Journal of Rafsanjan University of Medical Sciences

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Background and Objective: 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.
Materials and Methods: In this experimental stady, 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 & 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.
Results: 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.
Conclusions: 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.
Key words: Pain, Formalin Test, HOPS, Morphine

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  Background and Objectives : Acute and chronic stress induces hormonal and neuronal changes which affect both pain threshold and nociceptive behaviors. But the effect of acute and chronic immobilization stress on formalin induced nociceptive behaviors are unknown. Therefore, this study evaluated the effects of acute and chronic immobilization stress formalin test on the male rat.

  Material and Methods: In this study, the formalin test (50 μL, 2%) was used to evaluate the effects of acute restraint stress on nociceptive responses. Animals (42) were initially submitted to one session of acute restraint stress (15, 30, 60 min) or chronic restraint stress (10 and 20 days, each day 30 min) and immediately submitted to the formalin injection in hind paw to evaluate nociceptive behaviors.

  Results: Acute 60 minutes exposure to restraint stress did not reduce the nociceptive behaviors by chemical stimulation (formalin 2%) of the rats, while 15 minutes exposure to restraint stress reduced formalin induced nociceptive behaviors in phase 2, and 30 minutes exposure to restraint stress reduced formalin induced nociceptive behaviors in phase 1, interphase and phase 2. Chronic restraint stress for 10 and 20 days (each day 30 min) did not increase the stress induced analgesia. These findings suggest that acute exposure to restraint for 30 minutes produce greater decrease in nociceptive behaviors than 15 and 60 minutes.

  Conclusion: Acute restraint stress can produce short-term and long-term SIA (Stress Induced Analgesia) for tonic pain. The short-term SIA is reflected as a decreasing in nociceptive behaviors during phase 1, whereas the long-term SIA is reflected as a decrease in nociceptive behaviors during phase 2.

  Key words: Formalin test, Restraint stress, Rat

  

  Funding: This research was funded by Qazvin University of Medical Sciences.

  Conflict of interest: None declared

  Ethical approved: The Ethics Committee of Qazvin University of Medical Sciences approved the study.

  

  How to cite this article : Heidari Oranjaghi N, Ghasemi E, Mahdipour H, Salehi B, Sofiabadi M, Erami E, Azhdari Zarmehri H . Effects of acute and chronic immobilization stress on formalin test in the male rat . J Rafsanjan Univ Med Scie 2012 11(4): 391-402. [Farsi]

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Background and Objective: Some studies have shown that different exercises reduce pain in different levels by affecting the levels of opioid. Therefore, we investigated the effect of exercise on pain and morphine-induced analgesia in the formalin test in male mice.

Materials and Methods: In this experimental study, 120 mice were randomly divided into 8 groups according to three different training sessions and uae of  received morphine or saline. The training program was conducted on a treadmill for 30 minutes on the speed of 0.3 meters per second with different slopes. Thirty minutes before starting each exercise, 5 mg of morphine per kg of the animal weight was injected intraperitoneally. Finally, all groups were tested using the formalin test. Data were analyzed using one-way ANOVA and post hoc Tukey test.

Results: A significant reduction was found in response to painful stimuli in the acute phase (0-5 minutes) among the morphine receiving groups (p=0.001). On the other hand, the response to painful stimuli in the chronic pain phase (16-60 min) showed a signification reduction for the morphine receiving groups as well as the exercise group with a positive slope (p=0.015). 

Conclusion: If the intensity of exercise can reach the threshold level required to stimulate the endogenous opioids, it is likely to reduce the feeling of pain. Furthermore, the effect of morphine can not be influenced by the kind of exercise.

Key words: Acute pain, Chronic pain, Exercise, Formalin test, Morphine

 

Funding: This research was funded by Shiraz University.

Conflict of interest: None declared.

Ethical Approval: The Ethics Committee of Shiraz University of Medical Sciences approved the study.

 

How to cite this article: Jafari H, Daryanoosh F, Zarifkar A, Ghiasi E, Mohammadi M. The Relationship between Job Effect of Exercise on Pain and Morphine-Induced Analgesia in the Formalin Test in Male Mice, 2013. J Rafsanjan Univ Med Sci 2014 13(2): 97-108 [Farsi]