Aging affects GABAergic function and calcium homeostasis in the mammalian central clock

Area of Science:

• Neuroscience
• Chronobiology
• Aging Research

Background:

• Aging impairs the suprachiasmatic nucleus (SCN), the mammalian central circadian clock.
• This impairment reduces the SCN's output signal, weakening physiological rhythms like sleep-wake cycles.
• Reduced SCN signal amplitude is linked to decreased synchrony among SCN neurons.

Purpose of the Study:

• To investigate the role of the excitation/inhibition (E/I) balance in SCN neuronal synchronization.
• To test the hypothesis that E/I balance changes contribute to age-related SCN dysfunction.

Main Methods:

• Calcium (Ca2+) imaging was used to study SCN slices from young and old mice.
• The polarity of Ca2+ transients in response to GABA stimulation was analyzed.
• Baseline intracellular Ca2+ concentration was measured in SCN neurons.

Main Results:

• GABAergic excitation and the overall E/I balance were higher in aged SCN neurons compared to young controls.
• Aged SCN neurons exhibited elevated baseline intracellular Ca2+ levels, indicating altered Ca2+ homeostasis.
• These findings suggest a shift in the E/I balance and impaired Ca2+ regulation in the aged SCN.

Conclusions:

• Changes in GABAergic function and Ca2+ homeostasis in SCN neurons may underlie altered network synchrony with aging.
• The study identifies potential mechanisms contributing to the decline in circadian rhythmicity during aging.
• Understanding these age-related SCN changes is crucial for addressing circadian disruption in older populations.