Expression of GAP-43 during development and after monocular enucleation in the rat superior colliculus.
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.
Mendonça
Henrique Rocha
HR
Programa de Neurociências, Departamento de Neurobiologia, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ, Brazil.
Araújo
Sheila Espírito Santo
SE
Gomes
Ana Lucia Tavares
AL
Sholl-Franco
Alfred
A
da Cunha Faria Melibeu
Adriana
A
Serfaty
Claudio Alberto
CA
Campello-Costa
Paula
P
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
D019922:GAP-43 Protein