Regulation of synaptic acetylcholine concentrations by acetylcholine transport in rat striatal cholinergic transmission
Regulation of synaptic acetylcholine concentrations by acetylcholine transport in rat striatal cholinergic transmission
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大鼠纹状体胆碱能传递中乙酰胆碱转运对突触乙酰胆碱浓度的调节
DOI：
10.1111/jnc.14127
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发表时间：
2017
影响因子：
4.7
通讯作者：
Taniguchi Takanobu
中科院分区：
文献类型：
--
作者：
Muramatsu Ikunobu;Uwada Junsuke;Masuoka Takayoshi;Yoshiki Hatsumi;Sada Kiyonao;Lee Kung-Shing;Nishio Matomo;Ishibashi Takaharu;Taniguchi Takanobu
除了被乙酰胆碱酯酶（AChE）水解外，乙酰胆碱（ACh）也直接被脑组织吸收。在这项研究中，我们研究是否摄取乙酰胆碱参与调节突触乙酰胆碱浓度。使用超小型灌流容器对用[3 H]胆碱预孵育的大鼠纹状体节段进行灌流实验，该灌流容器旨在最大限度地减少灌流液在容器内的滞留。在灌流实验中，浓度低于1 μM的半胆碱盐-3（HC-3）选择性抑制高亲和力胆碱转运蛋白1对[3 H]胆碱的摄取，对基础和电诱发的[3 H]流出无影响。相比之下，高浓度的HC-3以及四乙基铵（>10 μM）抑制[3 H]胆碱和[3 H]ACh的摄取，增加基础[3 H]溢出并增强电诱发的[3 H]流出。HC-3和四乙基铵的这些作用也在组织AChE被二异丙基氟磷酸盐不可逆灭活的条件下观察到。具体而言，诱发的[3 H]外排的增强作用在AChE灭活制剂中显著更高，并被阿托品减弱。另一方面，用[3 H]ACh预孵育的纹状体段未能增加对电刺激的响应的[3 H]溢出。这些结果表明，突触ACh浓度显着调节突触后摄取ACh，以及通过乙酰胆碱酯酶水解和调制ACh释放介导的突触前毒蕈碱ACh受体。此外，这些数据表明，ACh衍生胆碱的再循环可能在胆碱能末梢中是次要的。本研究揭示了中枢神经系统胆碱能传递的新机制。
In addition to hydrolysis by acetylcholine esterase (AChE), acetylcholine (ACh) is also directly taken up into brain tissues. In this study, we examined whether the uptake of ACh is involved in the regulation of synaptic ACh concentrations. Superfusion experiments with rat striatal segments pre‐incubated with [3H]choline were performed using an ultra‐mini superfusion vessel, which was developed to minimize superfusate retention within the vessel. Hemicholinium‐3 (HC‐3) at concentrations less than 1 μM, selectively inhibited the uptake of [3H]choline by the high affinity‐choline transporter 1 and had no effect on basal and electrically evoked [3H]efflux in superfusion experiments. In contrast, HC‐3 at higher concentrations, as well as tetraethylammonium (>10 μM), which inhibited the uptake of both [3H]choline and [3H]ACh, increased basal [3H]overflow and potentiated electrically evoked [3H]efflux. These effects of HC‐3 and tetraethylammonium were also observed under conditions where tissue AChE was irreversibly inactivated by diisopropylfluorophosphate. Specifically, the potentiation of evoked [3H]efflux was significantly higher in AChE‐inactivated preparations and was attenuated by atropine. On the other hand, striatal segments pre‐incubated with [3H]ACh failed to increase [3H]overflow in response to electrical stimulation. These results show that synaptic ACh concentrations are significantly regulated by the postsynaptic uptake of ACh, as well as by AChE hydrolysis and modulation of ACh release mediated through presynaptic muscarinic ACh receptors. In addition, these data suggest that the recycling of ACh‐derived choline may be minor in cholinergic terminals. This study reveals a new mechanism of cholinergic transmission in the central nervous system.