Abstract
Purpose: :
Neurturin (NRTN) belongs to the glial cell line derived neurotrophic factor (GDNF) family. It has been shown that NRTN deficiency in mice leads to decreased retinal activity measured via electroretinography. Retinas from NRTN-/- mice also demonstrate reduced immunostaining for horizontal cell (HC) dendrites in the outer plexiform layer. The purpose of this study was to characterize HC morphology in NRTN-/- mice and compare it to the wild type (WT).
Methods: :
Whole mount retinas from perfusion-fixed mice were stained with crystals of DiI (1,1'-dioctadecyl-3,3,3,3’-tetramethylindocarbocyanine perchlorate) in 4% Para formaldehyde for 4 days to allow optimal DiI diffusion. A Zeiss LSM 510 confocal microscope was used to identify individual HCs based on their anatomical location and capture images through their full three-dimensional extent. Zeiss LSM Image Browser software was used to determine HC dendritic field areas and to count HC primary dendrites and branch points. Means for NRTN-/- and WT mice were compared with two-tailed student T tests.
Results: :
A total of 21 HCs from NRTN-/- retinas and 18 HCs from WT retinas were analyzed. The mean HC dendritic field area was 5299 µm2 for WT retinas and 5336 µm2 for NRTN-/- retinas (p=0.86), and the mean number of HC primary dendrites was 5.95 for NRTN-/- retinas and 5.94 for WT retinas (p = 0.97). The mean number of HC dendritic branch points in NRTN-/- mice (17.95) was significantly less than that of WT mice (28.24; p<0.001).
Conclusions: :
Horizontal cells from NRTN-/- mice have similar dendritic field areas and numbers of primary branches but significantly reduced numbers of branch points compared to HCs from WT mice. This suggests that NRTN is important in the development of the horizontal cell dendritic arbor.
Keywords: horizontal cells • retina: distal (photoreceptors, horizontal cells, bipolar cells) • anatomy