Expression of prostaglandin E2 receptor in hamster buccal pouch: effect of benzo (a) pyrene and nicotine

Prostaglandin E2 (PGE2) plays an important role in the maintenance of oral mucosal integrity. In this study, we characterized PGE2 receptor binding in the buccal mucosa of Syrian hamster and assessed the effect of nicotine (NC) and benzo (a) pyrene (BP), the two major ingredients in cigarette smoke, on this receptor. Adult male animals were treated for 4 weeks by apical swabbing of the buccal pouch with corn oil (control, C), 1 mM NC, BP, or NC + BP in corn oil, twice a day, 5 days a week. The results obtained with the untreated group revealed the presence of a specific PGE2 receptor consisting of two binding sites (high affinity with Kd = 1.52 nM and Bmax = 37 fmol/mg protein and low affinity with Kd = 813 nM and Bmax = 1.29 pmol/mg protein). The treatment with NC, BP, and NC + BP caused a significant decrease in PGE2 receptor binding (specific binding: 10.20 +/- 0.42, 6.84 +/- 1.32**, 6.58 +/- 0.67** and 5.88 +/- 1.03** fmol/mg protein; C, NC, BP, and NC+BP, respectively; Mean +/- SD, n = 5, **p < 0.01). The data suggest that decreased receptor binding for PGE2 in the buccal mucosa may be the cause for the adverse effect of cigarette smoke on the health of oral mucosa.