Objective: This study aimed to investigate the roles of platelet activating factor (PAF) receptor antagonist in damage to intestinal mucin-2 (MUC2) during endotoxemia on young rats.
Methods: Eighteen-day-old Wistar rats were randomized to be treated with lipopolysaccharide (LPS) (5 mg/kg), LPS plus PAF receptor antagonist and normal saline injection (control). PAF receptor antagonist BN52021 5 mg/kg was administered 30 minutes before or after LPS injection (pretreatment group or treatment group). The ileum specimens (n = 8) were harvested at 1.5, 3, 6, 24, 48 and 72 hours after LPS injection. Transmission electron microscopy was used for morphologic evaluation. Immunohistochemistry was used to determine MUC2 in intestinal mucosa.
Results: Microvilli and tight junctions were intact in the control group. Enlargement of tight junctions were seen in the LPS group and microvilli were thin, rare or disrupted, shed. The rough endoplasmic reticulum, mitochondria, and glycogen particles were injured. The changes of the pretreatment and treatment group were slightly milder than that in the LPS group. Ileum of a control rat in which a thin layer of mucus covering the epithelial surface and mucin-containing goblet cells appeared very distended. The experiment group showed a decrease or irregularly distributed membranous mucus expression. The MUC2 content of absorbance significantly decreased in the LPS challenged group compared with that in the control group (P < 0.01), and reached a nadir at 6 hours (0.1841 +/- 0.0047) vs. the control group (0.2091 +/- 0.0060) (P < 0.01). The tendency of the level of MUC2 in the pretreatment and treatment group was the same as that of the LPS group, and the level of MUC2 in the pretreatment and treatment group was higher than that in the LPS group at each time point. ANOVA analysis showed that the inter-group and intra-group difference had statistical significance (P < 0.05).
Conclusions: PAF may play some roles in the injury of intestinal mucus barrier function during endotoxemia. Preventive and remedial use of PAF receptor antagonist BN52021 may relieve intestinal injury.