Immortal time: Circadian clock properties of rat suprachiasmatic cell lines

Cell lines derived from the rat suprachiasmatic nucleus (SCN) were screened for circadian clock properties distinctive of the SCN in situ. Immortalize d SCN cells generated robust rhythms in uptake of the metabolic marker 2-de oxyglucose and in their content of neurotrophins. The phase relationship be tween these rhythms in vitro was identical to that exhibited by the SCN in vivo. Transplantation of SCN cell lines, but not mesencephalic or fibroblas t Lines, restored the circadian activity rhythm in arrhythmic, SCN-lesioned rats. Thus, distinctive oscillator, pacemaker, and clock properties of the SCN are not only retained but also maintained in an appropriate circadian phase relationship by immortalized SCN progenitors.