Comparative protection by desferrioxamine against hepato- and nephro-toxicity induced by azathioprine

Introduction

Although the biochemical mechanism of toxicity to liver and kidney by azathioprine (AZA) have been fairly defined and several hypothesis have been proposed. The most documented hypothesis suggests an involvement of lipid peroxidation (MDA) preceded by glutathione (GSH) depletion. The involvement of peroxidative injury in hepato- and renal toxicity is based on several lines of evidence (1–6) and corroborate the postulated role of MDA in hepatic and renal manifestations. It is also well known that presence of transition metal plays a crucial role in the initiation and propagation of free radicals. A study of biochemical changes in liver and kidney following use of an iron chelator has not been reported.

Objectives

To determine the effects of pretreatment of mice with DFO on the MDA and sulfhydryl contents in the kidney and liver tissues either with AZA or in combination with DFO and role of iron and other transition metals in the initiation and production of reactive moieties; and to assess the effects on the plasma levels of biochemical markers in AZA-treated mice and thus evaluate the possible participation of free radicals in its pathogenesis and possible protection by DFO.

Methods

Six groups of adult male Swiss albino mice were treated as follows. Group I: control group, saline for 5 days by intraperitoneal (i.p.) injection; group II and III: DFO 100 and 200 mg/kg body wt. i.p., for 5 consecutive days; group IV: AZA (100 mg/kg body wt.) as a single i.p. dose on the 5^th day; group V and VI (DFO 100 or 200 mg/kg for 5 days + AZA (100 mg/kg; single dose on 5^th day). A day after the last treatment, blood samples were obtained, and all the animals were sacrificed, the liver and kidneys were excised off the body, and biochemical analyses of tissues were performed. Hepatic and renal status was determined using plasma biochemical markers.

Results

There was a significant increase (P<0.001) in MDA contents after treatment with AZA in both liver and kidney tissues when compared to control. Pretreatment with DFO prevented any increase in MDA contents in both the tissues significantly (P<0.001) but could not keep it to the base line when compared to AZA alone group (Chart A). Treatment of mice for consecutive five days had no significant effect on the levels of NPSH (Chart B) in liver and kidney tissues in comparison to control group. But, AZA at 100 mg/kg i.p. significantly reduced (P<0.001) NP-SH contents in both liver and kidney tissues of treated mice in comparison to control. Pretreatment of mice for five days with DFO afforded no protection against the declining levels of NPSH at both the dose levels, and this decline was significantly (P<0.001 and P<0.01) lower at 100- and 200 mg/kg doses, respectively, in the liver and kidney tissues. Treatment with AZA caused a significant (P<0.001) incline in all the parameters. The levels of plasma biochemical parameters (AST, ALT, LDH and creatinine) were significantly (P<0.001) lower in DFO treatment group from AZA group. Pretreatment with DFO significantly prevented a rise in all biochemical parameters when compared to AZA alone group, but remained significantly elevated than the control group.

Discussion

Our findings suggest that DFO is safe and useful for ameliorating azathioprine-induced hepato- and nephro-toxicity. The protection offered against azathioprine was comparable in preventing a rise in MDA.

However, a decline in NPSH contents in both liver and kidney tissues could not be recovered by either of the test doses of DFO. The plasma levels of aminotransferases, LDH and creatinine that increased significantly by AZA also recovered significantly but could not recuperate to baseline; it seems that DFO pretreatment is more effective in the recovery of LDH and creatinine levels to its baseline in this treatment regimen.