Alleviation of Morphine Withdrawal Signs but Not Tolerance by the Essential Oil of Kelussia odoratissima Mozaff.

The aim of the present study was to assess the effects of chronic and acute treatment of the essential oil (EO) of Kelussia odoratissima Mozaff. on the development of morphine tolerance and dependence in mice. Mice were rendered tolerant to and dependent on morphine by subcutaneous injection of morphine over a period of 5 days. Tolerance was assessed using the tail-pinch test and withdrawal signs of morphine were precipitated by injecting naloxone 2 h after the final morphine injection. Repeated injection of the EO of K. odoratissima (5 and 10 mg/kg) for 4 days significantly suppressed morphine-withdrawal jumps, a sign of the development of dependence to opiate as assessed by naloxone precipitation withdrawal on day 5 of testing. A single injection (25, 50, 100 mg/kg) of the EO on day 5, 1 h prior to morphine failed to produce any significant change in morphine withdrawal signs. Neither the acute nor the chronic administration of EO of the K. odoratissima did significantly influence the development of tolerance to the analgesic effect of morphine. Alleviation in morphine signs of withdrawal after chronic injection with K. odoratissima is indicative of reversal of neuronal adaptation that takes place during morphine presence in the brain.