The study for analgesic effects of Magnesium

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The effects of Magnesium on the postoperative pain in human, current perception threshold (CPT) in rat, and expression of c-fos protein in the spinal cord in rat evoked by histamine injection were studied.The changes in perioperative serum ionized Magnesium were investigated in 210 patients underwent elective operations. Serum ionized Magnesium was gradually decreased during operation and postoperative period. The decrease was greater in the patients with abdominal surgery than in those with orthopedic and neurosurgical operations. In 24 women undergoing elective abdominal hysterectomy, the effects of Magnesium sulfate administration on the postoperative analgesic requirements were studied. The amount of postoperative morphine in the Magnesium administrated group was smaller than control group.Male Wistar rats were allocated to six treatment groups : Gr 1(saline), Gr 2a (Magnesium 2mmol/kg), Gr 2b (Magnesium 4mmol/kg), Gr 3(morphine 2mg/kg), Gr 4a (morphine 2mg/kg + Magnesium 2mmol/kg), Gr4b (morphine 2mg/kg +Magnesium 4mmol/kg). Although CPT at 5Hz in Gr 3, 4a, and 4b increased, there were no intergroup differences.In another study, male Wistar rats were allocated to 4 treatment groups : Gr C (saline), Gr M1 (Magnesium 30mg/kg), Gr M5 (Magnesium 150mg/kg), Gr M10 (Magnesium 300mg/kg). Each rat then received an S.C. injection of histamine into the hind paw. Sections of the lumber spinal cord were immunostained with anti c-fos antibody ; the numbers of fos-like immunoreactive cells (FLI) in every specific lamina were counted. In the sections of L3 and L4 level, the numbers of FLI labeled neurons for Gr M5 and M10 were less than Gr C and M1.These findings suggested that Magnesium could be an interest adjuvant for postoperative pain management and have effects on spinal neurons, some of which directly receive noxious inputs.