Phospholipase D is involved in the formation of Golgi associated clathrin coated vesicles in human parotid duct cells.

Phospholipase D (PLD) has been implicated in many cellular functions, such as vesicle trafficking, exocytosis, differentiation, and proliferation. The aim of this study was to characterize the role of PLD in HSY cells, a human cell line originating from the intercalated duct of the parotid gland. As the function and intracellular localization of PLD varies according to cell type, initially, the intracellular localization of PLD1 and PLD2 was determined. By immunofluorescence, PLD1 and PLD2 both showed a punctate cytoplasmic distribution with extensive co-localization with TGN-46. PLD1 was also found in the nucleus, while PLD2 was associated with the plasma membrane. Treatment of cells with the primary alcohol 1-butanol inhibits the hydrolysis of phosphatidylcoline by PLD thereby suppressing phosphatidic acid (PA) production. In untreated HSY cells, there was only a slight co-localization of PLD with the clathrin coated vesicles. When HSY cells were incubated with 1-butanol the total number of clathrin coated vesicles increased, especially in the juxtanuclear region and the co-localization of PLD with the clathrin coated vesicles was augmented. Transmission electron microscopy confirmed that the number of Golgi-associated coated vesicles was greater. Treatment with 1-butanol also affected the Golgi apparatus, increasing the volume of the Golgi saccules. The decrease in PA levels after treatment with 1-butanol likewise resulted in an accumulation of enlarged lysosomes in the perinuclear region. Therefore, in HSY cells PLD appears to be involved in the formation of Golgi associated clathrin coated vesicles as well as in the structural maintenance of the Golgi apparatus.

Different role of isoproterenol and NOS inhibitors on salivary ducts of rats.

OBJECTIVES: Nitric oxide (NO) is a diffusible intracellular messenger that is present in saliva. Chronic treatment with isoproterenol, a beta receptor agonist, stimulates the release of NO from acinar cells and induces salivary gland hypertrophy. The aim of this study was to investigate the effect of NO synthesis inhibitors and isoproterenol on rat salivary glands. We analyzed salivary gland weight and the number of ducts per unit area (0.5mm(2)) by NADPH-diaphorase histochemistry (to identify the presence of the enzyme NO synthase-NOS) and haematoxylin-and-eosin (HE). METHODS: For 8 days male Wistar rats received daily single intraperitoneal injections of saline or a NOS inhibitor (40mg/kg N(omega)-nitro-L-arginine L-NOARG or N(omega)-nitro-l-arginine methyl ester L-NAME). This was followed, 30min later, by subcutaneous injection of isoproterenol (2 or 5mg/kg) or saline. RESULTS: Isoproterenol increased parotid and submandibular gland weights. Isoproterenol (2mg/kg) induced a decrease of ducts per unit area inversely correlated to the weight of the parotid gland. This effect was augmented by L-NAME. In the submandibular gland L-NAME attenuated isoproterenol (2mg/kg) weight increase. In the submandibular gland isoproterenol and NOS inhibitors induced an increase in ducts per unit area (HE and NADPH-diaphorase). No effect was observed in the sublingual gland. CONCLUSION: To our knowledge this is the first description of isoproterenol and NOS inhibitors increasing duct density in the submandibular gland. Our results corroborate the hypothesis that NO plays different roles in parotid and submandibular glands.

Vascular endothelial growth factor in minor salivary glands: effect of ageing.

Morphological and physiological age changes are described in human salivary glands. Vascular endothelial growth factor (VEGF) is neoangiogenic growth factor found in normal salivary glands. Considering the neoangiogenic properties of VEGF and its important function in inflammation, repair and, probably, in oral mucosa homeostasis, the purpose of the present study was to evaluate the effect of ageing on the immunolocalization of VEGF in minor salivary glands. Paraffin-embedded tissue blocks containing normal labial salivary glands were retrieved and classified according to the patients' age in two groups (< 20 and > 40-year-old). The biotin-streptavidin-peroxidase system was used to detect the VEGF antigen. The results demonstrated that the mean level of VEGF immunoreaction in the young group was not statistically different from the old group when compared by the Mann-Whitney U-test (P = 0.54). This may indicate that although salivary flow reduction may develop in old patients, some properties of the salivary glands may not be affected.

Estudo estereológico dos diferentes componentes estruturais de glândulas submandibulares de ratos machos e fêmeas / Stereological study of the various morphologic structures of male and female rat submandibular glands

Na presente pesquisa, avaliou-se as dimensöes morfométricas de ácinos, ductos intercalares, ductos excretores e estroma de glândulas submandibulares de ratos de ambos os sexos. A análise dos resultados mostrou que: a) a massa glandular dos machos foi 42 por cento maior do que nas fêmeas; b) os ácinos exibiram densidade de volume, densidade de superfície e relaçäo superfície-volume maiores nas fêmeas e volume nuclear e volume total do compartimento maiores nos machos; c) as densidades de volume e superfície do compartimento dos ductos intercalares foram maiores nas fêmeas e o seu volume nuclear foi maior nos machos; d) a densidade de superfície dos ductos excretores foi maior nos animais fêmeas; e) o volume total do estroma foi significativamente maior nos machos; f) o número absoluto de células do estroma foi maior nos animais machos, e nos demais compartimentos näo se observou diferenças estatisticamente significantes; g) o número de ácinos foi semelhante nos machos e fêmeas. Os resultados obtidos indicaram que as glândulas submandibulares dos ratos machos exibem diferenças detectáveis pela morfometria, nos compartimentos dos ácinos, ductos intercalares, ductos excretores e estroma em relaçäo às fêmeas

The maturation of convoluted granular tubule cells from mouse submandibular glands during its postnatal development: increase in the cell size

We studied the evolution of nuclear and cytoplasmic volume and of the cytoplasm-nucleus ratio of convoluted granular tubule secretory cells in the submandibular glands of male albino Swiss mice at 21, 28, 35, 42 and 56 days of age. Nuclear volume was measured on 0.25um sections by morphometric method of Bach and the volume densities of nucleus and cytoplasm were determined by point-count volmetry. The date were used to calculate the cytoplasm/nucleus ratio and cytoplasmic volume. The nuclear volume of convoluted tubule cells decreased by 44.6% over the study period, where as the cytoplasmic volume increased markedly by 126.2% from 21 to 35 days of postnatal life, with no statiscally significant increases occurring thereafter. The cytoplasm/nucleus ratio increased by 331.3% over the study period

Inverted ductal papilloma of minor salivary gland origin: morphological aspects and cytokeratin expression.

Ultrastructural features and cytokeratin expression of inverted ductal papillomas of minor salivary gland origin were studied. Under the electron microscope, an increased number of desmosomes and mucus-like granules in some cells were the most striking features. Immunohistochemical study revealed that tumor cells displayed strongly positive reactions with cytokeratins 13 and 14, and less strong reactions with cytokeratins 7, 8, 18 and 5D3. These results support the hypothesis that an inverted ductal papilloma can be derived from the proximal portion of a salivary gland excretory duct.