ISSN:
1471-4159
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Coupling of CNS receptors to phosphoinositide turnover has previously been found to vary with both age and brain region. To determine whether the metabolism of the second messenger inositol 1,4,5-trisphosphate also displays such variations, activities of inositol 1,4,5-trisphosphate 5′-phosphatase and 3′-kinase were measured in developing rat cerebral cortex and adult rat brain regions. The 5′-phosphatase activity was relatively high at birth (∼50% of adult values) and increased to adult levels by 2 weeks postnatal. In contrast, the 3′-kinase activity was low at birth and reached ∼50% of adult levels by 2 weeks postnatal. In the adult rat, activities of the 3′-kinase were comparable in the cerebral cortex, hippocampus, and cerebellum, whereas much lower activities were found in hypothalamus and pons/medulla. The 5′-phosphatase activities were similar in cerebral cortex, hippocampus, hypothalamus, and pons/medulla, whereas 5-to 10-fold higher activity was present in the cerebellum. The cerebellum is estimated to contain 50–60% of the total inositol 1,4,5-trisphosphate 5′-phosphatase activity present in whole adult rat brain. The localization of the enriched 5′-phosphatase activity within the cerebellum was examined. Application of a histochemical lead-trapping technique for phosphatase indicated a concentration of inositol 1,4,5-trisphosphate 5′-phosphatase activity in the cerebellar molecular layer. Further support for this conclusion was obtained from studies of Purkinje cell-deficient mutant mice, in which a marked decrement of cerebellar 5′-phosphatase was observed. These results suggest that the metabolic fate of inositol 1,4,5-trisphosphate depends on both brain region and stage of development.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1471-4159.1990.tb01976.x
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