Gonad dysplasia in mice infected with Neodiplostomum seoulense

초록

Neodiplostomum seoulense (Digenea: Neodiplostomidae) is an intestinal trematode of humans and rodents in the Republic of Korea. The human infection was first discovered in a young man who consumed the viscera of undercooked snakes. He complained of severe gastrointestinal troubles and eosinophilia. This fluke is now known to be highly pathogenic to mice and all but a few infected mice die within 21 days after infection. In order to reproduce N. seoulense-resistant mice, we tried to mate male and female mice that survive against the infection. However, we met difficulties in reproducing their offspring. In relation to this loss of reproducibility, we found severe gonad dysgenesis in both sexes of mice. When each individual of male and female BALB/c mice was infected with 200 N. seoulense metacercariae and mated between surviving mice after 8 weeks, it was revealed that their genital organs were shrunken in size and their weight became lowered, and sex hormone concentrations in sera were significantly decreased. In addition, the degenerated gonads were shown to have an increase in apoptotic germ cells. On the other hands, castor oil feeding to mice or infection with other intestinal trematodes did not induce such a gonad dysgenesis, although they underwent severe diarrhea like in N. seoulense infection. Accordingly this study suggests that the loss of reproducibility in N. seoulense-infected mice may be due to severe gonad degeneration, retarded production of sex hormones, and an increase of apoptotic cells in the gonad.