据美《化学与工程新闻》报道:由于脑的化学特别精细,所以脑受到特别的保护,以免受周围化学物质的影响。在供给脑营养物质及带走脑废物的血管和脑细胞本身之间产生了一个高效能的屏障。此屏障系统的工作很圆满,因而在脑化学发生差错时,则成为一个重要的障碍,使治疗药物一般不能进入脑内。保护脑的这屏障,在普通情况下也将有用的药物排除于脑外。 According to the U.S. Chemical and Engineering News, the brain is specially protected from the chemicals in its surroundings due to the particularly fine chemical chemistry of the brain. A high-performance barrier is created between the blood vessels that supply brain nutrients and carry brain waste, and the brain cells themselves. This barrier system works very well and therefore becomes an important hurdle in the brain chemistry where the therapeutic drugs generally can not enter the brain. This barrier to the protection of the brain, in normal circumstances, also excludes useful drugs from the brain.