Effect of androstenedione administration on the maternal hypothalamo-pituitary-adreno-placental axis in the pregnant rhesus monkey

To assess the interaction among androgens, placenta, and the hypothalamo-pituitary-adrenal axis we studied effects of androstenedione administered intravascularly to the pregnant monkey on maternal plasma CRH, ACTH, dehydroepiandrosterone sulfate (DHEAS), cortisol, and estradiol concentrations. Ten monkeys (128 +/- 3 days gestation; mean +/- SEM) were instrumented under general halothane anesthesia with maternal femoral artery and venous catheters and uterine electromyogram electrodes. At 137-144 days gestation, baseline maternal femoral artery samples for CRH, ACTH, DHEAS, cortisol, and estradiol measurements were taken at 1.5-h intervals for 7 h starting 2 h before darkness. On the following day, a continuous iv androstenedione infusion (0.3 mg/kg.min at 0.25 ml/h) in 10% intralipid was started at 0930 h in four monkeys; the other six animals received vehicle alone at the same rate starting at the same time. Maternal blood sampling was repeated 1 and 3 days after androstenedione or vehicle administration. Maternal plasma CRH, ACTH, DHEAS, cortisol, and estradiol levels were unaffected by intralipid. In contrast, androstenedione infusion produced a sustained increase in maternal plasma estradiol and a sustained fall in maternal plasma ACTH, but did not affect maternal plasma CRH, DHEAS, or cortisol concentrations. These results provide evidence for negative feedback regulation by androgens at the hypothalamo-pituitary-adrenal axis in the pregnant monkey. Lack of inhibition of maternal plasma CRH after androstenedione administration supports differential regulation of hypothalamic and placental CRH by androgens.     

Update on the biologic effects of macrophage colony-stimulating factor

OBJECTIVE: The aims of this investigation were to measure corticotropin-releasing hormone (CRH), corticotropin (ACTH) and cortisol before, during and after delivery searching for an endocrine intercorrelation of the hypothalamic-pituitary-adrenal (HPA) axis and to correlate these findings with obstetrical variables. METHODS: Blood was sampled from 50 women with singleton pregnancies at term without uterine contractions, during delivery (after full cervical dilatation) and on the 4th postnatal day. Hormones were measured by radioimmunoassay (RIA). The correlation between obstetric variables, sociodemographic and endocrine data were evaluated using the Spearman rank coefficient. Group comparisons for continuous variables were calculated using the Mann-Whitney U test and Kruskal-Wallis test. RESULTS: Maternal plasma ACTH and cortisol increased significantly during labor, declining toward the 4th postnatal day (p < 0.001) and showing a significant intercorrelation (p < 0.01). Compared to women without uterine contractions CRH rose during labor (p < 0.05) and decreased rapidly to the 4th postnatal day (p < 0.001). No correlations between CRH and ACTH or cortisol were observed. None of the obstetrical variables (parity, newborn's weight, duration of delivery) revealed any significant correlation with ACTH. Analgetic medication (pethidine hydrochloride) was not able to influence the endocrine response to labor stress. CONCLUSIONS: Stressful experience during childbirth has an impact on endocrine response. However, this is not fully evident along the HPA axis in a simple biological model with monocausal dependencies. This 'biological stress model' is not sensitive enough to detect different childbirth conditions and the hormones in the maternal compartment have partially fetal (placental) origin.     

Hypothalamic-pituitary-adrenal function one week after a short burst of steroid therapy

"Steroid burst therapy" is commonly used for various acute medical conditions, but its suppressive effect on hypothalamic-pituitary-adrenocortical (HPA) function and the time period for recovery of HPA function is not fully known. We therefore evaluated the HPA function in 10 normal adults before and after a short burst of Prednisone (40 mg/three times daily for 3 days, then tapered over the next 4 days). HPA function was evaluated by iv administration of 100 micrograms of ovine CRH (oCRH) and blood samples for ACTH and cortisol assay were obtained at -30,0,10,15,30,60,90, and 120 min. On another day, 250 micrograms synthetic ACTH (Cosyntropin) were given iv and blood samples for cortisol were obtained at 0,30,60, and 90 min. Basal and peak levels of ACTH and cortisol before and 1,2, and 3 weeks after discontinuation of prednisone in response to oCRH iv are shown below (see Table 1). All values are mean (SEM). Peak levels of cortisol after iv administration of Cosyntropin at week 0 were 922(56.8), week 1 899(63.7), week 2 861(70.9), and week 3 855(53.0). There was no significant difference noted in the levels of ACTH and cortisol in response to oCRH before and after prednisone treatment. Pre- and posttreatment responses of cortisol to Cosyntropin administration were also similar. In addition, cumulative responses (area under the curve) and the change from baseline (delta) before and after administration of prednisone were similar for ACTH and cortisol. We conclude that HPA function is normal 1 week after discontinuation of a short burst of prednisone. These findings suggest that administration of additional steroids may not be required during periods of "stress" for those patients who have previously received similar steroid burst therapy, if at least 1 week has elapsed after such treatment was given.     

The frequency of late-onset 21-hydroxylase and 11 beta-hydroxylase deficiency in women with polycystic ovary syndrome

OBJECTIVE: To determine the frequency of late-onset adrenal hyperplasia (LOCAH) due to 21-hydroxylase (21-OH) and 11 beta-hydroxylase (11 beta-OH) deficiency in women with clinical and biochemical features of polycystic ovary syndrome (PCOS). DESIGN: Eighty-three consecutively selected women with PCOS and eighteen normal women were included in the study. METHODS: Ultrasound, clinical and hormonal parameters were used to define PCOS. Basal FSH, LH, testosterone, free testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEA-S), sex hormone-binding globulin (SHBG) and cortisol levels were measured. Serum 17-hydroxyprogesterone (17-OHP) and 11-deoxycortisol (11-DOC) levels were also measured before, 30 and 60 min after a single bolus injection of 0.25 mg ACTH (1-24) at 0900 h during the mid-follicular phase of the cycle. ACTH-stimulated 17-OHP levels > 30 nmol/l were considered as the criteria of 21-OH deficiency. The diagnosis 11 beta-OH deficiency was made if the adrenal 11-DOC response to ACTH stimulation exceeded threefold the 95th percentile of controls. RESULTS: Basal serum testosterone, free testosterone, androstenedione, DHEA-S, cortisol and 11-DOC levels were significantly higher in PCOS than in control subjects. ACTH-stimulated 17-OHP (P < 0.05) and 11-DOC (P < 0.0005) levels were found to be significantly higher in patients with PCOS than in controls. Seven (8.4%) patients had an 11-DOC response to ACTH higher than threefold the 95th percentile of controls, while no patients showed evidence of 21-OH deficiency. CONCLUSIONS: We have found that 8.4% of the women with clinical and biochemical features of PCOS could be presumed to have 11 beta-OH deficiency. No patients among the women with PCOS showed evidence of 21-OH deficiency. 11 beta-OH deficiency is unexpectedly more common than 21-OH deficiency in women with PCOS.     

Differences in corticotropin-releasing hormone-stimulated adrenocorticotropin and cortisol before and after weight loss

Little is known about the effects of intentional weight loss on the function of the hypothalamic-pituitary-adrenal (HPA) axis of obese individuals. We studied the HPA axis of 34 healthy obese women (body mass index, 40.2 +/- 7.9 kg/m2) before and after a 21.0 +/- 7.9-kg weight loss induced by a 26-week weight loss program that included 12 weeks of a 3350 kJ/day (800 Cal/day) liquid formula diet, 6 weeks of gradual refeeding, and 6 weeks of caloric stabilization at 5020-6280 kJ/day (1200-1500 Cal/day). Obese subjects were evaluated twice: before caloric restriction and during the last 3 weeks of caloric stabilization with a 3-h evening 1 microg/kg ovine CRH (oCRH) stimulation test. CRH-stimulated ACTH and cortisol values were compared to those of a control group of 12 normal weight women. Before caloric restriction, both ACTH and cortisol responses to oCRH were similar in obese women and normal weight controls. Weight loss did not significantly alter the ACTH response to oCRH; however, the total plasma cortisol response to oCRH decreased significantly with weight loss (area under the curve, 96,320 +/- 21,040 nmol/L x min before weight loss; 82,450 +/- 22,460 nmol/L x min after weight loss; P < 0.001). Cortisol-binding globulin also decreased significantly after weight loss (2,270 +/- 1,050 nmol/L) compared either to values obtained before weight loss (3,590 +/- 1,360 nmol/L; P < 0.001) or to those of normal weight controls (3,910 +/- 1,400 nmol/L; P < 0.001). Assay for plasma free cortisol, either before or 180 min after oCRH treatment, showed no significant changes in cortisol responses resulting from weight loss. As plasma free cortisol was not altered by weight reduction, the decrease in the total cortisol response to oCRH after weight loss appears to be secondary to significant decreases in cortisol-binding globulin. We conclude that when obese women lose large amounts of weight with a 3350 kJ/day, very low energy diet, such weight reduction does not significantly affect the HPA axis.     

Tetanus toxoid stimulation of the hypothalamic-pituitary-adrenal axis correlates inversely with the increase in tetanus toxoid antibody titers

In humans, endotoxin activates the hypothalamic-pituitary-adrenal (HPA) axis, and the resulting increase in cortisol modulates the immune response. There is little information on the HPA axis response to other antigens. We examined the effect of the protein antigen tetanus toxoid on HPA axis activity in 10 healthy, premenopausal women (aged 28.6 +/- 2.6 yr). Subjects received im injections of placebo and tetanus toxoid at 1600 h on consecutive days. Blood samples for ACTH and cortisol were obtained every half-hour from--1 to 6 h and at 8, 12, and 16 h after each injection. Compared to placebo, tetanus toxoid administration stimulated significant increases in plasma ACTH and serum cortisol, with the maximum cortisol increase of 1.6-fold occurring 4.5 h after drug administration. Urinary free cortisol increased 1.8-fold in the 8 h after tetanus toxoid administration compared to that after placebo administration. Additionally, there was a significant inverse correlation (r = 0.87; P < 0.005) between the tetanus toxoid-induced increase in serum cortisol and the increase in tetanus antibody levels measured 1 month postvaccination. Thus, administration of the protein antigen tetanus toxoid activated the HPA axis in healthy, premenopausal women. This activation of the HPA axis correlated inversely with the antibody response to tetanus toxoid.     

Neurohormonal perturbations in fibromyalgia

Fibromyalgia (FM) falls into the spectrum of what might be termed 'stress-associated syndromes' by virtue of frequent onset after acute or chronic stressors and apparent exacerbation of symptoms during periods of physical or emotional stress. Patients with FM exhibit disturbances of the major stress-response systems, the HPA axis and the sympathetic nervous system. Integrated basal cortisol levels measured by 24-hour urine-free cortisol are low. FM patients display a unique pattern of HPA axis perturbation characterized by exaggerated ACTH response to exogenous CRH or to endogenous activators of CRH such as insulin-induced hypoglycaemia. The cortisol response to increased ACTH in these stress paradigms is blunted, as is the the cortisol response to exercise. Functional analysis suggests that FM patients may also exhibit disturbed autonomic system activity. For example, plasma NPY, a peptide co-localized with norepinephrine in the sympathetic nervous system, is low in patients with FM. Abnormalities of related neuronal systems, particularly decreased serotonergic activity, may contribute to the observed neuroendocrine perturbations in FM. Finally, other neuroendocrine systems, including the growth hormone axis, are also abnormal in FM patients. Many clinical features of FM and related disorders, such as widespread pain and fatigue, could be related to the observed neuroendocrine perturbations. This hypothesis is supported by the observation that many useful treatments for FM affect the function of these central nervous system centres. Further clarification of the role of neuroendocrine abnormalities in patients with FM, and the relationship of these disturbances with particular symptoms, may lead to improved therapeutic strategies.     

Function of the hypothalamic-pituitary-adrenal axis in patients with fibromyalgia and low back pain

OBJECTIVE: We suggested fibromyalgia (FM) is a disorder associated with an altered functioning of the stress-response system. This was concluded from hyperreactive pituitary adrenocorticotropic hormone (ACTH) release in response to corticotropin-releasing hormone (CRH) and to insulin induced hypoglycemia in patients with FM. In this study, we tested the validity and specificity of this observation compared to another painful condition, low back pain. METHODS: We recruited 40 patients with primary FM (F:M 36:4), 28 patients (25:3) with chronic noninflammatory low back pain (LBP), and 14 (12:2) healthy, sedentary controls. A standard 100 microg CRH challenge test was performed with measurement of ACTH and cortisol levels at 9 time points. They were also subjected to an overnight dexamethasone suppression test, followed by injection of synthetic ACTH1-24. At 9 AM, the patients divided in 2 groups, received either 0.025 or 0.100 microg ACTH/kg body weight to test for adrenocortical sensitivity. Basal adrenocortical function was assessed mainly by measurement of 24 h urinary excretion of free cortisol. RESULTS: Compared to the controls, the patients with FM displayed a hyperreactive ACTH release in response to CRH challenge (ANOVA interaction effect p = 0.001). The mean ACTH response of the patients with low back pain appeared enhanced also, but to a significantly lesser extent (p = 0.02 at maximum level) than observed in the patients with FM. The cortisol response was the same in the 3 groups. Following dexamethasone intake there were 2 and 4 nonsuppressors in the FM and LBP groups, respectively. The very low and low dose of exogenous ACTH1-24 evoked a dose and time dependent cortisol response, which, however, was not significantly different between the 3 groups. The 24 h urinary free cortisol levels were significantly lower (p = 0.02) than controls in both patient groups; patients with FM also displayed significantly lower (p < 0.05) basal total plasma cortisol than controls. CONCLUSION: The present data validate and substantiate our preliminary evidence for a dysregulation of the HPA axis in patients with FM, marked by mild hypocortisolemia, hyperreactivity of pituitary ACTH release to CRH, and glucocorticoid feedback resistance. Patients with LBP also display hypocortisolemia, but only a tendency toward the disrupted HPA features observed in the patients with FM. We propose that a reduced containment of the stress-response system by corticosteroid hormones is associated with the symptoms of FM.     

Blunted cortisol response after administration of corticotropin releasing hormone in endotoxemic dogs

To evaluate the effects of a standard inflammatory challenge on the dynamics of the hypothalamic-pituitary-adrenal (HPA) axis, we studied the effects of low-dose endotoxin (1.0 microgram/kg) on plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations in a saline-controlled study in five awake dogs. Four hours after endotoxin or saline challenge human corticotrophin-releasing hormone (hCRH; 1.0 microgram/kg) was administered. Plasma ACTH and cortisol levels increased considerably in response to endotoxin, from 13 +/- 1 ng/l to 360 +/- 85 ng/l (p < 0.01) and from 60 +/- 20 nmol/l to 710 +/- 80 nmol/l (p < 0.01). Despite a considerable difference in ACTH and cortisol levels prior to CRH administration between both studies (p < 0.01), the absolute increase in ACTH levels induced by hCRH was not different (231 +/ 43 ng/l vs 238 +/- 45 ng/l, control vs endotoxin). Plasma cortisol levels increased significantly in the control study (from 40 +/- 10 nmol/l to 330 +/- 40 nmol/l, p < 0.01), whereas they did not change in the endotoxin study after hCRH administration (from 710 +/- 80 nmol/l to 730 +/- 70 nmol/l, ns). We conclude that the HPA-axis reacts initially to endotoxin in such a way that cortisol, but not ACTH, secretion is maximized. Therefore, a blunted cortisol response to CRH testing is part of the initial response to infection.     

Sex differences in endocrine and psychological responses to psychosocial stress in healthy elderly subjects and the impact of a 2-week dehydroepiandrosterone treatment

Evidence from animal as well as human studies has suggested that significant sex differences exist in hypothalamus-pituitary-adrenal axis (HPA) activity. As gonadal steroids could be important modulators of HPA sex differences, stress responses were investigated in subjects of advanced age after dehydroepiandrosterone (DHEA) or placebo treatment. After a 2-week treatment with 50 mg DHEA daily or placebo, 75 men and women (mean age, 67.6 yr) were exposed to the Trier Social Stress Test (TSST). The TSST is a brief psychosocial stress that consists of a free speech and mental arithmetic task in front of an audience. The results show that the TSST induced significant increases in ACTH, salivary free cortisol, total plasma cortisol, norepinephrine, and heart rates (all P < 0.0001) as well as decreased positive affect in the elderly (P = 0.0009). Men showed larger stress responses in ACTH (P = 0.004), salivary free cortisol (P = 0.044), and plasma total cortisol (P = 0.076) compared to women. No sex differences were observed in norepinephrine, epinephrine, or heart rate responses. In contrast to ACTH and cortisol response differences, women reported that they were significantly more stressed by the TSST than men (P = 0.0051). Women treated with DHEA showed ACTH stress responses similar to those of men, but significantly enhanced compared to those of women taking placebos (P < 0.009). No other stress response differences emerged between DHEA and placebo groups. Finally, DHEA treatment did not result in an improvement of subjective well-being. We conclude that elderly men show larger HPA responses than women to psychosocial stress, as studied in the TSST. Estrogen effects on hypothalamic CRF-producing neurons might be responsible for these sex differences.     

Effect of immunomodulators pyrimethamine and cimetidine on immunosuppression induced by sulfur mustard in mice

A corticotropin-releasing hormone (CRH) stimulation test with four cumulative doses of human CRH (0.01, 0.06, 0.2 and 1 microgram/kg body weight) and infusion of a low dose of [Arg8]-vasopressin (0.004 U/kg body weight/30 min) was performed in five depressed patients and six healthy subjects. Plasma samples for the measurement of cortisol, ACTH and beta-endorphin were taken at regular intervals and considered as measures of pituitary-adrenal function. A dose-response relationship between CRH and the hormones measured was found in patients and controls. Depressed patients already responded to the lowest dose of CRH with respect to cortisol release, whereas ACTH and beta-endorphin responded to the second and third doses, respectively. In control subjects the cortisol and ACTH response started after the third dose of CRH, whereas beta-endorphin responded significantly to the highest dose only. When both groups were compared, differences in response were found to the higher doses of CRH with respect to cortisol, ACTH and, less markedly, beta-endorphin and to the lowest dose of CRH with respect to cortisol. Although numbers are small, the data show 'blunting' of the ACTH response to the higher doses of CRH in patients with an enhanced cortisol response of the adrenals to lower and higher doses of CRH. There was no significant difference in response when CRH was used with vasopressin as compared to treatment with CRH alone. Thus, in this design vasopressin did not contribute significantly to CRH activity. The data suggest that pituitary cell sensitivity might be changed in depression as part of HPA dysfunction.     

Evaluation of the integrity of the hypothalamic-pituitary-adrenal axis by insulin hypoglycemia test

We retrospectively reviewed dynamic ACTH and cortisol responses to insulin hypoglycemia in 193 subjects with suspected ACTH deficiency to ascertain the predictive values of various diagnostic criteria. Based on the achievement of a peak cortisol level of 18 micrograms/dL or above, 133 subjects were classified as having an intact hypothalamic-pituitary-adrenal (HPA) axis, and 60 subjects were determined to have ACTH deficiency. Baseline and peak cortisol concentrations were strongly correlated (r = 0.63; P < 0.0001). Peak cortisol increased in parallel to ACTH increments, but plateaued at approximately 22 micrograms/dL at peak ACTH levels above approximately 75 pg/mL (r = 0.61; P < 0.0001). Basal cortisol values above 17 micrograms/dL or below 4 micrograms/dL were highly predictive of an intact or impaired HPA axis, respectively, but intermediate values had only limited sensitivity and specificity. The criteria of HPA axis integrity, defined as an increment in plasma cortisol of more than 7 micrograms/dL above the baseline or as a doubling of the baseline cortisol value, were associated with high false positive and false negative rates. We conclude that 1) the baseline morning serum cortisol concentration has very limited predictive power in differentiating between normal and impaired HPA function; 2) the use of criteria based on incremental changes in serum cortisol from baseline leads to unacceptably high false positive and false negative rates; and 3) insulin hypoglycemia is still the best indicator of the integrity of the response of the HPA axis to stress.     

Adrenal androgen excess in the polycystic ovary syndrome: sensitivity and responsivity of the hypothalamic-pituitary-adrenal axis

Over 50% of patients with the polycystic ovary syndrome (PCOS) demonstrate excess levels of adrenal androgens (AAs), particularly dehydroepiandrosterone sulfate (DHS). Nonetheless, the mechanism for the AA excess remains unclear. It has been noted that in PCOS the pituitary and ovarian responses to their respective trophic factors (i.e. GnRH and LH, respectively) are exaggerated. Similarly, we have postulated that excess AAs in PCOS arises from dysfunction of the hypothalamic-pituitary-adrenal axis, due to 1) exaggerated pituitary secretion of ACTH in response to hypothalamic CRH, 2) excess sensitivity/responsivity of AAs to ACTH stimulation, or 3) both. To test this hypothesis we studied 12 PCOS patients with AA excess (HI-DHS; DHS, > 8.1 mumol/L or 3000 ng/mL), 12 PCOS patients without AA excess (LO-DHS; DHS, < 7.5 mumol/L or 2750 ng/mL), and 11 controls (normal subjects). Each subject underwent an acute 90-min ovine CRH stimulation test (1 microgram/kg) and an 8-h incremental i.v. stimulation with ACTH-(1-24) at doses ranging from 20-2880 ng/1.5 m2.h) with a final bolus of 0.25 mg. All patient groups had similar mean body mass indexes and ages, and both tests were performed in the morning during the follicular phase (days 3-10) of the same menstrual cycle, separated by 48-96 h. During the acute ovine CRH stimulation test, no significant differences in the net maximal response (i.e. change from baseline to peak level) for ACTH, dehydroepiandrosterone (DHA), androstenedione (A4), or cortisol (F) or for the DHA/ACTH, A4/ACTH, or F/ACTH ratios was observed. Nonetheless, the net response of DHA/F and the areas under the curve (AUCs) for DHA and DHA/F indicated a greater response for HI-DHS vs. LO-DHS or normal subjects. The AUC for A4 and A4/F and the delta A4/delta F ratio (delta = net maximum change) indicated that HI-DHS and LO-DHS had similar responses, which were greater than that of the normal subjects, although the difference between LO-DHS patients and normal subjects reached significance only for the AUC of the A4 response. No difference in the sensitivity (i.e. threshold or minimal stimulatory dose) to ACTH was noted between the groups for any of the steroids measured. Nonetheless, the average dose of ACTH-(1-24) required for a threshold response was higher for DHA than for F and A4 in all groups. No difference in mean responsivity (slope of response to incremental ACTH stimulation) was observed for DHA and F between study groups, whereas the responsivity of A4 was higher in HI-DHS patients than in normal or LO-DHS women. The net maximal and the overall (i.e. AUC) responses of DHA were greater for HI-DHS than for normal or LO-DHS women. The response of A4 and the delta A4/delta F ratio were greater for HI-DHS patients than for LO-DHS patients or normal subjects. Alternatively, HI-DHS and LO-DHS patients had similar overall responses (i.e. AUC) for A4 or A4/F, although both were greater than those of normal subjects. The relative differences in response to incremental ACTH stimulation between steroids was consistent for all subject groups studied, i.e. A4 > F or DHA. In conclusion, our data suggest that AA excess in PCOS patients is related to an exaggerated secretory response of the adrenal cortex for DHA and A4, but not to an altered pituitary responsivity to CRH or to increased sensitivity of these AAs to ACTH stimulation. Whether the increased responsivity to ACTH for these steroids is secondary to increased zonae reticularis mass or to differences in P450c17 alpha activity, particularly of the delta 4 pathway, remains to be determined.     

Endocrine profile and neuroendocrine challenge tests in transgenic mice expressing antisense RNA against the glucocorticoid receptor

A transgene expressing antisense RNA complementary to a fragment of the glucocorticoid receptor cDNA was incorporated into the mouse genome and resulted in a transgenic animal that has decreased glucocorticoid receptor function. The transgenic mice showed basal plasma ACTH and corticosterone levels similar to those of the normal control animals. We have further investigated changes in HPA axis regulation by use of different neuroendocrine challenge tests including a dexamethasone suppression test (DST). In comparison to normal mice, a tenfold higher dose of dexamethasone (i.e. 20 micrograms/100 g body weight) was required to suppress the basal corticosterone levels of transgenic mice. Dexamethasone (2 micrograms/100 g body weight) produced a long-lasting suppression of plasma ACTH and corticosterone levels in control mice, whereas in transgenic animals only a short-lasting decrease in ACTH levels was apparent. Corticotropin-releasing hormone (CRH) administration resulted in an enhanced response in plasma ACTH levels in transgenic mice, whereas the corticosterone response was markedly reduced. The discrepancy between ACTH and corresponding corticosterone secretions in transgenic mice could be attributed, in part, to a reduced sensitivity of the adrenal gland to stimulation by ACTH. Pituitaries of transgenic mice contained about 50% less proopiomelanocortin (POMC) mRNA than those of control animals. No significant differences were noted in the ACTH or protein contents of normal and transgenic mice pituitary glands although a slight increase in protein content of the transgenic mouse adrenal gland was apparent. In conclusion, transgenic mice with impaired GR function show major disturbances in HPA axis regulation which seem to be caused by the primary defect in conjunction with secondary modifications in, amongst others, pituitary CRH receptor system(s), sympathetic output and adrenal development. This mouse is therefore a useful model to study the consequences of life-long defective GR function and HPA axis regulation in general.     

Medication use patterns among demented, cognitively impaired and cognitively intact community-dwelling elderly people

OBJECTIVE: The present study was conducted in order to describe human hypothalamo-pituitary adrenal (HPA) axis adaptation in a model of repeated physical stress (endurance training) that causes a moderate increase in cortisol levels. SUBJECTS: We performed the same stimulation tests (adrenal stimulation with ACTH or pituitary stimulation with combined CRH/LVP) in a population of 8 endurance-trained athletes in two distinct situations: resting (baseline cortisol values) and 2 h after the end of strenuous exercise (increased cortisol values) to evaluate the HPA axis sensitivity to endogenous sustained increases in cortisol concentrations. MEASUREMENTS: During these tests, saliva and plasma cortisol (Fs and Fp, respectively) were assessed and compared. RESULT: Cortisol values in both plasma and saliva at the end of 2 h of exercise were significantly higher than in rested controls: Fs 11.5 +/- 1.3 vs 6.5 +/- 0.8 nmol.l-1 and Fp 428 +/- 36 vs 279 +/- 27 nmol.l-1 (post exercise vs post rest sessions, respectively, P < 0.001 for both). After either hormone test (CRH/LVP or ACTH), cortisol levels in plasma and saliva increased similarly when rest was compared to post exercise. Saliva variations (delta %) under exogenous hormone stimulation were dramatically greater than plasma variations. For example, under ACTH stimulation, the relative increments in cortisol were on control day: delta Fs 980 +/- 139 vs delta Fp 218 +/- 43% (saliva vs plasma, respectively, P < 0.05) and on exercise day: delta Fs 605 +/- 89 vs delta Fp 102 +/- 14% (saliva vs plasma, respectively, P < 0.05). CONCLUSIONS: In endurance-trained athletes, displaying a moderate but sustained endogenous cortisol increase: (1) ACTH responses following pituitary stimulation are not blunted, (2) cortisol responses following maximal adrenal stimulation are not blunted. Our results favour the hypothesis of a decreased pituitary sensitivity to cortisol negative feedback whereas the hypothesis of a major decreased adrenal sensitivity to ACTH was discarded. The greater ability of saliva assays to detect a cortisol increase strongly supports its use in the study of HPA physiology, whether under basal or dynamic conditions.     

Lesion load quantification in serial MR of early relapsing multiple sclerosis patients in azathioprine treatment. A retrospective study

Interactions between the hypothalamic-pituitary-adrenocortical (HPA) system and melatonin secretion have been demonstrated, but only the effects of melatonin on the activity of the HPA system have been studied in man. Alterations of melatonin secretion described as low-melatonin syndrome have been demonstrated in patients suffering from a major depressive episode, and an inhibitory factor on melatonin secretion has been postulated. We investigated whether corticotropin-releasing hormone (CRH), which is thought to be involved in HPA abnormalities in depressed patients, can also suppress melatonin secretion in healthy volunteers. Ten healthy male human volunteers in a double-blind study design received randomized hourly intravenous injections from 08.00 to 18.00 h that contained 10 micrograms human CRH, 1 microgram adrenocorticotropic hormone (ACTH), or placebo to simulate pulsatile hormone secretion. Plasma melatonin and cortisol responses during the treatment and nocturnal sleep electroencephalograms after the treatment were recorded. Administration of CRH reduced melatonin secretion significantly below values obtained after administration of placebo and ACTH. Cortisol secretion was significantly enhanced by ACTH in comparison to both placebo and CRH. Electroencephalographic sleep parameters revealed no treatment effects. Our findings suggest that CRH has an inhibitory effect on the pineal secretion of melatonin in normal man. A mechanism via a release of cortisol was not supported by our results. Secondary hormonal effects from changes in nocturnal sleep architecture were excluded. Further investigation of the action of CRH on melatonin secretion as well as the mutual feedback between the HPA system and the pineal gland may extend our knowledge of neuroendocrine alterations mediating the adaptive response to stress and the eventual involvement in the pathogenesis of depression.     

Excess corticotropin releasing hormone-binding protein in the hypothalamic-pituitary-adrenal axis in transgenic mice

Corticotropin-releasing hormone (CRH) is the primary hypothalamic releasing factor that mediates the mammalian stress response. The CRH-binding protein (CRH-BP) is secreted from corticotropes, the pituitary CRH target cells, suggesting that the CRH-BP may modulate hypothalamic-pituitary-adrenal (HPA) axis activity by preventing CRH receptor stimulation. Transgenic mice were generated that constitutively express elevated levels of CRH-BP in the anterior pituitary gland. RNA and protein analyses confirmed the elevation of pituitary CRH-BP. Basal plasma concentrations of corticosterone and adrenocorticotropin hormone (ACTH) are unchanged, and a normal pattern of increased corticosterone and ACTH was observed after restraint stress. However, CRH and vasopressin (AVP) mRNA levels in the transgenic mice are increased by 82 and 35%, respectively, to compensate for the excess CRH-BP, consistent with the idea that CRH-BP levels are important for homeostasis. The transgenic mice exhibit increased activity in standard behavioral tests, and an altered circadian pattern of food intake which may be due to transgene expression in the brain. Alterations in CRH and AVP in response to elevated pituitary CRH-BP clearly demonstrate that regulation of CRH-BP is important in the function of the HPA axis.     

Hypothalamic corticotropin-releasing hormone suppression during the postpartum period: implications for the increase in psychiatric manifestations at this time

The third trimester of human pregnancy is characterized by a hyperactive hypothalamic-pituitary-adrenal axis, possibly driven by progressively increasing circulating levels of placental CRH and gradually decreasing levels of CRH-binding protein. The postpartum period, on the other hand, is characterized by an increased vulnerability to psychiatric manifestations (postpartum "blues," depression, and psychosis), a phenomenon compatible with suppressed hypothalamic CRH secretion. To investigate the hypothesis that the postpartum period is associated with suppression of hypothalamic CRH secretion, we studied prospectively 17 healthy euthymic women (mean +/- SE age, 32.0 +/- 1.1 yr) with no prior history of depression, starting at the 20th week of gestation. Psychometric testing was performed monthly during pregnancy and postpartum on day 2 and weeks 2, 3, 6, 8, 12, 16, and 20, whereas serial ovine (o) CRH tests were performed postpartum at 3, 6, and 12 weeks. While pregnant, all 17 subjects remained euthymic; in the postpartum period, 7 women developed the "blues," and 1 developed depression. Overall, the mean plasma ACTH response to an iv bolus of 1 microgram/kg oCRH was markedly blunted at 3 and 6 weeks, but normal at 12 weeks postpartum, whereas the mean plasma cortisol response was at the upper limit of normal at all 3 times. These data are compatible with a suppressed hypothalamic CRH neuron that gradually returns to normal while hypertropic adrenal cortexes are progressively down-sizing. When the postpartum ACTH responses to oCRH were analyzed separately for the euthymic women and the women who had the "blues" or depression, the blunting of ACTH was significantly more severe and long lasting in the latter group; this was observed at all 3 times of testing. We conclude that there is central suppression of hypothalamic CRH secretion in the postpartum, which might explain the increased vulnerability to the affective disorders observed during this period. The suppressed ACTH response to oCRH might serve as a biochemical marker of the postpartum "blues" or depression.     

Ketoconazole attenuates the cortisol response but not the subjective effects of smoked cocaine in humans

Attenuation of hypothalamo-pituitary-adrenal (HPA) function in laboratory rodents has been found to reduce the reinforcing effects of cocaine. To examine whether attenuation of HPA function reduces the effects of cocaine in humans, one female and seven male 'crack' cocaine abusers were pretreated with three doses of ketoconazole (0, 600, 1200 mg), an inhibitor of adrenocorticoid biosynthesis, 1 h before receiving cocaine. Three doses of smoked cocaine (0, 12, 50 mg) were administered in counterbalanced order under each ketoconazole condition. Ketoconazole dose-dependently reduced cocaine-induced cortisol, but not adrenocorticotropin (ACTH) release, and attenuated the cocaine-induced increase in heart rate and blood pressure. Plasma ACTH levels were more predictive of blood pressure changes than either cocaine or cortisol levels. Suppression of cortisol secretion was not associated with a reduction in ratings of the subjective effects of cocaine. These results support a role for the HPA axis in the cardiovascular effects of cocaine, but do not support a role for the HPA axis in the subjective effects of cocaine. To the extent that self-administration can be predicted by subjective effects, these results further argue that the HPA axis does not play a critical role in cocaine self-administration by humans.     

The role of mineralocorticoid receptors in hypothalamic-pituitary-adrenal axis regulation in humans

In rodents, two types of glucocorticoid receptors, the mineralocorticoid (MR; type I) and the glucocorticoid (type II) receptors, have been demonstrated to play a role in hypothalamic-pituitary-adrenal (HPA) axis regulation. Because MR shows a very high affinity for cortisol, it has been suggested that MR plays an important role in restraint of CRH and ACTH secretion during the nadir of the circadian rhythm. Although a number of studies have established the importance of MR in rodents, the functional role of MR in humans has not been determined. These studies evaluated whether spironolactone, an MR antagonist, had a detectable effect on HPA axis regulation in humans, and whether the effect was greatest during the evening, when plasma cortisol concentrations are in the MR range. Compared to the placebo day, after a single dose of spironolactone at either 0800 or 1600 h, there is a significant increase in plasma cortisol, which is preceded by a rise in ACTH and beta-endorphin. A significant effect of spironolactone on cortisol secretion was demonstrated with no differences between the morning and evening. Because the effect of spironolactone on cortisol was short lived, a second experiment was conducted using two doses of spironolactone, again sampling in the morning and evening. After two doses of spironolactone, plasma cortisol levels showed a significant and sustained spironolactone-induced elevation for the entire sampling period. However, neither plasma beta-endorphin nor ACTH was increased compared to levels on the placebo day. These data suggest that MR appear to play a clear role in HPA axis regulation during the time of the circadian peak as well as the trough. Furthermore, MR blockade may affect the sensitivity of the adrenal to ACTH.