The protective effects and mechanisms of melatonin on white matter damage in neonatal rats / 中国新生儿科杂志

ABSTRACT

Objective:To study the protective effects and mechanisms of melatonin (MTn) on lipopolysaccharide (LPS) and hypoxic-ischemic(HI) induced white matter damage (WMD) in neonatal rats.Methods:Seventy-two 3-day-old newborn Sprague-Dawley (SD) rats were randomly assigned into sham operation group (the sham group), model group (the HI group) and MTn intervention group (the HI+MTn group) ( n=24 for each group). For the sham group, only dissection of the right common carotid artery was performed without ligation. Animal models of WMD were established using LPS pretreatment and HI method in both the HI group and HI+MTn group. The HI+MTn group received MTn intraperitoneal injection (15 mg/kg, 1 h before LPS injection and then once daily). The HI group and the sham group received equal volume of normal saline containing 1% ethanol intraperitoneal injection. The rats were sacrificed on d7 of experiment and periventricular white matter (PVWM) was collected for hematoxylin-eosin (HE) and TUNEL staining to determine WMD and apoptosis. The distribution and morphology of microglial cells in the PVWM were studied using IBA1 immunofluorescence staining. Reactive oxygen species (ROS) kit was used to detect ROS. The expression of nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasomes, interleukin (IL)-1β, IL-18 and mitochondrial autophagy markers (pink1 and parkin) were determined using real-time quantitative PCR. Results:Compared with the sham group, the HI group showed WMD, cell degeneration and necrosis,increased cell apoptosis and increased expressions of NLRP3 inflammasomes and downstream inflammatory factors (IL-1β and IL-18) in PVWM. Compared with the HI group,the HI+MTn group showed reduced WMD, cell apoptosis, microglia infiltration and inflammatory factors expression. MTn increased pink1 and parkin expression and reduced ROS production in PVWM.Conclusions:MTn reduces ROS production by enhancing mitochondrial autophagy and inhibits NLRP3 inflammasomes hyperactivation to alleviate endotoxin- and HI-induced WMD in neonatal rats.