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Effect of lead on zinc content of body organs, bone and serum of rats
Chemosphere, Vol.lO, No.9, pp 1067 - i072, 1 9 8 1 Printed in Great Britain
0045-6555/81/091067-06~02.00/0 ~)1981 Pergamon Press Ltd.
EFFECT OF LEAD ON ZINC CONTENT OF BODY OMGANS, BONE AND SERL~I OF RA'I~
JAI RAJ BEHARI Industrial Toxicology Research Centre, Post Box 80, Lucknow, INDIA
Toxic effects of heavy metals such as lead, mercury and cadmium are influenced by the essential trace elements occuring in the body. The ingestion of the toxic metals or their salts even in the low concentration 81ters the metabolism of these trace elements (I). Zinc is an antagonist to lead and its protective role in reducing the uptake and metabolic effects of lead are now well recognised (2-4). The changes in the levels of trace elements in the body can be useful for early detection of heavy metal intoxication.
The present
investigation deals with the effects of lead on the distribution of zinc in the body organs bo~eand serum of rats. MATERIALS AND M~THODS Sprague Dawley rats fed on Altromin pellet diet and water ad libitum were used in the study.
They were given 50 mg/kg, Pb as Pb(CH3CO0 ~.
3H20 (E. Merck) dispensed in 4 ml of normal saline intraperitoneally daily for 6 days. the saline.
The control animals received an equal volume of
The body weight was recorded daily and the animals
were killed on 8th day.
Blood was collected from heart for serum
separation and in heparinised polysterolvials for lead determination.
Liver, kidneys, testis and femur bone were collected,
cleaned free of extraneous material and weighed.
1067
1068
The tissues were fridge-dried and weighed amount was digested with nitric acid in Perkin Elmer Autoclave III at 145°C under pressure for 45 minutes.
The digested material was raised to a volume
and further diluted appropriately for the determination of zinc(5), serum, was suitably diluted and used for the estimation of zinc directly in alr-acetylene flame of Perkin-Elmer atomic absorption spectrophotometer
303 by the method of standard addition at 213.9 nm.
For blood lead determination,
50jul of blood was mixed with two
volumes of 5% Triton X-tO0 and three vokumes of deionised water or lead standards corresponding to O.&, 0.8 or 1.2 ng Pb/20 p l in the final volume.
Twenty]ul of the sample was injected into the Perkin
Elmer heated graphite atomizer (HGA 76-B) attached to a Perkin Elmer atomic absorption spectrophotometer 420 and analysed for lead (6) at 283.3 nm using following operating programme : Drying
Ashing
Atomization
Burnout
Time (Sec)
35
30
8
2
Temp.(O°C)
100
600
2250
2500
Bone digest was appropriately diluted and 20 p l was injected into the furnace for the analysis of lead by the method of standards addition using the same programme. RESULTS AND DISCUSSION The levels of lead in blood & bone and
~hose of zinc in liver,
kidney, testis, bone & serum are shown in tables I and 2 respectively.
1069
Table 1: Lead content of blood and bone of rats after daily administration of lead acetate for six days.
C on trol
Experimental
Hlood
3 •57+--0.40 (5)
490.8+-31.89a (5)
Bone
0.149+-0.03 (6)
220.6+-19.74a (6)
Table 2: Zinc content in liver, kidney, testis, bone and serum of ra~ after daily admi~:istration of lead acetate for six days.
Control
Experimental
Liver
124.55+2.10 (6)
152.93+_4.65b (5)
Ki~ey
104.10+2.11 (6)
96.38+--I.57 C5)
Testis
187.16+-2.72 (5)
202.74+4.96 (6)
Bone
202.19+--3.57
178.74+2.8 c
WW
(5) Serl~n
126.9+-4.81 (5)
(5) 78.87+_1.37a (4)
* Aag/dl. *w ~I~/~ dry weizht ~sch value represents the mean + S.E. ap&o.o01, bp&Oo01, COLO.05_ when coz:psred to control as evalu~ted by Students' 't' test.
Io7o
The uptake of lead in bone and blood of the rats treated with lead acetate was significantly increased.
The level of zinc increased
significantly in liver and it remained unaffected in kidneys and testis on trea~tment with lead acetate. However the concentration of zinc in serum and bone decreased significantly upon treatz~ent with lead. The nutritional
status has a profound effect on the response
of an organism towards a dose of poison like lead (7) and the involvement of trace elements in the body organs play an important role in influencing its toxici~'.
Zinc is kno~,rn to have influence
in reducln~ the uptake and metabolic effects of lead such as inhibition of S -aminolevulip~c acid dehydratase in blood(2,4,8,9).
The
diets containing high levels of both lead and zinc when fed to rats have been shown to result in markedly reduced ~ - i n a r y S - A L A
concen-
tration as compared to levels produced by corresponding diets containing high lead alone (10). It has also been found that the orotection provided by zinc against lead toxicit ., i n c r e s s ~ with the level of zinc supplimentatio:,(3).
The present r:sults indicate that there
is an involvement of zinc in the body in influencin~ lead toxicity resultin~ in mobilization of zinc from bones and soran ~hich is at least partially taken ~o by the liver. This would su[~port the view that the antagonistic effects of zinc in lead intoxication is due to its interf:rence in lead absorption and that zinc and lead compete for similar bindlns sites on metallothionein llke proteins.
It has
also been shush that increased zinc intake caused increased renal and hepatic metallothionein lesdinz to detoxi~ication through lead binding in this form (11).
lO71
S~4ARY Effect of lead exposure on the distribution of zinc in the body organs, bone and serum of rats was investigated, to understand the role of zinc against lead exposure.
Zinc content of liver was
increased and that of serum and bone was decreased on exposure to 50 mg/kg Pb as lead acetate intraperitoneally daily for six days. It is possible that lead and zinc compete for binding sites in the liver on some metallothlonein like proteins. A CYdqOWTuEDGF/,~NfS The author is grateful to the German Academic Exchange Service for providing a Scholarship and to the Director, Institute for Pharmacology and Toxicology in Mannheim, University of Heidelberg (FRG) where the work has been done.
Thanks are due to Mr H. Dick
for technical assistance. REFERENCES 1)
Petering, H.G. (1978). Environ. Health Perspect, 25, 141-145.
2)
Cerklewski; F.L. and Forbes, R.M. (1976). J. Nutr. 106,688-~6
3)
E 1 G a z z a r R.M., Finel~; V.N., Boiano J. and Petering, ~.G. (1978). Toxicology Letters ~, 227-234.
4)
Finelli, V.N., Klauder, D.S., ~araffa, M.A. and Petering, H.G. (1975). Clin. Chem. ~ , 30)-51~.
5)
Parker, M.M., Humoller, F.L. and Mahler, D.J.(1967). Clin. Chem. 13, 40-48.
6)
Fernandez, F.J. (1975). Clin. Chem. 21, 558-561.
7)
Levander O.A. (1979), Environ. Hlth. Perspect. 29, 115-125.
1072
8)
Border, E.A., Cantrell, A.C., and Kilore-Smith T.A. (1976). Brit. J. Ind. Med. 33, 85-87.
9)
Haeger-Aronsen, B., Abdulla, M. t and Schutz, A. (1976). Arch. Environ. Health 31, 215-220.
10) Thawley, D.D., Willoughby, R.A., McSherry, B.J., MacLeod, G.K. Maekay, K.H. and Mitchell W.R. (1977) Environ. Res. 14, 463-475. 11) Bremner, I. (~974), O. Eev. Biophys. ~, 75. (Received in Japan 16 July 1981)
0045-6555/81/091067-06~02.00/0 ~)1981 Pergamon Press Ltd.
EFFECT OF LEAD ON ZINC CONTENT OF BODY OMGANS, BONE AND SERL~I OF RA'I~
JAI RAJ BEHARI Industrial Toxicology Research Centre, Post Box 80, Lucknow, INDIA
Toxic effects of heavy metals such as lead, mercury and cadmium are influenced by the essential trace elements occuring in the body. The ingestion of the toxic metals or their salts even in the low concentration 81ters the metabolism of these trace elements (I). Zinc is an antagonist to lead and its protective role in reducing the uptake and metabolic effects of lead are now well recognised (2-4). The changes in the levels of trace elements in the body can be useful for early detection of heavy metal intoxication.
The present
investigation deals with the effects of lead on the distribution of zinc in the body organs bo~eand serum of rats. MATERIALS AND M~THODS Sprague Dawley rats fed on Altromin pellet diet and water ad libitum were used in the study.
They were given 50 mg/kg, Pb as Pb(CH3CO0 ~.
3H20 (E. Merck) dispensed in 4 ml of normal saline intraperitoneally daily for 6 days. the saline.
The control animals received an equal volume of
The body weight was recorded daily and the animals
were killed on 8th day.
Blood was collected from heart for serum
separation and in heparinised polysterolvials for lead determination.
Liver, kidneys, testis and femur bone were collected,
cleaned free of extraneous material and weighed.
1067
1068
The tissues were fridge-dried and weighed amount was digested with nitric acid in Perkin Elmer Autoclave III at 145°C under pressure for 45 minutes.
The digested material was raised to a volume
and further diluted appropriately for the determination of zinc(5), serum, was suitably diluted and used for the estimation of zinc directly in alr-acetylene flame of Perkin-Elmer atomic absorption spectrophotometer
303 by the method of standard addition at 213.9 nm.
For blood lead determination,
50jul of blood was mixed with two
volumes of 5% Triton X-tO0 and three vokumes of deionised water or lead standards corresponding to O.&, 0.8 or 1.2 ng Pb/20 p l in the final volume.
Twenty]ul of the sample was injected into the Perkin
Elmer heated graphite atomizer (HGA 76-B) attached to a Perkin Elmer atomic absorption spectrophotometer 420 and analysed for lead (6) at 283.3 nm using following operating programme : Drying
Ashing
Atomization
Burnout
Time (Sec)
35
30
8
2
Temp.(O°C)
100
600
2250
2500
Bone digest was appropriately diluted and 20 p l was injected into the furnace for the analysis of lead by the method of standards addition using the same programme. RESULTS AND DISCUSSION The levels of lead in blood & bone and
~hose of zinc in liver,
kidney, testis, bone & serum are shown in tables I and 2 respectively.
1069
Table 1: Lead content of blood and bone of rats after daily administration of lead acetate for six days.
C on trol
Experimental
Hlood
3 •57+--0.40 (5)
490.8+-31.89a (5)
Bone
0.149+-0.03 (6)
220.6+-19.74a (6)
Table 2: Zinc content in liver, kidney, testis, bone and serum of ra~ after daily admi~:istration of lead acetate for six days.
Control
Experimental
Liver
124.55+2.10 (6)
152.93+_4.65b (5)
Ki~ey
104.10+2.11 (6)
96.38+--I.57 C5)
Testis
187.16+-2.72 (5)
202.74+4.96 (6)
Bone
202.19+--3.57
178.74+2.8 c
WW
(5) Serl~n
126.9+-4.81 (5)
(5) 78.87+_1.37a (4)
* Aag/dl. *w ~I~/~ dry weizht ~sch value represents the mean + S.E. ap&o.o01, bp&Oo01, COLO.05_ when coz:psred to control as evalu~ted by Students' 't' test.
Io7o
The uptake of lead in bone and blood of the rats treated with lead acetate was significantly increased.
The level of zinc increased
significantly in liver and it remained unaffected in kidneys and testis on trea~tment with lead acetate. However the concentration of zinc in serum and bone decreased significantly upon treatz~ent with lead. The nutritional
status has a profound effect on the response
of an organism towards a dose of poison like lead (7) and the involvement of trace elements in the body organs play an important role in influencing its toxici~'.
Zinc is kno~,rn to have influence
in reducln~ the uptake and metabolic effects of lead such as inhibition of S -aminolevulip~c acid dehydratase in blood(2,4,8,9).
The
diets containing high levels of both lead and zinc when fed to rats have been shown to result in markedly reduced ~ - i n a r y S - A L A
concen-
tration as compared to levels produced by corresponding diets containing high lead alone (10). It has also been found that the orotection provided by zinc against lead toxicit ., i n c r e s s ~ with the level of zinc supplimentatio:,(3).
The present r:sults indicate that there
is an involvement of zinc in the body in influencin~ lead toxicity resultin~ in mobilization of zinc from bones and soran ~hich is at least partially taken ~o by the liver. This would su[~port the view that the antagonistic effects of zinc in lead intoxication is due to its interf:rence in lead absorption and that zinc and lead compete for similar bindlns sites on metallothionein llke proteins.
It has
also been shush that increased zinc intake caused increased renal and hepatic metallothionein lesdinz to detoxi~ication through lead binding in this form (11).
lO71
S~4ARY Effect of lead exposure on the distribution of zinc in the body organs, bone and serum of rats was investigated, to understand the role of zinc against lead exposure.
Zinc content of liver was
increased and that of serum and bone was decreased on exposure to 50 mg/kg Pb as lead acetate intraperitoneally daily for six days. It is possible that lead and zinc compete for binding sites in the liver on some metallothlonein like proteins. A CYdqOWTuEDGF/,~NfS The author is grateful to the German Academic Exchange Service for providing a Scholarship and to the Director, Institute for Pharmacology and Toxicology in Mannheim, University of Heidelberg (FRG) where the work has been done.
Thanks are due to Mr H. Dick
for technical assistance. REFERENCES 1)
Petering, H.G. (1978). Environ. Health Perspect, 25, 141-145.
2)
Cerklewski; F.L. and Forbes, R.M. (1976). J. Nutr. 106,688-~6
3)
E 1 G a z z a r R.M., Finel~; V.N., Boiano J. and Petering, ~.G. (1978). Toxicology Letters ~, 227-234.
4)
Finelli, V.N., Klauder, D.S., ~araffa, M.A. and Petering, H.G. (1975). Clin. Chem. ~ , 30)-51~.
5)
Parker, M.M., Humoller, F.L. and Mahler, D.J.(1967). Clin. Chem. 13, 40-48.
6)
Fernandez, F.J. (1975). Clin. Chem. 21, 558-561.
7)
Levander O.A. (1979), Environ. Hlth. Perspect. 29, 115-125.
1072
8)
Border, E.A., Cantrell, A.C., and Kilore-Smith T.A. (1976). Brit. J. Ind. Med. 33, 85-87.
9)
Haeger-Aronsen, B., Abdulla, M. t and Schutz, A. (1976). Arch. Environ. Health 31, 215-220.
10) Thawley, D.D., Willoughby, R.A., McSherry, B.J., MacLeod, G.K. Maekay, K.H. and Mitchell W.R. (1977) Environ. Res. 14, 463-475. 11) Bremner, I. (~974), O. Eev. Biophys. ~, 75. (Received in Japan 16 July 1981)