Endocrine Abstracts

Glucocorticoids modulate the effects of other hormones and also mediate cell function. Dexamethasone, in common with androgen metabolites, has been shown to increase alkaline phosphatase activity and bone specific marker proteins The aim of this investigation is to establish an androgen responsive element to dexamethasone as an index of regenerative potential in the periodontium, using the alkaline phosphatase inhibitor levamisole (L). 4 cell lines of oral periosteal fibroblasts were established in culture, using tissue isolated from periodontal patients (20-40y) requiring mucogingival surgery (obtained local Ethical Committee approval). Duplicate incubations of confluent monolayer cultures were performed in multiwell plates using 14C-testosterone or 14C-4-androstenedione as substrates in Eagle's MEM. Optimal concentrations of dexamethasone (1 and 3 micrograms/ml) were added to the incubation in the presence or absence of an inhibitory concentration of L(30microgram/ml). At the end of a 24h incubation period, the medium was solvent extracted with ethyl acetate, evaporated to dryness, solubilised in chloroform and subjected to thin layer chromatography for separation of metabolites. The separated metabolites were quantified using a radioisotope scanner. Dexamethasone caused significant stimulation of 5 alpha reductase and 17beta hydroxysteroid dehydrogenase enzyme activity, increasing the yields of DHT by 44-48% and 4-androstenedione by 35% from testosterone as substrate. L inhibited these enzyme activities by 28-30% and there was an intermediate response, with values similar to those of controls, when Dex was combined with L (n=6; p<0.01). When 4-androstenedione was used as substrate, the metabolites formed were DHT, testosterone, diols and androstanedione. Except T, other metabolites showed significant increases of 26-45% in response to Dex, 23-31% inhibition by L and intermediate responses similar to control values in response to combinations of Dex+L. All values were significant (n=6; p<0.01). Androstanedione is an important intermediary in the formation of DHT from androstenedione, by 5 alpha reduction. The result indicates that the anabolic potential of dexamethasone in stimulating biologically active androgens can be mediated by alkaline phosphatase activity.