Glucocorticoid Negative Feedback (glucocorticoid + negative_feedback)

Distribution by Scientific Domains


Selected Abstracts


CLINICAL AND IMAGING STUDY: Glucocorticoid negative feedback in methadone-maintained former heroin addicts with ongoing cocaine dependence: dose,response to dexamethasone suppression

ADDICTION BIOLOGY, Issue 1 2006
Bruno Aouizerate
ABSTRACT Combined cocaine and illicit opiate use is common. This study aimed to test the hypothesis that cocaine dependence in former heroin-addicted patients maintained on methadone treatment is associated with enhanced glucocorticoid negative feedback. Multiple dose dexamethasone suppression tests, using a conventional 2.0 mg dose, and two lower doses, 0.5 mg and 0.125 mg, were performed in 10 methadone-maintained former heroin addicts with ongoing cocaine dependence (C-MM), 10 stabilized methadone-maintained former heroin addicts with no ongoing drug or alcohol use (MM), and 22 normal volunteers (NV). At 9 hours, there was no difference in plasma adrenocorticotropin hormone (ACTH) and/or cortisol levels among groups on the baseline day, as well as after the two lower doses of dexamethasone. At 17 hours, C-MM and MM had significantly lower plasma ACTH and/or cortisol levels than NV. However, C-MM did not significantly differ from MM in their hormonal levels. When the hormonal responses to dexamethasone are expressed as magnitude of lowering from baseline, there was no significant difference at any dose among groups. Therefore, C-MM exhibited a normal glucocorticoid negative feedback in the morning. Using the standard interpretation of dexamethasone suppression testing based on the examination of the actual hormonal levels rather than the difference from baseline condition, C-MM appear to have glucocorticoid effects similar to MM, yet were both greater than NV in the late afternoon. Thus, further studies are needed to know whether altered glucocorticoid negative feedback is related to chronic cocaine exposure, or is the result of former heroin addiction and/or its long-term treatment with methadone. [source]


Hypothalamic-Pituitary-Adrenal Axis Abnormalities in Response to Deletion of 11,-HSD1 is Strain-Dependent

JOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2009
R. N. Carter
Inter-individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity underlie differential vulnerability to neuropsychiatric and metabolic disorders, although the basis of this variation is poorly understood. 11,-Hydroxysteroid dehydrogenase type 1 (11,-HSD1) has previously been shown to influence HPA axis activity. 129/MF1 mice null for 11,-HSD1 (129/MF1 HSD1,/,) have greatly increased adrenal gland size and altered HPA activity, consistent with reduced glucocorticoid negative feedback. On this background, concentrations of plasma corticosterone and adrenocorticotrophic hormone (ACTH) were elevated in unstressed mice, and showed a delayed return to baseline after stress in HSD1-null mice with reduced sensitivity to exogenous glucocorticoid feedback compared to same-background genetic controls. In the present study, we report that the genetic background can dramatically alter this pattern. By contrast to HSD1,/, mice on a 129/MF1 background, HSD1,/, mice congenic on a C57Bl/6J background have normal basal plasma corticosterone and ACTH concentrations and exhibit normal return to baseline of plasma corticosterone and ACTH concentrations after stress. Furthermore, in contrast to 129/MF1 HSD1,/, mice, C57Bl/6J HSD1,/, mice have increased glucocorticoid receptor expression in areas of the brain involved in glucocorticoid negative feedback (hippocampus and paraventricular nucleus), suggesting this may be a compensatory response to normalise feedback control of the HPA axis. In support of this hypothesis, C57Bl/6J HSD1,/, mice show increased sensitivity to dexamethasone-mediated suppression of peak corticosterone. Thus, although 11,-HSD1 appears to contribute to regulation of the HPA axis, the genetic background is crucial in governing the response to (and hence the consequences of) its loss. Similar variations in plasticity may underpin inter-individual differences in vulnerability to disorders associated with HPA axis dysregulation. They also indicate that 11,-HSD1 inhibition does not inevitably activate the HPA axis. [source]


Adrenocortical and Pituitary Glucocorticoid Feedback in Abstinent Alcohol-Dependent Women

ALCOHOLISM, Issue 5 2010
Bryon Adinoff
Background:, The long-term ingestion of alcohol diminishes hypothalamic,pituitary,adrenal (HPA) axis reactivity in alcohol-dependent men, potentially altering future relapse risk. Although sex differences in HPA axis functioning are apparent in healthy controls, disruptions in this system have received little attention in alcohol-dependent women. In this study, we assessed the basal secretory profile of adrenocorticotropic hormone (ACTH) and cortisol, adrenocortical sensitivity in both the presence and absence of endogenous corticotropic pituitary activation, and feedback pituitary glucocorticoid sensitivity to dexamethasone. Methods:, Seven women 4- to 8-week abstinent alcohol-only dependent subjects and 10 age-matched female healthy controls were studied. All subjects were between 30 and 50 years old, not taking oral contraceptives, and were studied during the early follicular phase of their menstrual cycle. Circulating concentrations of ACTH and cortisol were measured in blood samples collected at frequent intervals from 2000 to 0800 hour. A submaximal dose of cosyntropin (0.01 ,g/kg), a synthetic ACTH (1,24), was administered at 0800 hour to assess adrenocortical sensitivity. In a separate session, low-dose cosyntropin was also administered following high-dose dexamethasone (8 mg intravenous) to assess adrenocortical sensitivity in the relative absence of endogenous ACTH. In addition, the ACTH response to dexamethasone was measured to determine the pituitary glucocorticoid negative feedback. Sessions were 5 days apart, and blood draws were obtained every 5 to 10 minutes. Results:, Mean concentrations and pulsatile characteristics of ACTH and cortisol over 12 hours were not statistically different between the 2 groups. Healthy controls had a somewhat higher (p < 0.08) net peak, but not net integrated, cortisol response to cosyntropin relative to the alcohol-dependent women. There were no significant group differences in either the ACTH or cortisol response to dexamethasone nor in the net cortisol response to cosyntropin following dexamethasone. Conclusion:, Significant differences in pituitary,adrenal function were not apparent between alcohol-dependent women and matched controls. Despite the small n, it appears that alcohol-dependent women do not show the same disruptions in HPA activity as alcohol-dependent men. These findings may have relevance for gender-specific treatment effectiveness. [source]