Light and electron microscopic analysis of aquaporin 1-like-immunoreactive amacrine cells in the rat retina.
Aquaporin 1 (AQP1; also known as CHIP, a channel-forming integral membrane protein of 28 kDa) is the first protein to be shown to function as a water channel and has been recently shown to be present in the rat retina. We previously showed (Kim et al. [1998] Neurosci Lett 244:52-54) that AQP1-like immunoreactivity is present in a certain population of amacrine cells in the rat retina. This study was conducted to characterize these cells in more detail. With immunocytochemistry using specific antisera against AQP1, whole-mount preparations and 50-microm-thick vibratome sections were examined by light and electron microscopy. These cells were a class of amacrine cells, which had symmetric bistratified dendritic trees ramified in stratum 2 and in the border of strata 3 and 4 of the inner plexiform layer (IPL). Their dendritic field diameters ranged from 90 to 230 microm. Double labeling with antisera against AQP1 and gamma-aminobutyric acid or glycine demonstrated that these AQP1-like-immunoreactive amacrine cells were immunoreactive for glycine. Their most frequent synaptic input was from other amacrine cell processes in both sublaminae a and b of the IPL, followed by a few cone bipolar cells. Their primary targets were other amacrine cells and ganglion cells in both sublaminae a and b of the IPL. In addition, synaptic output onto bipolar cells was rarely observed in sublamina b of the IPL. Thus, the AQP1 antibody labels a class of glycinergic amacrine cells with small to medium-sized dendritic fields in the rat retina.
Kim
In-Beom
IB
Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea.
Lee
Eun-Jin
EJ
Oh
Su-Ja
SJ
Park
Cheol-Beom
CB
Pow
David V
DV
Chun
Myung-Hoon
MH
D025042:Amacrine Cells / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins / Q000378:metabolism*; D015153:Blotting, Western; D005260:Female; D005998:Glycine / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D012160:Retina / Q000378:metabolism* / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
C496022:Aqp1 protein, rat; D020346:Aquaporins; D051398:Aquaporin 1; D005680:gamma-Aminobutyric Acid; D005998:Glycine