Endocrine cells in rectal biopsy specimens from patients with familial amyloidotic polyneuropathy.

Background: A decreased amount of duodenal endocrine cells has recently been found in patients with familial amyloidotic polyneuropathy (FAP), and it has been suggested that this may contribute to the development of the gastrointestinal symptoms. The present study was performed to establish whether the endocrine cells in the lower gastrointestinal tract are also affected.
Methods: The endocrine cells in rectal biopsy specimens from 13 patients (7 women and 6 men) with FAP were investigated by means of immunocytochemistry and computed image analysis. These specimens were taken early during the disease. As controls, rectal specimens from 13 patients (7 women and 6 men) with rectal bleeding caused by haemorrhoids or polyps were included.
Results: The amount of both serotonin- and pancreatic polypeptide (PP)-immunoreactive cells was significantly decreased compared with the controls. There was no significant difference between patients and controls with regard to the amount of chromogranin A-, polypeptide YY (PYY)-, enteroglucagon- and somatostatin-immunoreactive cells.
Conclusion: It has been suggested that serotonin depletion may contribute to the development of the severe constipation encountered in FAP patients in early stages of the disease. This constipation may promote bacterial overgrowth in the small intestine, with diarrhoea and malabsorption as a result.