Effects of Sub-chronic Aluminum Exposure on Renal Structure in Rats

Li　Yan-fei,　Liu　Jian-yu,　,　and　Cao　Zheng

1　College　of　Veterinary　Medicine,　Northeast　Agricultural　University,　Harbin　150030,　China

2　Police　Dog　Technical　School　of　Ministry　of　Public　Security,　Shenyang　110034,　China

Effects of Sub-chronic Aluminum Exposure on Renal Structure in Rats

LiYan-fei1,LiuJian-yu1,2,andCaoZheng1

1CollegeofVeterinaryMedicine,NortheastAgriculturalUniversity,Harbin150030,China

2PoliceDogTechnicalSchoolofMinistryofPublicSecurity,Shenyang110034,China

Toinvestigatetheeffectsofaluminum(Al)exposureonrenalstructureofrats,60Wistarratswererandomlydividedinto fourtreatmentgroupsandwereorallyexposedto0(controlgroup,GC),64.18(low-dosegroup,GL),128.36(middle-dosegroup, GM),and256.72(high-dosegroup,GH)mg•kg-1BWAlCl3indrinkingwaterfor120days.Thebodyweightofdifferentratswas recorded,thekidneypathologicstructureandtheultrastructurewereobserved.Theresultsshowedthatthebodyweightofdifferent ratswasmarkedlylowerinAl-treatedratsthanthoseinGC(P＜0.05;P＜0.01).Aftermassonstaining,thecollagenwasdeposited intherenalinterstitiumandaggravatedwithAldoseincreasesinAl-treatedrats.Underelectronmicroscope,theinfoldingofthe plasmamembranewasslightswollen,themitochondrionwasabundantwithdifferentsizes,themitochondrioncristaewasfused,the microvilluswasswollenandfusedinGH.Ourfindingsindicatedthatsub-chronicAlexposureslowedtheweightofratsandcaused thekidneypathologicdamageinrats.

sub-chronic,aluminumexposed,rat,renalstructure

Introduction

Aluminum(Al)isthethirdmostabundantelement inearthcrustandiswidelyusedindailylife.Alcan accumulateinkidney,brain,bone,liver,etc(Kumar andGill,2009;Linardakiet al.,2013).Kidneyis theimportantexcretoryorganthatexcretesmetabolic waste,generatesurine,andregulatesthebalancesof electrolyteandacid-base(Bolignano et al.,2014). SomeresearcheshaddemonstratedthatAlaccumulatedinanimalbodiescouldinjureandsuppressthe renalstructureandfunction(Bohreret al.,2008),but mechanismhadn'tbeencleared.Inthisexperiment,a ratmodelofAlexposurewasbuiltthroughdrinking waterinordertostudythedamageofAltotherenal structure.

Materials and Methods

Animals and treatments

Atotalof60healthymaleWistarrats(5weeksold) weighed110-120gwereusedafter1weekofthe feedingwithastandarddiet.Theywererandomly allocatedintofourgroups(n=15):controlgroup(GC), low-dosegroup(GL),medium-dosegroup(GM),and high-dosegroup(GH).Theratswereorallyadministratedwith0,64.18,128.36,and256.72mg•kg-1BW AlCl3indrinkingwater(distilledwater)for120days. Ratswerefreelyaccessedtofoodandwater.Thehealthstatusoftheratswasmonitoreddaily,andthe bodyweightoftheratswasrecordedmonthly.

Tissue sampling and processing

After120days,ratsweresubsequentlyeuthanizedby cervicaldislocationandwereweighed.Thekidneys werecollected,about2.0×1.5×0.3cm3sizewasput into10%formaldehydefluidformassonstaining, about1.0×1.0×1.0mm3sizewasputinto2.5% glutaraldehydesolutiontoobservetheultrastructure.

Observation of kidney pathologic structure

Thekidneypathologicstructurewasobservedby massonstainingaccordingtothemethodbyZhang et al(2005).

Observation of kidney ultrastructure

Theultrastructurewasobservedaccordingtothe methodbyYamadaet al(2014).

Statistical analysis

Datawerepresentedasmean±standarddeviation (SD)andanalyzedbyusingone-wayanalysisofthe variance(ANOVA)followedbyStudent'sttest(SPSS 17.0software,SPSSIncorporated,Chicago,IL,USA) consideringtheinteractiveeffectsanddifferences betweenAl-treatedgroupsandGC.P＜0.05was consideredstatisticallysignificantandP＜0.01was markedlysignificant.

Results

Clinical symptoms and body weight

ClinicalsymptomsofthemostAl-treatedratswere anorexia,dreariment,shaggyhair,stumble,astasia, andpaletail.Theserioussymptomswereprincipally shortnessofbreath,dyspnea,andgeneralizedconvulsion.However,thecontrolgroupratsgrewwell.

Thebodyweightofalltheratsincreasedthroughout theexperimentperiod,whilethebodyweightofAltreatedratswaslowerthanthatinGC.Thebody weightoftheratswaslowerinGL(P＜0.05),GMand GH(P＜0.01)thanthatinGC(Table1).

Result of masson staining

ThecollagensinGCwerelocatedmainlyinrenal tubularbasementmembrane,renalcapsule,glomerular mesangialarea,andaroundthesmallbloodvessels (Fig.1).InAl-treatedrats,thecollagenwasdeposited intherenalinterstitiumandaggravatedwithAldose increasesinAl-treatedrats(Figs.2-4).Thecollagen fiberwasgreen,redbloodcellwasorange,and cytoplasmwasred.

Table 1　Body weight changes of rats (g)

Kidney ultrastructure

Thepodocyte,microvillus,nuclearenvelope,rough endoplasmicreticulum,microfilamentandthe mitochondriastructureofthekidneyareshown inFigs.5-8forGCandFigs.9-12forGH.Thedifferentsizes,anditscristaewasfused(Fig.10), andmicrovilluswasslightfused(Fig.11).Microvillus wasswollen,fusedandthestructurewasunclear (Fig.12). damagesofplasmamembrane,mitochondrion, andmicrovilluswereobviousinGH.Theinfoldingofplasmamembranewasslightswollen (Fig.9).Themitochondrionwasabundantwith

Fig. 1　Kidney in rats of GC (masson staining ×400)

Fig. 2　Kidney in rats of GL (masson staining ×400)

Fig. 3　Kidney in rats of GM (masson staining ×400)

Fig. 4　Kidney in rats of GH (masson staining ×400)

Fig. 5　Podocyte of kidney in rats of GC (×4 200)

Fig. 6　Microvillus of kidney in rats of GC (×9 900)

Fig. 7　Mitochondria and nuclear membrane of kidney in rats of GC (×16 500)

Fig. 8　Mitochondria, rough endoplasmic reticulum and microfilament of kidney in rats of GC (×16 500)

Fig. 9　Plasma membrane infolding and nuclear membrane of kidney in rats of GH (×4 200)

Fig. 10　Mitochondria and and microvillus of kidney in rats of GH (×9 900)

Fig. 11　Mitochondria and microvillus of kidney in rats of GH (×9 900)

Fig. 12　Microvillus of kidney in rats of GH (×16 500)

Discussion

Nodeathwasdiscoveredinalltheratsduringthe experiment.However,Al-treatedgroupswereless activethanthatinGC.Theslownessofthebody weightgrowthinAl-treatedgroupsindicatedthatAl couldinhibitthegrowthoftherats.Thesimilarresults werediscoveredinourpreviousresearches(Wang et al.,2012;Zhuet al.,2014).Theresultssuggested thatAlCl3inducedthechangeofclinicalsymptoms andinhibitedthegrowthofbodyweight.

Kidneyisoneoftheprimarytargetorgansofmany chemicalsanddrugs.Thekidneylesionswerecaused bymanyfactors(Mahieuet al.,2009).Jiet al.(2011) foundthatglomerulusshrankinratstreatedwith 100mg•kg-1AlCl3throughnasaldrip.Zhuo(2008) discoveredthatovermuchAlaccumulatedinrats inducedtheswelloftherenaltubules,capillariesand theepithelialcellsoftheproximalconvolutedtubule. Thisstudyshowedthatglomerulus,renaltubular basementmembrane,andrenalinterstitiumweredyed green,redbloodcellwasdyedorange,andcytoplasm wasdyedredbymassonstaining.Theresultsshowed thatsub-chronicAlexposurecouldinducerenal interstitialfibrosis,andtherenalinterstitialfibrosis wasaggravatedwithAldoseincreases.

Inthisstudy,thepathologicaldamageofthekidney focusedonrenaltubularepithelialcells,especially thechangesofmitochondrionandmicrovillus underelectronmicroscope.Themitochondrionwas abundantwithdifferentsizes,themitochondrion cristaewasfused,andthemicrovilliwereslight fused,swollenandfusedinGH.Ourprevious researchesreportedthatAlCl3exposureledto Alaccumulationinkidney,inhabitedthekidney growth,andcausedthepathologicalchangesof glomerulusandrenaltubuleinratsafterkidney hematoxylinandeosinwerestained(Xiaet al., 2013).Theresultsshowedthatsub-chronicAl exposurecouldinducethedamageofthekidney structure.

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S852.2Document code: A Article ID: 1006-8104(2015)-02-0047-05

10January2015

SupportedbytheScienceandTechnologyProgramofHeilongjiangEducationalBureau(12541025);theNaturalScienceFoundationofHeilongjiang Province(C201425)

LiYan-fei(1967-),female,professor,supervisorofPh.Dstudent,engagedintheresearchofveterinarymedicine.E-mail:yanfeili_200@126.com