@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2016;22(3):221-227

Background
... [1-2]. Disorders in serum level of thyroid hormones can cause several disruptions [3].
Previous Studies
... [4-6] the amount of entry of chemical substances into the body and how the person is exposed to them are among the most important issues on the effect of chemicals on humans. Chemicals can enter the human body in different ways, such as various ways of breathing (entering through respiratory tract), gastrointestinal (entering through the digestive tract) and skin contact. Except for corrosive substances (acids and bases), toxic substances do not usually have harmful effects on the body in the beginning, but they can be a part of physiological processes of the human body including absorption, distribution and storage, transfer and removal. For toxicity, it is essential for the chemical or products resulting from their biological transfers to reach critical areas of the body in a certain time and concentration (particular organs in the body) [7]. ... [8-9].
Aim(s)
The study aimed to investigate the effects of inhaling oil paints fumes on serum levels of thyroid hormones in male and female rats.
Research type
This is an experimental study which is carried out in laboratory.
Research society, place and time
This experimental study was performed in 2014 at the Islamic Azad University of Hamedan.
Sampling method and number
15 male rats and 15 female Wistar rats with the weight range of 200 to 250 grams were bought from Pasteur Institute. The rats were kept at approximately 22 ± 2° C and in 12-hour period of light and darkness (12 hours of darkness and 12 hours of light) considering the beginning of photoperiod at 8 am. Water and food (food prepared specifically for rats by Dam Pars factory; Iran) was available unlimitedly. Clinical studies were frequently performed to detect the common symptoms of pathology.
Used devices&materials
The animals were randomly divided into 6 groups of 5; two male and female control groups that did not inhale any substance during the experiment, and four one and eight-hour groups of male and female rats which were exposed to the smell of oil paint during the experimental period on a daily basis for one and eight hours, respectively, and inhaled the smell of oil paint. To keep the mice, special aquarium- like glass cages were prepared and the top of the cages were covered with metal meshes and a perforated plate. The interior surface of the cages was covered with straw because the contamination of the rats` inhaled air is more likely due to the sawdust contaminated with microscopic creatures. In order to place the oil paint, glass grids were created in the cage to put the test tube inside it. 133 ml of white oil paint was daily poured into each cylinder (Howie luxury; Iran) which was purchased from paint shop. Because the oil paint loses its main components by storage due to immediate evaporation, the top of the cages were covered with a cloth made of burlap in order to prevent the air from being exchanged inside the cages. In addition, for more precision, the control group was kept in a separate room. After 10 weeks of inhaling the smell of the paint, blood samples were taken in order to measure the intended factors. Animals` blood samples were obtained from 9 am to 12 pm. In order to observe the protocol of animals` rights protection, the method of open heart blood-taking was chosen for rats from among different sampling methods because in this way, first the animal is anesthetized by ether and the blood sample is taken during anesthesia and the animal does not feel any pain. For anaesthetizing, first the rat was placed in a beaker containing cotton soaked in ether and thus it was anesthetized mildly. In this regard, Verburg et al. have shown that this degree of anesthesia does not specifically alter the levels of hormones [10]. After anaesthetizing, the animal was put on the desk backwards, so that the tail is towards the operator. Then the skin of the chest was removed, the chest was split open using scalpel and scissors and the tip of the syringe was quickly entered to the heart's left ventricle from its head. 30 minutes after blood-taking, samples were centrifuged at 3000 rpm for 10 minutes; the serum was isolated and used for measuring the factors. For data analysis, SPSS 20 software package was used. To determine the normality of data distribution, Kolmogorov-Smirnov test was employed. The analyzed data was all normal. The applied statistical test was two-way ANOVA and Tukey test was used to analyze the differences between two groups. The results were presented as mean.
Findings by Text
The mean of triiodothyronine hormone`s serum level (T3) had a significant reduction in both sexes compared to the control group (p<0.001), so that the process declined more rapidly through increasing the duration of inhaling fumes of the paint, and the serum level mean of T3 hormone revealed a significant decrease in eight-hour group compared to one-hour group in males (p<0.001) and females (p<0.05). The decreasing process was more tangible in females than in males, such that there was a significant difference between the two sexes in one-hour (p<0.001) and eight-hour inhalation groups (p<0.05) (Figure 1). Serum level mean of thyroxine hormone (T4) had a significant reduction in the studied groups compared to the control group (p<0.001) and the more the duration of being exposed to paint fumes increased, the more the decrease in males (p<0.001) and females (p<0.01) was. The decreasing process was more in females than in males and this difference was significant only in one-hour inhalation group (p<0.001; Figure 2). The serum level mean of thyroid-stimulating hormone (TSH) increased through boosting the hours of inhaling paint fumes leading to significant changes compared to the control group (p<0.001). On the other hand, this increasing process was more in female rats and this increase was significant in the group inhaling the paint for 8 hours compared to the male group (p<0.01; Figure 3).
Main comparison to the similar studies
... [10-13] .The lead increases the activity of monoamine oxidase and acetylcholinesterase. These results suggest that lead damages the normal activity of the brain neurotransmitters [14]. ... [15-17]. Heavy metals and paint solvent existing in the oil paint fumes can cause oxidative stress in the cells of the thyroid gland, such that these compounds reduce the amount of thyroid hormones through lipid peroxidation of thyroid gland cells as well as disrupting the function of these cells, and make trouble for the function of this gland [18] ... [19-23].
Suggestions
Future cellular and molecular studies, particularly in the field of the mechanism of oil paint fumes` effects on serum levels changes of thyroxine and triiodothyronine is a favorable research to achieve the mechanism of the impact of oil paint fumes on the performance of thyroid hormones` serum level.
Limitations
This research has limitations regarding the levels of molecular and cellular studies.
Conclusions
Inhaling the fumes of oil paint decreases the function of thyroid gland and the serum levels of T3 and T4 thyroid hormones while it increases the serum level of TSH and this effect is greater in females.
Acknowledgments
This study has been supported by research deputy of Islamic Azad University of Hamedan. Many regards are addressed to their efforts.
Conflict of interest
Non-declared
Ethical Permissions
This study has observed the protocol of animals’ rights protection.
Funding Sources
This research has been financially supported by the research deputy of Islamic Azad University of Hamadan.

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