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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human placenta has been implicated as a source of numerous peptide hormones during pregnancy. Since the immunoassay detection of the proopiomelanocortin derived peptide beta-endorphin (beta E) in placental extracts in 1978, it has remained uncertain whether placental beta E immunoreactivity (IR) is 1) secreted into the maternal circulation and 2) opiate receptor active during pregnancy. To elucidate the nature of beta E IR in the placenta, both beta E IR and N-alpha-acetylated beta E (Ac beta E) IR were simultaneously measured in extracts of human pituitaries, placentas, and plasma by two homologous RIAs. Pituitary extracts (n = 6) contained 38 +/- 7 nmol beta E IR per g wet wt tissue (mean +/- SEM), of which only 20 +/- 4 pmol/g were Ac beta E IR. Term placental extracts (n = 19) had 201 +/- 30 fmol/g wet wt total beta E IR and 30 +/- 3 fmol/g wet wt total Ac beta E IR, which comprised 15% of total beta E IR in placental extracts. Total plasma beta E IR rose from 28 weeks gestation (8.5 +/- 0.3 fmol/mL, n = 159) to peak at labor (50 +/- 4 fmol/mL, n = 98; P < 0.01) but total Ac beta E IR was found in only four 28-week (1.7 +/- 0.9 fmol/mL) and 42 labor plasma samples (0.9 +/- 0.1 fmol/mL). Gel filtration chromatography of placental and pituitary extracts showed that while less than 1% of the beta E31-size material was acetylated in the pituitary, up to 60% of the beta E31-size material in placental extracts was acetylated. In pooled third trimester plasma extracts, however, only 4% of the beta E31-size material was acetylated. Furthermore, the ratio of beta E31:beta-lipotropin in pituitary extracts (n = 3) was 0.5; pooled plasma-0.5, and placental extracts (n = 5)-1.2. These data indicate that 1) the placenta extensively N-alpha-acetylates beta E31 destroying its opiate bioactivity while the pituitary does not; 2) beta E IR in pregnant women's plasma is similar to pituitary beta E IR, being mostly nonacetylated and similar in size to beta-lipotropin. These findings are consistent with a pituitary source for the elevated plasma beta E IR found during late pregnancy which may, in turn, be a consequence of elevated plasma concentrations of placentally secreted plasma corticotropin-releasing factor IR present during the third trimester.
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PMID:Beta-endrophin immunoreactivity during human pregnancy. 146 47

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.
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PMID:Adrenocorticotropin and cortisol responses to vasopressin during pregnancy. 164 36

To determine whether the adrenal androgen 11 beta-hydroxyandrostenedione is a more sensitive and specific marker than dehydroepiandrosterone sulfate, we compared these serum androgens in 81 women with anovulatory hyperandrogenism before treatment, after corticotropin and corticotropin-releasing-factor stimulation, and after short- and long-term dexamethasone suppression. Of all subjects, 65% and 57% had elevated levels of 11 beta-hydroxyandrostenedione (greater than 2.0 ng/ml) and dehydroepiandrosterone sulfate (greater than 2.8 micrograms/ml), respectively. However, 11 beta-hydroxyandrostenedione and dehydroepiandrosterone sulfate levels did not correlate in either the women with hyperandrogenism (r = 0.12) or the 26 normal women (r = 0.29). After 0.25 mg corticotropin was administered intravenously (n = 16), 11 beta-hydroxyandrostenedione increased by 157% +/- 53% (mean +/- SEM), whereas dehydroepiandrosterone sulfate, androstenedione, dehydroepiandrosterone, and cortisol increased by 6% +/- 2%, 46% +/- 10%, 416% +/- 80%, and 2326% +/- 371%, respectively. After intravenous administration of 100 micrograms corticotropin-releasing factor to eight patients, the percent change from baseline level to peak was 148% +/- 26%, 24% +/- 5%, 61% +/- 15%, 117% +/- 15%, and 116% +/- 18% for 11 beta-hydroxyandrostenedione, dehydroepiandrosterone sulfate, androstenedione, dehydroepiandrosterone, and cortisol, respectively. After 2 mg dexamethasone for 3 days (n = 10), 11 beta-hydroxyandrostenedione, dehydroepiandrosterone sulfate, androstenedione, and testosterone were suppressed by 95% +/- 2%, 74% +/- 3%, 51% +/- 9%, and 32% +/- 9%, respectively. Suppression with 0.5 mg dexamethasone for 3 months lowered 11 beta-hydroxyandrostenedione and dehydroepiandrosterone sulfate levels equally by 50% +/- 14% and 62% +/- 12%, respectively. 11 beta-Hydroxyandrostenedione is a useful marker of adrenal androgen secretion with a calculated sensitivity and specificity greater than that of dehydroepiandrosterone sulfate. The greater sensitivity of 11 beta-hydroxyandrostenedione over dehydroepiandrosterone sulfate to adrenal stimulation and suppression suggests its unique diagnostic use.
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PMID:Is 11 beta-hydroxyandrostenedione a better marker of adrenal androgen excess than dehydroepiandrosterone sulfate? 183 6

In a previous study we observed that calcitonin increases beta-endorphin, ACTH, and cortisol secretion. We assumed that calcitonin might have a modulatory role on the pituitary function. The present study was initiated to clarify whether this effect is due to a direct pituitary stimulation or to an indirect stimulation through CRF (corticotropin releasing factor). Fourteen healthy subjects, aged 30-60 years were investigated. All the subjects received 100 IU Salmon calcitonin Sandoz i.v. at 8 a.m. (time 0). Plasma beta-endorphin, ACTH and cortisol were estimated every 30 min from -30 to 120 min by specific radioimmunoassay. The same parameters were estimated a second time, at the same intervals, when cyproheptadine 8 mg (7 subjects) and 40 mg propranolol (7 subjects) were given per os at -30 min and calcitonin i.v. at time 0. beta-endorphin, ACTH and cortisol levels (Mean +/- SEM) rose significantly after calcitonin (peak value at 30-90 min) from 5.2 +/- 0.7 to 15.1 +/- 2.6 pmol/l; from 43.0 +/- 2.7 to 70.7 +/- 4.1 pg/ml and from 10.6 +/- 1.5 to 19.6 +/- 2.1 micrograms/100 ml respectively (p less than 0.0001 by analysis of variance and covariance and repeated measures). Propranolol 40 mg (per os) administered at time -30 did not alter the response of beta-endorphin, ACTH and cortisol to calcitonin (infused at time 0). Cyproheptadine, the antiserotonergic substance that inhibits the synthesis and release of CRF completely inhibited the stimulatory effect of calcitonin. We conclude that probably calcitonin has a modulatory role on the hypothalamo-pituitary adrenal axis and that it acts at the hypothalamic level probably by stimulating CRF secretion.
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PMID:Antiserotonergic inhibition of calcitonin-induced increase of beta-endorphin, ACTH, and cortisol secretion. 285 Mar 48

This study was designed to compare the responsiveness of adrenocorticotropin (ACTH) and cortisol secretion to corticotropin-releasing factor (CRF) in the morning and early evening in normal human subjects. Synthetic ovine CRF (1.0 micrograms/kg) or normal saline, was administered as an i.v. bolus injection to six normal males at 900 h and 1700 h. Blood samples were obtained before and 15, 30, 60, 90 and 120 min after CRF or saline injection. Significant increases in plasma ACTH and cortisol levels were observed in all subjects at the both time of testing after CRF injection. The net increments in the areas under the concentration curve (areas in the CRF experiment minus those in the saline control experiment) were not statistically different for both ACTH (mean +/- SEM: 41.0 +/- 10.6 pg/ml h in the morning: 51.1 +/- 8.9 pg/ml h in the evening) and cortisol (mean +/- SEM: 28.5 +/- 5.0 micrograms/dl h in the morning; 36.2 +/- 4.0 micrograms/dl h in the evening). Also no significant difference was observed in net increment, peak level and the ratio of peak level to the basal level of ACTH and cortisol after CRF injection. There were no appreciable changes in plasma concentrations of growth hormone, thyroid-stimulating hormone or prolactin, although slight but statistically significant rises in plasma levels of luteinizing hormone and follicle-stimulating hormone were observed. These results suggest that there is no significant difference in responsiveness of the pituitary-adrenal axis to CRF in the morning (900 h) and early evening (1700 h), and thus the time of day will not necessarily have to be considered when CRF is used between these times in a clinical test to evaluate pituitary ACTH reserve.
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PMID:Responses of plasma adrenocorticotropin and cortisol to intravenous injection of synthetic ovine corticotropin releasing factor in the morning and early evening in normal human subjects. 300 29

Corticotropin-releasing hormone (CRH) plays a key role in coordinating neuroendocrine, metabolic and behavioral responses in stress and affective disorders. To further investigate the effects of enhanced pituitary-adrenocortical activity upon sleep-related phenomena we administered four intravenous injections of 50 micrograms human (h)-CRH or saline to 11 normal males at 10 p.m., 11 p.m., 12 p.m. and 1 a.m. and measured plasma levels of cortisol and growth hormone (GH) as well as sleep EEG recordings throughout the night. Treatment with h-CRH resulted in a significant increase of mean (+/- SEM) cortisol secretion between 11 p.m. and 3 a.m. (h-CRH: 100.6 +/- 9.5 ng/ml; saline: 39.0 +/- 1.5 ng/ml; p less than 0.01). This initial cortisol increase after repeated h-CRH stimulations was followed by a period of attenuated plasma cortisol between 3 and 7 a.m. (h-CRH: 70.3 +/- 7.0 ng/ml; saline: 115.5 +/- 8.0 ng/ml; p less than 0.01). Cortisol surges after h-CRH were associated with a significant blunting of sleep-related GH release expressed as areas under concentration curves (h-CRH: 1.245 +/- 0.32 ng/ml/min.10(3); saline: 2.462 +/- 0.92 ng/ml/min.10(3), p less than 0.01). In addition to these hormonal effects, h-CRH induced a decrease of REM and slow wave sleep (stages III and IV) while the amount of more shallow sleep (stages I and II) increased. These effects upon sleep structure were more pronounced during the second part of the night.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of intravenous corticotropin-releasing hormone upon sleep-related growth hormone surge and sleep EEG in man. 326 35

Plasma immunoreactive CRF measured by radioimmunoassay decreased rapidly after intravenous injection of synthetic ovine corticotropin releasing factor (CRF) and showed a bi-exponential decay curve in five macaca fuscatas. Half lives of plasma immunoreactive CRF were 5.8 +/- 1.4 (Mean +/- SEM) min for the fast component and 38.3 +/- 2.4 min for the slow component. A bolus injection of 5 micrograms/kg CRF significantly increased the plasma cortisol level. CRF at 5 micrograms/kg induced a delayed response of ACTH and cortisol. Arginine vasopressin (AVP) at 0.5 micrograms/kg induced a slight increase in plasma ACTH and cortisol, but AVP at 0.1 micrograms/kg evoked no significant increase. When 0.5 micrograms/kg CRF and 0.1 micrograms/kg AVP were administered simultaneously, significant ACTH and cortisol responses occurred. The results indicate that CRF and AVP act synergistically to stimulate ACTH secretion in vivo.
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PMID:Synergistic interaction of corticotropin releasing factor and arginine vasopressin on adrenocorticotropin and cortisol secretion in Macaca fuscata. 608 20

The effects of progesterone or 17 alpha-hydroxyprogesterone on corticosterone regulation of beta-endorphin (beta-end) release have been studied in vitro using primary culture of rat anterior pituitaries. Incubation of pituitary cells with ovine corticotropin-releasing factor (CRF) for 2 h resulted in a dose-dependent increase in beta-end release. Maximal stimulation was obtained with 200 ng/ml CRF. Preincubation for 2 h with corticosterone resulted in a dose-dependent inhibition of CRF-induced beta-end release. When the cultures were preincubated for 2 h with 200 ng/ml corticosterone and increasing concentrations (1, 10, 100, 1,000, and 10,000 ng/ml) of progesterone, a significant decrease in the corticosterone feedback action was observed with 100 ng/ml progesterone. Complete inhibition of the action of 200 ng/ml corticosterone was achieved with 10,000 ng/ml progesterone. Moreover, when the cultures were preincubated with increasing concentrations of corticosterone in the presence of 100 ng/ml progesterone, the ED50 of corticosterone increased significantly from 212 +/- 36 to 940 +/- 42 ng/ml (mean +/- SEM; P less than 0.01). Under the same conditions, 17 alpha-hydroxyprogesterone had no effect. These data demonstrate that progesterone antagonizes the corticosterone feedback inhibition of beta-end release by rat anterior pituitary.
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PMID:Demonstration of an antiglucocorticoid action of progesterone on the corticosterone inhibition of beta-endorphin release by rat anterior pituitary in primary culture. 609 Jan 2

In a significant proportion of patients with acromegaly, a non-specific increase in plasma growth hormone (GH) has been recognized following administration of thyrotropin-releasing hormone (TRH) or luteinizing hormone-releasing hormone (LH-RH), probably due to the lack of the specificity of the receptor in their tumor cells. In this study, the effects of corticotropin-releasing factor (CRF), a newly isolated hypothalamic hormone, in addition to TRH and LH-RH, on plasma levels of GH and the other anterior pituitary hormones were evaluated in 6 patients with acromegaly. Synthetic ovine CRF (1.0 microgram/kg), TRH (500 micrograms) or LH-RH (100 micrograms) was given as an iv bolus injection, in the morning after an overnight fast. Blood specimens were taken before and after injection at intervals up to 120 min, and plasma GH, adrenocorticotropin (ACTH), thyrotropin, prolactin, luteinizing hormone, follicle-stimulating hormone and cortisol were assayed by radioimmunoassays. A non-specific rise in plasma GH was demonstrated following injection of TRH and LH-RH, in 5 of 6 and 2 of 5 patients, respectively. In all subjects, rapid rises were observed in both plasma ACTH (34.3 +/- 6.2 pg/ml at 0 min to 79.5 +/- 9.5 pg/ml at 30 min, mean +/- SEM) and cortisol level (9.1 +/- 1.3 micrograms/dl at 0 min to 23.4 +/- 1.2 micrograms/dl at 90 min). However, plasma levels of GH and the other anterior pituitary hormones did not change significantly after CRF injection. These results indicate that CRF specifically stimulates ACTH secretion and any non-specific response of GH to CRF appears to be an infrequent phenomenon in this disorder.
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PMID:Effect of synthetic ovine corticotropin-releasing factor on growth hormone secretion in patients with acromegaly. 609 67

Corticotropin-releasing factor [(CRF) 200 micrograms] was administered iv to five patients with classical pituitary-dependent Cushing's disease and to five normal subjects. In both groups no changes were observed in the plasma concentrations of hGH, PRL, TSH, LH, or FSH. In the normal subjects plasma ACTH levels rose from 41 +/- 9 (SEM) pg/ml to 87 +/- 28 pg/ml after 60 min (P less than 0.01) and plasma cortisol levels from 0.30 +/- 0.06 mumol/liter (8.0 +/- 0.2 micrograms/dl) to 0.53 +/- 0.07 mumol/liter (14.2 +/- 0.2 micrograms/dl) after 60 min (P less than 0.001). In the patients with classical Cushing's disease plasma ACTH levels increased from 109 +/- 23 to 281 +/- 78 pg/ml after 30 min (P less than 0.01) and plasma cortisol levels from 0.45 +/- 0.06 mumol/liter (12.0 +/- 0.2 micrograms/dl) to 1.02 +/- 0.21 mumol/liter (27.2 +/- 0.6 micrograms/dl) after 120 min (P less than 0.005). The absolute increments of ACTH and cortisol levels in the patients with Cushing's disease were significantly (P less than 0.02 and P less than 0.05, respectively) higher than in the normal subjects. In individual patients, however, CRF responses were rather variable; three of the patients had ACTH or cortisol increases within the mean +/- SD of the responses of the control subjects. In another patient with Cushing's disease due to bilateral macro- and micronodular adrenocortical hyperplasia, who had nonsuppressible circulating ACTH and cortisol levels, unresponsiveness to CRF was shown. These results indicate that testing the pituitary-adrenocortical axis of patients with Cushing's disease may reveal hyperresponsiveness, normal responsiveness, and even unresponsiveness.
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PMID:Responsiveness of the hypophyseal-adrenocortical axis to corticotropin-releasing factor in pituitary-dependent Cushing's disease. 630 29


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