LOCALIZATION AND AGE-DEPENDENT EXPRESSION OF HEXOKINASE MESSENGER-RNAIN THE RAT-BRAIN

Localization of mRNA encoding for the enzyme hexokinase and its regula tion in aged animals was carried out in rat brain using the in situ hy bridization technique. The highest levels of the hybridization signal were observed in the olfactory bulb, piriform cortex, tenia tecta, hip pocampus and granular cells of the cerebellum. Other brain areas and n uclei including cerebral cortex, thalamus, hypothalamus, substantia ni gra, subiculum, choroid plexus and superior colliculus displayed moder ate to low density of transcripts. Correlation between relative hexoki nase content and levels of its mRNA was found only for some brain regi ons such as caudate-putamen, geniculate nucleus, ventral and lateral t halamic nuclei, superior colliculus and granular cells of the cerebell um. In the cerebral cortex and hippocampus of old animals the expressi on of hexokinase was significantly increased at 18 and 24 months of ag e. From the present data we conclude that although hexokinase is an ub iquitous enzyme, sites of synthesis display a discrete and uneven loca lization in rat CNS and expression, in the aging brain, might be regul ated to compensate for reduced oxidative phosphorylation in the brain tissue.