摘要：The hypothalamic suprachiasmatic nucleus (SCN), the central circadian pacemaker in mammals, undergoes serotonergic regulation, but the underlying mechanisms remain obscure. Here, we generated a subclone of an SCN progenitor cell line expressing Ca2+ sensors (SCN2.2YC) and compared its 5-HT receptor signalling with that of rat SCN neurons in brain slices. SCN2.2YC cells expressed 5-HT1A/2A/2B/2C, but not 5A/7, while all six subtypes were expressed in SCN tissues. High K+ or 5-HT increased cytosolic Ca2+ in SCN2.2YC cells. The 5-HT responses were inhibited by ritanserin and SB-221284, but resistant to WAY-100635 and RS-127445, suggesting predominant involvement of 5-HT2C for Ca2+ mobilisations. Consistently, Ca2+ imaging and voltage-clamp electrophysiology using rat SCN slices demonstrated post-synaptic 5-HT2C expression. Because 5-HT2C expression was postnatally increased in the SCN and 5-HT-induced Ca2+ mobilisations were amplified in differentiated SCN2.2YC cells and developed SCN neurons, we suggest that this signalling development occurs in accordance with central clock maturations.
