1. Introduction
Radiation being an environmental toxicant from several sources is always
present around all living things on earth. Irradiation of the entire
body damages cellular, physiological, and biochemical reactions within
living cells. Radiation effects are influenced by various factors,
including age, gender, exposure time, and affected tissue. These
radiations are emitted and transmitted by various sources and are
absorbed by the animal body. UV rays are non-ionizing rays ranging from
200nm to 400nm. UV radiations are found in sunlight and have enough
energy to easily penetrate body cells, causing changes in chemical and
biological activities. UVB radiation has a wide range of effects on all
living things on Earth, including the infliction of
cancer.1 The amount of ozone in the stratosphere
determines the amount of UVB radiation that reaches the Earth’s surface.
Animals and humans may be harmed by biological reactions to changes in
UVB radiation. The United Nations has conducted regular assessments of
the effects of UVB radiation on people and the
environment.2
Furthermore, radiations have been discovered to be possible endocrine
disruptors. This has been proven to have a deleterious influence on
human and animal reproductive, immunological, and hormone
systems.3 Environmental factors may be playing a role
in the rise in thyroid cancer cases. Chemicals having
endocrine-disrupting effects, in particular, have sparked interest as
possible danger factors.
Thyroid gland and its hormones have essential biological functions in
children as well as adults. They possess essential role in growth and
development especially for brain. In adults, the gland hormones are
involved in the regulation of protein, carbohydrates and lipid metabolic
processes. Moreover, they are essential in regulating heart rate,
reproductive functions, emotional steadiness and gastrointestinal
functions.4,5 Thyroid hormones regulate metabolic and
energy homeostasis, thermogenesis, and the transcription of genes that
control cell proliferation and basal metabolic rate to control an
organism’s growth throughout.6
Flavonoids are diphenyl propanoids that occur naturally in plant foods
such as fruits, grains, and nuts.7 Naringin, the main
flavonoid of grapefruit and nearly only found in citrus fruits, is one
of the most common flavonoids in the diet. The average human dietary
intake of these three flavonoids is unknown, but polyphenol intake is
reported to be nearly 1 g/day, with two-thirds flavonoids such as
naringin. According to epidemiological studies, flavonoids have
biological activities such as antiallergy, antiviral, anti-inflammatory,
antioxidative, and vasodilating properties. An extensive range of
pharmacological and therapeutic properties, including lipid-lowering,
anti-inflammatory, free radical-scavenging/antioxidative,
antihyperlipidemic, anti-apoptotic, and anti-atherogenic properties,
have been reported for naringin (NG), the compound that gives fruits
their sour flavour and bitter taste.8,9
Despite these reported beneficial effects of flavonoids, in vivo studies
are negligible.10 The other two reported
investigations are based on in vitro studies, which very often do not
comply with the in vivo results.11 There is not a
single report on the effect of Naringin on male Swiss albino mice
exposed to UVB irradiation. Furthermore, radiations were used for the
first time to demonstrate the direct free radical scavenging potential
of this flavonoid in thyroid tissue. The present study is the novel
approach to elucidate UVB radiations induced hyperthyroidism by the
treatment of Naringin in male mice.