Ginkgo biloba extract attenuates hyperalgesia in a rat model of vincristine-induced peripheral neuropathy.

BACKGROUND: Chemotherapy-induced peripheral neuropathy is a common, dose-limiting side effect of cancer chemotherapeutic drugs. Hyperalgesia is a common component of neuropathic pain. Ginkgo biloba extract (GBE) is an oriental herbal medicine that has various pharmacological actions. In this study, we evaluated the effects of oral GBE on hyperalgesia in a rat model of vincristine-induced neuropathy. METHODS: Male Sprague-Dawley rats (200-250 g) were injected intraperitoneally with vincristine or saline (0.1 mg/kg/d) using a 5-day-on, 2-day-off schedule over 12 days. All the behavioral tests for mechanical, cold, and heat hyperalgesia were conducted before the daily injection during the course of vincristine treatment. Rats that developed hyperalgesia 14 days after vincristine injection were randomly assigned into 4 groups. Distilled water and GBE (50, 100, and 150 mg/kg) were administered, respectively, to the individual groups. We examined the hyperalgesia at preadministration and at 15, 30, 60, 90, 120, 150, and 180 minutes after oral drug administration. RESULTS: Saline injection did not have any significant effect on mechanical, cold, and heat hyperalgesia. Vincristine injection produced mechanical and cold hyperalgesia. For the GBE groups, the paw withdrawal threshold to mechanical stimuli was significantly increased and withdrawal frequency to cold stimuli was significantly reduced versus the control group dose-dependently (P < 0.05). CONCLUSIONS: This study demonstrates that oral administration of GBE is associated with a dose-dependent antihyperalgesic effect on mechanical and cold stimuli in a rat model of vincristine-induced neuropathy.

Pain-related anxiety as a mediator of the effects of mindfulness on physical and psychosocial functioning in chronic pain patients in Korea.

UNLABELLED: Mindfulness involves reducing potential influences from aversive cognitions, sensations, and emotions on behavior. Mindfulness may influence the experience of pain-related anxiety, and thereby enhance other aspects of physical and psychosocial functioning. Thus, the purpose of this study was to investigate a potential mediating role of pain-related anxiety between mindfulness and physical and psychosocial functioning in chronic pain patients. This cross-sectional/correlational study used archival data (N = 226) obtained from the larger Korean Pain Study at a university-based pain-management center in Korea. Based on the inclusion criterion for the present study, archival data were analyzed for a final sample of 179 patients with chronic pain. Structural equation analyses showed that both the partial- and full-mediation models had adequate goodness-of-fit indices for physical and psychosocial functioning. Subsequent chi-square tests, however, indicated that the more parsimonious full-mediation model was preferred to the partial-mediation model for physical and psychosocial functioning. Bootstrapping procedures yielded significant mediation effects of pain-related anxiety in the full-mediation models on physical and psychosocial functioning. These findings suggest that being mindful may lead indirectly to a decrease in the disabling influences of pain-related anxiety, thereby contributing to better physical and psychosocial functioning, rather than playing a direct contributing role for better functioning among chronic pain patients in Korea. PERSPECTIVE: This article examines the mediating role of pain-related anxiety between mindfulness and physical/psychosocial functioning. Results suggest that mindfulness methods may benefit patients having pain-related anxiety and consequent disability. These benefits may derive from the way processes of mindfulness interact with processes of avoidance and with cognitive influences on emotional suffering.

The effects of Ginkgo biloba extract EGb 761 on mechanical and cold allodynia in a rat model of neuropathic pain.

BACKGROUND: Neuropathic pain is chronic pain that is caused by an injury to the peripheral or central nervous system. The symptoms of neuropathic pain are continuing pain, hyperalgesia, and allodynia. Ginkgo biloba extract is an oriental herbal medicine that has various pharmacological actions. We examined the effect of Ginkgo biloba extract, EGb 761, on the mechanical and cold allodynia in a rat model of neuropathic pain. METHODS: Male Sprague-Dawley rats were prepared by tightly ligating the left L5 and L6 spinal nerves. All the rats developed mechanical and cold allodynia 7 days after surgery. Fifty neuropathic rats were assigned into five groups for the intraperitoneal administration of drugs. The study was double-blind and the order of the treatments was randomized. Normal saline and EGb 761 (50, 100, 150, and 200 mg/kg) were administered, respectively, to the individual groups. We examined mechanical and cold allodynia at preadministration and at 15, 30, 60, 90, 120, 150, and 180 min after intraperitoneal drug administration. Mechanical allodynia was quantified by measuring the paw withdrawal threshold to stimuli with von Frey filaments of 1.0, 1.4, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, 15.0, and 26.0 g. Cold allodynia was quantified by measuring the frequency of foot lift with applying 100% acetone. We measured the locomotor function of the neuropathic rats by using the rotarod test to reveal if EGb 761 has side effects, such as sedation or reduced motor coordination. RESULTS: The control group showed no differences for mechanical and cold allodynia. For the EGb 761 groups, the paw withdrawal thresholds to mechanical stimuli and withdrawal frequencies to cold stimuli were significantly reduced versus the preadministration values and versus the control group. The duration of antiallodynic effects increased in a dose-dependent fashion, and these were maintained for 120 min at the highest dose (P < 0.05). Only at the highest dose (200 mg/kg) did EGb 761 reduce the rotarod performance time. CONCLUSION: We conclude that Ginkgo biloba extract, EGb 761, attenuates mechanical and cold allodynia in a rat model of neuropathic pain, and it may be useful for the management of neuropathic pain.

Motor cortex stimulation in a patient with intractable complex regional pain syndrome type II with hemibody involvement. Case report.

The authors describe the effectiveness of motor cortex stimulation (MCS) in a patient with complex regional pain syndrome (CRPS) Type II, formerly known as causalgia, with hemibody allodynia. During MCS, a subjective sensation of warm paresthesia developed in the painful hand and forearm and spread toward the trunk. Pain and allodynia in the areas associated with this sensation were alleviated significantly. The analgesic effect of stimulation proved to be long lasting and was still present at the 12-month follow up. The authors speculate that MCS might exert its effect through the modulation of thalamic activity in this particular case of CRPS with hemisensory deficit. A central mechanism associated with functional disturbance in noxious-event processing in the thalamus might have an important role in the pathogenesis of the condition.