Luzzi S, Maggi C A, Spagnesi S, Santicioli P, Zilletti L
J Auton Pharmacol. 1985 Mar;5(1):65-9. doi: 10.1111/j.1474-8673.1985.tb00566.x.
The potential interaction of 5-aminovaleric acid (5-AVA) on GABAA and GABAB receptors was investigated on the guinea-pig isolated ileum myenteric plexus preparation. In the unstimulated preparation 5-AVA (0.1-3 mM) produced a transient contraction which was abolished by previous exposure to picrotoxin (0.1 mM), atropine (3 microM) or tetrodotoxin (0.3 microM). Cross desensitization was observed between the contractile effects of 5-AVA and GABA, while a previous exposure to (+/-)-baclofen did not affect 5-AVA induced contractions. 5-AVA antagonized the relaxant effect of (+/-)-baclofen in unstimulated preparations. 5-AVA (1 mM) had no effect on amplitude of twitches in supramaximally stimulated preparations while GABA produced a concentration related inhibition. In the presence of 5-AVA (1 mM) the concentration response curve to GABA was shifted to the right without a reduction of the maximal effect attainable. These observations indicate that 5-AVA interacts with both GABAA and GABAB receptors in guinea-pig ileum. The concentrations required to observe a GABAA effect are of the same order as those which are effective in producing a blockade of GABAB mediated responses.
在豚鼠离体回肠肌间神经丛标本上研究了5-氨基戊酸（5-AVA）对GABAA和GABAB受体的潜在相互作用。在未受刺激的标本中，5-AVA（0.1 - 3 mM）引起短暂收缩，预先暴露于印防己毒素（0.1 mM）、阿托品（3 microM）或河豚毒素（0.3 microM）可消除该收缩。5-AVA和GABA的收缩效应之间观察到交叉脱敏，而预先暴露于（±）-巴氯芬并不影响5-AVA诱导的收缩。5-AVA拮抗未受刺激标本中（±）-巴氯芬的舒张效应。5-AVA（1 mM）对超强刺激标本中的抽搐幅度无影响，而GABA产生浓度相关的抑制作用。在存在5-AVA（1 mM）的情况下，GABA的浓度 - 反应曲线向右移动，而可达到的最大效应未降低。这些观察结果表明，5-AVA在豚鼠回肠中与GABAA和GABAB受体均相互作用。观察到GABAA效应所需的浓度与有效阻断GABAB介导反应的浓度处于同一数量级。
