Neurotensin transcription is oppositely regulated during development and regeneration

Our previous work demonstrated that neurotensin mRNA expression was transiently up-regulated during development in the hypoglossal motoneurone. The present study was carried out to examine how neurotensin mRNA expression changes during nerve regeneration. Following either unilateral resection or crushing of the hypoglossal nerve, mRNA expression was detected by non-radioactive in situ hybridization histochemistry using an alkaline phosphatase-labelled oligonucleotide probe. A reduction in neurotensin mRNA was observed on the operated side after the nerve injury. It took around 2 months for NT mRNA levels to return to normal. Similar down-regulation was observed following crushing, but recovery was more rapid than that observed with sectioning, probably due to the extent of nerve damage. This finding indicates that neurotensin transcription is up-regulated during development but, on the contrary, down-regulated during regeneration.