The Role and Mechanism of Borneol to Open the Blood-Brain Barrier

Abstract

Background: The blood-brain barrier (BBB) is the greatest challenge in the treatment of intracranial malignant tumors.

Objective: The aim of this study is to determine the role of borneol in opening the BBB and elucidate the underlying mechanisms.

Materials and methods: Twenty Sprague-Dawley (SD) rats were randomized into borneol group intragastrically administered with 10% borneol corn oil (2 mL/kg) and control group. After 30 minutes, 2% Evans blue (4 mL/kg) was injected. Thirty minutes later, brain tissue was analyzed using the Evans blue standard curve. Another 40 SD rats were randomized into high-, medium-, and low-dose borneol groups and a control group. Each rat in the experimental groups was intragastrically administered with 10% borneol corn oil (2 mL/kg, 1.25 mL/kg, and 0.5 mL/kg, respectively). The control group was injected with corn oil of 1.25 mL/kg. After 30 minutes, the rats were killed, and the brain tissues were collected. The expression of occludin, occludens-1, nitric oxide synthase, P-glycoprotein, and intercellular cell adhesion molecule-1 (ICAM-1) was detected by immunohistochemy.

Results: The concentration of Evans blue in the borneol group was higher than in the control group ( P < .05). The mean density of ICAM-1 expression was higher in the experimental group than in the control group ( P < .05). In contrast, significant differences of positive area and total density of ICAM-1 were shown only between the high-dose group and the control group ( P < .05).

Conclusion: Borneol can open the BBB, which might be related with the increased expression of ICAM-1.

Keywords: ICAM-1; SD rats; blood-brain barrier; borneol; traditional Chinese medicine.

Figure 1.

Standard curve of Evans blue.

Figure 2.

The expression of occludin, ZO-1, NOS, P-gp, and ICAM-1 detected by immunochemistry. (A) Occluding, mainly located in the nucleus of glial cells and neurons. (B) ZO-1, mainly located in the cytoplasm of glial cells and neurons. (C) NOS, mainly located in the cytoplasm of neurons and vascular endothelial cells. (D) P-gp, mainly located in the cytoplasm of neurons. (E) ICAM-1, mainly located in the cytoplasm of vascular endothelial cells.