The Effect of Intrathecal Administration of Muscimol on Modulation of Neuropathic Pain Symptoms Resulting from Spinal Cord Injury; an Experimental Study

Introduction: Neuropathic pain can be very difficult to treat and it is one of the important medical challenging about pain treatments. Muscimol as a new agonist of gamma-Aminobutyric acid receptor type A (GABAA) have been introduced for pain management. Thus, the present study was performed to evaluate the pain alleviating effect of intrathecal injection of different doses of muscimol as GABAA receptor agonist in spinal cord injury (SCI) model of neuropathic pain. Methods: In the present experimental study male Wistar rats were treated by muscimol 0.01, 0.1 or 1 µg/10ul, intrathecally (i.t.) three weeks after induction of spinal cord injury using compression injury model. Neuropathic pain symptoms were assessed at before treatment, 15 minutes, one hour and three hours after muscimol administration. The time of peak effect and optimum dosage was assessed by repeated measures analysis of variance and analysis of covariance, respectively. Results: Muscimol with the dose of 0.01 µg in 15 minutes caused to improve the thermal hyperalgesia (df: 24, 5; F= 6.6; p<0.001), mechanical hyperalgesia (df: 24, 5; F= 7.8; p<0.001), cold allodynia (df: 24, 5; F= 6.96; p<0.001), and mechanical allodynia (df: 24, 5; F= 15.7; p<0.001). The effect of doses of 0.1 µg and 1 µg were also significant. In addition, the efficacy of different doses of muscimol didn't have difference on thermal hyperalgesia (df: 24, 5; F= 1.52; p= 0.24), mechanical hyperalgesia (df: 24, 5; F= 0.3; p= -0.75), cold allodynia (df: 24, 5; F= 0.8; p= -0.56), and mechanical allodynia (df: 24, 5; F= 1.75; p= 0.86). Conclusion: The finding of the present study revealed that using muscimol with doses of 0.01µg, 0.1µg, and 1 µg reduces the symptoms of neuropathic pain. Also the effect of GABAA agonist is short term and its effectiveness gradually decreases by time

Effect of peppermint extract on food intake and body weight following immobilization stress in mice

Introduction: Stress interferes with the different physiological performance systems and causing in some behavioral responses that including food intake. Considering the effects of peppermint in traditional medicine as an effective drug on some disorders in this study its effect on food intake and body weight following immobilization stress were studied.Materials and Methods:: Male mice were divided randomly into the three groups; the first group as a control group, second group as a stress group and third group as stress plus peppermint oil group with ten mice in each. The second group as a stress group received immobilization stress four hours for three days. Third group as stress plus peppermint oil group received stress in addition to administration of 27 mg/kg peppermint oil intraperitoneally before stress. After three days of treatment, food intake and body weight were measured. Results: Based on food intake, there were statistical differences between control and stress groups (P=0.001), stress and stress plus peppermint oil (P=0.001), control and stress plus peppermint oil (P=0.025). Based on body weight, there were statistical differences in stress and stress+ peppermint oil groups before and after experiment (P<05).Conclusion: This study showed that the level of food intake and body weight in stress group after three days compared to the control group was decreased. Administration of peppermint oil, improved food intake and weight gain after chronic stress immobilizatio