G. Ceballos et al., DIFFERENTIAL DISTRIBUTION OF PURINE METABOLIZING ENZYMES BETWEEN GLIAAND NEURONS, Journal of neurochemistry, 62(3), 1994, pp. 1144-1153
Previous studies showed that in cultured chick ciliary ganglion neuron
s and CNS glia, adenosine can be synthesized by hydrolysis of 5'-AMP a
nd that the accumulation of the adenosine degradative products inosine
and hypoxanthine was significantly greater in glial than in neuronal
cultures. Furthermore, previous immunochemical and histochemical studi
es in brain showed that adenosine deaminase and nucleoside phosphoryla
se are localized in endothelial and glial cells but are absent in neur
ons; however, adenosine deaminase may be found in a few neurons in dis
crete brain regions. These results suggested that adenosine degradativ
e pathways may be more active in glia. Thus, we have determined if the
re is a differential distribution of adenosine deaminase, nucleoside p
hosphorylase, and xanthine oxidase enzyme fluxes in glia, comparing pr
imary cultures of central and ciliary ganglion neurons and glial cells
from chick embryos. Hypoxanthine-guanine phosphoribosyltransferase an
d production of adenosine by S-adenosylhomocysteine hydrolase activity
were also examined. Our results show that there is a distinct profile
of purine metabolizing enzymes for glia and neurons in culture. Both
cell types have an S-adenosylhomocysteine hydrolase, but it was more a
ctive in neurons than in glia. In contrast, in glia the enzymatic acti
vities of xanthine oxidase (443 +/- 61 pmol/min/10(7) cells), nucleosi
de phosphorylase (187 +/- 8 pmol/min/10(7) cells), and adenosine deami
nase (233 +/- 32 pmol/min/10(7) cells) were more active at least 100,
20, and five times, respectively, than in ciliary ganglion neurons and
100, 100, and nine times, respectively, than in central neurons.