Dietary zinc attenuates renal lead deposition but metallothionein is not directly involved |
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Authors: | Jennifer A Jamieson Danielle M Stringer Peter Zahradka Carla G Taylor |
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Institution: | (1) Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2;(2) Department of Physiology, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2;(3) Institute of Cardiovascular Sciences, St Boniface Research Centre, Winnipeg, MB, Canada, R2H 2A6 |
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Abstract: | Chronic lead exposure irreversibly damages the kidneys and may be associated with hypertension and renal insufficiency at
sub-clinically toxic levels. Zinc supplementation reduces lead absorption and tissue retention in rodent models but the mechanisms
are unknown. Metallothionein (MT) may function in lead detoxification. Our objective was to investigate the effects of marginal
zinc (MZ) and supplemental zinc (SZ) intakes on renal lead and zinc accumulation, renal MT immunolocalization and levels.
Weanling Sprague Dawley rats were assigned to MZ (8 mg Zn/kg diet), zinc-adequate control (CT; 30 mg Zn/kg), zinc-adequate
diet-restricted (DR; 30 mg Zn/kg) or SZ (300 mg Zn/kg) groups, with and without lead acetate-containing drinking water (200 mg Pb/L)
for 3 weeks. Kidneys were analyzed for lead and zinc by inductively coupled plasma spectroscopy and MT by immunolocalization
and Western blotting. MZ had higher renal lead and lower renal zinc concentrations than CT. SZ was more protective than CT
against renal lead accumulation. Renal MT levels reflected dietary intake (SZ ≥ DR ≥ CT ≥ MZ) but lead had no effect on MT
staining intensity, distribution, or relative protein amounts. In summary, while SZ lowered renal lead concentration, MT did
not appear to function in renal lead accumulation. Future studies should explore alternate mechanisms of renal lead detoxification. |
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Keywords: | Kidney Lead Zinc Metallothionein Rat |
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