Tian, X., Scott, S. A., Weingartner, J.A., and Crutcher, Enhanced sympathetic neurite outgrowth on rat hippocampal tissue sections following septal lesions, Brain Research, 725:111-114 (1996).
Abstract
Increases in hippocampal nerve growth factor (NGF)-like activity are known to occur following removal of cholinergic input. The current study was designed to determine whether this change is accompanied by an increase in the ablility of hippocampal tissue sections to stimulate sympathetic fiber outgrowth when used as culture substrates. Ten Fisher 344 rats underwent a surgical procedure for electrolytic lesion of the medial septal nucleus. In half of these animals, the electrode was lowered into the septum and current was delivered (the remaining 5 animals served as sham controls). One to 3 weeks later, all animals were sacrificed. Sympathetic explants from E9 chick embryos were then cultured on sections of the hippocampus for 3 days, without addition of exogenous NGF. Neurite halos were visualized with a fluorescent vital dye and quantified using an established approach incorporating both areal and fiber density measurements. Tissue sections from lesioned animals elicited significantly greater neurite outgrowth (by ~80%) versus those obtained from sham control animals. A significant portion of this outgrowth could be blocked by antibodies directed against NGF, based on separate experiments in which explants and the sections were incubated either with polyclonal NGF antisera or with preimmune serum. These results demonstrate that cholinergic denervation alters the neurite growth-promoting properties of hippocampal tissue sections when used as substrates in vitro and further suggest that, under these conditions, sympathetic neurite outgrowth depends on factors in addition to NGF.
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