Developmental shift of synaptic vesicle protein 2 from axons to terminals in the primary visual projection of the hamster

• Published in: Neuroscience Vol. 77; no. 4; pp. 1225 - 1236
• Main Authors: Confaloni, A, Lyckman, A.W, Moya, K.L
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.1997; Elsevier
• Subjects: Animals; Antibodies, Monoclonal; axon elongation; Biological and medical sciences; Cells, Cultured; Cricetinae; development; Development. Senescence. Regeneration. Transplantation; Eye Enucleation; Fundamental and applied biological sciences. Psychology; Geniculate Bodies - cytology; Geniculate Bodies - growth & development; Immunohistochemistry; Membrane Glycoproteins - analysis; Membrane Glycoproteins - immunology; Membrane Glycoproteins - metabolism; Mesocricetus; Nerve Tissue Proteins - analysis; Nerve Tissue Proteins - immunology; Nerve Tissue Proteins - metabolism; Neurotransmitter Agents - analysis; Neurotransmitter Agents - immunology; Neurotransmitter Agents - metabolism; Presynaptic Terminals - chemistry; Presynaptic Terminals - metabolism; Retina - chemistry; Retina - cytology; Retina - growth & development; retinal axon; Superior Colliculi - cytology; Superior Colliculi - growth & development; synaptic vesicle protein 2; synaptogenesis; Vertebrates: nervous system and sense organs; Visual Pathways; GAP, growth-associated protein; SGS, stratum griseum superficiale; NHS, normal horse serum; EGTA, ethyleneglycolbis(aminoethylether)tetra-acetate; retinal axon; OT, optic tract; P, postnatal day; LGN, lateral geniculate nucleus; PBS, phosphate-buffered saline; PVDF, polyvinylidene difluoride; TH, total homogenate; SO, stratum opticum; SDS, sodium dodecyl sulphate; CY, cytosolic fraction; synaptic vesicle protein 2; development; BSA, bovine serum albumin; SC, superior colliculus; SV2, synaptic vesicle protein 2; PBSTN, PBS containing Triton X-100 and NaN 3; axon elongation; MAb, monoclonal antibody; TP, total particulate; TBST, Tris buffered saline with Tween-20; synaptogenesis; Synaptogenesis; Rodentia; Synaptic vesicle; Axon; Projection; Retina; Postnatal development; Colliculus superior; Proteins; Vertebrata; Mammalia; Lateral geniculate body; Visual pathway; Hamster
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(96)00548-9

Synaptic vesicle protein 2 is an integral synaptic vesicle membrane glycoprotein which is present in all synapses for which it has been examined. We used an anti-synaptic vesicle protein 2 monoclonal antibody to examine synaptic vesicle protein 2 localization in the developing hamster retinofugal pathway. From postnatal day 0 to day 1, a period of elongation of retinal ganglion cell axons to their central targets, fiber fascicles in the optic tract over the lateral geniculate nucleus were intensely synaptic vesicle protein 2-immunoreactive. Adjacent to the optic tract, single fibers could be seen. We also observed a marked immunostaining in growth cones and fiber fascicles in retinal explants in culture. By postnatal day 2, the staining of single fibers had ended, and by postnatal day 5, during the formation of terminal arbors, numerous fine puncta of synaptic vesicle protein 2 immunoreactivity were distributed within the neuropil of the lateral geniculate nucleus. In the adult, the optic tract was devoid of synaptic vesicle protein 2 staining, while the neuropil contained distinct immunoreactive profiles, particularly in the outer shell of the lateral geniculate. These synaptic vesicle protein 2-positive profiles closely resembled the grape-like clusters and large swellings of two known retinal axon terminal types. Eye removal resulted in the rapid disappearance of these synaptic vesicle protein 2-labelled terminal profiles contralateral to the enucleation. A similar pattern of synaptic vesicle protein 2 immunoreactivity was observed in the superior colliculus. From postnatal day 0 to day 2, retinal fiber fascicles in the stratum griseum superficiale/stratum opticum were darkly stained for synaptic vesicle protein 2. By postnatal day 5, the immunoreactivity shifted to the neuropil and from postnatal day 6 onwards, the synaptic vesicle protein 2 immunoreactivity was more intense in the stratum griseum superficiale than in the optic fiber layer. This study demonstrates dense synaptic vesicle protein 2-labelling of elongating axons both in vivo and in vitro. However, coincident with the transition from retinal ganglion cell axon elongation to terminal arborization, synaptic vesicle protein 2 is progressively restricted to synaptic terminals and becomes undetectable in axons. This study is the first to document an axonal localization of synaptic vesicle protein 2 during development and raises the question as to its role during axonal elongation.