Changes of expression levels of choline acetyltransferase and vesicular acetylcholine transporter mRNAs after transection of the hypoglossal nerve in adult rats

Acetylcholine, synthesized in the cytoplasm of cholinergic neurons by choline acetyltransferase (CHAT), is packaged in synaptic vesicles by vesicular acetylcholine transporter (VAChT). The entire VAChT gene has been reported to be located within the first intron of the ChAT gene. In order to examine whether or not ChAT and VAChT transcription may be coordinately regulated, the levels of ChAT and VAChT mRNAs in hypoglossal neurons were analyzed by in situ hybridization following transection of the hypoglossal nerve in adult rats. After unilateral transection, the levels of expression of ChAT and VAChT mRNAs were dramatically reduced in the ipsilateral hypoglossal nucleus I week after the surgery. However the expression of both mRNAs gradually recovered thereafter. These results suggest that the transcription of the two cholinergic genes is tightly linked in motor neurons.