@conference{
author = "Miler, Marko and Živanović, Jasmina and Ajdžanović, Vladimir and Šošić-Jurjević, Branka and Marković, Zorica and Milošević, Verica",
year = "2020",
abstract = "Citrus flavanone naringenin (NAR) is a potent antioxidant with ability to
change pituitary-thyroid function. NAR increases concentration of thyroid-
stimulating hormone (TSH) in serum by increasing Sirtuin1 expression
in the pituitary thyrotrophs and improves thyroid hormonogenesis capacity
in old-aged rats. Thyroid hormone production is followed by generation of
large quantities of reactive oxygen species (ROS) which are essential for
iodine organification. A master regulator of redox status, NRF2 protein,
together with antioxidant enzymes (AOE), is responsible for maintenance
of redox/antioxidant balance in the cell. Considering that NRF2 expression
can be affected by NAR, besides TSH, the study aim is to analyze gene and
protein expressions of NRF2 and AOE in the thyroids of 24-month-old male
Wistar rats. NAR was suspended in sunflower oil (vehicle) and administrated
directly to the oral cavity, at a dose of 15 mg/kg b.m., during 4 weeks.
Control group received vehicle only. We performed qPCR and immunoblot
analyses for gene and protein expressions, respectively. Obtained results
showed that NAR treatment lowered (P < 0.05) mRNA levels of Nrf2, superoxide
dismutase 1 and 2 (Sod1, Sod2) and catalase (Cat) for 42%, 32%, 45%
and 35%, respectively, while it only increased (P < 0.05) expression of glutathione
peroxidase (Gpx) for 54%, all in comparison with the controls. Gene
expression of glutathione reductase (Gr) remained unchanged. Also, NAR
up-regulated (P < 0.05) protein expression of NRF2 and SOD2 for 58% and
50%, respectively, and down-regulated (P < 0.05) SOD1 expression for 48%,
all when compared to the adequate control values. CAT, GR and GPx protein
expressions didn’t change after NAR treatment. It can be concluded that
NAR changes gene and protein expression of NRF2 in old-aged rat model.
Down-regulation in Nrf2 gene expression, and some AOE, is in line with
previously observed TSH stimulation after NAR. Antioxidant protection in
thyroid needs to be lowered in order to ensure sufficient ROS for adequate
thyroid hormones production. However, due to NAR prooxidant properties,
redox status in thyroid upon its application was changed, inducing accumulation
of NRF2 protein in the thyrocytes. This led to increment of Gpx
gene and SOD2 protein expression, helping in maintenance of fundamental
antioxidant protection and disposal of excessive ROS in the thyroid gland
of old-aged rats.",
publisher = "European Society of Endocrinology",
journal = "22nd European Congress of Endocrinology; 2020 Sep 5-9",
title = "The effects of naringenin on NRF2 and antioxidant enzymes expressions in the thyroids of the old-aged Wistar rats",
doi = "10.1530/endoabs.70.AEP919",
pages = "372"
}
