Acute and protracted radiation effects on small intestinal morphological parameters.
OBJECTIVE
To compare the responses of small intestinal morphological parameters after acute and protracted doses of radiation.


METHODS
Male C57BL6 mice were examined 6, 24 and 72 h after whole body gamma-irradiation, given either as an acute 5 Gy dose, or as a protracted (continuous) dose of 20 cGy per day for 25 days to a total dose of 5 Gy. Many different structural parameters at both the light microscopical and ultrastructural levels were assessed quantitatively.


RESULTS
At different time points following both schedules there were changes in the number of villous enterocytes, goblet cells, lamina propria cells and mitotic figures. Ultrastructural changes occurred in the epithelium. Many of the parameters that showed changes following the protracted schedule appeared to be returning to normal within 3 days of the cessation of radiation, a finding which was in contrast with the acute dose. The protracted schedule produced increases in the number of Paneth cells and in the length of enterocyte microvilli.


CONCLUSIONS
Many of the responses that occurred after the protracted schedule suggest that adaptive mechanisms may be being triggered following persistent exposure to radiation.
The Queen's University of Belfast, School of Biomedical Science/Anatomy, Medical Biology Centre, Northern Ireland.
P C
PC
Brennan
K E
KE
Carr
T
T
Seed
J S
JS
McCullough
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D001160:Arterioles / Q000473:pathology / Q000528:radiation effects; D003594:Cytoplasmic Granules / Q000473:pathology / Q000528:radiation effects / Q000648:ultrastructure; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D007413:Intestinal Mucosa / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure; D007421:Intestine, Small / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008938:Mitosis / Q000528:radiation effects; D009130:Muscle, Smooth / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure; D009197:Myenteric Plexus / Q000473:pathology / Q000528:radiation effects; D019047:Phantoms, Imaging; D014916:Whole-Body Irradiation