Periconceptional undernutrition in sheep accelerates maturation of the fetal hypothalamic-pituitary-adrenal axis in late gestation

We investigated the effects of moderate maternal periconceptional undernutrition from 60 d before to 30 d after mating on fetal hypothalamic-pituitary-adrenal axis function in late gestation. Ewes were sampled regularly during the period of undernutrition for circulating hormone levels. Vascular catheters were inserted into ewes and their singleton fetuses at 112 d gestation (term, 145 d), and fetal ACTH(1-24) and metyrapone challenge tests were performed at 127 and 128 d. Postmortems were performed at 132 d. Fetuses of undernourished ewes (UN, n = 12) had elevated baseline cortisol concentrations (P < 0.05), compared with fetuses of ad libitum-fed ewes (n = 10). There were no differences between groups in fetal responses to ACTH challenge, but only UN fetuses demonstrated ACTH and 11-deoxycortisol responses to metyrapone (P < 0.05). UN fetuses had increased mRNA levels for proopiomelanocortin and prohormone convertase-1, but not -2, in the pars intermedia of the pituitary gland (P < 0.05). Glucocorticoid receptor mRNA levels were not different between groups in pituitary or hypothalamus. Maternal cortisol and ACTH levels during undernutrition were profoundly suppressed (P < 0.001), rather than elevated, in UN ewes. Furthermore, the normal pregnancy rise in maternal serum progesterone concentrations was delayed in undernourished mothers. These data demonstrate that events around the time of conception have profound effects on fetal hypothalamic-pituitary-adrenal development in late gestation and that factors other than fetal exposure to excess glucocorticoids may be important.     

Allopregnanolone in the brain and blood after disruption of the hypothalamic-pituitary-adrenal axis in fetal sheep

Neuroactive steroids may be synthesised in the brain either de novo from cholesterol or from blood-borne precursors. Concentrations of a GABAA receptor agonist, allopregnanolone, in the fetal brain exceed those in the circulation, and are markedly higher than adult brain concentrations. We used fetal hypophysectomy or adrenalectomy to elucidate the contribution of hypothalamic-pituitary factors and adrenal steroid secretion to the overall neuroactive steroid level in both the fetal brain and the fetal circulation. Hypophysectomy or adrenalectomy was performed between 108 and 112 days of gestation (term approximately 147 days) and fetal tissues were collected at 140 days of gestation. Immunoreactive (ir) ACTH and cortisol in the plasma were significantly reduced after hypophysectomy, whereas adrenalectomy led to increased irACTH but significantly decreased cortisol concentrations, as expected. Brain concentrations of allopregnanolone, progesterone and pregnenolone did not change significantly in fetuses that underwent either hypophysectomy or adrenalectomy; however, concentrations in the plasma and content in the adrenal gland were decreased. Expression of cytochrome P450 scc and 5alpha-reductase type II (5alphaRII) in the brain, measured by western immunoblotting, did not change after either hypophysectomy or adrenalectomy but, after hypophysectomy, expression of P450 scc in the adrenal gland was significantly decreased and that of 5alphaRII remained unchanged. These findings suggest that the regulation of the neuroactive steroid content in the fetal brain is independent of adrenal steroidogenesis and hypothalamic-pituitary factors. Furthermore, the absence of a change in enzyme expression in the brain suggests that the control of the expression of these enzymes is independent of hypothalamic-pituitary factors. Thus local control mechanisms within the brain may be responsible for maintaining the high neurosteroid content present during fetal life, as these mechanisms are independent of adrenal steroid production.     

增食欲素调节下丘脑-垂体-肾上腺轴的研究进展

增食欲素A和增食欲素B是下丘脑神经肽,通过激活两种G蛋白耦联受体发挥作用.增食欲素及其受体表达于下丘脑室旁核和正中隆起,增食欲素受体还表达于脑垂体促皮质激素细胞、肾上腺皮质和髓质.增食欲素能调节摄食、能量代谢平衡、睡醒周期、血压等,还能调节下丘脑-垂体-肾上腺(HPA)轴.现就增食欲素及其受体在HPA轴中枢支和周围支(peripheral branches)的表达及作用机制作一综述.     

增食欲素调节下丘脑-垂体-肾上腺轴的研究进展

增食欲素A和增食欲素B是下丘脑神经肽,通过激活两种G蛋白耦联受体发挥作用.增食欲素及其受体表达于下丘脑室旁核和正中隆起,增食欲素受体还表达于脑垂体促皮质激素细胞、肾上腺皮质和髓质.增食欲素能调节摄食、能量代谢平衡、睡醒周期、血压等,还能调节下丘脑-垂体-肾上腺(HPA)轴.现就增食欲素及其受体在HPA轴中枢支和周围支(peripheral branches)的表达及作用机制作一综述.     

增食欲素调节下丘脑-垂体-肾上腺轴的研究进展

增食欲素A和增食欲素B是下丘脑神经肽,通过激活两种G蛋白耦联受体发挥作用.增食欲素及其受体表达于下丘脑室旁核和正中隆起,增食欲素受体还表达于脑垂体促皮质激素细胞、肾上腺皮质和髓质.增食欲素能调节摄食、能量代谢平衡、睡醒周期、血压等,还能调节下丘脑-垂体-肾上腺(HPA)轴.现就增食欲素及其受体在HPA轴中枢支和周围支(peripheral branches)的表达及作用机制作一综述.     

Brief undernutrition in late-gestation sheep programs the hypothalamic-pituitary-adrenal axis in adult offspring

Reduced size at birth in humans has been associated with altered function of the hypothalamic-pituitary-adrenal (HPA) axis in childhood and adult life. Experimentally, maternal undernutrition has also been associated with altered fetal HPA function. However, the relationship between birth size, fetal nutrition, and adult pathophysiology is not clear. We recently have reported that glucose tolerance, blood pressure, and IGF-I levels in adult sheep were more closely associated with birth weight than with nutritional insult in late gestation or with current weight. Here, we report adult HPA function in the same group of animals. Pregnant ewes were severely undernourished for 10 d (UN10) or 20 d (UN20) from 105 d gestation (term, 146 d), or were ad libitum-fed controls. At 30 months, female offspring were subjected to an insulin tolerance test and a CRH plus arginine vasopressin (AVP) challenge. UN20 lambs were lighter at birth, but there were no significant differences in weight at 30 months. Adult UN10 ewes had an increased ACTH response to both CRH+AVP challenge and insulin tolerance test, but no differences in cortisol response. UN10 ewes also demonstrated elevated 11-deoxycortisol concentrations, but lower progesterone concentrations, in response to CRH+AVP challenge. In contrast, the responses of UN20 ewes to these challenges were not different from ad libitum controls. Protein levels of P450(c17) and P450(11beta1) were not significantly different among groups. We conclude that brief maternal undernutrition for 10 d, but not 20 d, in late gestation alters HPA function in adult offspring. In contrast to our previous findings, these HPA effects are independent of birth weight and current weight, suggesting that different mechanisms may be involved in programming different physiological axes.     

Regulation of the hypothalamo-pituitary-adrenocortical axis in fetal sheep.

Development of the fetal hypothalamo-pituitary-adrenal (HPA) axis is required for normal fetal life and subsequent neonatal health. Activation of the fetal pituitary gland results in the synthesis and release of glucocorticoids from the adrenal cortex. Glucocorticoids promote maturation of several organ systems, are important in responses of the fetus to stress, and are involved in the initiation of parturition in several species. The expression of hypothalamic and pituitary genes associated with HPA function is apparent early in gestation in fetal sheep, although the endocrine changes associated with maturation and parturition do not occur until the last fifth of gestation. In this connection, the fetal HPA axis can be activated by treatment with hypophysiotrophic factors or moderate stress throughout gestation. This review focuses on the development of neuroendocrine mechanisms controlling HPA function during fetal life.     

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

BACKGROUND Abnormal baseline hypothalamic-pituitary-adrenal axis function and dexamethasone suppressibility seen in withdrawing alcoholics returns to normal on abstinence, but some studies report blunting of the ACTH response to CRH persisting during the early abstinence phase. Reduced central levels of endogenous oplold peptides have been postulated to have an aetiological role In alcohol addiction. AIMS To evaluate hypothalamic-pituitary-adrenal axis function in a group of recently abstinent alcoholics using basal hormone data, naloxone (an oplold receptor antagonist), and ovine CRH. SUBJECTS Nine alcoholics (age 41.4±3.1 years) studied more than one week after the acute withdrawal period but within 6 weeks of cessation of drinking, and nine age and sex matched non-alcoholic controls. PROTOCOL Cortisol, ACTH, CRH and AVP levels were measured every 20 minutes for 2 hours between 0900 and 1100h. Twenty mg naloxone I.v. was administered at 1100h (0 minutes) and further samples for the above hormones were taken at 15, 30, 45, 60, 90 and 120 minutes. On a separate occasion, again at 1100h, oCRH 1μg/kg (n= 7 alcoholics, n = 6 controls) was administered, with samples for cortisol, ACTH and AVP taken at the same times. STATISTICS Results were examined by analysis of variance for repeated measures (ANOVA), while Incremental hormone response and area under the secretory curve (AUC) in alcoholics versus controls were compared by the two-tailed Student's t-test. Linear regression analysis was carried out to examine the relation between basal cortisol and hormone responses to naloxone and oCRH. RESULTS Basal hormone levels did not differ between the groups. The alcoholics had a blunted ACTH incremental response to naloxone (11.4±3.0 vs 21.1±25 pmol/l, P< 0.05) but the cortisol response was not signiflcantly different (205±51 vs 305±42 nmol/l, P= 0.15). The alcoholics also had a blunted ACTH incremental response to oCRH (28.7 ± 4.2 vs 41.2 ± 3.7 pmol/l, P= 0.052) and by ANOVA a significant main effect of group (alcoholic vs control) was seen (P < 0.02) for the ACTH response to oCRH. There was no difference between the groups in the cortisol Incremental response to oCRH. In the control subjects, a negative correlation was found between basal cortisol and the cortisol Increment (r=-0.82, P< 0.05) and ACTH Increment (r=-0.81, P = 0.052) following oCRH, while In contrast, basal cortisol correlated positively with cortisol increment (r= 0.72, P < 0.05) following naloxone. There was also a trend for basal cortisol to correlate positively with ACTH increment following naloxone In the controls (r= 0.63, P < 007). In the alcoholics, the normal negative effect of basal cortisol on the cortisol Increment after oCRH was reversed, with a positive correlation between basal cortisol and cortisol increment (r= 0.75, P= 0.05). CONCLUSIONS Recently abstinent alcoholics with normal basal HPA axis hormone levels have a blunted ACTH response to naloxone and oCRH. While reduced levels of central endogenous oplold peptides may be a factor in the blunted ACTH response to naloxone In the alcoholics, it Is proposed that the alcoholics have reduced pituitary responsiveness to CRH. This may be via a direct pituitary effect of the chronic ethanol exposure or by a reduction in hypothalamic-hypophyseal vasopressin levels.     

Effect of maternal nutrient restriction in early gestation on development of the hypothalamic-pituitary-adrenal axis in fetal sheep at 0.8-0.9 of gestation

The fetal hypothalamic-pituitary-adrenal (HPA) axis has numerous key roles in development. Epidemiological data have linked adverse prenatal nutrition with altered organ development and increased incidence of disease in adult life. We studied HPA axis development in resting and stimulated states in late gestation fetal sheep, following 15% reduction in maternal nutritional intake over the first 70 days of gestation (dGA). Fetuses from control (C) and nutrient-restricted (R) ewes were chronically catheterised and response profiles for ACTH and cortisol were determined at 113-116 and 125-127 dGA after administration of corticotrophin releasing hormone (CRH) and arginine vasopressin (AVP). At 126-128 dGA cortisol profiles were also determined following ACTH administration. Basal ACTH and cortisol concentrations were not different between C and R fetuses. In R fetuses, ACTH response to CRH+AVP was significantly smaller at 113-116 dGA (P<0.01), and cortisol responses were smaller at both 113-116 dGA (P<0.01) and 125-127 dGA (P<0.0001). Cortisol response to ACTH was also smaller in R fetuses (P<0.001). We conclude that, in late gestation fetal sheep, pituitary and adrenal responsiveness is reduced following modest maternal nutrient restriction in early gestation.     

Impact of maternal undernutrition on the hypothalamic-pituitary-adrenal axis responsiveness in sheep at different ages postnatal

Epidemiological and experimental data support the hypothesis of 'fetal programming', which proposes that alterations in fetal nutrition and endocrine status lead to permanent adaptations in fetal homeostatic mechanisms, producing long-term changes in physiology and determine susceptibility to later disease. Altered hypothalamic-pituitary-adrenal (HPA) axis function has been proposed to play an important role in programming of disease risk. The aim of the present study was to examine the effects of maternal nutrient restriction imposed during different periods of gestation on the HPA axis function in sheep, at different ages postnatal. Pregnant ewes were fed a 50% nutrient-restricted diet from days 0-30 (group R1, n = 7), or from days 31-100 of gestation (group R2, n = 7) or a control 100% diet throughout pregnancy, (Control, n = 8). Blood samples were collected at 10-day intervals from day 40 of gestation to term. Lambs were born naturally and fed to appetite throughout the study period. At 2, 5.5, and 10 months of age lambs were given an i.v. injection of corticotrophin-releasing hormone (CRH) and blood samples were collected at -15, 0, 15, 30, 60, 120, and 180 min postinjection. Maternal cortisol levels were significantly higher (P < 0.05) in group R1 compared with the other two groups, whereas maternal insulin levels were lower (P < 0.05) in group R2 compared with control. Birth weight of lambs was not affected by the maternal nutritional manipulation. The area under the curve for ACTH and cortisol response to CRH challenge was greater (P < 0.05) in lambs of group R1 at two months of age, whereas no difference was detected at the ages of 5.5 and 10 months. However, significantly higher (P < 0.01) basal cortisol levels were observed in lambs of R1 group at 5.5 months of age. There was no interaction between treatment and sex for both pituitary and adrenal responses to the challenge. A significant sex effect was evident with females responding with higher ACTH and cortisol levels at the age of 5.5 months (P < 0.01, P < 0.001 respectively) and with higher cortisol levels (P < 0.01) at 10 months of age than males. It is concluded that the HPA axis is programmable by altered nutrition in utero. The sensitivity of the axis to exogenous stimulation is enhanced during early postnatal life and attenuated with age, suggesting a role for the postnatal influences in resetting of the HPA axis and emphasizing the importance of identifying the impact of maternal undernutrition at several time points after birth.     

Evidence that the central noradrenergic and adrenergic pathways activate the hypothalamic-pituitary-adrenal axis in the sheep.

These studies were undertaken to test the hypothesis that stimulation of the central noradrenergic and adrenergic pathways activates the hypothalamic-pituitary-adrenal axis in vivo in the conscious sheep. Blood samples were taken at 10-min intervals over 4 h to establish the baseline state, and then each animal received an intracerebroventricular (icv) injection of NaCl (control animals) or catecholamine [norepinephrine (NE) or epinephrine (EPI)]. A more frequent rate of venous sampling was used for the 30-min period after the icv injection, after which time the 10-min rate of blood sampling was continued for another 3.5 h. NaCl (n = 4) caused no change in pituitary-adrenal secretion. In contrast, 10 micrograms NE (n = 4) caused acute 1.9- and 3.2-fold increases in mean plasma ACTH and cortisol levels over the 1 h period post injection, and 1.6- and 2.3-fold increments in their concentrations over the 4 h postinjection period. Although 10 micrograms EPI (n = 4) did not elevate mean plasma ACTH, it produced significant 1.7- and 1.5-fold increases in plasma cortisol during the 1- and 4-h periods post injection. However, when 100 micrograms EPI was injected (n = 4), acute 9.5- and 5.5-fold increases in plasma ACTH and cortisol were seen over the 1 h period post injection, and 6.1- and 4.2-fold increments in their plasma concentration were noted during the entire post-injection period. To determine the predominant site of action of the catecholamines, we also examined the ability of NE and EPI to release ACTH from cultured ovine anterior pituitary cells. NE and EPI (10(-9)-10(-6) M) stimulated the release of ACTH in a dose-dependent manner, but with maximal increments only 1.5-fold greater than the basal secretion. NE and EPI also increased the maximal ACTH response to CRF, but did not alter the maximal ACTH release induced by arginine vasopressin.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of periconceptional undernutrition and gender on hypothalamic-pituitary-adrenal axis function in young adult sheep

Glucocorticoids are proposed to act as intermediary factors that transcribe the developmental programming sequelae of maternal nutrient restriction (NR). Periconceptional under-nutrition of sheep markedly activates fetal hypothalamic-pituitary-adrenal (HPA) axis activity leading to preterm birth, while transient undernutrition during late gestation in sheep programs adult HPA axis function. To date, no study has examined resting or stimulated HPA axis function in young adult offspring following a periconceptional nutritional challenge. In the present study, 20 ewes were either periconceptionally undernourished (50% metabolisable energy requirements from days 1 to 30 gestation; NR, n = 8) or fed to control levels (100% requirement; controls, n = 12) to term (147 days gestation). Ewes were blood sampled remotely at 2 and 30 days using automated blood sampling equipment. Thereafter, offspring (controls, n = 6/6 males/females; NR, n = 4/4 males/females) were reared to 1 year of age and on separate days received either an i.v. corticotrophin-releasing hormone (CRH; 0.5 microg/kg) and vasopressin (AVP; 0.1 microg/kg) challenge or a synthetic ACTH i.v. bolus (Synacthen; 1.25 microg/kg), and blood samples were taken (manually and remotely) at appropriate intervals for measurement of plasma ACTH and cortisol accordingly. Resting plasma cortisol, assessed remotely, was similar in ewes during undernutrition (control 18.3 +/- 1.4 vs NR 23.4 +/- 1.9 nmol/l) and in offspring at 4 months of age (control male 17.6 +/- 2.9; control female 17.2 +/- 0.4, NR male 16.5 +/- 3.1, NR female 21.7 +/- 4.0 nmol/l). At 12 months of age, however, resting plasma cortisol was significantly increased in NR females (control male 28.0 +/- 1.5, control female 32.9 +/- 9, NR male 32 +/- 7, NR female 53 +/- 10 nmol/l, F 5.7, P = 0.02) despite no difference in plasma ACTH concentration. There was an interaction between nutritional group and gender for both the pituitary and adrenal responses to CRH and AVP, i.e. for controls, females exhibited increased plasma ACTH or cortisol relative to males but for NR this trend was either not present or reversed. The adrenocortical response to synthetic ACTH was gender-dependent only, being greater in female offspring. Combined CRH and AVP provoked a transient hypertension and marked bradycardia in all animals, irrespective of dietary group or gender and could be effectively reproduced by an AVP bolus alone. In conclusion, the present study has shown that periconceptional undernutrition of sheep has only a minor influence on HPA axis function in their young adult offspring when considered alongside the effect of gender per se.     

Studies of the regulation of the hypothalamic-pituitary-adrenal axis in sheep with hypothalamic-pituitary disconnection. I. Effect of an audiovisual stimulus and insulin-induced hypoglycemia

These studies were undertaken to characterize the secretion of adrenocorticotropin (ACTH), immunoreactive (ir) beta-endorphin (ir-beta-EP) and ir alpha-melanocyte-stimulating hormone (ir-alpha-MSH) from the surgically isolated ovine pituitary in response to an audiovisual stress (barking dog, 3 min) and insulin hypoglycemia. The studies were performed in 4 ovariectomized, hypothalamo-pituitary-disconnected (HPD) and 4 sham-HPD ewes bearing indwelling jugular venous catheters. Basal concentrations of the three pro-opiomelanocortin (POMC) peptides and plasma cortisol were significantly increased in the HPD animals. When the control ewes were exposed to the audiovisual stimulus, plasma ACTH, ir-beta-EP and ir-alpha-MSH levels were increased 2.5-, 10-, and 5-fold 1 min after the stress; plasma cortisol attained maximal values at 5 min. In contrast, plasma levels of the three POMC peptides were not significantly increased in the HPD animals, although a rise in plasma cortisol occurred. The administration of regular insulin (5 units/kg i.v.) to control ewes caused plasma ACTH, ir-beta-EP, and ir-alpha-MSH levels to increase 17-, 22-, and 67-fold at 50 min; plasma cortisol values were maximal at 60 min. In contrast, the elevated basal levels of POMC peptides in the HPD animals were not significantly increased by the hypoglycemia, but a significant elevation of plasma cortisol was seen. We conclude that: (1) the increase in ACTH in intact animals after an audiovisual emotional stress and hypoglycemia, and the abolition of this increase by HPD, indicates that both stimuli, each acting through distinct neuroanatomical pathways, increase the net corticotropin-releasing activity of the hypothalamus; (2) the rise in plasma cortisol in HPD animals after stress suggests that peripheral humoral factors may release additional small amounts of ACTH from the anterior pituitary, and (3) the finding of increased basal ACTH levels after HPD suggests that POMC peptide synthesis and secretion by the anterior pituitary is tonically regulated by an inhibitory factor of hypothalamic origin.     

Acute-stress-induced facilitation of the hypothalamic-pituitary-adrenal axis

It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis responds to a stressor by secreting facilitatory and inhibitory factors. During a stressor, the relative magnitude of secretion of these factors determines the responsiveness of the HPA axis to a subsequent stressor. Previous studies have suggested that corticosterone (B) secreted during the first stressor is an inhibitory factor. We hypothesized that the transient removal of the inhibitory factor, B, during the first stressor would result in the secretion of only facilitatory factors. This would cause the HPA axis to exist in a state of hyperresponsiveness, and to hypersecrete corticotropin (ACTH) and B in response to a second stressor. Therefore, our primary objective was to demonstrate stress-induced facilitation of the HPA axis response to a subsequent stressor. Male Sprague-Dawley rats were subjected to a 1-hour physical immobilization stressor (IMM) or administered a single dose of ACTH on day 1. B response during these treatments was markedly but transiently attenuated with an 100 mg/kg i.p. dose of aminoglutethimide (AG). Twenty-four hours later, rats were subjected to an intraperitoneal saline injection stressor. B and ACTH levels were measured 15 min after the injection stressor. Rats treated with AG plus IMM on day 1 hypersecreted B and ACTH after the injection stressor on day 2. These results suggest that immobilization stress induces facilitation of both pituitary and adrenal responses. Exogenous administration of ACTH- to AG-pretreated rats on day 1, in lieu of immobilization stress, did not affect the responsiveness of the HPA axis on day 2. This suggests that ACTH secreted during the first stressor does not play an important role in acute-stress-induced facilitation.     

Normal opioid tone and hypothalamic-pituitary-adrenal axis function in chronic fatigue syndrome despite marked functional impairment

OBJECTIVE: To determine whether the functional impairment seen in chronic fatigue syndrome (CFS) is associated with reduced levels of central opioids and/or deficiency of the hypothalamic-pituitary-adrenal (HPA) axis. DESIGN: Single-blinded case-control study measuring functional and psychological status, basal hormonal parameters and ACTH/cortisol response to naloxone and ovine corticotrophin-releasing hormone (oCRH) vs. placebo in people with CFS and healthy controls. PATIENTS: Twelve people with CFS and 11 age-matched controls. MEASUREMENTS: Hormonal parameters: basal levels of 09:00 h plasma cortisol, dehydroepiandrosterone sulfate (DHEAS) and IGF-1. 24-h urinary free cortisol. Plasma ACTH and cortisol response to naloxone 125 microg/kg, oCRH 1 microg/kg and placebo (normal saline). Psychological parameters: SF-36, Hamilton Depression Score, Hospital Anxiety and Depression Scale and Fatigue Scale. RESULTS: There were highly significant differences between the CFS subjects and the controls with respect to the measures of fatigue and physical functioning. However, there were no differences in basal levels of 09:00 h cortisol (367 +/- 37 vs. 331 +/- 39 nmol/l, P = 0.51), DHEAS (4.2 +/- 0.6 vs. 4.0 +/- 0.5 micromol/l, P = 0.81), 24-h urinary free cortisol (182 +/- 27 vs. 178 +/- 21 nmol/24 h, P = 0.91) or IGF-1 (145 +/- 19 vs. 130 +/- 11 microg/l, P = 0.52) between the CFS group and controls, respectively. There was also no difference between the groups with respect to the ACTH and cortisol response to either oCRH or naloxone. CONCLUSIONS: Our data do not support an aetiological role for deficiency in central opioids or the HPA axis in the symptoms of CFS.     

Role of the hypothalamic-pituitary-adrenal axis in rheumatoid arthritis

ObjectiveA subnormal response of the hypothalamic-pituitary-adrenal (HPA) axis to inflammatory stimuli was found to be associated with the occurrence of chronic arthritis in Lewis rats. This study was carried out to determine the role of the HPA axis in patients with rheumatoid arthritis (RA).MethodsThirty patients with RA of less than 2 years duration were studied. Laboratory tests including ESR, RF and X-ray hands were performed in all patients. All patients were subjected to the standard insulin-induced hypoglycemia test to determine the integrity of the HPA axis. Serum cortisol was estimated at 11 PM on the day prior to the test in eight of these patients.ResultsTwelve out of 30 patients had subnormal cortisol response to insulin-induced hypoglycemia. (normal: cortisol >20 μg/dl and 7 μg > basal cortisol). Two patients had a maximal cortisol response 7 μg > basal but less than 20 μg/dl, i.e. a partial response. Seven patients had a supranormal basal cortisol with no further stimulation with hypoglycemia. Nine patients had an adequate response.Conclusion21/30 (70%) of patients showed some abnormality of HPA axis response. We propose that a primary abnormality of the HPA axis may play a significant role in the pathogenesis of RA.     

Differential menstrual cycle regulation of hypothalamic-pituitary-adrenal axis in women with premenstrual syndrome and controls

Previous studies in animals indicate that reproductive steroids are potent modulators of the hypothalamic-pituitary-adrenal (HPA) axis, a physiologic system that is typically dysregulated in affective disorders, such as major depression. Determination of the role of reproductive steroids in HPA axis regulation in humans is of importance when attempting to understand the pathophysiology of premenstrual syndrome (PMS), a disorder characterized by affective symptoms during the luteal phase of the menstrual cycle. We performed two studies using treadmill exercise stress testing to determine the effect of menstrual cycle phase and diagnosis on the HPA axis in women with PMS and controls and the role of gonadal steroids in HPA axis modulation in control women. The results of these studies indicate that women with PMS fail to show the normal increased HPA axis response to exercise during the luteal phase and that progesterone, not estradiol, produces increased HPA axis response to treadmill stress testing in control women. These data demonstrate that women with PMS, when symptomatic, appear to have an abnormal response to progesterone and, furthermore, do not display the HPA axis abnormalities characteristic of major depression.     

Dehydroepiandrosterone sulfate in the assessment of the hypothalamic-pituitary-adrenal axis

CONTEXT: The role of dehydroepiandrosterone-sulfate (DHEA-S) in assessing the integrity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with suspected insufficiency is uncertain. OBJECTIVE: The objective of the study was to prospectively evaluate the diagnostic value of DHEA-S on HPA function in consecutive patients with suspected HPA insufficiency with and without pituitary lesions at a tertiary referral center. DESIGN AND PATIENTS: In 70 consecutive patients, insulin tolerance test was accompanied by measurement of basal DHEA-S. Assessment of HPA axis was based on peak cortisol response in insulin tolerance test (normal > or = 550 nmol/liter). To account for the age and gender dependency of DHEA-S, a z-score was calculated using age- and gender-specific reference values of the assay. RESULTS: Individuals with HPA insufficiency had significantly lower z-scores than those with normal HPA function (-1.66 vs. -0.62, P < 0.0001). In individuals up to 30 yr of age, a z-score of -2.0 had 100% sensitivity and specificity regarding HPA function [area under receiver operating characteristics (ROC) curve 1.00], whereas z-scores proved less useful in older individuals. In individuals with pituitary macroadenoma, a z-score below -2.0 had 100% specificity to predict HPA insufficiency (area under ROC curve 0.82). In the absence of a pituitary adenoma, the diagnostic value of the z-score was reduced (area under ROC curve 0.71). CONCLUSIONS: Individuals with HPA insufficiency have lower z-scores for DHEA-S than those with normal HPA function. There is evidence that a z-score could be of diagnostic value in assessing HPA integrity, especially in younger patients and patients with pituitary macroadenoma, but further studies are needed to consolidate these findings.