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jia tu zuo he he dao shui guan zhou wei hui zhi nei wei liang zhu she lv hua gai zuo kang dian zhen he ma fei de zhen tong zuo yong
Author(s): 
Pages: 463-470
Year: Issue:  5
Journal: Acta Physiologica Sinica

Keyword:  habenulaperiaqueductal graycalcium chlorideelectroacupuncturemorphineanalgesia;
Abstract: Rabbits equipped with bilateral intracranial cannulae directed to habenulaor periaqueductal gray(PAG)were given microinjection of CaCl_2 solution at a doseof 15—20 nmol/1μl/site to be finished within 8 min.Pain threshold was measuredby the latency of avoidance response(head jerk)elicited by radiant heat exposurebefore and after intracerebral injection.Microinjection of CaCl_2 produced nosignificant effect on the basal pain threshold.However,the analgesic effect elicitedby electroacupuncture(EA)or morphine(2 mg/kg,iv)was found to be significantlyreduced by more than 50% in rabbits given CaCl_2 to bilateral PAG or habenulanuclei.No significant effect was shown when the same dose of CaCl_2 was admi-nistered into tile vicinity of the nuclei,implying a high specificity for the site ofaction.Injection of CaCl_2 into bilateral habenula was more effective than uni-lateral injection,although in PAG area unilateral injection was sufficient to producea maximal effect.Intra-PAG injection of CaCl_2 was significantly more effectivein blocking EA analgesia(—86%)than blocking morphine analgesia(—54%).The results are in line with the hypothesis that the ability of morphine andendogenously released opioid peptides in blocking neuronal Ca~(2+)influx in certainCNS structures including PAG and habenula may constitute the basic mechanismunderlying morphine analgesia and EA analgesia.
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