The role of caffeine and probiotics in modulating biochemical alterations induced by constant light-mediated circadian rhythm disruption in a rat model

Light pollution has become a potential health risk factor worldwide. It exerts its effect by disrupting the circadian rhythms, which is linked to adverse health outcomes, including mood disturbances. Caffeine can influence alertness and sleep patterns, while probiotics may affect circadian regulation through the gut-brain axis. Consequently, this study aimed to investigate the potential role of caffeine (30 mg/kg) and probiotics (1 billion colony forming units (CFUs) per day) in alleviating biochemical alterations associated with depression following constant light exposure. Neurotransmitters, glutathione (GSH), malondialdehyde (MDA), and melatonin (MEL) were estimated in the cerebral cortex and the hypothalamus. Hormonal levels of MEL and corticosterone (CORT) were measured in serum samples. LL exposure reduced serotonin (5-HT) levels. It also induced alteration in MEL and CORT rhythmicity. However, caffeine enhanced 5-HT and MEL content and modulated the temporal profile of MEL. Probiotics restored corticosterone and melatonin level to a temporal pattern like controls. Additionally, both treatments reduced MDA levels and enhanced GSH content. Coadministration of caffeine and probiotics reduced 5-HT levels. In conclusion, caffeine and probiotics could modulate biochemical alterations caused by constant light exposure, which is known to disrupt circadian rhythm in rodents, making them apropriate antidepressants.