Clin Exp Otorhinolaryngol.  2017 Dec;10(4):357-362. 10.21053/ceo.2016.01095.

Age-Related Changes in Nuclear Factor Erythroid 2-Related Factor 2 and Reactive Oxygen Species and Mitochondrial Structure in the Tongues of Fischer 344 Rats

• Baek MK
• Lee H
• Kim KO
• Kwon HJ
• Chung MH
• Park HM
• Woo JH
• Kim DY

• KMID: 2396792
• DOI: http://doi.org/10.21053/ceo.2016.01095

Abstract

OBJECTIVES
Previously the authors reported age-related changes in the activities of anti-oxidative enzyme activities and protein expressions in the tongues of rats. Because more information is required about relations between aging and oxidative stress and anti-oxidative enzyme efficiency, the authors investigated differences between the expression of master regulator of anti-oxidative enzymes (nuclear factor erythroid 2-related factor 2 [Nrf2]), levels of reactive oxygen species (ROS), and mitochondrial structures in the tongues of young and aged Fischer 344 rats.
METHODS
Age-dependent changes in Nrf2 protein and ROS were determined by Western blotting and using chemical kits, respectively. Tongue specimens were examined by electron microscopy. The study was conducted using rats aged 7 months (young, n=8) or 22 months (old, n=8).
RESULTS
Nrf2 protein levels in the tongues of aged rats were lower than in young rats. ROS levels were higher in older rats and mitochondrial structural deficits were observed their tongues. Three young rats showed moderate mitochondrial degeneration, whereas profound degeneration with mitochondrial cristae disruption, swelling, rupture, or intramitochondrial vacuole formation was observed in all 8 old rats. Notably, mitochondrial rupture was observed in 5 old rats.
CONCLUSION
Antioxidant defense systems of old rats were compromised by Nrf2 deficiency, which could lead to the deleterious accumulation and release of ROS and probably mitochondrial structural deficits in aged tongue tissues.

Keyword

Tongue; Aging; NF-E2-Related Factor 2; Reactive Oxygen Species; Mitochondria

MeSH Terms

Aging
Animals
Blotting, Western
Microscopy, Electron
Mitochondria
NF-E2-Related Factor 2
Oxidative Stress
Rats*
Reactive Oxygen Species*
Rupture
Tongue*
Vacuoles
NF-E2-Related Factor 2
Reactive Oxygen Species

Figure

• 

  Fig. 1. Western blot analysis of nuclear factor erythroid 2-related factor 2 (Nrf2) protein expressions in the tongues of young (7 months) rats (n=8) and old (22 months) rats (n=8). Protein (50 μg) lysates from tongue homogenates of young and old rats were resolved by SDS-PAGE (National Diagnostics) and probed with Nrf2 antibodies. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as a loading control. (A) Western blot image of tongue samples. (B) Relative Nrf2 protein expressions were normalizing versus GAPDH. Results are expressed as median values. *P<0.05 vs. young rats by the Mann-Whitney U-test.

• 

  Fig. 2. Reactive oxygen species (ROS) levels in the tongue tissues of young (7 months) and old (22 months) (n=8 animals/group). Results are expressed as median values, *P<0.05 vs. young rats by the Mann-Whitney U-test. DCF, 2´,7´-dichlorodihydrofluorescein.

• 

  Fig. 3. Transmission electron microscopy image of mitochondrial structures in young (7 months) rats (Reynold’s stain, ×30,000). (A) Mitochondria were normal and mitochondrial cristae were well preserved (arrow). (B) However, some mitochondrial cristae disruption and swelling (arrowhead) were observed.

• 

  Fig. 4. Transmission electron microscope image showing mitochondrial structure in old (22 months) rats (Reynold’s stain, ×50,000). (A) Profound degeneration was evidence by mitochondrial cristae loss, swelling (arrow), and vacuole formation (arrowhead). (B) Mitochondria showed cristae loss, vacuole formation, and membranous rupture (asterisk).

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