BRAIN-TISSUE HYDROLYSATE ACTS ON PRESYNAPTIC ADENOSINE RECEPTORS IN THE RAT HIPPOCAMPUS

Adenosine is a potent inhibitory modulator in the brain. It suppresses glutamatergic synaptic transmission and possibly acts as a brain endo genous neuroprotective agent. In this study we have examined the effec ts of a clinically used porcine brain tissue hydrolysate, Cerebrolysin (TM), on synaptic transmission in the CA1 area of rat hippocampal slic es. A major effect of the drug at doses approximating those administer ed clinically to demented patients was a depression of synaptic transm ission at the Schaffer collateral-commissural pathway in CA1. Detailed analysis showed that the inhibition is presynaptic and can be reduced by low doses of a specific blocker of adenosine A, receptors, 8-cyclo pentyltheophylline. Because Cerebrolysin(TM) does not contain a detect able amount of adenosine, the effect on adenosine A, receptors must be indirect, perhaps by release of the endogenous agonist. This action o f Cerebrolysin(TM) is consistent with a putative neuroprotective actio n underlying its clinical usage.