Methods: Confluent monolayer cultures of MG63 osteoblasts were established in MEM and incubated with pre-determined optimal concentrations of CRP (10microgram/ml), glucose oxidized LDL (G1000 LDL50microgram/ml) and minocycline (25microgram/ml), alone and in combinations of CRP+GLDL and CRP+GLDL+M; using 14C-testosterone as substrate. Each incubation was performed in 8 replicates for comparison with controls in the absence of agents. At the end of a 24h incubation period, the eluent was extracted with 2ml ethyl acetate (x 2), evaporated, solubilised in chloroform and subjected to TLC in a benzene acetone solvent system 4:1 v/v, for the separation of formed metabolites. The separated metabolites were quantified using a radioisotope scanner.
Results: The substrate 14C-testosterone was metabolized to DHT, diol and 14C-4-androstenedione via the 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase pathways respectively. Yields of DHT are shown here. There were 2-fold, 2.5-fold and 2.8-fold reductions in yields of DHT in response to CRP, GLDL and CRP+GLDL respectively when compared with control incubations (n=8; p<0.001). There was a 22% increase in the yield of DHT in response to M alone when compared with control incubations; and the combination of CRP+GLDL+M resulted in restoration of yields of DHT to those of control values (n=8;p<0.001).
Conclusion: Using the antioxidant marker DHT, the oxidative effects of CRP and GLDL were overcome by minocycline. Adjunctive use of minocycline in the management of periodontitis could benefit comorbidities, by reducing inflammatory loading.