C Pharmacology & Toxicology 2000, 87, 258–260. Copyright CPrinted in Denmark . All rights reserved

ISSN 0901-9928

Beneficial Effects of Aluminum on the Progression ofLead-Induced Nephropathy in Rats

Abdul Shakoor, Pawan Kumar Gupta, Yash Pal Singh and Meena Kataria

Division of Pharmacology and Toxicology, Indian Veterinary Research Institute, Izatnagar, Bareilly, UP. 243 122 India

(Received March 16, 2000; Accepted August 16, 2000)

Abstract: We studied the effect of aluminum on lead-induced nephropathy in male albino rats. Five groups of male albinorats were given either water only or lead acetate (125 mg/kg body weight) and/or aluminum chloride (50 mg/kg bodyweight or 100 mg/kg body weight) for a period of 90 days. Aluminum was found to prevent the lead-induced increase inthe relative organ (kidney) weight in a dose-dependent manner. Aluminum also prevented lead-induced increase in plasmacreatinine levels of the treated animals. Estimation of lead concentration in kidneys of different treatment groups revealedthat the net deposition of lead was lower in animals which were given both lead acetate and aluminum chloride simul-taneously. The results showed that aluminum offers some protection against lead-induced nephrotoxicity in a time- anddose-dependent manner.

Lead is an important industrial as well as an environmentaltoxicant and its intoxication chiefly affects the haemopoiet-ic, nervous and renal systems (Stowe et al. 1973). Lead-in-duced renal toxicity has been reported both in experimentalanimals and industrial workers (Wedeen et al. 1975; Huguetet al. 1982; Moser et al. 1995; Oberley et al. 1995) but thereare no reports about any interaction of lead and aluminumon the renal system. Since aluminum is extensively used infood processing and storage and in pharmaceuticals mainlyas antacids and phosphate binders, chances of simultaneousexposure to lead and aluminum have become inevitable(Shakoor et al. 2000). Therefore the present study was con-ducted to explore the possibility of any interaction betweenlead and aluminum on renal function in rats.

Materials and Methods

Lead acetate and aluminum chloride were obtained from QualigensFine Chemicals, Mumbai, India. Thirty young male albino rats (75–85 g body weight, specific pathogen-free) were procured from the Lab-oratory Animal Resource Section of Indian Veterinary Research In-stitute. The animals were housed in an air-conditioned room(23.0∫2.0æ) on 12 hr light/12 hr dark cycles and were allowed accessto food and water ad libitum. The animals were acclimatized to lab-oratory conditions for two weeks and thereafter randomly groupedinto five groups of six animals each. Principles of laboratory animalcare were followed and the handling of animals was made under thesupervision of the Ethics Committee of IVRI (Veterinary Council ofIndia). The assorted animals were given deionized water, lead acetateand/or aluminum chloride as shown in table 1.

The body weight of each animal was monitored at weekly inter-vals. Renal function was assessed by measuring plasma creatinine.Blood samples were collected on day 0, 30 and 90 of the respectivetreatments according to the method described elsewhere (Sorg &Buckner 1964). Plasma was separated and used for determinationof creatinine as per alkaline picrate method (McNeely 1980). Afterday 90 the rats were sacrificed under ether anaesthesia; the kidneys

Author for correspondence: Abdul Shakoor, Post Box 1310, Gen-eral Post Office, Srinagar, Kashmir, India 190001.

were removed, cleaned, blotted dry, weighed and examined for grossabnormalities. A portion of each kidney was fixed in 10% formalinefor histopathological examination. Tissue sections were stained withhaematoxylin and eosin.

A fraction of each kidney (about 500 mg) was taken in a thickwalled glass test tube and treated with 5 ml of nitric acid analyticalreagent for digestion overnight. Following digestion, each samplewas heated in 50 ml beaker on a thermostatically controlled hotplate maintained at a temperature of 90æ, until the volume of con-tents was reduced to 0.5 ml. Each such sample was treated with 5ml acid mixture (3 parts nitric acid and 1 part perchloric acid) anddigested slowly until the perchloric acid reaction was complete. Thiswas indicated by the cessation of generation of copious dense whitefumes. The contents of the beaker were heated until the final volumewas once again reduced to 0.5 ml. The digested samples were cooledand diluted to 10 ml with penta-distilled water (Kolmer et al. 1951).Lead analysis was carried out in Atomic Absorption Spectro-photometer (model AAS 4129; Electronic Corporation of India).

Statistical comparisons of the treated groups with respect to con-trol were performed by ANOVA and Dunnet’s multiple comparisonmethod.

Results

The mean body weights recorded at the end of experimentare presented in table 1. Body weight was suppressed byboth lead salt and aluminum salt treatments (P,0.05). Ob-viously, aluminum offered some dose-dependent protectionagainst lead-induced suppression in body weight. Relativekidney weights of the groups treated with lead acetate aloneor lead acetate and a low dose of aluminum chloride weresignificantly higher than the mean relative kidney weight ofthe control group (P,0.05).

Plasma creatinine levels (mg/dl) of different treatmentgroups have been presented in table 2. Throughout the treat-ment period the plasma creatinine levels of the aluminum-treated rats did not show any significant change as comparedto the control. The mean plasma creatinine concentrations inlead-treated rats on day 30 and 90 of treatment were1.92∫0.05 and 1.88∫0.14 (mg/dl) respectively. These values

259ALUMINUM PROTECTION AGAINST LEAD-INDUCED NEPHROPATHY

Table 1.

Details of metal salt administration, body weights and relative organ (kidney) weights (mean∫S.E., nΩ6) of the male albino rats treatedwith lead acetate and aluminum chloride over a period of 90 days.

Dose (mg/kg body weight) Terminal body weight Relative kidney weightsTreatment group Lead acetate (Pb) Almunium chloride (Al) (g) (g/100 g body weight)

Control Deionized water Deionized water 315.00∫8.50 0.57∫0.18Al ª 100 275.00∫11.20* 0.56∫0.02Pb 125 ª 233.00∫14.10** 0.93∫0.13**PbπAl (L) 125 50 245.00∫19.10** 0.08∫0.01**PbπAl (H) 125 100 270.00∫18.50 0.59∫0.01

Al(L)ΩLower dose of aluminumAl(H)ΩHigher dose of aluminum*ΩP,0.05 **ΩP,0.01, Dunnet’s Multiple comparison.

were significantly higher than their contemporary controlvalues (1.22∫0.10 and 1.26∫0.09 mg/dl, respectively;P,0.05). When low doses of aluminum chloride were ad-ministered with lead acetate, the plasma creatinine concen-tration was significantly higher on day 30 only (P,0.05)while on day 90 no significant change was observed as com-pared to the control. At high dose of aluminum chloride withlead acetate the increase in plasma creatinine concentrationon day 30 was highly significant as compared to the control(P,0.05). At the termination of the experiment, the plasmacreatinine level in the lead plus high dose aluminum treat-ment group was similar to that of the control group.

The lead content (mg lead/g wet tissue) of different treat-ment groups has been shown in table 2. Animals treatedwith lead acetate plus aluminum chloride had significantlylow kidney lead concentration as compared to the animalstreated with lead acetate only (P,0.05).

Histopathologically, no significant morphological changewas observed under light microscope in any of the treat-ment groups, except in those of lead acetate alone-treatedanimals. This group revealed mild cytomegaly and kary-omegaly in renal proximal tubule cells as compared to thecontrol and other treatment groups.

Discussion

The present investigation revealed that aluminum counter-acts the lead-induced depression in body weight in a dose-dependent manner. Such ameliorating effect in lead toxi-

Table 2.

Plasma creatinine levels (mg/dl) and lead concentration of the kidneys (mg lead/g wet tissue) in rats treated with lead acetate and aluminumchloride over a period of 90 days (mean∫S.E., nΩ6)

Plasma creatinine (mg/dl)Treatmentgroup Zero day Day 30 Day 90 Kidney lead (mg/g tissue)

Control 1.35∫0.21 1.22∫0.10 1.26∫0.09 5.38∫1.66a

Al 1.00∫0.21 1.32∫0.25 0.97∫0.11 –––––––––Pb 1.25∫0.38 1.92∫0.05** 1.88∫0.14** 220.00∫29.3b

PbπAl L) 1.03∫0.13 1.81∫0.14** 1.34∫0.19 138.50∫15.7c

PbπAl H) 0.85∫0.16 1.75∫0.10** 1.44∫0.04 98.95∫25.5c

*ΩP,0.05 **ΩP,0.01Values bearing different superscripts differ significantly at P,0.05.

cosis has also been reported for zinc and iron (Cerklewski &Forbes 1976; Suzuki & Yoshida 1979). The relative increasein organ weights of lead-treated animals is believed to reflectan adaptive hypertrophy in which the organs increase in sizein order to meet increased functional demands. This wasalso clear from histopathological examination of the tissuesections under light microscope, which revealed mild cyto-megaly and karyomegaly in renal proximal tubule cells. Thisadaptive change was not seen in the aluminum plus lead-treated rats, which indicates a protective effect of aluminumon renal function.

Screening of plasma creatinine is a significantly more re-liable test for renal function than blood urea nitrogen be-cause of its relative independence from other factors such asdiet, degree of hydration, and protein metabolism (Woo &Cannon 1991). High creatinine values in the plasma of lead-treated animals may be attributed to renal dysfunction in-duced by lead ions. However, aluminum seems to protectlead-induced renal dysfunction in a time- and dose depend-ent manner. Aluminum has been shown to arrest thechronic renal disease in several experiments (Lemlertgul etal. 1986; Shimamura & Okada. 1988). Our results revealedthat aluminum prevents the net deposition of lead in kid-neys. This is presumably consequent to decreased absorp-tion of lead in the presence of aluminum. Further, lead andother metals are deposited in bones and other tissues asmetal phosphate complexes (Sollmann 1957). Depletion ofphosphates by prolonged oral exposure to aluminum mighthave reduced the net deposition of lead in kidneys.

ABDUL SHAKOOR ET AL.260

From this study it may be concluded that aluminumchloride reduces the nephrotoxic effects of lead acetate inrats. Similar protective effect of aluminum in arresting theprogression of adriamycin-induced nephropathy has al-ready been documented (Okuda et al. 1988).

Aluminum is relatively less toxic than lead (Schroeder &Mitchener 1975; Bhat 1997). Lead poisoning is character-ized by anorexia, depressed weight gain, anaemia, nephro-pathy and encephalopathy (Stowe et al. 1973; Goyer 1986).Aluminum toxicity is rare in individuals with normal renalfunction however, frequent exposure to aluminum-contain-ing phosphate binders in patients with renal impairmentlead to hypophosphatemia, osteodystrophy and encephal-opathy (Alfrey et al. 1980).

AcknowledgementsThe authors thank the Director, of the Indian Veterinary

Research Institute, for providing the facilities to carry outthe studies. Special thanks are due to Mrs. Shashi Guptafor her technical assistance and statistical evaluation.

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