Absence of protective role of afferent nerves in early intestinal mucosal alterations induced by abdominal irradiation in rats.
OBJECTIVE
To assess the early effects of primary afferent nerve suppression by systemic treatment with the neurotoxin capsaicin in an acute model of abdominal irradiation in rats (10Gy, gamma).


METHODS
Changes in myeloperoxidase (MPO) activity, calcitonin gene-related peptide (CGRP) tissue content, number of mast cells and apoptotic cells were determined in jejunum and ileum in four groups of rat male Wistar (vehicle sham-irradiated, vehicle irradiated, capsaicin sham-irradiated and capsaicin irradiated) at 1 and 3 days post-irradiation.


RESULTS
In vehicle irradiated rats, CGRP was significantly increased from the first day after irradiation in jejunal mucosa; MPO activity increased in both segments at day 3 but not at day 1 after irradiation; the number of detectable mucosal mast cells dropped to nearly zero on days 1 and 3, while the apoptotic cells in the intestinal mucosa were significantly increased at day 1. Similar results were obtained for mast cells and apoptosis in capsaicin irradiated rats as compared to capsaicin sham-irradiated rats, while MPO activity was significantly increased and CGRP concentration in jejunal mucosa significantly decreased from the first day in these rats in comparison with capsaicin sham-irradiated rats.


CONCLUSIONS
Intestinal sensory innervation seems not to have a major protective role against a radiation-induced intestinal inflammatory reaction.
Institut de Protection et de Sureté Nucléaire, Digestive Radiobiology Unit, Fontenay-aux-Roses, France. celine.picard@ipsn.fr
C
C
Picard
J
J
Wysocki
C
C
Linard
R
R
Garcia-Villar
L
L
Bueno
N M
NM
Griffiths
J
J
Fioramonti
D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology; D002452:Cell Count; D003714:Denervation; D004435:Eating / Q000528:radiation effects; D007082:Ileum / Q000294:innervation / Q000378:metabolism / Q000528:radiation effects; D007413:Intestinal Mucosa / Q000294:innervation* / Q000378:metabolism / Q000528:radiation effects*; D007583:Jejunum / Q000294:innervation / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D008407:Mast Cells / Q000473:pathology / Q000528:radiation effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects*; D009195:Peroxidase / Q000378:metabolism; D011833:Radiation Injuries, Experimental / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D017833:Visceral Afferents / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects*
D009195:Peroxidase; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin