Immunoreactive corticotropin-releasing hormone, adrenocorticotropin and cortisol in human plasma during pregnancy and delivery and postpartum

The activity of the hypothalamo-pituitary adrenal axis was examined, by measuring the levels of immunoreactive (IR) corticotropin-releasing hormone (CRH), adrenocorticotropin (ACTH) and cortisol (F) in human plasma during normal pregnancy and after delivery with or without complications and during normal postpartum using a specific RIA. The level of IR-CRH in maternal plasma increased progressively during pregnancy, increased further at delivery and declined rapidly to the non-pregnant level on the 1st day postpartum. The level of IR-F in maternal plasma also increased progressively during pregnancy, increased further at delivery, but decreased slowly postpartum, not returning to the non-pregnant level within 5 days. Significant correlations were found between the level of IR-CRH and IR-ACTH, IR-CRH and IR-F, and IR-ACTH and IRF in maternal plasma both during pregnancy and after delivery. It is noteworthy that the concentration of IR-CRH in the maternal plasma at delivery was higher in multiple pregnancy than in normal pregnancy, and that the level of IR-CRH in the umbilical cord in uncomplicated cases was much lower than that in the maternal plasma, and was significantly lower than those in the umbilical cord plasma in cases of asphyxia, IUGR or premature delivery. The level of IR-F, not IR-CRH and IR-ACTH, at normal vaginal delivery was significantly higher than that at elective cesarean section. On these results, we investigated the feto-maternal-hypothalamo-pituitary adrenal axis during pregnancy and delivery, in which CRH plays an important role.     

Beta-endorphin, adrenocorticotropic hormone, cortisol and catecholamines during aerobic and anaerobic exercise

Twelve non-specifically trained volunteers (aged 26.5 years, SD 3.6) performed exhausting incremental graded exercise (ST) and 1-min anaerobic cycle ergometer exercise (AnT) at 2-h intervals for the purpose of investigating beta-endorphin (beta-E) behaviour dependent on exercise intensity and anaerobic metabolism. In order to determine [beta-E], adrenocorticotropic hormone [ACTH], cortisol [C], adrenaline [A] and noradrenaline [NA] concentrations, venous blood samples were collected prior and subsequent to exercise until the 20th min of the recovery period, as well as in ST before and after exceeding the individual anaerobic threshold (THan,i). Before, during and after ST, lactate concentration, heart rate and perceived degree of exertion were also determined; after AnT maximum lactate concentration was measured. Both types of exercise led to significant increases in [beta-E], [ACTH], [A] and [NA], with levels of [beta-E] and [ACTH] approximately twice as high after ST as after AnT. The [C] increased significantly only after ST. During ST significant changes in [beta-E] and [ACTH] were measured only after exceeding THan,i. At all measuring times before and after ST and AnT both hormones correlated positively. In AnT the increases of [beta-E] and [A] demonstrated a correlation (r = 0.65; P less than 0.05). Both in AnT and ST there was a relationship between the maximum concentrations of beta-E and lactate (r = 0.63 and 0.71; each P less than 0.05). We therefore conclude that physical exercise with increasing or mostly anaerobic components leads to an increase in [beta-E], the extent correlating with the degree of lactate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ovine corticotropin-releasing hormone stimulation test in patients with chronic renal failure: pharmacokinetic properties, and plasma adrenocorticotropic hormone and serum cortisol responses

The data on the status of the hypothalamic-pituitary-adrenal (HPA) axis in haemodialysis (HD) patients are conflicting. Moreover, a state reminiscent of Cushing's syndrome has been reported in this group of patients. Corticotropin-releasing hormone (CRH), that is produced by the hypothalamus and modulates the secretion of adrenocorticotropic hormone (ACTH), has been shown to be useful as a provocative test of the HPA axis. We investigated the effect of exogenous ovine CRH (oCRH) on plasma levels of ACTH and cortisol in 13 chronic HD patients. The plasma concentrations of immunoreactive CRH following oCRH administration were similar in patients and controls. In all patients, oCRH given intravenously as bolus injection caused a further increase in the already elevated levels of cortisol. The mean basal plasma levels of ACTH were within the normal range. There was, however, a blunted ACTH response to oCRH. We conclude that the HPA axis in chronic HD patients retains the ability to respond to exogenous oCRH. The patterns of the ACTH and cortisol response to this peptide resemble those observed in chronic stress (depression, anorexia nervosa). Besides, the kinetics of disappearance of oCRH indicate that the kidney may not be the major organ that metabolizes oCRH.     

Maternal corticotropin-releasing hormone levels during pregnancy and offspring adiposity

Objective: Animal models suggest that fetal exposure to glucocorticoids can program adiposity, especially central adiposity, later in life. We examined associations of maternal corticotropin‐releasing hormone (CRH) levels in the late 2nd trimester of pregnancy, a marker of fetal glucocorticoid exposure, with child adiposity at age 3 years. Research Methods and Procedures: We analyzed data from 199 participants in Project Viva, a prospective cohort study of pregnant women and their children, At age 3 years, the main outcomes were age‐sex‐specific BMI z score and the sum of subscapular (SS) and triceps (TR) skinfold thicknesses to represent overall adiposity, and ratio of SS to TR (SS:TR) to represent central adiposity. Results: Mean (standard deviation) maternal 2nd trimester log CRH was 4.94 (0.56) pg/mL. At age 3, mean (standard deviation) for BMI z score was 0.52 (1.02); for SS + TR, 16.51 (3.94) mm; and for SS:TR, 0.67 (0.17). Log CRH was mildly inversely correlated with birth weight (r = ?0.08), chiefly because of its association with length of gestation (r = ?0.21) rather than fetal growth (r = ?0.004). After adjustment for sociodemographic factors, maternal smoking, BMI, and gestational weight gain, fetal growth, length of gestation, breastfeeding duration, and (for SS:TR only) child's 3‐year BMI, each increment of 1 unit of log CRH was associated with a reduction in BMI z score [?0.43; 95% confidence interval (CI), ?0.73, ?0.14; p = 0.004] and possible reduction in SS + TR (?1.10; 95% CI, ?2.33, 0.14; p = 0.08). In contrast, log CRH was associated with higher SS:TR (0.07; 95% CI, 0.02, 0.13; p = 0.007). Discussion: Fetal exposure to glucocorticoids, although associated with an overall decrease in body size, may cause an increase in central adiposity.     

Attenuation of corticotropin-releasing hormone and arginine vasopressin responsiveness during late-gestation pregnancy in sheep

Responsiveness of the hypothalamo-pituitary-adrenal axis is decreased during pregnancy. Therefore, the objective of the present study was to determine if responsiveness at the level of individual corticotrophs to corticotropin-releasing hormone (CRH) or arginine vasopressin (AVP) is decreased during pregnancy in sheep. Anterior pituitaries (APs) were collected from pregnant and nonpregnant ewes. Half of the APs were dispersed, and cells were placed on immobilon and treated with vehicle, CRH (10 nM), or AVP (100 nM) for 2 h. Cells were then fixed and incubated with ACTH or pro-opiomelanocortin (POMC) antibodies. The percentage of cells staining positive for immunoreactive (ir) ACTH or POMC, the percentage of cells secreting irACTH or POMC, and the area of irACTH or POMC secretion were measured. RNA was extracted from the other half of the APs to quantify CRH type 1 (CRH-R1) and vasopressin type 1b (V1b) receptor mRNA by ribonuclease protection assay. CRH treatment increased the percentage of corticotrophs with relatively large areas of irACTH and POMC secretion in nonpregnant, but not in pregnant, ewes. AVP treatment significantly increased the percentage of irACTH- and POMC-secreting cells in nonpregnant, but not in pregnant, ewes. V1b receptor mRNA, but not CRH-R1 receptor mRNA, was significantly decreased during pregnancy. These results suggest that corticotroph responsiveness to CRH and AVP is decreased during pregnancy in sheep. Therefore, reduced corticotroph responsiveness may contribute to stress hyporesponsivity during pregnancy.     

Effect of cortisol or adrenocorticotropic hormone on luteinizing hormone secretion by pig pituitary cells in vitro

The effect of cortisol or adrenocorticotropic hormone (ACTH) on basal and gonadotropin-releasing hormone (GnRH)-induced secretion of luteinizing hormone (LH) was studied in vitro using dispersed pig pituitary cells. Pig pituitary cells were dispersed with collagenase and DNAase and then grown in McCoy's 5a medium containing 10% dextran charcoal-pretreated horse serum and 2.5% fetal calf serum for 3 days. Cells were preincubated with cortisol or ACTH before GnRH was added. When pituitary cells were incubated with 400 micrograms cortisol/ml medium for 6 h or longer, increase basal secretion of LH was observed. However, GnRH-induced LH release was reduced by cortisol. The degree of this reduction was dependent on cortisol, and a concentration of cortisol higher than 100 micrograms/ml was needed. Cortisol also inhibited the 17 beta-estradiol-induced increase in GnRH response. ACTH-(1-24), ACTH-(1-39), or porcine ACTH had no influence on GnRH-induced LH secretion. Our results show that cortisol can act directly on pig pituitary to inhibit both normal and estradiol-sensitized LH responsiveness to GnRH.     

The inhibitory action of corticotropin-releasing hormone on gonadotropin secretion in the ovariectomized rhesus monkey is not mediated by adrenocorticotropic hormone

Earlier observations in our laboratory indicated that i.v. infusion of human/rat corticotropin-releasing hormone (hCRH) suppresses pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release in ovariectomized rhesus monkeys. Since cortisol secretion increased significantly as well, it was not possible to exclude the possibility that this inhibitory effect of hCRH on gonadotropins was related to the activation of the pituitary/adrenal axis. The purpose of the present study was to determine the role of pituitary/adrenal activation in the effect of hCRH on LH and FSH secretion. We compared the effects of 5-h i.v. infusions of hCRH (100 micrograms/h, n = 7) and of human adrenocorticotropic hormone (ACTH) (1-24) (5 micrograms/h, n = 3; 10 micrograms/h, n = 3, 20 micrograms/h, n = 3) to ovariectomized monkeys on LH, FSH, and cortisol secretion. As expected, during the 5-h ACTH infusions, cortisol levels increased by 176-215% of baseline control, an increase similar to that observed after CRH infusion (184%). However, in contrast to the inhibitory effect observed during the CRH infusion, LH and FSH continued to be released in a pulsatile fashion during the ACTH infusions, and no decreases in gonadotropin secretion were observed. The results indicated that increases in ACTH and cortisol did not affect LH and FSH secretion and allowed us to conclude that the rapid inhibitory effect of CRH on LH and FSH pulsatile release was not mediated by activation of the pituitary/adrenal axis.     

Atrial natriuretic peptide does not affect corticotropin-releasing factor-, arginine vasopressin- and angiotensin II-induced adrenocorticotropic hormone release in vivo or in vitro

The effect of synthetic atrial natriuretic peptide (ANP) was examined on the in vivo and in vitro release of ACTH. Intravenous ANP (4 micrograms/kg body weight) administration did not affect the corticotropin releasing factor (CRF, 4 micrograms/kg body weight)-, arginine vasopressin (AVP, 2 micrograms/kg body weight)- and angiotensin II (A II, 4 micrograms/kg body weight)-induced ACTH release in unanesthetized freely moving rats. ANP did not inhibit the basal, CRF- and AVP-induced release of ACTH in pituitary cell cultures. ANP did not affect the CRF- and AVP-induced plasma corticosterone elevation, while it attenuated the AVP-induced corticosterone elevation. These results indicate that ANP does not affect the ACTH release at the pituitary level in vivo and in vitro.     

Pattern of maternal serum corticotropin-releasing hormone concentration during pregnancy in the common marmoset (Callithrix jacchus)

Corticotropin-releasing hormone (CRH), a potent neuropeptide, is produced by the placenta of anthropoid primates. No other mammals, including prosimian primates, are known to produce placental CRH. In humans, placental CRH appears to play an important role in the progression of pregnancy to parturition. Maternal circulating CRH begins to rise early in pregnancy and increases until parturition. Gorillas and chimpanzees share this pattern of increasing maternal CRH during pregnancy with humans. In humans, chimpanzees, and gorillas, maternal CRH and estradiol concentrations are correlated, consistent with the hypothesis that CRH is involved in the biosynthetic pathway for placental estrogen production. In contrast, in baboons, maternal circulating CRH rises precipitously early in pregnancy and then declines, though CRH is detectable until birth. This research was designed to investigate the pattern of maternal circulating CRH in the common marmoset during pregnancy. Blood samples were taken across gestation from nine subjects over 11 pregnancies, and the plasma was assayed for CRH. The pattern of maternal circulating CRH in the common marmoset was similar to that of the baboon, with a rapid rise starting at about 50 days postconception and a peak at approximately 70 days postconception. By 110 days postconception, CRH concentration had plateaued at a significantly lower value. The peak and mean values for CRH were associated with fetal number (e.g., females gestating triplets had higher values than females gestating twins). Urinary estradiol showed no association with plasma CRH concentration. Marmosets appear to differ from the great apes in this regard, and to share a pattern of maternal CRH during pregnancy with the baboon, indicating that the baboon and marmoset pattern may be ancestral. The function of the early rapid rise of CRH in baboons and marmosets, and the significance of this difference between monkeys and apes, are not known.     

Plasma adrenocorticotropic hormone and cortisol in pigs: effects of time of day on basal and stressor-altered concentrations

An initial study was conducted to establish the presence in plasma of diurnal rhythms of immunoreactive porcine adrenocorticotropic hormone (pACTH) and cortisol in castrated male pigs (barrows). Fourteen barrows with jugular catheters were bled at 6-hr intervals for 24 hr. Significant changes in plasma pACTH were evident with peak levels (61 +/- 6 pg/ml) at 0100-0700 hr and a trough (38 +/- 4 pg/ml) at 1900 hr. Changes (P less than 0.05) in plasma cortisol were also present in barrows with a peak (44 +/- 6 ng/ml) at 0700 hr and a trough (21 +/- 5 ng/ml) at 1900 hr. Plasma norepinephrine and epinephrine were measured at the same time intervals and did not differ among hours. In these unstressed pigs the ratio cortisol/log10pACTH at 0700 hr (25.3 +/- 3.0) was greater than the ratio at 1900 hr (12.9 +/- 2.7). Sequential blood samples were subsequently taken on four of the barrows 12 and 26 days later. Plasma pACTH was variable among pigs and did not differ among hours. Plasma cortisol on both dates was greater (P less than 0.05) in the morning (0100 or 0700 hr) than at 1900 hr. The ratio cortisol/log10pACTH at 0700 hr was repeatedly greater than at 1900 hr. A second study was conducted to determine whether plasma pACTH and cortisol responses to mild (32 degrees C for 2 hr) or strong (20-min restraint) stressors were dependent on the time of day of stressor application (0800 hr, AM; 1600 hr, PM). Response-associated parameters (maximum concentration, maximum incremental concentration, and integrated response) for pACTH and cortisol did not differ between AM and PM. However, a qualitative difference existed between the AM and PM plasma pACTH responses to restraint +32 degrees C wherein the AM response consisted of a single prolonged surge, and the PM response of an initial major peak followed by a second significant minor peak. A suggested explanation is that the initial 20-min restraint stressor potentiated the hypothalamic-hypophyseal response to 32 degrees C. These studies are the first direct measurements which suggest the presence of diurnal changes in plasma ACTH and cortisol in barrows. The studies also indicate for barrows an absence of diurnal changes in plasma epinephrine and norepinephrine. The responsiveness of the pituitary-adrenocortical axis to stressors did not exhibit quantitative diurnal changes at the time periods measured. However, it is hypothesized that the repeatable AM-PM difference in the ratio cortisol/log10ACTH reflects a diurnal change in adrenal responsiveness to ACTH in unstressed pigs.     

Presence of immunoreactive corticotropin-releasing hormone and cortisol molecules in invertebrate haemocytes and lower and higher vertebrate thymus

Corticotropin-releasing hormone- and cortisol-like molecules are present in the haemocytes of different molluscan species and in the epithelial cells, interdigitating cells and macrophages -- but not in the lymphocytes -- of fish, frog, chicken and rat thymus. Taking into account the fact that other pro-opiomelanocortin-derived peptides, such as adrenocorticotropin hormone, are present in the haemocytes and thymus of the same species, these results complete the list of stress mediators present in molluscan haemocytes and further support the hypothesis that, although the prototype stress response we have demonstrated in invertebrates is concentrated in a single cell, i.e. the haemocyte, it is similar to the response seen in vertebrates. Moreover, the data presented here are compatible with the hypothesis that an evolutionary, conserved stress response can occur locally with a single organ, e.g. the thymus, in which all the main mediators of this biological response, such as corticotropin-releasing hormone, adrenocor ticotropin hormone and glucocorticoids, are present. The implications of these findings for the physiology of thymus and stress response may be far reaching. © 1998 Chapman & Hall     

Repeated administrations of adrenocorticotropic hormone during late gestation in pigs: maternal cortisol response and effects on fetal HPA axis and brain neurotransmitter systems

The present study examined the effects of repeated adrenocorticotropic hormone (ACTH) administrations to sows during late gestation on hypothalamic-pituitary-adrenocortical (HPA) axis and brain neurotransmitter systems in their fetuses. ACTH (100 IU per animal, Synacthen Depot, n=6) or saline (n=5) was administered intramuscularly to sows every 2nd day from gestational day (GD) 85 to GD 101. Blood samples were taken from sows repeatedly within 12h after ACTH application on GD 85 and GD 101. On GD 105, fetuses were recovered under general anaesthesia for the collection of blood and brain samples. Plasma cortisol concentrations in sows increased significantly within 2h after ACTH application and returned to control levels after 10h post-application, showing a similar response at the beginning and at the end of the 16-day stimulation period. On GD 101, a significant increase of plasma glucose and insulin concentrations was found in sows after administration of ACTH and after a following feeding time. Number and body weight of fetuses were not affected by the maternal ACTH treatment. Cortisol concentrations in the umbilical vein were significantly decreased in fetuses from ACTH sows and a similar trend was observed in the umbilical artery and in the vena cava cranialis. Glucocorticoid receptor (GR) binding in hippocampus and hypothalamus did not differ between treatments. However, in hippocampus, serotonergic activity was increased in fetuses from ACTH-treated mothers as shown by significantly elevated 5-hydroxytryptamine (5-HT) levels. In conclusion, repeated administrations of ACTH during late gestation resulted in a reproducible cortisol response of sows and reduced cortisol concentrations in the fetal umbilical vein after the treatment period. Although the number of sows used in this experiment was low and differences between treatments were limited these findings indicate that excessive glucocorticoid exposure during gestation alters serotonergic activity in hippocampus of fetuses and may affect the emotional reactivity later in life.     

In vivo and in vitro studies on the effect of adrenocorticotropic hormone or cortisol on the pituitary response to gonadotropin releasing hormone

Experiment I: Hyperadrenal states were induced in intact heifers (N = 3) or adrenalectomized (ADRX) heifers (N = 3) by constant infusion of ACTH (20.8 micrograms, 1-24 ACTH/h) or hydrocortisone succinate (HS) (30 mg/h), respectively. Control infusions consisted of the saline vehicle. All infusions began on Day 2 of a normal estrous cycle. Exogenous gonadotropin releasing hormone (GnRH) was given as a 100-micrograms bolus i.v. on Days 7, 9, and 11 (intact) or 5, 7, and 9 (ADRX) of the cycle. In intact heifers, the cumulative luteinizing hormone (LH) response was reduced (P less than 0.05) by the ACTH treatment. In ADRX heifers, the HS treatment did not alter the cumulative response but did alter the qualitative response with a time X treatment interaction (P less than 0.01). The LH response in the HS-ADRX animals had a slower onset and lower peak concentrations with a more prolonged response. Experiment II: Dispersed bovine pituitary cells were prepared and incubated at concentrations of 2 X 10(6) viable cells in 2.0 ml per dish. Cells were exposed to cortisol at concentrations of 0.01, 0.10, 0.21 and 1.03 X 10(-6) M for time periods of 8, 14, 20 or 26 h for basal LH secretion studies and 10, 16, 22 and 28 h for GnRH-stimulated LH secretion. Both dosage of cortisol and length of exposure had a depressing effect on basal LH release. The cortisol pretreatment also decreased (P less than 0.001) the LH release following addition of GnRH (8.5 X 10(-8) M) in cultures at all dosages and exposure times of cortisol. However, there was no decrease in LH or protein content of cells. These experiments indicate a direct action of cortisol on the pituitary gland to depress both basal and stimulated LH release.     

Effects of leptin on fetal plasma adrenocorticotropic hormone and cortisol concentrations and the timing of parturition in the sheep

We investigated whether leptin can suppress the prepartum activation of the fetal hypothalamus-pituitary-adrenal (HPA) axis and delay the timing of parturition in the sheep. First, we investigated the effects of a 4-day intravascular infusion of recombinant ovine leptin (n = 7) or saline (n = 6) on fetal plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations, starting from 136 days gestation (i.e., at the onset of the prepartum activation of the fetal HPA axis. The effects of a continuous intrafetal infusion of leptin (n = 7) or saline (n = 5) from 144 days gestation on fetal plasma ACTH and cortisol concentrations and the timing of delivery were also determined in a separate study. There was an increase in fetal plasma ACTH (P < 0.01) and cortisol (P < 0.001) concentrations when saline was infused between 136-137 and 140-141 days gestation. Plasma ACTH and cortisol concentrations did not rise, however, when leptin was infused during this period of gestation. When leptin was infused after 144 days gestation, there was no effect of a 4- to 5-fold increase in circulating leptin on fetal ACTH concentrations. In contrast, leptin infusion from 144 days gestation suppressed (P < 0.05) fetal plasma cortisol concentrations by around 40% between 90 and 42 h before delivery. There was no difference, however, in the length of gestation between the saline- and leptin-infused groups (saline infused, 150.2 +/- 0.5 days; leptin infused, 149.8 +/- 1.0 days). In saline-infused fetuses, there was a significant negative relationship between the plasma concentrations of cortisol (y) and leptin (x) between 138 and 146 days gestation (y = 81.4 - 7.7x, r = 0.38, P < 0.005). This study provides evidence for an endocrine negative feedback loop between leptin and the HPA axis in fetal life.     

Cortisol, adrenocorticotropic hormone and apolipoprotein synthesis in rat hepatocytes]

The influence of cortisol (5 mg/kg body wt administered daily for 5 and 10 days) on biosynthesis of apoproteins of lipoproteins of very low density in the liver and on the synthesis of apolipoproteins of very low, low, and high density (VLDL, LDL, and HDL apoproteins, respectively) in the blood serum of adrenalectomized animals, and after replacement cortisol therapy was studied. Cortisol treatment during these periods resulted in the VLDL apoproteins biosynthesis inhibition in the rat liver. The synthesis of apolipoproteins was increased by adrenalectomy; this effect was eliminated after replacement cortisol treatment. The apoprotein synthesis was stimulated within 5 hours by single injection of cortisol or ACTH. Study of the blood serum apolipoproteins specific radioactivity indicated metabolic change of lipoproteins, such as disturbed conversion from VLDL to LDL. Single and prolonged cortisol administration led to the opposite results. The authors believe that the metabolic disturbances of lipoproteins in the blood play a more important role in the pathogenesis of cortisol-induced hyperlipidemia than lipoprotein syntesis stimulation in the liver.     

Effects of corticotropin-releasing factor, corticotropin and cortisol on gastrointestinal motility in dogs

Gastrointestinal motor activity following intracerebroventricular (ICV) and intravenous (IV) administration of corticotropin releasing factor (CRF), corticotropin (ACTH) and cortisol was investigated in fasted dogs with strain-gauge transducers chronically implanted on the antrum and proximal jejunum. ICV but not IV administration of CRF (20 to 100 ng/kg) suppressed the gastric cyclic migrating motor complex (MMC) for 3 to 6 hours without affecting the jejunum. Similar disruptive effects on the gastric MMC were observed after ICV administration of ACTH (0.5 U/kg) or cortisol (0.1 micrograms/kg) but not after IV administration of 10 times higher doses. These results suggest that in dog CRF may be involved in the central control of the interdigestive gastric motility, these effects were not probably due to the release of ACTH and cortisol the other hormones of the pituitary adrenocortical system change the gastric motility when centrally administered through a possible feed-back mechanism affecting brain CRF level.     

Biosynthesis and characterization of adrenocorticotropic hormone, alpha-melanocyte-stimulating hormone, and an NH2-terminal fragment of the adrenocorticotropic hormone/beta-lipotropin precursor from rat pars intermedia.

Isolated intermediate lobe cells from 40 rat pituitaries were incubated for 3 h with [35S]methionine + [3H]-phenylalanine, [35S]methionine, [3H]valine, and [3H]leucine. The cell extracts were purified by carboxymethyl-cellulose chromatography (CMC) and the fraction eluting with ovine adrenocorticotropic hormone (ACTH) was further purified either by another CMC under the same conditions or by high performance liquid chromatography (HPLC). Microsequencing of the product from the second CMC allowed the identification of a peptide containing methionine 4 and phenylalanine 7, as expected for the NH2 terminus of ACTH. Purification by HPLC of a similar peptide obtained from the three other incubations gave three main raoactive peaks which were further characterized by their migration rates on polyacrylamide gels, molecular weight, and microsequencing. Results indicated that intact ACTH (residues 1-39) is present in extracts of rat intermediate lobe, but in very small quantities (less than 1% of the beta-endorphin content). ACTH is probably broken down into smaller fragments, e.g. alpha-melanocyte-stimulating hormone (alpha-MSH) (ACTH, 1-13) and corticotropin-like intermediate lobe peptide (CLIP) (ACTH, 18-39). These studies also revealed with existence of a peptide having identical sequence with the (N-1) terminus of the ACTH/lipotropin (LPH) precursor.     

Plasma levels of adrenocorticotropic hormone and cortisol in people living in an environment below sea level (Jordan Valley) during fasting in the month of Ramadan

OBJECTIVES: To investigate the effects of Ramadan fasting on plasma levels of ACTH and cortisol in athletic students living in the Jordan Valley (JV) and compare them to those living at above sea level in Ramtha City (RC). METHODS: Sample collection and measurements were done in November 1998 from non-fasting and in December 1998 from fasting people. RESULTS: ACTH levels in non-fasting subjects in the JV were 36 +/- 4 IU/ml compared to 43 +/- 3 IU/ml for those in RC. Cortisol levels were 483 +/- 76 (JV) and 539 +/- 89 nmol/l (RC). Fasting led to an increase in ACTH (49 +/- 6 (JV) and 58 +/- 5 IU/ml (RC)) and cortisol levels (637 +/- 101 (JV) and 805 +/- 72 nmol/l (RC)). CONCLUSION: Fasting increases ACTH and cortisol levels in an altitude-independent fashion.