Induction of raf-1 protein immunoreactivity in guinea pig hippocampal slices during the in vitro maintenance.

The cellular raf-1 protooncogene encodes a cytoplasmic serine/threonine protein kinase; raf-1 is expressed not only in tumour cells, but also in normal brain tissue. However, the substrate of raf-1 kinase is unknown and its function is still hypothetical. In cell cultures, mitogen stimulation may alter its properties, including its kinase activity and subcellular distribution. The aims of the present study were: (1) light- and electron microscopic immunohistochemical localization of raf-1 kinase in hippocampal slices; (2) the follow-up of the possible changes in localization and detectability during the in vitro maintenance and low-frequency stimulation. Our results suggested the induction of neuronal raf-1 kinase during the in vitro maintenance. The possibilities of increased transcription and enzyme activation are discussed.