evidence of developmental toxicity in mice at 30 or 100 mg/kg/day but 9% of fetuses at 300 mg/kg/day had cleft palate. Mice are sensitive to glucocorticoid-induced cleft palates, and NK-1 antagonists are known to modulate the hypothalamic-pituitary-adrenal axis leading to increases in corticosterone. On GD 13, mean plasma adrenocorticotropic hormone levels at 300 mg/kg/day were elevated by approximately twofold from vehicle-treated levels at 1 hr post-dose and mean plasma CRT levels were elevated by 3, 5, and 10-fold at 0.5, 1, and 2 hr post-dose, respectively. The increased level of CRT was in the range previously shown in the literature to cause cleft palates in mice and was likely the underlying mechanism behind casopitant-induced cleft palate in mice.