Influence of non-neuronal cells on establishment of neuropeptide Y expression by sympathetic neurons in vitro.

Sympathetic ganglion precursors were used to test the role of non-neuronal cell-derived factors in the establishment of mature neuronal phenotypes. In control conditions, characteristic neuronal populations with and without neuropeptide Y (NPY) expression developed after 1 week, but following removal of non-neuronal cells, virtually all neurons expressed NPY. Thus, ganglionic non-neuronal cells downregulated NPY expression in some but not all neurons in vitro. Conditioned medium from non-neuronal cells restored heterogeneous NPY expression, a finding that suggests the factors are soluble. A non-neuronal cell-derived cytokine, leukemia inhibitory factor, dramatically reduced NPY expression in all neurons, but no concentration tested could recapitulate heterogeneous neuronal NPY expression. Sympathetic precursors that incorporated BrdU early in the culture were more likely to develop NPY expression than neurons that became postmitotic later in vitro. Together, these findings support the notion that the environment in which neurons become postmitotic contributes to neuronal phenotype. Copyright 2001 S. Karger AG, Basel