Physiological carotid body denervation during aging

Area of Science:

• Physiology
• Cell Biology
• Gerontology

Background:

• Aging is associated with diminished homeostatic capacity.
• The carotid body (CB) is crucial for maintaining homeostasis, particularly in response to oxygen levels.
• The impact of aging on CB synaptic mechanisms remains incompletely understood.

Purpose of the Study:

• To investigate whether aging affects oxygen-sensitive mechanisms in CB cells by reducing synaptic junction contact surfaces.
• To test the hypothesis that the aging CB undergoes a
• physiological denervation
• .

Main Methods:

• Comparative analysis of young (2-3 months) and senescent (22 months) male Wistar rats.
• Transmission electron microscopy to examine CB ultrastructure.
• Immunohistochemical analysis to evaluate expressions of HIF-1α, VEGF, and NOS-1.

Main Results:

• Senescent CBs exhibited decreased expression of HIF-1α, VEGF, and NOS-1.
• Reduced cell volume, fewer mitochondria, and shrunken nuclei were observed in older rats.
• A significant reduction in synaptic connections (from 125 in young to 28 in old rats) was the most notable finding.
• Accumulation of lipofuscin and increased extracellular matrix were also present in aged CBs.

Conclusions:

• The aging carotid body undergoes a
• physiological denervation
• characterized by a significant loss of synaptic connections.
• This reduction in synaptic junctions may contribute to the decreased homeostatic capacity observed in aging.
• The age-related synaptic reduction could be a protective mechanism against reactive oxygen species accumulation.