scholarly journals Identification and Localization of G Proteins in Exocrine Glands

1993 ◽  
Vol 4 (3) ◽  
pp. 407-414
Author(s):  
Eileen L. Watson ◽  
Dennis Di Julio ◽  
Dolphine Oda ◽  
Kenneth T. Izutsu ◽  
Constance Oliver
Keyword(s):  
Parotid Gland ◽  
Salivary Glands ◽  
G Proteins ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Cell Physiology ◽  
Exocrine Glands ◽  
Ductal Cells ◽  
Ductal Cell ◽  
Rat Parotid

GTP-binding proteins were identified in rat parotid acinar plasma-enriched membranes (PM) by immunoblot analysis and localized immunohistochemically in the parotid gland as well as in other exocrine glands by using affinity-purified antisera specific for alpha subunits of the G proteins. Isolated rat parotid acinar PM immunoreacted strongly to antisera directed against Gsa, Giα1/α2, Gia3, and Goa; the signal for Goa, however, was weak with crude Go antisera. Immunohistochemical studies to identify and localize Go in rat parotid tissue revealed that antisera to Goα immunoreacted with ductal cells. In addition, strong immunoreactivity to Goa antisera was noted in ductal cells of other salivary glands including rat submandibular, mouse parotid, and mouse submandibular glands. Light labeling of rat parotid and submandibular gland acinar cells was also noted. In contrast, in the rat and mouse pancreas, Go antisera immunoreacted primarily with islet cells. Ductal cells were negative, but there was light labeling of rat pancreatic acinar cells. The apparent ductal specificity of Goa staining was further verified by demonstrating that Goa antisera immunoreacted strongly with HSG-PA cells, a human transformed salivary ductal cell line. The results demonstrate that rat parotid acinar plasma membranes express a number of G proteins including Go and that Go appears to be selectively expressed in the ductal cells of rat parotid gland and other salivary glands. The selective enrichment of Go in ductal cells suggests that this G protein may play an important role in ductal cell physiology.

scholarly journals Localization of the G-protein G(o) in exocrine glands.

1994 ◽  
Vol 42 (1) ◽  
pp. 41-47 ◽  
Author(s):  
E L Watson ◽  
C Oliver ◽  
N D'Silva ◽  
C M Belton
Keyword(s):  
Parotid Gland ◽  
G Protein ◽  
Acinar Cells ◽  
Duct Cell ◽  
Protein G ◽  
Cell Physiology ◽  
Exocrine Glands ◽  
Duct Cells ◽  
Rat Parotid Gland ◽  
Rat Parotid

The GTP-binding protein G(o) was localized immunohistochemically in the rat parotid gland and in other exocrine glands with specific G(o) antibodies. Immunohistochemical studies revealed that affinity-purified G(o alpha) polyclonal antibody (GO/85) immunoreacted primarily with duct cells of the rat parotid gland; immunoreactivity was also noted in duct cells of the rat submandibular, mouse parotid, and mouse submandibular glands. Light labeling of rat parotid and submandibular gland acinar cells was also noted. G(o alpha) antiserum (9072) differing in specificity for epitopes within G(o alpha) produced similar results. This antiserum also immunoreacted with rat submandibular duct cell secretory granule membranes. In contrast, in rat and mouse pancreas G(o alpha) antibodies immunoreacted primarily with islet cells. Duct cells were negative but there was light labeling of rat pancreatic acinar cells. The apparent duct specificity of G(o alpha) staining was further verified by demonstrating that G(o alpha) antibodies immunoreacted with HSG-PA cells, a human transformed salivary duct cell line. Specificity in immunohistochemical labeling of HSG-PA cells was confirmed by Western blot analysis. The results demonstrate that G(o) appears to be selectively expressed in the duct cells of rat parotid gland and other salivary glands. The selective enrichment of G(o) in duct cells suggests that this G-protein plays an important role in duct cell physiology.

scholarly journals Intracellular calcium signalling in rat parotid acinar cells that lack secretory vesicles

1998 ◽  
Vol 330 (2) ◽  
pp. 847-852 ◽  
Author(s):  
Peixin LIU ◽  
John SCOTT ◽  
Peter Matthew SMITH
Keyword(s):  
Parotid Gland ◽  
Calcium Signalling ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Vesicles ◽  
Apical Pole ◽  
Parotid Acinar Cells ◽  
Parotid Duct ◽  
Rat Parotid ◽  
In Cells

Secretory vesicles from pancreatic acinar cells have recently been shown to release Ca2+ after stimulation with Ins(1,4,5)P3 [Gerasimenko, Gerasimenko, Belan and Petersen, (1996) Cell 84, 473-480]. These observations have been used in support of the hypothesis that Ca2+ release from secretory vesicles could be an important component of stimulus secretion coupling in exocrine acinar cells. In the rat, ligation of the parotid duct causes a reversible atrophy of the parotid gland. Most notably, after atrophy the acinar cells are reduced in size and no longer contain secretory vesicles [Liu, Smith, and Scott (1996) J. Dent. Res. 74, 900]. We have measured cytosolic free-Ca2+ concentration ([Ca2+]i) in single, acutely isolated, rat parotid acinar cells, and compared Ca2+ mobilization in response to acetylcholine (ACh) stimulation in cells obtained from control animals to that in cells lacking secretory vesicles obtained after atrophy of the parotid gland. Application of 50-5000 nM ACh to control cells gave rise to a typical, dose-dependent, biphasic increase in [Ca2+]i, of which the later, plateau, phase was acutely dependent on the extracellular Ca2+ concentration. An identical pattern of response was observed with cells obtained from atrophic glands. Low concentrations of ACh (10-100 nM) occasionally produced [Ca2+]i oscillations of a similar pattern in cells from both control and atrophic glands. We were able to show that Ca2+ rises first in the apical pole of the cell and the increase then spreads to the rest of the cell in cells from control glands but not in cells from atrophic glands. However, at present we are unable to determine whether this is due to the lack of secretory vesicles or whether the separation is too small to measure in the smaller acinar cells obtained from atrophic glands. We conclude therefore, that secretory vesicles make no significant contribution to overall Ca2+ mobilization in rat parotid acinar cells, nor are they required for oscillatory changes in [Ca2+]i to occur. However we are unable to eliminate completely any role for secretory vesicles in initiating Ca2+ mobilization at the apical pole of the cell.

scholarly journals Neurofibromin expression by normal salivary glands

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Eloá Borges Luna ◽  
Pâmella Pinho Montovani ◽  
Rafaela Elvira Rozza-de-Menezes ◽  
Karin Soares Cunha
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Acinar Cells ◽  
Staining Intensity ◽  
Neurofibromatosis 1 ◽  
Tissue Type ◽  
Sublingual Gland ◽  
Minor Salivary Glands ◽  
Expression Levels ◽  
Ductal Cells

AbstractIntroductionNeurofibromin, a protein encoded by theNF1gene, is mutated in neurofibromatosis 1, one of the most common genetic diseases. Oral manifestations are common and a high prevalence of hyposalivation was recently described in individuals with neurofibromatosis 1. Although neurofibromin is ubiquitously expressed, its expression levels vary depending on the tissue type and developmental stage of the organism. The role of neurofibromin in the development, morphology, and physiology of salivary glands is unknown and a detailed expression of neurofibromin in human normal salivary glands has never been investigated.AimTo investigate the expression levels and distribution of neurofibromin in acinar and ductal cells of major and minor salivary glands of adult individuals without NF1.Material and methodTen samples of morphologically normal major and minor salivary glands (three samples of each gland: parotid, submandibular and minor salivary; and one sample of sublingual gland) from individuals without neurofibromatosis 1 were selected to assess neurofibromin expression through immunohistochemistry. Immunoquantification was performed by a digital method.ResultsNeurofibromin was expressed in the cytoplasm of both serous and mucous acinar cells, as well as in ducts from all the samples of salivary glands. Staining intensity varied from mild to strong depending on the type of salivary gland and region (acini or ducts). Ducts had higher neurofibromin expression than acinar cells (p = 0.003). There was no statistical association between the expression of neurofibromin and the type of the salivary gland, considering acini (p = 0.09) or ducts (p = 0.50) of the four salivary glands (parotid, submandibular, minor salivary, and sublingual gland). Similar results were obtained comparing the acini (p = 0.35) and ducts (p = 0.50) of minor and major salivary glands. Besides, there was no correlation between the expression of neurofibromin and age (p = 0.08), and sex (p = 0.79) of the individuals, considering simultaneously the neurofibromin levels of acini and duct (n = 34).ConclusionNeurofibromin is expressed in the cytoplasm of serous and mucous acinar cells, and ductal cells of salivary glands, suggesting that this protein is important for salivary gland function.

Electrolyte and inulin spaces of rat salivary glands and pancreas

1960 ◽  
Vol 199 (4) ◽  
pp. 649-652 ◽  
Author(s):  
L. H. Schneyer ◽  
C. A. Schneyer
Keyword(s):  
Parotid Gland ◽  
Salivary Glands ◽  
Extracellular Fluid ◽  
Electrolyte Composition ◽  
Tissue Preparation ◽  
Sodium Potassium ◽  
Mammalian Muscle ◽  
Rat Parotid Gland ◽  
Rat Parotid ◽  
Volumes Of Distribution

Inulin, sodium, potassium and chloride levels were determined on serum and submaxillary, parotid and pancreatic glands of inulin-administered nephrectomized rats. Methods of tissue preparation and analysis were examined in some detail. From data obtained, volumes of inulin and electrolyte distribution were calculated. Volumes of distribution in submaxillary, parotid and pancreatic glands, in that order, were, for inulin, 198 ml/kg, 257 ml/kg and 209 ml/kg; for sodium, 232 ml/kg, 318 ml/kg and 275 ml/kg; and, for chloride, 365 ml/kg, 460 ml/kg and 388 ml/kg. Comparison of these values led to the conclusion that intracellular sodium in these glands is possible and that intracellular chloride is likely. Intracellular potassium seems present in concentration similar to that in mammalian muscle. From electrolyte data and levels of amylase in parotid gland and its secretion, it is speculated that parotid secretion could be formed from a small fraction (approx. 10%) derived from unmodified intracellular fluid to which is then added solution having electrolyte composition of extracellular fluid. The closely isotonic secretion of rat parotid gland can thus be predicted without assuming appreciable reabsorption of electrolytes or water.

scholarly journals Lithium-induced reduction in intracellular inositol supply in cholinergically stimulated parotid gland

1986 ◽  
Vol 234 (1) ◽  
pp. 199-204 ◽  
Author(s):  
C P Downes ◽  
M A Stone
Keyword(s):  
Parotid Gland ◽  
Acinar Cells ◽  
Phospholipid Metabolism ◽  
Cholinergic Stimulation ◽  
Inositol Phosphatase ◽  
Agonist Stimulation ◽  
Rat Parotid Gland ◽  
Inositol Phospholipid ◽  
Rat Parotid ◽  
Phosphatidylinositol 4

The effects of lithium and cholinergic stimulation on inositol phospholipid metabolism have been assessed using rat parotid gland slices and isolated acinar cells labelled with 32Pi. Cholinergic stimulation using carbachol caused substantial breakdown of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) and enhanced labelling of phosphatidate (PA) and phosphatidylinositol (PtdIns). Lithium alone had little effect upon 32Pi incorporation, but in combination with carbachol it greatly reduced the PtdIns labelling response to the agonist. Instead the label accumulated in a lipid identified as cytidine monophosphorylphosphatidate. There was also an enhancement of the PA labelling response to carbachol. These lithium-induced alterations in agonist-stimulated phospholipid metabolism were reversed if 10-30 mM-inositol was included in the incubation medium. Despite reduced PtdIns synthesis, lithium had relatively little effect on polyphosphoinositide labelling in stimulated cells. Resynthesis of polyphosphoinositides was monitored in acinar cells that had been stimulated with carbachol and then treated with atropine to block muscarinic receptors. Treatment with lithium during the carbachol-stimulation phase reduced the rate of phosphatidylinositol 4-phosphate synthesis, but had no significant effect upon PtdInsP2. The results suggest that an active inositol phosphatase pathway is essential to maintain intracellular inositol levels, but that PtdInsP2 synthesis is not markedly reduced by a substantial fall in intracellular inositol. This implies a close control over the rates of PtdInsP2 breakdown and resynthesis during agonist stimulation.

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