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PubMed1987

Effects of reserpine treatment on the ultrastructure of rat parotid and submandibular gland.

The chronically reserpine-treated rat has been used as an animal model for the disease cystic fibrosis, a generalized exocrinopathy. Ultrastructural changes in the parotid and submandibular gland occurring during the seven-day treatment with reserpine were studied by transmission electron microscopy. In the parotid gland, marked changes were observed in the size and structure of the zymogen granules. In fasted control animals, most parotid acinar cells have granules with a virtually homogeneous, electron-dense appearance. During the first three days of treatment, most cells have enlarged, electron-translucent granules. After the third day, and most pronounced at day six and seven, many granules are irregularly electron-dense. In the submandibular gland, reserpine causes a gradual increase in the relative volume of the cell that is occupied by mucus. The ultrastructural changes are discussed in relation to metabolic and biochemical effects of reserpine treatment on salivary glands.

Animals↗
PubMed1987

Short-term inhibition of cellular autophagy by isoproterenol in the submandibular gland.

The present study examines the short-term (i.e. 10 min after injection) influence of isoproterenol on cellular autophagy in the rat submandibular gland. The volume fraction of autophagic vacuoles was significantly reduced, suggesting that an anticatabolic reaction, namely inhibition of cellular autophagy, is an early and significant event in the growth of the submandibular gland which is known to occur with long-term isoproterenol treatment.

Animals↗
PubMed1979

Effects of adrenergic agonists on the oxygen uptake and amylase output in rat submandibular gland slices.

Oxygen uptake and amylase output in rat submandibular gland slices were measured by utilizing adrenergic agonists. Adrenaline, noradrenaline and isoproterenol significantly stimulated the oxygen uptake and amylase output. In the presence of propranolol or phenoxybenzamine, adrenaline-stimulated oxygen uptake was obviously blocked. Adrenaline-stimulated amylase output was inhibited by propranolol, but was not inhibited by phenoxybenzamine. The increase in oxygen uptake by nornol-stimulated oxygen uptake and amylase output were strongly inhibited by propranolol. The oxygen uptake due to isoproterenol was little affected by phenoxybenzamine. These results suggest that the increase in oxygen uptake seen with adrenergic agonists is mediated by both alpha- and beta-receptors, and that the amylase output is evoked through the stimulation of beta-receptors.

Adrenergic Agonists↗
PubMed1982

Ultrastructure of the "separating zone" of rat submandibular gland striated duct cells.

The separating zone of rat submandibular gland striated duct cells were studied in detail by electron microscopy. In order to get optimal stimulation of the glands the animals were starved for 24 h followed by feeding 15 min before sacrifice, and tissue removal. The separating zone is morphologically defined by numerous filaments which are located within the apical part of cell. Some of the filaments had a parallel arrangement, running horizontally and being attached to belt desmosomes at the cell periphery. Following the shedding of apical blebs, these filaments appeared to constitute the luminal boundary of striated duct cells. It was observed that the separating zones showed different degrees of density. This is supposed to reflect different stages in the reconstruction of the apical cell surface. It is thus considered that the separating zone, with numerous filaments, is of importance both of the apical secretion per se, and the formation of the new apical cell membrane.

Animals↗
PubMed1996

Low affinity purinergic receptor modulates the response of rat submandibular glands to carbachol and substance P.

The effect of extracellular ATP on the intracellular calcium concentration ([Ca2+]i) in rat submandibular glands was tested. The dose-response curve for ATP was biphasic with a first increase in the 1-30 microM concentration range and a further increase at concentrations higher than 100 microM. Among ATP analogs, only benzoyl-ATP stimulated the low affinity component. ATP tau S blocked this response. All the other analogs tested reproduced the high-affinity low capacity response. Magnesium and Coomassie blue selectively blocked the low affinity component. High concentrations of ATP blocked the increase of the intracellular calcium concentration [Ca2+]i in response to 100 microM carbachol. By itself, substance P (100 pM-1 microM) increased the [Ca2+]i. One mM ATP potentiated the response to concentrations of substance P higher than 10 nM. This potentiation was reversed by extracellular magnesium. Carbachol 100 microM and substance P (100 pM-1 microM) increased the release of inositol trisphosphate (IP3) from polyphosphoinositides (polyPI). Activation of the low affinity ATP receptors did not activate the polyPI-specific phospholipase C but inhibited its activation by 100 microM carbachol (-50%) and by 100 nM substance P (-60% at 1 nM substance P and -40% at 100 nM substance P). Substance P induced a strong homologous desensitization: a preincubation with 1 nM substance P nearly completely abolished the response to 1 microM substance P. When the cells were exposed to ATP before the second addition of substance P, the purinergic agonist partially restored the response to the tachykinin without totally reversing the desensitization. It is concluded that two types of purinergic receptors coexist in rat submandibular glands; a high-affinity, low capacity receptor which remains pharmacologically and functionally undefined and a low affinity site, high capacity receptor of the P2z type coupled to a non-selective cation channel. The occupancy of these low affinity sites blocks the increase of the [Ca2+]i in response to a muscarinic agonist and the activation of polyPI-specific phospholipase C by carbachol and substance P. It potentiates the effect of high concentrations of substance P on the [Ca2+]i.

Adenosine Triphosphate↗
PubMedDate not supplied

Schwannoma of the submandibular gland.

Neurilemmomas (schwannomas) are solitary neurogenic tumors that arise from cells of the neural sheath. They are slow growing and represent a proliferation of Schwann cells. Extracranial neurogenic tumors of the head and neck are uncommon, with benign tumors occurring with greater frequency than malignant tumors. These tumors often mimic primary or metastatic disease in the head and neck. Schwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor, with most presenting in the parotid gland originating from a peripheral branch of the facial nerve. An unusual case of neurilemmoma of the submandibular gland is presented, and the literature concerning this subject is reviewed. We believe this tumor originated in an autonomic nerve of the submandibular gland. The mass was discrete and well demonstrated on CT scan. Total excision of the gland resulted in complete resolution of symptoms with no cranial nerve deficits.

Adult↗
PubMed1990

A new member of the glutamine-rich protein gene family is characterized by the absence of internal repeats and the androgen control of its expression in the submandibular gland of rats.

A cDNA, corresponding to a rat submandibular mRNA which is accumulated at a 20-fold higher level in males than females, has been isolated. The predicted protein, SMR2, has a calculated molecular mass of 15.4 kDa and is rich in glutamine/glutamic acid, proline, and asparagine/aspartic acid, a characteristic of the so-called salivary glutamine-rich proteins (GRPs) of the submandibular gland of rats. Nucleotide sequence comparisons indeed revealed strong similarities between the sequences of the SMR2 mRNA and that of GRPs, except in the region encoding the carboxyl-terminal part of the proteins. In particular, the SMR2 mRNA contains the 5'-untranslated region and the signal peptide region shared by both groups of GRPs and proline-rich proteins (PRPs). A major difference is that, in SMR2, the peptidic motif which is repeated four or five times in GRPs, is only found once. The SMR2 gene is about 3.5 kilobases in length and contains 4 exons. The second intron, which does not exist in characterized GRP genes, splits the "transition" region which separates the repetitive sequences from the signal peptide. This structure is reminiscent of that found in most PRP genes, strengthening the hypothesis that GRP and PRP genes have the same ancestral origin.

Amino Acid Sequence↗
PubMed1976

Ultrastructure of the main excretory duct of the cat submandibular gland.

The main excretory ducts (MED's) from the submandibular gland of adult cats were examined by electron microscopy. The ducts consisted of a pseudostratified epithelial lining surrounded by abundant connective tissue and numerous, small, longitudinally-oriented blood vessels. The taller epithelial cells were closely coherent, without the luminal clefts between adjacent cells that are characteristic of rat MED's. In the cat, these cells lacked basal membrane specialization, but showed considerable lateral interdigitation. Some microvilli were present on the apical surface. In a few rare cells, the luminal surface bore cilia of typical appearance. The smaller, pyramidal basal cells had irregular basal surfaces that gave rise to one or more long cytoplasmic processes. The basal surface of the pyramidal cells was studded with hemidesmosomes. The cytoplasms contained abundant tonofilaments, which sometimes aggregated in prominent perinuclear bundles. Occasional goblet cells were present in the duct wall. MED's perfused either in situ or in a perfusion chamber with Locke's solution also were studied. Even after perfusion of 160 minutes duration, the ultrastructure of the ductal epithelium showed remarkably few alterations. The MED model system thus remains stable long enough to carry out physiological experiments which may produce ultrastructural alterations.

Animals↗
PubMed1997

Osmotic flow transients during acetylcholine stimulation in the perfused rat submandibular gland.

Osmotic stress was applied to the perfused rat submandibular gland during steady-state fluid secretion. Alterations of perfusate osmolarity, by addition or withdrawal of sucrose or NaCl, caused transient changes in secretory rate during continuous stimulation with 1 microM acetylcholine (ACh). Hyposmotic perfusates transiently increased, and hyperosmotic perfusates transiently reduced, the secretory rate. The transients were attributed to changes in osmotic flow resulting from changes in the instantaneous transepithelial osmotic gradient. The time course of the change in interstitial osmolarity was determined by using a Cl- electrode to record the changes in interstitial Cl- concentration following a step change in perfusate Cl- concentration. From the calculated changes in interstitial osmolarity and the resulting changes in secretory rate, the osmotic water permeability of the secretory pathway was estimated to be greater than 15.0 +/- 1.2 microliter (mosmol 1-1)-1 min-1 (g wet weight)-1 (9.8 x 10(-6) +/- 0.8 x 10(-6) l atm-1s-1g-1). The transepithelial gradient required to sustain steady state, ACh-evoked secretion would therefore be less than 16 mosmol l-1 NaCl, which is consistent with previous micropuncture data indicating that the luminal fluid is approximately isosmotic.

Acetylcholine↗
PubMed1991

Accumulation and localization of two adult acinar cell secretory proteins during development of the rat submandibular gland.

The seromucous acinar cells of the adult rat submandibular gland secrete a characteristic mucin glycoprotein and a family of unusual glutamine/glutamic acid-rich proteins (GRP). Monoclonal antibodies to the mucin and GRP localized in a very few Type III cells in glands of newborn and 1 day-old rats, using light and electron microscopic immunocytochemistry. Both mucin and GRP reactivities were present in the polymorphic Type IIIP granules during the 1st postnatal week. By 9 days after birth, the granules contained both mucin and GRP and were mucous-like in appearance. At earlier stages, however, cells containing only GRP or mucin could be found, indicating that the initiation of GRP and mucin biosynthesis may not be coordinately regulated. No reactivity was seen in the neonatal Type I cells or in duct cells at any age. Northern and Western blot analysis showed GRP mRNA and protein levels to be barely detectable at birth, with marked increases during the first 2 postnatal weeks. In contrast, Western blots of B1-immunoreactive proteins (B1-IP) showed levels highest in the 1st week and markedly decreased in the adult. Immunocytochemical colocalization, using gold particles of different sizes, showed that the B1-IP, mucin, and GRP colocalized in the granules. These results strengthen the hypothesis that the adult acinar cells develop from the neonatal Type III cells. No evidence was obtained for the involvement of Type I cells in the pathway of acinar cell development.

Aging↗
PubMed1986

Short-term primary culture of acinar-intercalated duct complexes from rat submandibular glands.

Acinar-intercalated duct complexes dissociated from rat submandibular glands have been shown to be an excellent model for studying secretory responses of salivary gland components. However, they are functionally normal for only a few hours. We undertook a systematic manipulation of primary culture conditions in an attempt to extend the useful life of the complexes. The major modifications that were tested were increased oxygenation in increments to 95%; substitution of norepinephrine or carbamylcholine or both for isoproterenol in the medium; different sources of collagen for and addition of laminin, fibronectin and/or type IV collagen to the matrix gel; and varying the thickness of the collagen gel, richness of the cell suspension inoculate, and sources and concentrations of sera in the medium. Progress was monitored by light microscopic evaluation of routine sections of specimens until improved maintenance of acinar and other cells warranted carrying parallel cultures for biochemical, histochemical, and ultrastructural analyses. Best results were obtained with 90% O2, laminin in rat tail collagen gel, 10% fetal bovine serum, and 3 microM isoproterenol. Morphologically, there was good survival of acini and intercalated ducts after 1 d, with decreased acinar size being correlated with secretory response to the isoproterenol. Reorganization and considerable mitotic activity were seen at 2, 3, and 4 d, with most clusters of cells becoming much larger than the original complexes. During this period acinar cells steadily became less differentiated and their numbers decreased in proportion to intercalated duct or undifferentiated cells. However, there was good overall survival through 7 d. Biochemical analysis indicated that the cells were able to maintain significant biosynthetic activity for 4 d, with DNA, RNA, protein, and glycoprotein synthetic rates increasing over the culture period, but the secretory capacity of the cells diminished during the primary culture period, with mucin biosynthesis and secretion decreasing significantly after 1 d in culture.

Animals↗
PubMed1984

Histochemical studies on Concanavalin A-binding in experimental carcinoma of the mouse submandibular gland.

The lectin, Concanavalin A(Con A) has been used to localize specific sugar residues (D-glucose, D-mannose and D-fructose) in premalignant lesions and squamous-cell carcinomas induced following cryosurgery of the mouse submandibular gland. The original Con A-horseradish peroxidase (HRP) technique as well as its combination with periodate oxidation and subsequent reduction by borohydrate were used to compare the epithelial elements during submandibular gland carcinogenesis. Granules in the granular convoluted tubule cells which were weakly reactive to the Con A-HRP method were not present in the premalignant duct like structures. The epithelium of premalignant lesions, duct-like structures, multicystic lesions, and squamous-cell carcinomas were positive for the cell-surface and intercellular substances; and basement membranes and stromal fibers were also positive. The results indicated that throughout malignant transformation of the ductal segments, premalignant epithelia lost Con A-HRP-staining granules and that Con A-binding patterns in induced squamous-cell carcinomas were similar to those found in squamous-cell epithelium.

Animals↗
PubMed1985

Acinar structure and membrane regionalization as a prerequisite for exocrine secretion in the rat submandibular gland.

The significance of glandular organization in exocrine secretion was examined by analysing the functional and morphological features of the dissociated rat submandibular gland with special reference to the acinar structure and luminal specialization. The digestion of the gland with collagenase (C preparation) produced relatively large cellular masses having well-preserved acinar structures. When EGTA and the proteolytic enzyme Dispase were added to the C preparation (CED preparation), the gland was dissociated into small cellular aggregates in which the acinar structure disintegrated. Upon stimulation with either isoproterenol or dibutyryl cyclic AMP, a large amount of peroxidase, one of the secretory products of the rat submandibular gland, was released from C-treated cells, while discharged peroxidase was greatly reduced after the CED preparation was used. Measurements of dye exclusion, oxygen consumption, protein synthetic activity and receptor binding, as well as ultrastructural features and the absence of inhibitory effects of EGTA and Dispase, suggested that the reduced secretory response of CED-treated cells was not attributable to cellular death, denaturation of receptors or the inhibitory effects of EGTA and Dispase. When the localization of dipeptidyl aminopeptidase IV was surveyed by both enzyme histochemistry and immuno-histochemistry, the luminal plasma membrane was the exclusive site for the reaction in C-treated cells as well as intact acini, whereas the entire cell surface was reaction-positive in CED-treated cells. In addition, the luminal microfilament system and tight junctions, as revealed by nitrobenz-oxadiazole-phallacidin staining and freeze-replica studies, respectively, were well-preserved in the C-treated cells, but considerably disorganized in the CED-treated cells. All these results strongly suggest that: (1) luminal specialization plays an important role in exocrine secretion; and (2) normal acinar arrangement provides the luminal specialization.

Animals↗
PubMed2001

Guanylin and uroguanylin in the parotid and submandibular glands: potential intrinsic regulators of electrolyte secretion in salivary glands.

The intestinal peptides guanylin and uroguanylin regulate the electrolyte/water transport in the gastrointestinal epithelium via activation of cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis gene product. Because a major but incompletely understood function of the salivary glands is the CFTR-mediated secretion of an electrolyte-rich fluid, we investigated the rat and guinea pig parotid and submandibular glands for expression, cellular distribution, and subcellular localization of guanylin and uroguanylin. RT-PCR analyses with guanylin and uroguanylin-specific primers revealed that both peptides are highly expressed in the parotid and submandibular glands. At the translational level, western blotting analyses with peptide-specific guanylin and uroguanylin antibodies identified the expected 12.5-kDa immunoreactive peptides in these organs. At the cellular level, guanylin and uroguanylin were exclusively confined to epithelial cells of the intralobular and interlobular ducts. At the subcellular level, the immunoreactivities were localized by preembedding immunoelectron microscopy to small vesicles which were concentrated at the apical part of the secretory epithelial cells. The expression and cell-specific localization of guanylin and uroguanylin in the salivary glands indicate that these peptides may be specifically involved in the regulation of CFTR-mediated electrolyte/water secretion in the salivary gland ductal system.

Animals↗
PubMedDate not supplied

Acetylcholine and cholinesterase in submandibular glands of rats given armin and obidoxime.

The effects of obidoxime, a pyridinium oxime, on the cholinesterase activity and acetylcholine content of the submandibular glands of rats poisoned with armin, an organophosphorus anticholinesterase agent, were studied. The results indicate that obidoxime-induced reactivation of phosphorylated cholinesterase can suppress completely the increase in the concentration of acetylcholine that develops within the submandibular gland after administration of armin alone.

Acetylcholine↗
PubMed1988

Suppression of intercellular communication in acinar cells from rat submandibular gland by cholinergic and adrenergic agonists.

The effects of cholinergic and adrenergic agonists on intercellular communication in isolated acini of rat submandibular gland were evaluated using dye-coupling. Cells injected with Lucifer Yellow CH showed diffusion of the dye to their coupled neighbors under the control condition. Addition of acetylcholine (ACh) and carbachol (CCh) at concentrations higher than 10(-6) M rapidly and reversibly suppressed the dye-coupling. This effect by 10(-4) M ACh or 10(-4) M CCh was blocked by the addition of 10(-6) M atropine. The suppressive effects of 10(-4) M adrenaline and 10(-4) M noradrenaline were weaker than those of 10(-4) M ACh. Treatment with 10(-4) M isoproterenol did not inhibit the dye-coupling and the suppressive effect by 10(-4) M adrenaline was blocked by the addition of 10(-5) M phenoxybenzamine. The inhibition of dye-coupling by ACh and adrenaline was blocked by the addition of 10(-5) M verapamil, 10(-4) M W-7 and 1.5 x 10(-5) M H-7, but not by 1.5 x 10(-5) M HA1004. These results suggest that the muscarinic action of cholinergic agonists and the alpha-action of adrenergic agonists might suppress the intercellular communication of the acinar cells in the rat submandibular gland, possibly through the increase of calcium influx and the activation of protein kinase C.

Acetylcholine↗
PubMed2003

Sialolith of the submandibular gland with bone formation.

An unusual case of sialolith with bone formation, occurring in the submandibular gland of a 33-year-old woman, is reported. In addition to the irregularly laminated structure of sialolith, sparsely scattered foci of bone tissue were found. Some of them were mature, lamellar bone with lacunae containing osteocytes, endosteum and a bone marrow-like element. Others were immature bone associated with or without multinucleated giant cells. Foci of bone tissue were in contact with caliculi or fibrous tissue, and no epithelial component was seen around them. These observations suggest that bone formation in the present case may be in the nature of pathological ossification, and that in the earlier stage, the bone that is deposited is woven and is replaced through successive remodeling cycles by lamellar bone. This is the first case of sialolith with bone formation, although sialolithiasis is a common disease of the salivary glands.

Adult↗
PubMed1985

Characterization of muscarinic cholinergic receptors in the submandibular gland of the rat.

The specific muscarinic ligand [3H]quinuclidinyl benzilate ([3H]QNB) was used to label acetylcholine receptors in the submandibular gland of the rat. Specific binding of [3H]QNB increased linearly with tissue concentration in the range of 0.02-0.3 mg of protein/ml. Kinetic analysis of [3H]QNB binding revealed the presence of a single population of high affinity binding sites, with a dissociation constant of 87.2 pM and a Hill coefficient of 0.95. The binding was saturable and the receptor density was 214 fmol/mg of protein. The rate constants at 37 degrees C for association and dissociation of the [3H]QNB-receptor complex were 5.98 X 10(-8) M-1 X min-1 and 6.6 X 10(-3) X min-1, respectively. The ratio k-1/k+1 gave a Kd value of 11.1 pM, similar to the Kd value (13.1 pM) determined by kinetic parameters when extrapolated at infinitely low receptor concentration. Muscarinic antagonists displaced [3H]QNB from muscarinic receptors with a Hill coefficient near to 1.0. Displacement curves for muscarinic agonists and for the atypical antagonist pirenzepine had Hill values significantly less than one. In the presence of 0.1 mM GPP(NH)P, the potency of agonists but not antagonists in displacing [3H]QNB binding decreased 2 to 3-fold. The [3H]QNB binding site was sensitive to the inhibitory effect of various sulfhydryl reagents. Repeated treatments of rats with an acetylcholinesterase inhibitor led to a decreased density of muscarinic receptors in the submandibular gland. This alteration was specific for the muscarinic recognition site and was paralleled by a reduced sensitivity to carbachol.

Animals↗