Neuropeptidergic organization of the suprachiasmatic nucleus in the blind mole rat (Spalax ehrenbergi)

Julia Negroni, Eviatar Nevo, Howard M. Cooper

Research output: Contribution to journalArticlepeer-review


The blind mole rat, Spalax, is a subterranean rodent with atrophied, subcutaneous eyes. Whereas most of the visual system is highly degenerated, the retino-hypothalamic pathway in this species has remained intact. Although Spalax is considered to be visually blind, circadian locomotor rhythms are entrained by the light/dark cycle. In the present study we used anterograde tracing techniques to demonstrate retinal afferents to the suprachiasmatic nucleus (SCN) and immunohistochemistry to examine the distribution of neuropeptides that are known to be involved in the regulation or expression of circadian rhythmicity. Based on the localization of retinal afferents and neuropeptides, the SCN can be divided into two subdivisions. The ventral region, which receives retinal afferents, also contains vasoactive intestinal polypeptide (VIP)-containing neurons, and fibers that are immunopositive to neuropeptide Y (NPY) and serotonin (5-HT). The dorsal region contains vasopressinergic neurons, but this latter cell population is extremely sparse compared to that described in other rodents. The dorsal region is also characterized by numerous VIP-immunoreactive fibers. The presence of NPY and 5-HT fibers suggests that the SCN receives afferent projections from the intergeniculate leaf-let and from the raphe nuclei, respectively. These neuroanatomical results, together with previous studies of behavior, visual tract tracing, and immediate early gene expression, confirm that an endogenous clock and the capacity for light entrainment of circadian rhythms are conserved in the blind mole rat.

Original languageEnglish
Pages (from-to)633-639
Number of pages7
JournalBrain Research Bulletin
Issue number5
StatePublished - 1997

Bibliographical note

Funding Information:
We would like to thank Christel Merrouche for help with histology, and Ghislaine Claine for care of the animals. The research was funded by grants from Human Frontier (RG95/68), NATO (#950334), ENP (#185), and BIOMED2 (PL/962327).


  • Circadian system
  • Immunohistochemistry
  • Neuroanatomy
  • Neuropeptide Y
  • Rodent
  • Serotonin
  • Subterranean mammal
  • Vasoactive intestinal polypeptide
  • Vasopressin

ASJC Scopus subject areas

  • General Neuroscience


Dive into the research topics of 'Neuropeptidergic organization of the suprachiasmatic nucleus in the blind mole rat (Spalax ehrenbergi)'. Together they form a unique fingerprint.

Cite this