1. Alcohol and Stress Hormones
Hilary J. Little
Institute of Psychiatry,
University of London,
United Kingdom

2. Effects of alcohol i) Acute effects ii) Long term effects - dependence
iii) Interactions with stress hormones 1

3. Alcohol Dependence ? Effect on brain Withdrawal Acute actions normal
range
Tolerance
Relapse 2
Time
Alcohol intake

4. Acute effects of alcohol
Decreases effects of excitatory transmitters, glutamate and aspartate.
- particular effect at NMDA receptors - may be relevant to amnesic actions
Increases effects pf GABA – in some neurons
5-HT transmission altered (?mood changes?) 3

5. Acute effects of alcohol
Increases release of endogenous opiates
Increases mesolimbic dopamine transmission
Activates the hypothalamo-pituitary adrenal system (HPA) 4

6. 2. Compulsion to take drug
Drug dependence
1. Withdrawal symptoms
2. Compulsion to take drug 5

7. The Alcohol Withdrawal Syndrome
Anxiety, irritability
Tremor, convulsions (can be fatal)
Hallucinations, confusion (‘DT’s’) 6

8. Aims of our experiments
i) Neuronal changes during the acute phase of alcohol withdrawal
ii) Long term neuronal changes during alcohol abstinence
iii) Potential new medication approaches:
- glucocorticoid antagonists 7

9. Clinical evidence for importance of glucocorticoids in alcohol dependence
More severe life events (“danger” & “loss”) in years preceding alcohol dependence
“High strain” occupations increase risk for alcohol dependence
Stressful experiences during abstinence increase likelihood of relapse drinking
Stress induces alcohol craving; related to incidence of relapse 8

10. Cognitive deficits in alcoholics
Incidence of cognitive dysfunction in abstinent alcoholics estimated to be 50 to 80%
Difficulties in learning new information, retention over long intervals, problems in executive function
No current effective treatment 9

11. Cognitive deficits in alcoholics
Neuronal damage after long term alcohol consumption:-
frontal association cortex, hippocampus (rodents), thalamus
Preclinical and clinical evidence that withdrawal of alcohol after long term consumption plays an important role in memory deficits
In high concentrations, glucocorticoid stress hormones (cortisol, corticosterone) cause neurotoxicity and cognitive deficits 10

12. Stress and drug dependence
Stress can alter the effects of many drugs
Causes alterations in synaptic plasticity and neuronal survival
Such changes include acute, prolonged and delayed effects
Stress activates the mesolimbic dopamine system 11

13. cortisol (or corticosterone)h e H y p o t h a l a m i c - P i t u i t a r y - A d r e n a l A x i s
The HPA axis `C R F P I T U I T A R Y
ACTH a d r e n a l s
cortisol (or corticosterone) 12

14. Corticosterone in the brain
Type I
(mineralocorticoid) receptors
Type II
glucocorticoid receptors
What effects does corticosterone have on the brain during alcohol withdrawal?
What are the concentrations of corticosterone in the brain?
Why do the concentrations matter? 13

15. VTA Mesolimbic dopamine system nucleus accumben DA
Initial target sites differ, but some common neuronal actions
e.g dopamine release
Mesolimbic dopamine pathway activated by natural rewards
This pathway also activated by stress
NMDA activation
nucleus
accumben
VTA DA
Alcohol, nicotine, opiates
Cocaine, amphetamine 14

16. Effect of corticosterone on firing of ventral tegmental neurones from control animals
Firing rate (Hz) 1 2 3 4 * **
Basal
firing
5 µM
NMDA
15 µM
NMDA
aCSF
Corticosterone 100 nM
*P < 0.05 **P < 0.01 15

17. Corticosterone concentrations in rodent brain
Measured corticosterone concentrations in brain regions in rodents after chronic alcohol consumption
Chronic alcohol treatment and withdrawal
Radioimmunoassay after ethanol/DMSO extraction of brain homogenates
Identity of corticosterone verified by HPLC and GC-MS 16

18. Regional brain concentrations of corticosterone
C57 strain mice
Alcohol drinking for
20 weeks
Samples 6 days after withdrawal
Corticosterone
ng/g ** *
300
250 50
100
150
Blood corticosterone, nM
Total Free
200
150
100 50
Hypoth.
Hipp.
Brain
PFC
Cortex
Striat.
Thal.
Cereb.
stem
When alcohol not withdrawn, no changes in brain corticosterone 17

19. Regional brain corticosterone concentrations
Lister Hooded rats, 8 months drinking, 2 months abstinence 10 20 30 *
Chronic
alcohol
Corticosterone ng/g
Hypoth Hipp Midbrain PFC Cortex Striatum
Plasma concentrations not significantly different
Controls 18

20. Summary: brain corticosterone and alcohol
Chronic alcohol consumption increased brain concentrations of the glucocorticoid, corticosterone
Plasma levels unchanged
Changes seen only after alcohol withdrawal
Largest increases in prefrontal cortex and hippocampus 20

21. Mechanism of brain corticosterone changes after chronic alcohol treatment and withdrawal?
Local synthesis of glucocorticoids suggested to occur outside adrenal glands
Demonstrated in adipose tissue
Occurs via the enzyme 11--hydroxysteroid dehydrogenase (HSD-1)
This enzyme is present in brain 20

22. Relevance of brain glucocorticoid changes?
i) Involved in alcohol-induced brain damage?
ii) Responsible for cognitive deficits after long term
alcohol intake?
iii) Alter feedback mechanisms for control of adrenal
hormone release?
iv) Involved in continued desire to drink alcohol? 21

23. Current drug treatments for alcohol dependence
Naltrexone
Opiate antagonist
Decreases continuation of drinking once relapse occurs
Acamprosate
Mechanism unknown
Sole action apparently to decrease alcohol intake
Disulphiram (“Antabuse”)
Prevents metabolism of acetaldehyde
this accumulates, producing unpleasant symptoms.
- may help those who really want to stop drinking
Effects: 10 – 20% decrease in relapse drinking 22

24. Alcohol withdrawal = window of opportunity?
normal
range
Withdrawal ?
Relapse
Time
Effect
on brain
Alcohol intake 23

25. Alcohol withdrawal = window of opportunity?
Multiple withdrawal episodes, more severe withdrawal, higher risk of relapse, greater cognitive deficits
Evidence cognitive deficits due to withdrawal rather than to direct effects
Acute withdrawal phase offers "window of opportunity" for treatment
Drug studied:-
i) glucocorticoid Type II receptor antagonist –
"mifepristone" 25

26. Effects of Mifepristone on Alcohol
Withdrawal Hyperexcitability in Mice
Vehicle/alcohol withdrawal
Median
response score
Vehicle/control
3 weeks alcohol via
liquid diet
Mifepristone /alcohol withdrawal
Mifepristone/control 1 2 3 4
Injections of vehicle
or mifepristone just
prior to withdrawal
Response to handling
measured 3 4 5 6 7 8 9
Time (h)
Mifepristone, the Type II glucocorticoid receptor antagonist decreased, but did not prevent, alcohol withdrawal hyperexcitability 25

27. Object recognition test26

28. Effects of Mifepristone on Memory Deficit in Mice
after Alcohol Withdrawal - Object Recognition Test
Vehicle/control
22 weeks alcohol via
drinking fluid
Vehicle/alcohol withdrawal
Mifepristone /alcohol withdrawal
Mifepristone/control *
Injections of vehicle
or mifepristone just
prior to withdrawal
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
Difference in time measured between exploration of novel and familiar objects, 1 week after withdrawal
Mifepristone decreased the memory loss seen after withdrawal from chronic alcohol intake 27

29. Effects of Mifepristone on Neuronal Damage in Organotypic Hippocampal Cultures
20X 5X
Propidium iodide fluorescence
Control
Alcohol withdrawal
Corticosterone +
alcohol withdrawal
Mifepristone + corticosterone +
alcohol withdrawal
Spironolactone + corticosterone +
alcohol withdrawal
Corticosterone greatly increased the neuronal damage caused by
withdrawal of alcohol.
Mifepristone, but not spironolactone prevented this effect of
corticosterone 28
Collaboration with University of Kentucky

30. Effects of Type II glucocorticoid receptor antagonist mifepristone (RU38486) on alcohol preference in mice
Alcohol
preference
ratio
Low alcohol
preferring mice
Saline injections
Mifepristone injections
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Choice 8% alcohol
v tap water
Once daily injections of isotonic saline
or Type II receptor antagonist
===
===
===
***
***
*** 2 4 6 8 10 12 14 16 18 20
Day
Slowly developing increase in alcohol preference and consumption
Effect prevented by mifepristone 29

31. Clinical Trial of Mifepristone in Alcoholics
Participants - alcoholics entering the Alcohol Unit for detoxification
Treatment - mifepristone or placebo for two weeks from cessation of drinking
Testing – depression ratings and cognitive test battery (CANTAB) during weeks 3 and 4
Follow-up – 3,6 and 12 months to record relapse drinking 30

32. Mifepristone as a Potential Treatment?
Glucocorticoid Type II receptor antagonist e.g. mifepristone
Reduced withdrawal severity
Reduced memory loss
Prevented neurotoxicity in vitro
Prevent stress-induced increases in alcohol drinking
?effective in alcoholics - study in progress 32

33. Future treatments for drug dependence?
Little research on drug dependence was supported by government funding
1990s
Drug dependence becomes a special target area for research
2000s
Possibility accepted of medication treatment for alcohol dependence
Next?
? Development of effective treatments to prevent dependence and memory loss?