Antinociceptive effects of oral and intraperitoneal administration of alcoholic Datura stramonium seeds extract in male rats

The present study is a designed protocol for investigation of the analgesic effect of oral and intraperitoneal (i.p.) administration of alcoholic Datura stramonium (DS) seed extract as a rich source of alkaloid substances. Male NMRI rats were divided into control and treatment groups. The treatment rats received different doses of the DS seed extract, which was prepared from alcoholic smashed seeds. Then, the animals from each group were subjected to pain scoring experiments such as hot plate and formalin tests. The results of the experiments i.e., antinociceptive effect of DS seeds extract in i.p (5, 10, 25, 50, 100, 200 and 250 mg/kg) and oral application methods (200, 400 and 800 mg/kg) were compared with other groups, morphine sulfate and naloxone as positive and negative control groups, respectively. We found the 30 and 100 mg/kg of the extract as intraperitoneal ED50 in the hot plate and formalin tests, respectively. However, the extract over than 100 mg/kg, i.p could potentially alleviate the pain in hot plate and both phases of formalin test. Besides, there was a marked antinociceptive effect for the extract (over than 400 mg/kg) in oral method in hot plate and both phases of formalin tests. In our following experiments the effective doses of morphine sulfate as positive control test were obtained over than 15 mg/kg; i.p. and the acquired LD50 was close to 2300 mg/kg. In summary, comparing the analgesic effect of different doses of morphine sulfate with DS seed extract in i.p and oral conditions and considering to the extract LD50, we conclude that the DS seeds extract have a potent, absorbable, and nearly safe ingredient which can exert a potential analgesic effect in acute and chronic pain. Key word: Datura stramonium; Formalin test; Hot plate; Rats. Iranian Journal of Pharmaceutical Research (2004) 4: 231-236