Stress and Salivary Glands

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.

The anatomical pattern of ductal arborization in parotid glands using cone-beam computerized sialography

Cone-Beam Computed Tomography-Sialography (Sialo-CBCT) is used to demonstrate salivary ductal structure. This study aimed to conduct a volumetric analysis of the anatomical morphology of Normal-Appearing Glands (NAGs) in parotid sialo-CBCT. Our retrospective study included 14 parotid sialo-CBCT scans interpreted as NAGs in 11 patients with salivary gland impairment. The main duct length and width, as well as number and width of secondary and tertiary ducts were manually evaluated. We found that the main parotid duct showed an average width of 1.39 mm, 1.15 mm, and 0.98 mm, for the proximal, middle and distal thirds, respectively. The arborization pattern showed approximately 20% more tertiary (average number 11.1 ± 2.7) than secondary ducts (average number 9.0 ± 2.4) and approximately 8% narrower tertiary ducts (average width 0.65 ± 0.11 mm) compared to the secondary ducts (average width 0.77 ± 0.14 mm). Our anatomical analysis of NAGs in parotid sialo-CBCT demonstrated progressive narrowing of the main duct and increasing arborization and decreasing lumen size starting from the primary to the tertiary ducts. This is the most updated study regarding the anatomy of the parotid glands as demonstrated in sialo-CBCT. Our results may provide clinicians with the basic information for understanding aberration from normal morphology, as seen in salivary gland pathologies as well facilitate planning of treatment strategies, such as minimally invasive sialo-endoscopies, commonly practiced today.

Investigation of possible relationship between atopic dermatitis and salivary biomarkers, stress, and sleep disorders

Atopic dermatitis (AD) is a chronic, relapsing, multifactorial inflammatory disease with genetic, environmental, and immunological characteristics. The quality of life and sleep of patients and their families are affected by AD, which triggers stress, described as one of the factors that worsens AD. Salivary biomarkers such as cortisol, alpha-amylase, chromogranin A, and melatonin have been associated with stress and sleep disturbances. Therefore, the evaluation of stress and sleep disorders using salivary biomarkers in AD patients is important. This review aims to describe the possible relationship between atopic dermatitis and stress, sleep disorders, and salivary biomarkers, seeking to contribute to better understanding and clinical management of AD. This descriptive study is characterized as a narrative literature review. A literature search was conducted of studies published in English and Portuguese between January 2012 and October 2022 that are available in electronic media from various databases, such as Scientific Electronic Library Online, Latin American and Caribbean Literature on Health Sciences, and PubMed. AD is associated with different degrees of impact on the lives of individuals who present with the disease. Psychological stress may induce changes in saliva composition and worsen AD; at the same time, the severity of the disease may be associated with emotional impact. Further studies are needed to assess and correlate AD severity, stress, and sleep disturbances with salivary biomarkers in order to better understand this association.

Measuring Children's Stress via Saliva in Surgical and Endoscopic Procedures and Its Measurement Intention in the Community: Reality-Future Prospects

(1) Background: Children who undergo surgical or endoscopic procedures display high levels of stress, and various means are applied to reduce their anxiety. Salivary cortisol (S Cortisol) and salivary alpha-amylase (SAA) are often used as a valid biomarker of stress. The primary purpose of the study was the investigation of stress levels through S Cortisol and S amylase after intervention in surgical or endoscopic procedures (gastroscopy-colonoscopy). The secondary outcomes were the investigation of the intention to adopt new methods of saliva sampling. We collected saliva samples from children subjected to invasive medical procedures, with the aim of applying the Theory of Planned Behavior (TPB) as an intervention means to provide information and education to both parents and children undergoing stressful situations, and assess its efficacy in reducing stress levels. We also aimed at acquiring a better understanding of the acceptability of noninvasive biomarker collection in community settings. (2) Methods: The sample of this prospective study comprised 81 children who underwent surgical or endoscopic procedures at the Attikon General University Hospital, Athens, Greece and 90 parents. The sample was divided into two groups. The first, 'Group Unexplained', was not provided any information or education about the procedures, while the second, 'Group Explained', was informed and educated based on TPB. Thereafter, 8-10 weeks after intervention, the Theory of Planned Behavior questions were re-completed by the 'Group Explained'. (3) Results: Significant differences were detected in cortisol and amylase values between the two groups postoperatively after applying the TPB intervention. Saliva cortisol was reduced by 8.09 ng/mL in the 'Group Explained' while in the 'Group Unexplained' it was reduced by 4.45 ng/mL (p < 0.001). Salivary amylase values decreased by 9.69 ng/mL in the 'Group Explained' after the intervention phase of the study, while in the 'Group Unexplained' they increased by 35.04 ng/mL (p < 0.001). The regression explains 40.3% (baseline) and 28.5% (follow-up) of parental intention. The predictive factor of parental intention (baseline) is attitude (p < 0.001) and follow-up is behavioral control (p < 0.028) and attitude (p < 0.001). (4) Conclusions: Providing proper education and information for parents has a positive effect on reducing children's stress levels. Changing parental attitudes towards saliva collection plays the most important role, since a positive attitude can influence intention and ultimately participation in these procedures.

Structural changes and neurotrophic factors upregulation in submandibular gland in a rat model of depression: proposed correlation with stress indicators during and after the relief of depression

This study evaluated the structural changes, the immunohistochemical and gene expression of neurotrophic factors in submandibular gland in a rat model of depression, and their correlation with depression parameters during and after relief of depression by voluntary running. Forty-eight male Wistar rats were divided into control, control-exercise, depression, and depression-exercise groups. Depression was induced using forced swimming protocol, while the relief of depression was induced using the rat voluntary running wheels. The depressive state of rats was evaluated by measuring the immobility duration and the serum corticosterone level. The immune expression was evaluated by measuring the optical densities (ODs) using ImageJ software, and the gene expression levels were investigated. In the depression group, the convoluted ducts appeared dilated with numerous secretory granules. The number of PCNA-stained cells was significantly decreased in the depression group as compared to control group and then significantly increased in the depression-exercise group when compared to the depression group with a negative correlation to stress indicator. The ODs of immuno-expression for the brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) increased significantly in the depression group as compared to control group. Both BDNF and VEGF immuno-expression displayed positive correlation with the stress indicators. Both BDNF and VEGF gene expression results confirmed their immunohistochemical results. The findings of this study explored the role of submandibular gland in secreting neurotrophic factors and raise a flag for the possibility of using salivary secretions as dependable and easy parameter for estimation of chronic stressed patients.Mini AbstractThe submandibular gland neurotrophic factors immuno-expression can be used in estimating chronic depressive disorders as they are correlated with stress indicators during and after the relief of depression.

Dexmedetomidine premedication increases preoperative sedation and inhibits stress induced by tracheal intubation in adult: a prospective randomized double-blind clinical study

OBJECTIVE

The aim of this prospective randomized double-blind study is to evaluate whether oral dexmedetomidine (DEX) premedication could increase sedation in order to reduce preoperative anxiety and inhibit stress response during general anesthesia tracheal intubation.

MATERIALS

A total of 100 ASA I and II adult patients undergoing elective neurosurgery were randomly divided into the control group (C group, n = 50) and the oral DEX premedication (DEX group, n = 50). Patients were administrated 4 μg/kg dexmedetomidine orally pre-anesthesia 120 min. Hemodynamic variables were monitored and recorded from premedication to 10 min after tracheal intubation. The primary outcome, the sedation level of all participants, was evaluated by Richmond Agitation Sedation Scale (RASS), and Numerical Rating Scale was to measure their intensity of thirst and satisfaction of patients' family members. During general anesthesia induction, the total dosage of induction anesthetics and complications relative to anesthesia induction were recorded. After tracheal intubation, blood sample was drain from radial atrial line to measure levels of adrenocorticotropic hormone (ACTH) and cortisol.

RESULTS

RASS scores at 60 min after premedication and on arrival in the operating room were significantly reduced in the DEX group (P < 0.001). Oral DEX premedication not only increased the intensity of thirst but also the satisfaction of their family members (P < 0.001). The cortisol level after tracheal intubation was deduced by oral DEX premedication (P < 0.05). Oral DEX premedication reduced heart rate (HR) and mean arterial pressure (MAP) on arrival in the operating room, and HR when tracheal intubation (P < 0.05). During the whole process of anesthesia induction, although the lowest MAP in two groups were not significantly different, the lowest HR was significantly lower in the DEX group (P < 0.05). Oral DEX premedication might reduce HR from premedication to 10 min after tracheal intubation. However MAP was reduced just from premedication to on arrival in the operating room. Total induction dosages of propofol, midazolam, sulfentanil and rocuronium were similar in two groups (P > 0.05), as well as the complications relative to anesthesia induction and cases of rescue dopamine therapy were similar (P > 0.05).

CONCLUSION

Oral DEX 4 μg/kg premedication was an efficient intervention to increase preoperative sedation and reduce stress reaction induced by general anesthesia tracheal intubation, but also it was with the stable hemodynamic during the process of general anesthesia tracheal intubation, and improved the satisfaction of patients' family members. In this study, the sparing-anesthetic effect of 4 μg/kg DEX oral premedication was not significant, and this would be needed to study in future.

TRIAL REGISTRATION

This trail was registered at Chinese Clinical Trial Registry ( https://www.chictr.org.cn , Jie Gao) on 15/04/2021, registration number was ChiCTR2100045458.

Music in the relief of stress and distress in cancer patients

OBJECTIVES

to evaluate the effects of music on the physiological stress and distress of cancer patients being treated in a hospital.

METHODS

quasi-experimental study carried out with cancer patients hospitalized in the nursing wards of a public hospital. There was a single 15-minute intervention using music. It was individual, and headphones were used for patients to listen to three songs chosen by each one. The levels of stress and distress were measured before and after the intervention, using music to analyze the cortisol in the saliva and the answers to the distress thermometer. The significance level of the statistical analysis was 5%, using the non-parametric Wilcoxon test.

RESULTS

the mean age of the 26 patients was 56 years old. Most were female, white, and had breast cancer. After intervention, there were statistically significant diminutions in both stress and distress - p < 0.001.

CONCLUSIONS

the use of music diminishes the stress and the distress of cancer patients.

Impact of Sudarshan Kriya Yoga on Salivary pH: An Exploratory Pilot Study

INTRODUCTION

Saliva is increasingly used as a diagnostic tool as it is non-invasive, easily accessible, and less stressful compared to blood sampling. Saliva has a vital role in maintaining oral health. It is necessary for the salivary pH to be neutral in the oral cavity for the optimal functioning of its components. Stress has an effect on salivary pH.

OBJECTIVE

To study the effect of a mind-body intervention like Sudarshan Kriya yoga (SKY) on the salivary pH.

METHODS AND MATERIALS

An exploratory pilot study involving an open trial on 321 healthy individuals who were novice to SKY was conducted. The salivary pH was measured before and after a single 90-min session of SKY.

RESULTS

The salivary pH continued to be neutral after the intervention in the group that had initial neutral pH. There was a statistically significant shift of pH towards neutral in both the groups that had either acidic or alkaline pH initially.

CONCLUSION

Mind-body interventions like SKY modulate the salivary pH to bring it to the range of optimal functioning. This pilot study provides information for future long-term studies that can be implemented with measures of anxiety and stress along with measuring other salivary biomarkers.

Effects of Chlorine Dioxide on Oral Hygiene - A Systematic Review and Meta-analysis

Background

Effective and selective oral rinses are required in the daily medical and dental practice. Currently mouthwashes used have substantial side effects.

Objectives

Our aim was to evaluate the efficacy of chlorine dioxide-containing mouthwashes in comparison with other previously established mouth rinses in healthy adults using oral hygiene indices.

Methods

This work was registered in PROSPERO (CRD42018099059) and carried out using multiple databases and reported according to the PRISMA statement. The search terms used were “chlorine dioxide” AND “oral”, and only randomised controlled trials (RCTs) were included. The primary outcome was the alteration of the plaque index (PI), while the secondary outcomes were the gingival index (GI) and bacterial counts. For the risk of bias assessment, the Cochrane Risk of Bias Tool was used. Statistical analysis for data heterogeneity was performed by Q-value and I²-tests.

Results

364 articles were found in the databases. After the selection process, only five RCTs were eligible for meta-analysis. Data heterogeneity was low. There were no statistical differences in effectiveness between chlorine dioxide and other effective mouth rinses in PI (0.720±0.119 vs 0.745±0.131; 95%; confidence intervals (CIs): 0.487-0.952 vs 0.489-1.001, respectively) and GI (0.712±0.130 vs 0.745±0.131; 95% CIs: 0.457–0.967 vs 0.489–1.001, respectively) and also in bacterial counts.

Conclusion

Chlorine dioxide reduces both plaque and gingival indices and bacterial counts in the oral cavity similar to other routinely used oral rinses, however, the evidence supporting this outcome is very limited. Therefore, further large scale RCTs are needed to decrease the risk of bias.

Structural and posttranslational analysis of human calcium-binding protein, spermatid-associated 1

Recently, we detected a novel biomarker in human saliva called calcium-binding protein, spermatid-associated 1 (CABS1). CABS1 protein had previously been described only in testis, and little was known of its characteristics other than it was considered a structurally disordered protein. Levels of human CABS1 (hCABS1) in saliva correlate with stress, whereas smaller sized forms of hCABS1 in saliva are associated with resilience to stress. Interestingly, hCABS1 also has an anti-inflammatory peptide sequence near its carboxyl terminus, similar to that of a rat prohormone, submandibular rat 1. We performed phylogenetic and sequence analysis of hCABS1. We found that from 72 CABS1 sequences currently annotated in the National Center for Biotechnology Information protein database, only 14 contain the anti-inflammatory domain "TxIFELL," all of which are primates. We performed structural unfoldability analysis using PONDER and FoldIndex and discovered three domains that are highly disordered. Predictions of three-dimensional structure of hCABS1 using RaptorX, IonCom, and I-TASSER software agreed with these findings. Predicted neutrophil elastase cleavage density also correlated with hCABS1 regions of high structural disorder. Ligand binding prediction identified Ca2+ , Mg2+ , Zn2+ , leucine, and thiamine pyrophosphate, a pattern observed in enzymes associated with energy metabolism and mitochondrial localization. These new observations on hCABS1 raise intriguing questions about the interconnection between the autonomic nervous system, stress, and the immune system. However, the precise molecular mechanisms involved in the complex biology of hCABS1 remain unclear. We provide a detailed in silico analysis of relevant aspects of the structure and function of hCABS1 and postulate extracellular and intracellular roles.

Reliability of induced sputum test is greater than that of throat swab test for detecting SARS-CoV-2 in patients with COVID-19: A multi-center cross-sectional study

We previously reported that sputum induction was more sensitive than throat swabs for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in two convalescent coronavirus disease 2019 (COVID-19) patients; however, the value and safety of induced sputum testing require further study. We conducted a prospective multi-center cross-sectional study to compare induced sputum to throat swabs for SARS-CoV-2 detection. Confirmed COVID-19 patients from six hospitals in six cities across China who received one or more negative RT-PCR result for SARS-CoV-2 were enrolled, and paired specimens (induced sputum and throat swabs; 56 cases) were assayed. In three paired samples, both the induced sputum and throat swabs were positive for SARS-CoV-2. The positive rate for induced sputum was significantly higher than for throat swabs both overall (28.6% vs 5.4%, respectively; p < 0.01). Patients were divided according to time span from onset of illness to sample collection into the more-than-30-day (n = 26) and less-than-30-day (n = 30) groups. The positive rate for induced sputum was also significantly higher than for throat swabs in the less-than-30-day group (53.3% vs 10.0%, respectively; p < 0.001). For the more-than-30-day group, all paired samples were negative for SARS-CoV-2. Blood oxygen saturation, respiratory rate, and heart rate remained stable during sputum induction and no staff were infected. Because induced sputum is more reliable and has a lower false-negative rate than throat swabs, we believe induced sputum is more useful for the confirmation of COVID-19 and is safer as a criterion for release from quarantine.

Saliva as a Candidate for COVID-19 Diagnostic Testing: A Meta-Analysis

Background: COVID-19 is a serious and potentially deadly disease. Early diagnosis of infected individuals will play an important role in stopping its further escalation. The present gold standard for sampling is the nasopharyngeal swab method. However, several recent papers suggested that saliva-based testing is a promising alternative that could simplify and accelerate COVID-19 diagnosis. Objectives: Our aim was to conduct a meta-analysis on the reliability and consistency of SARS-CoV-2 viral RNA detection in saliva specimens. Methods: We have reported our meta-analysis according to the Cochrane Handbook. We searched the Cochrane Library, Embase, Pubmed, Scopus, Web of Science and clinical trial registries for eligible studies published between 1 January and 25 April 2020. The number of positive tests and the total number of tests conducted were collected as raw data. The proportion of positive tests in the pooled data were calculated by score confidence-interval estimation with the Freeman-Tukey transformation. Heterogeneity was assessed using the I 2 measure and the χ2-test. Results: The systematic search revealed 96 records after removal of duplicates. Twenty-six records were included for qualitative analysis and 5 records for quantitative synthesis. We found 91% (CI 80-99%) sensitivity for saliva tests and 98% (CI 89-100%) sensitivity for nasopharyngeal swab (NPS) tests in previously confirmed COVID-19 patients, with moderate heterogeneity among the studies. Additionally, we identified 18 registered, ongoing clinical trials of saliva-based tests for detection of the virus. Conclusion: Saliva tests offer a promising alternative to NPS for COVID-19 diagnosis. However, further diagnostic accuracy studies are needed to improve their specificity and sensitivity.

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.

Female Volleyball Players Are More Prone to Cortisol Anticipatory Stress Response than Sedentary Women

Background and Objectives: Top-level sports performance places heavy physical and psychological demands on elite-level athletes, which can be a source of increased levels of stress. Therefore, high-level volleyball players may present altered cardiovascular and endocrinological stress response during stressful events. Although many previous studies have examined the response to stress on athletes, most of them regarded only males, while the impact of the female menstrual cycle has rarely been taken into account. We aimed to study psychophysiological response to anticipatory stressor through analysis of heart rate, self-reported anxiety level, and salivary cortisol in healthy young female athletes by minimalizing the effect of confounders. Materials and Methods: A total of 55 females (25 members of the best league for female volleyball players in Poland and 30 sedentary-lifestyle control subjects) in the follicular phase of their menstrual cycle were exposed to mental arithmetic tasks as an experimental imitation of the stressor. Volleyball players were significantly taller than sedentary individuals (177.1 ± 3.4 cm vs. 173.3 ± 3.4 cm, respectively, p = 0.034), but did not differ in weight (73.6 ± 5.2 kg vs. 70 ± 4.23 kg, respectively, p = 0.081), body mass index (BMI) (23.5 ± 1.13 vs. 24.1 ± 1.45, respectively, p = 0.060), and age (22 ± 1.11 vs. 23 ± 1.14 years, respectively, p = 0.2). Their stress responses were assessed through self-reported anxiety levels and physiological measurements of salivary cortisol concentrations and heart rate (HR). Results: For HR, significant effects of time (F_(2,120) = 21.34, p < 0.001, η² = 0.26) were found, but not for training status (F_(1,60) = 2.69, p = 0.106, η² = 0.04). For cortisol levels, the analysis showed the main effects of time (F_(3,180) = 11.73, p < 0.001, η² = 0.16) and training status (F_(1,60) = 4.69, p = 0.034, η² = 0.07) and a significant interaction between training status and time (F_(3,180) = 3.07, p = 0.029, η² = 0.05). Post-hoc analyses showed higher cortisol concentrations among volleyball players following the math task (all p < 0.001), as well as higher cortisol concentrations in S2, S3, and S4 compared to S1 in volleyball players (all p < 0.001). We observed also a significant increase in state anxiety in both groups (all p < 0.001), but no differences in state anxiety levels between groups. Conclusion: Female volleyball players may not differ in subjective graduation of stressors; however, exposure to training-based stressors seems to promote cortisol response to the anticipated stressor.

Saliva and Blood Asprosin Hormone Concentration Associated with Obesity

BACKGROUND

The aim was to investigate the amounts of saliva and serum asprosin in order to determine whether it is related to obesity and whether salivary glands synthesize asprosin or not.

METHODS

A total of 116 underweight, normal weight, overweight, and obese (class I, class II, and class III) volunteers participated in the study. Saliva and blood samples were collected simultaneously from the participants. The amounts of asprosin in saliva, salivary gland tissue supernatants, and bloods were determined by ELISA, whereas asprosin synthesis sites of salivary gland tissues were determined immunohistochemically.

RESULTS

The amount of asprosin from the lowest to the highest was in the order as follows: underweight, normal weight (control), overweight, and obese classes I and III. The lowest level of asprosin was detected in underweight individuals. It was also found that the interlobular striated ducts and the interlobular ducts of the submandibular and parotid salivary glands produce asprosin. According to these data, the asprosin level is related with obesity as the amount increases in accordance with increasing body mass index (BMI). On the other hand, there is also a relationship between the underweight and asprosin because the amount decreases with BMI decrease.

CONCLUSIONS

Asprosin, a new adipokine, may be a novel indicator of adipose tissue mass. Therefore, we anticipate that antiasprosin preparations may be an alternative in the treatment of obesity in the future.

Hyperoxia reduces salivary secretion by inducing oxidative stress in mice

OBJECTIVE

The aim of this study was to determine the effects of prolonged hyperoxia on salivary glands and salivary secretion in mice.

DESIGN

Male C57BL/6 J mice were kept in a 75% oxygen chamber (hyperoxia group) or a 21% oxygen chamber for 5 days. We measured the secretion volume, protein concentration, and amylase activity of saliva after the injection of pilocarpine. In addition, we evaluated the histological changes induced in the submandibular glands using hematoxylin and eosin and Alcian blue staining and assessed apoptotic changes using the TdT-mediated dUTP nick end labeling (TUNEL) assay. We also compared the submandibular gland expression levels of heme oxygenase-1 (HO-1), superoxide dismutase (SOD)-1, and SOD-2 using the real-time polymerase chain reaction.

RESULTS

In the hyperoxia group, salivary secretion was significantly inhibited at 5 and 10 min after the injection of pilocarpine, and the total salivary secretion volume was significantly decreased. The salivary protein concentration and amylase activity were also significantly higher in the hyperoxia group. In the histological examinations, enlargement of the mucous acini and the accumulation of mucins were observed in the submandibular region in the hyperoxia group, and the number of TUNEL-positive cells was also significantly increased in the hyperoxia group. Moreover, the expression levels of HO-1, SOD-1, and SOD-2 were significantly higher in the hyperoxia group.

CONCLUSION

Our results suggest that hyperoxia reduces salivary secretion, and oxidative stress reactions might be involved in this.

Free and bound cortisol in plasma and saliva during ACTH challenge in dairy cows and horses

Cortisol levels reflect hypothalamic-pituitary-adrenocortical (HPA) axis activity. While most plasma cortisol is supposed to be bound to the soluble corticosteroid-binding globulin (CBG), only free cortisol (FC) actively regulates metabolic and immunological processes. We aimed to establish a multispecies suitable method to assess FC in cows and horses which in combination with total cortisol (TC) allows interpreting proportional changes of cortisol in saliva as well as in blood in response to a standardized HPA axis activation via ACTH. We further investigated if the ratios of cortisol fractions as obtained at basal levels in healthy horses (herbivorous and monogastric) and dairy cows (herbivorous and ruminant) change during HPA axis activation, and to which extent saliva cortisol (SC) is representative for alterations in plasma FC and adrenal cortex reactivity. However, it was not the objective of the present study to directly compare the two species. Dosages of ACTH applied in cows and horses were based on published data. Synthetic ACTH was intravenously administered to eight dairy cows (0.16 µg/kg BW) and five horses (1 µg/kg BW). Blood and saliva were collected every 30 min for 3 h from a jugular vein catheter, and analyzed for TC and SC, the ratio of free cortisol (rFC), and the concentration of FC (cFC) in plasma. During the entire sampling period of the ACTH test, plasma TC was paralleled by blood cFC, rFC, and SC in both cows and horses. All cortisol fractions increased within 30 min of ACTH administration compared to basal values (0 min, P < 0.05). Peak TC concentration reached 63.2 ± 9.6 ng/mL and 73.2 ± 11.8 ng/mL in bovine and equine plasma, respectively. Peak values of rFC averaged 17.9 ± 4.5% in cows and 19.2 ± 7.8% in horses. The ratio of SC to cFC in horses remained similar during the ACTH challenge suggesting that SC is recruited from plasma FC. However, SC increased less compared to plasma TC and FC during HPA axis activation in cows. In conclusion, the short-term activation of the HPA axis caused not only an elevation of TC, but also a similar increase of rFC in both species. SC closely reflected changes of FC in horses, but less accurately in cows. The concomitant evaluation of changes among cortisol fractions might give further indications on adaptation mechanisms in glucocorticoid regulation as well as differentiate cortisol-related health disorders.