Visualization of spinal afferent innervation in the mouse colon by AAV8-mediated GFP expression
Article first published online: 18 DEC 2012
© 2012 Blackwell Publishing Ltd
Neurogastroenterology & Motility
Volume 25, Issue 2, pages e89–e100, February 2013
How to Cite
Schuster, D. J., Dykstra, J. A., Riedl, M. S., Kitto, K. F., Honda, C. N., McIvor, R. S., Fairbanks, C. A. and Vulchanova, L. (2013), Visualization of spinal afferent innervation in the mouse colon by AAV8-mediated GFP expression. Neurogastroenterology & Motility, 25: e89–e100. doi: 10.1111/nmo.12057
- Issue published online: 22 JAN 2013
- Article first published online: 18 DEC 2012
- Received: 24 August 2012 Accepted for publication: 7 November 2012
Background Primary afferent neurons whose cell bodies reside in thoracolumbar and lumbosacral dorsal root ganglia (DRG) innervate colon and transmit sensory signals from colon to spinal cord under normal conditions and conditions of visceral hypersensitivity. Histologically, these extrinsic afferents cannot be differentiated from intrinsic fibers of enteric neurons because all known markers label neurons of both populations. Adeno-associated virus (AAV) vectors are capable of transducing DRG neurons after intrathecal administration. We hypothesized that AAV-driven overexpression of green fluorescent protein (GFP) in DRG would enable visualization of extrinsic spinal afferents in colon separately from enteric neurons.
Methods Recombinant AAV serotype 8 (rAAV8) vector carrying the GFP gene was delivered via direct lumbar puncture. Green fluorescent protein labeling in DRG and colon was examined using immunohistochemistry.
Key Results Analysis of colon from rAAV8-GFP-treated mice demonstrated GFP-immunoreactivity (GFP-ir) within mesenteric nerves, smooth muscle layers, myenteric plexus, submucosa, and mucosa, but not in cell bodies of enteric neurons. Notably, GFP-ir colocalized with CGRP and TRPV1 in mucosa, myenteric plexus, and globular-like clusters surrounding nuclei within myenteric ganglia. In addition, GFP-positive fibers were observed in close association with blood vessels of mucosa and submucosa. Analysis of GFP-ir in thoracolumbar and lumbosacral DRG revealed that levels of expression in colon and L6 DRG appeared to be related.
Conclusions & Inferences These results demonstrate the feasibility of gene transfer to mouse colonic spinal sensory neurons using intrathecal delivery of AAV vectors and the utility of this approach for histological analysis of spinal afferent nerve fibers within colon.