Changes in mRNA for choline transporter-like protein following facial nerve transection.

When the axon of a motoneuron is transected, axonal regrowth occurs to reconnect it to the correct target. During the regeneration period, a large amount of new membrane synthesis is required for the axons to extend. Choline is an important metabolite in all cells because of the major contribution of phosphatidylcholine and sphingomyelin to the production of membranes. Therefore, choline uptake is necessary for axonal elongation. We cloned rat choline transporter-like protein 1 (rCTL1) as an upregulated gene in the axotomized facial motor nucleus by differential display polymerase chain reaction using adult rat facial nerve axotomy model. rCTL1 belongs to the choline transporter-like protein family, which takes up choline. We investigated the changes in rCTL1 mRNA levels in the facial motor nucleus of adult rats following axotomy by in situ hybridization. In the facial motoneurons signals of rCTL1 mRNA were rarely expressed, were transiently increased following axotomy and gradually returned to the control level. These results suggest that rCTL1 is involved in activated choline uptake for membrane synthesis in motoneurons following nerve transection.