Anatomical and cytochemical relationships of adenosine deaminase-containing primary afferent neurons in the rat.
The distribution of adenosine deaminase-containing neurons and fibers in the spinal cord and medulla was examined and the relationship of dorsal root ganglia neurons containing this enzyme to those containing somatostatin, substance P, fluoride-resistant acid phosphatase (FRAP) and 5'-nucleotidase was determined using immunohistochemical and histochemical methods. In the spinal cord adenosine deaminase-immunoreactive fibers and neurons were confined to layer I and IIo. A similar localization of these was observed in the spinal trigeminal nucleus. In adult animals treated neonatally with capsaicin adenosine deaminase-positive fibers were totally depleted in layer IIo but only partially depleted in layer I. Analysis of lumbar sensory ganglia revealed that small type-B neurons immunoreactive for adenosine deaminase were also immunoreactive for somatostatin but not substance P. In addition, adenosine deaminase-positive neurons lacked histochemical reaction-product for FRAP and exhibited the lowest activity of 5'-nucleotidase. Examination of the neuronal populations containing the two phosphatase enzymes showed that a proportion of neurons exhibiting 5'-nucleotidase activity were devoid of FRAP activity. It is concluded that dorsal root ganglia neurons immunoreactive for adenosine deaminase and somatostatin constitute a single subpopulation of type-B ganglion cells separate from those containing substance P or FRAP. It appears that the lack of coexistence of adenosine deaminase with either FRAP or 5'-nucleotidase cannot be attributed simply to a coexistence of the two latter enzymes since some 5'-nucleotidase-positive neurons lacking FRAP were also devoid of adenosine deaminase-immunoreactivity. Insofar as these three enzymes may contribute to the regulation of transmission processes in primary sensory neurons, our results indicate a minimal functional relationship between adenine nucleoside and nucleotide degrading enzymes in these neurons. In addition, FRAP appears to have some functional independence from 5'-nucleotidase.
Nagy
J I
JI
Daddona
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PE
D015720:5'-Nucleotidase; D000135:Acid Phosphatase / Q000378:metabolism; D000243:Adenosine Deaminase / Q000378:metabolism*; D000818:Animals; D005455:Fluorescent Antibody Technique; D005727:Ganglia, Spinal / Q000201:enzymology*; D007124:Immunoenzyme Techniques; D008297:Male; D009475:Neurons, Afferent / Q000201:enzymology; D009700:Nucleoside Deaminases / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism; D013116:Spinal Cord / Q000201:enzymology*; D013373:Substance P / Q000378:metabolism; D014279:Trigeminal Nucleus, Spinal / Q000378:metabolism
D013373:Substance P; D013004:Somatostatin; D009708:Nucleotidases; D000135:Acid Phosphatase; D015720:5'-Nucleotidase; D009700:Nucleoside Deaminases; D000243:Adenosine Deaminase