title: Evaluation of the effects of various additives on retrograde labelling by horseradish peroxidase applied to intact and transected hindlimb nerves of rat and rabbit.
abstract: The number of retrogradely labelled motor, sensory and sympathetic neurons were determined after application of concentrated solutions of horseradish peroxidase to transected rat sural and medial gastrocnemius nerves and rabbit sural nerves. In some experiments, the number of labelled cell bodies approached the number of axons counted from electronmicrographs of the nerve trunk. In the other experiments, deficits apparently resulted from failure to label some small neurons, because the mean size of labelled somata was higher. Incorporation of dimethylsulphoxide, poly-L-ornithine or a detergent (Teric-X8) in the applied solution did not significantly increase the number of labelled neurons. When horseradish peroxidase was applied outside nerves that were not transected, only the inclusion of Teric-X8 consistently produced labelling, but of less than 5% of the total axonal population. Other solutions occasionally produced labelling of even fewer cells, probably because of unintentional axon damage. The data suggest that a reasonable quantitative description of the population of axons projecting in a peripheral nerve trunk can be made by retrograde labelling with horseradish peroxidase applied during deliberate disruption of all axons. Small neurons, presumably with fine axons, may not always be labelled, even if chemical additives thought to facilitate penetration or uptake of the tracer are used.
mesh_terms: D000320:Adrenergic Fibers / Q000187:drug effects; D000818:Animals; D001370:Axonal Transport / Q000187:drug effects; D002452:Cell Count; D003902:Detergents; D004121:Dimethyl Sulfoxide; D005260:Female; D006614:Hindlimb / Q000294:innervation*; D006735:Horseradish Peroxidase; D008297:Male; D009046:Motor Neurons / Q000187:drug effects; D009409:Nerve Crush; D009474:Neurons / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D009475:Neurons, Afferent / Q000187:drug effects; D010455:Peptides; D010544:Peroxidases; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity; D013497:Sural Nerve / Q000648:ultrastructure
chemical_list: D003902:Detergents; D010455:Peptides; C008973:polyornithine; D006735:Horseradish Peroxidase; D010544:Peroxidases; D004121:Dimethyl Sulfoxide