Cholinergic and nitrergic interneurones in the myenteric plexus of the human colon
- 1Department of Surgery and Centre for Neuroscience, Flinders University, Adelaide, Australia
- 2Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
- Correspondence to:
Associate Professor D Wattchow, Department of Surgery, Flinders Medical Centre, GPO Box 2100, Adelaide 5001, Australia;
- Accepted 11 September 2001
Background: Myenteric interneurones are involved in the reflexes that control the motility of the human colon.
Aims: The distribution of choline acetyltransferase (ChAT) and nitric oxide synthase (NOS) immunoreactivity in myenteric interneurones was investigated in this study.
Methods: DiI (1,1`- didodecyl 3,3,3`,3`-indocarbocyanine perchlorate) was applied to the myenteric plexus of the human colon followed by organotypic culture. Retrogradely labelled neurones, with projections longer than motor neurones (>10 mm), were studied to exclude motor neurone populations. ChAT and NOS immunoreactivity was then determined in the interneurones.
Results: We found that 90% of interneurones projecting orally contained ChAT and none contained NOS. Ninety five per cent of descending interneurones were labelled with ChAT and/or NOS antisera; 46% contained NOS immunoreactivity alone, 20% contained ChAT immunoreactivity alone, and 29% contained both ChAT and NOS. Anally directed interneurones had significantly longer projections than orally projecting interneurones.
Conclusions: Nearly all interneurones contain either NOS or ChAT immunoreactivity. Orally projecting interneurones are of two types: 90% contain ChAT alone and the remainder contain immunoreactivity for neither ChAT nor NOS. There are three main types of anally projecting interneurones: the largest, which contains NOS but not ChAT, and the two smaller classes which contain ChAT and NOS, and CHAT alone.
- ChAT, choline acetyltransferase
- DiI, 1,1`- didodecyl 3,3,3`,3`-indocarbocyanine perchlorate
- NOS, nitric oxide synthase
- VIP, vasoactive intestinal peptide
- TK, tachykinins