Assessment of reproductive hormones in prepubertal and postpubertal rats (Rattus norvegicus) on chronic exposure to various spectra of artificial light at night

Exposures to Artificial Light at Night (ALAN) is on the increase with resultant varied physiological impact related to the light spectrum via the non-visual pathway. This study examined the effects of various spectra of ALAN on Testosterone (Te), Progesterone (Pr) and Estradiol (Es) in rats exposed to Blue (BL), Green (GL), Yellow (YL), Red (RL), White (WL) and Darkness (DD) light wave-lengths while Ambient light (CL) served as the control. Dams with their post-natal day 1 pups were housed in cages exposed to various light wavelengths for 12 hours: (6:00pm–6:00am) daily for 126 days. At d63 and d126, five rats per treatments were euthanized; blood serum was collected and the serum hormones: Te, Es and Pr were analysed using ELISA. The results showed that light treatments had significant effect on the level of Te at d63 but not at d126 in male rats. At d63, onset of puberty, Te was significantly highest (p < 0.05) under BL. In females exposed to YL and WL at d126, Te was significant high and Es was significantly low. Estradiol was heightened significantly (p < 0.05) in both sexes exposed to RL. In conclusion, BL seemed to stimulate early sexual development in males, WL and GL enhanced post-pubertal male albino rat reproductive system while RL provided the best reproductive environment for females in the long term. Long periods of exposure to YL seemed to pose risks for male and female reproductive function.