[Effect of intracerebral injection of substance P on serotonin contents of several brain regions and its relation with pain threshold, electroacupuncture analgesia in rats].
The purpose of this study is to observe the effect of intracerebroventricular (icv) and intra-PAG injection of substance P (SP) on serotonin (5-HT) contents of hypothalamus, hippocampus, striatum and its relation with the change of pain threshold, electroacupuncture (EA) analgesia. The results were as follows: (1) After icv injection of SP, the pain threshold and the 5-HT contents of hypothalamus, hippocampus were significantly increased. After depletion of the 5-HT contents in brain by pCPA, the inhibitor of 5-HT synthesis, the effect of SP on elevating pain threshold and the 5-HT contents of hypothalamus, hippocampus were markedly attenuated, bud did not prevent the analgesic effect of SP (2) The pain threshold and the 5-HT contents of hypothalamus, hippocampus were dose-dependently increased by intra-PAG injection of SP. (3) The intra-PAG injection of SP introduced simultaneously with high or low frequency EA did not affect the change of 5-HT contents of three brain regions, but caused a more marked elevation of pain threshold. These results suggest that the serotoninergic system may be activated by PAG for the mediation of SP induced analgesia. There is a synergic action of analgesia between the effects produced by intra-PAG injection of SP and those by high or low frequency EA.
Li
X
X
Department of Physiology, Third Military Medical College, Chongqing.
Zhao
B
B
Ruan
H
H
Li
H
H
Liu
Z
Z
D015667:Acupuncture Analgesia; D000818:Animals; D001921:Brain / Q000378:metabolism*; D015671:Electroacupuncture; D005260:Female; D007276:Injections, Intraventricular; D008297:Male; D008845:Microinjections; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000494:pharmacology*
D012701:Serotonin; D013373:Substance P