Rat Buccal Mucosa Research Articles

Characterization of alkaline phosphatase from buccal mucosa in young rats

Alkaline phosphatase (APase) is a plasma membrane-integrated protein with unknown function and is found in many different tissues of the body. It is normally not present in squamous epithelium. Nevertheless, it has been demonstrated in developing rat oral epithelium, where it exists together with several different phosphatases. In this study APase was solubilized from rat buccal mucosa and partially purified by gel chromatography followed by ion-exchange chromatography. Three isoenzymes with similar kinetic characteristics but different sensitivities to heat inactivation were obtained. All three had a pH optimum of 10.2 and a Michaelis-Menten constant of 0.3 mM. Combined chromatographic/electrophoretic and histochemical tissue section analysis of APase isoenzymes indicated that the buccal mucosa of young rats contains three APase isoenzymes, two of which are of epithelial origin and the third of endothelial origin.

Metabolism of tobacco specific carcinogens in cultured rat buccal mucosa epithelial cells.

The metabolism of tobacco carcinogens was studied in a potential target for their carcinogenic effects. Rat buccal mucosa cells metabolized several polycyclic aromatic hydrocarbons, e.g., benzo(a)pyrene, benz(b)- and benz(j)-fluoranthene, dibenz(a,j)acridine, N,N-diethylnitrosamine and protein pyrolysate products, 2-amino-3-methylimidazo(4,5-f)quinoline, and 2-amino-3,4-dimethylimidazo(4,5-f)quinoline, as measured by binding of the carcinogens to cellular DNA. The highest level of binding was seen with the nitrosamine followed by the protein pyrolysate products. There was no significant difference in the binding levels between the different polycyclic aromatic hydrocarbons. Cells treated with a non-cytotoxic dose of the non-volatile condensate fraction of regular tobacco smoke increased metabolism as measured by binding to DNA of the protein pyrolysate products, whereas the pretreatment did not have any effect on the metabolism of benzo(a)pyrene, and N,N-diethylnitrosamine. However, the profile of benzo(a)pyrene metabolites released into the media changed. The results indicate that rat buccal mucosa cells metabolize several classes of tobacco specific carcinogens, and that the metabolism is modified by continued exposure to tobacco smoke components.

Metabolism of benzo[a]pyrene by cultured rat and human buccal mucosa cells.

Primary cultures of epithelial and fibroblast cells derived from human oral mucosa were studied for the ability to activate a tobacco smoke carcinogen, benzo[a]pyrene (BP). The cells were exposed to benzo[a]pyrene for 18 h. The cell-free medium was extracted with ethylacetate/acetone, and high-pressure liquid chromatography analysis of this fraction revealed that BP tetrols and diols were the major metabolites formed by both epithelial and fibroblast cells. However, the epithelial cells had a much higher rate of biotransformation of BP as measured by binding to cellular DNA. The mean binding level to human buccal mucosal DNA was among the highest observed in stratified human epithelia. The major BP-DNA adduct was formed by the reaction of the 'bay-region' BP diolepoxide with the exocyclic 2-amino group in guanine. In contrast to human cells, BP phenols and BP 9,10-diol were the major metabolites produced by primary epithelial and fibroblast cells derived from rat buccal mucosa. The DNA binding levels of BP in the two rat cell types were identical, and the binding level was several-fold lower than in the human epithelial cells. When an established rat tongue epithelial cell line (RTE 2) was treated with polycyclic aromatic hydrocarbons--BP and 7,12-dimethylbenz[a]-anthracene--a slight toxic effect was observed. Our results indicate that primary cultures of oral mucosa are able to metabolize BP into its ultimate carcinogenic form at a rate similar to or higher than other potential target tissues for BP-induced carcinogenesis.

Induction of Oral Mucosal Tumors in Hamsters and Rats Treated With Methyl(acetoxymethyl)nitrosamine<xref ref-type="fn" rid="FN2">2</xref>

An oral tumor model has been developed in inbred Syrian golden hamsters by continuous applications every 2 weeks of methyl(acetoxymethyl)nitrosamine [(DMN-OAC) CAS: 56856-83-8; methylnitrosaminomethyl ester acetic acid] at 2 mg/kg body weight alone or by a single application of DMN-OAC followed by continuous twice weekly applications of 12-O-tetradecanoylphorbol 13-acetate (TPA) (1 microgram/animal). Similar studies were done in the W rat buccal mucosa. In the hamsters treated continuously with DMN-OAC, 100% of the tumors were observed in the cheek pouch; none were observed at other sites. In contrast, in the rats treated similarly, only a 67% tumor incidence was observed, of which only 42% were oral tumors. A promoter effect of TPA was observed in hamster cheek pouch tumors induced by DMN-OAC, whereas rat oral mucosa did not respond to TPA treatment.

辺縁性歯周炎におけるポケット上皮の透過性と防衛機構に関する病理組織学的ならびに組織化学的研究

The present histopathological and histochemical study was performed on the periodontal tissues of 100 teeth from autopsy materials and gingivae removed operatively from the 55 patients with marginal periodontitis to investigate a permeability and defense mechanism of the crevicular epithelium in marginal periodontitis. In addition, histochemical reaction was carried out on the lingual and buccal mucosa of rats and mice on which Zinc chloride (4%) had been topically applied to investigate the change in dehydrogenase activity of the epithelium and subepithelial insoluble collagen. The following results were obtained:1) Subepithelial inflammation of the pocket in marginal periodontitis may consist of subepithelial nonspecific inflammatory reaction (vascular dilatation, slight and moderate exudation of serous fluid and leucocyte) and of adjacent immunological response (diffuse infiltration of plasma cell and lymphocyte). 2) There is rather close correlation between intensity of subepithelial inflammation as well as disappearance of the insoluble collagen fiber and increase in intercellular space of the pocket epithelium as well as amount of bacterial plaque in the pocket. 3) The increase in intercellular space of the crevicular epithelium is attributed to serous exudation and responsible for increase in the permeability of the crevicular epithelium. 4) The crevicular epithelial cells may be able to prevent the dilated intercellular space from invasion of plaque bacteria. 5) The crevicular epithelium had high activity of acid phosphatase even in the epithelium with inflammatory change such as increased intercellular edema and desquamation. 6) These findings suggest that the lysosomal enzyme of the epithelial cell contributes to defense mechamism of the crevicular epithelium by hindering bacterial invasion and reducing a harmfull effects of endotoxin, antigenic substance and bacterial products on the pocket wall.

Adrenergic factors influencing the mitotic rate in stratified squamous epithelium of the buccal mucosa of the rat.

1. An in vivo stathmokinetic technique was used to determine the immediate effect of various adrenoceptor agonists and antagonists on the mitotic rate in the stratified squamous epithelium of the rat buccal mucosa. 2. The mitotic rate increased significantly in rats treated with propranolol and with practolol, whereas the mitotic rate decreased significantly in rats treated with metaraminol. In animals treated with isoprenaline and phentolamine the mitotic rate did not differ significantly from the control value. 3. The nature of the involvement of adrenergic mechanisms with cell proliferation is still uncertain but both alpha- and beta-adrenergic mechanisms appear to be associated with the control of cell proliferation.

Regional differences in gradients of dry residue density in oral epithelia of the rat: A quantitative study

Grams of dry weight per cm 3 of tissue (DRD) were determined on the successive histologic layers of rat buccal and palatal mucosa, both of which form thick layers of orthokeratin. The experimental animals were six young adult male albinos of Simonsen strain. Microdissection was used for isolation of tissue fragments from frozendashdried sections, a quartz fibre balance (according to Lowry) for weighing and a split-image microscope for measuring the dimensions of the fragments. The density of basal cells in both tissues was 0.26g/cm 3 and both showed a rise of 12 per cent between basal and lower spinous cells. Succeeding layers of the palate showed a continuous rise, those of cheek a continuous decline. The greatest change in both tissues occurred between granular and keratin layer. Palatal keratin had a density of 0.63g/cm 3, buccal keratin of 0.21g/cm 3. Sample variability was 9–12 per cent of the average per layer per animal and greatest in cheek keratin. Individual variability was 2–6 per cent of the average for six animals. Taking changes in cell size into account, it was concluded that loss of water occurs between granular and keratin layers of the palate, but uptake of water between deeper and superficial keratin cells of the cheek. Different regions of oral orthokeratin thus showed opposite responses to their common fluid environment.