Autonomic nervous system function in identical twins discordant for obesity

Area of Science:

• Cardiovascular physiology
• Autonomic nervous system function
• Obesity research

Background:

• Moderate obesity is prevalent and may influence physiological functions.
• Autonomic nervous system (ANS) regulates involuntary bodily processes.
• Understanding ANS function in obesity is crucial for public health.

Purpose of the Study:

• To investigate the influence of moderate obesity on autonomic nervous function.
• To compare cardiovascular autonomic reflex responses between obese and non-obese individuals within twin pairs.
• To assess the role of genetic factors in autonomic reactivity.

Main Methods:

• Studied nineteen healthy identical twin pairs with a Body Mass Index (BMI) difference of at least 3 kg/m2.
• Utilized standard non-invasive cardiovascular reflex tests and pupillometry.
• Compared heart rate, blood pressure, and pupillary responses between obese (BMI 30±2 kg/m2) and non-obese (BMI 23±1 kg/m2) twins.

Main Results:

• No significant differences were observed in heart rate, blood pressure, or pupillary responses between obese and non-obese twins.
• Strong correlations in autonomic variables were found between lean and obese twins, particularly for parasympathetic function.
• Some correlations were also noted for sympathetic function, suggesting shared genetic influences.

Conclusions:

• Moderate obesity does not significantly affect sympathetic or parasympathetic nervous system responsiveness.
• Genetic factors play a substantial role in determining individual cardiovascular autonomic reactivity.
• Identical twins provide a valuable model for dissecting genetic and environmental influences on autonomic function.