A novel pharmacological role for minocycline: attenuating the withdrawal syndrome of morphine in rat

The aim of this study was to evaluate the effect of minocycline on morphine withdrawal syndrome in male rat.

male wistar rats (225 – 275 g) were selected (n=8) randomly and divided in to six groups: In order to evaluate the effect of minocycline on morphine withdrawal syndrome. Morphine was administered subcutaneously for nine days: Day 1: 5mg/kg/12h, Day 2,3: 10 mg/kg/12h, Day 4,5: 15 mg/kh/12h, Day 6,7: 20 mg/kg/12h, Day 8,9: 25 mg/kg/12h. On ninth day only the morning dose of morphine and minocycline were injected. Minocycline was injected just before the morphine injection twice a day, on ninth day an hour after the last dose of morphine, naloxone (4 mg/kg’ ip) injected and the withdrawal signs (Jumping, Rearing, Genital Grooming, Abdomen Writhing and Wet Dog Shake) were recorded for 60 minutes. Animals received saline (1 ml/kg/12h’ ip) or {saline (1ml/kg/12h, ip) + morphine (10 mg/kg/12h, sc)} or {minocycline (10,20,40 mg/kg/12h’ip) + morphine (10 mg/kg/12h’sc)}.

Results showed that minocycline decreased withdrawal syndrome significantly (p<0.001).

minocycline decreased the withdrawal syndrome of morphine and the possible mechanism is related to inhibition of Nitric oxide / N – methyl D – aspartat pathway.