title: Developmental changes in the expression level of connexin36 in the rat retina.
abstract: Connexin36 (Cx36) is the major gap junction forming protein in the brain and the retina; thus, alterations in its expression indicate changes in the corresponding circuitry. Many structural changes occur in the early postnatal retina before functional neuronal circuits are finalized, including those that incorporate gap junctions. To reveal the time-lapse formation of inner retinal gap junctions, we examine the developing postnatal rat retina from birth (P0) to young adult age (P20) and follow the expression of Cx36 in the mRNA and protein levels. We found a continuous elevation in the expression of both the Cx36 transcript and protein between P0 and P20 and a somewhat delayed Cx36 plaque formation throughout the inner plexiform layer (IPL) starting at P10. By using tristratificated calretinin positive (CaR(+)) fibers in the IPL as a guide, we detected a clear preference of Cx36 plaques for the ON sublamina from the earliest time of detection. This distributional preference became more pronounced at P15 and P20 due to the emergence and widespread expression of large (>0.1 μm(2)) Cx36 plaques in the ON sublamina. Finally, we showed that parvalbumin-positive (PV(+)) AII amacrine cell dendrites colocalize with Cx36 plaques as early as P10 in strata 3 and 4, whereas colocalizations in stratum 5 became characteristic only around P20. We conclude that Cx36 expression in the rat IPL displays a characteristic succession of changes during retinogenesis reflecting the formation of the underlying electrical synaptic circuitry. In particular, AII cell gap junctions, first formed with ON cone bipolar cells and later with other AII amacrine cells, accounted for the observed Cx36 expressional changes.
authors.affiliation: Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Ifjúság street 6, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Kovács-Öller
authors.forename: Katalin
authors.initials: K
authors.lastname: Raics
authors.forename: József
authors.initials: J
authors.lastname: Orbán
authors.forename: Miklós
authors.initials: M
authors.lastname: Nyitrai
authors.forename: Béla
authors.initials: B
authors.lastname: Völgyi
mesh_terms: D025042:Amacrine Cells / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017630:Connexins / Q000235:genetics* / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017208:Rats, Wistar; D012160:Retina / Q000254:growth & development* / Q000378:metabolism*; D000097004:Gap Junction delta-2 Protein
chemical_list: D017630:Connexins; D012333:RNA, Messenger; D000097004:Gap Junction delta-2 Protein