Issue Archive

Morphine blocked the exitatory amino acid mediated membrane current in ambigual motoneurons of the rat

Zhang Min, Nie Lin, Liu Lei, Wang Y T, Neuman R S, Bieger D

Department of Physiology, Shandong Medical University. Jinan 250012, Shandong

Abstract

Excitatory postsynaptic potentials(EPSPs) and responses of neurons in the compact formation of the neucleus ambiguus(AMBc) to pressure-ejected or bath-applied test substances were recorded intracellularly from sagittal slices of Sprague-Dawley rat medulla containing subnucleus centralis of solitary complex(NTSc), AMBc and solitarioambigual pathway. In 5 cells, recorded spontaneous EPSPs could be blocked by morphine (3--5pmol) to AMBc. Electrical stimulation of NTSc evoked EPSPs in AMBc neurons, the amplitude of which were decreased to 71.1±6.2%(P<0.001) with the addition to morphine. The morphine effect could be abolished by bath-applied naloxone (50nmol/L). The amplitude of membrane depolarization induced by pressure-ejected N-methyl-D-aspartate (NMDA, 0.5--1.0pmol), acetylcholine (3 pmol) and quisqualate(0.1--0.5pmol) to NTSc could also be decreased by bath-applied morphine(10 #mu#mol/L) respectively to 38.1±5.7%(P<0.001), 32.8±5.5%(P<0.01) and 29.6±7.1%(P<0.05).

Key words: NMDA;AMPA;Compact formation of the neucleus ambiguus;Morphine ;

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Zhang Min, Nie Lin, Liu Lei, Wang Y T, Neuman R S, Bieger D. Morphine blocked the exitatory amino acid mediated membrane current in ambigual motoneurons of the rat. Acta Physiol Sin 1995; 47 (3): (in Chinese with English abstract).