Molecular amt Biochemical Parasitoh~gy. 45 I'19911 1-8

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Elsevier MOLBIO 01462

The schistosomicidal compound Ro 15-5458 causes a reduction in the RNA content of Schistosoma mansoni F e l e k e E s h e t e * a n d J a m e s L. B e n n e t t Department of Pharmacology and To.ffcolo,ey. Mh-hl~an State L~niversitv. East Lansing, MI, U.S.,4

(Received 18 Apnl 1990- accepted 4 September 1990~

The effect of Ro 15-5458 ( 10-2-(diethylamlno)ethyl-9-acridanone(2-thiazolin-2-.~I lh~drazone i on the steady-state RN A le~els of Schistosoma mansoni *as studied after dosing the host with 15 mg kg-I and retrieving parasites. Total RNA content of parasites recovered from the host 12, 72 and 96 h after dosing was reduced by 14. 30 and 41%. respectively. Quantitative filter hybridization

of blots of RNA extracted from treated and control parasites with specific probes indicated a decline in actin and superoxide dismutase mRNA as well as rRNA of treated parasites. The decline was observed 12 h after dosing. 48 h before parasites showed drug-induced changes in other ~,ital biological processes [8]. A prominent drug-induced reduction ~,as seen on the 1.9 kb actin mRNA compared to the 1.4 kb. The same dose of the drug did not alter the actin mRNA content of the host liver. Simllarl.~, the administration of the inactive structural analogue Ro 21-6787 110-2-(diethylamino)eth)I-9-acndanone) was without an~ effect. We propose that the actions of Ro 15-5458 and/or its products are directed towards the inhibition of the expression of parasite genes. Key words: Schistosoma mansoni Ro 15-5458; Dru~ effects; Actin mRNA: Reduction m RNA content

Introduction At present, chemotherapy is the most effective means in the short-term control o f schistosomiasis [1]. Since the parasites that cause this disease multiply outside the human host, the worm burden and oviposition are crucial for the perpetual cycle o f the infection. Drugs reduce both the worm burden and egg excretion, thus contributing to a decline in both the intensity and prevalence of infection by reducing the population o f infected snails [2]. Currently, however, few chemotherapeutic agents are available for the treatment o f schistosomiasis, and the future of this approach is threatened by the possible emergence o f drug reCorre_~pondence address: James L. Bennett, Dept, of Pharma-

cology and Toxicology, Michigan State Universit),. East Lansing, M! 48824, U.S.A. *Present address: Department of Microbiology, School of Medicine. 203, Sherman Hall. State Uni~.ersity of Ne~. York, Buffalo, NY 14214, U.S.A. Abbreviations." SOD. superoxide dismutase: SSC, saline

sistant strains of the parasites [3]. Thus, research has to be continued towards the development o f new antischistosomal drugs to c o m p l e m e n t existing drugs or replace those that cease to be effective. One candidate is the potent broad-spectrum schistosomicidal agent Ro 15-5458 [4-7]. As part o f an effort in the development o f Ro 15-5458 as a chemotherapeutic agent, we have sought to evaluate the mode o f its schistosomicidal action. Previous work from this laboratory has suggested a defect in Schistosoma m a n s o n i ' s ability to synthesize proteins after treatment of the host with a 15 nag kg -~ single dose o f Ro 15-5458 [8]. However, the target for this action o f the drug was not established. To this end, we have further characterized the effects o f Ro 155458 on the steady-state levels o f selected parasite gene products. In this report, the results of these experiments have been described. In addition, the data from this work and previous report [8] have been used in formulating a working hypothesis to describe the mode of schistosomicidal action of Ro 15-5458,

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Materials and Methods A Puerto Rican strain of S. tnansoni maintained in laborato~'-reared Biomphalaria ,~labrata and ICR Swis~ Webster female mice I Harlan SpragueDawle~,, Indianapolis, IN) was used as a model in this ~tudy. The method of infection was by intraperitoneal injection of 200-300 schistosome cercariae. Mice infected with the parasites received a 15 nag kg - t single oral dose of Ro 155458 or Ro 21-6787 at 5-6 weeks post-infection+ and parasites ~ere retrieved from the mesenteric and hepatic portal veins as previously described [8]. Mice infected on the same day with the same batch and number of cercariae, but which only received the vehicle, were used as the source of control parasites. Total cellular RNA ~as extracted from both groups of parasites after grinding to a paste in liquid nitrogen essentially as described by Chirg~in et al. [9]. Pol.vlAl + RNA was isolated using oligo

The schistosomicidal compound Ro 15-5458 causes a reduction in the RNA content of Schistosoma mansoni.

The effect of Ro 15-5458 (10-2-(diethylamino)ethyl-9-acridanone(2-thiazolin- 2-yl)hydrazone) on the steady-state RNA levels of Schistosoma mansoni was...
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