The Experts below are selected from a list of 2184 Experts worldwide ranked by ideXlab platform
James L Abelson - One of the best experts on this subject based on the ideXlab platform.
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effect of repeat exposure on neuroendocrine and symptom responses to pentagastrin
Psychiatry Research-neuroimaging, 2004Co-Authors: Samir Khan, Israel Liberzon, James L AbelsonAbstract:The cholecystokinin (CCK-B) agonist pentagastrin stimulates dose-dependent release of Adrenocorticotropin (ACTH) and cortisol in humans, likely via direct pharmacological action at pituitary CCK-B receptors. Pentagastrin also produces side effects, however, which may be experienced as novel or anxiety arousing and could contribute to ACTH release. Available data suggest that pentagastrin's activation of the hypothalamic-pituitary-adrenal (HPA) axis is unrelated to anxiety symptoms themselves, but novelty effects have not been examined in this model and do strongly activate this system in animals. To further explore the impact of novelty and anxiety symptoms on HPA responses, pentagastrin was administered twice to 12 subjects (six male, six female) under single-blind conditions. Repeat pentagastrin injection was associated with a slight habituation in the magnitude of symptom and HPA axis responses, but robust HPA and symptom responses were seen following both injections. No relationships were found between anxiety symptoms and HPA activity and the modest symptomatic and neuroendocrine habituation appeared to occur independently. Pentagastrin may release ACTH and cortisol through direct pharmacological action, perhaps enhanced on first exposure by psychologically mediated novelty effects. Novelty, per se, is not likely the primary mediator of the HPA response. This model may be useful for further study of cognitive-emotional modulators of HPA axis activity.
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hypothalamic pituitary adrenal response to cholecystokinin b receptor agonism is resistant to cortisol feedback inhibition
Psychoneuroendocrinology, 2003Co-Authors: James L Abelson, Elizabeth A. YoungAbstract:Intravenous injection of the cholecystokinin (CCK)-B receptor agonist, pentagastrin, produces robust, dose-dependent release of Adrenocorticotropin (ACTH) and cortisol, supporting the hypothesis that CCK-B agonists pharmacologically activate the hypothalamic-pituitary-adrenal (HPA) axis. The mechanism of activation and its physiological relevance remain uncertain. Preliminary data suggest that the ACTH response to pentagastrin may be differentiated from the response to exogenous corticotropin releasing hormone (CRH) by its relative resistance to cortisol feedback inhibition. To more directly test the relationship between cortisol levels and ACTH response to pentagastrin, this study examined responses to pentagastrin (a) during a peak (8 a.m.) and a nadir (4 p.m.) period of endogenous cortisol secretion and (b) when cortisol levels were artificially reduced to low levels by administration of metyrapone. ACTH responses to pentagastrin were identical in the morning and afternoon, despite substantial differences in basal cortisol levels. Suppression of cortisol with metyrapone had little impact on ACTH response to pentagastrin. These data support the hypothesis that CCK-B receptor mediated activation of the HPA axis is relatively resistant to cortisol feedback inhibition. This differentiates it from CRH-mediated activation and raises the possibility that CCK could contribute to acute activation of the HPA axis even in the face of elevated basal cortisol levels, such as those seen in chronic stress or some psychiatric disorders.
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hypothalamic pituitary adrenal axis activity in panic disorder effects of alprazolam on 24 h secretion of Adrenocorticotropin and cortisol
Journal of Psychiatric Research, 1996Co-Authors: James L Abelson, George C Curtis, Oliver G CameronAbstract:Pre-clinical and some clinical evidence suggests that central overdrive within the hypothalamic-pituitary-adrenal (HPA) axis may play a role in panic disorder, and that the anti-panic efficacy of alprazolam may involve its ability to inhibit this drive. Detailed examination of 24 h secretion of Adrenocorticotropin (ACTH) and cortisol in 20 panic patients had revealed subtle HPA axis abnormalities prior to treatment. In order to determine whether these abnormalities resolve with alprazolam therapy, these patients were re-studied over a full circadian cycle after 12 weeks on alprazolam. Alprazolam produced substantial improvement in clinical status which was accompanied by nearly full resolution of pre-treatment hypercortisolemia. The impact of treatment on ACTH was more complex and influenced by symptom severity. The results are consistent with the hypotheses that HPA axis regulation is subtly disturbed in panic disorder and that impact on the HPA axis may play a role in alprazolam's mechanism of efficacy.
Christoph Ozdoba - One of the best experts on this subject based on the ideXlab platform.
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selective inferior petrosal sinus sampling without venous outflow diversion in the detection of a pituitary adenoma in cushing s syndrome
Neuroradiology, 2012Co-Authors: Lukas Andereggen, Gerhard Schroth, Jan Gralla, Rolf W. Seiler, Luigi Mariani, Jürgen Beck, H.r. Widmer, Robert H. Andres, Emanuel Christ, Christoph OzdobaAbstract:Introduction Conventional MRI may still be an inaccurate method for the non-invasive detection of a microadenoma in Adrenocorticotropin (ACTH)-dependent Cushing’s syndrome (CS). Bilateral inferior petrosal sinus sampling (BIPSS) with ovine corticotropin-releasing hormone (oCRH) stimulation is an invasive, but accurate, intervention in the diagnostic armamentarium surrounding CS. Until now, there is a continuous controversial debate regarding lateralization data in detecting a microadenoma. Using BIPSS, we evaluated whether a highly selective placement of microcatheters without diversion of venous outflow might improve detection of pituitary microadenoma.
William E Rainey - One of the best experts on this subject based on the ideXlab platform.
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acute and chronic regulation of aldosterone production
Molecular and Cellular Endocrinology, 2012Co-Authors: Namita G Hattangady, Lawrence O Olala, Wendy B Bollag, William E RaineyAbstract:Aldosterone is the major mineralocorticoid synthesized by the adrenal and plays an important role in the regulation of systemic blood pressure through the absorption of sodium and water. Aldosterone production is regulated tightly by selective expression of aldosterone synthase (CYP11B2) in the adrenal outermost zone, the zona glomerulosa. Angiotensin II (Ang II), potassium (K(+)) and Adrenocorticotropin (ACTH) are the main physiological agonists which regulate aldosterone secretion. Aldosterone production is regulated within minutes of stimulation (acutely) through increased expression and phosphorylation of the steroidogenic acute regulatory (StAR) protein and over hours to days (chronically) by increased expression of the enzymes involved in the synthesis of aldosterone, particularly CYP11B2. Imbalance in any of these processes may lead to several disorders of aldosterone excess. In this review we attempt to summarize the key molecular events involved in the acute and chronic phases of aldosterone secretion.
Wendy B Bollag - One of the best experts on this subject based on the ideXlab platform.
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acute and chronic regulation of aldosterone production
Molecular and Cellular Endocrinology, 2012Co-Authors: Namita G Hattangady, Lawrence O Olala, Wendy B Bollag, William E RaineyAbstract:Aldosterone is the major mineralocorticoid synthesized by the adrenal and plays an important role in the regulation of systemic blood pressure through the absorption of sodium and water. Aldosterone production is regulated tightly by selective expression of aldosterone synthase (CYP11B2) in the adrenal outermost zone, the zona glomerulosa. Angiotensin II (Ang II), potassium (K(+)) and Adrenocorticotropin (ACTH) are the main physiological agonists which regulate aldosterone secretion. Aldosterone production is regulated within minutes of stimulation (acutely) through increased expression and phosphorylation of the steroidogenic acute regulatory (StAR) protein and over hours to days (chronically) by increased expression of the enzymes involved in the synthesis of aldosterone, particularly CYP11B2. Imbalance in any of these processes may lead to several disorders of aldosterone excess. In this review we attempt to summarize the key molecular events involved in the acute and chronic phases of aldosterone secretion.
Adrian J L Clark - One of the best experts on this subject based on the ideXlab platform.
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Bioluminescence resonance energy transfer reveals the Adrenocorticotropin (ACTH)-induced conformational change of the activated ACTH receptor complex in living cells.
Endocrinology, 2010Co-Authors: Sadani N Cooray, Tengteng Chung, Khansa Mazhar, László Szidonya, Adrian J L ClarkAbstract:Bioluminescence resonance energy transfer analysis is used to study the interaction between melanocortin 2 receptor (MC2R) accessory protein and the MC2R and provides evidence for protein kinase A-dependent conformational changes in the receptor complex following receptor activation.
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interaction of the melanocortin 2 receptor with nucleoporin 50 evidence for a novel pathway between a g protein coupled receptor and the nucleus
The FASEB Journal, 2007Co-Authors: Marina Doufexis, Helen L Storr, Peter J King, Adrian J L ClarkAbstract:The Adrenocorticotropin (ACTH) receptor (melanocortin 2 receptor, or MC2R) is the smallest G-protein-coupled receptor that, when activated by the peptide hormone ACTH, stimulates cAMP production an...