Sanger G J, McClelland C M
Eur J Pharmacol. 1986 Aug 15;127(3):179-85. doi: 10.1016/0014-2999(86)90362-6.
In gastrointestinal tissues such as rat stomach, exogenous 5-hydroxytryptamine (5HT) has little or no ability to affect nerve activity. However, endogenous 5HT might act differently, and this was investigated by stimulating 5HT synthesis using 5-hydroxy-L-tryptophan (5HTP). In longitudinal strips of rat forestomach, 5HTP (50 and 500 microM) increased cholinergically mediated contractions evoked by electrical field stimulation, probably by facilitating acetylcholine release; contractions evoked by exogenous acetylcholine were unaffected by 5HTP. The ability of 5HTP to increase electrically evoked contractions was long-lasting, required the presence of pyridoxal (a monoamine decarboxylase cofactor) and was reduced by the decarboxylase inhibitor carbidopa, but not by 6-hydroxydopamine. In the presence of paroxetine and nialamide, the 5HTP-induced increase in cholinergically mediated contractions was short-lasting. In anaesthetised rats 5HTP caused stimulation of gastric motility, which was blocked or reduced by atropine. These findings suggest that in the rat 5HTP stimulates gastric cholinergic activity, by increasing the concentration of 5HT at sites which normally synthesise 5HT.
在诸如大鼠胃等胃肠道组织中，外源性5-羟色胺（5HT）对神经活动几乎没有影响或根本没有影响。然而，内源性5HT的作用可能不同，为此通过使用5-羟基-L-色氨酸（5HTP）刺激5HT合成进行了研究。在大鼠前胃纵行肌条中，5HTP（50和500微摩尔）增加了电场刺激诱发的胆碱能介导的收缩，这可能是通过促进乙酰胆碱释放实现的；外源性乙酰胆碱诱发的收缩不受5HTP影响。5HTP增加电诱发收缩的能力持久，需要吡哆醛（一种单胺脱羧酶辅因子）的存在，并且被脱羧酶抑制剂卡比多巴降低，但不受6-羟基多巴胺影响。在帕罗西汀和尼亚酰胺存在的情况下，5HTP诱导的胆碱能介导收缩的增加是短暂的。在麻醉大鼠中，5HTP引起胃动力刺激，阿托品可阻断或减弱这种刺激。这些发现表明，在大鼠中，5HTP通过增加正常合成5HT部位的5HT浓度来刺激胃胆碱能活性。
