Regulation of salivary gland function by autonomic nerves

Dynamics of Salivary Gland AQP5 under Normal and Pathologic Conditions

AQP5 plays an important role in the salivary gland function. The mRNA and protein for aquaporin 5 (AQP5) are expressed in the acini from embryonic days E13-16 and E17-18, respectively and for entire postnatal days. Ligation-reopening of main excretory duct induces changes in the AQP5 level which would give an insight for mechanism of regeneration/self-duplication of acinar cells. The AQP5 level in the submandibular gland (SMG) decreases by chorda tympani denervation (CTD) via activation autophagosome, suggesting that its level in the SMG under normal condition is maintained by parasympathetic nerve. Isoproterenol (IPR), a β-adrenergic agonist, raised the levels of membrane AQP5 protein and its mRNA in the parotid gland (PG), suggesting coupling of the AQP5 dynamic and amylase secretion-restoration cycle. In the PG, lipopolysaccharide (LPS) is shown to activate mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signalings and potentially downregulate AQP5 expression via cross coupling of activator protein-1 (AP-1) and NF-κB. In most species, Ser-156 and Thr-259 of AQP5 are experimentally phosphorylated, which is enhanced by cAMP analogues and forskolin. cAMP-dependent phosphorylation of AQP5 does not seem to be markedly involved in regulation of its intracellular trafficking but seems to play a role in its constitutive expression and lateral diffusion in the cell membrane. Additionally, Ser-156 phosphorylation may be important for cancer development.

Xerostomia: prevention with Pycnogenol® supplementation: a pilot study

BACKGROUND

The aim of this pilot study was the evaluation of primary, idiopathic mucosal dryness (xerostomia or dry mouth) in subjects without cancer.

METHODS

A group of non-diabetic subjects and a group of diabetics were managed with standard management (SM) or with SM+Pycnogenol® (150 mg/day) for 2 weeks.

RESULTS

In total, 48 subjects were included in the study; 24 diabetics and 24 non-diabetics. 12 diabetics and 12 non-diabetics took Pycnogenol® and 12 diabetics and 12 non-diabetics were followed up with standard management only and served as controls. No side effects and no tolerability problems were observed with Pycnogenol®. The registry groups were comparable for characteristics and symptoms at baseline. All otherwise healthy subjects had a BMI<26 kg/m2. In 2 weeks, salivary flow and oxidative stress improved significantly in both groups of subjects (non-diabetics and diabetics) with 150 mg/day Pycnogenol® (P<0.05), while minimal improvements in salivary flow were seen with SM. The subjective score and the number of mucosal breaks and ulcerations, all minimal (<1 mm in length or diameter), were significantly decreased with Pycnogenol® supplementation (P<0.05) with minimal variations in the SM controls. Finally, the mean lysozyme level in parotid saliva samples was significantly increased in the Pycnogenol® group (P<0.05) both in diabetics and non-diabetics.

CONCLUSIONS

Based on these preliminary results, Pycnogenol® could be a new, valid option for the treatment of xerostomia.

Transcriptomic and Single-Cell Analysis of the Murine Parotid Gland

The salivary complex of mammals consists of 3 major pairs of glands: the parotid, submandibular, and sublingual glands. While the 3 glands share similar functional properties, such as saliva secretion, their differences are largely based on the types of secretions they produce. While recent studies have begun to shed light on the underlying molecular differences among the glands, few have examined the global transcriptional repertoire over various stages of gland maturation. To better elucidate the molecular nature of the parotid gland, we have performed RNA sequencing to generate comprehensive and global gene expression profiles of this gland at different stages of maturation. Our transcriptomic characterization and hierarchical clustering analysis with adult organ RNA sequencing data sets has identified a number of molecular players and pathways that are relevant for parotid gland biology. Moreover, our detailed analysis has revealed a unique parotid gland-specific gene signature that may represent important players that could impart parotid gland-specific biological properties. To complement our transcriptomic studies, we have performed single-cell RNA sequencing to map the transcriptomes of parotid epithelial cells. Interrogation of the single-cell transcriptomes revealed the degree of molecular and cellular heterogeneity of the various epithelial cell types within the parotid gland. Moreover, we uncovered a mixed-lineage population of cells that may reflect molecular priming of differentiation potentials. Overall our comprehensive studies provide a powerful tool for the discovery of novel molecular players important in parotid gland biology.

Proteome characterization of used nesting material and potential protein sources from group housed male mice, Mus musculus

Laboratory mice (Mus musculus) communicate a variety of social messages through olfactory cues and it is often speculated that these cues are preserved in nesting material. Based on these speculations, a growing number of husbandry recommendations support preserving used nests at cage cleaning to maintain familiar odors in the new cage. However, the content of used nesting material has never been chemically analyzed. Here we present the first comprehensive proteome profile of used nesting material. Nests from cages of group housed male mice contain a variety of proteins that primarily originate from saliva, plantar sweat, and urine sources. Most notably, a large proportion of proteins found in used nesting material belong to major urinary protein (“MUP”) and odorant binding protein (“OBP”) families. Both protein families send messages about individual identity and bind volatile compounds that further contribute to identity cues. Overall, this data supports current recommendations to preserve used nesting material at cage cleaning to maintain odor familiarity.

Submandibular gland botulinum neurotoxin A injection for predicting the outcome of submandibular duct relocation in drooling: a retrospective cohort study

AIM

This study evaluated whether the effect of submandibular gland botulinum neurotoxin A (BoNT-A) injection can predict the outcome of submandibular duct relocation with sublingual gland excision (SMDR) in children with drooling. Furthermore, we compared the effectiveness of both procedures.

METHOD

A retrospective cohort study was performed in 42 children and adolescents (25 males, 17 females; mean [SD] age at BoNT-A injection 11y [4], range 4-20y; mean [SD] age at SMDR 15y [4], range 7-23y) with cerebral palsy or another non-progressive developmental disability who had undergone both BoNT-A injection and SMDR for drooling. Main outcomes were the drooling quotient and the visual analogue scale (VAS) on drooling severity at 8 weeks and 32 weeks follow-up.

RESULTS

Failure or success of previous BoNT-A injections had no influence on success of consecutive SMDR. Relative change in main outcomes showed no significant relation between BoNT-A injection and SMDR for any follow-up measurement. After 8 weeks, SMDR was more successful than BoNT-A injection in diminishing VAS (VAS 80.0% vs 54.3%; drooling quotient 56.2% vs 51.0%). After 32 weeks, both drooling quotient (64.3% vs 29.5%) and VAS (75.7% vs 37.1%) showed significantly higher proportions of success for SMDR.

INTERPRETATION

The effect of submandibular BoNT-A injection does not predict subsequent SMDR success in drooling. Furthermore, SMDR has a larger and longer-lasting positive effect on drooling than BoNT-A injections.

WHAT THIS PAPER ADDS

Submandibular botulinum neurotoxin A (BoNT-A) injection effect does not predict submandibular duct relocation with sublingual gland excision outcome. Submandibular duct relocation is more effective and more permanent than BoNT-A injection.

Clinical implications of aberrant neurovascular structures coursing through the submandibular gland

Background

Variation within the submandibular triangle, including variant paths of facial neurovasculature, could increase risk of neurovascular derangement during submandibular gland (SMG) dysfunction, enlargement, interventions, or removal.

Methods

Frequency of anatomical variants enveloped within or piercing the SMG, including facial artery, vein, or branches of CN VII, were assessed in 70 cadaveric submandibular glands (39M/31F).

Results

Eighteen of 70 SMGs (25.7%) were pierced by at least one aberrant neurovasculature structure: Facial artery most frequently (n = 13), followed by facial vein (n = 2), inferior labial artery and vein (n = 1), and CN VII cervical branch (n = 1). This study demonstrated the high variability of neurovasculature within submandibular parenchyma. These aberrant neurovascular structures, especially facial artery, are in danger of compromise during surgical and other medical procedures on the SMG. To avoid potential neurovascular compromise, ultrasonographic or other imaging is recommended prior to procedures involving the SMG.

Dynamic photoacoustic imaging of neurovascular coupling in salivary glands

The purpose of this study was to apply photoacoustic imaging (PAI), a relatively new imaging method, to non-invasively map neurovascular dynamics in salivary glands. Dynamic PAI with co-registered ultrasound (US) was performed in mice to monitor salivary gland hemodynamics in response to exogenous muscarinic receptor stimulation (pilocarpine) and blockade (atropine). Pilocarpine increased salivary gland oxygen saturation (%sO₂) within minutes after administration, which was abrogated by atropine. A significant correlation was observed between change in %sO₂ measured by PAI and saliva secretion. PAI is a novel imaging method that can be used for functional assessment of neurovascular dynamics in salivary glands.

Transgenic rice seeds expressing altered peptide ligands against the M3 muscarinic acetylcholine receptor suppress experimental sialadenitis-like Sjögren's syndrome

Objective: We previously reported that Rag1^-/- mice inoculated with splenocytes from M3 muscarinic acetylcholine receptor (M3R) knockout mice immunized with an M3R peptide mixture developed sialadenitis-like Sjögren's syndrome (M3R-induced sialadenitis [MIS]). We also found that intravenous administration of altered peptide ligand (APL) of N-terminal 1 (N1), which is one of the T-cell epitopes of M3R, suppressed MIS. In this study, we aimed to evaluate the suppressive ability and its mechanisms of rice seeds expressing N1-APL7 against MIS.Methods: Rice seeds expressing N1 and N1-APL7 were orally administered to MIS mice for 2 weeks. The changes in saliva flow and sialadenitis (salivary gland inflammation) were analyzed. The M3R-specific T-cell response in the spleen and the expression of regulatory molecules in the cervical lymph nodes and mesenteric lymph nodes were also analyzed.Results: Oral administration of N1-APL7-expressing rice seeds significantly recovered reduction in saliva flow and suppressed sialadenitis when compared with treatment with nontransgenic rice seeds and N1 rice seeds. IFNγ production from M3R-reactive T cells tended to decline in the N1-APL7 rice-treated group as compared with those in the other groups. In the N1-APL7 rice-treated group, the mRNA expression levels of Foxp3 in the cervical-lymph-node CD4⁺ T cells were higher than those in the other groups.Conclusion: Oral administration of N1-APL7-expressing rice suppressed MIS via suppression of M3R-specific IFNγ and IL-17 production and via enhancement of regulatory molecule expression.Key messagesWe generated N1-peptide- or N1-APL7-expressing rice seeds. Oral administration of N1-APL7-expressing rice seeds significantly recovered the reduction of saliva flow and suppressed sialadenitis via the suppression of M3R specific IFNγ and IL-17 production and via enhancement of regulatory T (Treg) cells.

Electrical stimulation in the treatment of radiotherapy-induced hyposalivation

PURPOSE

To analyze the effects of electrical stimulation on the salivary flow of head and neck cancer patients with radiotherapy-induced hyposalivation.

RESEARCH STRATEGIES

Searches were made in the Medline (via Pubmed), Cochrane Library, Scopus and Lilacs databases.

SELECTION CRITERIA

Selection included clinical trials that evaluated salivary flow objectively, published in the last 10 years in either Portuguese, English or Spanish.

DATA ANALYSIS

The PEDro scale was used for the methodological evaluation of the studies.

RESULTS

The search strategy resulted in 21 publications, 17 of which were excluded, hence there were 4 articles left. The included studies had a total of 212 participants, all of whom had an increase in salivary flow, both through the electroacupuncture method and direct application on the salivary glands. The score obtained through the PEDRo scale was low, evidencing questionable methodological quality and risk of bias.

CONCLUSION

The included studies demonstrate the clinical potential of TENS to increase the salivary flow of head and neck cancer patients treated with RT.

Autonomic Abnormalities in Patients With Primary Sjogren's Syndrome - Preliminary Results

Primary Sjögren's syndrome (pSS) is an autoimmune disease affecting exocrine glands and extra-glandular organs. There are conflicting reports on the presence of autonomic dysfunction in pSS and no data are available on the functional status of sympathetic outflow to the vessels and baroreceptor [baroreflex sensitivity (BRS)] control mechanisms. We investigated the cardiac (cBRS) and sympathetic (sBRS) baroreceptor modulation in both time and frequency domains and the cardiovascular autonomic profile in pSS patients compared to healthy controls. Autonomic symptoms were quantified by the Composite Autonomic Symptom Scale (COMPASS31) three-item questionnaire. The EULAR Sjogren's syndrome patient reported index (ESSPRI) questionnaire evaluated the magnitude of pSS clinical symptoms, i.e., fatigue, pain, and sicca symptoms. Electrocardiogram, beat-by-beat arterial pressure (AP) and respiratory activity were continuously recorded in 17 pSS patients and 16 healthy controls, while supine and during 75° head-up tilt. In seven patients and seven controls, muscle sympathetic nerve activity (MSNA) was measured. Spectrum analysis of RR variability provided markers of cardiac vagal modulation (HF_RR nu) and sympatho-vagal balance [low frequency (LF)/high frequency (HF)]. The power of LF (0.1 Hz) oscillations of systolic arterial pressure (SAP) variability (LF_SAP) evaluated the vasomotor response to sympathetic stimulation. Compared to controls, pSS patients scored higher in total COMPASS31 (p < 0.0001) and all ESSPRI subdomains (fatigue, p = 0.005; pain, p = 0.0057; dryness, p < 0.0001). Abnormal scialometry (<1.5 ml/15 min) and Schirmer tests (<5 mm/5 min) were found in pSS patients and salivary flow rate was negatively associated with ESSPRI dryness (p = 0.0014). While supine, pSS patients had lower SEQ_cBRS index of cardiac baroreceptor sensitivity, higher HF_RRnu (p = 0.021), lower LF/HF (p = 0.007), and greater MSNA (p = 0.038) than controls. No differences were observed in LF_SAP between groups. During orthostatic challenge, although LF_SAP increased similarly in both groups, MSNA was greater in pSS patients (p = 0.003). At rest pSS patients showed lower cBR control and greater parasympathetic modulation. Furthermore, greater sympathetic nerve activity was observed in pSS patients while supine and in response to gravitational challenge. We hypothesized that such enhanced sympathetic vasoconstrictor activity might reflect an attempt to maintain blood pressure in a setting of likely reduced vascular responsiveness.

Physiology, Pathology and Regeneration of Salivary Glands

Salivary glands are essential structures in the oral cavity. A variety of diseases, such as cancer, autoimmune diseases, infections and physical traumas, can alter the functionality of these glands, greatly impacting the quality of life of patients. To date, no definitive therapeutic approach can compensate the impairment of salivary glands, and treatment are purely symptomatic. Understanding the cellular and molecular control of salivary glands function is, therefore, highly relevant for therapeutic purposes. In this review, we provide a starting platform for future studies in basic biology and clinical research, reporting classical ideas on salivary gland physiology and recently developed technology to guide regeneration, reconstruction and substitution of the functional organs.

A Salivation Abnormality with Trigeminal Nerve Dysfunction in Dogs

Trigeminal nerve pathology can lead to sensory and motor dysfunction to structures of the head that are easily recognized. The trigeminal nerve is a conduit for the distribution of postganglionic parasympathetic innervation to structures of the head. Parasympathetic innervation to the salivary glands is provided by preganglionic parasympathetic neurons of the facial and glossopharyngeal nerves. Postganglionic axons course with branches of the mandibular branch of the trigeminal nerve to reach the salivary glands. Denervation of the salivary glands impacts glandular function, leading to a reduction in the volume and composition of the saliva produced. Saliva plays an important role in oral health. Poor oral health has widespread systemic implications. This article describes a group of dogs with unilateral or bilateral dysfunction of the trigeminal nerve and/or its branches. In all dogs, an accumulation of thick, foamy saliva was observed accumulating in the dorsal aspect of the caudal oral cavity on the ipsilateral side to the affected nerve. In dogs with magnetic resonance imaging (MRI), there was a reduction in size based on the largest cross-sectional area measurement and an increase in mean signal intensity of the salivary glands ipsilateral to the affected nerves compared to the glands on the normal side. The authors hypothesize that the abnormal saliva and MRI changes observed were consequent to parasympathetic denervation of the salivary glands. The recognition of this clinical observation is the first step in understanding the impact that denervation has on salivation and ultimately on overall oral and systemic health in dogs.

Subjective unpleasantness of malodors induces a stress response

Unpleasant odors impair our mood and may affect physical health, even when the odorants are not toxic. A possible cause for such negative effects is stress induced by odors; however, whether the unpleasantness itself elicited stress or not has not been clear. Thus, we examined whether unpleasantness of odors induced the stress responses of emotion, the hypothalamic-pituitary-adrenal (HPA) axis, and the sympathetic nervous system (SNS). Six experiments were conducted, where salivary cortisol or salivary alpha amylase (sAA), markers for activities of the HPA and the SNS, respectively, were measured, along with subjective ratings of odors and emotion. First, the responses to three malodors listed in the Offensive Odor Control Law in Japan were examined. While these odors were rated as unpleasant, and exposure to them increased anxiety, no response of the HPA was observed (experiment 1, n = 69). In contrast, an increase of the SNS activity was observed after exposure to two of the three malodors, while the SNS did not respond to pleasant odors (experiments 2-4, n = 35, 34 and 30). To examine the effect of unpleasantness further, the SNS response was examined while subjective unpleasantness of odors was manipulated by adding negative verbal information (experiment 5, n = 92), or by mixing in a pleasant odor (experiment 6, n = 35). The SNS responses upon inhalation of the same odorous substances were found to be dependent on whether they were perceived as unpleasant. Finally, a correlation analysis on the pooled data from experiments 2-6 showed that the odor-elicited SNS activity and anxiety were strongly correlated with perceived unpleasantness of odors. These results suggest that subjective unpleasantness of odors per se can induce the stress response of emotion and the SNS.

Dual Sympathetic Input into Developing Salivary Glands

Neuronal signaling is known to be required for salivary gland development, with parasympathetic nerves interacting with the surrounding tissues from early stages to maintain a progenitor cell population and control morphogenesis. In contrast, postganglionic sympathetic nerves arrive late in salivary gland development to perform a secretory function; however, no previous report has shown their role during development. Here, we show that a subset of neuronal cells within the parasympathetic submandibular ganglion (PSG) express the catecholaminergic marker tyrosine hydroxylase (TH) in developing murine and human submandibular glands. This sympathetic phenotype coincided with the expression of transcription factor Hand2 within the PSG from the bud stage (E12.5) of mouse embryonic salivary gland development. Hand2 was previously associated with the decision of neural crest cells to become sympathetic in other systems, suggesting a role in controlling neuronal fate in the salivary gland. The PSG therefore provides a population of TH-expressing neurons prior to the arrival of the postganglionic sympathetic axons from the superior cervical ganglion at E15.5. In culture, in the absence of nerves from the superior cervical ganglion, these PSG-derived TH neurons were clearly evident forming a network around the gland. Chemical ablation of dopamine receptors in explant culture with the neurotoxin 6-hydroxydopamine at early stages of gland development resulted in specific loss of the TH-positive neurons from the PSG, and subsequent branching was inhibited. Taken altogether, these results highlight for the first time the detailed developmental time course of TH-expressing neurons during murine salivary gland development and suggest a role for these neurons in branching morphogenesis.

Dynamic polyhedral actomyosin lattices remodel micron-scale curved membranes during exocytosis in live mice

Actomyosin networks, the cell's major force production machineries, remodel cellular membranes during myriad dynamic processes^1,2 by assembling into various architectures with distinct force generation properties^3,4. While linear and branched actomyosin architectures are well characterized in cell-culture and cell-free systems³, it is not known how actin and myosin networks form and function to remodel membranes in complex three-dimensional mammalian tissues. Here, we use four-dimensional spinning-disc confocal microscopy with image deconvolution to acquire macromolecular-scale detail of dynamic actomyosin networks in exocrine glands of live mice. We address how actin and myosin organize around large membrane-bound secretory vesicles and generate the forces required to complete exocytosis^5-7. We find that actin and non-muscle myosin II (NMII) assemble into previously undescribed polyhedral-like lattices around the vesicle membrane. The NMII lattice comprises bipolar minifilaments^8-10 as well as non-canonical three-legged configurations. Using photobleaching and pharmacological perturbations in vivo, we show that actomyosin contractility and actin polymerization together push on the underlying vesicle membrane to overcome the energy barrier and complete exocytosis⁷. Our imaging approach thus unveils a force-generating actomyosin lattice that regulates secretion in the exocrine organs of live animals.

Implicit Affect and Autonomous Nervous System Reactions: A Review of Research Using the Implicit Positive and Negative Affect Test

In everyday life, affective processes occur spontaneously and typically go along with an automatic activation of action tendencies and physiological responses. Because self-reports of affect are also known to be biased by various factors, including deficits in introspection or impression management strategies, an indirect measure, the Implicit Positive and Negative Affect Test (IPANAT), was developed to assess implicit affect and to circumvent these difficulties. In this review, findings from neurobiological and clinical studies administering the IPANAT are revised, we focus on the link between implicit affect and psychophysiological reactions to affective stimuli and stressors. Specifically, implicit affect as measured by the IPANAT was found to predict cardiovascular, endocrine, and functional neuroimaging correlates of stress or fear beyond explicit affect. The present evidence strongly suggests the usage of implicit affect measures in future research on stress and psychopathology.

Anatomical stability of human fungiform papillae and relationship with oral perception measured by salivary response and intensity rating

Fungiform papillae house taste buds on the anterior dorsal tongue. Literature is inconclusive as to whether taste perception correlates with fungiform papillae density (FPD). Gustatory reflexes modulate the amount and composition of saliva subsequently produced, and thus may be a more physiologically objective measure of tastant-receptor interactions. Taste perception fluctuates with time but the stability of individual fungiform papillae is unclear. This study followed ten healthy volunteers longitudinally at baseline, one and six months. FPD, diameter and position were measured and participants rated intensity perception of sucrose, caffeine, menthol and capsaicin solutions. Salivary flow rate, protein concentration and relative changes in protein composition were measured following each tastant. FPD, diameter and position were unchanged at six months. FPD did not correlate with intensity rating for any taste. FPD did correlate with changes in salivary protein output following sucrose (ρ = 0.72, p = 0.02) and changes in levels of proline-rich protein and mucin 7 following capsaicin (ρ = 0.71, p = 0.02, ρ = 0.68, p = 0.04, respectively). These results suggest that over six months fungiform papillae are anatomically stable, playing a greater role in mediating the physiological salivary response to stimuli rather than determining the perceived intensity of taste.

Salivary Flow Alteration in Patients Undergoing Treatment for Schizophrenia: Disease-Drug-Target Gene/Protein Association Study for Side-effects

BACKGROUND

Salivary flow alteration (SA), is a known unwarranted effect of schizophrenic medications. It manifest either as reduced (xerostomia) or increased (sialorrhea) SA, among treated schizophrenic patients. It is believed that the SA is due to action of the drugs/disease process involving the muscarinic receptor-3 to process acetyl choline, the common neurotransmitter. The genetic mediation behind the SA in such patients remains largely unexplored. We aimed to address the same by using curated literary databases to identify such relationship, if any existed.

MATERIAL AND METHODS

Curated databases of Gene-Disease Association, www.DisGeNet.org and www.networkanalyst.ca were effectively used to identify the probable genes, strength of association and the drug-genes pathway that could be possibly be involved. The genes associated with schizophrenia and SA were analyzed in detail. Protein-Protein interaction (PPI) network proven experimentally in humans were used to identify the missing or unreported links.

RESULTS

In all 28 genes associated with schizophrenia were linked to SA. The genetic network of schizophrenia and xerostomia involved FGFR2 gene prominently and network module was statistically significant (P = 9.87*10-8) was achieved that had xerostomia as a node, while schizophrenia (P = 0.025) had statistical significance. Sialorrhea had no statistical significance (P = 0.555). When schizophrenia and sialorrhea connections were analyzed for genetic interaction, only gene GCH1 emerged. On combining the three disease entities, the association of TAC1 gene with sialorrhea was also identified. Using PPI, the coordination of CHRM3, TAC1 and GPRASP1 gene were identified. This network involved several genes that has significant influence on calcium signaling pathway (P = 7.74*10-16), cholingeric synapse(P = 6 × 10-4), salivary secretion(P = 4.38*10-3), endocytosis(P = 8.23*10-4), TGFβ signaling pathway(P = 0.0031), gap junction (P = 4.08*10-3) and glutamergic synapse(P = 6.4*10-3). The involvement of G-receptor signaling protein product, GNAQ was established.

DISCUSSION AND CONCLUSION

The possible genetic pathway of SA in schizophrenic patients are discussed in light of pharmacotherapeutics. Using the knowledge effectively would help to increase the quality of life of schizophrenic besides increasing the understanding to use saliva as a biomarker of prognosis of schizophrenia and its drug effects.

Long-term Pilocarpine Treatment Improves Salivary Flow in Irradiated Mice

Radiation therapy for head and neck cancer frequently causes salivary gland dysfunction. Pilocarpine is a clinically approved and effective drug that induces saliva secretion, thereby keeping the oral mucosa moist and reducing discomfort in patients, but the effect is transient. We expected that this drug also has beneficial long-term effects that maintain the integrity of salivary glands by reducing, for instance, apoptosis. Here, we examined the effects of long-term pilocarpine administration in irradiated mice. The results indicated that long-term pilocarpine administration significantly improved salivary flow in irradiated mice, suggesting the potential beneficial effects of long-term administration. To elucidate the underlying mechanism, we analyzed the histology, apoptosis, and proliferation of acinar cells, and the expression of functional membrane proteins such as transmembrane member 16A, aquaporin-5, and Na-K-Cl cotransporter. Long-term pilocarpine treatment seemed to decrease irradiation-induced apoptosis, although the change was not statistically significant. The present results indicated that long-term administration of pilocarpine has beneficial effects on salivary flow in irradiated mice, and suggested that long-term administration possibly decreases apoptosis in irradiated salivary glands.

[Role and mechanism of muscarinic acetylcholine receptor in the regulation of submandibular gland secretion]

Muscarinic acetylcholine receptors (mAChRs), including M1-M5 subtypes, are classic receptors in regulating water, ion, and solute transport in salivary gland. Our work focuses on the studies on the expression pattern and function of mAChR in the submandibular gland (SMG), and the underlying mechanism involved in the mAChR-regulated secretion, together with the effect of parasympathectomy on the salivary secretion. Microvascular autotransplantation of SMG into the temporal fossa provides a continuous and endogenous source of fluids, and is currently an effective method for treating severe keratoconjunctivitis sicca. By using RT-PCR, Western blotting, and immunofluorescence, our data demonstrated that the expression of M1 and M3 subtypes were decreased in latent period in rabbit SMG autotransplantation model, whereas carbachol stimulation promoted the salivary secretion, as well as M1 and M3 expressions. By contrast, mAChRs were hypersensitive in epiphora SMGs, whereas atropine gel and botulinum toxin A application significantly inhibited the hypersecretion in both animal models and patients. Furthermore, the possible intracellular signal molecules involved in the mAChR-modulated salivary secretion were explored. Activation of mAChR upregulated the expression of aquaporin 5 (AQP5), the main transporter that mediated water secretion through transcellular pathway, and led to AQP5 trafficking from lipid rafts to non-lipid microdomain. Extracellular signal-regulated kinase 1/2 (ERK1/2) was involved in the mAChR-regulated AQP5 content. mAChR activation also modulated the expression, distribution, and function of tight junction proteins, and increased paracellular permeability. ERK1/2/β-arrestin2/clathrin/ubiquitin signaling pathway was responsible for the mAChR-regulated downregulation of tight junction molecule claudin-4. Cytoskeleton filamentous actin (F-actin) was also involved in the distribution and barrier function of epithelial tight junctions. Besides, endothelial tight junctions were opened by mAChR agonist-evoked salivation in the mice. Furthermore, parasympathetic denervation increased resting salivary secretion in the long terminrats and minipigs. Taken together, our work demonstrated that mAChR regulated saliva secretion via transcellular and paracellular pathways in SMG epithelium as well as tight junction opening in SMG endothelium. Modulation of mAChR might be a promising strategy to ameliorate SMG dysfunction.

Tear Lactoferrin and Lysozyme as Clinically Relevant Biomarkers of Mucosal Immune Competence

Tears have attracted interest as a minimally-invasive biological fluid from which to assess biomarkers. Lactoferrin (Lf) and lysozyme (Lys) are abundant in the tear fluid and have antimicrobial properties. Since the eye is a portal for infection transmission, assessment of immune status at the ocular surface may be clinically relevant. Therefore, the aim of this series of studies was to investigate the tear fluid antimicrobial proteins (AMPs) Lf and Lys as biomarkers of mucosal immune status. To be considered biomarkers of interest, we would expect tear AMPs to respond to stressors known to perturb immunity but be robust to confounding variables, and to be lower in participants with heightened risk or incidence of illness. We investigated the relationship between tear AMPs and upper respiratory tract infection (URTI; study 1) as well as the response of tear AMPs to prolonged treadmill exercise (study 2) and dehydration (study 3). Study 1 was a prospective cohort study conducted during the common cold season whereas studies 2 and 3 used repeated-measures crossover designs. In study 1, tear Lys concentration (C) as well as tear AMP secretion rates (SRs) were lower in individuals who reported pathogen-confirmed URTI (n = 9) throughout the observation period than in healthy, pathogen-free controls (n = 17; Lys-C, P = 0.002, d = 0.85; Lys-SR, P < 0.001, d = 1.00; Lf-SR, P = 0.018, d = 0.66). Tear AMP secretion rates were also lower in contact lens wearers. In study 2, tear AMP SRs were 42-49% lower at 30 min-1 h post-exercise vs. pre-exercise (P < 0.001, d = 0.80-0.93). Finally, in study 3, tear AMPs were not influenced by dehydration, although tear AMP concentrations (but not secretion rates) displayed diurnal variation. We conclude that Lf and Lys have potential as biomarkers of mucosal immune competence; in particular, whether these markers are lower in infection-prone individuals warrants further investigation.

Patho-physiological and toxicological aspects of monosodium glutamate

Nowadays, the life-line of urban population has been formed by commercial foods due to industrialization, urbanization, and rapid increase in working class. Commercial foods are time and energy saving foods but it compromising the nutritional value of foods. The term adulteration refers to the deliberate addition of compound which is usually not present in food. These compounds are known as food additives or food adulterant. Monosodium Glutamate (MSG) is one of the most common food additives. Several studies revealed that MSG has toxic effect on fetal development/fetus, children's, adolescent, and adults. Physiological complication associated with MSG toxicity are hypertension, obesity, gastrointestinal tract troubles, and impairment of function of brain, nervous system, reproductive, and endocrine system. The effect of MSG depends upon its dose, route of administration and exposure time. Public awareness may play a major role in controlling the food adulteration by working in collaboration with National testing facilities to scrutinize each commercial food article from time to time. The aim of this review article is to highlight the deleterious impact of MSG on human health.

Localization of phospholipase C β3 in the major salivary glands of adult mice

Phospholipase C (PLC)β has a role in saliva secretion by controlling intracellular Ca²⁺via its product, IP₃. The present study was attempted to localize PLCβ isoforms in mouse salivary glands in situ. A single major band was detected for PLCβ3 in immunoblots of the parotid and sublingual glands (PG, SLG), while no such band was seen in the submandibular gland (SMG). No bands were detected for PLCβ1 or 4 in the three glands. In immuno-light microscopy of PG and SLG, substantial immunoreactivity for PLCβ3 was seen in the cytoplasm including the plasmalemma of almost all ductal cells, while no distinct immunoreactivity was discerned in most acinar cells except for sublingual demilune cells. Numerous ductal cells exhibited higher immunoreactivity for PLCβ3 in their apical/supranuclear cell domain including the plasmalemma than in the basal/infranuclear domain, indicating an apico-basal polarity. In immuno-gold electron microscopy of PG ducts and SLG ducts and demilunes, most gold particles were found in association with plasma membranes as well as various intracellular membranes, most of which formed small oblong or flattened vesicles and vacuoles. A few particles were seen without association with any membranous structures. The present finding supports the previous physio-pharmacological result that Ca²⁺-signaling proteins as well as initial intracellular Ca²⁺ changes occur in the apical cell domain including the plasma membranes of the exocrine cells.

The emerging role of cranial nerves in shaping craniofacial development

Organs and structures of the vertebrate head perform a plethora of tasks including visualization, digestion, vocalization/communication, auditory functions, and respiration in response to neuronal input. This input is primarily derived from afferent and efferent fibers of the cranial nerves (sensory and motor respectively) and efferent fibers of the cervical sympathetic trunk. Despite their essential contribution to the function and integration of processes necessary for survival, how organ innervation is established remains poorly understood. Furthermore, while it has been appreciated for some time that innervation of organs by cranial nerves is regulated in part by secreted factors and cell surface ligands expressed by those organs, whether nerves also regulate the development of facial organs is only beginning to be elucidated. This review will provide an overview of cranial nerve development in relation to the organs they innervate, and outline their known contributions to craniofacial development, thereby providing insight into how nerves may shape the organs they innervate during development. Throughout, the interaction between different cell and tissue types will be highlighted.

Physiological cAMP-elevating secretagogues differentially regulate fluid and protein secretions in mouse submandibular and sublingual glands

The mechanisms underlying the functional differences in sympathetic and parasympathetic regulation of the major salivary glands have received little attention. The acute effects of parasympathetic muscarinic (carbachol)-dependent and combined parasympathetic-dependent plus cAMP-dependent pathways on fluid secretion rates, ion composition, and protein content were assessed using a newly developed ex vivo preparation that allows the simultaneous perfusion of the mouse submandibular (SMGs) and sublingual glands (SLGs). Our results confirm that the muscarinic-dependent pathway accounts for the bulk of salivation in SMGs and SLGs, whereas costimulation with a cAMP-increasing agent (forskolin, isoproterenol, or vasoactive intestinal peptide) did not increase the flow rate. Costimulation with carbachol plus the β-adrenergic agonist isoproterenol decreased the concentration of NaCl and produced a substantial increase in the protein and Ca²⁺ content of SMG but not SLG saliva, consistent with a sparse sympathetic innervation of the SLGs. On the other hand, forskolin, which bypasses receptors to increase intracellular cAMP by directly activating the enzyme adenylate cyclase, enhanced the secretion of protein and Ca²⁺ by both the SMGs and SLGs. In contrast, isoproterenol and vasoactive intestinal peptide specifically stimulated protein secretion in SMG and SLG salivas, respectively. In summary, cAMP-dependent signaling does not play a major role in the stimulation of fluid secretion in SMGs and SLGs, whereas each cAMP-increasing agonist behaves differently in a gland-specific manner suggesting differential expression of G protein-coupled receptors in the epithelial cells of SMGs and SLGs.

Role of NAADP for calcium signaling in the salivary gland

Coordination of intracellular Ca²⁺ signaling in parotid acini is crucial for controlling the secretion of primary saliva. Previous work from our lab has demonstrated acidic-organelle Ca²⁺ release as a participant in agonist-evoked signaling dynamics of the parotid acinar cell. Furthermore, results implicated a potential role for the potent Ca²⁺ releasing second messenger NAADP in these events. The current study interrogated a direct role of NAADP for Ca²⁺ signaling in the parotid salivary gland acinar cell. Use of live-cell Ca²⁺ imaging, patch-clamp methods, and confocal microscopy revealed for the first time NAADP can evoke or enhance Ca²⁺ dynamics in parotid acini. These results were compared with pancreatic acini, a morphologically similar cell type previously shown to display NAADP-dependent Ca²⁺ signals. Findings presented here may be relevant in establishing new therapeutic targets for those suffering from xerostomia produced by hypofunctioning salivary glands.

Quantitative Analysis of Parotid Gland Secretion Function in Sjögren's Syndrome Patients with Dynamic Magnetic Resonance Sialography

Objective

To evaluate the secretory function of parotid glands by dynamic magnetic resonance (MR) sialography and determine the clinical performance of this technique in diagnosing and evaluating Sjögren's syndrome (SS) patients.

Materials and Methods

This study enrolled 29 healthy volunteers (25 women and 4 men; mean age, 34.8 ± 6.3 years; age range, 26–47 years) and 25 primary SS (pSS) patients (23 women and 2 men; mean age, 37.7 ± 7.9 years; age range, 25–50 years) with decreased secretory function. The volume of the parotid gland ducts was precisely measured for both groups at single pre- and 6 post-gustatory-stimulated phases. Time-dependent volume change ratio curves were generated, four parameters were derived from the curves: the slope of the increase in the first post-stimulation phase (slope_1st), the peak value, the time-to-peak, the total saliva secretion post-stimulation. All values were used to quantitatively evaluate the secretory function of the parotid gland. The repeated measurement analysis, Mann-Whitney U test and receiver operating characteristic curve were applied.

Results

Time-dependent volume change ratio curves demonstrated that there is a statistically significant difference between the two groups (F = 8.750; p = 0.005). A quickly increasing curve was shown in the volunteer group, whereas a slowly increasing curve was shown in the pSS patient group. The slope_1st, peak value and total saliva secretion post-stimulation of the patient group were significantly lower than those of the volunteer group (p = 0.005, p = 0.003, and p = 0.002, respectively). The time-to-peak between the two groups was not significantly different (p = 0.383). The slope_1st can be used as a discriminator to diagnose SS patients (p = 0.015; odds ratio = 4.234; area under the curve = 0.726).

Conclusion

Dynamic MR sialography is proven to be an effective method in evaluating salivary gland function and has a great potential in diagnosing and evaluating pSS patients.

GPR55 controls functional differentiation of self-renewing epithelial progenitors for salivation

GPR55, a lipid-sensing receptor, is implicated in cell cycle control, malignant cell mobilization, and tissue invasion in cancer. However, a physiological role for GPR55 is virtually unknown for any tissue type. Here, we localize GPR55 to self-renewing ductal epithelial cells and their terminally differentiated progeny in both human and mouse salivary glands. Moreover, we find GPR55 expression downregulated in salivary gland mucoepidermoid carcinomas and GPR55 reinstatement by antitumor irradiation, suggesting that GPR55 controls renegade proliferation. Indeed, GPR55 antagonism increases cell proliferation and function determination in quasiphysiological systems. In addition, Gpr55-/- mice present ~50% enlarged submandibular glands with many more granulated ducts, as well as disordered endoplasmic reticuli and with glycoprotein content. Next, we hypothesized that GPR55 could also modulate salivation and glycoprotein content by entraining differentiated excretory progeny. Accordingly, GPR55 activation facilitated glycoprotein release by itself, inducing low-amplitude Ca2+ oscillations, as well as enhancing acetylcholine-induced Ca2+ responses. Topical application of GPR55 agonists, which are ineffective in Gpr55-/- mice, into adult rodent submandibular glands increased salivation and saliva glycoprotein content. Overall, we propose that GPR55 signaling in epithelial cells ensures both the life-long renewal of ductal cells and the continuous availability of saliva and glycoproteins for oral health and food intake.

Heterogeneous localization of muscarinic cholinoceptor M1 in the salivary ducts of adult mice

We hypothesize variation in expression and localization, along the course of the glandular tubule, of muscarinic cholinergic receptor M₁ which plays as a distinct contribution, though minor in comparison with M₃ receptor, in saliva secretion. Localization of the M₁ receptor was examined using immunohistochemistry in three major salivary glands. Although all glandular cells were more or less M₁-immunoreactive, acinar cells were weakly immunoreactive, while ductal cells exhibited substantial M₁-immunoreactivity. Many ductal cells exhibited clear polarity with higher immunoreactivity in their apical/supra-nuclear domain. However, some exhibited indistinct polarity because of additional higher immunoreactivity in their basal/infra-nuclear domain. A small group of cells with intense immunoreactivity was found, mostly located in the intercalated ducts or in portions of the striated ducts close to the intercalated ducts. In immuno-electron microscopy, the immunoreactive materials were mainly in the cytoplasm including various vesicles and vacuoles. Unexpectedly, distinct immunoreactivity on apical and basal plasma membranes was infrequent in most ductal cells. The heterogeneous localization of M₁-immunoreactivity along the gland tubular system is discussed in view of possible modulatory roles of the M₁ receptor in saliva secretion.

MIST1, an Inductive Signal for Salivary Amylase in Mesenchymal Stem Cells

Sjögren’s syndrome (SjS) is an autoimmune disease that destroys the salivary glands and results in severe dry mouth. Mesenchymal stem cell (MSC) transplantation has been recently proposed as a promising therapy for restoring cells in multiple degenerative diseases. We have recently utilized advanced proteomics biochemical assays to identify the key molecules involved in the mesenchymal-epithelial transition (MET) of co-cultured mouse bone-marrow-derived MSCs mMSCs with primary salivary gland cells. Among the multiple transcription factors (TFs) that were differentially expressed, two major TFs were selected: muscle, intestine, and stomach expression-1 (MIST1) and transcription factor E2a (TCF3). These factors were assessed in the current study for their ability to drive the expression of acinar cell marker, alpha-salivary amylase 1 (AMY1), and ductal cell marker, cytokeratin19 (CK19), in vitro. Overexpression of MIST1-induced AMY1 expression while it had little effect on CK19 expression. In contrast, TCF3 induced neither of those cellular markers. Furthermore, we have identified that mMSCs express muscarinic-type 3 receptor (M3R) mainly in the cytoplasm and aquaporin 5 (AQP5) in the nucleus. While MIST1 did not alter M3R levels in mMSCs, a TCF3 overexpression downregulated M3R expressions in mMSCs. The mechanisms for such differential regulation of glandular markers by these TFs warrant further investigation.

Localization of phosphatidylinositol 4-phosphate 5-kinase (PIP5K) α, β, γ in the three major salivary glands in situ of mice and their response to β-adrenoceptor stimulation

Phosphatidylinositol 4-phosphate 5-kinase (PIP5K), which is composed of three isozymes (α, β and γ), catalyzes the production of phosphatidylinositol bisphosphate (PIP2). This phospholipid functions in membrane trafficking, as an anchor for actin cytoskeletons and as a regulator of intramembranous channels/transporters. It is also a precursor of such second messengers as diacylglycerol, inositol triphosphate and phosphatidylinositol (3,4,5)-triphosphate. In the present study, the expression and localization of endogenous PIP5Ks were examined in the three major salivary glands of young adult mice in situ. In western blotting of normal control glands, immunoreactive bands for individual PIP5Ks were detectable, with the highest density in the parotid gland and the weakest density in the submandibular gland. In immuno-light microscopy under non-stimulated condition, weak immunoreactivity for PIP5Kα was confined to the apical plasmalemma in parotid, but not sublingual or submandibular, acinar cells. Immunoreactivity for PIP5Kβ was weak to moderate and confined to ductal cells but not acinar cells, whereas that for PIP5Kγ was selectively and intensely detected in myoepithelial cells but not acinar cells, and it was weak in ductal cells in the three glands. In western blot of the parotid gland stimulated by isoproterenol, a β-adrenoceptor agonist, no changes were seen in the intensity of immunoreactive bands for any of the PIP5Ks. In contrast, in immuno-light microscopy, the apical immunoreactivity for PIP5Kα in parotid acinar cells was transiently and distinctly increased after the stimulation. The increased immunoreactivity was ultrastructurally localized on most apical microvilli and along contiguous plasma membrane, where membranous invaginations of various shapes and small vesicles were frequently found. It was thus suggested that PIP5Kα is involved in post-exocytotic membrane dynamics via microvillous membranes. The present finding further suggests that each of the three isoforms of PIP5K functions through its product PIP2 discretely in different cells of the glands to regulate saliva secretion.

Randomized controlled trial comparing botulinum vs surgery for drooling in neurodisabilities

OBJECTIVE

To compare the effect of submandibular duct ligation (2-DL) and submandibular botulinum neurotoxin type A (BoNT-A) for drooling in children and adolescents with neurodevelopmental disabilities.

METHODS

A randomized, interventional, controlled, and partly single-blinded study was performed in which submandibular BoNT-A was compared with 2-DL to treat excessive drooling. Main outcomes included a Visual Analog Scale (VAS), drooling quotient (DQ), drooling severity (DS) scale and drooling frequency (DF) scale. Each was obtained at baseline, and 8 and 32 weeks post treatment.

RESULTS

Fifty-seven patients (mean age: 11 years, mean baseline VAS score 7.9, mean baseline DQ 27.3%) were randomized to the 2-DL or BoNT-A group. Four patients were excluded from analyses, leaving 53 patients for intention-to-treat analyses. Response to treatment, defined as a ≥50% reduction in DQ or VAS score, was higher for 2-DL after 32 weeks (63.0% vs 26.9%, p = 0.008). Both VAS score (24.5, p < 0.001) and DQ (-9.3%, p = 0.022) were significantly lower at follow-up after 2-DL vs BoNT-A. The total number of adverse events (p = 0.088, 40.7% vs 19.2%) and postoperative complaints was higher (p < 0.001, mean 9.6 vs 3.6 days) for 2-DL than for BoNT-A.

CONCLUSION

The 2-DL procedure is a more effective treatment for drooling than botulinum toxin, but carries a slightly greater risk of complications and morbidity.

TRIALREGISTERNL IDENTIFIER

NTR3537.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for children and adolescents with neurodevelopmental disabilities and severe drooling, 2-DL compared to a one-time intraglandular BoNT-A injection is more effective at reducing drooling at 32 weeks.

Increased salivary fluid flow in children with newly diagnosed allergic rhinitis

OBJECTIVES

The pathogenesis of allergic rhinitis (AR) may involve dysregulation of the autonomic nervous system (ANS). Salivary fluid flow and salivary alpha-amylase (sAA) secretion are able to reflect the activity of parasympathetic (PNS) and sympathetic nervous system (SNS), respectively. The study aims to address the ANS profile in children with newly diagnosed AR by measuring the salivary secretion pattern.

METHODS

We recruited thirty-three children with newly diagnosed AR and thirty-one age- and sex-matched healthy children as control. Saliva samples were collected in the morning and the salivary parameters, including salivary flow rate (SFR, ml/min) and sAA secretion rate (μg/min), were determined accordingly. We also measured the gene copy number of the sAA gene, AMY1, for each individual.

RESULTS

We detected a significantly higher SFR in AR children compared with healthy control (2.20 ± 0.55 vs. 1.63 ± 0.61; p = 0.0002). Similar sAA secretion rate was observed between the two groups (312.8 ± 124.8 (Healthy) vs. 347.9 ± 114.0 (AR) μg/min; p = 0.2444). Besides, the two groups did not differ in AMY1 gene copy number (7.2 ± 2.3 (Healthy) vs. 7.7 ± 2.2 (AR); p = 0.3493).

CONCLUSIONS

Our results implicate an overactivity of the PNS while normal SNS activity in children with newly diagnosed AR. The findings support a contributing role of the ANS dysfunction in the pathogenesis of AR.

Exercise, Immunity, and Illness

It is generally accepted that moderate amounts of exercise improve immune system functions and hence reduce the risk of infection whereas athletes engaged in regular prolonged and/or intensive training have a higher than “normal” incidence of minor infections, especially of the upper respiratory tract (URT, e.g., common cold and influenza). This is likely related to regular acute (and possibly chronic) periods of exercise-induced changes in immune function. URT infections can compromise performance directly if suffered shortly before or during competition or indirectly if suffered at other times via effects on training and/or physiological adaptations. This chapter covers the effects of exercise (acute and chronic), both positive and negative, on immune function and consequent infection risk, and considers the current state-of-the-art for monitoring and assessing this in athletes.

Different immunohistochemical localization for TMEM16A and CFTR in acinar and ductal cells of rat major salivary glands and exocrine pancreas

We investigated the mRNA expression and immunohistochemical localization of Cl^- channels, transmembrane member 16A (TMEM16A or anoctamin 1), and cystic fibrosis transmembrane conductance regulator (CFTR) in rat major salivary glands and exocrine pancreas. RT-PCR detected mRNA expression of TMEM16A and CFTR in the extracts of the parotid gland (PG), submandibular gland (SMG), sublingual gland (SLG), and pancreas. Immunoreactivity for TMEM16A was localized in the apical membrane of serous acinar and intercalated ductal cells in the PG and SMG as well as mucous acinar cells in the SLG; however, it was not detected in striated ductal cells of these tissues. Although striated ductal cells in the PG, SMG and SLG, and granular ductal cells in the SMG, were immunoreactive for CFTR in the luminal side, serous, mucous acinar, and intercalated ductal cells were not immunoreactive for CFTR in any of the major salivary glands. In the exocrine pancreas, immunoreactivity for TMEM16A was localized in the apical membrane of acinar cells, while immunoreactivity for CFTR was localized in the luminal side of intercalated ductal cells. These results suggest that different localization of TMEM16A and CFTR immunoreactivities reflects the respective functions of acinar and ductal cells in major salivary glands and exocrine pancreas.

Influence of chewing on expression level of human beta-defensin 2 and secretory immunoglobulin A in the epithelium

PURPOSE

This study aimed to clarify the influence of chewing on human β-defensin 2 (hBD-2) and secretory immunoglobulin A (SIgA) expression levels.

METHODS

We included 15 healthy males with no missing teeth (mean age, 25.5±2.5years). Subjects were instructed to chew a piece of gum for 30min. Saliva and skin-extraction samples were collected before and after chewing for 15 and 30min. hBD-2 and SIgA concentrations in the samples were determined using enzyme-linked immunosorbent assay (ELISA). hBD-2 and SIgA expression levels before and after chewing were analyzed using the Mann-Whitney U test, following the Friedman test. The significance level was 0.05.

RESULTS

The hBD-2 level in skin-extraction samples was significantly different before (99.4±17.3pg/mL) and after chewing for 30min (142±23.0pg/mL). The SIgA level in skin-extraction samples was also significantly different before (2.39±0.25μg/mL) and after chewing for 30min (3.61±0.33μg/mL). No significant difference was noted in either hBD-2 or SIgA secretion rate in saliva between before and after chewing.

CONCLUSIONS

Chewing gum for 30min increased hBD-2 and SIgA expression levels in skin. Moreover, chewing gum could influence the secretion pattern of these two biomolecules on skin, but not in saliva.

Autonomic reactivity in blood-injection-injury and snake phobia

OBJECTIVE

This research aimed to study the salivary flow and other autonomic reactions -heart rate (HR) and skin conductance response (SCR)- in blood-injection-injury (BII) phobia and snake phobia participants, under the assumption that exposure to blood-related pictures in BII phobia will provoke an increase in parasympathetic activity that, in turn, will lead to a greater saliva production than other affective contents.

METHODS

We selected 18 BII phobia and 14 snake phobia participants along with 22 non-phobia individuals. All participants were exposed to 3 blocks of pictures (12 pictures per block) depicting either mutilations, snakes or neutral, household objects. Saliva samples were taken in the 2-min interval before and after each block.

RESULTS

In comparison to other contents, blood-related pictures provoked an increase in salivary flow in BII phobia participants, as well as an increase in the number of SCRs. In the snake phobia group, snake pictures provoked HR acceleration, but the SCRs they elicited did not differ from the SCRs provoked by the blood-related pictures.

CONCLUSION

BII phobia individuals react to their phobic object with a series of physiological changes resulting from a sympathetic-parasympathetic co-activation. This is in contrast with other specific phobias (e.g., small animal phobias) that usually show a sympathetically mediated, defensive reactivity when exposed to their disorder-relevant stimuli. These data support the use of therapeutic interventions in BII phobia that may differ in some respect from those used in other specific phobias.

Involvement of Aquaporins in the Pathogenesis, Diagnosis and Treatment of Sjögren's Syndrome

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of salivary and lacrimal glands resulting in diminished production of saliva and tears. The pathophysiology of SS has not yet been fully deciphered. Classically it has been postulated that sicca symptoms in SS patients are a double step process whereby lymphocytic infiltration of lacrimal and salivary glands (SG) is followed by epithelial cell destruction resulting in keratoconjunctivitis sicca and xerostomia. Recent advances in the field of the pathophysiology of SS have brought in new players, such as aquaporins (AQPs) and anti AQPs autoantibodies that could explain underlying mechanistic processes and unveil new pathophysiological pathways offering a deeper understanding of the disease. In this review, we delineate the link between the AQP and SS, focusing on salivary glands, and discuss the role of AQPs in the treatment of SS-induced xerostomia.

Switching to normal diet reverses kwashiorkor-induced salivary impairments via increased nitric oxide level and expression of aquaporin 5 in the submandibular glands of male Wistar rats

Kwashiorkor, a form of malnutrition, has been shown to cause impaired salivary secretion. However, there is dearth of information on the mechanism that underlies this complication. Also, whether returning to normal diet after kwashiorkor will reverse these complications or not is yet to be discerned. Thus, this study aimed at assessing the mechanisms that underlie kwashiorkor-induced salivary impairments and to evaluate the effects of switching back to normal-diet on kwashiorkor-induced salivary impairments. Weaning rats were randomly divided into 3 groups (control group, kwashiorkor group (KG), re-fed kwashiorkor group (RKG)) of 7 rats each. The control group had standard rat chow while the KG and RKG were fed 2% protein diet for 6 weeks to induce kwashiorkor. The RKG had their diet changed to standard rat-chow for another 6 weeks. Blood and stimulated saliva samples were collected for the analysis of total protein, electrolytes, amylase, immunoglobulin A (IgA) secretion rate, leptin, and ghrelin. Tissue total protein, nitric oxide level, expressions of Na⁺/K⁺-ATPase, muscarinic (M3) receptor, and aquaporin 5 in the submandibular glands were also determined. Data were presented as means ± SEM and compared using ANOVA with Tukey's post hoc test. RKG showed improved salivary function evidenced by reduced salivary lag-time and potassium and increased flow rate, sodium, amylase, IgA secretion rate, leptin, submandibular nitric oxide level, and aquaporin 5 expression compared with KG. This study for the first time demonstrated that kwashiorkor caused significant reduction in salivary secretion through reduction of nitric oxide level and aquaporin 5 expression in submandibular salivary glands. Normal-diet re-feeding after kwashiorkor returned salivary secretion to normal.

Effects of hyperleptinemia in rat saliva composition, histology and ultrastructure of the major salivary glands

OBJECTIVE

To study the effect of the satiety hormone, leptin, in saliva proteome and salivary gland histology and ultrastructure.

DESIGN

Increases in blood leptin levels were induced through mini-pump infusion in male Wistar rats, during a period of 7 days. Saliva was collected before and at the end of the experimental period, for proteomic analysis, and major salivary glands were collected, at the end, for biochemical, histological and ultrastructural analysis.

RESULTS

Immunohistochemistry revealed the presence of leptin receptors in major salivary glands. Salivary amylase levels and enzymatic activity were decreased in saliva, whereas the enzymatic activity of this protein was increased in the cytosol of parotid gland cells. Transmission electron microscopy allowed the observation of high number of electron-dense granules in cytosol of parotid acinar cells, from leptin treated animals.

CONCLUSIONS

Increased levels of plasmatic leptin result in changes in saliva composition and salivary glands function. To our knowledge, this is the first study providing evidences for a potential role of leptin in salivary gland secretion and saliva composition. An understanding of how appetite/satiety factors influence saliva composition and how this composition influences food processing in mouth may be relevant in understanding ingestivebehaviour.

Salivary secretion in health and disease

Saliva is a complex fluid produced by 3 pairs of major salivary glands and by hundreds of minor salivary glands. It comprises a large variety of constituents and physicochemical properties, which are important for the maintenance of oral health. Saliva not only protects the teeth and the oropharyngeal mucosa, it also facilitates articulation of speech, and is imperative for mastication and swallowing. Furthermore, saliva plays an important role in maintaining a balanced microbiota. Thus, the multiple functions provided by saliva are essential for proper protection and functioning of the body as a whole and for the general health. A large number of diseases and medications can affect salivary secretion through different mechanisms, leading to salivary gland dysfunction and associated oral problems, including xerostomia, dental caries and fungal infections. The first part of this review article provides an updated insight into our understanding of salivary gland structure, the neural regulation of salivary gland secretion, the mechanisms underlying the formation of saliva, the various functions of saliva and factors that influence salivary secretion under normal physiological conditions. The second part focuses on how various diseases and medical treatment including commonly prescribed medications and cancer therapies can affect salivary gland structure and function. We also provide a brief insight into how to diagnose salivary gland dysfunction.

Realising the Potential of Urine and Saliva as Diagnostic Tools in Sport and Exercise Medicine

Accurate monitoring of homeostatic perturbations following various psychophysiological stressors is essential in sports and exercise medicine. Various biomarkers are routinely used as monitoring tools in both clinical and elite sport settings. Blood collection and muscle biopsies, both invasive in nature, are considered the gold standard for the analysis of these biomarkers in exercise science. Exploring non-invasive methods of collecting and analysing biomarkers that are capable of providing accurate information regarding exercise-induced physiological and psychological stress is of obvious practical importance. This review describes the potential benefits, and the limitations, of using saliva and urine to ascertain biomarkers capable of identifying important stressors that are routinely encountered before, during, or after intense or unaccustomed exercise, competition, over-training, and inappropriate recovery. In particular, we focus on urinary and saliva biomarkers that have previously been used to monitor muscle damage, inflammation, cardiovascular stress, oxidative stress, hydration status, and brain distress. Evidence is provided from a range of empirical studies suggesting that urine and saliva are both capable of identifying various stressors. Although additional research regarding the efficacy of using urine and/or saliva to indicate the severity of exercise-induced psychophysiological stress is required, it is likely that these non-invasive biomarkers will represent "the future" in sports and exercise medicine.

Salivary functions in mastication, taste and textural perception, swallowing and initial digestion

Saliva exerts multiple functions in relation to the initial digestive processes taking place in the upper parts of the gastrointestinal tract. Ingestion of food and beverages, in turn, is a strong stimulus for secretion of saliva with a differential composition depending on the neuronal stimulation pattern. This review paper provides insight into the mechanisms by which saliva acts in relation to taste, mastication, bolus formation, enzymatic digestion and swallowing. Also, the protective functions of saliva including maintenance of dental and mucosal integrity will be discussed as they indirectly influence the digestive process. The final part of this study focuses on the implications of xerostomia and salivary gland dysfunction on gastrointestinal functions.

Altered Salivary Alpha-Amylase Secretion in Patients with Ulcerative Colitis

Purpose

Patients with ulcerative colitis (UC) frequently present with psychological disturbances as well as dysfunctions of autonomic nervous system (ANS). Salivary alpha-amylase (sAA) secretion is predominantly controlled by sympathetic nervous activity, while salivary fluid secretion is by parasympathetic nervous activity. Thus, it is speculated that alterations of salivary secretion may be addressed in UC populations.

Methods

Thirty-five UC patients as well as 32 age- and sex-matched healthy controls were enrolled. Saliva samples before and after citric acid stimulation were collected from each participant, and salivary flow rate (SFR) was calculated accordingly. Western blotting and quantitative PCR were applied to measure the sAA level and sAA gene (AMY1) copy number, respectively. The psychological disorders, anxiety and depression, were evaluated by the scoring system of Hospital Anxiety and Depression Scale (HADS) for each participant.

Results

We observed robustly increased prevalence of anxiety (p < 0.001) as well as depression (p < 0.001) in UC patients relative to controls. Interestingly, we detected elevated basal (p = 0.015) and stimulated (p = 0.021) sAA levels in the UC populations compared to controls. However, no differences were found for basal (p = 0.643) or stimulated (p = 0.402) SFR between the two study groups. Besides, AMY1 gene copy number was comparable between UC patients and controls.

Conclusions

Our results reveal an overactivity of the sympathetic nervous system and a normal activity of the parasympathetic nervous system in the UC population.