Persistence of altered 5-hydroxytryptamine turnover following hemibody X-irradiation in the rat distal colon.
Int J Radiat Biol 2009;
80:399-411. [PMID:
15362693 DOI:
10.1080/09553000410001702364]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
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.
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