Abstract
Cyclic nucleotide phosphodiesterase was demonstrated in rat and hamster hippocampus by a histochemical method. This method is based on a cerium precipitation technique. The enzymatic reaction was specific and demonstrated the distribution of cyclic nucleotide phosphodiesterase in the hippocampal fields of rats and hamsters. There were no differences between cAMP and cGMP as substrates. There were very strong reaction in the pyramidal layer, in the neuropil of the molecular layer and in the mossy fibre layer. Strong enzymatic activity was localized in pyramidal cells in their dendrites, filial cells and capillaries.
