.....More recently, α-Syn has been found in body fluids, including blood and cerebrospinal fluid, and is likely produced by both peripheral tissues and the central nervous system. Exchange of α-Syn between the brain and peripheral tissues could have important pathophysiologic and therapeutic implications. However, little is known about the ability of α-Syn to cross the blood-brain barrier (BBB). Here, we found that radioactively labeled α-Syn crossed the BBB in both the brain-to-blood and the blood-to-brain directions at rates consistent with saturable mechanisms. Low-density lipoprotein receptor-related protein-1 (LRP-1), but not p-glycoprotein, may be involved in α-Syn efflux and lipopolysaccharide (LPS)-induced inflammation could increase α-Syn uptake by the brain by disrupting the BBB.