ABSTRACT
Introduction: In the last 10 years, blue light (BL) sources such as tablets and phones has increased in every age group. Especially due to the Covid-19 pandemic, screen exposure has also increased in childhood. However, the effects of BL exposure in the puberty process aren't clear. We aimed to examine the effect of BL exposure and exposure time on puberty Methods: Immature eighteen 21-day-old female Sprague Dawley rats were divided into three groups consisting of six rats in each group: Control Group (CG), Experiment Group-1 (EG-1), Experiment Group-2 (EG-2). CG rats were maintained under standard conditions with 12/12-hour light-dark cycles. The rats of EG-1 and EG-2 were exposed to BL (450-470 nm / irradiance level 0.03 uW/cm2) for 6 hours and 12 hours, respectively. Rats were exposed to BL until the first signs of puberty and then they were euthanasiad. Serum FSH, LH, Estrodiol, testosterone, DHEA-S, leptin, melatonin were studied by ELISA method. Ovaries and uterus were dissected for histomorphological examination Results: The medians of the pubertal entry days of the CG, EG-1 and EG-2 were 38th, 32th, and 30th days, respectively. (p: 0.001) A negative correlation was found between the puberty entry day of the groups and the exposure to BL and the duration of exposure. (r:-0.910, p<0.001) The FSH, testosterone, DHEA-S, leptin levels of all groups were similar. (p> 0.05) However, LH and estradiol levels of EG-1 were higher compared CG. (p:0.027) There was a negative correlation between BL exposure, exposure time and melatonin levels (ro:- 0.537, p: 0.048) Ovarian tissue was compatible with pubertal period in all groups. As the BL exposure time increased, capillary dilatation and edema in the over tissue increased. Prolonged exposure caused polycystic over like (PCO-like) morphological changes and apoptosis in granulosa cells. Conclusion(s): Our study is the first to show the effects of BL exposure on puberty. In our study, we showed that exposure of BL and the duration of exposure lead to early puberty. PCO-like, inflammation and apoptosis were detected in the ovaries with the increase in BL exposure time. There are studies showing that there is an increase in cases with precocious puberty and acceleration in puberty pace during the closure period compared to the pre-pandemic period. In our study, we experimentally demonstrated the effects of BL exposure on puberty and the relationship between increased exposure time.