| Summary: | 碩士 === 高雄醫學大學 === 醫學研究所 === 88 === Morphine , a naturally occurring alkaloid present in the poppy plant Papaver somniferum ,is a potent analgesics that widely used in the clinical management of severe acute and chronic pain. In our study, morphine-induced antinociceptive action was determined in rodents by using the tail-flick and Writhing syndrome tests. We administrate mouse ( 20-25 g ) subcutanously with morphine, at dosage 0.01- 0.2 mg/kg , and waited for a peroid of 30 min. The mouse were assessed by the tail-flick latencies.
Compared with normal mouse, the analgesic effect of morphine was potent and shown as a dose-dependent maner. In Writhing syndrome observation, acetic acid ( 0.1 %) was injected intraperitoneally to mouse which were treated with or without morphine ( 0.01-1.0 mg/kg s.c.). The results have shown that morphine significantly decline acetic acid- stimulated Writhing syndrome frequency.
Currently, we found the different concentration of morphine ( 0.01-10 M) possessed various modulation on intracellular calcium , inositol 1,4,5-trisphosphate ( IP3) , c-AMP and c-GMP level.
In order to monitor the changes of intracellular calcium levels or images in rat C6 glioma cells, acetoxymethyl esters (AM) drivatives of fluorescent high-affinity probes, such as fura-2 and fluo-3,were used in our experiment. The calcium signaling was measured in fura-2-loaded ( 10 M ) cells on coverslips by dual-wavelength spectrofluorometry and in Fluo-3-loaded ( 5 M ) cells by ACAS 570 laser cytometer.
Ionomycin ( 1 M ), a calcium ionophor, significantly stimulating the intracellular calcium level increases by stimulating Ca2+ influx via a store-dependent mechanism. Application of the morphine ( 0.01-10 M ) attenuated ionomycin-evoked intracellular calcium levels in a dose-dependent manner in rat C6 glioma cells. However, It is intresting that morphine (10-100 M) caused the fluo-3 fluroscence intensity of intracellular Ca2+ image to elevate that peaked at 40 s and returned to basal within 3-4 min. According to this results, the radioimmunoassay (RIA) method was used to measure the content of IP3 in morphine-treated C6 cells. The intracellular IP3 are promoted gently at 5 min exposure but inhibited afetr 10 min exposure. The data indicated that IP3 indeed play a critical role in the effect of morphine on intracellular Ca2+.
There were obviously changes in intracellular c-AMP levels of rat C6 glioma cells After the incubation with morphine for 10 min. The morphine inhibit the level of intracellular c-AMP both forskolin treatment and intracellular total accumulation.
When C6 cells were incubated with morphine for 10 min, the intracellular c-GMP levels were accumulated in a dose-dependent manner. The NO donor S-nitrosoglutathione (GSNO) also sinduced intracellular c-GMP formation was reported through the effect to activated intracellular soluble guanylate cyclase. However , morphine inhibited both GSNO-induced intracellular c-GMP concentrations and total intracellular accumulation of C6 glioma cells.
According to our data, we suggest that the pharmacological effects of morphine may be through the modulation of intracellular calcium , IP3 signal or part through the regulation of intracellular c-AMP and c-GMP level.
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