Yuan X R
Department of Physiology, Nanjing Medical University, China.
Zhongguo Yao Li Xue Bao. 1996 May;17(3):278-80.
To compare the inhibitory effects of 3 opioid receptor agonists, (D-Ala2, NMe-Phe4, Gly-ol)-enkephalin (DAGO), (D-Pen2,5)-enkephalin (D-PEN), and trans-(+/-)-3, 4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]-benzeneacetamide methanesulfonate (U-50488H) in different concentrations on synaptic transmission.
The excitatory postsynaptic potentials (EPSP) in slice preparation of nucleus accumbens of rats were recorded using electric stimulation of the olfactory tubercle area and intracellular micropipettes filled with potassium acetate (3 mol.L-1).
Superfusion of DAGO, D-PEN, and U-50488H (1 mumol.L-1) reduced the amplitude of EPSP and the inhibitory effect on EPSP were reversed by superfusing naloxone (Nal, 1 mumol.L-1), in which the DAGO-induced reduction of synaptic transmission was the most effective. The depolarizing responses to microiontophoretic injection of glutamate were reduced by superfusing DAGO in 19 neurons of slice preparation of nucleus accumbens.
The inhibitory effects of DAGO, D-PEN, and U-50488H on EPSP were in a concentration-dependent manner, and the mechanism of opioid agonists (at least DAGO) reducing EPSP was related to a decrease of postsynaptic transmission mediated by glutamate.
比较3种阿片受体激动剂，即（D-丙氨酸2，N-甲基苯丙氨酸4，甘氨醇）-脑啡肽（DAGO）、（D-青霉胺2,5）-脑啡肽（D-PEN）和反式-（+/-）-3,4-二氯-N-甲基-N-[2-（1-吡咯烷基）环己基]-苯乙酰胺甲磺酸盐（U-50488H）在不同浓度下对突触传递的抑制作用。
采用电刺激嗅结节区，并用充满醋酸钾（3 mol.L-1）的细胞内微电极记录大鼠伏隔核脑片制备中的兴奋性突触后电位（EPSP）。
灌注DAGO、D-PEN和U-50488H（1 μmol.L-1）可降低EPSP的幅度，灌注纳洛酮（Nal，1 μmol.L-1）可逆转对EPSP的抑制作用，其中DAGO诱导的突触传递减少最为有效。在19个伏隔核脑片制备的神经元中，灌注DAGO可降低对微量离子电泳注射谷氨酸的去极化反应。
DAGO、D-PEN和U-50488H对EPSP的抑制作用呈浓度依赖性，阿片类激动剂（至少DAGO）降低EPSP的机制与谷氨酸介导的突触后传递减少有关。
