Excitatory effect of adenosine on neurotransmission in the slices of superior colliculus and hippocampus of guinea pig.

Postsynaptic potential (PSP) was recorded from the CA3 region of the pyramidal cell layer of hippocampal slices and from the superficial gray layer of superior collicular slices from guinea pigs. In the hippocampal slices, application of adenosine to the perfusion medium at a concentration of 10 nM to 1 microM enhanced the amplitude of the PSP and at concentrations greater than 10 microM it depressed the PSP. The dose-response curve of the effect of adenosine on neurotransmission in the hippocampus thus showed an excitatory and inhibitory biphasic pattern according to the concentrations applied. However, in superior collicular slices, application of adenosine at concentrations of more than 10 nM enhanced the amplitude of the PSP and there was no inhibition by adenosine even at a concentration of 1 mM.