Parotid Glands In Response Research Articles

A Novel Objective Sour Taste Evaluation Method Based on Near-infrared Spectroscopy

One of the most important themes in the development of foods and drinks is the accurate evaluation of taste properties. In general, a sensory evaluation system is frequently used for evaluating food and drink. This method, which is dependent on human senses, is highly sensitive but is influenced by the eating experience and food palatability of individuals, leading to subjective results. Therefore, a more effective method for objectively estimating taste properties is required. Here we show that salivary hemodynamic signals, as measured by near-infrared spectroscopy, are a useful objective indicator for evaluating sour taste stimulus. In addition, the hemodynamic responses of the parotid gland are closely correlated to the salivary secretion volume of the parotid gland in response to basic taste stimuli and respond to stimuli independently of the hedonic aspect. Moreover, we examined the hemodynamic responses to complex taste stimuli in food-based solutions and demonstrated for the first time that the complicated phenomenon of the "masking effect," which decreases taste intensity despite the additional taste components, can be successfully detected by near-infrared spectroscopy. In summary, this study is the first to demonstrate near-infrared spectroscopy as a novel tool for objectively evaluating complex sour taste properties in foods and drinks.

Bombesin-like peptide is present in duct cells in salivary glands: studies on normal and irradiated animals

Bombesin (BN) and its mammalian counterpart gastrin-releasing peptide act as neuroregulatory hormones and tissue-specific growth factors, and have been implicated as peripheral and central satiety-inducing agents. In the present study, the immunohistochemical expression of BN in submandibular, sublingual and parotid glands of rats was examined 10 days after 5 consecutive days with daily doses of 6–8 Gy irradiation. Radioimmunoassay (RIA) methods were also used. Immunoreactive granular structures were observed within duct cells of both controls and irradiated animals. In the parenchyma of irradiated animals, very few nerve fibres showing BN-like immunoreactivity were observed. The RIA analysis showed that the content of BN-like material significantly increased in submandibular and parotid glands in response to irradiation. The results suggest that mainly a non-neural form of BN is detected in the salivary glands in the immunohistochemical analysis. Thus, the immunohistochemical observations suggest that BN-like peptides may be present in the duct system, where they may be constituents of the saliva. The observations of an increase in BN content in response to irradiation are of interest as BN has mitogenic effects, may stimulate secretion and contributes to satiety.

VIP in the rat parotid gland in response to irradiation

In the present study, the immunohistochemical expression of vasoactive intestinal polypeptide (VIP) in the parotid gland of rats exposed to fractionated irradiation was examined. VIP concentration was analyzed by radioimmunoassay (RIA). Irradiation lead to a marked increase in the immunohistochemical expression of VIP in the innervation of the gland parenchyme. VIP-like immunoreactivity (LI) frequently coexisted with SP (substance P)-LI in these nerve fibers. The pattern of VIP-innervation in association with large ducts and blood vessel walls was unchanged. RIA analysis revealed a more than three-fold elevation in VIP content in the gland in response to irradiation. The increase in VIP immunoreaction and VIP content was seen at examination ten days after cessation of a five-day treatment with a total dose of 30–40 Gray. The upregulation of VIP may be related to changes in the production of neurotrophic factors and to an increased demand for a potentiation of secretagogue effects of SP.

Fluid and protein secretion from ferret submandibular and parotid glands in response to sympathetic nerve stimulation or administration of sympathomimetics.

Electrical stimulation of the sympathetic innervation evoked secretion of submandibular and parotid saliva. By changing the mode of stimulation from a continuous to an intermittent one the fluid response increased and glandular blood flow improved. The volumes from the submandibular glands were larger than those from the parotid glands and further, the protein concentration of submandibular saliva was higher than that of parotid saliva. Adrenaline, isoprenaline and phenylephrine evoked larger fluid responses from submandibular than from parotid glands. However, the fluid response was small compared to the parasympathetic one. Substance P-evoked saliva was used as carrier for protein released by sympathetic nerve stimulation or administration of adrenaline and isoprenaline. In vitro tissues of submandibular and parotid glands responded to adrenaline with a dose-dependent release of protein. Taken together, the analytical pharmacology performed in vivo and in vitro, and including the antagonists phentolamine, dihydroergotamine, propranolol and metoprolol, showed that in submandibular glands, alpha(alpha 1)adrenoceptors were predominantly involved in fluid secretion and beta(beta 1)-adrenoceptors predominantly involved in protein secretion. In parotid glands, fluid secretion seemed solely to depend on alpha(alpha 1)-adrenoceptors, while beta(beta 1)-adrenoceptors seemed almost solely involved in protein secretion.

Effect of EGF on rat parotid gland secretory function

The present study reports changes in saliva composition from the rat parotid gland in response to single and repeated administration of epidermal growth factor (EGF). Treatment of rats with EGF (10 μg/kg, i.p., twice daily for 3 days) caused an increase in amylase activity in saliva collected from cannulated parotid duct, following stimulation of secretion with pilocarpine, with a corresponding decrease in enzyme activity in the gland. Analysis of parotid gland RNA by reverse transcriptase-PCR generated a single predicted amylase-derived cDNA product of 576 bp. The steady-state levels of mRNA for amylase from EGF-treated parotid total RNA showed a 1.8-fold increase compared to untreated controls. A single dose of EGF (15 min following i.p. injection) elicited an activation of both protein kinase A and protein kinase C activities. While the activation of protein kinase A was still maintained under the chronic EGF regimen, the activity levels of protein kinase C showed down-regulation to untreated control values.

Influence of atropine on the depletion of vasoactive intestinal peptide, substance P and calcitonin gene‐related peptide from rat parotid gland in response to parasympathetic nerve stimulation

Influence of atropine on the depletion of vasoactive intestinal peptide, substance P and calcitonin gene‐related peptide from rat parotid gland in response to parasympathetic nerve stimulation

Differential regulation of gene expression in mouse parotid glands in response to isoprenaline treatment

Differential regulation of gene expression in mouse parotid glands in response to isoprenaline treatment

Age changes in secretory function of male and female rat parotid glands in response to methoxamine and pilocarpine.

Saliva secreted in response to methoxamine and pilocarpine was collected from the cannulated ducts of both parotid glands of male and female rats at weekly age intervals from three to 10 weeks, and at 3.5, 8, and 15 months of age. It was analyzed for the concentrations of protein, potassium, calcium, inorganic phosphate, and for amylase activity. The type of protein were determined electrophoretically, and an amino acid analysis of the total protein was also carried out. The wet weights of the glands increased substantially up to eight weeks of age, then reached almost plateau values, and finally tended to decrease at 15 months of age in both sexes. The salivary volumes secreted in response to methoxamine and pilocarpine were positively correlated with the parotid gland weights in both sexes. The concentrations of protein, potassium, and inorganic phosphate were inversely related to the salivary flow rates only at relatively low rates of flow. The amylase activity was positively correlated with the concentration of protein, independent of the nature of the stimulus, age, and sex. With methoxamine as a stimulus, the amylase activity was positively correlated with the concentration of calcium, independent of age and sex. The types of protein and amino acid concentrations were independent of the nature of the stimulus, age, and sex up to 15 months of age. However, in parotid saliva of several rats at 8 and 15 months of age, unusual proteins were observed electrophoretically, independent of the nature of the stimulus and sex.

Influence of circulating catecholamines on protein secretion into rat parotid saliva during parasympathetic stimulation.

Secretion of proteins by rat parotid glands in response to parasympathetic nerve stimulation was studied in vivo during pentobarbitone anaesthesia. Parasympathetic stimulation (3-10 Hz) via the auriculotemporal nerve resulted in a copious flow of saliva low in protein. In contrast, sympathetic stimulation (5 Hz) via the cervical sympathetic trunk evoked saliva low in volume but high in protein. Nevertheless, the specific concentrations of amylase and peroxidase (mg/mg protein) and the ratio of amylase to peroxidase remained constant. Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis revealed a single, rapidly migrating protein band of unknown identity in proportionately greater amounts in parasympathetic saliva than in sympathetic saliva. Bilateral adrenalectomy led to reduced amylase and peroxidase secretion in response to parasympathetic stimulation both on a mg/ml and a mg/mg protein basis. SDS gel electrophoresis also demonstrated the decrease in specific amylase concentration following adrenalectomy. The ratio of amylase to peroxidase, however, was not significantly affected. Administration of 6-hydroxydopamine 17-72 h prior to adrenalectomy caused no further reduction in the secretion of amylase and peroxidase. Chronic sympathectomy of 2.5-4 months duration resulted in an increased protein secretion (mg/ml) by the parotid gland in response to parasympathetic stimulation. This increase was only slightly reduced by bilateral adrenalectomy. However, as observed in non-sympathectomized rats, adrenalectomy caused a significant reduction in the specific concentrations of both amylase and peroxidase, but did not affect the amylase to peroxidase ratios. We conclude that parasympathetic nerve stimulation of rat parotid glands after overnight starvation causes secretion of proteins in proportions similar to, but in significantly lower concentrations than those found in sympathetic saliva. Circulating catecholamines, however, influence the amount of amylase and peroxidase secreted by the rat parotid gland in response to parasympathetic nerve stimulation and account for most of the increased secretion of these enzymes following chronic sympathectomy.

Secretion of saliva by human lip mucous glands and parotid glands in response to gustatory stimuli and chewing

To test the suggestion that minor salivary glands, such as the lower lip mucous glands, respond to stimulation in a similar manner to major glands such as the parotid, an appliance was constructed for each subject using an organopolysiloxane dental impression material which held a strip of filter paper against the inner aspect of the lower lip. The volume of labial secretion produced was determined by weight difference. Saliva from the right parotid duct was collected into pre-weighed tubes using a Lashley cannula. Test stimuli, applied for 4-min periods in triplicate, were ascorbic acid (0.08 and 0.16 M), sodium chloride (0.4 and 0.8 M) and the chewing of pieces of polyurethane foam and chicle. In 7 of 13 subjects, the response patterns of labial and parotid glands were qualitatively similar. With acid stimulation, the percentage increase in flow from the parotid was much greater than from labial glands. A significant difference was noted between the mean volumes of unstimulated secretion from the lip glands in a group of 8 subjects with restorations in lower anterior teeth and in 12 controls.

Cell-free translations of proline-rich protein mRNAs.

Treatment of rats with the beta-agonist isoproterenol causes a dramatic increase in a series of proteins rich in proline (proline-rich proteins) in the parotid glands (Muenzer, J., Bildstein, C., Gleason, M., and Carlson, D. M. (1979) J. Biol. Chem. 254, 5623, 5629). These proteins which contain about 43% proline, comprise more than 50% of the total soluble protein of glands of rats treated with isoproterenol for 10 days. Further studies by in vitro translation analysis using the reticulocyte lysate system and labeling with [3H]proline or [35S]methionine show definitive changes in patterns of protein synthesis and proline-rich protein mRNAs are highly elevated in treated animals. Analysis of translation products by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed (1) very little synthesis of proline-rich proteins from poly(A+) RNA of glands of normal rats, (2) poly(A+) RNA from glands of treated animals synthesize mainly proline-rich proteins, (3) translations with [3H]proline and [35S]methionine give identical labeling patterns from cell-free translations are all precipitated by antibodies to proline-rich proteins. At least six different proline-rich proteins are translated with poly(A+) mRNA from glands of treated animals. Each of these proteins is likely a translation product of a separate, specific mRNA. The dramatic changes in protein synthesis of rat parotid glands in response to isoproterenol treatment suggest to us that the parotid gland of the isoproterenol-treated rat is an excellent model system to study the overall responsiveness of gene expression to catecholamines.

Parasympathetically evoked parotid salivary secretion of chronically amitriptyline-treated rats.

Treatment of rats with amitriptyline for 4 weeks significantly decreased flow rate of saliva elicited from parotid glands in response to electrical stimulation of the parasympathetic innervation but did not alter calcium concentration of such saliva. The mechanism of the dissociation between flow rate and calcium concentration of parasympathetically evoked saliva induced by amitriptyline treatment remains to be explored, and may not involve an amitriptyline induced reduction in acetylcholine release.

Mediation of β-adrenergic stimulated amylase release from mouse parotid gland

Amylase released from mouse parotid fragments by the β-adrenergic agonist, isoproterenol, was associated with l) enhanced 45Ca ++ efflux and 2) a dependence on the extracellular Na + concentration. Monensin, a sodium ionophore, mimicked the effects of isoproterenol on 45Ca ++ efflux. In the absence of extracellular sodium isoproterenol and monensin failed to significantly release 45Ca ++. Complete inhibition of isoproterenol stimulated amylase release occurred when 75 per cent or greater of the extracellular Na + was replaced by sucrose; carbachol stimulated amylase release was not affected. Tetracaine (0.2 mM to 1.0 mM) inhibited both isoproterenol and carbachol stimulated amylase release and inhibited the 45Ca ++ uptake induced by carbachol. Monensin, a sodium ionophore, mimicked the effects of isoproterenol on amylase release; this effect was significantly reduced in the absence of extracellular Na +. It is proposed that a primary step in the release of amylase form mouse parotid gland in response to β-adrenergic stimulation is an increased influx of Na + followed by release of intracellularly stored calcium.

Calcium mediation of cholinergic-stimulated amylase release from mouse parotid gland

Amylase release from mouse parotid fragments was stimulated independently by cholinergic and beta-adrenergic agents. The cholinergic agonist, carbachol, significantly increased release of amylase only in Ca2+ containing medium whereas isoproterenol-stimulated amylase release was unaffected by Ca2+ removal. The ionophore, A23187, mimicked the effect of cholinergic stimulation when Ca2+ was present in the medium. Uptake of 45Ca2+ into tissue fragments was enhanced by carbachol and A23187 but not by isoproterenol; atropine blocked the effect of carbachol. Diphenylhydantoin (DPH) and verapamil partially inhibited carbachol-stimulated amylase release and 45Ca2+ uptake, whereas diazoxide potentiated these effects; in all cases there was good parallelism between 45Ca2+ uptake and amylase release. It was concluded that the primary step in the release of amylase from mouse parotid gland in response to cholinergic agents is an increased influx of Ca2+.

Ultrastructure of mitotic arrest induced by isoprenaline in rat parotid acinar cells.

ABSTRACT The mitotic arrest of acinar cells in the rat parotid gland in response to isoprenaline has been investigated at the ultrastructural level. The arrested cells were characterized by the presence of both centriole pairs at the cell centre, around which chromosomes formed an approximately spherical array. Microtubules radiated out from both centriole pairs, indicating that they were part of a bipolar system. The microtubule population included both non-kinetochore and kinetochore microtubules. Metaphase arrest appeared to be due to failure of the poles to separate, or to remain separated in the case of cells already in metaphase at the time of drug administration. This could be explained by the drug interfering with the ability of interpolar microtubules from opposite poles to interact with one another. The distribution of the chromosomes around the centrioles appears to depend on the presence of kinetochore microtubules, which are thought to act as tethers, either by themselves or in conjunction with non-kinetochore microtubules. It is suggested that tension is necessary between the kinetochores and poles to attain the arrest configuration. Chromosomes were observed in which both kinetochores had attached microtubules but whether or not they were linked to opposite poles remains to be investigated. Two types of arrested cell were distinguished by their content of secretory granules. Cells already in mitosis at the time of isoprenaline administration were not depleted by drug action, and during the period of arrest numerous large secretory granules were intermingled with the chromosomes. Those cells which entered mitosis after the drug was given were initially blocked in the G2 phase, during which time they were depleted of secretory granules. On entering mitosis, these cells possessed only small secretory granules, which were newly synthesized. In the metaphase-arrested state the small secretory granules were clustered around the centriolar complexes, demonstrating the presence of a poleward force operating on them. It is possible that the same force acts on the secretory granules in the first type of arrested cell, but because of the relatively large size of the granules, the clustering around the poles is not pronounced. The nature of the forces acting on the chromosomes and on the secretory granules is discussed. The functioning of these forces during the arrest state has to be considered in any general model for mitosis.

Secretory potentials in the cat parotid gland in response to methacholine chloride.

Secretory potentials in the cat parotid gland in response to methacholine chloride.

Discharge and restitution of secretory material in the rat parotid gland in response to isoproterenol.

The sequence of morphological events occurring during discharge and restitution of secretory material in the rat parotid in response to isoproterenol administration has been studied using the electron microscope. With the dose used, discharge of secretory granules began within 5 min following injection and was complete by 40 mim. Intracellular accumulation of normal-appearing secretory material became evident at 6 hours, and restitution of resting quantities of secretory material was achieved between 12 and 18 hours after injection. Cellular events occurring during secretory discharge and restitution are discussed.