Persistence of altered 5-hydroxytryptamine turnover following hemibody X-irradiation in the rat distal colon

• Published in: International journal of radiation biology Vol. 80; no. 6; pp. 399 - 411
• Main Authors: Ropenga, A., Combes, O., Chapel, A., Griffiths, N. M.
• Format: Journal Article
• Language: English
• Published: England Informa UK Ltd 01-06-2004; Taylor & Francis
• Subjects: Animals; Base Sequence; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Division - radiation effects; Colon - drug effects; Colon - metabolism; Colon - pathology; Colon - radiation effects; DNA - genetics; Enterochromaffin Cells - metabolism; Enterochromaffin Cells - pathology; Enterochromaffin Cells - radiation effects; Evoked Potentials - drug effects; Evoked Potentials - radiation effects; Gene Expression - radiation effects; Hydroxyindoleacetic Acid - blood; Hydroxyindoleacetic Acid - metabolism; Intestinal Mucosa - drug effects; Intestinal Mucosa - metabolism; Intestinal Mucosa - pathology; Intestinal Mucosa - radiation effects; Male; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Transport Proteins; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Rats; Rats, Wistar; RNA, Messenger - genetics; RNA, Messenger - metabolism; Serotonin - blood; Serotonin - metabolism; Serotonin - pharmacology; Serotonin Plasma Membrane Transport Proteins; Space life sciences; Time Factors; Tryptophan Hydroxylase - genetics
• ISSN: 0955-3002; 1362-3095
• DOI: 10.1080/09553000410001702364

Purpose: Acute gastrointestinal responses to ionizing radiation exposure include a role for 5-hydroxytryptamine (5-HT), but it is not known whether involvement of 5-HT persists and contributes to late effects. The aim was to investigate the acute and later effects of lower hemibody irradiation on 5-HT turnover and the biological effect in the rat distal colon.
Materials and methods: Rats were exposed to 10 Gy lower hemibody X-radiation. 5-HT and 5-hydroxyindole acetic acid tissue levels were measured in the distal colon along with the serotonin re-uptake transporter and tryptophan hydroxylase mRNA. 5-HT-containing cells and crypt cell numbers were estimated in addition to 5-HT-stimulated short-circuit current responses in isolated mucosa. Studies were performed from 3 days to 3 months post-exposure.
Results: During the acute phase, at 3 days post-irradiation, reductions in cell number, tissue resistance, serotonin re-uptake transporter expression and secretory responses to 5-HT were observed. However, at later times when secretory responses were normal, 5-HT tissue levels and enterochromaffin cell numbers were increased.
Conclusions: The results provide evidence that after 10 Gy hemibody irradiation, modifications persist past the acute phase. In particular, 5-HT turnover in the distal colon is altered during a longer period.