Plasma ACTH Concentrations Research Articles

Changes in prolactin secretion in the short- and long-term after adrenalectomy

To evaluate the modulation of the hypothalamus-pituitary-adrenal axis (HPA) on prolactin secretion in rats after adrenalectomy (ADX). Plasma corticosterone, ACTH, and prolactin concentrations were measured by radioimmunoassay in rats after bilateral ADX in the short- (3 hours and 1 day) and long-term (3, 7, and 14 days). Animals that underwent ADX showed undetectable corticosterone levels and a triphasic ACTH response with a transient increase (3h), a decrease (1d), and further increase in the long-term after ADX. Sham animals showed a marked increase in corticosterone and ACTH levels three hours after surgery, with a decrease to basal levels thereafter. Plasma prolactin levels were not changed after ADX. There are different points of equilibrium in the HPA axis after the glucocorticoid negative feedback is removed. Prolactin plasma secretion is not altered in the short or long- term after ADX, suggesting that the peptidergic neurons essential for prolactin release are not activated after ADX.

A Study on the Effect of High Calorie Diet on Stress Alleviation

In this study, we tried to reveal the presence of a cytokine that is regulated by weight, food intake, body fat, the hypothalamus-pituitary-adrenal axis, and corticosterone. The experiment group was given a high calorie diet and the control group was fed a normal calorie diet, and both groups were exposed to various stresses. The behavioral and hormonal change by the kinds and severity of stresses were measured via their immunologic aspect as well as their stress alleviation by voluntary high calorie food intake. After sacrificing the animal, the adrenal gland fat tissues were weighed, and the high calorie diet group showed heavier adrenal glands than those of the control group. In particular, the CVS A group had lighter adrenal gland weight than the Res B and CVS B groups, and the other groups had heavier adrenal glands. The comparison of plasma ACTH concentration to the corticosteroid secretion ratio showed that the CVS A group had decreased ACTH and an increased corticosteroid/ACTH ratio. This fact shows that the adrenal gland was highly active and, in spite of a normal corticosteroid concentration, induced too much negative feedback inhibition.

Circadian and circannual rhythms of cortisol, ACTH, and α-melanocyte-stimulating hormone in healthy horses

Cosinor analysis was used to evaluate whether pituitary and adrenal hormones exhibit circadian rhythmicity in horses. The effect of season and animal age on their respective rhythms was also determined. In addition, the usefulness of evaluating cortisol rhythmicity for the diagnosis of pituitary pars intermedia dysfunction (PPID) was assessed. Serum cortisol concentrations (P < 0.01), but not plasma ACTH or α-melanocyte-stimulating hormone (α-MSH), showed a significant circadian periodicity in horses. An effect of season on hormone concentration was observed with plasma ACTH and α-MSH concentration greater in the fall and cortisol concentration greater in the spring (P < 0.001). Age did not affect cortisol rhythm, but it did blunt the variation in cortisol concentration in horses, similar to what has been previously reported to occur in aged people and dogs. In addition, our results suggest that clinically and diagnostically normal, non–PPID-affected horses commonly have a loss of cortisol diurnal rhythm. Therefore, measurement of circadian rhythm is not an appropriate diagnostic test for PPID.

Evidence suggesting that ghrelin O-acyl transferase inhibitor acts at the hypothalamus to inhibit hypothalamo-pituitary-adrenocortical axis function in the rat

Production of n-octanoyl-modified ghrelin (GHREL), an active form of the peptide requires prohormone processing protease and GHREL O-acyltransferase (GOAT), as well as n-octanoic acid. Recently a selective GOAT antagonist (GO-CoA-Tat) was invented and this tool was used to study the possible role of endogenous GHREL in regulating HPA axis function in the rat. Administration of GOAT inhibitor (GOATi) resulted in a notable decrease in plasma ACTH, aldosterone and corticosterone concentrations at min 60 of experiment. Octanoic acid (OA) administration had no effect on levels of studied hormones. Plasma levels of unacylated and acylated GHREL remained unchanged for 60min after either GOATi or OA administration. Under experimental conditions applied, no significant changes were observed in the levels of GOAT mRNA in hypothalamus, pituitary, adrenal and stomach fundus. After GOATi injection hypothalamic CRH mRNA levels were elevated at 30min and pituitary POMC mRNA levels at 60min. Both GOATi and OA lowered basal, but not K+-stimulated CRH release by hypothalamic explants and had no effect on basal or CRH-stimulated ACTH release by pituitary slices. Neither GOATi nor OA affected corticosterone secretion by freshly isolated or cultured rat adrenocortical cells. Thus, results of our study suggest that in the rat endogenous GHREL exerts tonic stimulating effect on hypothalamic CRH release. This effect could be demonstrated by administering rats with selected inhibitor of ghrelin O-acyltransferase, the enzyme responsible for GHREL acylation, a process which is absolutely required for both GHSR-1a binding and its central endocrine activities.

Changes in heart rate, heart rate variability, and atrioventricular block during withholding of food in Thoroughbreds

To determine whether withholding of food affects autonomic nervous system balance by analysis of heart rate (HR), HR variability (HRV), and frequency of second-degree atrioventricular block in horses. 5 healthy Thoroughbreds. For two 24-hour periods in a crossover study, food was withheld from horses or horses were maintained on their regular feeding schedule (control conditions) in their stalls and Holter monitor ECG recordings were obtained. The ECGs were analyzed by use of fast-Fourier transformation, and power spectrum densities were calculated for low-frequency (0.01 to 0.07 Hz) and high-frequency (0.07 to 0.6 Hz) variations in HR. Serum cortisol and plasma ACTH, norepinephrine, and glucose concentrations were measured at predetermined time points. Withholding of food resulted in significantly lower HR and more frequent second-degree atrioventricular block (the frequency of which was inversely related to the HR), compared with findings for control conditions. Circadian rhythms were similar during food-withholding and control conditions; peak HR was detected from 7:00 pm to 8:00 pm, and the lowest HR was detected in the early morning. During food-withholding conditions, the low-frequency and high-frequency components of HRV were significantly higher, and the low-frequency-to-high-frequency ratio was lower than during control conditions. Serum cortisol concentration was higher and plasma glucose concentration was lower at 6:00 pm in horses when food was withheld, compared with findings during control conditions. Indices of HRV seemed to be sensitive to changes in autonomic nervous activity and may be useful as clinical indices of the neuroendocrine response to stressors in horses.

Association of Adrenocorticotrophin and Cortisol Concentrations with Peripheral Blood Leukocyte Cytokine Gene Expression in Septic and Nonseptic Neonatal Foals

The hypothalamic-pituitary-adrenal (HPA) is influenced by the proinflammatory cytokines IL-6, IL-1β, and TNF-α in critically ill humans. Information about the association of cytokines with the HPA axis in neonatal foals is lacking. The objectives were to describe for hospitalized septic and nonseptic foals (1) temporal changes in blood concentrations of ACTH, and cortisol, and leukocyte cytokine gene expression, and (2) coassociation of these HPA axis hormones with blood leukocyte cytokine gene expression. Hospitalized septic foals (N = 15) and hospitalized nonseptic foals (N = 11). Blood samples, obtained from study foals at admission (T = 0), and 24 (T = 1), 48 (T = 2), 72 (T = 3), and 96 (T = 4) hours after admission, were processed to isolate RNA from leukocytes and to harvest plasma and serum for hormone assays. Plasma ACTH and serum cortisol concentrations were determined by radioimmunoassay. Leukocyte mRNA expression of IL-1β IL-6, IL-8, IL-10, and TNF-α was determined using RT-PCR. Cortisol concentrations were greater (P < .05) in foals at admission than at other time points. The expressions of IL-8 and IL-10 mRNA were lower (P < .05) at each time point in septic than in nonseptic foals. Among septic foals, ACTH was positively associated (P = .0026) with IL-6 mRNA expression. Sepsis influences secretion of the HPA axis hormones and expression of cytokines in foals. A positive association with the HPA axis and IL-6 expression was detected. The clinical importance of these findings requires additional study.

Control of hypothalamic–pituitary–adrenal stress axis activity by the intermediate conductance calcium‐activated potassium channel, SK4

The anterior pituitary corticotroph is a major control point for the regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the neuroendocrine response to stress. Although corticotrophs are known to be electrically excitable, ion channels controlling the electrical properties of corticotrophs are poorly understood. Here, we exploited a lentiviral transduction system to allow the unequivocal identification of live murine corticotrophs in culture. We demonstrate that corticotrophs display highly heterogeneous spontaneous action-potential firing patterns and their resting membrane potential is modulated by a background sodium conductance. Physiological concentrations of corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) cause a depolarization of corticotrophs, leading to a sustained increase in action potential firing. A major component of the outward potassium conductance was mediated via intermediate conductance calcium-activated (SK4) potassium channels. Inhibition of SK4 channels with TRAM-34 resulted in an increase in corticotroph excitability and exaggerated CRH/AVP-stimulated ACTH secretion in vitro. In accordance with a physiological role for SK4 channels in vivo, restraint stress-induced plasma ACTH and corticosterone concentrations were significantly enhanced in gene-targeted mice lacking SK4 channels (Kcnn4(-/-)). In addition, Kcnn4(-/-) mutant mice displayed enhanced hypothalamic c-fos and nur77 mRNA expression following restraint, suggesting increased neuronal activation. Thus, stress hyperresponsiveness observed in Kcnn4(-/-) mice results from enhanced secretagogue-induced ACTH output from anterior pituitary corticotrophs and may also involve increased hypothalamic drive, thereby suggesting an important role for SK4 channels in HPA axis function.

Apelin is involved in postprandial responses and stimulates secretion of arginine-vasopressin, adrenocorticotropic hormone, and growth hormone in the ruminant

Apelin and its mRNA are expressed in several tissues, including the supraoptic and paraventricular nuclei in the hypothalamus. Although apelin is reported to be involved in the regulation of fluid homeostasis, little is known about the postprandial dynamics of apelin in plasma and its regulatory effects on the anterior pituitary hormones of ruminants. Therefore, the aims of this study were to investigate the following: (1) changes in plasma apelin concentrations in response to food intake under conditions of hydration (free access to water) or dehydration (water restriction), and (2) the effects of intravenous administration of apelin on plasma concentrations of arginine-vasopressin (AVP), ACTH, GH, and insulin. In Experiment 1 with the use of goats, the postprandial plasma apelin concentration was significantly increased under the dehydration condition compared with the hydration condition, and this increase was accompanied by increased plasma concentrations of AVP and ACTH after 24 h of dehydration. In Experiment 2 with the use of sheep and hydration conditions, the intravenous administration of apelin ([Pyr1]-apelin-13; 0.5 mg/head) caused a tendency to increase or caused a significant increase in plasma concentrations of AVP, ACTH, GH, insulin, and glucose. On the basis of these findings, we concluded that apelin is involved in the feeding process, and it regulates endocrine functions in the anterior pituitary gland via AVP in ruminant animals.

Autonomous adrenocorticotropin reaction to stress stimuli in human fetus

The aim of the study was to determine whether human fetuses show ACTH response to stress stimuli, to define the gestational age from which these reactions may be present and to analyze the relationship between hormone concentrations and their changes, both in fetuses and in pregnant women. The study included 81 intrauterine transfusions carried out in 19 pregnant women. 52 procedures were performed directly into the umbilical vein, which is not innervated, so neutral for the fetus (the PCI group) and 29 transfusions into the intrahepatic vein —which puncture is stressful for the fetus (the IHV group). ACTH and cortisol concentrations in fetal and maternal plasma obtained during the procedures were assayed. The initial mean plasma ACTH concentration in the PCI group equaled 18.94pg/mL, but in the IHV group it was significantly higher and amounted 75.17pg/mL (p<0.001). There was no significant change in the hormone concentration during the transfusion both in the IHV group (95.8pg/mL, p>0.05) and in the PCI group (22.36pg/mL, p>0.05). The observed hormonal response in the IHV group proves the existence of fetal pituitary reaction to stress. The initial fetal ACTH concentration in the IHV group correlated with the number of transfusions performed on a single fetus (R=0.41; p=0.04). No correlation with parity, gestational weeks or the volume of transfused packed red blood cells was found. There was also no correlation between fetal and maternal ACTH concentrations in any group. Presented data suggest that the human fetus shows autonomous ACTH reaction to stress stimulation.

Involvement of orexin in the regulation of stress, depression and reward in alcohol dependence

There is growing evidence from preclinical studies for an involvement of orexins (ORX) in the regulation of stress, affectivity and addictive behavior. The aim of our study was to gather corresponding clinical data and to elucidate the relationships between alcohol withdrawal stress, ORX plasma concentration and psychopathology. A consecutive sample of thirty-four alcohol-dependent inpatients was included in the study. Blood was drawn at onset of withdrawal and following 2weeks of controlled abstinence in order to assess ORX, ACTH and cortisol plasma concentrations. In parallel, we assessed clinically relevant psychological distress symptoms applying the Brief Symptom Inventory (BSI). We found a significant positive correlation between ORX and global distress indices of the BSI (p≤0.05). In a regression model, ORX concentration during acute withdrawal explained 24% of the variance of symptom severity (p<0.01). No association with craving, ACTH or cortisol plasma concentration was detected. Our results suggest an involvement of ORX in the affective dysregulation seen commonly in alcohol dependent patients during alcohol withdrawal. Moreover, the effects on global distress indices as well as the earlier studied effects on reinstatement of drug seeking behaviors may point on an involvement of ORX in impaired brain stress systems.

Glucose Ingestion Selectively Amplifies ACTH and Cortisol Secretory-Burst Mass and Enhances Their Joint Synchrony in Healthy Men

Glucose intake is associated with a variable increase in adrenal glucocorticoid secretion. Glucose ingestion elevates cortisol secretion by 1) augmenting pulsatile ACTH release; and/or 2) enhancing ACTH-cortisol synchrony or dose-responsiveness. Fifty-eight healthy men ages 19-78 yr with computed tomography-estimated abdominal visceral fat participated in the study. The study was conducted at the Clinical Translational-Research Center and Veterans Affairs Medical Center. We conducted frequent sampling of plasma ACTH and cortisol concentrations after glucose vs. water ingestion in the fasting state, as well as deconvolution, approximate entropy, linear-regression, and dose-response analysis. After water ingestion, age was a negative correlate of the mass of ACTH (P = 0.009; R(2) = 0.119) and of cortisol (P < 0.001; R(2) = 0.269) secreted per burst. Glucose ingestion abolished both relationships but amplified pulsatile ACTH (P = 0.009) and cortisol (P = 0.001) secretion. Glucose exposure selectively augmented the mass of ACTH (P < 0.001) and of cortisol (P = 0.004) secreted per burst without altering burst number or basal secretion. The increment in pulsatile ACTH strongly predicted the increment in pulsatile cortisol (P < 10(-4); R(2) = 0.325) secretion. Abdominal visceral fat positively forecast the glucose-induced increment in cortisol secretory-burst mass (P = 0.019). According to approximate entropy analysis, glucose input also enhanced the joint synchrony of ACTH-cortisol secretory patterns (P ≤ 0.001). Caloric intake did not affect analytical dose-response estimates of ACTH potency and efficacy or adrenal sensitivity. Conjoint augmentation of the mass of ACTH and cortisol secreted per burst and enhancement of ACTH-cortisol synchrony underlie glucose-induced glucocorticoid secretion in healthy men. Visceral adiposity is a predictor of the glucose-stimulated increment in burst-like cortisol output, suggesting an additional possible mechanism for increased cardiovascular risk in abdominal obesity.

The Effect of Geographic Location, Breed, and Pituitary Dysfunction on Seasonal Adrenocorticotropin and α‐Melanocyte‐Stimulating Hormone Plasma Concentrations in Horses

Plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotropin (ACTH) concentrations in horses vary with season, confounding diagnostic testing for pituitary pars intermedia dysfunction (PPID). The goals of this study were to determine whether seasonal variation in plasma α-MSH and ACTH concentrations in horses is influenced by geographic location, breed, or PPID. Healthy light breed horses residing in Florida, Massachusetts, and Finland (n = 12 per group); healthy Morgan horses (n = 13); healthy ponies (n = 9) and horses with PPID (n = 8). Monthly plasma α-MSH and ACTH concentrations were measured by radioimmunoassay. Nonlinear regression analysis was used to estimate the time of peak hormone concentrations. Mean hormone concentrations in fall and nonfall months were compared. The fall peak plasma α-MSH concentration occurred earlier in horses residing at more northern locations. Mean seasonal α-MSH concentrations were similar in all healthy groups at all locations, but in the fall, plasma ACTH concentrations were higher in horses living in more southern locations. Plasma ACTH but not α-MSH concentrations were higher in Morgan horses compared with light breed horses from the same location. Hormone concentrations of ponies did not differ from those of horses during either season. Concentrations of both hormones were high in the fall compared with the spring in horses with PPID. These findings suggest geographic location of residence and breed may affect the onset, amplitude, or both of the seasonal peak of pars intermedia (PI) hormones and should be considered when performing diagnostic testing for PPID. Horses with PPID maintain seasonal regulation of PI hormone output.

A Role for Mineralocorticoid Receptors in the Physiology of the Ovine Fetus: Effects on ACTH and Lung Liquid Composition

In the human and ovine fetus, the presence of 11β-hydroxysteroid dehydrogenase 1 allows cortisol and other corticosteroids to act at mineralocorticoid receptors (MRs) in lung and brain. To test the physiologic role of MRs in the late gestation fetus, fetal lambs were infused with a specific MR antagonist for 12 h. Infusion of the MR antagonist significantly increased plasma ACTH and cortisol concentrations. Infusion of the MR antagonist also significantly increased fetal Pco2 and hematocrit, and decreased fetal pH, but did not alter fetal heart rate or blood pressure. Infusion of the MR antagonist altered the ratio of Na⁺ to K⁺ in lung fluid but did not alter the rate of production of lung liquid or the expression of the epithelial sodium channel α or of the Na,K ATPaseα1 in lung. These results suggest that corticosteroids act at MR to regulate ACTH and blood volume and modulate lung fluid composition in the fetus, but basal levels of corticosteroids do not alter lung liquid production rate through effects on MR.

Naloxone decreases the inhibitory effect of alprazolam on the release of adrenocorticotropin/cortisol induced by physical exercise in man.

• Alprazolam (ALP), a benzodiazepine activating GABAergic receptors, is involved in ACTH secretion. • This study demonstrates a partial opioid influence in the inhibitory effect of ALP on the release of ACTH/cortisol during physical exercise. To establish the possible involvement of alprazolam (ALP) and/or opiates in the mechanism underlying the ACTH/cortisol response to physical exercise. Tests were carried out under basal conditions (exercise control test), exercise plus ALP (50 µg at time -90 min), naloxone (10 mg at time 0) or ALP plus naloxone. Plasma ACTH and serum cortisol concentrations were evaluated in blood samples taken before, during and after the bicycle ergometer tests. ACTH and cortisol concentrations rose significantly after physical exercise. Maximum peak at time 15 min (P ≤ 0.01 vs. baseline) for ACTH and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol. In the presence of naloxone, the ACTH and cortisol responses were significantly increased (maximum peak at time 20 min, P ≤ 0.02 vs. control test for ACTH, and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol) whereas they were abolished by ALP. When ALP and naloxone were given together, the inhibitory effect of ALP was partial. These data demonstrate an inhibitory effect of ALP in the regulation of the ACTH/cortisol response to physical exercise in man and suggest that GABAergic receptor activating benzodiazepines and opioids interact in the neuroendocrine secretion of ACTH/cortisol.

Seasonal Changes in Plasma Adrenocorticotropic Hormone and α‐Melanocyte‐Stimulating Hormone in Response to Thyrotropin‐Releasing Hormone in Normal, Aged Horses

Results of diagnostic tests for equine pituitary pars intermedia dysfunction (PPID), including endogenous ACTH concentration and the overnight dexamethasone suppression test (DST), are affected by season. New and potentially more sensitive diagnostic tests for equine PPID, such as thyrotropin-releasing hormone (TRH)-stimulated ACTH response, have been developed, but have had limited evaluation of seasonality. Our purpose was to evaluate seasonal changes in plasma ACTH and alpha-melanocyte-stimulating hormone (α-MSH) responses to TRH administration. Nine, healthy, aged horses with normal DST results. Synthetic TRH (1 mg) was administered IV. Plasma ACTH and α-MSH concentrations were measured at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 180 minutes. Testing was performed in February, July, August, September, October, and November. Mean TRH-stimulated ACTH and α-MSH concentrations were compared across months and time by repeated measures analysis of variance. Significance was set at the P < .05 level. Concentrations of ACTH and α-MSH significantly increased after TRH administration. Endogenous and TRH-stimulated ACTH and α-MSH concentrations were significantly different across months with higher concentrations in the summer and fall compared with February. Plasma ACTH and α-MSH responses to TRH administration experience seasonal variation, with TRH-stimulated ACTH and α-MSH concentrations increasing from summer through fall. These results support previous evidence of a seasonal influence on the equine pituitary-adrenal axis. More research is warranted with a larger number of horses to determine if seasonal reference ranges for TRH stimulation testing need to be defined.

Endocrinological Differences between Hatano High- and Low-Avoidance Rats during Early Two-Way Avoidance Acquisition

Hatano high (HAA)- and low (LAA)-avoidance rats were selected from Sprague-Dawley rats genetically on the basis of their active avoidance behavior in a shuttle-box test. The purpose of this study was to investigate stress-related alterations of hormones corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP), prolactin, and adrenocorticotropin (ACTH) in the brain and blood during early avoidance acquisition using two lines of Hatano rats. In paraventricular nucleus (PVN) of the hypothalamus, the CRH levels in HAA rats were significantly increased after shuttle-box tasks compared with before the tasks, whereas the CRH levels in LAA rats significantly decreased after shuttle-box tasks compared with before the tasks. In the HAA rats, the CRH and AVP levels in the median eminence decreased after shuttle-box tasks, whereas there were no significant differences in the levels between before and after shuttle-box tasks in LAA rats. The plasma concentrations of ACTH were significantly higher in HAA rats than in LAA rats after shuttle-box tasks. These results show that the response of CRH-ACTH was higher in HAA rats than in LAA rats. This phenotype may be an important reason for the high avoidance rates of shuttle-box tasks in HAA rats. These endocrine differences in early avoidance acquisition may be involved in regulation of their avoidance responses in the shuttle-box task.

Altered Immunomodulation by Glucocorticoids in Neonatal Pigs Exposed to a Psychosocial Stressor

Stressful early life experiences can have short- and long-term effects on neuroendocrine and immune mechanisms of adaptation, which are primarily modulated by glucocorticoids. This study aimed to examine how the stress and immune systems interact to cope with psychosocial stress induced by a single social isolation (4 h) in neonatal pigs at 7, 21, or 35 d of age. This social isolation provoked increased plasma ACTH and cortisol concentrations and reduced TNF-α levels but had no significant effect on IL-6 levels. Socially isolated piglets had a higher lipopolysaccharide (LPS)-stimulated proliferative response of peripheral blood mononuclear cells (PBMCs) than controls, whereas concanavalin A (ConA)-induced proliferation was not affected by isolation. A single social isolation also induced a dose-dependent cortisol resistance in ConA- and LPS-stimulated PBMCs compared with controls, which may be an adaptive response in the short term. Moreover, LPS-stimulated cultures from control piglets showed a reduction in cortisol sensitivity with increasing age. Conclusively, these findings provide stress-related measures for the psychophysiological assessment of livestock handling practices but might also have implications for stress and health studies in young animals and humans.

The 83,557insA variant of the gene coding 11β-hydroxysteroid dehydrogenase type 1 enzyme associates with serum osteocalcin in patients with endogenous Cushing's syndrome

Objective The type 1 and type 2 isoenzymes of the 11β-hydroxysteroid dehydrogenase (HSD11B) play an important role in the prereceptor regulation of glucocorticoid bioavailability and action. The potential importance of gene variants coding HSD11B has not been previously evaluated in patients with endogenous hypercortisolism. The aim of the present study was to explore presumed associations between the 83,557insA variant of the HSD11B1 gene and circulating hormone concentrations, bone turnover and bone mineral density (BMD) in patients with endogenous Cushing's syndrome (CS). Patients and methods Forty one patients with ACTH-producing pituitary adenomas (Cushing's disease—CD), 32 patients with cortisol-producing adrenal tumors (ACS) and 129 healthy control subjects were genotyped for the 83,557insA variant of the HSD11B1 gene using restriction fragment length analysis. BMD was measured by dual-energy X-ray absorptiometry. Serum cortisol, ACTH, osteocalcin (OC) and C-terminal crosslinks (CTX) of human collagen type I (C-telopeptide) were measured by electrochemiluminescence immunoassay. Results No statistically significant differences were found in the allelic frequencies of the 83,557insA polymorphism among patients with CD, ACS and healthy controls. Among all patients with CS, heterozygous carriers of the 83,557insA had significantly higher serum OC as compared to non-carriers. Patients with ACS carrying the 83,557insA variant had higher plasma ACTH concentrations compared to non-carriers. The 83,557insA variant failed to associate with BMD in patients and controls. Conclusions Our present findings indicate that the 83,557insA variant of the HSD11B1 gene may influence serum markers of bone turnover, but not BMD in patients with endogenous Cushing's syndrome.

Relationship between corticotrophin and endorphin responses to a single bout of competitive swimming

The aims of this investigation were to determine the corticotrophin (ACTH) and endorphin (END) responses to a single bout of competitive swimming exercise and to examine the relationship between them. Plasma ACTH and ENDs concentrations were determined in 13 male swimmers at three time points: basal conditions, and before and after swimming competition (100 m freestyle). The results showed an END response to precompetition stress, since an increase in END plasma levels was observed (from 36.3±2.9 pg/ml assessed in basal conditions to 51.8±3.2 pg/ml, p≤0.01). However, ACTH plasma levels remained unchanged at this time-point (10.1±0.9 pg/ml and 10.9±1.2 pg/ml for basal conditions and precompetition respectively). After competitive swimming effort ACTH and END levels rose significantly, reaching values of 39.4±5.2 pg/ml and 128.6±18.1 pg/ml for ACTH and END, respectively, and showing statistical differences with precompetition (p≤0.001) and basal condition levels (p≤0.001). Significant correlations were found between ACTH and END levels both in precompetition (r=0.647; p≤0.05) and in postcompetition (r=0.725; p≤0.01). It is concluded that single bout of competitive swimming induces a psychological and physiological stress which stimulates the same pattern of response for ACTH and END.

Association of Season and Pasture Grazing with Blood Hormone and Metabolite Concentrations in Horses with Presumed Pituitary Pars Intermedia Dysfunction

Pituitary pars intermedia dysfunction (PPID) is a risk factor for pasture-associated laminitis, which follows a seasonal pattern. Hormonal responses to season differ between PPID and unaffected horses. Seventeen horses aged 8-30 years (14 horses ≥ 20 years of age). Longitudinal observational study. Blood was collected monthly from August 2007 until July 2008 after pasture grazing and again after overnight stall confinement. Blood hormone and metabolite concentrations were measured and pasture grass samples were analyzed to determine carbohydrate content. Analysis of variance analysis for repeated measures was performed. Mean ACTH concentrations varied significantly over time (P < .001), with higher concentrations detected in August, September, and October compared with November-April. Pasture × time effects were detected for glucose and insulin concentrations, with peaks observed in September. Horses were retrospectively allocated to PPID (n = 8) and control (n = 9) groups on the basis of plasma ACTH concentrations. Changes in insulin concentrations over time differed in the PPID group when compared with the control group. Insulin concentrations were positively correlated with grass carbohydrate composition. PPID did not affect the timing or duration of the seasonal increase in ACTH concentrations, but higher values were detected in affected horses. Insulin concentrations differed between groups, but hyperinsulinemia was rarely detected. Glucose and insulin concentrations peaked in September when horses were grazing on pasture, which could be relevant to the seasonal pattern of laminitis.