ESPE Abstracts

Purpose: Our study aimed to examine the effects of blue light exposure on prepubertal male rats’ puberty and testis tissue.

Methods: Eighteen 21-day-old male Sprague Dawley rats were divided into three groups consisting of six rats in each group: Control Group (CG), Blue Light-6 hours (BL-6), and Blue Light-12 hours (BL-12). CG rats were maintained with 12/12-hour light-dark cycles. The rats of BL-6 and BL-12 were exposed to blue light (450–470nm, irradiance level 0.03uW/cm2) for 6 hours and 12 hours, respectively. Rats were exposed to blue light until the first signs of puberty. The ELISA method was used to analyze the serum concentrations of FSH, LH, testosterone, DHEA-S, leptin, ghrelin, melatonin, glutathione, glutathione peroxidase, and malondialdehyde. Testes were dissected for histomorphological examination.

Results: The medians of the pubertal entry days of the CG, BL-6, and BL-12 were 38, 30, and 28 days, respectively (p: 0.001). The age of onset of puberty decreased as the duration of blue light exposure increased (r: -0.97, P<0.001). Weight gain (%) was similar between the groups (P>0.05). Leptin concentrations were lower in BL-12 compared to BL-6 (p: 0.003). There was no correlation between weight gain (%) and leptin (P>0.05), although serum leptin concentrations decreased as the onset of puberty progressed earlier (r: 0.53, p: 0.02). Ghrelin concentrations in the groups were similar (P>0.05). The FSH, LH, and testosterone concentrations of all groups were similar (P>0.05). The FSH concentration increased as the LH concentration increased (r: 0.82, p: 0.001). The LH concentration increased as serum testosterone, and DHEAS decreased, respectively (r:-0.56, p:0.01),(r:-0.55 p:0.01). Testicular lengths and weights of the BL groups were smaller compared to CG (P=0.03),(P=0.04). GPx was higher for BL-6 and BL-12 than the CG (p:0.02, p:0.02). Testis tissue was compatible with the pubertal period in all groups. As the blue light exposure time increased, spermatogenesis was suppressed, and capillary dilatation and edema in the testis tissue increased.

Conclusion: In our study, exposure to blue light accelerated the onset of puberty in male rats. When the length of exposure to blue light increased, the onset of puberty occurred earlier. To the best of our knowledge, this study is the first to demonstrate the effects of blue light exposure on male rats' puberty onset. The blue light exposure suppressed spermatogenesis, marked vasodilatation in the interstitial area of the testis, and disrupted the integrity of the basement membrane. These findings intensified with increasing exposure time.