Kazuho Abe and Hiroshi Saito
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences,
The University of Tokyo, Tokyo 113, Japan
Abstract: When cultured astrocytes are treated with agents that
elevate intracellular cyclic AMP, they become process-bearing stellate cells.
In the present study, we investigated possible developmental changes of
astrocyte stellation induced by beta-adrenoceptor stimulaton. Cultured astrocytes
were prepared from the cerebral cortices of embryonic day 18 (E18) and postnatal
day 2 (P2) rats. Treatment with the beta-adrenoceptor agonist isoproterenol
induced stellation in P2 astrocytes more potently and rapidly than in E18
astrocytes. Isoproterenol-stimulated increase in cellular cyclic AMP levels
was very similar in E18 and P2 astrocytes. The membrane-permeable cyclic
AMP analog dibutyryl cyclic AMP induced stellation in P2 astrocytes more
potently and rapidly than in E18 astrocytes. Stellation induced by the protein
kinase C activator phorbol ester was not different between E18 and P2 astrocytes.
These results suggest that beta-adrenoceptor-mediated astrocyte stellation
increases during development and that this change is attributed to the development
of mechanisms downstream from cyclic AMP production.
Keywords: beta-Adrenoceptor, Cyclic AMP, Protein kinase C, Astrocyte,
Stellation