I~t~rnoti~~~iJournaif ~~~~lf~~ogy Vol. 21. No. 4, pp. 463--1@5, 1991 ~2~7519~1 $3.00 + 0.00 Prinled m Great Brifnin Pergamon Pew plc 0 1991 Awlrdion zyxwvutsrqponmlkjih .So c ie fyfo r Pa ra sito lo g y RESEARCHNOTE zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA EFFECT OF PLASMODIUM BERGlfE1INFECTION AND CHLOROQUINE ON THE HEPATIC DRUG METABOLIZING SYSTEM OF MICE PRATIMA SRIVASTAVA,* L. M. TRIPATHI,*S. K. PURI,? G. P. DUTTA~ and V. C. PANDEY*$ Divisions of *Biochemistry and tMicrobiology, Central Drug Research Institute, Lucknow-226001, India zyxwvutsrqpon (Received 2 January 1991; accepted 8 March 1991) Abstract-Sruvnsmvn P., TRIPATHI L. M., PWRI S. K., zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML DUTTA G. P. and PANDEY V. C. 1991. Effect of Plusmodium berghei infection and chloroquine on the hepatic drug metabolizing system of mice. International Journalfor Parasitology 21: 463466. The hepatic microsomal mixed-function oxidase (MFO) system was markedly impaired during Plasmodium berghei infection in mice. Cytochrome P-450 and other mono-oxygenases, viz. aniline hydroxylase, aminopyrine-N-demethylase and benzo(a)pyrene hydroxylase, were significantly decreased while microsomal heme showed a four-fold increase at peak parasitemia (> 50%). Oral treatment with chloroquine (16 mg kg -’ body wt for 4 days) of P. ~erg~ej-inf~t~ mice cleared the parasitemia within 72 h and almost normalized the altered levels of MFO indices, a week after cessation of treatment. The findings were further supported by the isoenzymic profile and drug-binding properties of terminal mono-oxygenase, cytochrome P-450. INDEX KEY WORDS: Mixed-function oxidase: Plasmodium berghei; chloroquine; cytochrome P-450. THE hepatic-microsomal mixed-function oxidase (MFO) system plays an important role in the meta- bolism and disposition of drugs, xenobiotics, etc. (Kato, 1977). In certain situations of pathological stress, including some parasitic and microbial in- fections, the status of the hepatic drug-metabolizing system of the diseased animals has been reported to undergo alterations (Tekwani, Shukla & Ghatak, 1988). Malaria is known to produce hepatomegaly, disturbing the normal physiological function of the liver and hence it would be expected that the MFO system will also be affected (Alvares, Veng, Scheibel & Holhngdale, 1984). However, no detailed information exists regarding the changes in the isoenzymic profile of cytochrome P-450 and its binding behavior with different substrates in infected and chloroquine-cured mice. The present investigation reports on the isoenzymic profile of cytochrome P-450, the effect on its binding capacity with different substrates and also the status of the MFO system during PIas~odiu~ berghe~ infection in mice, before and after treatment with chloroquine KQ). Plasmodium berghei K173 strain infection was maintained in albino mice (Swiss strain), using the method of Puri, Agarwal, Kazim & Dutta (1979). Oral treatment with CQ (16 mg kg-’ body wt for 4 days) was given to normal and P. berghei (parasitemia ‘Y 12-15%)-infected mice. The postmitochondrial (11 ,OOOg; 20 min; supernatant) and microsomal frac- 1 To whom all correspondence should be addressed. tions (105,OOOg; 60 min; pellet) from mouse livers were prepared as previously described (Saxena, Saxena, Dutta, Ghatak & Pandey, 1987). Aniline hydroxylase (AH) (Imai, Ito & Sato, 1966), aminopyrine-N-deme- thylase (AND) (Cochin & Axelrod, 1959) and benzo- (a)pyrene hydroxyiase (BPH) (Dehnen, Tomingas & Roes, 19’73) were dete~ined in the I l,OOOg super- natant while cytochrome P-450, cytochrome b, and heme (Omura & Sato, 1964) were estimated in the microsomal fraction._Drug binding studies were carried out according to a slight modifi- cation of the method of Schenkman, Sligar & Cinti (198 1). Polyacrylamide gel electrophoresis (PAGE) was carried out according to Moore, Welton & Aust (1978) except that gels were left overnight at room temperature to reduce the residual SO,‘- groups after casting Gels were stained by 3,3’, 5,5’-tetramethyl benzidine (Sigma) for hemeperoxidase activity as described by Thomas, Ryan & Levin (1976). Photo- graphy of the gels was carried out within 2 h of staining. Protein was estimated according to Lowry, Rose- brough, Farr & Randall (1951). The data were analyzed for statistical significance using Students ‘t’ test; P values of less than 0.01 were considered significant. The infections in mice resulted in deleterious effects leading to death after about one week, with para- sitemia reaching up to 60%. The terminal mono- oxygenase (cytochrome P-450), aniline hydroxylase, aminopyrine-N-demethylase, benzo(a)pyrene hy droxylase and cytochrome b, were inhibited to a considerable extent even at the lowest level of para- 463