The Hypothalamopituitary-adrenal axis and alcohol preference Matthew J. O’Callaghan, Adam P. Croft, Catherine Jacquot, Hillary J. Little Presented by Muharema Mustic
Hypothalamus CRF (CRH) Pituitary Gland ACTH Adrenal Corticosterone
Introduction • Hypothalamic-pituitary adrenal (HPA) hormones play a role in drug dependence • stress increases alcohol consumption i.e. altering stress hormones increases EtOH preference
Purpose of the Study • “To what extent are the HPA axis components involved in alcohol preference?” • To what extent do agonists and antagonists of the HPA axis have an influence?”
Background Paper • “Consequence of Long-Term Exposure to Corticosterone or Dexamethasone on Ethanol Consumption in the Adrenalectomised Rat, and the Effect of Type I and Type II Corticosteroid Receptor Antagonists” • By Fahlke, C., Hard, E. Eriksson, J.A., Engel, S. Hansen
Adrenalectomy Experiments • Male Wistar Rats • Alcohol and Water • Adrenalectomy • Alcohol preference • Experiment 1: Corticosterone, Dexamethasone, Blank
Removing Corticosterone (B) reduces EtOH intake AdX AdX + B AdX + Dex Sham
Back to O’Callaghan Paper • HPA axis involved in alcohol preference? • to what extent do drugs influence preference? • How do drugs raise alcohol preference?
Materials and Methods • In house bred animals • Housed at ~ 21 degrees Celsius • Housed in single sex groups of 10/cage • Free access to water and rodent chow • 12 hour light/dark cycle • Light phase between 8am-8pm • Dark phase 8pm-8am
Alcohol Preference Measurements • Preference tests preformed on mice individually housed • Two fluid bottles available-tap H2O and EtOH • Available 24/7 • 3 week long period
Alcohol Preference Measurements • Fluid intake measurement made 3x week • Alcohol preference measured • Ratios of last week used to assign categories • High preference mice- ratio of 0.75 and higher • Low preference mice-ratio of 0.34 and lower
Experiment 1 • RU 38486-100mg/kg • Spironolactone-50mg/kg • Purpose of the experiment: 1. Do these two drugs decrease alcohol preference in high preference mice when given for 1 week? 2. Do these drugs prevent increase in preference that was due to vehicle injections that occurred over the 3 week period?
Experiment 1:Spironolactone and RU38486 • One daily intraperitoneal injection to mice of both preference groups • 3 weeks • Fluid consumed measured 3x/week
Mice with a high preference for EtOH are not usually affected Type II Glucocorticoid Receptor Antagonist
But Low Preference Mice are… Type II GR Antagonist
Do Glucocorticoids influence Preference? Type II Glucocorticoid Receptor Antagonist
Experiment 2 • Metyrapone • Intraperitoneal injection • Single and repeated intraperitoneal injections • 100mg/kg • 1 week long for high preference mice • Fluid consumption measured daily • 3 weeks long for low preference mice
Experiment 3 • ACTH1-39 • Tested on low preference alcohol group only • Fluid measured prior to daily after injections started • Administration for 4 days • Once daily • Intraperitoneal injection
Experiment 4 • Corticotropin Releasing Factor (CRF) • CRF antagonist • Low and high preference groups • Intracerebroventricular injection
Discussion • Stress hormones are not involved in the underlying preference response in high or low preference mice • no effect on glucocorticoid receptors of either type • Except central CRF
Discussion • Spironolactone • No change in either group • Metyrapone • Decreased alcohol consumption • metyrapone inhibits synthesis of glucocorticoids
Discussion • ACTH and CRF administration- no change on alcohol preference • Alpha-helical CRF (antagonist)- brief increase in intake in low preference mice
Conclusion • Corticosterone influences drinking preferences • CRF activity perhaps neuronal?