Possible role of elevation of glutathione in the acquisition of enhanced proliferation of mouse splenocytes exposed to small-dose gamma-rays.
OBJECTIVE
To examine the relation between the induction of an increased glutathione level and the elevated proliferative response of mouse splenocytes by a small dose of gamma-rays.


METHODS
Male ICR strain mice, 7 weeks of age, were divided into irradiated and non-irradiated control groups. Irradiation was done with gamma-rays from a 137Cs source at a dose of 50 cGy (1.11 Gy/min). Glutathione content in the splenocytes was measured using a modified spectrophotometric technique. Concanavalin A (Con A)-induced proliferative response of the splenocytes after whole-body gamma-ray irradiation was estimated from the 3H-thymidine incorporation into the cells.


RESULTS
The glutathione level in mouse splenocytes increased 2 h after whole-body y-ray irradiation at 50cGy, peaked at 4h and thereafter decreased almost to the zero-time level by 12-h postirradiation. A significant enhancement of Con A-induced proliferation was observed in the splenocytes obtained from the whole-body-irradiated animals between 2h and 6h post-irradiation. Glutathione exogenously added to splenocytes obtained from normal mice enhanced the Con A-induced proliferation of splenocytes in a dose-dependent manner. This enhancement was completely blocked by buthionine sulfoximine, a specific inhibitor of the de novo pathway of glutathione synthesis.


CONCLUSIONS
The induction of endogenous glutathione immediately after low-dose gamma-ray irradiation is at least partially responsible for the enhancement of immune function, and may throw light on the mechanisms of carcinostatic effects induced by low dose ionizing radiation.
Kojima
S
S
Faculty of Pharmaceutical Sciences, Science University of Tokyo, Noda-shi, Chiba, Japan. kjma@rs.noda.sut.ac.jp
Matsumori
S
S
Ishida
H
H
Yamaoka
K
K
D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002588:Cesium Radioisotopes; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005720:Gamma Rays; D005978:Glutathione / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D013154:Spleen / Q000166:cytology* / Q000528:radiation effects*; D013997:Time Factors
D002588:Cesium Radioisotopes; D011838:Radiation-Sensitizing Agents; D003208:Concanavalin A; D019328:Buthionine Sulfoximine; D005978:Glutathione