Pentoxifylline decreases allodynia and hyperalgesia in a rat model of neuropathic pain

Pentoxifylline [PTX] is a non-specific cytokine inhibitor that has been reported to attenuate pain in several animal models and humans. However, long-term therapeutic effects of PTX on neuropathic pain in a rat model of chronic constriction injury [CCI] are not completely clear. This study was conducted to examine the effect of long-term administration of PTX on neuropathic pain in rats. Neuropathic pain was induced by sciatic nerve ligation using of CCI model in rats. Rats were randomly assigned into sham, CCI-saline treated, and CCI-PTX treated [30 or 60 mg/kg ip] groups. PTX or saline administered at 30 min before CCI and daily for 14 days post-CCI. At the days of 3, 7, 11 and 14 following CCI, by using standard methods effects of thermal hyperalgesia, thermal and mechanical allodynia in all groups were examined using the standard methods. The CCI-saline treated group showed a significant increase in mechanical and thermal allodynia, and thermal hyperalgesia as compared with the sham group in the tested days. Administration of the higher dose of PTX [60 mg/kg/day], but not the lower dose [30 mg/kg/day] significantly reduced mechanical and thermal allodynia, as compared with the CCI-saline treated group on days of 3, 7, 11 and 14 [all P values<0.001]. Also, both doses of PTX significantly reduced thermal hyperalgesia as compared with the CCI-saline treated group on these days [all P values<0.001]. Results of this study show that chronic administration of PTX reduces the neuropathic pain in a rat model of CCI. Thus, this drug may have a therapeutic application in the treatment and management of neuropathic pain in humans

[Anxiolytic effects of the aqueous extracts of spinach leaves in mice]

Previous studies have shown the effect of antioxidant properties of spinach on delaying the aging process of CNS and age related cognitive function and some neurodegenerative diseases. This study was designed to evaluate the anxiolytic effects of different doses of aqueous extracts of spinach leaves. This study included fifty male mice [Wt: 25-30 g] which were divided into three experimental and two control groups. Different doses of the spinach extract powder [0.05, 0.10 and 0.15 g/mice] were given to the experimental groups for one month. Also, one of the control groups received water and the other one sucrose 3% [w/v] for one month. In order to increase the activity and curiosity of the mice, they were put inside a box with black walls for five minutes. Then the animals were transferred to the elevated plus maze in regular time intervals and evaluated for standard indexes of anxiety reaction for five minutes. The results of this study showed that percentage of open time was significantly increased in doses of 0.10 and 0.15, and the number of open arm entries was more with a dose of 0.15 g of spinach extract in comparison to the control group [P<0.05]. Furthermore, no significant differences were found in the total number of arm entries between the groups. In comparison to the control group, the number of SAP was significantly reduced with doses of 0.10 and 0.15 g of spinach extract in the experimental group [P<0.05]. It is concluded that higher doses of aqueous extract of spinach can decrease anxiety

Role of saphenous nerve in the behavioral responses of neuropathic pain - due to chronic constriction injury in rats

The chronic constriction injury [CCI] was introduced by Bennett and Xie in 1988 as an animal model of peripheral mononeuropathy. In this model, serious sensitivity to the thermal and mechanical allodynia and hyperalgesia is increased the areas in which sciatic nerve innervated. The spread of receptive fields of the saphenous nerve which innervates the medial part of the foot. In this study, we have examined the behavioral effects of the section of saphenous nerve at the time of applying CCI. Adult male Sprague - Dawley strain, with the weight 200 - 300 grs, used for experiments. Animals divided into four groups: sham operated, CCI group, cut of saphenous nerve [saph.] and CCI +/- saph. Two weeks after post operation, animals tested for behavioral responses: thermal allodynia [acetone blob and immersion of hind paw in 10[°C] water] thermal hyperalgesia [immersion of hind paw in 42[°C] water] mechanical allodynia [Von Frey], mechanical hyperalgesia [Pin Prick] and usage of damage paw. All symptoms of the neuropathic pains were appeared among all animals which went under CCI. CCI + Saph group showed analgesia, thermal allodynia and hyperalgesia, mechanical hyperalgesia and also usage of damage paw, except in mechanical allodynia. Results indicated that saphenous nerve may affect on behavioral responses of neuropathic pain related CCI. Saphenous nerve [as a neighboring with sciatic nerve] may affect on behavioral responses of neuropathic pain, probably by making collateral branches which may penetrate into the damage area