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.