Background: It has been postulated that there is a probable relationship between opioid and adrenergic systems. In the present study we have evaluated the effect of morphine alone and together with clonidine (α2 agonist) and Idazoxan (α2 antagonist) on morphine dependency in rat.

Materials and methods: For this experimental study, 32 rats were divided in 4 groups of control, morphine, morphine with clonidine and morphine with idazoxan. Having anesthesized the rats with ketamine and rammpon, jugular vein was cannulated and rats were addicted with autoinjection method. All groups were evaluated with lever pressing during 2-hour stay in autoinjection chamber. Morphine dependency was evaluated by ANOVA.

Results: There was no significant difference between the active and passive lever pressing in the control rats, however, in other groups active lever pressing was significantly more than the passive pressing. Clonidine group consumed more morphine and the idozoxan group pressed lever more actively than the controls (p<0.05).

Conclusion: Clonidine decreases dependency level however idazoxan increases this dependency to morphine. Stimulatory effect of clonidine on α2 adrenergic receptors in LC nucleolus decreases the dependency to morphine, however, the inhibitory effect of idazoxan on α2 adrenergic receptors stimulate noradernaline release and increase dependency to morphine.