Leukemia inhibitory factor expression is not induced in activated microglia and reactive astrocytes in response to...

In adult intact rat brain, leukemia inhibitory factor (LIF) mRNA has been found to be constitutively expressed in basal forebrain cholinergic neurons. To reveal a functional role of LIF in neurodegenerative events, the cellular expression pattern of LIF was determined by combining in situ hybridization and immunocytochemistry after specific and selective degeneration of basal forebrain cholinergic cells by a single intracerebroventricular application of the cholinergic immunotoxin 192IgG-saporin. Although basal forebrain cholinergic lesion resulted in a dramatic activation of micro- and astroglial cells at the lesion site, LIF mRNA expression was not detected in any of the lesion-induced activated glial cell types. As the cholinergic immunotoxin exerts its degenerative action by the ribosome-inactivating property of saporin, the lack of glial LIF induction might be due to the incapability of the dying cholinergic cell to form and release factors which induce LIF expression in activated glial cells.