Progressive cardiovascular autonomic dysfunction in rats with evolving metabolic syndrome

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Research
• Metabolic Disease Models

Background:

• Metabolic syndrome is associated with increased cardiovascular mortality, potentially due to cardiac sympatho-vagal imbalance.
• Autonomic nervous system (ANS) changes during metabolic syndrome development are not well-characterized.
• Evaluating temporal autonomic modulation is crucial for understanding metabolic syndrome progression.

Purpose of the Study:

• To investigate temporal changes in cardiovascular autonomic modulation during the development of metabolic syndrome in an animal model.
• To compare autonomic control in monosodium glutamate-induced metabolic syndrome rats with control and hypertensive groups.

Main Methods:

• Utilized a monosodium glutamate-induced metabolic syndrome rat model (MetS), comparing them to Wistar-Kyoto (C) and saline-treated SHR (H) rats.
• Assessed Lee index, insulin resistance, and autonomic control via spectral analysis of heart rate variability (HRV) at 3, 6, and 9 months.
• Analyzed systolic arterial pressure variability and the LF/HF index to quantify sympatho-vagal balance.

Main Results:

• MetS rats exhibited higher visceral fat, Lee index, and arterial pressure compared to controls at all ages.
• Heart rate variability (HRV) was reduced in MetS and H groups at 3 and 9 months versus controls.
• Significant alterations in HRV components (LF, VLF) and LF/HF index indicated progressive autonomic dysfunction, particularly pronounced by 9 months.

Conclusions:

• Metabolic syndrome and hypertension in rats develop with progressive autonomic dysfunction, worsening over time.
• Specific autonomic derangements occur early in the development of metabolic syndrome.
• Findings suggest early autonomic imbalance contributes to the cardiovascular risks associated with metabolic syndrome.