Barrera C M, Banks W A, Kastin A J
VA Medical Center, New Orleans, LA 70146.
Brain Res Bull. 1989 Dec;23(6):439-42. doi: 10.1016/0361-9230(89)90186-x.
Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) has been shown to be transported from the brain to blood by a saturable system shared with Met-enkephalin and a few other substances. It is not known whether a similar system exists in the opposite direction. Accordingly, the entry rate of 125I-Tyr-MIF-1 from blood to brain was measured by a method involving perfusion of the test substances into the common carotid artery. The rate of entry was obtained from the slope of the line determined by brain to blood ratios at multiple points of time. Penetration of 125I-Tyr-MIF-1 across the blood-brain barrier was found to be 4.444 x 10(-3) ml/g/min, an entry rate significantly higher than that of the vascular marker 125I-albumin. Competition with Tyr-MIF-1 or nonradioactively labeled 127I-Tyr-MIF-1 showed no difference in rate of entry, indicating that the penetration of 125I-tyr-MIF-1 was not saturable. Met-enkephalin and Leu-enkephalin also failed to affect entry of 125I-Tyr-MIF-1. The results indicate that Tyr-MIF-1 can enter the brain from the blood to a greater extent than does albumin, but that this penetration does not involve a saturable system.
酪氨酰 - 促黑素细胞激素 -1（酪氨酰 - 脯氨酰 - 亮氨酰 - 甘氨酰胺）已被证明可通过与甲硫氨酸脑啡肽及其他几种物质共享的可饱和系统从脑转运至血液。尚不清楚是否存在相反方向的类似系统。因此，采用将测试物质灌注到颈总动脉的方法来测量125I - 酪氨酰 - 促黑素细胞激素 -1从血液进入脑的速率。进入速率由多个时间点的脑血比所确定的直线斜率得出。发现125I - 酪氨酰 - 促黑素细胞激素 -1穿过血脑屏障的速率为4.444×10⁻³毫升/克/分钟，该进入速率显著高于血管标记物125I - 白蛋白。与酪氨酰 - 促黑素细胞激素 -1或非放射性标记的127I - 酪氨酰 - 促黑素细胞激素 -1竞争，进入速率未显示差异，表明125I - 酪氨酰 - 促黑素细胞激素 -1的穿透不饱和。甲硫氨酸脑啡肽和亮氨酸脑啡肽也未能影响125I - 酪氨酰 - 促黑素细胞激素 -1的进入。结果表明，酪氨酰 - 促黑素细胞激素 -1从血液进入脑的程度比白蛋白更大，但这种穿透不涉及可饱和系统。
