Kastin Abba J, Pan Weihong
Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
Curr Pharm Des. 2008;14(16):1615-9. doi: 10.2174/138161208784705423.
The two main ways for peptides in the peripheral body to enter the brain are by either saturable transport or passive diffusion across the blood-brain barrier (BBB). Saturable transport systems have the advantage of being responsive to physiological and pathological stimuli. Since saturable systems can regulate peptide entry into the brain, they have the potential to play controlling roles in feeding behavior. For therapeutic applications, however, saturable systems have the disadvantage of functioning as a threshold to limit access of large amounts of peptides into the brain. This pharmacological problem presumably would not be encountered for peptides crossing the BBB by passive diffusion, a process dependent on physicochemical properties. Thus, the gatekeeper function of the BBB can be expanded to a primary governing role, especially for entry of ingestive peptides subject to their respective saturable transport systems.
外周体内的肽进入大脑的两种主要方式是通过饱和转运或被动扩散穿过血脑屏障（BBB）。饱和转运系统的优点是对生理和病理刺激有反应。由于饱和系统可以调节肽进入大脑，它们有可能在进食行为中发挥控制作用。然而，对于治疗应用来说，饱和系统的缺点是起到了一个阈值的作用，限制了大量肽进入大脑。对于通过被动扩散穿过血脑屏障的肽来说，可能不会遇到这个药理学问题，被动扩散过程取决于物理化学性质。因此，血脑屏障的守门人功能可以扩展到主要的控制作用，特别是对于受各自饱和转运系统影响的摄入性肽的进入。
