Endocrine Abstracts

The aim of this investigation is to study androgen metabolism in human gingival fibroblasts exposed to a hyperglycaemic environment and their response to insulin, the antagonist glucagon and nicotine; this may be extrapolated to their metabolic responses in vivo, in uncontrolled diabetes (obtained local Ethical Committee approval). Duplicate incubations of four cell lines of monolayer cultures of fibroblasts were performed in Eagle's MEM with radiolabelled testosterone as substrate; in the presence or absence of a) glucose (1-100micrograms/ml) / insulin, (3micrograms/ml) b) the insulin antagonist glucagon (0.5-10micrograms/ml) / insulin (3micrograms/ml) and c) insulin (0.5-50micrograms/ml) / nicotine (250micrograms/ml), alone and in the above combinations. The controls contained no agents, other than the substrate. At the end of a 24h incubation period, the medium was solvent extracted, separated by thin layer chromatography and quantified using a radioisotope scanner. The androgen substrate 14C-testosterone was metabolised mainly to 5alpha dihydrotestosterone (DHT) and 4-androstenedione (4-A). a) In a normo-glycaemic environment, using healthy cell-lines, insulin (I) alone reduced the yields of DHT and 4-A from 14C-testosterone by 26% and 38% respectively, compared with controls, while glucose reduced the metabolic yields of DHT and 4-A, by 75% and 25% at higher concentrations. When (I) was combined with serial concentrations of glucose, the yields of these metabolites increased to values similar to those of controls (n=4; p<0.01). b) In normo-glycaemic cells, glucagon caused 20% and 43% decreases in the yields of DHT and 4-A compared with controls, while (I) reduced these yields by 14% and 50%; in combination, the values were similar to those of controls (n=4; p<0.01). c) Nicotine caused 4.3- and 2.8-fold reduction in DHT and 4-A, while in the combined incubations with (I), there was a 53% increase in the yield of DHT (n=4; p<0.01). Insulin was able to overcome hyperglycaemic effects in this model, demonstrated by the yields of androgen metabolites, which can be used as a parameter of risk for wound healing in diabetics.