Regulation of galanin in rat sympathetic neurons in vitro.

The neuropeptide galanin is induced in sensory and autonomic neurons after peripheral nerve lesion. Leukemia inhibitory factor (LIF) has been suggested to be involved in the up-regulation of galanin. A direct effect of LIF on galanin content in pure sympathetic neuron cultures dissociated from newborn rat superior cervical ganglia was investigated by radioimmunoassay and immunohistochemistry. Galanin increases in sympathetic neurons during a 12 day culture period in the presence of NGF (10 ng/ml). Five days after addition of LIF (10 ng/ml) a 7-fold elevation is observed when compared to control cultures. Furthermore, galanin increases significantly in the presence of non-neuronal cells and in response to potassium-induced depolarization. The proportion of galanin-immunoreactive neurons in mixed cultures is similar to that found in adult rat superior cervical ganglia after transection of the major postganglionic branches. The results corroborate the hypothesis that LIF, presumably released from ganglionic satellite cells, induces galanin in a subpopulation of sympathetic neurons in vivo and in vitro.