Ildiko Halasz

Fast Glucocorticoid Feedback Inhibition of ACTH Secretion in the Ovariectomized Rat: Effect of Chronic Estrogen and Progesterone

The purpose of this study was to determine whether estrogen and progesterone influence fast glucocorticoid negative feedback regulation of the ACTH and corticosterone (CORT) responses to stress. Mature rats were ovariectomized and 6 weeks later implanted with 17 beta-estradiol (E2, 0.5 mg), E2 and progesterone (P, 100 mg; E2 + P group) or placebo pellets (OVX). Seven days later rats were subjected to a single or repeated intermittent footshock stress (0.2 mA, 15 s duration, 0.5 s on). The repeated stress was of the same intensity and duration, and was applied either during the time domain of the rate-sensitive fast glucocorticoid feedback when plasma CORT levels are rising (5 min after the onset of the first stress), or at the time of peak CORT response (15 min) to the initial stress. Plasma ACTH and CORT were measured from serial samples. Estrogen replacement alone or in combination with progesterone lowered the immediate (t = 5) ACTH and CORT response to a single stress in ovariectomized animals. The second stress applied 5 min after the initial stress produced net ACTH responses similar to those obtained after a single stress in the OVX and E2 + P-replaced hormone groups, while total ACTH responses were lower in the E2-treated group. In ovariectomized animals, a facilitation of ACTH response by a prior stress is apparent in response to a footshock 15 min later, when the integrated ACTH secretion is significantly greater than the response measured after a single shock, or after a repeated shock 5 min apart. Anterior pituitary proopiomelanocortin (POMC) mRNA levels were lower in groups with E2 or E2 + P replacement compared to OVX animals. In contrast, hypothalamic corticotropin-releasing factor (CRF) mRNA levels did not increase significantly. However, hypothalamic glucocorticoid receptor (GR) mRNA levels increased after 17 beta-estradiol treatment, and this increase was reversed by progesterone. These results suggest that prior stress leads to both a fast-feedback inhibition and a facilitation of the subsequent stress response. In the absence of gonadal hormones this facilitation is balanced by fast-feedback inhibition during the glucocorticoid fast-feedback time domain, and is unmasked outside of this time domain. Estrogen suppresses POMC mRNA synthesis leading to a decrease in the availability of releasable ACTH, thereby reducing the facilitation. Progesterone may counter this effect of estrogen by decreasing the efficacy of the fast rate-sensitive glucocorticoid negative feedback.

Sexually dimorphic effects of alcohol exposure in utero on neuroendocrine and immune functions in chronic alcohol-exposed adult rats.

Maternal ethanol consumption has deleterious effects on the offsprings neuroendocrine and T-cell-dependent functions. Chronic alcohol consumption in adulthood has also been associated with activated hypothalamic-pituitary-adrenal (HPA) function and immunosuppression which is demonstrable at the T-cell level. Our aim was to establish whether prenatal alcohol exposure alters the neuroendocrine and immune responses to chronic alcohol challenge in adult male and female offspring. Adult male rats placed on a liquid alcohol diet for 5 weeks had significantly decreased thymus weight, hypertrophied adrenals, and elevated plasma ACTH and corticosterone levels. Splenic lymphocyte Concanavalin A (Con A)-stimulated proliferation in the ethanol-treated rats was decreased compared to that in pair-fed controls. Thus, prolonged alcohol exposure activated the HPA axis and suppressed T-cell function. The effects of prenatal alcohol exposure, as a predispositional factor, on the HPA axis and on the T-cell functions of adult chronic alcohol-exposed rats were examined in the offspring of dams fed ethanol (FAE) or an isocaloric liquid (PF) diet during the last 2 weeks of gestation. The adult offspring of both sexes and prenatal treatment groups were then placed on an alcohol-containing liquid diet for 5 weeks. Fetal alcohol exposure decreased anterior pituitary proopiomelanocortin mRNA levels and increased glucocorticoid receptor (GR) mRNA levels in males and decreased GR mRNA levels in females. There were no differences in hypothalamic CRF mRNA and GR mRNA levels between the prenatal treatment groups. There was no significant difference in Con A-stimulated lymphocyte proliferation between FAE and PF males. However, FAE females showed Con A-stimulated lymphocyte proliferation significantly higher than those of all other groups, including pair-fed females. Prostaglandin E(2) (PGE(2)) suppressed lymphocyte proliferation to a lesser degree in FAE males than in any other group. Furthermore, T-cell response to Con A was enhanced by indomethacin, a prostaglandin biosynthesis inhibitor, in FAE males suggesting that increased prostaglandin synthesis may occur in FAE males after chronic alcohol exposure. Increased levels of endogenous PGE(2) could also be inferred from the enhanced levels of interleukin-2 receptor alpha (IL-2Ralpha) mRNA in activated lymphocytes of male but not of female FAE offspring compared to PF. In summary, the results of this study demonstrate that prenatal alcohol exposure leads to a specific HPA-related vulnerability in males to the deleterious effects of ethanol in adulthood. Although prenatal alcohol did not further aggravate the effects of chronic alcohol exposure on lymphocyte proliferation response to Con A in adult male offspring, altered T-cell responses could be unmasked.

Bioimpedance analysis of body composition in an international twin cohort.

OBJECTIVE Multiple twin studies have demonstrated the heritability of anthropometric and metabolic traits. However, assessment of body composition parameters by bioimpedance analysis (BIA) has not been routinely performed in this setting. DESIGN A cross-sectional study. SETTING Study subjects were recruited and assessed at twin festivals or at major university hospitals in Italy, Hungary, and the United States to estimate the influence of genetic and environmental components on body composition parameters in a large, wide age range, international twin cohort by using bioelectrical impedance analysis. SUBJECTS 380 adult twin pairs (230 monozygotic and 150 dizygotic pairs; male:female ratio, 68:32; age years 49.1 ± 15.4; mean ± standard deviation; age range 18-82) were included in the analysis. RESULTS Heritability was calculated for weight (82%; 95% confidence interval [CI]: 78-85), waist and hip circumferences (74%; 95%CI: 68-79), body fat percentage (74%; 95%CI: 69-79), fat-free mass (74%; 95%CI: 69-79) and body mass index (79%; 95%CI: 74-83). The completely environmental model showed no impact of shared environmental effects on the variance, while unshared environmental effects were estimated as between 18% and 26%. CONCLUSIONS BIA findings provide additional evidence to the heritability of anthropometric attributes related to obesity and indicate the practical value of this simple method in supporting efforts to prevent obesity-related adverse health events.

Corticotropin-releasing hormone and proopiomelanocortin gene expression is altered selectively in the male rat fetal thymus by maternal alcohol consumption

The present study was carried out to investigate how hormonal changes caused by chronic alcohol exposure of rats during the late period of gestation are coordinated with neuroendocrine functions of the fetal thymus, namely thymic expression of CRH and POMC genes. Alcohol consumption by pregnant dams led to a 5-fold elevation of plasma corticosterone (CORT) levels and significantly decreased fetal CORT levels. This generally inverse correlation between maternal and fetal CORT was absent in alcohol-consuming dams and their male fetuses on day 19 of gestation. These day 19 fetuses also had an attenuated plasma testosterone surge that occurred in the male control (pair-fed) fetus on day 19 of embryonic life. Furthermore, fetal alcohol exposure (FAE) resulted in a significant increase in thymic CRH and a decrease in thymic POMC expression in the male fetuses only, specifically on embryonic day 19. Thus, the strong positive correlation between CRH and POMC gene expression in the thymus of pair-fed male and female FAE fetuses was abolished in the FAE males. However, regardless of embryonic age or treatment, a strong positive correlation between thymic POMC gene expression and plasma testosterone levels in the male fetuses was detected. These data suggest that the sexually dimorphic effect of FAE on the fetal thymic POMC and CRH expression in males is driven by testosterone and may be related, therefore, to the presence of alcohol at the time of the prenatal testosterone surge in the male fetuses.

Alcohol Consumption and Risk of Coronary Artery Disease (from the Million Veteran Program)

Moderate alcohol consumption has been associated with a lower risk of coronary artery disease (CAD) in the general population but has not been well studied in US veterans. We obtained self-reported alcohol consumption from Million Veteran Program participants. Using electronic health records, CAD events were defined as 1 inpatient or 2 outpatient diagnosis codes for CAD, or 1 code for a coronary procedure. We excluded participants with prevalent CAD (n = 69,995) or incomplete alcohol information (n = 8,449). We used a Cox proportional hazards model to estimate hazard ratios and 95% confidence intervals for CAD, adjusting for age, gender, body mass index, race, smoking, education, and exercise. Among 156,728 participants, the mean age was 65.3 years (standard deviation = 12.1) and 91% were men. There were 6,153 CAD events during a mean follow-up of 2.9 years. Adjusted hazard ratios (95% confidence intervals) for CAD were 1.00 (reference), 1.02 (0.92 to 1.13), 0.83 (0.74 to 0.93), 0.77 (0.67 to 0.87), 0.71 (0.62 to 0.81), 0.62 (0.51 to 0.76), 0.58 (0.46 to 0.74), and 0.95 (0.85 to 1.06) for categories of never drinker; former drinker; current drinkers of ≤0.5 drink/day, >0.5 to 1 drink/day, >1 to 2 drinks/day, >2 to 3 drinks/day, and >3 to 4 drinks/day; and heavy drinkers (>4 drinks/day) or alcohol use disorder, respectively. For a fixed amount of ethanol, intake at ≥3 days/week was associated with lower CAD risk compared with ≤1 day/week. Beverage preference (beer, wine, or liquor) did not influence the alcohol-CAD relation. Our data show a lower risk of CAD with light-to-moderate alcohol consumption among US veterans, and drinking frequency may provide a further reduction in risk.