Juri Saruta

Expression and Localization of Chromogranin A Gene and Protein in Human Submandibular Gland

Human saliva chromogranin A (CgA) is clinically promising as a psychological stress marker. However, expression of CgA is poorly understood in humans, although salivary gland localization of CgA in other mammals, such as rodents and horses, has been demonstrated. In the present study, we investigated the expression and localization of CgA in the human submandibular gland (HSG) using various methods. CgA was consistently localized in serous and ductal cells in HSG, as detected by immunohistochemistry and in situhybridization. Reactivity was stronger in serous cells than in ductal cells. In addition, strong immunoreactivity for CgA was observed in the saliva matrix of ductal cavities. Western blotting gave one significant immunoreactive band of 68 kDa in the adrenal gland, HSG and saliva. Finally, CgA was detected in secretory granules of serous and ductal cells by immunoelectron microscopy. In conclusion, CgA in humans is produced by HSG and secreted into saliva.

Allowing animals to bite reverses the effects of immobilization stress on hippocampal neurotrophin expression

Acute immobilization stress alters the expression of neurotrophins, including brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), in rat hippocampus. We found that biting may be associated with reduction of systemic stress responses. The purpose of this study was to examine whether neurotrophin expression in rat hippocampus is influenced by biting. Rats were exposed to immobilization stress for 2 h (stress group without biting) or biting for the latter half of 2-hour immobilization stress (biting group). Adrenocorticotropic hormone (ACTH) and corticosterone levels were markedly elevated in the stress group, while the increases in ACHT and corticosterone were suppressed in the biting group. Decreased BDNF mRNA and increased NT-3 mRNA expression in hippocampus were detected on real-time polymerase chain reaction (PCR) in the stress group. The decrease in BDNF mRNA under acute immobilization stress was recovered by biting. In addition, the magnitude of increase in NT-3 mRNA was decreased. No changes in expression of tyrosine receptor kinase B or C, the receptors for BDNF and NT-3, respectively, were observed in this model. These findings suggest that biting influences the alterations in neurotrophin levels induced by acute immobilization stress in rat hippocampus.

Submandibular Glands Contribute to Increases in Plasma BDNF Levels

Brain-derived neurotrophic factor (BDNF) promotes survival and differentiation of neural cells in the central and peripheral nervous systems. BDNF has been detected in plasma, but its source has not yet been established. Expression of BDNF mRNA has been identified in the submandibular glands when male rats are exposed to acute immobilization stress. In the present study, we investigated whether plasma BDNF is influenced by the submandibular glands in this model. Acute immobilization stress for 60 min significantly increased the level of plasma BDNF. However, plasma BDNF elevation was markedly suppressed in bilaterally sialoadenectomized rats. There were no significant differences between stressed (60 min) and non-stressed rats with respect to the BDNF mRNA expression in the hippocampus, heart, lung, liver, pancreas, or spleen, as determined by real-time polymerase chain-reaction. These findings suggest that the submandibular glands may be the primary source of plasma BDNF in conditions of acute immobilization stress.

Immobilization stress induces BDNF in rat submandibular glands.

Brain-derived neurotrophic factor (BDNF) promotes survival and differentiation of the cells of the central and peripheral nervous systems. BDNF has been identified in non-neural tissue, including the heart, lung, platelets, lymphocytes, and lacrimal glands. Immobilization stress modifies BDNF mRNA expression in some organs. The present study examines the effect of immobilization stress on BDNF, and its receptor TrkB, in male rat submandibular glands. Increased BDNF mRNA and protein expression were observed in duct cells as a result of immobilization stress, as demonstrated by real-time PCR, Western blot, immunohistochemistry, and analysis by microdissection. TrkB mRNA was not detected in salivary gland tissue, or oral or esophageal mucosa, by RT-PCR. Rat submandibular gland was thus identified as an organ which expresses BDNF. Furthermore, the results of this study suggest that increased salivary BDNF expression occurs following immobilization stress.

Physiological and environmental parameters associated with mass spectrometry-based salivary metabolomic profiles

Mass spectrometry (MS)-based metabolomic methods enable simultaneous profiling of hundreds of salivary metabolites, and may be useful to diagnose a wide range of diseases using saliva. However, few studies have evaluated the effects of physiological or environmental factors on salivary metabolomic profiles. Therefore, we used capillary electrophoresis-MS to analyze saliva metabolite profiles in 155 subjects with reasonable oral hygiene, and examined the effects of physiological and environmental factors on the metabolite profiles. Overall, 257 metabolites were identified and quantified. The global profiles and individual metabolites were evaluated by principle component analysis and univariate tests, respectively. Collection method, collection time, sex, body mass index, and smoking affected the global metabolite profiles. However, age also might contribute to the bias in sex and collection time. The profiles were relatively unaffected by other parameters, such as alcohol consumption and smoking, tooth brushing, or the use of medications or nutritional supplements. Temporomandibular joint disorders had relatively greater effects on salivary metabolites than other dental abnormalities (e.g., stomatitis, tooth alignment, and dental caries). These findings provide further insight into the diversity and stability of salivary metabolomic profiles, as well as the generalizability of disease-specific biomarkers.

Expression and Role of the BDNF Receptor-TrkB in Rat Adrenal Gland under Acute Immobilization Stress

We reported that plasma brain-derived neurotrophic factor (BDNF) was maximally elevated following a 60-min period of acute immobilization stress and that salivary glands were the main source of plasma BDNF under this stress condition. However, the expression pattern of the BDNF receptor, Tyrosine receptor kinase B (TrkB), under this condition has yet to be determined. We therefore investigated the effect of this stress on the expression level of TrkB in various rat organs using real-time PCR. No significant differences were found between controls and 60 min-stressed rats with respect to TrkB level in various organs. Only adrenal glands showed significantly increased TrkB mRNA levels after 60 min of stress. TrkB mRNA and protein were observed to localize in chromaffin cells. In addition, we investigated whether BDNF-TrkB interaction influences the release of stress hormones from PC12 cells, derived from chromaffin cells. Truncated receptor, TrkB-T1, was identified in PC12 cells using RT-PCR. Exposure of PC12 cells to BDNF induced the release of catecholamine. This BDNF-evoked release was totally blocked by administration of the K252a in which an inhibitor of Trk receptors. Thus, BDNF-TrkB interactions may modulate catecholamine release from adrenal chromaffin cells under acute stress conditions.

Chronic stress affects the expression of brain-derived neurotrophic factor in rat salivary glands

Plasma brain-derived neurotrophic factor (BDNF) levels are associated with several neural disorders. Previously, we reported that BDNF is produced from salivary glands under acute immobilization stress. Additionally, salivary glands are the origin of plasma BDNF during stress; however, the association between the expression of BDNF by the salivary glands under chronic stress conditions is not known. In the present study, we investigated whether plasma BDNF levels in chronic stress depend on the salivary glands. Expression of BDNF mRNA and protein were identified in the submandibular glands when male rats were exposed to chronic restraint stress (12 h daily for 22 days). Chronic stress significantly increased plasma BDNF concentration, as well as adrenocorticotropic hormone and corticosterone levels, but was not altered under chronic stress in bilaterally sialoadenectomized rats. Since chronic stress increases plasma BDNF levels in the sialoadenectomized rat model, the plasma BDNF level was not dependent on BDNF from the salivary glands. Although the salivary glands were the source of plasma BDNF in acute stress conditions in our previous study, it seems that that the increased BDNF expression in the salivary glands in chronic stress does not contribute importantly to the increased circulating BDNF level. The increased plasma BDNF levels may play important roles in homeostasis under stress conditions.

Association between saliva PSA and serum PSA in conditions with prostate adenocarcinoma

In recent years, saliva samples have attracted attention as specimens, which may be used for cancer diagnosis. Prostate-specific antigen (PSA) is the most useful tumor marker for prostate adenocarcinoma (PA). We examined whether there is an association between saliva PSA and serum PSA in patients with PA using enzyme-linked immunosorbent assay. Human subjects were classified into two groups: a low-serum PSA concentration group (n = 20) (<2.5 ng/mL) and a high-serum PSA concentration group with high risk of recurrence or metastasis (n = 11) (≤2.5 ng/mL). There were significant differences in saliva PSA concentration between these groups (p < 0.05). Saliva PSA concentration correlated very well with serum PSA concentration in the high-serum PSA concentration group (γ = 0.910, p < 0.001) using Spearman’s rank test, but no correlation in the low-serum PSA concentration group. This result suggests that saliva PSA is associated with blood PSA in patients with recurrent or metastatic PA and may, therefore, be a useful PA biomarker.

Expression and Localization of Brain-Derived Neurotrophic Factor (BDNF) mRNA and Protein in Human Submandibular Gland

Brain-derived neurotrophic factor (BDNF) promotes cell survival and differentiation in the central and peripheral nervous systems. Previously, we reported that BDNF is produced by salivary glands under acute immobilization stress in rats. However, expression of BDNF is poorly understood in humans, although salivary gland localization of BDNF in rodents has been demonstrated. In the present study, we investigated the expression and localization of BDNF in the human submandibular gland (HSG) using reverse transcription-polymerase chain reaction, western blot analysis, in situ hybridization (ISH), immunohistochemistry (IHC), and ELISA. BDNF was consistently localized in HSG serous and ductal cells, as detected by ISH and IHC, with reactivity being stronger in serous cells. In addition, immunoreactivity for BDNF was observed in the saliva matrix of ductal cavities. Western blotting detected one significant immunoreactive 14 kDa band in the HSG and saliva. Immunoreactivities for salivary BDNF measured by ELISA in humans were 40.76±4.83 pg/mL and 52.64±8.42 pg/mL, in men and women, respectively. Although salivary BDNF concentrations in females tended to be higher than in males, the concentrations were not significantly different. In conclusion, human salivary BDNF may originate from salivary glands, as the HSG appears to produce BDNF.

Clinical and biological correlates of resilience in patients with schizophrenia and bipolar disorder: A cross-sectional study.

OBJECTIVE The concept of resilience is relevant in understanding the heterogeneous outcomes noted in schizophrenia and bipolar disorder. However, clinical and biological correlates of resilience in these populations have rarely been investigated. We aimed to identify key correlates of subjective resilience in such patients using comprehensive assessments and to explore associations between resilience levels and peripheral biomarkers. METHOD 180 subjects with DSM-IV schizophrenia, bipolar disorder, and healthy controls (60 per group) were included. Demographic and clinical variables were assessed by means of interview and various psychometric scales. Furthermore, blood and saliva samples were obtained for the assessment of brain-derived neurotrophic factor, adrenocorticotropic hormone, cortisol, high sensitivity C-reactive protein, and alpha-amylase levels. Cross-sectional associations with resilience, as assessed by the 25-item Resilience Scale were sought. RESULTS Resilience Scale total scores were significantly higher in healthy individuals (130.1, 95% confidence intervals (CI): 124.8-135.4) compared to subjects with schizophrenia (109.9, 95% CI: 104.6-115.2, p<0.001) and bipolar disorder (119.0, 95% CI: 113.8-124.3, p=0.012), while the difference between patient groups was non-significant (p=0.055). Self-esteem, spirituality, quality of life, and hopelessness were correlated with resilience in all three groups. In addition, internalized stigma and depression were relevant factors in the schizophrenia and bipolar disorder group, respectively. Correlations between resilience levels and peripheral biomarkers did not reach significance. CONCLUSION Although causal relationships must be confirmed in prospective studies, our results have implications in developing psychological interventions to enhance resilience in patients with schizophrenia and bipolar disorder. The biological correlates of resilience in these populations warrant further investigations.