Pharmacogenetic Approaches to the Treatment of Alcoholism: Preclinical Studies

Transcription

1 Pharmacogenetic Approaches to the Treatment of Alcoholism: Preclinical Studies Dr. Yedy Israel Departament of Pharmacological and Toxicological Chemistry and Programme of Molecular and Clinical Pharmacology Universidad de Chile,

2 The research team: María Elena Quintanilla, Eduardo Karahanian, Lutske Tampier, Mario Rivera-Meza, Paola Morales, Mario Herrera-Marschitz, Yedy Israel,

3 Identical vs Fraternal twins Factors that influence the Probability of Developing Alcoholism Children adopted at an early age. SNPs in the genome of affected families Genetic protection in Asians: AVERSION 60% Genetics 40% Psychosocial Price Availability Laws Permissiveness Recognition of Risk

4 ONCE ALCOHOLISM HAS DEVELOPED it is maintained by: Positive Reinforcement (rewarding effects and no aversive effects) Negative reinforcement (reducing withdrawal symptomatology) Conditioning (situational) (memory, stress: Craving )

5 TREATMENT DEALS MOSTLY WITH: Positive Reinforcement (reduce rewarding effects; increase aversive effects) Negative reinforcement (reducing withdrawal symptomatology) Conditioning (situational) (memory, stress: Craving )

6 ANIMAL MODELS FOR ALCOHOLISM THERAPIES Positive Reinforcement (increase aversive effects: reduce rewarding effects) Conditioning (situational) (Memory, stress, psychotherapy)

7 Metabolism of Alcohol Deshidrogenasa alcohólica ADH Aversive Reaction Deshidrogenasa aldehídica ALDH2 CH 3 CH 2 OH CH 3 CHO CH 3 COO - ACETALDEHÍDO Disulfiram NAD + NADH NAD + NADH

8 Alcohol Dehydrogenase ADH Aversive Reaction 30% of Asians Aldehyde Dehydrogenase ALDH2 CH 3 CH 2 OH CH 3 CHO CH 3 COO - NAD + NADH NAD + NADH NATURE s DISULFIRAM: Inactivating mutation of ALDH2: an effect analogous to that of disulfiram Reduction of Alcoholism prevalence inasia: ALDH2 +/- = - 67% ALDH2 -/- = - 99%

9 >5 unidades de bebida/ocasión ALCOHOL ABUSE IN NORTH AMERICAN STUDENTS HAVING ASIAN PARENTS ABUSO DE ALCOHOL % % % ALDH+/+ ALDH+/- ALDH-/-

10 Consumo de Alcohol (ml /kg/día) ) Selective breeding of RATS : UChA (abstainers) y UChB (bibulous) 10 Alcohol (10%) and water available 24 hours/day Ratas UChB Aldh2*1/Aldh2*1 Drinker rats Chile, Finland, USA, Italy (Equivalent 1 liter whiskey day) 2 1 Ratas UChA Aldh2*2/Aldh2* Días

11 Acetaldehído arterial (mm) ABSTAINER RATS ALSO SHOW ELEVATIONS IN BLOOD ACETALDEHYDE LEVELS WHEN ADMINISTERED ETHANOL UChA rats UChB rats Etanol (1g/kg) Minutos

12 Antisense molecules bind to the mrna like a magnet, blocking the gene message Gene coded anti ALDH2 mrna ALDH2 is not produced

13 Generation of an Adenoviral Vector carrying an anti-aldh2 antisense gene (Troyan Horse) E1 FIBER PENTON NUCLEUS DNA HEXON Liver specific 70nm ITR Y anti-aldh2 antisense Adenoviral genes E2-L4 ITR

14 Preferential entry of Adenoviral vectors into liver cells (hepatocytes) Fenestra: (pores) nm. Adenovirus: 70 nm ; Other capillaries: <20nM Micrograph of Robin Fraser, University of Otago, New Zealand)

15 Arterial acetaldehyde (µm) ADH2 activity (nmol/min/mg) Effect of i.v antisense gene anti ALDH2 on ALDH2 activity and blood acetaldehyde Arterial acetaldehyde following Ethanol 1g/kg i.p. Liver ALDH2 activity p<0,02 * p<0,01 ** AdV-AS p<0,01 ** NS 15,0 12,5 10,0 40 7,5 20 Viral vehicle 5,0 2,5 p<0,002 ** Minutes 0 AdV-control AdV-AS ethanol

16 UChB rats allowed alcohol consumption for two months. Antisense anti ALDH2 generated by adenovirus (AdVcDNA ALDH2-AS) AdV-Aldh2-AS AS 2 months 35 days Free access to alcohol (10%) and water Happy hour 10% 3 días alcohol and water Without alcohol

17 One-Hour Alcohol Consumption (g/kg/h) Proof of Principle: Happy-hour by alcohol-dependent UChB rats (after 2 months of ethanol free choice) 1.6 AdV-control %; p<0.001 AdV-anti ALDH Days

18 Acetaldehyde : A NEW FRONTIER Reward: Acetaldehyde in the CNS Acetaldehyde Acetaldehyde Acetaldehyde produced in the liver Aversion:

19 Does Acetaldehyde cross the blood-brain barrier? NO: ALDH2 ALDH2 Acetaldehyde ALDH2 At the levels of acetaldehyde present in blood, the enzyme ALDH2 in the tightjunction endothelial cells of brain capillaries oxidizes acetaldehyde into acetate

20 Acetaldehyde : A NEW FRONTIER Reward: Acetaldehyde in the CNS Acetaldehyde Acetaldehyde Acetaldehyde produced in the liver Aversion:

21 acetaldehyde The dopaminergic neurons in the ventral tegmental area project neuronal axons into the nucleus accumbens releasing dopamine

22 The other side of the Coin Recent literature indicates that in the brain acetaldehyde is not aversive but rather reinforcing Rat bred as alcohol drinkers (Indianapolis P rats) will self-administer acetaldehyde into the dopaminergic neurones of the ventral tegmental area of the brain (VTA): (Concentration needed to promote self administration) Ethanol 0.02 M Acetaldehyde M Rodd et al, Alcoholism Clinical and Experimental Research 2005; 2008

23 Is ethanol metabolized into acetaldehyde in the brain? H 2 O 2 H 2 O YES Catalase 70% NAD + NADH ADH Ethanol Acetaldehyde Acetate ALDH NAD + NADH 10-20% CYP2E1 O NADPH NADP H 2 O Although there is no alcohol dehydrogenase in the brain, catalasa and CYP2E1 present in the brain are able to metabolize ethanol. There is also an active brain aldehyde dehydrogenase. Then lets (a) lower the activity of catalase or (b) increase activity of aldehyde dehydrogenase

24 Injection of Lentiviral Vector (gutless) shrna anticatalase Lenti Dopaminergic neurones (VTA) H 2 O 2 H 2 O Catalase NAD + NADH ADH Ethanol Acetaldehyde Acetate ALDH NAD + NADH Inhibition of catalase synthesis by microinjection of Lentiviral vector coding for shrna anticatalase into the VTA CYP2E1 O NADPH NADP H 2 O

25 Acetaldehyde (nomoles/h/mg wet tissue) Inhibition of Brain Catalase( VTA) by stereotaxic administration of an anti-catalasa viral vector * 0 n=4 n=4 Control- Lenti 1 Anticatalase- Lenti

26 Body Weight (g) Ethanol Intake (g/kg/day) Inhibition of alcohol consumption by inhibition of brain acetaldehyde synthesis (lowering catalase synthesis) A Control-Lenti 3 2 Anticatalase-Lenti B Days Anticatalase-Lenti 200 Control-Lenti Days

27 Dopamine efflux in nucleus accumbens (% of control) Ethanol 1g/kg (i.p.) A P < 0.05 Anticatalase Lentiviral vector specifically blocks the liberation of dopamine in Nucleus Accumbens Control-Lenti B D-amphetamine (0.1 mm) 600 Anticatalase-Lenti NS Control-Lenti C KCl (100 mm) 300 Anticatalase-Lenti NS Karahanian E et al epub 2011 Control-Lenti Anticatalase-Lenti

28 Ethanol intake (g/kg/day) Inhibition of alcohol consumption by activation of brain acetaldehyde elimination (by increasing aldehyde de dehydrogenase synthesis) 9,00 8,00 ALDH2 empty virus Control vector 7,00 6,00 5,00 4,00 3,00 2,00 1,00 Aldehyde dehydrogenase vector (ALDH2) 0, TIME (days) Manuscript in preparation 2012

29 TREATMENT DEALS MOSTLY WITH: Positive Reinforcement (increasing aversive effects or reduce rewarding effects; ) Conditioning (situational) (memory, stress: Craving )

30 24 Hours Ethanol Intake (g/kg/day) Partial extinction of conditioning is needed to observe the inhibitory effect of the anticatalase lentiviral vector on ethanol intake. 9 Anticatalase -Lenti Lentiviral Vector Control Control-Lenti -lenti Partial extinction of conditioning 3 Anticatalase-Lenti week alcohol deprivation Days

31 TOTAL ETHANOL (20% + 10%) INTAKE (g/kg/h) TOTAL ETHANOL (20% + 10%) INTAKE (g/kg/h) A Control Lenti * * Effect of Anticatalase on the Alcohol deprivation effect (ADE) happy hour deprivation deprivation 0 60 days Baseline Re-Exposure Re-Exposure N.S. < < B * * days Anticatalase Lenti deprivation deprivation Baseline Re-Exposure Re-Exposure 80% inhibition of binge drinking by brain (VTA) anticatalase

32 GENE DELIVERY CONCLUSIONES TO TREAT ALCOHOLISM FROM PRECLINICAL STUDIES 1. Inhibit acetaldehyde degradation. By reduction of liver aldehyde dehydrogenase gene expression (duración 30 days-1 year) 2. Reduce brain catalase synthesis by gene delivery. Inhibition of brain acetaldehyde generation. 3. Increase brain aldehyde dehydrogenase synthesis by gene delivery. Activation of brain acetaldehyde degradation 4. Reduce conditioning and memory of reward (added to the above).

33 Agradecimientos Financiamiento: NIH, Fondecyt, Instituto Milenio ICDB