en نقش گیرنده های آلفا آدرنرژیک مرکزی در بی دردی ناشی از تجویز ایمی پرامین با استفاده از آزمون فرمالین در موش صحرایی Nervous system (others) Others Experimental research article Experimental research article In this study, the effect of α-adrenoceptor agents on imipramine-induced antinociception was investigated using formalin test. Intraperitoneal (i.p.) administration of imipramine at different doses (10-80 mg/kg) induced antinociception in both phases of formalin test. In addition, intracerebroventricular (i.c.v.) injection of imipramine (1, 5, and 10 µg/rat) did not elicit any effect, although i.c.v. injection of clonidine, an α2-adrenoceptor agonist at doses of 0.05-0.8 µg/rat also elicited antinociception in both phases of the test. Furthermore, clonidine increases the antinociception induced by imipramine and yohimbine, an α2-adrenoceptor antagonist at a dose of 2 µg/rat (i.c.v.) reduced the response to imipramine at a low dose (10 mg/kg, i.p.) and clonidine (0.05 µg/rat, i.c.v.), but did not alter the response induced by higher doses of imipramine (20 and 40 mg/kg) alone or in combination with clonidine. Yohimbine by itself elicited no response. Meanwhile, phenylephrine (0.07-1.5 µg/rat, i.c.v.), an αl-adrenoceptor agonist induced antinociception in both phases of formalin test, but did not alter the imipramine-induced antinociception. The αl -adrenoceptor antagonist, prazocin neither elicited antinociception nor altered the imipramine response. Yohimbine (2 µg/rat, i.c.v.) in combination with prazocin (0.5 µg/rat, i.c.v.) further inhibited the response for imipramine alone or in combination with clonidine. Taken together, it is concluded that α2-adrenoceptor-mediated mechanism might be involved in the development of imipramine-induced antinociception. α-adrenoceptor; Imipramine; Formalin Test 131 144 http://ppj.phypha.ir/browse.php?a_code=A-10-73-111&slc_lang=en&sid=1 Mousa Sahebgharani 3200319475328460011640 3200319475328460011640 Yes Dept. Pharmacology, School of Medicine, Tehran Univ. Med. Sci., Tehran, Iran Mohammad Reza Zarrindast 3200319475328460011641 3200319475328460011641 No Morteza Samini 3200319475328460011642 3200319475328460011642 No