RESUMEN
HOPS is a medicinal herb named Humulus, wildly grown in Europe, Asia and North America since ancient times. The antianxiety, analgesic and hypnotic effects of HOPS have been already shown in drug pharmacopoeias. HOPS consists of protein, amino acid. lipid, glucose, wax and some esterogenic components. The aim of this study was to compare analgesic effect of this herb with morphine. In this experimental study, after preparation of watery extract of HOPS by steam method, its analgesic effect was examined on mice by useing doses of formalin test and compareing it with 1 and 0.5mg/kg doses of morphine. Injection of formalin leads to a biphasic pain response in which the phasic pain period is followed by a retarded and tonic pain period. The results showed that while HOPS at dose of 8 mg/kg had no effect on the first phase, it was effective in the late phase of formalin-induced pain during 15-60 minute. This analgesic effect lies within the 0.5-1mg/kg doses of morphine but showed no significant difference with these doses of morphine. Evidences suggest that different mechanisms are involved in pain relief. Due to the presence of estrogenic compounds in HOPS extract and its suppressing effects on pain and inflammation, it can be concluded that estrogen and the inhibitory mechanism of cyclo oxigenase possibly produce these effects