Acute baroreceptor unloading evokes Fos expression in anesthetized rat brain

Area of Science:

• Neuroscience
• Cardiovascular Physiology

Background:

• The baroreceptor reflex is crucial for maintaining blood pressure homeostasis.
• Understanding the central neural pathways involved is essential for managing cardiovascular disorders.

Purpose of the Study:

• To investigate the functional organization of brain pathways responding to the baroreceptor reflex.
• To identify specific brain regions activated by acute baroreceptor unloading.

Main Methods:

• Mapping Fos protein immunoreactivity in anesthetized rats.
• Utilizing sinoaortic denervation (SAD) to acutely unload baroreceptors.
• Comparing Fos expression patterns between SAD, control, and sham operation groups.

Main Results:

• Sinoaortic denervation (SAD) induced a distinct Fos expression pattern in the nucleus tractus solitarii (NTS).
• Fos expression was also prominent in the rostral ventrolateral medulla (RVLM), lateral parabrachial nucleus (LPBN), hypothalamic paraventricular nucleus (PVN), supraoptic nucleus (SON), and central amygdaloid nucleus (CeA).
• These activated regions receive direct or indirect input from the NTS.

Conclusions:

• Identified specific brainstem and forebrain regions responsive to decreased arterial baroreceptor activity.
• Demonstrated the utility of Fos mapping for delineating neural pathways of the baroreceptor reflex.
• Provided insights into the central neural circuitry regulating blood pressure independent of stress or arousal.