OESOPHAGOSTOMUM DENTATUM - POPULATION-DYNAMICS AND SYNTHESIS OF PROSTANOIDS BY HISTOTROPIC STAGES CULTURED IN-VITRO

The dynamics of production and excretion of prostanoids by histotropic larvae of Oesophagostromum dentatum and the role of prostanoids for t he development of O. dentatum were studied under in vitro conditions. In control cultures fourth stage larvae (L4) were first seen on Day 7 of in vitro cultivation. Their numbers steadily increased until Day 21 of in vitro cultivation. Thereafter, the numbers of IA no further inc reased. The continuous presence of inhibitors of prostanoid synthesis such as acetylsalicylic acid (ASA, 5.6 mmole/liter) or indomethacin (I NDO, 1.4 mmole/liter) in the culture medium blocked the development to L4 almost completely. When ASA was given first on Day 13 of in vitro cultivation L4 counts still increased during the following 4 days. How ever, the numbers of larvae which reached the L4 stage in these cultur es was reduced to 65% of that in control cultures. Resumption of devel opment to L4 was seen after the withdrawal of INDO in cultures treated with this drug until Day 13 of in vitro, cultivation. Larvae and supe rnatants were collected separately on Days 7, 14, 21, or 28 of ill vit ro cultivation and larvae were homogenized. The presence of prostaglan din (PG) E2, PGD2, PGF2 alpha, 6-keto-PGF1 alpha and thromboxane (TX) B2 was assayed radioimmunologically in homogenates and supernatants. I n the homogenates only PGE2 and PGD2 were regularly detected. The tota l amount of PGE2 and PGD2 in the homogenates significantly increased w ith the increase in L4 numbers, whereas the homogenate protein-based v alues did not. In addition to PGD2 and PGE2, PGF2 alpha and TXB2 were found in the supernatants. PGE2 accounted for about 50% of the prostan oids in the supernatants on Day 7 of in vitro cultivation but was gene rally absent thereafter. After 14, 21, and 28 days of in vitro cultiva tion TXB2 was the most prominent single prostanoid in the supernatants . PGD2 was found in the supernatants only after 7 and 28 days of in vi tro cultivation. PGF2 alpha was present in decreasing amounts in the s upernatants throughout the cultivation period. In conclusion, histotro pic larvae of O. dentatum produce and excrete mediators of the prostan oid type which may serve as endogenous hormone-like growth factors. (C ) 1995 Academic Press, Inc.