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[Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro.] [Article in Chinese]

LUO Hao, QIN Wen, ZHANG Yan, WANG Bang-An, WANG Meng-Ya^*

Cell Electrophysiology Laboratory, Wannan Medical College, Wuhu 241002, China

Abstract

The aim of the present study is to observe the receptor kinetics property of long-term potentiation (LTP) of excitatory postsynaptic potential (EPSP) in spinal cord motoneurons (MNs) by descending activation. The intracellular recording techniques were conducted in spinal cord MNs of neonatal rats aged 8-14 days. The changes of EPSP induced by ipsilateral ventrolateral funiculus (iVLF) stimulation (iVLF-EPSPs) were observed, and receptor kinetics of iVLF-EPSPs were analyzed. The results showed that, the amplitude, area under curve and maximum left slope of EPSP were positively correlated with stimulus intensity (P < 0.05 or P < 0.01), while the apparent receptor kinetic parameters apparent dissociation rate constant (K₂), apparent equilibrium dissociation constant (K_T) of EPSP were negatively correlated with stimulus intensity (P < 0.01 or P < 0.05). The iVLF-EPSPs were persistently increased after tetanic stimulation (100 Hz, 50 pulses/train, duration 0.4-1.0 ms, 6 trains, main interval 10 s, 10-100 V) in 5 of 11 tested MNs. The amplitude of iVLF-EPSPs was potentiated to more than 120% of baseline and lasted at least 30 min, which could be referred to as iVLF-LTP. Meanwhile, the area under curve and maximum left slope of EPSPs were also increased to more than 120% of baseline. During iVLF-LTP, apparent receptor kinetics analyses of iVLF-EPSPs indicated that K₂ and K_T were decreased significantly to less than 80% of the baseline within 10 min and gradually and partially recovered in 3 MNs. These results of receptor kinetics analyses of iVLF-EPSPs suggest a possible enhancement in affinity of postsynaptic receptors in the early stage of iVLF-LTP in some MNs.

Key words: Spinal cord; motoneurons; descending activation; long-term potentiation; receptor kinetics

Received: 2013-08-19　　Accepted: 2013-12-13

Corresponding author: 汪萌芽　　E-mail: wangmy@wnmc.edu.cn

Citing This Article：

LUO Hao, QIN Wen, ZHANG Yan, WANG Bang-An, WANG Meng-Ya. [Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro.] [Article in Chinese]. Acta Physiol Sin 2014; 66 (2): 129-134 (in Chinese with English abstract).