Peripheral type choline acetyltransferase in the human intestine and dorsal root ganglion
演題番号 : P1-b15
Jean-Pierre Bellier:1 Shin Kimura:1 Yuko Sakaue:1 Hiroshi Kimura:1
1:Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Japan
The synthesizing enzyme of acetylcholine, the choline acetyltransferase (ChAT) has two isoforms. In rat, immunoreactivity for the preferentially observed isoform in the peripheral nervous system, the peripheral ChAT (pChAT), was observed in enteric nervous system and also in neurons of the dorsal root ganglion (DRG). The purpose of the present study is to examine pChAT immunohistochemical staining of these two structures in the human. Human specimens, large or small intestine and DRG, obtained within 24 hours postmortem at autopsy in Shiga University of Medical Science, were fixed by immersion in 4% paraformaldehyde in 0.1M phosphate buffer for 4 days at 4°C, and then cryoprotected. Free-floating cryostat sections of 24μm in thickness were used for immunohistochemistry using an avidin-biotin-peroxidase complex method. In human intestines and DRG, the pattern of distribution of pChAT immunostaining was similar to the pattern observed previously in rat. Positive staining was exclusively localized in neuronal cell bodies and fibers. In human large intestine, for instance, pChAT-positive somata were observed in the submucosal and intramural ganglionated plexuses. Networks of positive nerve fibers were found within the submucosa, the longitudinal and the circular muscle; varicoses could be observed. Co-localisation of pChAT staining with other cholinergic markers, the high affinity choline transporter and the vesicular acetylcholine transporter, was observed in nerves fibers. In human DRG, all neuronal somata appeared immunoreactive though varying in staining intensity. Small neurons were often stained very intensely, while medium-sized to large neurons exhibited moderate staining. Immunoreactive fibers were observed throughout the ganglion and extending toward the dorsal root. This study demonstrates a pChAT-like immunoreactivity in the human peripheral nervous system.