脳下垂体除去による発声法で検した針鎮痛の消失
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概要
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In our previous studies, it was found that hypophysectomy in rats abolished acupuncture analgesia (AA) measured by tail-flick latency. However, Fu et al. reported that hypophysectomy did not abolish AA measured by the phenylquinone-induced writhing test. In the present experiment, the measurement of the effect of hypophysectomy on AA was taken by another method, vocalization. The threshold for vocalization was measured by applied electric current to the tail through 2 inserted electrodes. After hypophysectomy, the pain threshold measured by vocalization was extremely reduced, to about half the value of the control. Under these conditions, AA and intraperitoneal morphine (0.5 mg/kg) analgesia (MA), which has similar analgesic effects as AA were completely abolished. Close correlation in the AA and MA time course was observed between the tail-flick test and the vocalization test. Stimulation of the arcuate nucleus caused analgesia during the stimulation period, while analgesia caused by stimulation of the dorsal periaqueduct central gray, which is identified as an acupuncture afferent pathway, was long-lasting after cessation of stimulation. Since analgesia caused by stimulation of acupuncture afferent pathway was limited during stimulation, the arcuate nucleus might be involved in the descending analgesia inhibitory system. It was reported that hyperalgesia in vocalization and unchanged pain threshold in the tail-flick test were induced by lesion of the arcuate nucleus. This result is quite similar to that found after hypophysectomy in the present experiment. Therefore, results suggest that some substance liberated from the hypophysis by activation of analgesia afferent pathway might activate the arcuate nucleus to induce analgesia.
- 学校法人 昭和大学・昭和医学会の論文