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The Hypothalamopituitary-adrenal axis and alcohol preference Matthew J. O’Callaghan, Adam P. Croft, Catherine Jacquot, Hillary J. Little Presented by Muharema Mustic
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Hypothalamus Pituitary Gland Adrenal CRF (CRH) ACTH Corticosterone
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Introduction Hypothalamic-pituitary adrenal (HPA) hormones play a role in drug dependence stress increases alcohol consumption i.e. altering stress hormones increases EtOH preference
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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?”
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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
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Adrenalectomy Experiments Male Wistar Rats Alcohol and Water Adrenalectomy Alcohol preference Experiment 1: Corticosterone, Dexamethasone, Blank
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Removing Corticosterone (B) reduces EtOH intake AdX AdX + B AdX + Dex Sham
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Corticosterone effects EtOH intake
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Back to O’Callaghan Paper HPA axis involved in alcohol preference? – to what extent do drugs influence preference? – How do drugs raise alcohol preference?
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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
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Alcohol Preference Measurements Preference tests preformed on mice individually housed Two fluid bottles available-tap H 2 O and EtOH –Available 24/7 –3 week long period
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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
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Drug Administration RU 38486-glucocorticoid Type II Receptor ant. Spironolactone-glucocorticoid Type I Receptor ant. Metyrapone- inhibits synthesis of corticosterone ACTH1-39- Corticosterone CRF CRF antagonist
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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?
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Experiment 1:Spironolactone and RU38486 One daily intraperitoneal injection to mice of both preference groups – 3 weeks Fluid consumed measured 3x/week
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Mice with a high preference for EtOH are not usually affected Type II Glucocorticoid Receptor Antagonist
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But Low Preference Mice are… Type II GR Antagonist
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Do Glucocorticoids influence Preference? Type II Glucocorticoid Receptor Antagonist
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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
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Corticosterone has an effect
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Metyrapone decreases alcohol intake
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Corticosterone Concentration prior to alcohol preference
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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
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ACTH did not have an effect
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Corticosterone-no effect on low preference mice
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Experiment 4 Corticotropin Releasing Factor (CRF) CRF antagonist Low and high preference groups –Intracerebroventricular injection
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Alpha-helical CRF does not induce higher intake
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Alpha-helical CRF and low preference mice group
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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
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Discussion Spironolactone –No change in either group Metyrapone –Decreased alcohol consumption –metyrapone inhibits synthesis of glucocorticoids
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Discussion ACTH and CRF administration- no change on alcohol preference Alpha-helical CRF (antagonist)- brief increase in intake in low preference mice
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Conclusion Corticosterone influences drinking preferences CRF activity perhaps neuronal?
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Thank You!
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