Antioxidant effects of glutathione and IGF in a hyperglycaemic cell culture model of fibroblasts: some actions of advanced glycaemic end products (AGE) and nicotine.

The aim of this investigation was to establish potential oxidative effects of glucose, advanced glycation end products (AGE) and nicotine (N) in a fibroblast cell culture model using the anti-oxidants glutathione (G) and insulin like growth factor (IGF). Assays of androgen metabolites were used as biomarkers of healing in this context. Confluent monolayer cultures of human gingival fibroblasts were established in 24 well multiwell plates and incubated in Eagle's MEM for 24h using two radiolabelled androgen substrates 14C-testosterone/14C-4-androstenedione. The established effective concentrations of G1000, glutathione and AGE were used alone and in combination with nicotine and insulin-like growth factor. The medium was then solvent extracted for steroid metabolites, evaporated to dryness and subjected to thin layer chromatography in a benzene acetone solvent system 4:1 v/v for separation of formed metabolites. The metabolites were quantified, using a radioisotope scanner. Significant reduction in the yields of DHT in response to G1000, AGE and nicotine (n=6; p <0.003) were overcome by glutathione (n=6; p <0.002). The stimulatory effect of IGF when combined with AGE was further enhanced by the antioxidant effect of glutathione (n=6; p <0.003). Glucose, AGE and nicotine had a significant inhibitory effect on the yields of the androgen biomarker DHT, overcome by the antioxidant glutathione and IGF, suggestive of an oxidant role for the former agents and an anti-oxidant one for the latter. These agents affected yields of androgen metabolites, biomarkers of oxidative stress and repair, with potential implications on healing in uncontrolled diabetic smokers.