EFFECT OF NICOTINE ON ARACHIDONIC-ACID METABOLITES AND EPITHELIAL PARAMETERS IN RAT ORAL-MUCOSA

This study examined the effects of nicotine on oral mucosal levels of eicosanoids and on histologic parameters, including keratinocyte proli feration. Surgically-created canals in the mandibular lips of 20 male Sprague Dawley rats received either nicotine or saline in a cotton pel let twice daily for six weeks. Thromboxane B-2 (TxB(2)) levels were de pressed (P<0.05) in nicotine treated tissues compared to saline treatm ent (5.8+/-1.0 vs 13.4+/-2.1 pg/mg). Within the nicotine group, TxB(2) concentrations were lower (P<0.05) at the nicotine site compared to t he posterior site (18.3+/-5.4 pg/mg). There was also a trend towards r educed 6-keto-PGF(1 alpha) in the nicotine-treated tissues compared to saline-exposed sites. These alterations in cyclooxygenase metabolites were not accompanied by changes in epithelial proliferation or histol ogic parameters. 12(S)-hydroxveicosatetranoic acid (12-HETE) and leuko triene B-4 (LTB(4)) mere not affected by nicotine. Therefore, nicotine may not be directly responsible for the hyperplasia at habitual tobac co placement sites, but may contribute to alterations in cyclooxygenas e products of arachidonic acid metabolism.