The Role of the Pituitary-Adrenal Axis in G-CSF Therapy after Neonatal Hypoxia-Ischemia
type: CreativeWork
description: Several reports indicate that the activity of the hypothalamic-pituitary-adrenal axis (HPA) as measured by the increased level of adrenocorticotropic hormone (ACTH), and corticosterone is increased after a brain insult. These hormones are the effectors secreted respectively by the pituitary and adrenal glands. It has been shown that the down-regulation of corticosterone levels can improve detrimental outcomes associated with ischemic brain injuries. Neonatal hypoxia-ischemia (HI) is a devastating perinatal event with a grim prognosis and limited therapeutic strategies. In recent studies, granulocyte-colony stimulating factor (G-CSF) has shown promise in neonatal HI investigations by improving neuromotor function and reducing apoptosis in the brain. Furthermore, G-CSF is shown in the naïve rat to regulate hormones of the HPA axis. Therefore we hypothesized that G-CSF may in part confer its neuroprotective properties by influencing the pituitary-adrenal response after neonatal HI. To test our hypothesis, metyrapone was administered to inhibit the release of rodent specific glucocorticoid, corticosterone, at the adrenal level. Dexamethasone, a synthetic glucocorticoid, was administered to agonize the effects of corticosterone. Following the Rice-Vannucci model, seven-day old rats (P7) were subjected to unilateral carotid ligation followed by 2.5 hours of hypoxia. Our results show that both G-CSF and metyrapone significantly reduced infarct volume via anti-apoptotic properties but lost its protective effect when combined with dexamethasone. Additionally, G-CSF suppressed the increase of corticosterone in the blood after HI. To investigate the mechanism by which G-CSF modulated corticosterone synthesis, we evaluated its effect in adrenal cortical cells in vitro. Our results indicate that G-CSF activated the JAK/PI3K/Akt/PDE3B pathway, which in turn inhibited corticosterone synthesis. The inhibitors of JAK/PI3K/PDE3B respectively Tyrphostin AG490, LY-294002, and 3-isobuty…
abstract: Several reports indicate that the activity of the hypothalamic-pituitary-adrenal axis (HPA) as measured by the increased level of adrenocorticotropic hormone (ACTH), and corticosterone is increased after a brain insult. These hormones are the effectors secreted respectively by the pituitary and adrenal glands. It has been shown that the down-regulation of corticosterone levels can improve detrimental outcomes associated with ischemic brain injuries. Neonatal hypoxia-ischemia (HI) is a devastating perinatal event with a grim prognosis and limited therapeutic strategies. In recent studies, granulocyte-colony stimulating factor (G-CSF) has shown promise in neonatal HI investigations by improving neuromotor function and reducing apoptosis in the brain. Furthermore, G-CSF is shown in the naïve rat to regulate hormones of the HPA axis. Therefore we hypothesized that G-CSF may in part confer its neuroprotective properties by influencing the pituitary-adrenal response after neonatal HI. To test our hypothesis, metyrapone was administered to inhibit the release of rodent specific glucocorticoid, corticosterone, at the adrenal level. Dexamethasone, a synthetic glucocorticoid, was administered to agonize the effects of corticosterone. Following the Rice-Vannucci model, seven-day old rats (P7) were subjected to unilateral carotid ligation followed by 2.5 hours of hypoxia. Our results show that both G-CSF and metyrapone significantly reduced infarct volume via anti-apoptotic properties but lost its protective effect when combined with dexamethasone. Additionally, G-CSF suppressed the increase of corticosterone in the blood after HI. To investigate the mechanism by which G-CSF modulated corticosterone synthesis, we evaluated its effect in adrenal cortical cells in vitro. Our results indicate that G-CSF activated the JAK/PI3K/Akt/PDE3B pathway, which in turn inhibited corticosterone synthesis. The inhibitors of JAK/PI3K/PDE3B respectively Tyrphostin AG490, LY-294002, and 3-isobuty…
author: Charles, Mélissa Stéphanie
language: English
keywords: Microbiology, Molecular Genetics, Hypoxia-Ischemia; Brain -- physiopatholog; Central Nervous System -- drug effects; Brain Infarction -- drug therapy; Blood-Brain Barrier; Pituitary-Adrenal System; Adrenocorticotropic Hormone; Hypothalamic Hormones; Granulocyte-Colony Stimulating Factor; Receptors, Cytokine; Immunity; Cellular -- drug effects; Enzyme-Linked Immunosorbent Assay; Animals; Newborn Rats; Sprague-Dawley; Analysis of Variance
date published: 2012-06-01T07:00:00Z
date modified: 2026-07-24T02:54:17Z
provider: Loma Linda University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Loma Linda University