Localization of cholinergic differentiation factor/leukemia inhibitory factor mRNA in the rat brain and peripheral tissues.

Sympathetic neurons display considerable plasticity in the neurotransmitter and neuropeptide phenotypes they express in vitro and in vivo. The cholinergic differentiation factor (CDF, also known as leukemia inhibitory factor, LIF) induces cultured rat sympathetic neurons to become cholinergic, without affecting their survival or growth. To understand the role of this factor in normal development, it is essential to determine where it is produced in situ. To localize CDF/LIF mRNA, a semiquantitative, reverse transcription-polymerase chain reaction method was employed. Actin and tubulin mRNA were used as internal controls, and two different sets of CDF/LIF primers were compared. In postnatal rat peripheral tissues, CDF/LIF mRNA was selectively localized in the target area of developing, sympathetic cholinergic neurons; the mRNA was not detected in the targets of sympathetic noradrenergic neurons. This finding supports the hypothesis that CDF/LIF is a target-derived neuronal differentiation factor. In postnatal rat brain, CDF/LIF mRNA is localized selectively in two parts of the visual system, visual cortex and superior colliculus. Thus, CDF/LIF may play a role in this system as well.