Light microscopic observations on the in vitro effects of praziquantel on Heterophyopsis continua

Heterophyopsis continua에 대한 praziquantel의 시험관내 효과의 광학현미경적 관찰

This study was carried out to observe in vitro effect of praziquantel on the viability and internal organ changes of Heterophyopsis continua with light microscopy. Metacercariae were collected from the perch, Lateolabrax japonicus, by artificial digestion technique and fed to 2-week old chickens. Adult worms were recovered from the small intestines of chickens 8 days after infection. For working solutions, praziquantel was diluted with TC199 medium at the concentration of 0.01, 0.1, 1 and $10{\mu}g/ml$. To each petri dish containing 10ml of solution, 5~10 worms were introduced and incubated at $37^{\circ}C$. Motlity of worms was observed at 5, 15, 30, 60 minutes, 1, 2, 4 and 6 hours after incubation. For light microscopy, worms were fixed in 10% formalin under cover glass pressure and stained with Semichon's acetocarmine. The results were as follows: 1. In $0.01{\mu}g/ml$ praziquantel, the worms had their mobility until 6 hours post treatment. However, worms in over $0.1{\mu}g/ml$ of praziquantel contracted within 5 minutes and immobilized. 2. Intestine of the worm incubated in $0.001{\mu}g/ml$ praziquantel for 5 minutes was dilated and intestinal wall was thickened. 3. In incubated over $0.1{\mu}g/ml$ praziquantel, pharynx of the worm protruded out from oral sucker. 4. The lowest effective lethal concentration of praziquantel on H. continua was $0.1{\mu}g/ml$. The worms exposed to the drug were observed to be immobilized immediately after incubation in solutions of over $0.1{\mu}g/ml$ concentration. All of the worms in early period showed severe contraction and those in late period showed severe dilation.