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Mutual potentiation of the analgesic effects of [met~(5)] enkephalin,dynorphia A-(1-13) and morphine in the spinal cord of the rat

Huang Long, Ren Mingfeng, Lu Junhua, Han Jisheng

Department of Physiology, Beijing Medical University. Beijing, China；Department of Phyarmacology, Institute of Basic Medical Science, Chinese Academy of Medical Sciences

Abstract

1.Nociception of the rat was assessed by measuring the tail flick latency (TFL)
with thermal irradiation. Drugs were administered intrathecally in serially increasing doses to observe their analgesic effect. Intrathecal injection of 100 #mu#mol of [met~(5)] enkephalin(MEK)alone produced no significant increase in TFL. However, when the subthreshold dose of MEK was administered in combination with morphine or dynorphin A-(1-13), a marked potentiation of the analgesic effect of the latter two was observed. 2.While 2.5 #mu#mol of dynorphin A-(1-13) alone produced no significant increase in TFL after its intrathecal injection, it potentiated the analgesic effect produced by serially increasing doses of morphine. 3. The methodology of serial intrathecal injections of increasing doses of drugs, as well the mutual influence of ligands specific for 3 types of opioid receptors in pain modulation are discussed.

Key words: Morphine;[met~(5)] enkephalin;Dynorphia A-(1-13);Intrathecal Injeceion;Analgeata

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Citing This Article：

Huang Long, Ren Mingfeng, Lu Junhua, Han Jisheng. Mutual potentiation of the analgesic effects of [met~(5)] enkephalin,dynorphia A-(1-13) and morphine in the spinal cord of the rat. Acta Physiol Sin 1987; 39 (5): (in Chinese with English abstract).