كليدواژه :
Morphine , Female Mice , alpha-adrenoceptors , Conditioned Place Preference , مورفين , ترجيح مكان شرطي شده , موش سوري ماده , گيرنده هاي آلفا - آدرنرژيك
چكيده لاتين :
Studies have shown that the noradrenergic system is involved in the analgesic effects of opioids and in the expression and development of physical signs of opioid withdrawal. The current study was designed to determine whether alpha- adrenoceptor agonists and antagonists could modify the acquisition or expression of morphine conditioned place preference (CPP) in mice. A biased CPP paradigm was used to study the effect of the agents. In a set of experiments, the drugs were used during development of CPP by morphine or were used alone in order to see whether they produce any motivational effects. In another series of experiments, the adrenergic drugs were used on the test day in order to examine whether they could change the expression of previously established CPP. Our data showed that subcutaneous (s.c) injections of morphine (0.5-8 mg/kg) induced CPP in a dose-related manner. Intraperitoneal (i.p) injections of an a 1 adrenoceptor agonist. phenylepherine (0.03-0.3 mg/kg) decreased the expression of morphine-induced CPP. However, injections of al adrenoceptor antagonist prazosin (0.01-0.1 mg/kg, i.p) did not show any effects. Administration of clonidine an alpha2 receptor agonist (0.0001-0.001 mg/kg, i.p), also reduced morphine effects and injection of alpha2 receptor antagonist yohimbine (0.005-0.05 mg/kg, i.p) was ineffective. Administration of phenylepherine (0.03-0.3 mg/kg, i.p) in combination with morphine in the conditioning days, increased acquisition of morphine CPP whereas administration of prazosin (0.01-0.1 mg/kg, i.p) decreased the morphine CPP. Administration of clonidine (0.0001-0.001 mg/kg, i.p) in the conditioning days in combination with morphine, reduced morphine CPP. The opposite effects were obtained when yohimbine (0.005-0.05 mg/kg, i.p) was used. None of the drugs were able to induce motivational effects when used alone in. It is concluded that alpha-adrenoceptor agents may influence the expression and acquisition of morphine-induced CPP.
