Resumen de Anabolic Potential of Fibroblasts from Chronically Inflamed Gingivae Grown in a Hyperglycemic Culture Medium in the Presence or Absence of Insulin and Nicotine
Background: Impaired fibroblast function due to hyperglycemia shows reversal in response to insulin. The aim of this investigation was to use a hyperglycemic cell-culture model to study the anabolic products of androgen metabolism in fibroblasts in response to insulin and nicotine.
Methods: Human gingival fibroblasts were derived from chronically inflamed gingivae of six nondiabetic periodontal patients with no history of smoking. Six cell lines were established in monolayer culture in 24 well multiwell plates, and duplicate incubations were performed with each cell line for all three experiments. Eagle's minimum essential medium was used in a range of individual experiments, with radiolabeled testosterone as substrate, in the presence or absence of (1) glucose (1 to 4,000 µg/ml); (2) insulin (1 to 100 µg/ml) independently; (3) an effective concentration of glucose (500 µg/ml) with serial concentrations of insulin (1 to 100 µg/ml); and (4) effective concentrations of nicotine (250 µg/ml), glucose, and their combinations in response to insulin (5 µg/ml). The controls contained no agents other than the radiolabeled substrate. At the end of a 24-hour incubation period, the medium was solvent extracted with ethyl acetate, and androgen metabolites were separated by thinlayer chromatography and were quantified using a radioisotope scanner.
Results: The androgen substrate 14C-testosterone was metabolized mainly to 5α-dihydrotestosterone (DHT) and 4-androstenedione. (1) Glucose at a concentration of 500 µg/ml reduced yields of DHT by 36% (n = 6; P <0.01). (2) Insulin caused a small but significant inhibition of DHT in normoglycemic cells. (3) Serial concentrations of insulin significantly counteracted the inhibitory effects of glucose on the yields of DHT (n = 6; P <0.01). (4) The independent inhibitory effects of nicotine and glucose on metabolic yields of DHT were marginally more pronounced in combination but significantly overcome in the presence of insulin.
Conclusion: Human gingival fibroblasts obtained from chronically inflamed tissue of nondiabetic patients demonstrated that the inhibitory effects of glucose and nicotine on androgen metabolism can be overcome by insulin, in varying degrees.
