Exposure to Methylmercury

Overview

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Key numbers

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cern (1, 2). Mercury occurs naturally in the environment on tion by low daily doses, in which about 90% of Hg is present
salivary glands, representing about 90% of the total salivary generator, the 2,2′-azobis 2 methylpropionamidine dihy-
food ad libitum. Corn oil or MeHg with a daily dose of (0.1% N-(1-naphthyl) ethylenediaminedihydrochloride; 1%
0.04 mg/kg was orally administered by gavage over a period sulfanilamide in 5% phosphoric acid; 1 : 1) proceeding the
2.4. Oxidative Biochemistry Analysis. The samples were 2 M thiourea, 0.5% CHAPS, 0.5% IPG buﬀer pH 3–10,
ﬁrst thawed and homogenized in 700 μL Tris-HCl buﬀer 18 mM DTT, and 0.002% bromophenol blue). Twenty-ﬁve
Figure 1: (a) Eﬀects of MeHg chronic exposure at a dose of 0.04 mg/kg/day during 60 days on body mass gain of rats. The results are
expressed as mean ± SEM (n = 20 animals per group) with one-way ANOVA with repeated measures followed by Tukey test. (b) Total
mercury deposits on salivary glands of rats exposed to MeHg for 60 days. The values are expressed as mean ± SEM of Hg concentrations.
was added. In sequence, 25 μL of 0.2% RapiGEST™ (Waters
and digestion occurred for 14 h at 37°C. After digestion, respectively, as percentage of control and mean ± SEM. All
10 μl of 5% TFA was added, incubated for 90 min at data were compared using Student’s t-test with a level of
(1 pmol/μL) plus 85 μL 3% ACN was added. 3. Results
matics analysis was performed using Uniprot protein ID (ppm) on salivary glands (Figure 1(b)). Our results showed,
36.92% ± 14.51 more RNS than in control group, whereas lated on submandibular glands (Table 2); and 7 proteins
sublingual (Figure 2(b)) showed 58.24% ± 12.26 and parotid downregulated and 2 upregulated on sublingual glands
(Figure 2(a)) 59.67% ± 7.32 more than control, respectively. (Table 3). The proteomic analysis of the three salivary glands
(Figure 3(a)) showing 86.89% ± 15.71 more RNS than in con- In parotid gland, MeHg was able to change 20 catego-
56.42% ± 11.65 and sublingual (Figure 3(c)) 50.45% ± 8.09 (Figure 5(a)). Our data showed that they are related to
more than the control, respectively. the following biological processes: nucleosome (20.31%),
We further showed that MeHg is able to induce lipid per- aerobic respiration process (7.81%), NAD binding
oxidation, by the yields of MDA (Figure 4), on salivary glands (7.81%), mesenchyme migration (6.65%), hydrolyase activ-
of MeHg group. The results showed higher levels of MDA in ity (6.25%), oxygen binding (4.69%), and response to
all three major glands. All glands of MeHg group showed mercury ion (4.69%). Regulation of cellular respiration,
100% more damaged than those of the control animals. The protein transmembrane transport, melanosome, nucleoso-
parotid (Figure 4(a)) showed about 121.16% ± 18.2 higher, mal DNA binding, retina homeostasis, benzaldehyde
submandibular (Figure 4(b)) about 141.94% ± 27.18 higher, dehydrogenase (NAD+) activity, myelin sheath, intermedi-
and sublingual (Figure 4(c)) about 106.59% ± 29.38 more ate ﬁlament, pigment granule, mRNA 5′-UTR biding, cel-
3.13% each. synthase complex, catalytic core F (1), phosphoserine bind-
to 31.43%; the structural constituent of cytoskeleton and the (Figure 6(b)).
substance nigra development represent 11.43%, each. More- Sublingual glands presented the lower number of protein
symbolizes 8.57% of the proteins with alterations. Adenylate is represented by myelin sheath (33.33%), unfolded protein
binding (19.05%), retina homeostasis (14.29%), structural after MeHg exposure brings the association with diﬀerences
constituent of cytoskeleton (14.29%), detection of chemical in expression at important proteins of metabolic pathways,
(9.52%), and alpha-amylase activity (9.52%). cytoarchitecture.
and cytoskeletal rearrangements. In addition, proteins asso- vascular diseases and genotoxicity (24–27). This latter one
cological evaluation on the proteomic proﬁle of rat glands as paresthesia is 50 ppm of mercury in hair (28). This
Table 1: Identiﬁed proteins with expression signiﬁcantly altered in rat parotid glands of group exposed to Mehg (Hg).
level in hair corresponds approximately to 1 ppm of such as alterations of forelimb grip strength, running wheel
used in our work (0.04 mg/kg per day for 8 weeks) is about a glands accumulated about 10 times less mercury than
half of that level, that is, about 0.5 ppm (17, 30), characteriz- 0.5 ppm. However, our results show for the ﬁrst time that this
Table 2: Identiﬁed proteins with expression signiﬁcantly altered in rats’ submandibular glands of group exposed to Mehg (Hg).

Methods (brief)

collected for evaluation of total mercury levels, proteomic proﬁle, and oxidative balance by analyzing the antioxidant capacity
quences of this metal exposure. Amado et al. (19). The supernatant of each sample after cen-
2.1. Animals and Experimental Groups. A total of 40 male sample had low capacity to neutralize the peroxyl radicals.
2.2. Samples Collection. After 24 hours of the last administra- An aliquot of the supernatant was processed as described
ular, and sublingual) collected and frozen in liquid nitrogen The absorbance measurement on spectrophotometers was
2.3. Mercury Deposits. Total mercury content in the samples
was quantiﬁed by wet digestion, reduction, and cold vapor 2.5. Proteomic. The frozen salivary glands were homogenized
atomic absorption spectrometry with gold amalgamation in a cryogenic mill (model 6770, Spex, Metuchen, NJ, EUA).
system Mercury Analyzer: SP3D (Nippon Corporation). For protein extraction, gland homogenate was incubated in
sample of groups, and the values were tabulated to further itated using the kit PlusOne 2D Cleanup (GE Healthcare,
2.4. Oxidative Biochemistry Analysis. The samples were 2 M thiourea, 0.5% CHAPS, 0.5% IPG buﬀer pH 3–10,
3 M urea was added. Each sample was ﬁltered twice in 3 kDa codes “All,” set networking speciﬁcity “medium” (GO levels
content was measured in the pooled samples by Bradford interaction (ppi) network was built by ClusterMarker,
protein assay (23). To each sample (50 μg of total protein another Cytoscape plugin. After the network creation, we
Mass Spectrometry, Promega, Madison, USA) was added 5.0 software (San Diego, CA, USA) and were expressed,
and digestion occurred for 14 h at 37°C. After digestion, respectively, as percentage of control and mean ± SEM. All
37°C, and the sample was centrifuged (14,000 rpm for signiﬁcance of p < 0 05.
30 min). The supernatant was collected, and 5 μL of ADH

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised