Lecture Notes on Epigenetics and Environmental Influence

Introduction

• Discussion began in Madrid with Michael Meany from McGill about his work on mother rats and their pups.
  • Different licking behaviors in mother rats lead to different adult rat behaviors.

Hypothesis and Experiment

• Hypothesized whether behavior or genetics caused stress differences in rats.
• Conducted cross-fostering experiments to determine influence.
  • Results: Rearing environment, not genetic mother, impacted adult behavior.

Epigenetics Overview

• Focus on how genes are chemically marked during embryogenesis.
• Epigenetic changes dictate gene expression in various tissues.
• Proposed that maternal behavior reprograms offspring genes epigenetically.
• Found biochemical cascades translating maternal care to DNA programming.

Evolutionary Implications

• DNA is ancient; doesn't indicate geographic or social conditions at birth.
• Early life signals may inform offspring about potential environmental conditions.
• Preparation for life scenarios could become maladaptive in modern environments, e.g., obesity from food abundance.

Human and Primate Studies

• Ethical constraints in human testing lead to primate studies.
• Monkeys: Rearing without mothers leads to behavioral and epigenetic differences.
• Social Status: Birth affects epigenetic changes and health outcomes.

Natural Experiments in Humans

• Ice Storm of 1998: Impact of maternal stress on child health.
• Increased stress correlated with higher autism, metabolic, and autoimmune diseases.

Reprogramming Possibilities

• If genes can be programmed by experience, they might also be reprogrammed.
• Cocaine Addiction Model: Examined potential for deprogramming addiction.
  • Epigenetic drugs modified DNA methylation to alter addiction behaviors.

Epigenetic Insights

• DNA as a dynamic and interactive narrative, not a fixed script.
• Experiences can alter epigenetic marks, allowing potential disease intervention.

Conclusion

• DNA comprises two layers: the fixed genetic sequence and dynamic epigenetic marks.
• Epigenetic changes offer hope for disease treatment and personal responsibility.
• Emphasizes potential control over genetic destiny.

Key Message

• While genes influence us, epigenetic mechanisms provide a degree of freedom in determining outcomes and health prospects.