[The role of substance P in electroacupuncture analgesia and its relation to enkephalins in the rat brain].
In order to understand the role of substance P (SP) in the brain and the relationship between SP and enkephalins in the electroacupuncture analgesia (EA), we have observed the influence of SP-antagonist, (D-Arg', D-Phe5, D-Trp7.9, Leu11) -SP (DADPDTL) injected intracerebroventricularly (icv) on EA and the change of the level of SP in the brain regions of the rat during EA. We have made a further observations on the influences of the naloxone (NX) on the che change of the content of SP induced by EA and DADPDTL on the increase in Leu-enkephalins (LEK) induced by EA. The Wistar rats were used in the experiment. The latency of the tail flick, immersing the tip of rat tail (4 cm) into hot-water of 50 degrees C, was taken as the pain threshold. The drugs were injected icv via plastic cannulae implanted in the bilateral ventricles. The EA was applied to the point of "Zusanli" (S36). The contents of SP and LEK were determined radioimmunoassay in the hypothalamus, mid-brain, striatum and pons-medulla-oblongata. The pain threshold was increased by 48 +/- 9% (P less than 0.01) after EA. But icv injection of DADPDTL decreased the pain threshold by 14 +/- 7% after EA. The result suggests that DADPDTL can antagonize the effect of EA and that SP in the brain is involved in EA. After EA the contents of SP in the hypothalamus and mid-brain of the rats were decreased by 29% and 28% in comparison with that of the control group respectively (both of them, P less than 0.05), but the contents of SP in the striatum and pons-medulla-oblongata had no significant change.(ABSTRACT TRUNCATED AT 250 WORDS)
Institute of Acupuncture and Moxibustion, China Academy of Traditional Chinese Medicine, Beijing.
Y
Y
Deng
W
W
Cao
Z
Z
Lu
D015667:Acupuncture Analgesia; D000818:Animals; D001921:Brain / Q000378:metabolism*; D015671:Electroacupuncture; D004743:Enkephalin, Leucine / Q000378:metabolism*; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds; D013373:Substance P / Q000378:metabolism / Q000502:physiology*
D013373:Substance P; D004743:Enkephalin, Leucine