Abstract
Purpose :
Several catecholamine-related Cre driver mouse lines fail to drive fluorescent reporter expression in types 1 and 2 catecholaminergic amacrine cells. We retested the DAT-Cre driver mouse line reported to label four distinct amacrine cell types and found in them a single wide-field ON-OFF amacrine cell type with dendrites stratifying at the middle of the inner plexiform layer.
Methods :
The DAT-Cre line (Stock No. 006660) was obtained from Jax in 2010 and 2015 and mated into the Ai-9 background (Stock No. 007905). Primers designed to be specific for this line were developed for genotyping to prevent inadvertent mix up with other Cre lines. The level of dendritic stratification was determined in reference to IPL depth markers such as TH, VAChT and CART. Light responses were recorded under dim red light by whole-cell current clamp recordings. Morphology of recorded neurons was recovered by staining for internally dialyzed biocytin, followed by confocal imaging and tracing in Neurolucida 360 and morphometric analysis.
Results :
The cell bodies of labeled neurons are negative for TH and reside mostly in the INL and occasionally in GCL. Our DAT-Cre specific primers do not pick up other Cre drivers. Dendritic stratification of labeled neurons is found at the center of IPL and identical in mice obtained in 2010 and 2015. These cells do not spike and transiently depolarize at both light onset and offset. L-AP4 blockade or genetic removal of the ON-pathway in the Nob background eliminates only the ON light responses.
Conclusions :
The DAT-Cre mouse allows the labeling of a unique wide-field ON-OFF amacrine cell type and is more specific than previously reported.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.