Rat tooth pulp cells elicit neurite growth from trigeminal neurones and express mRNAs for neurotrophic factors in vitro

Molecular factors control the developmental ingrowth of axons to the tooth pu Ip. Here we examine the ability of pulpal cells to induce neurite outgro wth from neonatal rat trigeminal neurones (TGNs) in vitro. We found that TG Ns emitted neurites and formed networks of branches in relation to pulpal c ells. Neurones co-cultured with a mixture of pulpal cells and 3T3 fibroblas ts formed networks exclusively in relation to the pulpal cells. Cultivated pulpal cells and pulpal tissue produced mRNAs for all neurotrophins and mem bers of the glial cell line-derived neurotrophic factor family. Hence, rat pulpal cells have neuritogenic effects on single TGNs in vitro, that may be associated with secretion of neurotrophic factors. (C) 2001 Elsevier Scien ce Ireland Ltd. All rights reserved.