Timing in administration of a heat-killed Lactobacillus casei preparation for radioprotection in mice.
A single subcutaneous injection of a preparation of heat-killed Lactobacillus casei (LC 9018), given before or after irradiation, significantly increased the survival rate of mice that had received 8.5-Gy 137Cs whole-body gamma-irradiation. A similar radioprotective effect was observed when LC 9018 was administered within the period from 2 days before irradiation to 9 h after irradiation, the pre-irradiation treatment being slightly better than the post-irradiation treatment. Increases in the weight of the spleen and in the number of endogenous spleen colonies on days 8 and 12 after irradiation suggested that the radioprotective effect was based on enhanced recovery of hematopoietic tissues. The activity of macrophage colony-stimulating factor (M-CSF) in serum was rapidly increased by the treatment and was maintained at the elevated level for 13 days. At the same time, an increased level of M-CSF mRNA was detected in the livers of the treated mice. However, LC 9018 failed to save the lives of mice when administered 3 days after irradiation, although it increased serum M-CSF as effectively as noted above. The small advantage of the pre-irradiation over the post-irradiation treatment was not explained by the increases of metallothionein in the hematopoietic tissues of the treated mice.
Tsuneoka
K
K
Division of Chemical Pharmacology, National Institute of Radiological Sciences, Chiba, Japan.
Ishihara
H
H
Dimchev
A B
AB
Nomoto
K
K
Yokokura
T
T
Shikita
M
M
D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000494:pharmacology; D000818:Animals; D007780:Lacticaseibacillus casei; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D011837:Radiation-Protective Agents / Q000008:administration & dosage* / Q000494:pharmacology
D000276:Adjuvants, Immunologic; C048475:LC 9018; D011837:Radiation-Protective Agents