• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.27-36
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• 1984

It was previously reported that red ginseng extract inhibited carcinogenesis by urethan, DMBA and aflatoxin $B_1E (Cancer Detection and Prevention, 6: 515-525, 1983). In an attempt to investigate the mechanism of the anticarcinogenic effect of ginseng, we assayed natural killer (N.K) activity in mice treated with urethan and benzo(a)pyrene. In our experiment newly born Swiss Webster mice, less than 24 hrs. old, were given a single subcutaneous injection of lmg of ure-than and 40ug of benzo(a)pyrene. The mice had been administered with ginseng since weaning, and sacrificed at various intervals. Major organs were examined both, with the naked eye and microscopically. N.K. activity of spleen cells was analyzed in a 12-hour $^{51}Cr^-release$ assay against YAC-1 cells. Administration of ginseng resulted in an increase of N.K. activity by $18\%$ at 4 weeks, $20\%$ (P < 0.05) at 6, $29\%$ (P < 0.05) at 12, and $13\%$ at 24 following a single injection of urethan. At the same time, significantly lower incidences of lung adenoma were noted at 6 weeks $(50\%)$ and 12 weeks $(27\%)$ following the administration of ginseng to urethan-injected mice. This result indicates that the enhancement of N.K. activity by ginseng makes a contribution to its anticarcinogenic effect. On the hand, N.K. activity was suppressed by benzo(a)pyrene during the time span of this experiment and it almost returned to the level of controls following the adminsitration of ginseng. However, the lung adenoma induced by benzo(a)pyrene began to occur at 48 weeks in which N.K. activity had naturally declined to a very low level in all experimental mice, and administration of ginseng did not decrease the incidence. In explanation of this result, we might propose that the recovery of the N.K. activity by ginseng had little effect on the incidence of lung adenoma because of the long latent period of carcinogenesis by benzo(a)pyrene. In conclusion, these results suggest that the anticarcinogenic effect of ginseng in urethan-treated mice may be related to the augmentation of N.K. activity.