TLR4 and serum lipopolysaccharide activity: Endotoxemia in the newborn rats induced by increasing doses of LPS (5, 10 or 15 mg/kg/day × 5 days) resulted in significant and dose-dependent increase of TLR4 protein level in the acini incubated with caerulein (10−8 M) as compared to the group subjected to caerulein alone.