688] Aiming at Alcoholism with Ribozyme Genes: Silencing the mRNA for an Alcohol Detoxifying EnzymePoster Session II: Gene Expression in Animal Model Systems
Protection against alcoholism is provided by a natural aversion to alcohol in certain individuals or by pharmacological intervention in alcoholics.
Ethanol is detoxified by oxidation to acetaldehyde and then to acetate by alcohol dehydrogenase and aldehyde dehydrogenase-2 (ALDH2). Impairment of ALDH2 results in accumulation of acetaldehyde leading to unpleasant physical effects and aversion to ethanol.
This condition is observed in individuals carrying an inactivating mutation in the ALDH2 gene and in alcoholics treated with disulfiram, a nonspecific toxic drug which inactivates ALDH2 by covalent modification. Similar protection might be achieved by diminishing enzyme activity with highly specific ribozymes designed to silence the mRNA for ALDH2.
Hairpin and hammerhead ribozymes targeted to a single region of rat ALDH2 mRNA (nucleotides 1551-1571) were tested in rat hepatoma cells in culture.
The hairpin ribozyme provided a 42 % reduction in the ALDH2 activity, 24 % due to cleavage and 18 % due to antisense action. The combined effects of this hairpin ribozyme amount to 
70 % reduction of the ALDH2 activity when protein half life and lipofection efficiency are taken into account.
In conclusion, a hairpin ribozyme directed to nts 1553-1569 of the rat ALDH2 mRNA is a good candidate for in vivo experiments geared towards developing genetic drugs for alcoholism.
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