IL-1beta, TNFalpha and IL-6 induction in the rat brain after partial-body irradiation: role of vagal afferents.
OBJECTIVE
To evaluate the central nervous system neuroimmune and inflammatory responses during the prodromal phase of the acute irradiation syndrome in rat brains after partial-body exposure (head-protected) and to investigate the potential neural signalling pathways from the irradiated periphery to the non-irradiated brain.


METHODS
The study included four groups of rats: one irradiated group and one sham irradiated group, each containing non-vagotomized and vagotomized rats. In vagotomized rat groups, the subdiaphragmatic vagal section surgery was carried out 45 days before the irradiation exposure. The rats were partial-body irradiated with the head shielded with (60)Co gamma-rays to a dose of 15 Gy. They were sacrificed 6 h after the end of exposure. The hypothalamus, hippocampus, thalamus and cortex were then collected, and the concentrations of IL-1beta, TNFalpha and IL-6 in each were measured by ELISA assays.


RESULTS
Six hours after irradiation, IL-1beta levels had increased in the hypothalamus, thalamus and hippocampus, and TNFalpha and IL-6 levels had increased significantly in the hypothalamus. Vagotomy before irradiation prevented these responses.


CONCLUSIONS
It was concluded that the hypothalamus, hippocampus, thalamus and cortex react rapidly to peripheral irradiation by releasing pro-inflammatory mediators. The results also show that the vagus nerve is one of the major ascending pathways for rapid signalling to the brain with respect to partial body irradiation.
Marquette
C
C
IRSN BP no. 17 F-92262 Fontenay aux Roses cedex France. christel.marquette@irsn.fr
Linard
C
C
Galonnier
M
M
Van Uye
A
A
Mathieu
J
J
Gourmelon
P
P
Clarençon
D
D
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000503:physiopathology* / Q000528:radiation effects*; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D016207:Cytokines / Q000096:biosynthesis*; D004660:Encephalitis / Q000378:metabolism*; D005720:Gamma Rays / Q000009:adverse effects; D006624:Hippocampus / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D007031:Hypothalamus / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D007375:Interleukin-1 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008297:Male; D009434:Neural Pathways / Q000503:physiopathology / Q000528:radiation effects; D015213:Neuroimmunomodulation / Q000528:radiation effects*; D051381:Rats; D013788:Thalamus / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014628:Vagotomy; D014630:Vagus Nerve / Q000503:physiopathology* / Q000528:radiation effects / Q000601:surgery*; D014916:Whole-Body Irradiation / Q000379:methods
D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha