Response to corticotropin-releasing hormone during pregnancy in the baboon

CRH is secreted by the placenta into human maternal and fetal plasma during gestation. In the present study plasma CRH was measured in the plasma of five pregnant baboons and their fetuses to ascertain whether the baboon is a suitable model for study of placental CRH. Studies were performed in chronically catheterized animals that exhibited no behavioral or endocrinological signs of stress; maternal animals moved freely about the cage. Mean maternal plasma CRH was 620 +/- 110 pmol/L (2970 pg/mL) at 146 +/- 11 days gestation, and mean fetal plasma CRH was 133 +/- 29 pmol/L (640 pg/mL) at delivery in four animals. Plasma CRH was undetectable (less than 8.5 pmol/L; less than 41 pg/mL) in nonpregnant animals and in animals 8 h after delivery. Maternal and fetal plasma CRH levels in the chronically catheterized baboon were very similar to human maternal and umbilical cord CRH levels at comparable gestational ages. In addition, the majority of maternal plasma CRH eluted in the same position as synthetic human CRH by gel filtration. CRH stimulation tests were performed in the chronically catheterized maternal baboon to investigate whether pituitary-adrenal function during pregnancy is similar to that observed after chronic CRH infusion; blunted ACTH and cortisol responses to acute injections of CRH are observed after chronic CRH infusion. The administration of 0.5 micrograms/kg ovine CRH (oCRH) failed to result in an ACTH or cortisol rise in four pregnant baboons. Baseline ACTH levels were 5.2 +/- 0.4 pmol/L (23.5 pg/mL), and baseline cortisol levels were 800 +/- 55 nmol/L (29.1 micrograms/dL); neither rose after CRH administration. In contrast, 0.5 micrograms/kg oCRH did result in significant ACTH and cortisol elevations in five nonpregnant baboons [ACTH: baseline, 5.9 +/- 1.4; peak, 16 +/- 4.8 pmol/L (P less than 0.05); cortisol: baseline, 430 +/- 55 nmol/L; peak, 960 +/- 200 nmol/L (P less than 0.05)]. In contrast, the administration of a larger dose of oCRH (5.0 micrograms/kg) led to stimulation of ACTH release in five pregnant baboons (baseline, 6.6 +/- 1.3 pmol/L; peak, 34.1 +/- 6.4; P less than 0.001). After this dose cortisol levels also rose in the pregnant animals (baseline = 1040 +/- 30 nmol/L; peak, 1620 +/- 130); however, this response was blunted compared to that in the nonpregnant animals (P less than 0.05). CRH (5.0 micrograms/kg) significantly stimulated both ACTH and cortisol in the nonpregnant animals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Responses to corticotropin-releasing hormone and its bound and free forms in pregnant and nonpregnant women

Plasma CRH levels are considerably higher in women during the third trimester of pregnancy than in non-pregnant women. Most of plasma CRH in pregnant women is bound to CRH-binding protein (CRH-BP). To gain further insight into CRH physiology during pregnancy, we measured the responses of plasma ACTH and cortisol and the changes in bound and free forms of CRH in plasma after human CRH administration (2 micrograms/kg) in five pregnant (39-40 weeks of pregnancy) and five nonpregnant women. The mean basal plasma ACTH and cortisol levels in the pregnant women were higher than those in the nonpregnant women. However, the maximum increments in plasma ACTH and cortisol levels and the integrated ACTH and cortisol responses, after subtraction of the basal levels after CRH administration, were similar in the two groups. The plasma CRH half-time in the pregnant group was similar to that in the nonpregnant group. The mean basal plasma CRH level in the nonpregnant women was 1.5 +/- 0.2 (+/- SE) pmol/L, and that in the pregnant women was 360 +/- 35 pmol/L. On gel filtration chromatography, almost all of the CRH in the plasma was protein bound (320 +/- 30 pmol/L) in the pregnant women; no CRH peaks were detected in nonpregnant women because of the low plasma CRH levels. After CRH administration, the level of the bound form of plasma CRH was highest at 5 min, and then declined to a plateau at 15 min and 30 min in the pregnant women. In the nonpregnant women, protein-bound CRH also was highest at 5 min, but it progressively declined thereafter. The disappearance rate of the bound CRH in plasma from the nonpregnant women was similar to that of the second compartment of the plasma decay curves of the free CRH from both groups. We conclude that the plasma ACTH and cortisol responses to exogenous CRH are similar in pregnant and nonpregnant women, the effect of CRH-BP on the disappearance of plasma CRH is minimal, and plasma CRH-BP in pregnant women has the capacity to bind additional CRH.     

Immunoreactive corticotropin-releasing hormone in human plasma during pregnancy, labor, and delivery

We previously reported that immunoreactive corticotropin-releasing hormone (CRH) is present in human placenta and third trimester maternal plasma, and that such material is very similar to rat CRH and the predicted structure of human CRH. We suggested that maternal plasma immunoreactive CRH may be of placental origin. To further investigate this possibility, we measured plasma immunoreactive CRH in women during pregnancy, labor, and delivery and 1 and 2 h postpartum, and in nonpregnant women. Umbilical cord plasma and placental CRH concentrations were also measured. In the first trimester of pregnancy, the mean maternal plasma level was 5.9 +/- 1.0 pg (+/- SEM)/ml (n = 24), not significantly different from that in 10 nonpregnant women (5.8 +/- 0.8 pg/ml). Plasma CRH concentrations progressively increased during pregnancy (second trimester, 35.4 +/- 5.9 pg/ml (n = 39); early third trimester (28-34 weeks), 263 +/- 41 pg/ml (n = 14); late third trimester (35-40 weeks), 800 +/- 163 pg/ml (n = 20)]. There was a significant correlation between maternal plasma CRH levels and weeks of pregnancy. Plasma CRH concentrations were further elevated (2215 +/- 329 pg/ml; n = 9). During early labor, peaked at delivery (4409 +/- 591 pg/ml; n = 28), and declined rapidly after delivery [1 h postpartum, 1042 +/- (353 pg/ml (n = 13); 2 h postpartum, 346 +/- 91 pg/ml (n = 13)]. There was a significant correlation (r = 0.562; P less than 0.01) between matched maternal plasma and placental CRH concentrations. The mean umbilical cord plasma CRH level (50.6 +/- 6.1 pg/ml; n = 28) was much lower than that in the mother at the time of delivery. Umbilical venous plasma CRH levels were significantly greater than those in simultaneously obtained umbilical arterial plasma (70.8 +/- 11.3 and 41.8 +/- 4.9 pg/ml, respectively; n = 11). There was a significant correlation (r = 0.384; P less than 0.05) between maternal and fetal CRH concentrations. Gel filtration of plasma obtained from women during the third trimester, at delivery, and early postpartum and placental extracts revealed two major peaks of immunoreactive CRH: a high mol wt peak and one at the elution position of rat CRH. In contrast, only rat CRH-sized material was detected in plasma from nonpregnant women and umbilical cord plasma. Maternal plasma immunoreactive CRH-sized material stimulated ACTH release from anterior pituitary tissue in a dose-dependent manner and was equipotent with rat CRH.(ABSTRACT TRUNCATED AT 400 WORDS)     

Adrenocorticotropin and cortisol responses to vasopressin during pregnancy.

CRH is secreted by the placenta into the maternal and fetal circulation during pregnancy in humans and non-human primates. ACTH and cortisol responses to exogenous CRH are blunted during pregnancy. In the present study we examined the pituitary-adrenal response to another corticotropin releasing factor, vasopressin. Studies were performed in chronically catheterized female baboons moving freely in their home cages; 13 studies were performed in 4 pregnant animals, and 8 studies were performed in 6 nonpregnant animals. Vasopressin was administered iv in 2 doses (0.3 and 3.0 U), and plasma samples were obtained for CRH, ACTH, and cortisol measurements. Results are expressed as the mean +/- SEM. Baseline plasma CRH was 240 +/- 20 pmol/L in the pregnant animals and unmeasurable (less than 20) in the nonpregnant animals. In the pregnant animals, ACTH concentrations rose from a baseline of 6.4 +/- 1.3 pmol/L to 10.1 +/- 0.4 after 0.3 U vasopressin and to 24.9 +/- 5.2 after 3.0 U vasopressin. In the nonpregnant animals, ACTH levels were 5.8 +/- 1.3 at baseline, 6.7 +/- 1.3 after the 0.3-U dose, and 14.6 +/- 2.4 after the 3.0-U dose. The peak ACTH response after each dose of vasopressin was higher in the pregnant animals than in the nonpregnant animals (P less than 0.05). The baseline cortisol level in the pregnant animals was 960 +/- 80 nmol/L and rose to 1370 +/- 110 and 1535 +/- 165 after the 2 doses of vasopressin, respectively. The baseline cortisol concentration in the nonpregnant animals was 910 +/- 86 nmol/L. The cortisol level was 990 +/- 75 after the 0.3-U vasopressin dose and 1380 +/- 140 after the 3.0-U dose. The peak cortisol response after the 0.3-U dose was significantly higher in the pregnant animals (P less than 0.02), while the peak cortisol responses after the 3.0-U dose were similar in the 2 groups of animals. In a single animal, vasopressin was administered sequentially at 4 gestational ages during pregnancy and then 2 times in the postpartum period. The ACTH response to vasopressin increased as pregnancy progressed and then decreased in the postpartum period. In summary, the ACTH and cortisol responses to 0.3 and 3.0 U vasopressin, iv, are enhanced during pregnancy in the baboon, although the responses to exogenous CRH are blunted during gestation. We conclude that the chronic placental CRH stimulation of the pituitary-adrenal axis during pregnancy leads to an enhanced response to vasopressin and a down-regulation of the response to exogenous CRH.     

Plasma corticotropin-releasing hormone concentrations during pregnancy and parturition

Plasma CRH was measured in maternal plasma throughout the third trimester of pregnancy, during labor, and postpartum. CRH levels were also measured in arterial and venous umbilical cord plasma samples. In normal pregnant women, plasma CRH increased from 50 +/- 15 (+/- SEM) pg/mL at 28 weeks gestation (n = 41) to 1462 +/- 182 pg/mL at 40 weeks (n = 55) and 1680 +/- 101 pg/mL (n = 65) in labor. Women with pregnancy-induced hypertension (n = 49) had plasma CRH levels significantly elevated above this normal range. Similarly, women who subsequently went into premature labor had raised levels several weeks before the onset of labor. After delivery, plasma CRH returned to normal within 15 h. Total plasma cortisol levels varied little throughout the third trimester, but increased during labor and remained elevated 2-3 days postpartum. There was, therefore, no correlation between plasma cortisol and CRH, implying that this placental CRH is not primarily involved in the control of the maternal hypothalamo-pituitary adrenal axis during pregnancy. The concentrations of CRH in umbilical cord plasma samples were considerably lower than those in the maternal circulation and were close to those in normal nonpregnant adults.     

High levels of corticotropin-releasing hormone immunoactivity in maternal and fetal plasma during pregnancy

Corticotropin-releasing hormone immunoactivity (CRHi) was measured in the plasma of 31 pregnant women and 6 nonpregnant women as well as in the umbilical cord plasma of 40 term fetuses. CRHi was not detectable (less than 44 pg/ml) in the plasma of 6 nonpregnant women or in 6 women in the first trimester of pregnancy. Mean plasma CRHi rose progressively to 58 +/- 18 and 270 +/- 68 pg/ml during the second and third trimesters, respectively, and again became undetectable within 24 h after delivery. Mean CRHi in 40 umbilical cord plasma samples was 136 +/- 16 pg/ml. Gel filtration of both fetal and maternal plasma showed that the majority of the CRHi eluted in the same position as synthetic human CRH. There was no significant correlation between CRHi and either beta-endorphin or ACTH in umbilical cord plasma, suggesting that this CRHi may not be primarily responsible for the release of beta-endorphin and ACTH into fetal plasma at delivery. A close correlation (r = 0.82) was found between simultaneously obtained maternal and umbilical cord plasma CRHi in 10 maternal-fetal pairs, supporting a common source for this peptide in maternal and fetal circulation. A placental source for fetal and maternal CRHi was suggested by the finding of a higher CRHi concentration in the umbilical vein than in the umbilical artery and by the disappearance of this peptide from maternal plasma after delivery. We conclude that a large amount of CRHi is secreted by the placenta into both the maternal and fetal circulation during pregnancy and suggest that this may be an important modulator of the maternal and fetal hypothalamic-pituitary-adrenal axis during gestation.     

Impaired beta-endorphin response to human corticotropin-releasing hormone in obese children

In order to evaluate the secretion of beta-endorphin in obese children and adolescents, we measured plasma beta-endorphin, ACTH and cortisol levels before and following administration of CRH (1 microgram/kg). Fourteen normal weight and 22 obese subjects (weight excess ranging from 30 to 98%) were studied. Plasma hormone levels were measured by radioimmunoassay directly in plasma (cortisol, ACTH) and after silicic acid extraction and Sephadex G-75 column chromatography (beta-endorphin). Basal beta-endorphin levels in obese children were significantly higher than in controls (14.7 +/- 1.8 vs 6.0 +/- 0.6 pmol/l; mean +/- SEM). No differences were found in basal ACTH and cortisol levels. CRH administration significantly increased beta-endorphin, ACTH and cortisol levels in normal subjects and ACTH and cortisol levels in obese subjects. Plasma beta-endorphin levels in obese children and adolescents did not show any significant increment. These data confirm the higher than normal beta-endorphin plasma levels in obese subjects in childhood and demonstrate that CRH is unable to increase beta-endorphin levels, suggesting an impairment of the hypothalamo-pituitary control mechanisms or an extra-anterior pituitary source.     

Limited clinical usefulness of plasma corticotropin-releasing hormone, adrenocorticotropin and beta-endorphin measurements as markers of lung cancer.

We measured plasma corticotropin-releasing hormone (CRH), ACTH, beta-endorphin (beta-EP), and cortisol levels as possible tumor markers in a sequence of 103, randomly selected, patients with lung cancer but without the ectopic Cushing's syndrome and in 72 age- and sex-matched controls. Plasma CRH levels of cancer patients were similar to those of controls both in patients sampled in the morning or in the afternoon. On the other hand, plasma ACTH levels of cancer patients were significantly higher than control patients both in the morning and in the afternoon and showed a preserved circadian rhythm. However, about 35% of cancer patients sampled in the morning and about 60% of those sampled in the afternoon had ACTH levels within the 95% confidence interval (CI) of controls. Also plasma beta-EP levels were more elevated in cancer patients than controls in the morning but about 33% of them and about 80% of those sampled in the afternoon had beta-EP levels within the 95% CI of controls. Despite the higher plasma ACTH levels, cancer patients had cortisol plasma levels similar to controls with preserved circadian rhythm. In conclusion, although mean plasma ACTH and beta-EP were higher in patients affected by lung cancer, their measurements, as well as those of CRH, have practically no diagnostic value. Perhaps measurement of ACTH levels in the bronchial lavage may be more helpful.     

The corticotrophin releasing hormone test in late pregnancy: lack of adrenocorticotrophin and cortisol response

Biologically active corticotrophin-releasing-hormone (CRH) is produced by the placenta in large amounts and can be measured in the maternal circulation during third trimester of pregnancy. Its physiological significance is unknown. To further investigate the action of CRH in pregnancy, we performed a standard CRH-test (1 micrograms/kg synthetic human CRH) in seven pregnant women 1 week prior to their calculated delivery data and 4-5 weeks post-partum. No response of plasma ACTH to CRH administration could be measured in any of the third trimester pregnant women. Post-partum, basal ACTH levels were significantly lower (1.6 +/- 0.3 vs 5.3 +/- 0.2 pmol/l) and reacted promptly to CRH administration (1.6 +/- 0.3-4.2 +/- 0.5 pmol/l; P less than 0.05). Concentration of cortisol in plasma and salivary cortisol paralleled the ACTH response to administration of CRH. However, one pregnant woman experienced physical and emotional stress during the CRH-test and reacted with a sharp rise in cortisol secretion. The lack of the ACTH and cortisol response in this study to exogenously administered CRH in third trimester pregnancy may be due to high circulating glucocorticoid concentrations, desensitization of the pituitary corticotroph and/or in part due to circulating specific CRH-carrier protein.     

Plasma GHRH, CRH, ACTH, beta-endorphin, human placental lactogen, GH and cortisol concentrations at the third trimester of pregnancy

The aim of the study was to determine the concentration of GHRH and CRH in maternal plasma during the 3rd trimester of pregnancy and to search for the possible correlations with related hormones such as ACTH, beta-endorphin, cortisol, GH and human placental lactogen. Patients consisted of 31 healthy pregnant women (20-39 years) divided according to duration of pregnancy into 2 groups: I. from 26 to 32 pregnancy week N = 13), II. from 33 to 39 week (N = 18), and of 7 women evaluated 3 days after delivery. All listed hormones except ACTH were measured by RIA (GHRH, CRH and beta-endorphin-like immunoreactivity after extraction with silic acid) and ACTH by IRMA. In the late 3rd trimester plasma levels of CRH (P less than 0.001), ACTH (P less than 0.02), beta-endorphin (P less than 0.05), cortisol (P less than 0.025), as well as GHRH (P less than 0.002) and human placental lactogen (hPL) (P less than 0.001) were increased in comparison to early 3rd trimester, whereas 3 days after delivery CRH and GHRH became undetectable and those of ACTH and cortisol decreased significantly. The CRH plasma concentrations were found to be strongly correlated with gestational age (r = 0.86, P less than 0.001) but not with ACTH and cortisol. GHRH levels correlated mainly with human placental lactogen concentrations (r = 0.64, P less than 0.001). CONCLUSION: In maternal plasma at the 3rd trimester of pregnancy, apart from the known markedly elevated CRH, the GHRH level was also raised. Strong correlations between CRH and gestational age and those between GHRH and human placental lactogen suggest that there is a relationship between these neurohormones and the placental function.     

The relationship of saline-induced changes in vasopressin secretion to basal and corticotropin-releasing hormone-stimulated adrenocorticotropin and cortisol secretion in man

To investigate the effect of endogenous arginine vasopressin (AVP) on ACTH secretion, normal subjects were given infusions of either hypertonic saline (HS) or isotonic saline (NS) combined with human corticotropin-releasing hormone (CRH) or placebo. Basal plasma AVP was 2.3 +/- 0.3 (+/- SE) pg/ml, did not change with NS treatment, and rose to 5.4 +/- 0.6 pg/ml during HS infusion (P less than 0.01). Both basal and CRH-stimulated plasma ACTH and cortisol concentrations increased during HS infusion. Peak plasma ACTH and cortisol levels were 11.4 +/- 1.5 pg/ml and 8.6 +/- 0.8 micrograms/dl, respectively, during the HS (plus placebo) infusion. During the NS (plus placebo) infusion, plasma ACTH and cortisol gradually declined to 6.8 +/- 0.5 pg/ml and 2.6 +/- 0.4 micrograms/dl. The timing of the rise in ACTH during the HS infusion paralleled the rise in AVP. When an iv dose of 1 microgram/kg CRH was administered during the saline infusions, peak plasma ACTH and cortisol levels were 27.7 +/- 6.3 pg/ml and 17.5 +/- 1.0 micrograms/dl, respectively, during the HS infusion and 15.6 +/- 1.7 pg/ml and 13.4 +/- 1.2 micrograms/dl during the NS infusion. When the areas under the hormone response curves were compared, CRH stimulated ACTH and cortisol secretion to a greater extent than did HS (P less than 0.05). The hormonal stimulation due to combined CRH and hypertonic saline was greater than that attributable to either factor alone (P less than 0.025), but was not different than the sum of the effects of the individual factors. These results indicate that increases in endogenous AVP produced by HS are associated with increases in both basal and CRH-stimulated ACTH and cortisol release. The effect of HS appears to be additive to but not consistently synergistic with the effect of CRH.     

The maternal hypothalamic–pituitary–adrenal axis in the third trimester of human pregnancy

OBJECTIVE The third trimester of pregnancy is characterized by a mildly hyperactive hypothalamic–pituitary–adrenal (HPA) axis, possibly driven by elevated circulating levels of corticotrophin releasing hormone (CRH) of placental origin. In-vitro studies have demonstrated that glucocorticoids and oestrogen stimulate while progesterone inhibits the expression of CRH mRNA and/or protein, suggesting that several potential interactions between the placenta and the HPA axis may exist. DESIGN AND PATIENTS To investigate the detailed pattern of circulating immunoreactive (ir) CRH, ACTH, cortisol, oestradiol and progesterone during the third trimester of pregnancy, plasma samples were drawn serially every 30 minutes from 22 healthy pregnant women (age 32.0 ± 1.1 years, mean ± SE) between the 34th and 36th week of gestation. Ten women had plasma samples drawn between 0800 h and 2000 h (daytime group), and 12 between 2000 h and 0800 h (night-time group). The hormone concentrations obtained were analysed for pulsatility by the Detect program, for detection of circadian rhythmicity by comparison between the first and second 6-hour periods within each group by Student's t-test, and for time-dependent correlations by cross-correlation analysis. RESULTS All five hormones were secreted in a pulsatile fashion. There was no apparent circadian rhythm of CRH or oes tradiol secretion, whereas there was a clear circadian rhythm in plasma ACTH, cortisol and progesterone secretion, with the latter in reverse phase (P<0.05). No significant correlations were observed between CRH and ACTH, whereas, as expected, ACTH and cortisol concentrations were strongly correlated with each other over time (r=0.32 and 0.70 at lag time 30 minutes for the daytime and night-time groups, respectively), with ACTH leading cortisol. A weak positive correlation was observed between CRH and cortisol concentrations for the night-time group at lag time 0 minute, suggesting that the latter may have a positive effect on the former in vivo CONCLUSIONS These data suggest that placental CRH, although pulsatile, drives quantitatively the maternal HPA axis in the third trimester of pregnancy in a non-circadian, non-pulsatile fashion. The maternal HPA axis is probably driven in a circadian and pulsatile fashion by another major ACTH secretagogue, most likely AVP of parvocellular paraventricular nucleus origin.     

DIURNAL SALIVARY CORTISOL PATTERNS DURING PREGNANCY AND AFTER DELIVERY: RELATIONSHIP TO PLASMA CORTICOTROPHIN-RELEASING-HORMONE

The circadian rhythm of salivary cortisol was studied in 10 healthy women every 4 weeks throughout pregnancy. In addition, in 12 women the diurnal patterns of salivary cortisol, serum cortisol, plasma ACTH, plasma CRH and serum progesterone were analysed in late third trimester pregnancy and again 3-5 days after delivery. Salivary cortisol profiles exhibited a clear circadian rhythm during pregnancy with an increase in mean salivary cortisol from the 25th to 28th week onwards reaching concentrations in late pregnancy more than twice as high as in non-pregnant controls, rapidly returning to normal concentrations after delivery. The coefficient of variation of salivary cortisol profiles decreased in third trimester pregnancy due to a parallel upward shift of cortisol concentrations (40.2 +/- 3.4% vs 77.6 +/- 6.6% after delivery, P less than 0.01). A diurnal pattern was also found for plasma ACTH and serum cortisol before and after delivery with lower concentrations post-partum (P less than 0.01). In late pregnancy, progesterone concentrations were significantly higher in the evening (930 +/- 85 nmol/l vs 813 +/- 74 nmol/l at 0900 h, P less than 0.01) but showed no diurnal variation post-partum. Plasma CRH was significantly elevated in late third trimester pregnancy (1.22 +/- 0.23 micrograms/l at 0900 h) but showed no diurnal change (1.30 +/- 0.28 micrograms/l at 1900 h). Moreover, no correlation between the free cortisol increase in late pregnancy and plasma CRH was noted despite a wide range of CRH levels (0.13-3.60 micrograms/l). In contrast, a significant correlation was observed between the serum progesterone increase and the salivary cortisol increase in late pregnancy (r = 0.70, P less than 0.05). These findings demonstrate that placental CRH is not the only regulator of maternal ACTH and cortisol release. Instead, our study suggests that placental CRH has little influence on baseline maternal adrenocortical function in pregnancy. The elevated salivary cortisol levels in pregnancy may be explained by glucocorticoid resistance owing to the antiglucocorticoid action of high progesterone concentrations.     

Serotoninergic receptor activation by dextrofenfluramine enhances the blunted pituitary-adrenal responsiveness to corticotropin-releasing hormone in obese subjects.

To explore the interrelationships between the serotoninergic system and the hypothalamic-pituitary-adrenal (HPA) axis in human obesity, we evaluated cortisol and adrenocorticotropic hormone (ACTH) response to synthetic human corticotropin-releasing hormone (hCRH, 1 microgram/kg intravenously [IV]) before and after stimulation of the serotoninergic system by dextrofenfluramine (d-FF, 30 mg/d for 3 months) in nine obese women. These responses were compared with a CRH test (1 microgram/kg) carried out in nine age-matched normal-weight women. Plasma cortisol of obese subjects did not significantly increase after CRH (peak value 127.1 +/- 11.2 ng/mL v 104.1 +/- 9.5 ng/mL). This response was lower (P less than .005) than in the controls, in whom the basal cortisol value of 120.6 +/- 11.8 ng/mL reached a peak value of 221.2 +/- 13.4 ng/mL. However, after administration of d-FF, CRH significantly increased (P less than .0001) plasma cortisol (peak value 170.6 +/- 18.0 ng/mL v 111.5 +/- 10.8 ng/mL) and the response was enhanced (P less than .05) as compared with that obtained before d-FF. The ACTH levels of our patients showed a small increment after CRH injection (peak value 13.5 +/- 1.7 pg/mL v 9.6 +/- 1.1 pg/mL), but the hormonal response was lower (P less than .005) than in controls (peak value 38.1 +/- 5.5 pg/mL v 13.8 +/- 0.8 pg/mL). However, after d-FF, CRH induced a significant increment (P less than .05) in plasma ACTH at 30 minutes (20.4 +/- 3.7 pg/mL v 10.9 +/- 0.9 pg/mL) and 45 minutes (18.0 +/- 2.6 pg/mL), even though this response was not significantly different from that observed before d-FF administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

The responses of plasma adrenocorticotropin and cortisol to corticotropin-releasing hormone (CRH) and cerebrospinal fluid immunoreactive CRH in anorexia nervosa patients

Pituitary-adrenocortical responses to the iv injection of 100 micrograms synthetic ovine corticotropin-releasing hormone (CRH) were studied in 13 patients with anorexia nervosa, and the concentrations of immunoreactive CRH in cerebrospinal fluid were measured in 7 of them. Mean basal levels of plasma ACTH and cortisol were 32 +/- 5 pg/ml (+/- SEM) and 21.1 +/- 1.5 micrograms/dl, respectively. The latter value was significantly higher than that in age-matched normal women (P less than 0.005). The mean increments of plasma ACTH and cortisol in response to CRH injection in those 13 patients were 21 +/- 5 pg/ml and 5.3 +/- 1.7 micrograms/dl, respectively, significantly lower than those in normal women (58 +/- 6 pg/ml and 15.3 +/- 7.7 micrograms/dl, respectively; P less than 0.005). When 4 patients were reexamined after weight gains of between 3 and 22 kg, their responses to the CRH injection increased. The mean concentration of immunoreactive CRH in the cerebrospinal fluid of seven patients was 30.8 +/- 3.9 pg/ml (+/- SEM), which was higher than the value of 18.4 +/- 1.1 pg/ml (P less than 0.005) in control subjects with cervical spondylosis. These findings suggest the possibility that hypersecretion of CRH may occur in patients with anorexia nervosa.     

Ovine corticotropin-releasing hormone stimulation test in normal children

We administered ovine corticotropin-releasing hormone (CRH) as a bolus iv injection (1 microgram/kg) to 21 normal boys and girls, aged 6-15 yr. CRH stimulated release of immunoreactive ACTH and cortisol in all children. The peak plasma ACTH and cortisol levels after CRH were 15.7 +/- 9.4 (SD) pg/ml and 14.3 +/- 3.6 micrograms/dl, respectively, in the girls, and 20.7 +/- 9.7 pg/ml and 16.6 +/- 3.3 micrograms/dl, respectively, in the boys. Plasma ACTH and cortisol responsiveness to CRH did not differ between girls or boys, or between children and adults. Cortisol-binding globulin concentrations in plasma did not change with age. We conclude that CRH provides a safe means of stimulating the pituitary-adrenal axis in children.     

Direct measurement of human plasma corticotropin-releasing hormone by "two-site" immunoradiometric assay

A "two-site" immunoradiometric assay (IRMA) which allows the direct estimation of human CRH (hCRH) in plasma is described. Using this IRMA, basal levels of CRH in normal subjects ranged from 2-28 pg/mL [mean, 15 +/- 7 (+/- SD) pg/mL; n = 58]. Values in men and women were similar. Plasma CRH values within this range were also found in patients with Cushing's syndrome, Addison's disease, and Nelson's syndrome, with no correlation between plasma CRH and ACTH levels in these patients. Elevated plasma CRH levels were found in pregnant women near term [1462 +/- 752 (+/- SD) pg/mL; n = 55], and the dilution curve of this CRH-like immunoreactivity paralleled the IRMA standard curve. After its immunoadsorption from maternal plasma, this CRH-like material eluted on reverse phase high performance liquid chromatography with a retention time identical to that of synthetic CRH and had equipotent bioactivity with the synthetic peptide in the perfused anterior pituitary cell bioassay. Circulating CRH was not detected in Wistar rats, even after adrenalectomy and subsequent ether stress. Synthetic hCRH was degraded by fresh human plasma relatively slowly; 65% of added CRH remained after 1 h of incubation at 37 C. Degradation was inhibited by heat treatment (54 C; 1 h), cold treatment (4 C; 4 h), or freezing and thawing. Loss of synthetic rat CRH occurred more rapidly when fresh rat plasma was used; only 20% of added CRH remained under the same conditions. The inability to measure CRH in peripheral rat plasma may be due to the presence of active CRH-degrading enzymes which fragment the CRH molecule into forms not recognized by the CRH IRMA.     

During a corticotropin-releasing hormone test in healthy subjects,administration of a beta-adrenergic antagonist induced secretion of cortisol and dehydroepiandrosterone sulfate and inhibited secretion of ACTH

OBJECTIVE: In chronic inflammatory diseases, serum levels of dehydroepiandrosterone (DHEA) sulfate (DHEAS) are low. Interestingly, several non-inflammatory diseases display similarly low levels of DHEAS which points to other inhibitory factors such as an activated sympathetic nervous system (SNS) (e.g. in patients with heart failure, fibromyalgia, or cancer cachexia). We aimed to identify the influence of the SNS tone on stimulated adrenal steroid secretion in 16 male and 12 female healthy subjects. METHODS: One group were given oral propranolol 2 h before a corticotropin-releasing hormone (CRH) test, and levels of adrenocorticotropin (ACTH), cortisol, 17-hydroxyprogesterone (17OHP), androstenedione, DHEA, and DHEAS were measured. RESULTS: Propranolol treatment decreased heart rate (by 20%), diastolic blood pressure (by 20%), and plasma ACTH, and increased serum cortisol, serum DHEAS, and the molar ratio of cortisol/17OHP, cortisol/DHEA, and DHEAS/DHEA similarly in female and male subjects. CONCLUSIONS: A beta-adrenergic influence seems to decrease CRH-stimulated cortisol in relation to ACTH and 17OHP, and decreases DHEAS in relation to DHEA. Although other workers have found beta-adrenergic stimulation of steroid secretion in cultured adrenocortical cells, the overall systemic influence of the SNS via beta-adrenoceptors seems to inhibit adrenal steroids under unstimulated and stimulated conditions. Sympathetic hyperactivity may be a common denominator for low levels of DHEAS in inflammatory and non-inflammatory diseases.     

Responsivity of adrenocorticotropin to corticotropin-releasing hormone and lack of suppressibility by dexamethasone are related phenomena in Cushing's disease

The ACTH and cortisol responses to 100 micrograms ovine corticotropin-releasing hormone (CRH) in 19 consecutive patients with Cushing's disease were compared with those in 13 normal subjects. In 2 patients with Cushing's disease, plasma ACTH and cortisol did not increase after CRH administration. Compared to the normal subjects, maximal ACTH increments [135 +/- 25 (+/- SEM) vs. 42 +/- 6 pg/ml; P less than 0.001, by Wilcoxon's two-sample test] and maximal cortisol increments (17.7 +/- 1.8 vs. 9.4 +/- 1.1 micrograms/100 ml; P less than 0.01 by Wilcoxon's test) after CRH were significantly higher in the 17 CRH-responsive patients with Cushing's disease. In the normal subjects, there was a significant negative correlation between the basal cortisol level and the maximal ACTH (r = -0.65; P less than 0.05, by Spearman's rank correlation test) and cortisol (r = -0.95; P less than 0.001, by Spearman's test) responses to CRH. In contrast, in the CRH-responsive Cushing patients, there was no significant correlation between the basal cortisol level and the maximal ACTH (r = 0.10; P greater than 0.10, by Spearman's test) and cortisol (r = 0.14; P greater than 0.10, by Spearman's test) increments after CRH treatment. In the normal subjects, there was no significant correlation between the basal ACTH level and the maximal ACTH increments after CRH administration (r = -0.24; P greater than 0.10, by Spearman's test). Again in contrast, in the CRH-responsive Cushing patients, maximal ACTH increments after CRH treatment correlated positively with basal ACTH levels (r = 0.69; P less than 0.005, by Spearman's test). Moreover, in these patients, the maximal ACTH increments after CRH were positively correlated with the ACTH levels after suppression with higher and lower doses of dexamethasone. We conclude that in Cushing's disease, unlike in normal subjects, circulating cortisol is not the major modulator of ACTH and cortisol responses to CRH, and that in these patients, responsivity of ACTH to CRH and lack of suppressibility by dexamethasone are related phenomena.     

Enhancement of plasma corticotropin-releasing hormone in pregnancy-induced hypertension

The role of a high CRH level in normal pregnancy remains unknown. Therefore we evaluated the concentrations of CRH and the related hormones in patients with pregnancy-induced hypertension. Fourteen women with pregnancy-induced hypertension, aged 20-39, at 30-39 gestational week, were investigated. The control group consisted of 20 healthy pregnant women matched according to gestational age. Plasma CRH beta-endorphin-like immunoreactivity, cortisol, and human placental lactogen were measured by radioimmunoassay, ACTH by an immunoradiometric method. It was found that in hypertensive patients the mean CRH concentration was significantly higher (4257 +/- 840 (SEM) ng/l) than that in healthy pregnant women (1083 +/- 227 ng/l, p less than 0.001). The concentration of ACTH, however, was only slightly higher 65.0 +/- 6.0 vs 50.7 +/- 2.5 ng/l p less than 0.025, whereas the differences in beta-endorphin, cortisol and human placental lactogen were not significant. In both groups there was no correlation between the CRH level and those of the related hormones. In healthy pregnant women the CRH level closely correlated with gestational age (r = 0.76, p less than 0.001), whereas in patients with hypertension no such correlation was present (r = 0.29). We assume that the marked enhancement of plasma CRH in pregnancy-induced hypertension is probably caused by its decreased breakdown in ischemic placental tissue, but its increased synthesis in the placenta and its indirect counterregulatory hypotensive role must also be considered.