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An investigation into the therapeutic effects of the medicinal herb ginkgo biloba on pain and inflammation Recent studies in vitro have suggested that the herb Gingko biloba may have anti-inflammatory properties (Ilieva et al., 2004; Ho and Lai, 2004) and modulatory effects on key pain-related signalling molecules, including cyclooxygenase-2 (Kwak et al., 2002). Gingko biloba standardised extract has also been reported to reduce paw oedema following carrageenan-induced inflammation and capsaicin-induced paw licking behaviour in the rat (Abdel-Salam et al., 2004). The aim of this study was to characterise the analgesic and/or anti-inflammatory properties of Ginkgo biloba in an animal model of acute pain and inflammation. Carrageenan (3%; 50 μl) was injected intradermally into the left hindpaw of adult male Sprague-Dawley rats (n = 6-10/group; 250-300 g) and the effects of oral administration of Gingko biloba standardised extract (EGB-761) (100 or 300 mgkg-1) or drug-vehicle delivered 0.5 or 3 h post-carrageenan on mechanical and thermal response thresholds and paw oedema measured. Mechanical response threshold (in grams) and thermal response latency (in sec) to hindpaw stimulation and paw oedema (cm3) were measured before and 2, 4, 6 and 24 h post-carrageenan. The maximum effect (Emax) was also calculated as the maximum change in threshold after carrageenan injection from baseline responses. Data (mean ± SEM) were analysed using one-way ANOVA with post-hoc Tukey’s test. Carrageenan induced a significant reduction in mechanical and thermal withdrawal threshold and paw oedema. Maximum hypersensitivity and paw oedema was observed 6 h post-carrageenan. Administration of EGB-761 (100 and 300 mgkg-1) 3 h post-carrageenan blocked thermal hypersensitivity at 6 h (Emax: 16.3 ± 4.0% and 19.3 ± 5.8% for 100 and 300 mgkg-1, respectively) compared to vehicle (Emax: 60.1 ± 6.1%) (p < 0.001). When administered 0.5 h post-carrageenan, 300 mgkg-1 E GB-761 significantly attenuated thermal hypersensitivity at 6 h (Emax: 42.6 ± 4.3%) compared to vehicle (Emax: 64.7 ± 4.7%) (p < 0.01). Administration of EGB-761 had no effect on mechanical hypersensitivity when administered at 0.5 h post-carrageenan, however when administered 3 h post-carrageenan, 300 mgkg -1EGB-761 significantly attenuated mechanical hypersensitivity at 6 h (Emax: 40.4 ± 5.4%) compared to vehicle (Emax: 60.1 ± 3.6%) (p < 0.05). EGB-761 (100 or 300 mgkg-1) had no effect on paw oedema. These results demonstrate that Ginkgo Biloba has significant analgesic activity but no anti-inflammatory properties in this model of acute inflammatory pain, suggesting that it may be a useful therapeutic agent for the treatment of pain.
Kwak, W.J. et al. (2002) Planta Medica 68, 316-21. |
