Effects and wavelet spectral entropy analysis of rhubarb extracts rhein on synaptic transmission in rat hippocampal ca1 area in vitro.
BACKGROUND
5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses lipid peroxidation in rat brain homogenates. This study was to assess the effects of anthraquinone derivatives, rhein on synaptic transmission in the rat hippocampal CA1 pyramidal cell layer by intracellular recording.


METHODS
The excitatory postsynaptic potential (EPSP) evoked by stimulation of the Schaffer collaterals in the presence of bicuculline (15 micromol/L) was depressed by application of rhein (0.3 - 30 micromol/L). The amplitude of the EPSP was restored within 20 minutes after removal of rhein from the supernatant. At a concentration of 30 micromol/L, rhein reduced the amplitude of the EPSP to 42% +/- 3.7% (n = 24) of the control. Subsequently, wavelet spectral entropy was used to analyze the EPSP.


RESULTS
A strong positive correlation was observed between the wavelet spectral entropy and other parameters such as amplitude, slope of rising phase and slope of descending phase of the EPSP. The paired-pulse facilitation (PPF) of the EPSP was significantly increased by rhein (30 micromol/L). The inhibitory postsynaptic potential (IPSP) recorded in the presence of CNQX (20 micromol/L) and APV (40 micromol/L) is not altered by rhein (30 micromol/L).


CONCLUSIONS
Rhein (30 micromol/L) can decrease the frequency but not the amplitude of the miniature EPSP (mEPSP). It is suggested that rhein inhibits excitatory synaptic transmission by decreasing the release of glutamate in rat hippocampal CA1 pyramidal neurons.
Gu
Jian-wen
JW
Institute of Biomedical Engineering, Xi'an Jiaotong University, Xi'an 710049, China. gujianwen2000@yahoo.com.cn
Zheng
Chong-xun
CX
Zhang
Ai-hua
AH
Hasuo
Hiroshi
H
Akasu
Takashi
T
Yang
Wen-tao
WT
Yang
Li-bin
LB
Xia
Xun
X
Ma
Yuan
Y
D000818:Animals; D000880:Anthraquinones / Q000737:chemistry / Q000494:pharmacology*; D019277:Entropy; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects*
D000880:Anthraquinones; C020491:rhein