Sodium Fluoride Disturbs DNA Methylation of NNAT
and Declines Oocyte Quality by Impairing Glucose
Transport in Porcine Oocytes
and Yi-Liang Miao
Institute of Stem Cell and Regenerative Biology, College of Animal Science
and Technology & College of Veterinary Medicine, Huazhong Agricultural
University, Wuhan, Hubei 430070, China
Reproductive Medicine Centre, Afﬁliated Hospital of Qingdao Medical Univer-
sity, Yuhuangding Hospital of Yantai, Yantai, Shandong, China
Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction
(Huazhong Agricultural University), Ministry of Education, Wuhan, Hubei
The Cooperative Innovation Center for Sustainable Pig Production, Wuhan,
Hubei 430070, China
Sodium fluoride (NaF) is used as a medicine to
prevent tooth decay; however, excessive NaF
could cause a pathological damage to the
health. Recent studies showed that NaF
impaired mouse oocyte maturation, included of
abnormal spindle configuration, actin cap for-
mation, cortical granule-free domain formation,
and the following development after fertilization.
However, few studies used large animals as
models to study the toxicology of NaF on
oocytes maturation. We proposed a hypothesis
that NaF would affect the nuclear and cytoplas-
mic maturation of porcine oocytes and DNA
methylation pattern of imprinted genes in
oocytes. Our results showed that NaF affected
cumulus expansion, polar body emission, spindle
morphology, cortical granule distribution, early
apoptosis, and the following development after
parthenogenetic activation during porcine oocyte
maturation. Moreover, NaF increased the DNA
methylation of NNAT and decreased its expres-
sion, which disturbed the glucose transport in
oocytes. These results suggest that NaF impairs
the porcine oocytes maturation epigenetically,
which provides a new toxicological mechanism of
NaF on the oocyte maturation.
Environ. Mol. Muta-
gen. 59:223–233, 2018.
2017 Wiley Periodicals, Inc.
Key words: methylation; NNAT; oocyte; pig; sodium fluoride
Sodium ﬂuoride (NaF) is used to prevent tooth decay
in human in the areas where the drinking water lacks
ﬂuoride. Dental products such as toothpaste and mouth-
wash contain high concentration of ﬂuoride. Mouth rinses
marketed for daily use usually contain between 230 and
500 mg/L ﬂuoride, whereas mouthwash products for
weekly or biweekly use may contain 900–1000 mg/L
ﬂuoride. However, it became to be an industrial pollutant
and was scattered in the environment with the develop-
ment of industrial processes. Excessive NaF caused much
pathological damage to liver, brain, reproductive tissues,
and so on (Zhan et al., 2006; Gupta et al., 2007; Ge
et al., 2011). Moreover, NaF crossed both blood-testis
Grant sponsor: National Key Research and Development Program of
China, Stem Cell and Translational Research; Grant number:
Grant sponsor: The Recruitment Program for Young Professionals” of
“The Thousand Talents Plan”; Grant numbers: 159905 and 169903.
Grant sponsor: Starting Fund for New Recruitment of Huazhong
Agricultural University; Grant number: 14009.
Xiaoyan Liu and Zheng-Wen Nie contributed equally to this work.
*Correspondence to: Yi-Liang Miao, 1 Shizishan St, Hongshan District,
Wuhan, Hubei Province 430070, China. E-mail: email@example.com
Received 19 September 2017; provisionally accepted 6 November 2017;
and in ﬁnal form 5 December 2017
Published online 29 December 2017 in
Wiley Online Library (wileyonlinelibrary.com).
2017 Wiley Periodicals, Inc.
Environmental and Molecular Mutagenesis 59:223^233 (2018)