1. Nucleosides potentially participate in the neuronal functions of the brain. However,
their distribution and changes in their concentrations in the human brain is not known.
For better understanding of nucleoside functions, changes of nucleoside concentrations
by age and a complete map of nucleoside levels in the human brain are actual requirements.2.
We used post mortem human brain samples in the experiments and applied a recently
modified HPLC method for the measurement of nucleosides. To estimate concentrations
and patterns of nucleosides in alive human brain we used a recently developed reverse
extrapolation method and multivariate statistical analyses.3. We analyzed four nucleosides
and three nucleobases in human cerebellar, cerebral cortices and in white matter in
young and old adults. Average concentrations of the 308 samples investigated (mean+/-SEM)
were the following (pmol/mg wet tissue weight): adenosine 10.3+/-0.6, inosine 69.5+/-1.7,
guanosine 13.5+/-0.4, uridine 52.4+/-1.2, uracil 8.4+/-0.3, hypoxanthine 108.6+/-2.0
and xanthine 54.8+/-1.3. We also demonstrated that concentrations of inosine and adenosine
in the cerebral cortex and guanosine in the cerebral white matter are age-dependent.4.
Using multivariate statistical analyses and degradation coefficients, we present an
uneven regional distribution of nucleosides in the human brain. The methods presented
here allow to creation of a nucleoside map of the human brain by measuring the concentration
of nucleosides in microdissected tissue samples. Our data support a functional role
for nucleosides in the brain.