Effects of alkaline phosphatase and its inhibitor levamisole on the modulation of androgen metabolism by nicotine and minocycline in human gingival and oral periosteal fibroblasts.
The aim of this investigation was to establish the implications of nicotine, minocycline, alkaline phosphatase (AP) and its inhibitor levamisole (L) on tissue turnover in human gingival and periosteal fibroblasts (HGF, HPF) using [14C]-testosterone as substrate. Monolayer cultures of HGF and HPF established from four patients were incubated in duplicate with serial and optimal concentrations of nicotine and minocycline, alone and in combination, for 24h in Eagle's MEM, with the substrate [14C]-testosterone. Further experiments were carried out on HPF only, to investigate the effects of alkaline phosphatase (AP) and its inhibitor levamisole (L) on the metabolism of [14C]-testosterone, followed by the effects of L on the modulatory actions of nicotine. The cell-conditioned medium was then solvent-extracted, analysed and quantified for steroid metabolites using a radioisotope scanner. At low concentrations, nicotine stimulated the synthesis of the physiologically active androgen 5alpha-dihydrotestosterone (DHT) from [14C]-testosterone, with inhibition at higher concentrations (n=4; P<0.01). Minocycline stimulated the synthesis of DHT, with decreased yields in the presence of nicotine (n=4; P<0.01), but greater than with nicotine alone. Alkaline phosphatase significantly enhanced the synthesis of androgen metabolites by HPF (n=4; P<0.01), with inhibition in response to L alone and in combination with AP, to less than control values (n=4; P<0.01). L also caused further inhibition in the yields of androgen metabolites when incubated with nicotine, implying that some of the inhibitory effects of nicotine could be due to inhibition of AP activity.


CONCLUSIONS
This investigation has shown that nicotine can inhibit the formation of matrix-stimulatory steroid metabolites in fibroblasts, partly due to inhibition of AP activity. Minocycline is a useful adjunct, in reducing the inhibition of androgen metabolism caused by nicotine.
Soory
M
M
Division of Periodontology, Guy's King's and St. Thomas' Dental Institute, King's Dental Hospital, Caldecot Road, SE5 9RW, London, UK. mena.soory@kcl.ac.uk <mena.soory@kcl.ac.uk>
Suchak
A
A
D000328:Adult; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D005881:Gingiva / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007978:Levamisole / Q000494:pharmacology*; D008875:Middle Aged; D008911:Minocycline / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D010521:Periosteum / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
D004791:Enzyme Inhibitors; D007978:Levamisole; D013739:Testosterone; D009538:Nicotine; D000469:Alkaline Phosphatase; D008911:Minocycline