PATHOMORPHOLOGICAL STUDIES ON LEAD POISONING IN WISTER ALBINO RATS WITH SPECIAL REFERENCE TO REPRODUCTIVE TOXICITY AND ITS AMELIORATION
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Date
2010-04
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Sri Venkateswara Veterinary University, TIRUPATI – 517 502,A.P
Abstract
ABSTRACT:
Lead is an abundant, ubiquitous, dangerous and important toxic
environmental contaminant and is of global concern due to its significant
role in modern industry. Lead is the most important poison to the farm
animals and the significant pollution is likely to occur from lead mining,
painted and metallic lead in storage batteries, licking paints / puttyans from
rubbish dumps. Exposure to lead can induce a number of effects including
neuro, hepato and nephrotoxicity, hematobiochemical effect, endocrinal
disturbances, genotoxicity, reproductive toxicity and alters the immune
system.
The present experiment was designed to make a systematic study of
experimentally induced lead poisoning and its amelioration with Ocimum
sanctum in male Wister albino rats at 60 mg/kg bwt / 3 days in a week and
30 mg /kg bwt / 3 days in a week to groups II and III respectively by
mixing in distilled water for 12 weeks. To the groups IV and V in addition
to lead acetate as above mentioned dose, Ocimum sanctum was given at
400 mg / kg bwt/3 days a week / orally for the same duration, with the
objectives of finding out of the effect of lead poisoning on hematobiochemical,
oxidative damage, hormonal assay, reproductive toxicity,
immunological, genotoxicity, gross and histopathological, ultra structural
changes, residual estimation and ameliorative effect of Ocimum sanctum
against lead induced damages.
In addition epidemiological study on lead content in the blood and
milk samples of cattle in five different factory areas as well as tissue
samples of cattle and sheep form different urban areas was carried out.
Specific clinical signs were not observed, except few rats of group
II, III, IV and V that showed almost similar signs in general during the
experimental period as dose dependent manner which included reduced
feed intake, anxiety, loss of muscle coordination, tremor, dizziness etc. In
the present investigation no mortality was observed in any of the treated
group.
Significant (P<0.05) reduction was recorded in the TEC, PCV, Hb
and percent lymphocyte count. Significant increase in the percent
neutrophil count and TLC were observed in all the lead treated groups.
These counts were significantly improved in the OS ameliorated groups
with lower dose of lead acetate (group V).
Significant (P<0.05) decrease was noticed in the CAT, SOD, GPx
activity in liver, kidney and testis of lead treated groups when compared to
control groups. Non significant improvement in these values was observed
in ameliorated groups (V & V) in a dose dependent manner.
A significant (P<0.05) decrease was noticed in T3, T4 and TSH
levels, acetyl cholinesterase activity in brain and significant increase in
serum testosterone and LDH levels in lead treated groups (Group II &
III).The level of T3 and TSH were significantly improved in the OS
ameliorated groups with lower dose of lead acetate (Group V), while the
remaining values were non significantly improved in OS ameliorated
groups.
Significantly (P<0.05) decrease in testicular weight, sperm count
and significant increase in abnormal sperm count were observed in lead
treated groups when compared to control group.
Significant (P<0.05) decrease was noticed in HA titer (log) and
DNCB contact sensitivity score in groups II and III when compared to
control group. In OS ameliorated groups (IV & V) a significant
improvement was noticed in these values.
Significant (P<0.05) increase was seen in micronuclei in PCE cells
of lead treated groups (Group II & III) when compared to control. In OS
ameliorated groups (IV & V) a significant decrease was noticed in these
values.
Histopathlogically, the liver of group II rats revealed sinusoidal
dilatation dilated central vein and focal areas of necrosis, hyper chromatic
nuclei, binucleated cells, karyomegaly. Focal loss of hepatocytes with
moderate MNC infiltration, moderate to severe vesicular fatty change,
extensive bile duct proliferation and fibroblast proliferation around periportal
area. Microgranulomas were observed very conspicuously in lead treated
groups in a dose dependent manner and these lesions were mild in the OS
ameliorated group (Group IV) with higher dose of lead after 6th week of lead
feeding. The changes were gradually reduced and by the end of 10th week, it
regains its normal appearance. Where as in Group V (OS ameliorated group of
lower dose) these changes were less intensive and by the end of 8 to 12 weeks,
liver comes to near normal.
Kidney sections of lead treated rats revealed dose dependent congestion
of glomeruli, mild to moderate hemorrhages, glomerular vacuolation, atrophy
of glomeruli, desquamated tubular epithelial cells, pockets of hemorrhages in
cortex and severe mononuclear cell infiltration were observed by the end of
12th week. All the changes were dose and duration dependent and these
changes were less severe in OS treated groups.
Extensive submeningeal and cerebral hemorrhages and spongiosis,
swollen neurons with severe degenerative changes, glial cell proliferation,
severe demyelinating changes, gliosis, infiltration of MNC, perivascular
infiltration of MNC and necrotic nodules with proliferation of capillaries were
more prominent in cerebral cortex of majority of lead treated groups (groups II
and III) in a dose dependent manner. Cerebellum of rats showed spongiosis,
shrinkage and focal loss of Purkinje cells, rounding and tapering of Purkinje
cells, demyelination and vacuolatory changes in majority of animals at the end
of 10th to 12th weeks in lead treated groups. These changes were
less severe in OS ameliorated groups of higher dose and lower dose (IV & V).
Microscopically, Group II and III lungs revealed congestion, edema,
hyalinised blood vessels and bronchiole, intense emphysema, widening of
interstitial spaces with MNC, edema and RBC, swollen and vacuolated
alveolar epithelial cells, infiltration of alveolar macrophages, peribronchial and
perivascular lymphoid aggregates. Hyperplasia of bronchiolar epithelium in
focal areas and desquamated bronchial epithelial cells were found as constant
lesion by the end of 12th week in a dose dependent manner. These changes
were mild in OS ameliorated groups when compared to corresponding lead
treated groups.
Testis showed interstitial edema, thickened basement membrane of
seminiferous tubules, disruption of basement membrane, separation of
seminiferous tubular epithelium from basement membrane, shrinkage of
tubules, basement membrane with spermatogonial cells, desquamated
seminiferous tubular germ cells, disappearance of Leydig cells and MNC
infiltration in interstitium and presence of multinucleated cells in seminiferous
tubules were conspicuous by the end of 12 weeks.
Pancreas revealed degenerated islets of Langerhans, congested,
thickened and hyalinized blood vessels, hyperplasia of ductular epithelium,
periductular MNC infiltration, necrosis and atrophy of islets, vacuolar
degeneration in acinar epithelium and MNC infiltration between acini,
interlobular hemorrhages, extensive interlobular fibroblast proliferation and
severe necrosis of islets of pancreas were more conspicuous in majority of
animals in lead treated groups (Groups II & III) when compared to control
group by the end of 12th week. These changes were with reduced intensity in
OS ameliorated groups.
Thyroid of lead treated rats revealed dose dependent changes like
hemorrhages, severe desquamation of acinar epithelial cells, and complete
absence of colloid in acini, disruption of acini with absence of colloid and
atrophy of acini were noticed throughout experimental period. Very mild
changes were noticed in Ocimum treated groups.
.
Skin of lead treated groups revealed mild MNC infiltration in dermis,
mild edema in dermis and thinning of epidermis, vacuolar degeneration of
epidermal cells and sebaceous glands, atrophy of hair follicles and hyperplastic
sebaceous glands were more conspicuous in a dose dependent manner. These
changes were in mild intensity in OS ameliorated groups.
Histochemically more intense alkaline phosphatase reaction was noticed
in epithelium and basement membrane of proximal convoluted tubules of
kidney and interstitial tissue and basement membrane of seminiferous tubules
and less reaction in spermatogonial cells of testis of lead fed groups in a dose
dependent manner. Where as a dose dependent decrease in alkaline
phosphatase reaction was noticed in OS ameliorated groups.
Immunohistochemistry was done to detect apoptotic bodies in liver and
kidney by using the monoclonal antibodies against BAX and BCl2 antigens.
The reaction was more pronounced in the hepatocytes around central veins and
peripheral hepatocytes of hepatic lobule of liver, where as in kidney, the
reaction was found in epithelial cells of PCT of lead treated groups in a dose
dependent manner. The reaction was less in OS ameliorated groups.
Ultra structurally, kidneys of lead treated groups revealed swollen
mitochondria with degeneration, fragmented endoplasmic reticulum, increased
number of lysosomes, clumping of nuclear chromatin and Intranuclear electron
dense lead inclusions with different sizes. Where as in liver, increased number
of darkly stained lysosomes, swollen and decreased mitochondria and less
endoplasmic reticulum, clumping of nuclear chromatin in hepatocytes.
Swollen and vacuolated vascular endothelial cells, degenerated myelin sheath,
decrease in mitochondrial density margination and clumping of nuclear
chromatin in brain were noticed in dose dependent manner.
Residual analysis of blood and tissue samples (liver, kidney, muscle and
testis) of all treated groups showed highest lead concentration in kidney
followed by liver, testis and muscle. The highest concentration of lead was
found in group II then followed by group III and other ameliorated groups as a
dose dependent manner. A non significant reduction was noticed in OS
ameliorated groups.
Epidemiologically, the highest lead residuals were found in blood and
milk samples of cows found near batteries factory followed by lamco factory
followed by Neutrine factory, Sugar factory (Puttur) and sugar factory
(Chittoor). Similarly the highest lead concentration was found in kidney
followed by liver and muscle of cattle reared in and around Renigunta. Where
as the highest concentration was noticed in kidney, liver, muscle and testis of
sheep reared in Chittoor followed by Tiruapti urban area.