LOCALISATION OF THE HIGH-AFFINITY CHOLINE
TRANSPORTER-1 IN RAT SKELETAL MUSCLE AND
SPINAL CORD
K.S. Lips, U. Pfeil, R.V. Haberberger, W. Kummer
Institute for Anatomy and Cell Biology, Justus-Liebig-University,
Giessen, Germany
Acetylcholine (Ach) is synthesised by choline acetyltransferase in the
cytoplasm of cholinergic neurons. The vesicular acetylcholine transporter
(VAChT) imports ACh into synaptic vesicles. After exocytotic release it is
split into acetate and choline. Choline is taken up into the synaptic terminal
via a high-affinity choline transporter (CHT) for resynthesis of ACh. The
first high-affinity CHT (CHT1) was recently cloned, and in-situ
hybridization showed its expression in spinal motoneurons. We generated
polyclonal antisera against a synthetic peptide corresponding to aa residues
29-40 of the rat CHT1 sequence. These antisera were used in
immunofluorescence to analyse the distribution of the CHT1 protein either
singly or in combination with antisera against VAChT to label cholinergic
terminals, and Alexa-488 conjugated a-bungarotoxin to label motor end
plates. Perikarya of spinal motoneurons were moderately CHT1- and
VAChT-immunoreactive, while the recurrent cholingeric synapses were
intensely CHT1- and VAChT-immunolabelled. In skeletal muscles, motor
end plates showed an intense CHT1- and VAChT-immunoreactivity, while
preterminal axons showed a distinct CHT1- but only weak VAChT-
immunolabelling. The results show a preferential localisation of the CHT1
protein at the neuro-neuronal and neuro-muscular synapse, well in line with
its anticipated function in the synaptic transmitter recycling. (supported by
the DFG, SFB 547) .
108 Haberberger