Abstract
The effect of low dose whole-body gamma irradiation on inflammation and its possible modulation by Ginkgo biloba extract (GbE) was studied in the carrageenan-induced paw oedema model. Rats were subjected to two doses of gamma radiation (2 Gy or intermittent radiation at 2 Gy increment delivered daily up to cumulative dose of 4 Gy), 4 h before unilateral subplantar injection of carrageenan. The effect of GbE (25 or 50 mg/kg) administered subcutaneously daily for 3 days was also studied. Local oedema (days 1-3), the content of gamma glutamyl transpeptidase (GTT), malondialdehyde (MIDA) and glutathione (GSH) in paw (72 h), were determined. In rats subjected to 4 Gy fraction, paw oedema was significantly reduced 1-4 In post-carrageenan injection (-26.2 to -16.2% vs control group). Moreover, at 24, 48 and 72 h after carrageenan, paw oedema was much reduced in the 2 Gy (-33.6, -46.4, -40%) or 4 Gy (-55, -56, -71.8%) irradiated groups compared to carrageenan unirradiated control. In addition, in irradiated rats, the carrageenan oedema was further significantly reduced by the administration of GbE, the effect of the agent being more marked in those irradiated with 2 Gy fraction. Changes in paw oedema were matched by a reduction in GGT and MDA paw tissue levels, while GSH content decreased in inflamed paw tissue 72 h post-treatment. These results indicate that exposure to 4 Gy fraction decreased the carrageenan-induced paw oedema and that the administration of GbE further lessened the severity of this inflammatory response in irradiated rats. The effects observed may be related in part to the inhibition of GGT activity and MIDA production, and partly to augmentation of GSH content in the inflamed paw tissue.