大鼠脊髓蛛网膜下腔注射氟安定对下丘脑防御反应的影响及其机制

MECHANISM OF EFFECT OF INTRATHECAL APPLICATION OF FLURAZEPAM ON PRESSOR RESPONSE INDUCED BY HYPOTHALAMIC STIMULATION IN THE RAT

对55只大鼠行脊髓蛛网膜下腔注射氟安定、Υ-氨基丁酸(GABA)、荷包牡丹碱和3-aminopropane sulfonic acid(3APS)进行血压观察.结果表明,氟安定和GABA都可抑制基础动脉血压(SBP)和抑制刺激下丘脑防御反应区诱发的升压反应(SBPmax).GABA-A受体拮抗剂荷包牡丹碱对SBP,SBPmax均无明显作用,而在荷包牡丹碱基础上,再给予氟安定,降低SBP,SBPmax的作用不再出现.GABA-B受体拮抗剂3APS可使SBP和SBPmax增加;在此基础上,再给予氟安定,则氟安定降低SBP和SBPmaX的作仍出现.提示在脊髓水平,氟安定有抑制动脉血压和抑制刺激下丘脑诱发的升压反应的作用.这种抑制作用可能与脊髓内GABA-A受体则激活有关,而GABA-B受体可能不参与此作用.

In experiments performed on 55 Wistsr rats, we observed the effects of intrathecal application of flurazepam, gamma-aminobutyric acid (GABA), bicuculline and 3-amino-propane sulfonic acid (3APS) on the pressor response and blood pressure. The results were as follows: ① Both flurazepam and GABA resulted in a significant decrease in the systolic blood pressure (SBP) and the pressor response during hypothalamic stimulation (SBPmax). ② GABA-A receptor antagonist bicuculline brought no significant changes in SBP and SBPmax. When the administration of flurazepam was followed by the injection of bicuculline, the suppresive effects on SBP and SBPmax were no longer observed. ③ Intrathecal injection of GABA-B receptor antagonist 3APS increased SBP and SBPmax. When the injection of flurazepam was followed by 3APS, the depressing effects of flurazepam on SBP and SBPmax still existed. These results show that flurazepam in the spinal cord inhibits the pressor response evoked by hypothalamic stimulation and de creases the arterial blood pressure. Such inhibitory actions may be involved in the mediation of the activation of the GABA-A receptor rather than the GABA-B receptor in the spinal cord.