سینا پوزش

The application of herbal plants instead of synthetic drugs is increasing in recent years because of their lower side-effects and high varieties of efficient components. The aim of the present study was to evaluate the antinociceptive effects of hydroalcholic extract of grape seed using hot plate and formalin test. This experimental study has been done on 56 NMRI male mice (28±3 g) (n = 7 in each group) in weight. The hot plate and formalin test were used for acute and chronic pain. After preparation of extract، to evaluate the effect of pain related behaviors on antinociception، animals systemically received grape seed extract (75، 150، 300، mg/kg) and after 30 min pain related behaviour was monitored in formalin and for hotplate tests. The data was analyzed using SPSS software and ANOVA at significance level p < 0/05. The results showed that hydroalcholic Grape seed extract (75، 150، 300، mg/kg)، significantly can induce antinociception in both phases of formalin test. Also، the Grape seed extract caused delay in painful behaviours (licking and jumping) in hot-plate test. The present results show that hydroalcoholic extract of grape seed has analgesic properties in response to acute and chronic pain in the formalin with hot plate tests and can be substituted for chemical analgesic drugs.

The use of medicinal plants due to their lower side effects and the various efficient components has been increased in recent years. The aim of this study was to evaluate the antinociceptive effect of hydroalcoholic extract of green tea in male mice using the hot plate and formalin tests. In this experimental study، 56 NMRI male mice (weight، 28±3 g) were assigned to the control and experimental groups. The experimental group received the green tea extract (75، 150 and 300 mg/kg) and 30 min after the injection، the hot plate and formalin tests were used to assess the acute and chronic pain. Results showed that hydroalcoholic extract of green tea (75mg/kg) could induce antinociception in phase 2، not in phase 1 and interphase of the formalin test. Hydroalcoholic extract of green tea (150 and 300 mg/kg) could also induce antinociception in phase 1، interphase and phase 2 of the formalin test. Moreover، hydroalcoholic extract of green tea caused a delay on the painful behaviors in hot-plate test. Hydroalcoholic extract of green tea has analgesic properties and can be used as a substitute for chemical analgesic drugs.

There have been many studies done to recognize the mechanism of controllingpain. However, there are still a lot of un-answered questions about initiatory nervous centers in expressing nociceptive behaviors and pain modulation. The nuclei ofparagigantocellularislateralis (LPGi) participate in different functions like adjustment of blood circulation, withdrawal syndrome, and pain perception. In this study, we investigated the effect of transient inactivation of the LPGi nucleus on formalin-induced nociceptive behaviors as a tonic pain model, and also the hot plate test as an acute pain model in rats. A total of 30 adult male Wistar rats (200-250 g) were used in the study. The formalin test (50 μl, 2%) was used to evaluate the effects of temporary inactivation by lidocaine into the LPGi nucleus on formalin-induced nociceptive behaviors and hot plate test (adjusted in 52+0.1 centigrade). Animals were divided into four groups: control, sham, vehicle, treatment for the formalin test, and vehicle plus treatment for the hot-plate test. A week after the surgery, saline and lidocaine were injected into the LPGi, and the nociceptive behaviors for the formalin test and hot plate were recorded. For analysis of the data, we used t-test and ANOVA followed by theTukey post hoc test. Lidocaine injection decreased nociceptive behaviors in phase 1, interphase, and the first part of phase 2 in the formalin test compared to the saline group. Also, in the hot plate test, lidocaine injection into the LPGinuclei caused a significant increase in the noxious response compared to the saline group in the minutes 30 and 60. Our results suggest the probability of involvement of the LPGi nucleus incausing formalin induced nociceptive behaviors and also acute pain.

Stress have bidirectional effects on pain threshold and behaviours. Whereas acute stress often results in analgesia، chronic stress can trigger hyperalgesia/allodynia. The formalin test as an inflammation model، consist of three phases and the effects of repeated forced swim stress with different session numbers on these phases have not been investigated. Therefore، in this study the effects of chronic forced swim stress with different intensities evaluated in formalin test were performed in adult male Wistar rats. In this study، the formalin test (50 μL، 2%) was used to evaluate the effects of repeated swim stress with different duration and sessions on nociceptive responses. Animals were initially submitted to 6 minutes in day with different sessions (3، 5 and 10 days) of forced swim stress and after 24 hours of the last session، animals were submitted to formalin injection in hind paw to evaluate nociceptive behaviours. Exposing animals to 3 days for 6 minutes had an increasing effect on formalin-induced pain behavior only in the final stage of phase 2. This data showed that increase session number of stress have same effect on nociceptive behaviours in termination of phase 2. Moreover increasing exposure to forced swim stress for 5 and 10 sessions effected nociceptive behaviours in interphase. These findings suggest that increase sessions of chronic forced swim stress (3،5 and 10 days) effect on the nociceptive behaviours and significantly increase interphase of the Formalin Test. which could be related to modulating mechanism during this phase