Tubular stress proteins and nitric oxide synthase expression in rat kidney exposed to mercuric chloride and melatonin.
Stress proteins such as HSP70 members (HSP72 and GRP75) and metallothionein (MT) protect the kidney against oxidative damage and harmful metals, whereas inducible nitric oxide synthase (iNOS) regulates tubular functions. A single dose of mercuric chloride (HgCl(2)) can cause acute renal failure in rats, its main target being the proximal tubule. Oxidative damage has been proposed as one of its pathogenic mechanisms. In this study we tested whether melatonin (MEL), a powerful antioxidant compound, is effective against HgCl(2) nephrotoxicity. Rats were treated with saline, HgCl(2) (3.5 mg/kg), MEL (5 mg/kg), and MEL + HgCl(2) and examined after 24 hr for HSP72, GRP75, MT, and iNOS by immunohistochemistry and immunoblotting. Tubular effects of the treatment were then characterized by ultrastructure. In the HgCl(2) group, all markers were overexpressed in convoluted proximal tubules and sometimes in distal tubules. In the MEL + HgCl(2) group, GRP75 and iNOS decreased in convoluted and straight proximal tubules, whereas HSP72 and MT persisted more than the saline and MEL-only groups. Tubular damage and mitochondrial morphometry were improved by MEL pretreatment. In conclusion, the beneficial effect of MEL against HgCl(2) nephrotoxicity was outlined morphologically and by the reduction of the tubular expression of stress proteins and iNOS. These markers could represent sensitive recovery index against mercury damage.
Stacchiotti
Alessandra
A
Division of Human Anatomy, Department of Biomedical Sciences and Biotechnology, University of Brescia, Viale Europa 11, I-25123 Brescia, Italy. stacchio@med.unibs.it
Ricci
Francesca
F
Rezzani
Rita
R
Li Volti
Giovanni
G
Borsani
Elisa
E
Lavazza
Antonio
A
Bianchi
Rossella
R
Rodella
Luigi Fabrizio
LF
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D050884:HSP72 Heat-Shock Proteins / Q000096:biosynthesis*; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D007684:Kidney Tubules / Q000187:drug effects / Q000648:ultrastructure; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis*; D008627:Mercuric Chloride / Q000633:toxicity*; D008668:Metallothionein / Q000096:biosynthesis*; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000975:Antioxidants; D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; D008565:Membrane Proteins; C018551:glucose-regulated proteins; D008627:Mercuric Chloride; D008668:Metallothionein; D019001:Nitric Oxide Synthase; D008550:Melatonin