Source
Department of Medicine, Royal Postgraduate Medical School, London, England.
Abstract
BACKGROUND:
Calretinin and calbindin-D28k are similar Ca(2+)-binding proteins previously described in specific central neurons and other cells.
METHODS:
The immunocytochemical distribution of these two proteins was studied in the human gastrointestinal tract.
RESULTS:
In gastric and small intestinal endocrine cells, calbindin-D28k immunoreactivity was confirmed, but calretinin immunoreactivity was not found. Nerve cell bodies in both submucous and myenteric ganglia were immunoreactive for calbindin (13% and 38% of total cells, respectively) or calretinin (23% and 21%), some containing both proteins. In nerve processes, calretinin was generally more abundant than calbindin and was found particularly around blood vessels. Calretinin co-localized with immunoreactive vasoactive intestinal peptide, neuropeptide Y, galanin, or substance P in submucous ganglion cells and with substance P in myenteric cells. Calbindin-D28k colocalized with fewer peptides, specifically vasoactive intestinal peptide or galanin in submucous cells. By 8 weeks of fetal development, discrete neuronal localizations for both proteins and for calbindin-D28k in endocrine cells were apparent.
CONCLUSIONS:
In the enteric neuroendocrine system, calretinin and calbindin-D28k are useful markers that may help elucidate Ca(2+)-mediated functions in health and disease.