title: Immunocytochemical characterization of the suprachiasmatic nucleus and the intergeniculate leaflet in the diurnal ground squirrel, Spermophilus lateralis.
abstract: The suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) are retinorecipient structures that play important roles in the expression of circadian rhythmicity. We examined these two structures in a diurnal ground squirrel, Spermophilus lateralis, using immunohistochemical techniques, and cholera toxin-bound horseradish peroxidase. A number of immunoreactive substances are distributed within the ground squirrel SCN in a pattern similar to that reported in many other mammals. These include vasopressin, vasoactive intestinal polypeptide, serotonin, neuropeptide Y (NPY), and glial fibrillary acidic protein. The squirrel SCN differs from that of most other species examined to date in two respects. First, a dense cluster of cells containing immunoreactive L-enkephalin (L-ENK-IR) is observed in the center of the SCN. Second, there is a contralateral, but no ipsilateral, projection from the retina to the SCN. In the lateral geniculate region there is a substantial region that contains NPY-immunoreactive cells and receives a bilateral retinal projection. This region is assumed to be homologous with the IGL described in other mammals. Cells containing L-ENK-IR are distributed throughout the LGN in groups that overlap, but which have a distinctly different distribution than the more extensive groups of NPY-IR cells.
authors.affiliation: Department of Psychiatry, State University of New York, Stony Brook 11794.
authors.forename: L
authors.initials: L
authors.lastname: Smale
authors.forename: J
authors.initials: J
authors.lastname: Blanchard
authors.forename: R Y
authors.initials: RY
authors.lastname: Moore
authors.forename: L P
authors.initials: LP
authors.lastname: Morin
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology; D004745:Enkephalins / Q000378:metabolism; D005260:Female; D005829:Geniculate Bodies / Q000166:cytology / Q000378:metabolism*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D009475:Neurons, Afferent / Q000502:physiology; D009478:Neuropeptide Y / Q000378:metabolism; D012160:Retina / Q000166:cytology; D012589:Sciuridae / Q000378:metabolism*; D012621:Seasons; D012701:Serotonin / Q000378:metabolism; D013373:Substance P / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism
chemical_list: D004745:Enkephalins; D005904:Glial Fibrillary Acidic Protein; D009478:Neuropeptide Y; D014667:Vasopressins; D012701:Serotonin; D013373:Substance P; D014660:Vasoactive Intestinal Peptide