Alcoholic Cardiomyopathy

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Alcoholic Cardiomyopathy

• By,
• Atman Shah
• shahatma_at_msu.edu

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Introduction

• 1. Understanding alcohol metabolism in the human
  body
• 2. Research paper studying the effects of excess
  metabolic byproducts on the heart

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Alcohol Metabolism-1

• Ethanol is absorbed in the stomach and the
  intestine and enters the blood.
• In the liver and heart, an enzyme called alcohol
  dehydrogenase (ADH) converts alcohol to
  acetaldehyde.
• Acetaldehyde is approximately 30 times more toxic
  than alcohol, acetaldehyde is a major cause of
  alcohol-associated side effects. (Drunkenness,
  hangovers)

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Alcohol Metabolism-2

• Acetaldehyde is rapidly converted to acetate by
  other enzymes.
• Acetate (acetic acid) is is eventually
  metabolized to carbon dioxide and water.

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Research Article
Published in Journal of Pharmacology and
Experimental Therapeutics Date August 3, 1999
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Purpose of This Study
To show that acetaldehyde overproduction causes
Alcoholic Cardiomyopathy (ACM) The
acetaldehyde overproduction is artificially
produced by altering genes (transgenic) in mice.
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Methods and Results

• Develop transgenic mice
• Analysis of transgene expression
• Chronic treatment of mice with ethanol
• Study the effects on the heart

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Develop Transgenic Mice

• The genes responsible for transcribing Alcohol
  Dehydrogenase (ADH) are altered to produce more
  ADH
• (Alcohol is converted into acetaldehyde by ADH)
• The MyADH transgene was produced by replacement
  of the catalase coding sequence in the transgene
  MyCAT with the coding sequence for rat ADH

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Analysis of Transgene Expression

• FVB are normal (non-transgenic) mice
• Line 239 and 258 both show high enzyme activity
• Line 239 is selected for the study since it also
  shows a better color coat, useful for
  identification.

• Figure 1
• Shows expression of the transgene compared to
  normal mice.
• Level of expression is measured by enzyme
  activity.

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Analysis (Cont)

• Figure 2 Shows rRNA isolated from various
  tissues probed with a fragment specific to the
  transgene product.
• Multiple Northern blots of different transgenic
  tissue identified the expression of the MyADH
  transgene ONLY in the heart.

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Will These Mice Really Work in the Study?

• I.P. injection of 3g/kg alcohol
• Amount of acetaldehyde in the mice was detected
  using gas chromatography.

Figure 3 Shows that transgenic mice have 4 times
more acetaldehyde than control mice.
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Chronic Treatment of Mice With Ethanol

• The animals were initiated on a 1 alcohol (by
  volume) liquid diet for 10 weeks.
• The quantity of alcohol was gradually increased
  to 4.
• After 10 weeks the mice were sacrificed and their
  hearts were studied.

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Effects on the Heart

• Increased expression of
• Alpha-skeletal actin (SkActin) and
• Atrial Natriuretic factor (ANF)
• (Provide a sensitive indicator of cardiac damage
  in cardiomyopathies)

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Indicators of Cardiac Damage (1)

• Figure 4
• Shows that levels of mRNA of both SkActin and
  ANF were significantly increased in alcohol
  treated mice.

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Indicators of Cardiac Damage (2)

• After 5-months on an alcohol diet mouse hearts
  had enlarged.
• There was a more dramatic cardiac enlargement in
  transgenic mice.
• Heart-to-Body ratio increased to 18 in control
  mice and 80 in transgenic mice.

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Indicators of Cardiac Damage (3)

• Electron microscopy revealed morphological
  changes in the myocardium of alcohol-treated
  mice.
• Normal mice that were treated showed mild effects
  such as sarcoplasmic edema.
• Transgenic mice showed more global effects such
  as
• Loss of sarcoplasmic reticulum
• Degenerated and/or smaller mitochondria
• Disorganized cristae in mitochondria

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Electron Microscopy

• A and C are not treated with alcohol (control)
• B and D are treated with alcohol
• C and D are taken from transgenic mice

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Indicators of Cardiac Damage (4)

• A pressure transducer was used to measure
  contractility.

• Figure 7
• 18-weeks of alcohol diet reduced the
  contractility in both control and transgenic
  mice.

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Conclusion
Increased acetaldehyde exposure to the myocardium
produced alcoholic cardiomyopathy in mice.

• Future research
• Trying to produce transgenic mice that have
  excess acetaldehye dehydrogenase, to protect the
  heart from the damaging effects of acetaldehyde.