Retinohypothalamic projections and immunocytochemical analysis of the suprachiasmatic region of the desert iguana Dipsosaurus dorsalis.
Two separate and distinct retinal projections to the hypothalamus in the iguanid lizard Dipsosaurus dorsalis were described using horseradish peroxidase and cobalt-filling techniques. Both of the projections were unilateral and completely crossed; one terminated in the supraoptic nucleus and the other in the suprachiasmatic nucleus. Immunocytochemical analysis showed that the supraoptic nucleus contained cell bodies and fibers that cross-react with antibodies raised against arginine vasopressin, while the suprachiasmatic nucleus contained arginine vasopressin-like immunoreactive fibers emanating from cells in the nearby paraventricular nucleus. The suprachiasmatic nucleus contained a dense plexus of fibers that cross-reacted with neuropeptide-Y antibody. Antiserum against vasoactive intestinal polypeptide showed no reactivity in any part of the forebrain, while antiserum against serotonin showed sparse and uniform reactivity throughout the forebrain, including the suprachiasmatic nucleus. These results, together with other data, indicate that the suprachiasmatic nucleus of D. dorsalis is homologous to the suprachiasmatic nuclei of rodents, structures known to contain circadian pacemakers. We suggest that the suprachiasmatic nucleus may play a similar role in the circadian system of D. dorsalis.
Janik
D
D
Department of Biology, University of Oregon, Eugene 97403.
Cassone
V M
VM
Pickard
G E
GE
Menaker
M
M
D000344:Afferent Pathways; D000818:Animals; D001127:Arginine Vasopressin / Q000032:analysis / Q000276:immunology; D002940:Circadian Rhythm; D005260:Female; D007076:Iguanas / Q000033:anatomy & histology*; D007124:Immunoenzyme Techniques; D008297:Male; D009478:Neuropeptide Y / Q000032:analysis / Q000276:immunology; D009562:Nissl Bodies; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000737:chemistry; D012701:Serotonin / Q000032:analysis / Q000276:immunology; D013194:Staining and Labeling; D013493:Suprachiasmatic Nucleus / Q000033:anatomy & histology* / Q000737:chemistry; D013495:Supraoptic Nucleus / Q000033:anatomy & histology* / Q000737:chemistry; D014660:Vasoactive Intestinal Peptide / Q000032:analysis / Q000276:immunology
D009478:Neuropeptide Y; D001127:Arginine Vasopressin; D012701:Serotonin; D014660:Vasoactive Intestinal Peptide