A comparison of acute pain thresholds between the male and female and the effect of alcoholic Datura Stramonium seed extract

ABSTRACT Background and Objective: Opposite observations about the discrepancy in the pain perception between male and female has been reported. In this regard, pain thresholds among male and female rats in different phases of oestrous cycle were evaluated via tail immersion test. In addition, efficiency of alcoholic extract of Datura stramonium as an analgesic plant in the modulation of acute pain threshold has been studied. Materials and Methods: The control groups of male and female rats were exposed to the tail immersion test using 52?C water. In the experimental group, the extract of Datura stramonium was injected intraperitoneally 25-30 minutes before the tail immersion test. Afterwards, in both control and experimental female rats the vaginal smear samples were taken. Results: In the female rats in proestrous and dioestrous phases, the pain thresh-olds are significantly lower than that of rats in oestrous phase (p < 0.01). Also, male rats in addition to having lower pain threshold relative to whole females (p < 0.05) (the average of 4 phases) treated with Datura stramonium, show a pain threshold that is significantly lower than that of females of oestrous and metoestrous phases (p < 0.001). Furthermore, proestrous and dioestrous groups with lower pain thresholds relative to rats in oestrous and metoestrous phases show significant differences (p < 0.001). Conclusion: The female rats in the different phases of oestrous cycle have different pain thresholds and the extract of Datura stramonium is more efficient in the pain relief of female (especially oestrous stage) than that of male rats.