Methylmercury Intoxication Promotes Metallothionein Response and Cell Damage in Salivary Glands of Rats
Environmental and occupational mercury exposure is considered a major public health issue. Despite being well known that MeHg exposure causes adverse effects in several physiologic functions, MeHg effects on salivary glands still not completely elucidated. Here, we investigated the cellular MeHg-induced damage in the three major salivary glands (parotid, submandibular, and sublingual) of adult rats after chronic, systemic and low doses of MeHg exposure. Rats were exposed by 0.04 mg/kg/day over 60 days. After that, animals were euthanized and all three glands were collected. We evaluated total Hg accumulation, metallothionein I/II (MT I/II), α-smooth muscle actin (α-SMA), and cytokeratin 18 (CK18) immune expression. Our results have showed that MeHg is able to disrupt gland tissue and to induce a protective mechanism by MT I/II expression. We also showed that cell MT production is not enough to protect gland tissue against cellular structural damage seen by reducing marking of cytoskeletal proteins as CK18 and α-SMA. Our data suggest that chronic MeHg exposure in low-daily doses is able to induce cellular damage in rat salivary glands.
KeywordsMeHg Mercury Salivary gland Metallothionein Intoxication
This work was supported by the Brazilian National Council for Scientific and Technological Development (CNPq), Fundação de Amparo a Pesquisa do Estado do Pará (FAPESPA), and Pró-Reitoria de Pesquisa e Pós-Graduação da UFPA (PROPESP, UFPA, Brazil). Leidiane A. O. Lima is a scholar supported by UFPA. Rafael R. Lima is an investigator from CNPq (Edital MCTI/CNPQ/Universal 14/2014).
Compliance with Ethical Standards
All procedures were previously approved by Ethics committee on animal experimentation by Federal University of Para (BIO 225-14 - CEPAE-UFPA) following the guidelines suggested by NIH Guide to Care and Use of Laboratory Animals.
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