Enteric-formulated lactoferrin was more effectively transported into blood circulation from gastrointestinal tract in adult rats.

We have previously demonstrated that intestinally infused bovine lactoferrin (bLF) is transported into the blood circulation via the lymphatic pathway, not via the portal circulation. Therefore, in the present study, we further investigated whether intragastrically infused enteric-formulated bLF (EF-bLF) was more efficiently absorbed than bLF from the intestine in adult rats. The rats were randomly divided into three groups: 30 and 300 mg kg(-1) non-enteric-formulated bLF (non-EF-bLF) groups and a 30 mg kg(-1) EF-bLF group. Thoracic lymph was collected from a thoracic lymph duct under general anaesthesia. Bovine lactoferrin was infused into the stomach or duodenal lumen via a needle for a period of over 1 min in a volume of 1 ml kg(-1). The bLF transported into the lymph was assayed quantitatively by double-antibody enzyme-linked immunosorbent assay (ELISA). Following the intragastric administration of bLF, the three groups showed almost the same lymph flow, but the bLF concentration in the lymph fluid in the EF-bLF group increased significantly and peaked 3 h after administration. With intraduodenal administration, the bLF concentration in the lymph fluid of the higher non-EF-bLF group was significantly higher than those of the other groups. The amount of absorbed bLF in the EF-bLF group was, however, about 10 times higher than that in the lower non-EF-bLF group, when it was administered intragastrically. These data show that enteric-formulated bLF is less susceptible to gastric pepsin and is more efficiently absorbed from the intestine than is non-enteric-formulated bLF.