Constant light exposure terminates pregnancy in rats with pineal gland dysfunction, low melatonin level and pro-inflammatory response

Abstract

In the current study, the prolonged light exposure at night on the function of pineal gland, melatonin production, pro-inflammatory response and progress of pregnancy in pregnant rats were investigated. A long term (entire gestation stage) of 24 h light exposure not only modify the morphologies of pinealocytes by decreasing their nucleus/cytoplasm ratio and mitochondrial numbers but also reduce the level of circulating melatonin. The biological consequences for this constant light exposure in pregnant rats were the elevated the pro-inflammatory response indicated by the increased production of IL-6 and finally, the termination of pregnancy compared to their controlled counterparts under the normal light/dark cycle. The result showed that the pregnancy was terminated at the early stage of embryo development. The report, for the first time, established a potential association among the pineal function, pro-inflammatory reaction and pregnant progress under the influence of light exposure. This observation has a high relevant to the rise in human infertility since humans have overexposed to the light at night with the increased light pollution globally.