Differential distribution of rat PDE-7 mRNA in embryonic and adult rat brain.

Currently not much is known about the distribution and function of the phosphodiesterase type 7 (PDE-7) enzyme. Therefore, we carried out an extensive distribution analysis of the rat and human PDE-7 by in situ hybridization as well as RT-PCR. We isolated a partial rat cDNA clone that is highly homologous to the sequence of the human PDE-7 gene. RT-PCR tissue distribution analyses revealed expression of the mRNA of the human and rat-enzymes in most of the examined tissues, like adult heart, lung, brain, and liver, as well as in several cell lines of the immune system. In situ hybridization with the rat PDE-7 showed a differential expression pattern during the late phases of the developing rat brain with higher levels of mRNA in cortical and telencephalic structures in d 16, 18, and 20 embryonic stages, whereas in adult rat brain, higher amounts of mRNA could only be detected in cerebellum and, to a lesser extent, in hippocampus and the olfactory system.