Calcitonin gene-related peptide in primary afferent neurons of rat: co-existence with fluoride-resistant acid phosphatase and depletion by neonatal capsaicin.
Immunohistochemical and histochemical techniques were used to re-examine the extent to which neonatal capsaicin treatment depletes calcitonin gene-related peptide in the dorsal horn of the spinal cord, to determine the localization of calcitonin gene-related peptide in relation to that of fluoride-resistant acid phosphatase in lumbar dorsal root ganglia, and to compare the distribution of these primary afferent markers in the dorsal horn. A substantial depletion of calcitonin gene-related peptide was observed in the dorsal horn of adult rats treated neonatally with capsaicin suggesting that a large proportion of this peptide in the dorsal horn is contained within capsaicin-sensitive primary afferent fibers. In dorsal root ganglia 30% of all or 44% of small- and medium-sized calcitonin gene-related peptide-immunoreactive cells were positive for fluoride-resistant acid phosphatase. Conversely, 50% of cells positive for the phosphatase enzyme also displayed immunoreactivity for the peptide. In lamina II of the dorsal horn calcitonin gene-related peptide and fluoride-resistant acid phosphatase were found to have an overlapping distribution. The presence of fluoride-resistant acid phosphatase in a substantial proportion of neuropeptide-containing primary sensory neurons suggests a lack of segregation of sensory neuronal populations into peptide- and non-peptide-containing subgroups at least on the basis of non-peptide neurons defined as those containing fluoride-resistant acid phosphatase.
Carr
P A
PA
Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Yamamoto
T
T
Nagy
J I
JI
D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002211:Capsaicin / Q000494:pharmacology*; D004351:Drug Resistance; D005459:Fluorides / Q000494:pharmacology*; D007150:Immunohistochemistry; D009475:Neurons, Afferent / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000135:Acid Phosphatase; D015740:Calcitonin Gene-Related Peptide; D005459:Fluorides; D002211:Capsaicin