Petty M A, De Jong W
Eur J Pharmacol. 1982 Jul 16;81(3):449-57. doi: 10.1016/0014-2999(82)90110-8.
The cardiovascular effects of beta-endorphin after administration directly into the nucleus tractus solitari (NTS) of urethane-anaesthetised rats were investigated. Unilateral injection resulted in a U-shaped dose-response relationship with a fall in mean arterial pressure and heart rate occurring at low doses (less than 10 ng). No change in respiratory frequency was observed at any of the doses examined. The hypotensive effects of beta-endorphin were anatomically specific and restricted to the NTS. The depressor response was prevented and bradycardia reduced by naloxone (1 mg/kg s.c. or 10 ng injected into the NTS) and also by beta-endorphin antiserum (1:50 dilution) but not by antiserum to [Met5]enkephalin (1:50 dilution) applied locally into the NTS. The beta-endorphin antiserum caused a rise in blood pressure when administered alone. Conversely microinjection of antiserum to [Met 5]enkephalin resulted in a brief depressor response. Doses of beta-endorphin larger than 10 ng induced a rise in blood pressure accompanied by variable effects on heart rate. Similarly unilateral administration of Des-tyr-endorphin (100 pg) resulted in a blood pressure increase and [D-Ala2,Met5]enkephalin produced a dose-related pressor response and tachycardia. The results indicate that at least two separate endorphin systems are involved in cardiovascular control at the level of NTS, one being depressor in nature (beta-endorphin-like) and the other pressor ([met5]enkephalin-like).
研究了将β-内啡肽直接注入氨基甲酸乙酯麻醉大鼠的孤束核（NTS）后对心血管系统的影响。单侧注射呈现U形剂量反应关系，低剂量（小于10纳克）时平均动脉压和心率下降。在所研究的任何剂量下，呼吸频率均未观察到变化。β-内啡肽的降压作用具有解剖学特异性，且局限于NTS。纳洛酮（1毫克/千克皮下注射或10纳克注入NTS）以及β-内啡肽抗血清（1:50稀释）可预防降压反应并减轻心动过缓，但局部注入NTS的[甲硫氨酸5]脑啡肽抗血清（1:50稀释）则无此作用。单独给予β-内啡肽抗血清会导致血压升高。相反，微量注射[甲硫氨酸5]脑啡肽抗血清会引发短暂的降压反应。大于10纳克的β-内啡肽剂量会导致血压升高，并对心率产生不同影响。同样，单侧给予去酪氨酸内啡肽（100皮克）会导致血压升高，[D-丙氨酸2，甲硫氨酸5]脑啡肽会产生剂量相关的升压反应和心动过速。结果表明，至少有两个独立的内啡肽系统参与了NTS水平的心血管控制，一个本质上是降压的（β-内啡肽样），另一个是升压的（[甲硫氨酸5]脑啡肽样）。
