Cell and tissue research
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Cell and tissue research · Oct 2002
Comparative StudyPhenotype of Per1- and Per2-expressing neurons in the suprachiasmatic nucleus of a diurnal rodent (Arvicanthis ansorgei): comparison with a nocturnal species, the rat.
In mammals, the suprachiasmatic nuclei (SCN) are the site of the master circadian pacemaker whose molecular core mechanism is based on interlocking transcriptional/translational feedback loops involving clock genes. Among clock genes, Per1 and Per2 are important for both the maintenance of circadian rhythmicity and entrainment to light cues. Several circadian rhythms (e.g., locomotor activity) present opposite patterns in diurnal and nocturnal species. ⋯ This differential expression of Per1 and Per2 in AVP and VIP neurons is more distinct in A. ansorgei than in the rat. Thus, our data suggest a major role for the dorsomedial part of the SCN in the maintenance of circadian rhythmicity. Furthermore, the similar diurnal pattern of Per1 and Per2 expression in diurnal and nocturnal rodents suggests that the circadian organization of locomotor activity rhythms probably relies on differential cellular integration mechanisms downstream of the clock.