TY - JOUR JF - sjimu JO - J. Ilam Uni. Med. Sci. VL - 21 IS - 5 PY - 2013 Y1 - 2013/10/01 TI - Effect of Melatonin on the Formalin-Induced Pain in White Male Rats TT - اثر ملاتونین بر درد ناشی از فرمالین در موش های سفید صحرایی نر N2 - Introduction: Melatonin is the main prod-uct of pineal gland that has been associated with body's physiologic rhythms. New evidence suggests that melatonin plays a role in pain system. For example, the per-ipheral co-administration of melatonin and morphine produce additive analgesic effect. The purpose of this study was to evaluate the effect of central injection of melatonin on the formalin-induced pain in white male rats. Materials & Methods: In this study, 40 NMRI white rats were divided into four equal groups (each group=10 rats) inclu-ding: control, sham (having canola without melatonin injection) and 2 melatonin group that received melatonin 0.5 and 0.1µg /kg, respectively. The canola was implemented in the right brain ventricle of the rats via sterotaxic method. After 7 days of resting and then returning to normal condition, first dose of melatonin was injected and a half hour after it 50 microliter formalin (2.5 %) was injected at the floor of right foot to evaluate the acute and chronic pain. Data acquisitions were done through counting the number of licking the injected foot and accumulation of dorsal area skin (flinching) for 1 hour. Then, the acquired data were statistically analyzed. Findings: Administration of melatonin at the acute phase, reduced licking of the inje-cted site in both treatment groups compared to the control group (P SP - 73 EP - 78 AU - ghaibi, n AU - sofiabadi, m AU - rasol pour, h AU - dehghan nezhad, s AD - KW - melatonin KW - formalin test KW - rats KW - br-ain ventricle UR - http://sjimu.medilam.ac.ir/article-1-1299-en.html ER -