A Comparison of Acute Pain Threshold between the Male and Female and the Effect of Alcoholic Extract of Datura Stramonium on it

  Background: Opposite observations about the discrepancy in the pain perception between male and female has been reported. In this regard, in this research pain thresholds among male and female rats in different phases of oestrous cycle were evaluated via tail immersion test. In addition, the efficiency of alcoholic seed extract of Datura stramonium in the modulation of acute pain threshold has been studied.   Materials & Methods : T he 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 intraperituneally 25-30 minutes before the tail immersion test. Afterwards, in the both of control and experimental groups the smear samples were taken from the females.   Results: In the control group there is no significant difference in the pain threshold between male rats and females of different phases of oestrous cycle. However, in the female rats in proestrous and dioestrous phases, the pain thresholds are significantly lower than that of rats in oestrous phase (p < 0.01). In the experimental group, 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 rats than male, especially oestrous phase.