NEURONAL EXPRESSION OF LEUKEMIA INHIBITORY FACTOR (LIF) IN THE RAT-BRAIN

Very little is known about the action of the leukemia inhibitory facto r (LIF) in the central nervous system. To analyze LIF expression in ad ult rat brain, we used non-radioactive in situ hybridization with digo xigenin-labeled RNA probes, in combination with immunohistochemistry t o identify the cell types expressing LIF mRNA. Hippocampal pyramidal c ells, hilar interneurons and granule cells of the dentate gyrus displa y strong hybridization signals, while neurons of the cerebral cortex, cerebellum, cholinergic basal forebrain nuclei, and the striatum are l abeled as well. The most prominent expression in cerebral cortex is in layers IV and VI. Glial fibrillary acidic protein-positive astrocytes did not display a detectable LIF hybridization signal suggesting that LIF mRNA is predominantly expressed in neurons in the normal, adult r at brain, although a presence in resting microglial cells cannot be ex cluded.