Effect of vitamin D3 supplementation on Staphylococcus aureus nasal carriage: a randomized, double-blind, placebo-controlled trial in healthy adults.

Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25OHD) concentrations and Staphylococcus aureus nasal carriage; however, clinical trials of vitamin D supplementation are lacking. To assess the effect of vitamin D3 supplementation on persistent S. aureus nasal carriage we conducted a randomized, double-blind, placebo-controlled trial among 322 healthy adults. Participants were given an oral dose of either 200 000 IU vitamin D3 for each of 2 months, followed by 100 000 IU monthly or placebo in an identical dosing regimen, for a total of 18 months. Nasal swabs for S. aureus culture and serum for 25OHD measurement were obtained at baseline, 6, 12 and 18 months of study. The mean baseline concentration of 25OHD was 72 nM (SD 22 nM). Vitamin D3 supplementation increased 25OHD levels which were maintained at >120 nM throughout the study. Nasal colonization by S. aureus was found in 31% of participants at baseline. Persistent carriage, defined as those that had positive S. aureus nasal cultures for all post-baseline swabs, occurred in 20% of the participants but vitamin D3 supplementation was not associated with a reduction in persistent carriage (OR = 1.39, 95% CI 0.63-3.06). Risk factor analysis showed that only gender was significantly associated with carriage, where women were less likely to be carriers than men (relative risk 0.83, 95% CI 0.54-0.99). Serum 25OHD concentrations were not associated with the risk of carriage. In conclusion, monthly administration of 100 000 IU of vitamin D3 did not reduce persistent S. aureus nasal carriage.

The utility of plasma CRH as a predictor of preterm delivery.

It has been suggested that CRH is a placental clock that controls the duration of pregnancy and that the timing of the rise in CRH may permit prediction of the onset of labor. We have performed a prospective longitudinal study, in 297 women, to examine the utility of a single second-trimester plasma CRH measurement to predict preterm delivery. Venous blood samples were taken at 4-weekly intervals, beginning at 16-20 wk gestation, until delivery for CRH and its binding protein. A time point at which a single plasma CRH test might give optimal data to predict preterm delivery was determined. Thirty-one subjects delivered prematurely (10.4%). Sampling for plasma CRH at 26 wk gestation seemed the optimal time point to maximize sensitivity and specificity of the test. The mean (+/- SD) plasma CRH in women at this gestation who eventually delivered after spontaneous labor within 1 wk of their due date (39-41 wk, n = 127) was 34.7 +/- 27.0 pM. A plasma CRH of more than 90 pM at 26 wk gestation had a sensitivity of 45% and a specificity of 94% for prediction of preterm delivery. The positive predictive value was 46.7%. Calculation of free CRH did not improve these figures. In conclusion, a single measurement of plasma CRH, toward the end of the second trimester, may identify a group at risk for preterm delivery, but over 50% of such deliveries will be unpredicted. These data do not support the routine clinical use of plasma CRH as a predictor of preterm labor.

Cost-benefit analysis and prediction of 24-hour proteinuria from the spot urine protein-creatinine ratio.

AIM: A prospective cross-sectional study was performed on 170 patients with various glomerular diseases to study the accuracy of predicting 24-hour proteinuria from the spot urine protein-creatinine ratio (Up/Uc). A cost-benefit analysis was performed for the New Zealand health economic system to obtain the best cut-off values for proteinuria. SUBJECTS, METHODS AND RESULTS: Two spot urine samples (Up/Uc1 and Up/Uc2) were collected on the same day as the collection of a 24-hour urine. A randomly chosen subsample of 50 patients provided a second set of urine samples. The correlation and precision of agreement between the two methods were examined. The predictive intervals were calculated for derived 24-hour proteinuria. The level of agreement was evaluated by the Bland-Altman method and concordance analysis. The limits of agreement were evaluated against the clinical limits of agreement. A cost-benefit analysis (CBA) was performed to obtain the optimum operating points on receiver operating characteristic (ROC) curves for the best decision threshold. Correlations of r = 0.97 and 0.99 were observed between Up/Uc1, Up/Uc2 and 24-hour proteinuria, respectively. The 95% predictive intervals were wide. A high concordance correlation coefficient was obtained. The most of the differences between the two methods fell within the clinical limits of agreement. The Up/Uc1 of 0.26 and 3.20 represent the best thresholds to detect normal and nephrotic proteinuria, respectively. CONCLUSIONS: Despite wide confidence intervals, a good correlation and precision of agreement were demonstrated between the two methods across the whole range of proteinuria, regardless of the level of renal function. The difference between the two methods was less than the biological variability in the protein excretion and its measurement, enabling the methods to be used interchangeably. The optimum thresholds for abnormal and nephrotic range proteinuria were obtained.

Effect of anticoagulants and storage temperatures on stability of plasma and serum hormones.

OBJECTIVES: To determine the effect of different anticoagulants and storage conditions on the stability of hormones in plasma and serum. DESIGN AND METHODS: Human blood samples were collected from volunteers into EDTA, lithium heparin, sodium fluoride/potassium oxalate, or tubes without anticoagulant, plasma and serum left at -20 degrees C, 4 degrees C or 30 degrees C for 24 and 120 hours then assayed for ACTH, aldosterone, alpha-subunit, AVP, CRH, C-peptide, estradiol, FSH, glucagon, GH, IGF-1, IGFBP-3, insulin, leptin, LH, PPP, PTH, prolactin and VIP, or at room temperature for 0 to 72 hours (BNP, NT-BNP)(n = 6 per condition). RESULTS: The anticoagulant altered the measured concentrations for 9 hormones when compared to EDTA. All hormones except ACTH were stable for > 120 hours in EDTA or fluoride at 4 degrees C, but only 13 hormones were stable in all anticoagulants. At 30 degrees C, 8 hormones were stable for > 120 hours in EDTA, and 3 hormones in all anticoagulants. BNP and NT-BNP were stable for < 24 hours when stored in EDTA or heparin at room temperature. DISCUSSION: Storage of samples in EDTA plasma at 4 degrees C is suitable for most hormones (except ACTH) for up to 120 hours.

Interactions of CRH, AVP and cortisol in the secretion of ACTH from perifused equine anterior pituitary cells: "permissive" roles for cortisol and CRH.

To further elucidate the interaction of CRH, AVP and cortisol in the control of ACTH secretion, we used an in vitro perifusion model with dispersed equine anterior pituitary cells. To approximate the in vivo milieu in the horse, CRH was perifused continuously (at 0, 2 and 20 pmol/L) and 5-min pulses of AVP (0, 1, 3 and 10 nmol/L) were given every 30 min in the presence of 0 or 100 nmol/L cortisol. Total (baseline + incremental) ACTH secretion increased as both the CRH (p<0.001) and the AVP (p<0.001) concentration increased and interaction between CRH and AVP was significant (p=0.042). Cortisol reduced total ACTH secretion in the presence of 2 pmol CRH/L (p=0.001) but not 0 or 20 pmol CRH/L. For incremental ACTH there was interaction between CRH and AVP (p<0.0001), with increased secretion at higher concentrations, and no significant main effect of cortisol. There was significant (p=0.001) interaction between cortisol and CRH, with cortisol attenuating ACTH release at 0 pmol CRH/L (p=0.008), having no effect at 2 pmol CRH/L and potentiating it at 20 pmol CRH/L (p=0.026). We conclude that (1) CRH at high physiological levels has a "permissive" role in preventing the cortisol inhibition of the ACTH response to AVP, and (2) basal cortisol levels have a "permissive" action in priming the HPA axis for maximal responsiveness to stimulated levels of CRH and AVP.

Growth hormone binding protein correlates strongly with leptin and percentage body fat in GH-deficient adults, is increased by GH replacement but does not predict IGF-I response.

GH-binding protein (GHBP) corresponds to the extracellular domain of the GH receptor (GHR) and has been shown to be closely related to body fat. This study aimed to examine the inter-relationship between GHBP, leptin and body fat, and to test the hypothesis that GHBP is modified by GH replacement in GH-deficient adults and predicts IGF-I response. Twenty adults, mean age 47 years (range 20-69) with proven GH deficiency were randomly allocated to either GH (up to 0.25 U/kg/week in daily doses) or placebo for 3 months before cross-over to the opposite treatment. Plasma GHBP and leptin were measured at baseline and 2, 4, 8 and 12 weeks after each treatment. Whole body composition was measured at baseline by dual-energy X-ray absorptiometry (DEXA). There was a strong correlation between baseline leptin and GHBP (r = 0.88, P < 0.0001) and between baseline GHBP and percentage body fat, (r = 0.83, P < 0.0001). Mean GHBP levels were higher on GH compared with placebo, 1.53 +/- 0.28 vs 1.41 +/- 0.25nM, P = 0.049. There was no correlation between baseline IGF-I and GHBP (r = -0.049, P = 0.84), and GHBP did not predict IGF-I response to GH replacement. The close inter-relationship between GHBP, leptin and body fat suggests a possible role for GHBP in the regulation of body composition. GHBP is increased by GH replacement in GH-deficient adults, but does not predict biochemical response to GH replacement.

Peripheral plasma levels of beta-endorphin in alcoholics and highly trained athletes and the relationship to a measure of central opioid tone.

Human beta-endorphin-like immunoactivity was measured in highly trained athletes (n = 10), alcoholics in the early phase of abstinence (n=9) and normal controls (n=15) using the Nichols Allegro immunoradiometric assay. The assay was examined for cross reactivity against related peptides, beta-lipotropin and human N-acetyl beta-endorphin. Venous blood sampling was carried out in the morning at 0900 and 1100 hours in a fasting state. Using two-way analysis of variance there was a significant effect of subject group on beta-endorphin concentration (p=0.029). Post-hoc analysis using the Bonferroni t-test showed that the source of the difference was the alcoholic group having significantly lower beta-endorphin immunoreactivity (p < 0.05). There was no difference between the controls and the athletes. There was a positive correlation between plasma beta-endorphin level at 1100 hours and the subsequent ACTH incremental response to naloxone in the group as a whole (r=0.48, p=0.004). The assay showed 100% cross reactivity with beta-lipotropin and 73% cross reactivity with N-acetyl-beta-endorphin. We conclude that alcoholics have reduced levels of beta-endorphin-like immunoactivity. While beta-endorphin is known not to cross the blood-brain barrier, levels of plasma beta-endorphin-like immunoactivity may indirectly reflect central opioid activity.

The effect of recombinant follicle stimulating hormone (Gonal-F) on endogenous luteinizing hormone secretion in women.

Parenteral administration of follicle stimulating hormone (FSH) has been shown to lower luteinizing hormone (LH) concentrations in women undergoing ovulation induction. This study was designed to explore the physiological mechanism of this effect. Seven healthy women were recruited into a double-blind placebo-controlled study. LH secretion, after the administration of variable i.v. boluses (37.5, 75 and 150 IU) of recombinant FSH (Gonal-F), was evaluated. LH was measured at 10 min intervals for 2 h before and 4 h after the FSH/placebo infusion. LH pulse frequency and amplitude were evaluated and there was no significant difference between control and trial cycles for each subject. A linear regression analysis revealed that in the group receiving 150 IU FSH, the mean plasma LH concentration decreased significantly due to a reduction tonic LH secretion. This could be a result of the suppression of secretion or an alteration of clearance. This decrease was not seen in the other dosage groups, revealing that above a dosage threshold, FSH reduced non-pulsatile LH secretion. Therefore the effect of FSH in this study exposed the likely presence of two components of LH concentration: an FSH-sensitive, non-pulsatile tonic secretion and a gonadotrophin-releasing hormone-stimulated, pulsatile release that is unaffected by FSH. Although an indirect effect involving ovarian regulation is not excluded, the rapidity of the effect suggests that FSH acts directly on the pituitary gland.

Rapid assay of plasma brain natriuretic peptide in the assessment of acute dyspnoea.

AIM: Recognition of heart failure may be difficult in patients presenting with acute dyspnoea, particularly in the presence of chronic airways obstruction or obesity. In a previous study of patients with acute dyspnoea, we showed that the measurement of plasma brain natriuretic peptide (BNP)-a hormone secreted in increased amounts by the failing heart-accurately distinguishes heart failure from primary lung disorder. The aim of the present study was to develop a rapid assay for BNP and evaluate its diagnostic use in patients acutely hospitalised for increasing dyspnoea of any cause. METHODS: A rapid assay for plasma BNP, providing results within 24 h of blood collection, was developed without loss of precision. The results of the rapid and previously established BNP assays were highly correlated (r = 0.9). To determine the diagnostic value of the rapid assay, measurements were undertaken on the day of admission in 123 breathless patients (mean age 68.3, range 23 to 90 years) and related to conventional diagnostic assessments and final outcome. RESULTS: In patients diagnosed and treated urgently for clinical heart failure, plasma BNP was significantly higher (115 (SE 13) pmol/L, n = 39) than in those without clinical heart failure (33 (5) pmol/L, n = 84, p < 0.001). Using a cut-off of 50 pmol/L for the presence of heart failure, there was discordance between BNP level and clinical diagnosis in 21 of 123 cases. Reassessment after independent analysis of discordant cases increased the difference in BNP level in the presence (123 (13) pmol/L, n = 43) or absence (24 (1.5) pmol/L, n = 80) of heart failure. Using two way analysis of variance, no further improvement in discrimination was found when chest radiographs were used together with the BNP data. CONCLUSION: Rapid BNP assays are practicable and provide accurate information on cardiac status-superior to chest radiographs in many cases-early in the course of the patient's presentation with acute dyspnoea.

Atrial natriuretic peptide and C-type natriuretic peptide do not acutely inhibit the release of adrenocorticotropin from equine pituitary cells in vitro.

It has been suggested that atrial natriuretic peptide (ANP) is the long-sought inhibitor of corticotropin (ACTH) secretion, but the evidence is conflicting. We have examined the effect of ANP and C-type natriuretic peptide (CNP) on the secretion of ACTH by perifused equine pituitary cells in an in vitro milieu intended to mimic the in vivo milieu in the horse. Corticotropin-releasing hormone (20 pM) and cortisol (0 or 100 nM) were perifused continuously and 7 pulses of arginine vasopressin (AVP; 10 nM) applied for 5 min at 30-min intervals. ANP (1 nM) or CNP (1 nM) were perifused continuously for 75 min, beginning before the 3rd AVP pulse. Neither ANP nor CNP, with or without cortisol, significantly altered the ACTH secretory response to the AVP pulses. We conclude that these natriuretic peptides are unlikely to act at the pituitary as rapid inhibitors of ACTH secretion in the horse.

Low-dose growth hormone replacement lowers plasma leptin and fat stores without affecting body mass index in adults with growth hormone deficiency.

OBJECTIVE: The ob gene product, leptin, is considered to be a marker of adipose tissue mass and a possible homeostatic regulator of body mass. Our objective was to examine the effect of GH replacement on adipose tissue stores and leptin in adult hypopituitarism. SUBJECTS: Twenty adults, mean age 47 years (range 20-69) with proven GH deficiency were randomly allocated to either GH (up to 0.25 U/kg/week in daily doses) or placebo for 3 months before cross-over to the opposite treatment. MEASUREMENTS: Body composition was measured by dual-energy X-ray absorptiometry (DEXA) in the whole body, trunk and limbs. Plasma leptin was measured by radioimmunoassay at baseline and +2, +4, +8 and +12 weeks in each treatment arm. RESULTS: Total body tissue fat (mean +/- SE) was 30.1 +/- 2.2% after GH compared with 31.9 +/- 2.2% after placebo, P < 0.001 (ANOVA). There were no significant changes in BMI (kg/m2), 29.1 +/- 1.3 after placebo vs 28.8 +/- 1.2 after GH; or waist to hip ratio (WHR), 0.91 +/- 0.01 after both placebo and GH. Baseline plasma leptin showed a significant correlation with baseline BMI, r = 0.67, P < 0.005 and baseline percentage total body fat, R = 0.89, P < 0.001. Plasma leptin (adjusted by using baseline percentage total body fat as a covariate) showed a significant linear decrease with time on GH compared with placebo (P = 0.03, ANOVA). CONCLUSIONS: Plasma leptin and total body fat fall promptly in response to low-dose replacement of GH in GH-deficient subjects. Hormone-induced changes in leptin can occur in humans in the absence of change in body mass index.

Adaptation of the hypothalamopituitary adrenal axis to chronic exercise stress in humans.

Repeated acute or chronic exposure to a particular stress results in adaptation whereby the hypothalamopituitary adrenal (HPS) axis becomes less responsive to subsequent or continued exposure to that particular stress. To investigate the adaptive changes that occur in the HPA axis in response to chronic stress in humans, we studied the effect of chronic exercise stress on basal activity of the HPA axis in six highly trained male ultramarathon athletes and six healthy male controls matched for body mass index. After 3-5 of abstention from intense physical activity, the subjects were admitted to a metabolic study ward at 1600 h. Peripheral blood was sampled initially at 0300 h, at 20-min intervals from 0400 to 0900 h, hourly from 0900 to 1200 h, and then every 2 h from 1200 to 1600 h. A 24-h urine collection was completed during the admission. Peripheral blood adrenocorticotropic hormone (ACTH) was measured by radioimmunoassay. Plasma and urinary cortisol were measured by enzyme-linked immunoassay. Plasma and injury cortisol were measured by enzyme-linked immunosorbent assay (ELISA). Plasma ACTH and cortisol levels showed the expected diurnal change in athletes and control subjects (P = 0.00001). However, the early morning ACTH and cortisol surge occurred earlier in the athletes than in the controls (P = 0.026). Plasma ACTH levels were significantly higher in the athletes than in the control subjects (P = 0.0026). There was, however, no significant overall difference in plasma cortisol levels between the athletes and the control subjects, and urinary excretion of free cortisol was similar in the two groups. These data show that intense physical training leads to adaptive changes in basal HPA function, including a phase shift and increased pituitary in basal HPA function, including a phase shift and increased pituitary ACTH secretion, but also blunting of the adrenal cortisol response.

The integrative control of adrenocorticotrophin secretion: a critical role for corticotrophin-releasing hormone.

Perifused equine anterior pituitary cells were used to investigate the relationships between the secretion of ACTH and substances known to either stimulate (corticotrophin-releasing hormone (CRH), and arginine vasopressin (AVP)) or inhibit (cortisol) ACTH secretion. The experiments were designed to mimic the hormone milieu present in vivo in the horse, with cortisol (0 or 100 nmol/l) and CRH (0 or 0.02 nmol/l) perifused continuously, and pulses of AVP (10 nmol/l) applied for 5 min at 30-min intervals. In columns perifused with 0.02 nmol CRH/l there was no significant overall effect of 100 nmol cortisol/l on the ACTH responses to pulses of AVP, although there was a significant interaction between AVP pulse number and cortisol showing that ACTH total area (pmol ACTH proportional to area under response curve) in response to AVP pulses 1 and 2 was significantly (P < 0.05) decreased in columns perifused with 100 nmol cortisol/l. However ACTH incremental area (pmol ACTH proportional to the area above the CRH-induced baseline) was not affected by cortisol at any AVP pulse. This contrasts with the effect of cortisol in columns perifused with 0 nmol CRH/l, where 100 nmol cortisol/l significantly decreased ACTH total area (P = 0.0075) and incremental area (P = 0.049) at all AVP pulses compared with the responses in columns receiving 0 nmol cortisol/l. There was a fall off in ACTH responsiveness with time during the experiment which, in the presence of 0.02 nmol CRH/l, was significantly (P < 0.001) greater with 0 nmol cortisol/l than with 100 nmol cortisol/l and if 6 (rather than 3) pulses of AVP were given, whereas with 0 nmol CRH/l there was no difference in the fall off with time between columns receiving 0 and 100 nmol cortisol/l. These results show that the control of ACTH secretion is influenced not only by independent action of secretagogues such as CRH and AVP, or inhibitors such as cortisol, but by a complex interaction of these factors with one another. CRH may have a role in 'protecting' the ACTH response to pulses of AVP in the presence of cortisol. It follows that, in vivo, 'background' CRH could allow an increase in ACTH in response to AVP released by a new stress, despite the presence of elevated cortisol.

The effect of beta-endorphin on basal and insulin-hypoglycaemia stimulated levels of hypothalamic-pituitary-adrenal axis hormones in normal human subjects.

OBJECTIVE: It has been demonstrated that beta-endorphin reduces CRH production and hypoglycaemia-induced ACTH secretion in the rat. We aimed to determine whether supraphysiological levels of beta-endorphin inhibit the ACTH and CRH response to insulin-induced hypoglycaemia in human subjects. DESIGN: Plasma glucose, prolactin, cortisol, ACTH, CRH and AVP were measured at intervals over a 3-hour period. Intravenous beta-endorphin 5 mg/50 ml or an equal volume of normal saline was infused between 30 and 90 minutes, with soluble insulin 0.15 units/kg administered i.v. at 60 minutes in a cross-over design. SUBJECTS: Six healthy male volunteers aged 20-35 years. MEASUREMENTS: Prolactin was measured by a fluoroimmunometric assay, ACTH, CRH and AVP by radioimmunoassay, and cortisol was measured by enzyme-linked immunosorbent assay. Haemodynamic measurements were recorded prior to each blood sample. Results are expressed as mean +/- standard error of the mean. RESULTS: beta-Endorphin resulted in a significant decrease in baseline cortisol (P < 0.05) but not ACTH. Plasma glucose (P < 0.001) and CRH (P < 0.05) and PRL (P < 0.05) increased significantly during beta-endorphin compared to normal saline. After insulin administration, glucose reached a similar nadir during beta-endorphin and normal saline (2.1 +/- 0.1 and 1.9 +/- 0.15 mmol/l, respectively) but the fall in plasma glucose was delayed during beta-endorphin (P < 0.01 by ANOVA). This resulted in a significantly altered time-course for the ACTH and cortisol responses (P < 0.05 for each), but no difference overall in the magnitude of the response. In contrast, neither the timing nor the magnitude of the CRH and AVP responses were affected. Prolactin also reached a similar peak value after the administration of insulin, while the haemodynamic responses to hypoglycaemia were not significantly altered during beta-endorphin. CONCLUSIONS: While beta-endorphin has been shown to be inhibitory to basal ACTH and cortisol secretion in humans, we note a significant increase in plasma CRH in response to beta-endorphin, which may be arising from a peripheral source. Intravenous beta-endorphin increases plasma glucose and delays the onset of hypoglycaemia following insulin but does not result in significant inhibition of the ACTH and cortisol response. This may reflect the poor penetration of beta-endorphin into the central nervous system, although a hypothalamic effect of beta-endorphin is implied by the increased PRL. The significantly delayed time course in ACTH and cortisol secretion noted during beta-endorphin is not explained by a later response of either CRH or AVP. Although peripheral levels of these hormones may be a relatively insensitive measure of hypothalamic function, an additional factor may influence ACTH release during hypoglycaemia.

The effects of alcoholism on the hypothalamic-pituitary-adrenal axis: interaction with endogenous opioid peptides.

BACKGROUND: Abnormal baseline hypothalamic-pituitary-adrenal axis function and dexamethasone suppressibility seen in withdrawing alcoholics returns to normal on abstinence, but some studies report blunting of the ACTH response to CRH persisting during the early abstinence phase. Reduced central levels of endogenous opioid peptides have been postulated to have an aetiological role in alcohol addiction. AIMS: To evaluate hypothalamic-pituitary-adrenal axis function in a group of recently abstinent alcoholics using basal hormone data, naloxone (an opioid receptor antagonist), and ovine CRH. SUBJECTS: Nine alcoholics (age 41.4 +/- 3.1 years) studied more than one week after the acute withdrawal period but within 6 weeks of cessation of drinking, and nine age and sex matched non-alcoholic controls. PROTOCOL: Cortisol, ACTH, CRH and AVP levels were measured every 20 minutes for 2 hours between 0900 and 1100h Twenty mg naloxone i.v. was administered at 1100h (0 minutes) and further samples for the above hormones were taken at 15, 30, 45, 60, 90 and 120 minutes. On a separate occasion, again at 1100h, oCRH 1 microgram/kg (n = 7 alcoholics, n = 6 controls) was administered, with samples for cortisol, ACTH and AVP taken at the same times. STATISTICS: Results were examined by analysis of variance for repeated measures (ANOVA), while incremental hormone response and area under the secretory curve (AUC) in alcoholics versus controls were compared by the two-tailed Student's t-test. Linear regression analysis was carried out to examine the relation between basal cortisol and hormone responses to naloxone and oCRH. RESULTS: Basal hormone levels did not differ between the groups. The alcoholics had a blunted ACTH incremental response to naloxone (11.4 +/- 3.0 vs 21.1 +/- 2.5 pmol/l, P < 0.05) but the cortisol response was not significantly different (205 +/- 51 vs 305 +/- 42 nmol/l, P = 0.15). The alcoholics also had a blunted ACTH incremental response to oCRH (28.7 +/- 4.2 vs 41.2 +/- 3.7 pmol/l, P = 0.052) and by ANOVA a significant main effect of group (alcoholic vs control) was seen (P < 0.02) for the ACTH response to oCRH. There was no difference between the groups in the cortisol incremental response to oCRH. In the control subjects, a negative correlation was found between basal cortisol and the cortisol increment (r = -0.82, P < 0.05) and ACTH increment (r = -0.81, P = 0.052) following oCRH, while in contrast, basal cortisol correlated positively with cortisol increment (r = 0.72, P < 0.05) following naloxone. There was also a trend for basal cortisol to correlate positively with ACTH increment following naloxone in the controls (r = 0.63, P < 0.07). In the alcoholics, the normal negative effect of basal cortisol on the cortisol increment after oCRH was reversed, with a positive correlation between basal cortisol and cortisol increment (r = 0.75, P = 0.05). CONCLUSIONS: Recently abstinent alcoholics with normal basal HPA axis hormone levels have a blunted ACTH response to naloxone and oCRH. While reduced levels of central endogenous opioid peptides may be a factor in the blunted ACTH response to naloxone in the alcoholics, it is proposed that the alcoholics have reduced pituitary responsiveness to CRH. This may be via a direct pituitary effect of the chronic ethanol exposure or by a reduction in hypothalamic-hypophyseal vasopressin levels.

Distribution of positive moods in women with the premenstrual syndrome and in normal women.

A daily mood record was kept by 44 women presenting with PMS (PMS+ group: 133 menstrual cycles) and by 48 normal women (PMS- group: 100 cycles). Peaks of maximum positive mood were located after fitting either a 5-term or a 3-term Fourier series to the data. In the PMS+ group mood peaks were clustered to a significant degree (p < 0.001) around day 11 in a 28-day menstrual cycle (95% confidence interval: days 10-12); this is the time of the pre-ovulatory oestrogen surge. In the PMS- group clustering was insignificant. Menstrual cycle parameters were similar in the two groups (PMS+ vs. PMS-: mean duration cycle, 27.6 +/- 3.2(SD) vs. 26.7 +/- 2.5 days; incidence ovulatory cycles, 95.5 vs. 93.0%). The evidence suggests either that the ovarian hormone cycle has no effect on mood, or that it has an effect only in women with PMS.

Elevated basal adrenocorticotropin and evidence for increased central opioid tone in highly trained male athletes.

Basal cortisol and ACTH levels have previously been shown to be elevated in highly trained athletes, whereas the ACTH response to ovine CRH has been reported to be diminished compared to that in nonathletic controls. Naloxone, a nonselective opioid receptor antagonist, is known to stimulate ACTH and cortisol secretion. The mechanism of this response is thought to be via increased hypothalamic CRH secretion. The aim of this study was to examine basal and naloxone-stimulated levels of hypothalamic-pituitary-adrenal axis hormones in male athletes. Ten highly trained male athletes and 10 nonathletic controls took part in the study. Peripheral venous blood was sampled for cortisol, ACTH, CRH, and arginine vasopressin (AVP) for 2 h before the administration of 20 mg naloxone, i.v., and 15, 30, 45, 60, 90, and 120 min after naloxone treatment. Body mass index was significantly lower in the athletes (P < 0.001). Basal (prenaloxone) ACTH levels were higher in the athletes (P < 0.05), whereas levels of cortisol, CRH, and AVP were similar in both groups. After naloxone treatment, there was a significantly greater rise in ACTH in the athletes (P < 0.02). There was also a trend for the cortisol response to be greater, which was not statistically significant (P < 0.07). Although in both groups, peripheral CRH rose after naloxone treatment (P < 0.005), a rise of similar magnitude occurred over the 2-h period before naloxone (P < 0.0001). Plasma AVP did not change significantly after naloxone treatment. Neither the plasma cortisol level at baseline nor the body mass index correlated significantly with the ACTH or cortisol response to naloxone. The presence of an enhanced ACTH response to naloxone is evidence that central opioid tone may be increased in highly trained athletes. However, there is no associated suppression of the hypothalamic-pituitary-adrenal axis, and basal ACTH levels are raised, without any detectable change in peripheral plasma CRH or AVP. An additional factor (other than CRH) that stimulates ACTH secretion may be released after naloxone administration.

Horse plasma corticotrophin-releasing hormone (CRH): characterisation and lack of a late gestational rise or a plasma CRH-binding protein.

Immunoreactive corticotrophin-releasing hormone (irCRH) was present in methanolic extracts of equine peripheral blood and showed no elevation in maternal peripheral serum in late gestation (0.54 +/- 0.25 pmol/l; mean +/- S.D.) compared with control horses (0.41 +/- 0.15 pmol/l). The irCRH of methanolic extracts of pituitary venous plasma had a similar elution position following reverse-phase HPLC to synthetic human CRH(1-41) and to irCRH released from horse stalk-median eminence tissue incubated in vitro. Gel chromatographic studies showed no evidence for a plasma CRH-binding protein (CRHBP) analogous to that found in human plasma in either peripheral blood from normal or pregnant horses or in pituitary venous plasma sampled from a cannulated horse. CRH-binding activity was detectable in peripheral plasma from one horse, however the molecular size of this was indicative of a gamma-globulin rather than the 37 kDa CRHBP. These studies suggest that, unlike in the human, CRH does not rise to high values in late gestation nor circulate in a bound form in equine plasma.