Age-related changes in large-conductance calcium-activated potassium channels in mammalian circadian clock neurons

作者：Farajnia Sahar; Meijer Johanna H; Michel Stephan^*

来源：Neurobiology of Aging, 2015, 36(6): 2176-2183.

DOI：10.1016/j.neurobiolaging.2014.12.040

• Suprachiasmatic nucleus
• Aging
• Action potential
• Afterhyperpolarization
• Calcium
• Potassium channels

Aging impairs the function of the suprachiasmatic nucleus (SCN, the central mammalian clock), leading to a decline in the circadian rhythm of many physiological processes, including sleep-wake rhythms. Recent studies have found evidence of age-related changes in the circadian regulation of potassium currents; these changes presumably lead to a decrease in the SCN's electrical rhythm amplitude. Current through large-conductance Ca2+-activated K+ (BK) channels promote rhythmicity in both SCN neuronal activity and behavior. In many neuron types, changes in BK activity are correlated with changes in intracellular Ca2+ concentration ([Ca2+](i)). We performed patch-clamp recordings of SCN neurons in aged mice and observed that the circadian modulation of BK channel activity was lost because of a reduction in BK currents during the night. This reduced current diminished the afterhyperpolarization, depolarized the resting membrane potential, widened the action potential, and increased [Ca2+](i). These data suggest that reduced BK current increases [Ca2+](i) by altering the action potential waveform, possibly contributing to the observed age-related phenotype.

• 出版日期2015-6