Distribution of hypothalamic, hippocampal and other limbic peptidergic neuronal cell bodies giving rise to retinopetal fibers: Anterograde and retrograde tracing and neuropeptide immunohistochemical studies

• Published in: Neuroscience 2006-01, Vol.140 (3), p.1089-1100
• Main Authors: Vereczki, V., Köves, K., Csáki, A., Grósz, K., Hoffman, G.E., Fiskum, G.
• Format: Article
• Language: English
• Subjects: Animals; Axonal Transport - physiology; Biological and medical sciences; Biotin - analogs & derivatives; Dentate Gyrus - cytology; Dentate Gyrus - metabolism; Dextrans; Efferent Pathways - cytology; Efferent Pathways - metabolism; Fundamental and applied biological sciences. Psychology; Gonadotropin-Releasing Hormone - metabolism; Habenula - cytology; Habenula - metabolism; Hippocampus - cytology; Hippocampus - metabolism; Hypothalamus - cytology; Hypothalamus - metabolism; Immunohistochemistry; LHRH; Limbic System - cytology; Limbic System - metabolism; limboretinal pathway; Male; Neuropeptides - metabolism; Olfactory Pathways - cytology; Olfactory Pathways - metabolism; PACAP; Pituitary Adenylate Cyclase-Activating Polypeptide - metabolism; Presynaptic Terminals - metabolism; Presynaptic Terminals - ultrastructure; Rats; Rats, Sprague-Dawley; Retina - cytology; Retina - metabolism; Stilbamidines; tracing; Vasoactive Intestinal Peptide - metabolism; Vertebrates: nervous system and sense organs; VIP
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2006.02.081

In our present work utilizing the retrograde or anterograde transport of tracers (biotinylated dextran amine and Fluorogold, respectively) we have provided direct evidence for the cells of origin of the limboretinal pathway in rats and their termination in the retina using light microscopic approach. Administration of biotinylated dextran amine into the vitreous body resulted in nerve cell body labeling in several structures: the supraoptic and paraventricular nuclei, the hippocampus (CA1, CA3), the dentate gyrus, the indusium griseum, the olfactory tubercle, and the medial habenula, all of them belong to the limbic system. We estimated that the total number of retrogradely labeled cells is 1495±516. We have seen fiber labeling in the retinorecipient suprachiasmatic nucleus and in the primary visual center, the lateral geniculate body, but labeled nerve cell bodies in these structures were never seen. Iontophoretic application of Fluorogold into the hippocampal formation, where the major part of the biotinylated dextran amine-labeled cell bodies was observed, resulted in labeled fibers in the optic nerve and in the retina indicating that the retrogradely labeled cells in the hippocampus and the dentate gyrus among others are the cells of origin of the centrifugal visual fibers. Sections showing biotinylated dextran amine labeling were stained for vasoactive intestinal polypeptide, pituitary adenylate cyclase activating polypeptide or luteinizing hormone-releasing hormone immunoreactivity using immunohistochemistry. Some biotinylated dextran amine-labeled cells also showed vasoactive intestinal polypeptide, pituitary adenylate cyclase activating polypeptide or luteinizing hormone-releasing hormone immunoreactivity. We conclude that the limboretinal pathway exists and that the cells of origin are partially vasoactive intestinal polypeptide, pituitary adenylate cyclase activating polypeptide or luteinizing hormone-releasing hormone immunoreactive.