Control of Blood Pressure Variability Across Behavioral States by Brainstem Adrenergic Neurons

Area of Science:

• Neuroscience
• Cardiovascular Physiology
• Autonomic Nervous System Regulation

Background:

• Short-term blood pressure (BP) variability is a significant predictor of cardiovascular and cerebrovascular risks.
• The central neural mechanisms controlling BP variability across different behavioral states are not well understood.

Purpose of the Study:

• To investigate the role of rostral ventrolateral medulla C1 (RVLM^C1) neurons in regulating short-term BP during sleep-wake transitions and physical activity.
• To determine how arterial baroreflex feedback influences RVLM^C1 neuronal activity.
• To assess the impact of RVLM^C1 neuron function on BP stability.

Main Methods:

• Utilized genetically targeted fiber photometry to record RVLM^C1 neuronal activity in freely behaving rats across various behavioral states.
• Employed sinoaortic denervation to evaluate the contribution of baroreceptor feedback to RVLM^C1 neuron activity.
• Performed selective genetic ablation of RVLM^C1 neurons to ascertain their role in BP regulation.

Main Results:

• RVLM^C1 neurons displayed state-dependent activity, increasing during arousal, sustained during REM sleep, and recruited during physical activity.
• Baroreflex input modulated RVLM^C1 neuron activity in response to BP changes and sleep state transitions.
• Ablation of RVLM^C1 neurons did not affect mean BP but caused significant BP instability during arousal and movement.

Conclusions:

• RVLM^C1 neurons are crucial for stabilizing BP during behavioral state transitions by integrating central arousal signals with baroreceptor feedback.
• Disruption of RVLM^C1 neurons leads to heightened short-term BP variability, suggesting a neural basis for pathological BP instability.