Transcript Muharema Mustic

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
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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
Corticosterone effects EtOH intake
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
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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
Drug Administration
RU 38486-glucocorticoid Type II Receptor ant.
Spironolactone-glucocorticoid Type I Receptor
ant.
Metyrapone- inhibits synthesis of corticosterone
ACTH1-39Corticosterone
CRF
CRF antagonist
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
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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
Corticosterone has an effect
Metyrapone decreases alcohol
intake
Corticosterone Concentration prior to
alcohol preference
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
ACTH did not have an effect
Corticosterone-no effect on low
preference mice
Experiment 4
• Corticotropin Releasing Factor (CRF)
• CRF antagonist
• Low and high preference groups
– Intracerebroventricular injection
Alpha-helical CRF does not induce higher
intake
Alpha-helical CRF and low preference
mice group
Discussion
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Stress hormones are not involved in the
underlying preference response in high
or low preference mice
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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?
Thank You!