Wayner M J, Polan-Curtain J, Armstrong D L
Division of Life Sciences, University of Texas at San Antonio 78249-0662, USA.
Peptides. 1995;16(6):1079-82. doi: 10.1016/0196-9781(95)00089-3.
We previously reported that injection of 1.0 microliter of 4.78 microM angiotensin II (AII) above the hippocampus in rats inhibits long-term potentiation (LTP) induction in medial perforant path-stimulated dentate granule cells. The present experiments were conducted in urethane-anesthetized Sprague-Dawley rats. LTP was measured in terms of the relative change in slope of the population EPSP compared to baseline. Effects of 0.48, 0.956, 1.195, 2.39, and 4.78 microM AII and time delays of 30, 60, 90, and 150 min with the 4.78 microM dose were determined. Results were significant and demonstrate that AII inhibition of LTP in dentate granule cells is both dose and time dependent. The threshold is approximately 1.0 pmol of peptide. Inhibition due to the 4.78 microM AII begins slowly after 1 h and is complete over the next 30 min, continues for another 30 min, and then fully recovers by the end of the next 30 min. This time dependency could be due to the internalization of the AII, interaction with a cytosolic receptor, and eventual degradation.
我们之前报道过，向大鼠海马体上方注射1.0微升4.78微摩尔/升的血管紧张素II（AII）会抑制内侧穿通通路刺激的齿状颗粒细胞中的长时程增强（LTP）诱导。本实验在乌拉坦麻醉的斯普拉格-道利大鼠中进行。LTP通过群体兴奋性突触后电位（EPSP）斜率相对于基线的相对变化来测量。测定了0.48、0.956、1.195、2.39和4.78微摩尔/升AII的作用以及4.78微摩尔/升剂量下30、60、90和150分钟的时间延迟。结果具有显著性，表明AII对齿状颗粒细胞中LTP的抑制作用具有剂量和时间依赖性。阈值约为1.0皮摩尔肽。4.78微摩尔/升AII引起的抑制在1小时后开始缓慢，在接下来的30分钟内完成，持续另外30分钟，然后在下一个30分钟结束时完全恢复。这种时间依赖性可能是由于AII的内化、与胞质受体的相互作用以及最终的降解。
