Journal of Neuroscience, Vol 9, 2654-2663, Copyright © 1989 by Society for Neuroscience
Extracellular cAMP accumulation and degradation in rat cerebral cortex in dissociated cell culture
PA Rosenberg and MA Dichter
Department of Neurology, Children's Hospital, Boston, Massachusetts 02115.
Norepinephrine (NE) stimulated the accumulation of cAMP in embryonic rat
cerebral cortex in dissociated cell culture. After exposure to NE for 10
min, the intracellular cAMP content of these cultures went from 22 +/- 12
to 202 +/- 75 pmol/mg protein. Using selective culturing techniques,
evidence was obtained supporting the hypothesis that NE- stimulated
production of cAMP is a property associated with the glial rather than the
neuronal component of these cultures. Beta adrenergic agonist stimulation
of cortical cultures also resulted in the efflux of cAMP into the medium.
At the peak of extracellular accumulation of cAMP (following a 40-min
exposure to isoproterenol), 180 pmol cAMP/mg protein had been transported
into the extracellular medium. The fate of extracellular cAMP was
investigated using thin-layer chromatography. Extracellular cAMP was
degraded to AMP and adenosine; this degradation did not seem to be due to
the presence of serum or serum components, suggesting the existence of an
extracellular phosphodiesterase. In response to NE stimulation of glia, in
particular astrocytes, cAMP or its metabolites may accumulate at high
enough concentrations in the extracellular space in cerebral cortex to
affect neuronal function, possibly via adenosine receptors.