Preterm birth is a major contributor to early and delayed physical and
cognitive impairment. Epidemiological and experimental data indicate that maternal
infections are a significant and preventable cause of
preterm birth. Recently,
melatonin has been suggested to exert
neuroprotective effects in several models of
brain injury. Here, we sought to investigate whether the administration of
melatonin is able to prevent
lipopolysaccharide (LPS)-induced fetal brain damage in a model of LPS-induced
preterm labor. For this purpose, 15-day pregnant BALB/c mice received intraperitoneally 2 doses of LPS or vehicle: the first one
at 10:00 hours (0.26 mg/kg) and the second at 13:00 hours (0.52 mg/kg). On day 14 of pregnancy, a group of mice was subcutaneously implanted with a pellet of 25 mg
melatonin. This experimental protocol resulted in 100% of
preterm birth and pup death in the LPS group and a 50% of term birth and pup survival in the melatonin + LPS group. In the absence of
melatonin, fetuses from LPS-treated mothers showed histological signs of brain damage, microglial/macrophage activation, and higher levels of IL-1β,
inducible nitric oxide synthase (NOS), and neuronal NOS mRNAs as well as increased
histone acetyltransferase activity and
histone H3 hyperacetylation. In contrast, antenatal administration of
melatonin prevented LPS-induced fetal brain damage. Moreover, when behavioral traits were analyzed in the offspring from control,
melatonin, and melatonin + LPS, no significant differences were found, suggesting that
melatonin prevented LPS-induced long-term neurodevelopmental impairments. Collectively, our results suggest that
melatonin could be a new therapeutic tool to prevent fetal brain damage and its long-term consequences induced by maternal
inflammation.