Circadian variations of noradrenaline, 5-hydroxytryptamine and dopamine in specific brain areas of C57Bl/6 and BALB/c mice.

Daily variations in noradrenaline, 5-hydroxytryptamine and dopamine turnover were evident in two strains of mice (C57Bl/6 and BALB/c) subjected to 12-12 h light-dark cycles. These fluctuations were also evident under continuous light (L-L) in C57Bl/6 mice only, a strain which is characterized by clear-cut circadian wheel running activity in the absence of external synchronizers.