Biphasic effects of polarizing current on adenosine-sensitive generation of cyclic AMP in rat cerebral cortex

Cyclic AMP accumulation elicited by adenosine was investigated in cortical slices of rats following the application of a weak anodal direct current (anodal polarization) to the unilateral sensorimotor cortex. Anodal polarization with 3.0 microA for 30 min caused an increase in the adenosine-elicited accumulation of cyclic AMP in the polarized cortex, in which case the increase in the polarized cortical region was highlighted by repeated applications of the currents. Polarization with 0.3 microA for 30 min decreased the cyclic AMP accumulation, and polarization with 30.0 microA for 30 min had no effect. When applied for 3 h, the polarizing currents at all of the intensities tested decreased the cyclic AMP accumulation. The results indicate that anodal polarization has biphasic effects on adenosine-elicited accumulation of cyclic AMP in the cortex. Alterations in the cyclic AMP generation are suggested to form the neurochemical basis of central and behavioral activity induced by anodal polarization.