The substructure of the suprachiasmatic nucleus: Similarities between nocturnal and diurnal spiny mice

Rotem Cohen*, Noga Kronfeld-Schor, Chidambaram Ramanathan, Anna Baumgras, Laura Smale

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Evolutionary transitions between nocturnal and diurnal patterns of adaptation to the day-night cycle must have involved fundamental changes in the neural mechanisms that coordinate the daily patterning of activity, but little is known about how these mechanisms differ. One reason is that information on these systems in very closely related diurnal and nocturnal species is lacking. In this study, we characterize the suprachiasmatic nucleus (SCN), the primary brain structure involved in the generation and coordination of circadian rhythms, in two members of the genus Acomys with very different activity patterns, Acomys russatus (the golden spiny mouse, diurnal) and Acomys cahirinus (the common spiny mouse, nocturnal). Immunohistochemical techniques were used to label cell bodies containing vasoactive intestinal polypeptide (VIP), vasopressin (VP), gastrin-releasing peptide (GRP) and calbindin (CalB) in the SCN, as well as two sets of inputs to it, those containing serotonin (5-HT) and neuropeptide Y (NPY), respectively. All were present in the SCN of both species and no differences between them were seen. On the basis of neuronal phenotype, the SCN was organized into three basic regions that contained VIP-immunoreactive (-ir), CalB-ir and VP-ir cells, in the ventral, middle and dorsal SCN, respectively. In the rostral SCN, GRP-ir cells were in both the VIP and the CalB cell regions, and in the caudal area they were distributed across a portion of each of the other three regions. Fibers containing NPY-ir and serotonin (5-HT)-ir were most concentrated in the areas containing VIP-ir and CalB-ir cells, respectively. The details of the spatial relationships among the labeled cells and fibers seen here are discussed in relation to different approaches investigators have taken to characterize the SCN more generally.

Original languageEnglish
Pages (from-to)9-22
Number of pages14
JournalBrain, Behavior and Evolution
Issue number1
StatePublished - Mar 2010


FundersFunder number
National Institute of Mental HealthR01MH053433


    • Acomys
    • Calbindin
    • Diurnal
    • Gastrin-releasing peptide
    • Neuropeptide Y
    • Nocturnal
    • Serotonin
    • Suprachiasmatic nucleus
    • Vasoactive intestinal polypeptide
    • Vasopressin


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