[Horseradish peroxidase retrograde labeling of primary sensory axons in rats: a comparison between three different intraspinal injections methods].
OBJECTIVE
In order to improve the results of intraspinal retrograde labeling of post-ganglionic primary sensory axons by horseradish peroxidase (HRP), the authors compared three different intraspinal injection methods of this tracer into the inferior thoracic spinal cord in the rat.


METHODS
'Open field' method (group 1, N = 8); stereotactic injection, needle tip diameter = 0.72 mm (group 2, N = 8); stereotactic injection, needle tip diameter = 0.24 mm (group 3, N = 8). Histological features of the spinal injection site showed that tissue damages due to injection was more extensive and deeper than expected. HRP transported in retrograde fashion from injection site to sensory body cells located in dorsal root ganglia (DRG) was revealed by the Mesulam histochemical technique.


RESULTS
The mean number of labeled neurons per DRG was 652 in group 3, 116 in group 2, and 77 in group 1. Differences were statistically significant, especially between groups 1 and 3 (P = 4.10(-16)) and groups 2 and 3 (P = 2.10(-17)).


CONCLUSIONS
Retrograde labeling of primary sensory axons by HRP (or another axonal tracer) with fine needle stereotactic intraspinal injection may represent an alternative to anterograde labeling. This reliable and reproducible method may be useful in studies dealing with regeneration of post-ganglionic primary sensory axons.
Dam Hieu
P
P
Laboratoire de neurochirurgie expérimentale, centre hospitalier universitaire de Bicêtre, Le Kremlin-Bicêtre, France.
Liu
S
S
Bonnard
A S
AS
Boisset
N
N
Genty
E
E
Tadié
M
M
D000818:Animals; D001338:Autonomic Fibers, Postganglionic / Q000648:ultrastructure*; D001369:Axons / Q000648:ultrastructure*; D006651:Histocytochemistry / Q000379:methods*; D006735:Horseradish Peroxidase / Q000008:administration & dosage*; D007278:Injections, Spinal / Q000295:instrumentation / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling / Q000379:methods*; D013238:Stereotaxic Techniques / Q000295:instrumentation
D006735:Horseradish Peroxidase