Ong J, Kerr D I
Eur J Pharmacol. 1983 Oct 28;94(3-4):305-12. doi: 10.1016/0014-2999(83)90419-3.
In isolated segments of the guinea-pig ileum, there was: (a) an early, short-lived (less than 20 s) depression by gamma-aminobutyric acid (GABA) of contractile responses to 5-hydroxytryptamine (5-HT), acetylcholine(ACh), or nicotine, also seen with 3-amino-1-propanesulphonic acid (3APS) or muscimol in place of GABA, and sensitive to bicuculline, picrotoxinin or piretanide, and (b) a delayed, longer-lasting (30 s-1 min) depression of responses to 5-HT and nicotine, but not exogenously applied ACh, also seen with baclofen and only antagonised by delta-aminovaleric acid (DAVA). At 25 degrees C, all these effects were still observed but slowed, whilst at 37 degrees C after cold storage (6 degrees C) overnight, the early, short-lived depression was reduced or eliminated, yet the delayed depression was enhanced. It is concluded that the early, short-lived depression is mediated through GABAA-receptor sites, and the delayed, longer-lasting depression through GABAB-receptor sites on neurones of the myenteric plexus; effects consistent with GABA being a neurotransmitter in the enteric nervous system.
在豚鼠回肠的离体节段中，存在以下情况：(a) γ-氨基丁酸（GABA）对5-羟色胺（5-HT）、乙酰胆碱（ACh）或尼古丁引起的收缩反应有早期、短暂（少于20秒）的抑制作用，用3-氨基-1-丙烷磺酸（3APS）或蝇蕈醇代替GABA时也可见到这种作用，且对荷包牡丹碱、印防己毒素或吡咯他尼敏感；(b) 对5-HT和尼古丁反应的延迟、持续时间更长（30秒 - 1分钟）的抑制作用，但对外源性应用的ACh无此作用，用巴氯芬时也可见到这种作用，且仅被δ-氨基戊酸（DAVA）拮抗。在25℃时，所有这些作用仍可观察到，但速度减慢，而在6℃冷藏过夜后于37℃时，早期、短暂的抑制作用减弱或消除，而延迟性抑制作用增强。结论是，早期、短暂的抑制作用是通过肌间神经丛神经元上的GABAA受体位点介导的，而延迟、持续时间更长的抑制作用是通过GABAB受体位点介导的；这些作用与GABA作为肠神经系统中的一种神经递质相一致。
