Kastin A J, Akerstrom V
Veterans Affairs Medical Center and Tulane University School of Medicine, New Orleans, Louisiana 70112-1262, USA.
Am J Physiol. 1999 Mar;276(3):E479-82. doi: 10.1152/ajpendo.1999.276.3.E479.
Neuropeptide Y (NPY) is found and is active both in the periphery and brain, but its crossing of the blood-brain barrier (BBB) in either direction has not been measured. We used multiple time-regression analysis to determine that radioactively labeled NPY injected intravenously entered the brain much faster than albumin, with an influx constant of 2.0 x 10(-4) ml. g. -1. min-1. However, this rate of entry was not significantly changed by injection of 10 microgram/mouse of excess NPY, by leptin, or by food deprivation. HPLC showed that most of the NPY entering the brain was intact, and capillary depletion with and without washout showed that the NPY did not remain bound to endothelial cells or associated with vascular elements. Perfusion in a blood-free solution eliminated binding to serum proteins as an explanation for the lack of saturation. Efflux of labeled NPY from the brain occurred at the same rate as albumin, reflecting the normal rate of reabsorption of cerebrospinal fluid. Thus NPY can readily enter the brain from blood by diffusion across the BBB.
神经肽Y（NPY）在外周和大脑中均有发现且具有活性，但尚未测量其双向通过血脑屏障（BBB）的情况。我们采用多次时间回归分析来确定静脉注射放射性标记的NPY进入大脑的速度比白蛋白快得多，流入常数为2.0×10（-4）ml·g -1·min-1。然而，注射10微克/小鼠的过量NPY、瘦素或禁食后，这种进入速度并没有显著变化。高效液相色谱法显示，进入大脑的大部分NPY是完整的，有冲洗和无冲洗的毛细血管耗竭表明，NPY不会与内皮细胞结合或与血管成分相关。在无血溶液中灌注排除了与血清蛋白结合作为缺乏饱和性的解释。标记的NPY从大脑中的流出速度与白蛋白相同，反映了脑脊液正常的重吸收速度。因此，NPY可以通过扩散轻易地从血液进入大脑。
