Name: JOÃO VICTOR DA SILVA COUTINHO
Publication date: 26/10/2020
Advisor:
Name |
Role |
|---|---|
| SONIA ALVES GOUVEA | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| CARLOS AUGUSTO CARDOSO PASSOS | External Examiner * |
| CARMEM LUIZA SARTORIO | Internal Examiner * |
| JAIRO PINTO DE OLIVEIRA | External Examiner * |
| SONIA ALVES GOUVEA | Advisor * |
Summary: There are many important gaps that need to be addressed regarding the biological effects of low doses of radiation on human health. The radiation protection measures are highly questioned by some authors, and this limit is lower than the radiation value received by residents of places that naturally emit radiation, such as in the city of Guarapari (Brazil). Due to the presence of monazitic sands, Meaípe beach, emits natural gamma radiation that can present peaks ~ 20 μSv.h-1. Thus, the objective of this study was to investigate the effects of low doses of gamma radiation, using a physical simulator (SF) of radiation developed with the monazitic sands of Meaípe on the biological system of adult Wistar rats. For this, the animals were divided into three groups: CON group (they were not exposed to radiation); LR group (exposed to ~3,6 μSv.h-1 radiation) and HR group (exposed to ~20 μSv.h-1 radiation). The three groups of animals were monitored daily for 3 months. The rats were weighed weekly and followed up daily to assess the acute effects of radiation. After 30 days of exposure, the estrous cycle started to be collected daily until the 45th day for the period between 8:00 and 9:00 am. In the penultimate week of the experiment, the animals' systolic blood pressure was assessed. After 90 days of exposure, the animals were sacrificed and the organs were extracted and weighed for anthropometric, histological and biochemical analyzes. Exposure to radiation released by monazitic sands did not cause anthropometric changes in the irradiated animals, nor histomorphometric changes in the ovaries, kidneys and liver. There was no change in the quantification of ovarian follicles, in the estrous cycle or in the concentration of circulating estrogen, indicating that the reproductive function in these animals was preserved. Radiation was also not able to change the blood pressure of the animals and was also not able to increase oxidative stress or circulating protein C levels. In assessing the plasma cytokine concentration, finding an increase in the IL-6 concentration of the animals exposed compared to the control group, while the levels of INF-y, IL-2, IL-4 and IL-10 were lower in the irradiated animals. These changes may be related to the mechanisms of cellular adaptation to low doses of radiation, indicates that this exposure was able to immunologically modulate the irradiated animals and activate the devices related to inflammation even in the absence of tissue damage. Our results show that the continuous exposure of Wistar rats to low doses of natural gamma radiation was able to activate the immune system in a non-specific way even in the absence of tissue damage, this result is probably associated with cellular adaptation and inflammation. In this way, new experiments are corrected to determine more precisely if this radiation can cause harm to human health.
