ANTAGONISTIC EFFECT OF CALCIUM AND MAGNESIUM IONS IN AMYGDALA ON ELECTRO-ACUPUNCTURE ANALGESIA AND MORPHINE ANALGESIA IN THE RABBIT
1984; Linguagem: Inglês
ISSN
0001-7302
Autores Tópico(s)Healthcare and Venom Research
ResumoCalcium and magnesium ions have been reported to interact with the analgesic effect elicited by opiates and electroacupuncture (EA) stimulation. The aim of this study is to compare the effect of Ca+2 and Mg42, and to localize their sites of action.The analgesic effect of EA and morphine as assessed by radiant heat-head jerk latency was found to be reduced by 87% and 67% respectively (p 0.001) when CaCl2 was injected into bilateral amygdala (20nmol/1μl/side). Unilateral injection caused a 55% for both EA (p0.05) and morphine analgesia (p0.001). Administration of the same amount of CaCl2 into the vicinity of amygdala was ineffective (-35%, -4%, p0.05). Tntra-amygdaloid injection of MgCla (20nmol/1μl/side) elicited a similar attenuating effect on EA analgesia (-71%, p 0.001) and morphine analgesia (-73%, p0.001).Microinjection of the chelating agent CDTA (20nmol/side) into bilateral amygdala caused a marked augmentation of EA (+147 %, p 0.001) and morphine analgesia (+266%, p 0.001). A similar degree of augmentation was seen (+151%, +252%, p 0.001) with verapamil which prevent Ca+2 influx by blocking Ca+2 channels.The results indicate the importance of amygdaloid Ca+2 and Mg+2 in modulating the effect of EA and morphine analgesia, and a similarity of the mechanisms underlying the two analgesic processes.
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