title: Expression of GAP-43 during development and after monocular enucleation in the rat superior colliculus.
abstract: The retinotectal projection of rodents presents a precise retinotopic organization that develops, from diffuse connections, from the day of birth to post-natal day 10. Previous data had demonstrated that these projections undergo reorganization after retinal lesions, nerve crush and monocular enucleation. The axonal growth seems to be directly related to growth-associated protein-43 (GAP-43) expression, a protein predominantly located in growth cones, which is regulated throughout development. GAP-43 is presented both under non-phosphorylated and phosphorylated (pGAP-43) forms. The phosphorylated form, has been associated to axon growth via polymerization of F-actin, and synaptic enhancement through neurotransmitter release facilitation. Herein we investigated the spatio-temporal expression of GAP-43 in the rat superior colliculus during normal development and after monocular enucleation in different stages of development. Lister Hooded rats ranging from post-natal day 0 to 70 were used for ontogeny studies. Another group of animals were submitted to monocular enucleation at post-natal day 10 (PND10) or PND21. After different survival-times, the animals were sacrificed and the brains processed for either immunohistochemistry or western blotting analysis. Our data show that GAP-43 is expressed in retinotectal axons in early stages of development but remains present in adulthood. Moreover, monocular enucleation leads to an increase in pGAP-43 expression in the deafferented colliculus. Taken together these results suggest a role for pGAP-43 in retinotectal morphological plasticity observed both during normal development and after monocular enucleation.
authors.affiliation: Programa de Neurociências, Departamento de Neurobiologia, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ, Brazil.
authors.forename: Henrique Rocha
authors.initials: HR
authors.lastname: Mendonça
authors.forename: Sheila Espírito Santo
authors.initials: SE
authors.lastname: Araújo
authors.forename: Ana Lucia Tavares
authors.initials: AL
authors.lastname: Gomes
authors.forename: Alfred
authors.initials: A
authors.lastname: Sholl-Franco
authors.forename: Adriana
authors.initials: A
authors.lastname: da Cunha Faria Melibeu
authors.forename: Claudio Alberto
authors.initials: CA
authors.lastname: Serfaty
authors.forename: Paula
authors.initials: P
authors.lastname: Campello-Costa
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D015353:Eye Enucleation; D019922:GAP-43 Protein / Q000096:biosynthesis*; D051381:Rats; D013477:Superior Colliculi / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors; D014795:Visual Pathways / Q000254:growth & development / Q000378:metabolism
chemical_list: D019922:GAP-43 Protein