Gray J A, Green A R
Br J Pharmacol. 1987 Jul;91(3):517-22. doi: 10.1111/j.1476-5381.1987.tb11244.x.
The effect of baclofen, the GABAB-agent, on the potassium-evoked release of endogenous 5-hydroxytryptamine (5-HT) from slices of mouse frontal cortex has been investigated. The release of endogenous 5-HT evoked by addition of K+ (35 mM) was inhibited by (+/-)-baclofen in a dose-dependent manner with an IC50 of 0.1 microM. Inhibition of K+-evoked release of 5-HT was produced by (+/-)- and (-)-baclofen but not (+)-baclofen. This action of the (-)-enantiomer was not altered by the presence of the (+)-enantiomer. Addition of GABA (0.1-10 microM) also induced a dose-dependent inhibition of 5-HT release. This effect was neither enhanced by flurazepam (1 microM) nor antagonized by bicuculline (10 microM). The progabide metabolite, 4-[( (4-chlorophenyl) (5-fluoro-2-hydroxyphenyl)methylene]amino)butyric acid (SL75.102) (1 microM) inhibited the K+-evoked release of 5-HT by 61%. These data suggest that baclofen is a potent inhibitor of the K+-evoked release of endogenous 5-HT from the cortex and further indicate that the release of 5-HT may be controlled by a GABAB-receptor located presynaptically.
已研究了γ-氨基丁酸B(GABAB)受体激动剂巴氯芬对小鼠额叶皮质切片中钾离子诱发的内源性5-羟色胺(5-HT)释放的影响。添加K+(35 mM)诱发的内源性5-HT释放受到(±)-巴氯芬的剂量依赖性抑制,半数抑制浓度(IC50)为0.1μM。(±)-和(-)-巴氯芬可抑制钾离子诱发的5-HT释放,但(+)-巴氯芬则无此作用。(-)-对映体的这一作用不受(+)-对映体存在的影响。添加γ-氨基丁酸(GABA,0.1 - 10μM)也可诱导5-HT释放的剂量依赖性抑制。氟西泮(1μM)既不增强此效应,荷包牡丹碱(10μM)也不拮抗此效应。普罗加比的代谢产物4-[((4-氯苯基)(5-氟-2-羟基苯基)亚甲基]氨基丁酸(SL75.102)(1μM)可使钾离子诱发的5-HT释放抑制61%。这些数据表明,巴氯芬是皮质中钾离子诱发的内源性5-HT释放的有效抑制剂,并进一步表明5-HT的释放可能受突触前GABAB受体的调控。