Development of Health-Promoting Edible Cricket Products by Using Sensory Evaluation Techniques.

BACKGROUND: In the fields of food science and technology, sensory evaluation is extensively studied to assess personal perception and acceptability. However, studies on Thai consumers' personal perceptions of and acceptability of food products containing crickets have not been conducted. OBJECTIVES: The overall goal of this study was to find out how well-liked two food products containing house crickets were by Thai customers in good health regarding their sensory qualities. METHODS: The 3-point Just-About-Right (JAR) scale measured the foods' sensory characteristics, including thickness, color, odor, sweetness, and saltiness. Food product approval among consumers was assessed using the 9-point Hedonic scale. Nutrient density was measured using the nutrient-rich foods (NRF) index, highlighting the potential health benefits of these products. RESULTS: For every attribute, the goodness-of-fit score of the cricket puffed rice (CPR) was higher than 70%. The cricket-galangal chili paste (CGCP) received a score of greater than 70% for color and odor, but the sweetness was required more since it had a JAR score of 53.3 percent. The customer acceptance scores of CPR and CGCP were 6.63-7.60 and 6.60-7.50 on the 9-point Hedonic scale. The NRF indices of the CPR and CGCP were 19.19 and 20.44 (intermediate levels). CONCLUSION: There was no need for improvements in the cricket puffed rice product, but cricket-galangal chili paste should be improved. Further study on nutrition facts is required.

Relationship Between Dietary Intakes and Elevated Diastolic Blood Pressure Among Children: A Cross-Sectional Study Using Wearable Devices.

BACKGROUND: Elevating systolic blood pressure (SBP) and diastolic blood pressure (DBP) independently influences clinical outcomes and adverse cardiovascular events. Blood pressure can be affected by modifiable (such as diets and physical activities) and non-modifiable factors (such as age and gender). Elevated blood pressure (EBP or formerly prehypertension) during childhood is associated with hypertension incidence in later adulthood. OBJECTIVES: This cross- sectional study investigated modifiable risk factors for blood pressure among children (aged 3-12). METHODS: We employed wearable devices to monitor the blood pressure of 45 preschool and primary school children and analyze this data with secondary blood pressure data of their parents from electronic medical records. RESULTS: EBP phenotypes in children (offspring) were not related to their parent's blood pressure phenotypes (P = 0.15 and 0.19 for SBP). Consumption of high saturated fat (P = 0.032), copper (P = 0.026), and vitamin B12 (P = 0.032) was associated with a significant increase in DBP. Daily sodium intakes between normal and DBP hypertensive groups were not significantly different (P = 0.75). CONCLUSION: This study indicates that dietary intakes of high saturated fat, copper, and vitamin B12, but not parental blood pressure statuses, determine high diastolic blood pressure among children regardless of daily sodium intake. Early dietary consumption behavioral adaptation should be considered to prevent further hypertension in adulthood.

Information Messages Related to Mental Health Status Among Caregivers in Rural of Thailand.

This cross-sectional study aimed to explore the Mental Health Status and the relationship between socioeconomic background and mean scores of mental health variables among Caregivers (CG) in Maha Sarakham province, Northeast of Thailand. A total of 402 CGs were recruited from 32 sub-districts in 13 districts to participate with interviewing form. Data analysing used descriptive statistics and Chi-square test for the relationship of the socioeconomic and the level of mental health status of caregivers. The results shown that; 99.77% were female, age average 49.89+8.14 (range 23-75), spent time look after the elderly for average 3 days per week, worked experience for 1-4 years (mean=3.27+1.66 years). Over 59 % have lower income than 150 USD. The gender of CG was a mainly statistically significant with the mental health status (MHS) (p=0.003). Although, the other variables were not significantly statistics test, however, it found that all variables indicated in the poor level of mental health status. Therefore, the stakeholders who involves with CG should have concern to reduce their burnout, regardless of compensation as well as set up the potential of family caregivers or young carers to help the elderly in the community.

Development of OSOMO Prompt Mobile Application on Elderly Population for Village Health Volunteers Using the Analysis, Design, Development, Implementation, and Evaluation (ADDIE) Model.

This paper aims to describe the use ADDIE model in developing a digital health tool, OSOMO Prompt app, and discuss evaluation outcomes of using this digital tool by village health volunteers (VHV) in rural areas in Thailand. The OSOMO prompt app was developed and implemented in elderly populations in eight rural areas. The Technology Acceptance Model (TAM) was used to test the acceptance of the app four month after the implementation. There were 601 VHVs voluntarily involved in the evaluation phase. The ADDIE model was successfully employed to guide the research team to develop the OSOMO Prompt app consisting of four services delivered to elderly populations by VHVs, including: 1) health assessment; 2) home visit; 3) knowledge management; and 4) emergency report. The findings from the evaluation phase reported that the OSOMO Prompt app was accepted as utility and simplicity (score 3.95+.62); and valuable digital tool (score 3.97+.68). The app received the highest score for being a useful tool assisting VHVs in achieving their work goals and improving work performance (score 4.0+.66). The OSOMO Prompt app could be modified for other healthcare services in different populations. Further investigation in long-term use and its impact on healthcare system is warranted.

Tooth Loss, Cognitive Impairment and Fall Risk: A Cross-Sectional Study of Older Adults in Rural Thailand.

Tooth loss is associated with both cognitive impairment and fall risk. However, the relationships between these variables are complex and bidirectional. Observed associations have been reported in separate studies but data on rural-dwelling older adults remain sparse. This cross-sectional study investigated socioeconomic and dental factors affecting cognitive functions, and the association between tooth loss, cognitive functioning, and fall risk. Two hundred and thirty-one rural-dwelling older adults (60−74 years old) were recruited from a single Dental Service Unit. Cognitive function and fall risk were assessed with the Mini-Mental State Examination and the Morse Fall Scale, respectively. Oral examinations were performed by a dentist using the Community Periodontal Index of Treatment Needs form. 38.1%, had >16 tooth loss. Socioeconomic data and health status were obtained from a questionnaire and interviews. Age, Activities of Daily Living (ADL) score, and the number of teeth lost was significantly associated with impaired cognitive function. Chi-square analysis showed that cognitive function was also associated with fall risk. Past research suggests that much cognitive impairment and fall risk is induced by tooth loss. Service planners need to be aware of the complex bidirectional relationships between these variables and give higher priority to dental services that can improve the general health status and social functioning of older rural adults.

Implementation of a Geographic Information System-Based Smartphone Application for Health Vigilance in Older Adults by Village Health Volunteers (OSOMO).

This paper mainly studies the smartphone application for health vigilance in elderly adults, based on geographic information system (GIS) for village health volunteers (OSOMO in Thai) to monitor elderly's health. Eight areas from 4 provinces of 7th health territory (Roi Et, Khon Kaen, Maha Sarakham, and Kalasin) were employed for research. The smartphone application called "OSOMO Prompt" was created for both iPhone (iOS) and Android devices for 1,246 OSOMOs. The comparison results of the difference of mean scores of knowledge of before and after using the "OSOMO Prompt" smartphone application, showed that the trial group, 240 elderly participants had the mean scores after smartphone application use of 1.69, higher than before use smartphone application. The results also indicated a statistically significant difference (p-value < .001) at 95%, confidence interval between 2.15-1.22. In conclusion, the "OSOMO Prompt" smartphone application was proved as a tool for village health volunteers to make health decision for the elderly persons. Moreover, the system was easy to use and could improve the quality of the elderly's healthcare.

Acceptability and Feasibility of Smart Phone Application "OSOMO Prompt" for Health Surveillance in Older Adults by Community Health Workers.

The magnanimous functionalities and flexibility of smartphone device make them well suited for collecting field data, especially for the local healthcare professional. This paper describes the results of the acceptability and feasibilityfor community health workers (CHWs) after using smartphone application called 'OSOMO prompt' app. The results indicated that the comparison of means of one sample t-test responses to the questions on the perceived usefulness and perceived ease of use of 'OSOMO prompt' app. The CHWs found that the high average scores of using the 'OSOMO prompt' app were useful in their job (mean=3.97±.68) and easy to use (Mean=3.95±.62). The app also had high score point of improving the quality of CHWs work, easy to do CHWs job, clearly and stability app while all items of perceived usefulness and perceived ease of use were statistical significantly (p-value <.001). In conclusion, challenging of smartphone 'OSOMO prompt' app was feasible and acceptable to CHWs.

Geographic Information System-Based Mobile Application Design for Health Care in Older Persons in Rural Community by Village Health Volunteers.

Health care for older persons is important for their well-being. In Thailand, village health volunteers (VHVs) play a crucial role in communicating between the older persons and health care professionals. Traditionally, they record and submit a monthly report as papers. This project was aimed to design a geographical information system (GIS)-based mobile application for health care in older persons in rural community by the VHVs. As a part of the analysis, design, development, implementation, and evaluation (ADDIE) model, health information obtained from 8,348 older persons and 1,125 VHVs living in rural community were analyzed and used for the for iPhone (iOS) and Android devices, and web browser. In summary, this mobile application allows the VHVs locate the older person's addresses and communicate with health care staff online in time-saving manner.

Association Between Physical Activity and Osteoarthritis of Knee with Quality of Life in Community-Dwelling Older Adults.

Older adults are relatively physically active compared to other age group. A lack of physical activity (PA) can cause chronic diseases including osteoarthritis of knee (OA knee) and might eventually reduce quality of life (QOL). This present study was aimed to investigate association between levels of PA and OA knee with levels of QOL in community-dwelling older adults. One thousand and sixty-seven community-dwelling older persons were recruited to this descriptive study. PA activity questionnaire was invented. Standardized Oxford knee score and World Health Organization's Quality of Life scale (WHOQOL-BREF) were used to measure OA knee and QOL levels. Results showed that levels of PA in older adults were significantly associated with levels of OKS (χ2 = 78.565, P-value < .001) and levels of OA knee in older adults were significantly associated with levels of overall QOL (χ2 = 57.738, P-value < .001). Pearson's correlation also showed interrelation among PA, OA knee, and QOL. In conclusion, PA, OA knee, and QOL are interrelated. Therefore, close monitoring and design of proper PA activity should be implemented in community-dwelling older adults with OA knee.

Psychological Stress Is a Risk Factor for Type 2 Diabetes Mellitus in College Students.

Type 2 diabetes mellitus (T2DM) is multifactorial disease. This cross-sectional study was aimed to investigate relationship between stress and risk for T2DM in college students. Seven-hundred participants (350 T2DM risk and 350 non-T2DM risk groups). Stress index levels and heart rate variability (HRV) were respectively measured as primary and secondary outcomes. Results showed that both T2DM-risk and non-T2DM-risk groups had temporary stress, but the T2DM-risk group had significantly higher level of psychological stress (P < .001). For the HRV, the T2DM-risk group had significantly lower levels of parasympathetic proxies (lnHF, SDNN, and RMSSD) (P < .001). Chi-square (χ2) test showed significant correlation of the stressful state with T2DM risk (χ2 = 159.372, P < .001, odds ratio (OR) = 9.326). In conclusion, psychological stress is a risk factor for T2DM in college students. Early detection, monitoring, and treatments of psychological stress should be implemented in this group of population.

Pesticides use and health impacts on farmers in Thailand, Vietnam, and Lao PDR: Protocol for a survey of knowledge, behaviours and blood acetyl cholinesterase concentrations.

Pesticides use in Southeast Asia has increased steadily, driven by the growth of large-scale commercial farming, as well as a desire to maximise food production in rural subsistence economies. Given that use of chemical pesticides, such as organophosphates and carbamates, has known potential health impacts, there are concerns about the safety of agricultural workers, and a need for a better evidence base to underpin regulation and worker education. This study, undertaken in 9 districts in Lao PDR, Thailand and Vietnam, will interview agricultural workers to investigate how they use pesticides, their knowledge of risks and self-protective practices, and their self-reported illness symptoms. In each district researchers will recruit and interview 120 participants engaged in vegetable farming, who have recently used pesticides, making a total of 1080 subjects divided equally between the three study countries. Workers' degree of pesticides exposure will be determined from acetyl cholinesterase concentrations in capillary blood samples collected using field test kits, and these data will be analysed together with the interview findings. Country findings will be compared and contrasted, and general patterns noted. Knowledge gained about risky behaviours, self-protective practices and degree of association with serious pesticides exposure will assist policy makers and inform health improvement programmes.

Risk and protective factors of relapse in patients with first-episode schizophrenia from perspectives of health professionals: a qualitative study in northeastern Thailand.

Background:  Schizophrenia is a serious mental illness that can relapse after treatments. Risk and protective factors for relapse are dependent on multicultural contexts. Objective: To identify risk and protective factors related to relapse in first-episode schizophrenia (FES) in northeastern Thailand from perspectives of health professionals. Methods: This qualitative research collected data from 21 health professional staff members (psychiatric nurses, psychiatrists, psychologists, social workers, occupational therapists and nutritionist) of a tertiary psychiatric hospital of northeastern Thailand who had been involved in mental health care for schizophrenia for at least 5 years by in-depth interviews and group interview using semi-structured interview schedule. Content analyses was used to identify staff perception of factors that put patients at risk of relapse. Results: Data analyses demonstrated that factors related to relapse in FES patients were drug adherence (drug discontinuation, limited access to new generation drugs, self-dose reduction and skipping medication, and poor insight), family factors (stressful circumstances and family supports), substance abuses (narcotics, addictive substances, caffeinated drinks), concurrent medical illness (insomnia, thyroid diseases, and pregnancy-related hormonal changes), and natural course of disease.  Conclusion: Factors affecting relapse in FES was not only drug adherence. Family factors, drug abuses, and concurrent health status should be also taken into account. A comprehensive mental health care program should be developed for FES patients in the region.

Thrombin receptor deficiency leads to a high bone mass phenotype by decreasing the RANKL/OPG ratio.

Thrombin and its receptor (TR) are, respectively, expressed in osteoclasts and osteoblasts. However, their physiological roles on bone metabolism have not been fully elucidated. Here we investigated the bone microarchitecture by micro-computed tomography (µCT) and demonstrated increased trabecular and cortical bone mass in femurs of TR KO mice compared to WT littermates. Trabecular thickness and connectivity were significantly enhanced. The physiological role of TR on both inorganic and organic phases of bone is illustrated by a significant increase in BMD and a decrease in urinary deoxypyridinoline (DPD) crosslink concentration in TR KO mice. Moreover, TR KO cortical bone expanded and had a higher polar moment of inertia (J), implying stronger bone. Bone histomorphometry illustrated unaltered osteoblast and osteoclast number and surface in femoral metaphyses, indicating that thrombin/TR regulates osteoblasts and osteoclasts at functional levels. Serum analysis showed a decrease in RANKL and an increase in osteoprotegerin (OPG) levels and reflected a reduced RANKL/OPG ratio in the TR KO group. In vitro experiments using MC3T3 pre-osteoblasts demonstrated a TR-dependent stimulatory effect of thrombin on the RANKL/OPG ratio. This effect was blocked by TR antagonist and p42/p44-ERK inhibitor. In addition, thrombin also intensified p42/p44-ERK expression and phosphorylation. In conclusion, the thrombin/TR system maintains normal bone remodeling by activating RANKL and limiting OPG synthesis by osteoblasts through the p42/44-ERK signaling pathway. Consequently, TR deficiency inhibits osteoclastogenesis, resulting in a high bone mass phenotype.

ß1-Adrenergic receptor signaling activates the epithelial calcium channel, transient receptor potential vanilloid type 5 (TRPV5), via the protein kinase A pathway.

Epinephrine and norepinephrine are present in the pro-urine. ß-Adrenergic receptor (ß-AR) blockers administered to counteract sympathetic overstimulation in patients with congestive heart failure have a negative inotropic effect, resulting in reduced cardiac contractility. Positive inotropes, ß1-AR agonists, are used to improve cardiac functions. Active Ca(2+) reabsorption in the late distal convoluted and connecting tubules (DCT2/CNT) is initiated by Ca(2+) influx through the transient receptor potential vanilloid type 5 (TRPV5) Ca(2+) channel. Although it was reported that ß-ARs are present in the DCT2/CNT region, their role in active Ca(2+) reabsorption remains elusive. Here we revealed that ß1-AR, but not ß2-AR, is localized with TRPV5 in DCT2/CNT. Subsequently, treatment of TRPV5-expressing mouse DCT2/CNT primary cell cultures with the ß1-AR agonist dobutamine showed enhanced apical-to-basolateral transepithelial Ca(2+) transport. In human embryonic kidney (HEK293) cells, dobutamine was shown to stimulate cAMP production, signifying functional ß1-AR expression. Fura-2 experiments demonstrated increased activity of TRPV5 in response to dobutamine, which could be prevented by the PKA inhibitor H89. Moreover, nonphosphorylable T709A-TRPV5 and phosphorylation-mimicking T709D-TRPV5 mutants were unresponsive to dobutamine. Surface biotinylation showed that dobutamine did not affect plasma membrane abundance of TRPV5. In conclusion, activation of ß1-AR stimulates active Ca(2+) reabsorption in DCT2/CNT; an increase in TRPV5 activity via PKA phosphorylation of residue Thr-709 possibly plays an important role. These data explicate a calciotropic role in addition to the inotropic property of ß1-AR.

Urinary plasmin inhibits TRPV5 in nephrotic-range proteinuria.

Urinary proteins that leak through the abnormal glomerulus in nephrotic syndrome may affect tubular transport by interacting with membrane transporters on the luminal side of tubular epithelial cells. Patients with nephrotic syndrome can develop nephrocalcinosis, which animal models suggest may develop from impaired transcellular Ca(2+) reabsorption via TRPV5 in the distal convoluted tubule (DCT). In nephrotic-range proteinuria, filtered plasminogen reaches the luminal side of DCT, where it is cleaved into active plasmin by urokinase. In this study, we found that plasmin purified from the urine of patients with nephrotic-range proteinuria inhibits Ca(2+) uptake in TRPV5-expressing human embryonic kidney 293 cells through the activation of protease-activated receptor-1 (PAR-1). Preincubation with a plasmin inhibitor, a PAR-1 antagonist, or a protein kinase C (PKC) inhibitor abolished the effect of plasmin on TRPV5. In addition, ablation of the PKC phosphorylation site S144 rendered TRPV5 resistant to the action of plasmin. Patch-clamp experiments showed that a decreased TRPV5 pore size and a reduced open probability accompany the plasmin-mediated reduction in Ca(2+) uptake. Furthermore, high-resolution nuclear magnetic resonance spectroscopy demonstrated specific interactions between calmodulin and residues 133-154 of the N-terminus of TRPV5 for both wild-type and phosphorylated (S144pS) peptides. In summary, PAR-1 activation by plasmin induces PKC-mediated phosphorylation of TRPV5, thereby altering calmodulin-TRPV5 binding, resulting in decreased channel activity. These results indicate that urinary plasmin could contribute to the downstream effects of proteinuria on the tubulointerstitium by negatively modulating TRPV5.

A primary culture of distal convoluted tubules expressing functional thiazide-sensitive NaCl transport.

Studying the molecular regulation of the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC) is important for understanding how the kidney contributes to blood pressure regulation. Until now, a native mammalian cell model to investigate this transporter remained unknown. Our aim here is to establish, for the first time, a primary distal convoluted tubule (DCT) cell culture exhibiting transcellular thiazide-sensitive Na(+) transport. Because parvalbumin (PV) is primarily expressed in the DCT, where it colocalizes with NCC, kidneys from mice expressing enhanced green-fluorescent protein (eGFP) under the PV gene promoter (PV-eGFP-mice) were employed. The Complex Object Parametric Analyzer and Sorter (COPAS) was used to sort fluorescent PV-positive tubules from these kidneys, which were then seeded onto permeable supports. After 6 days, DCT cell monolayers developed transepithelial resistance values of 630 ± 33 Ω·cm(2). The monolayers also established opposing transcellular concentration gradients of Na(+) and K(+). Radioactive (22)Na(+) flux experiments showed a net apical-to-basolateral thiazide-sensitive Na(+) transport across the monolayers. Both hypotonic low-chloride medium and 1 µM angiotensin II increased this (22)Na(+) transport significantly by four times, which could be totally blocked by 100 µM hydrochlorothiazide. Angiotensin II-stimulated (22)Na(+) transport was also inhibited by 1 µM losartan. Furthermore, NCC present in the DCT monolayers was detected by immunoblot and immunocytochemistry studies. In conclusion, a murine primary DCT culture was established which expresses functional thiazide-sensitive Na(+)-Cl(-) transport.

Tissue transglutaminase inhibits the TRPV5-dependent calcium transport in an N-glycosylation-dependent manner.

Tissue transglutaminase (tTG) is a multifunctional Ca(2+)-dependent enzyme, catalyzing protein crosslinking. The transient receptor potential vanilloid (TRPV) family of cation channels was recently shown to contribute to the regulation of TG activities in keratinocytes and hence skin barrier formation. In kidney, where active transcellular Ca(2+) transport via TRPV5 predominates, the potential effect of tTG remains unknown. A multitude of factors regulate TRPV5, many secreted into the pro-urine and acting from the extracellular side. We detected tTG in mouse urine and in the apical medium of polarized cultures of rabbit connecting tubule and cortical collecting duct (CNT/CCD) cells. Extracellular application of tTG significantly reduced TRPV5 activity in human embryonic kidney cells transiently expressing the channel. Similarly, a strong inhibition of transepithelial Ca(2+) transport was observed after apical application of purified tTG to polarized rabbit CNT/CCD cells. Furthermore, tTG promoted the aggregation of the plasma membrane-associated fraction of TRPV5. Using patch clamp analysis, we observed a reduction in the pore diameter after tTG treatment, suggesting distinct structural changes in TRPV5 upon crosslinking by tTG. As N-linked glycosylation of TRPV5 is a key step in regulating channel function, we determined the effect of tTG in the N-glycosylation-deficient TRPV5 mutant. In the absence of N-linked glycosylation, TRPV5 was insensitive to tTG. Taken together, these observations imply that tTG is a novel extracellular enzyme inhibiting the activity of TRPV5. The inhibition of TRPV5 occurs in an N-glycosylation-dependent manner, signifying a common final pathway by which distinct extracellular factors regulate channel activity.

1,25-dihydroxyvitamin D(3) rapidly stimulates the solvent drag-induced paracellular calcium transport in the duodenum of female rats.

A calcium-regulating hormone 1alpha,25-dihydroxyvitamin D(3) (1,25-[OH](2)D(3)) has been known to rapidly stimulate the transcellular active calcium transport in the chick duodenum. However, its effects on the solvent drag-induced paracellular calcium transport, which normally contributes approximately 70% of the total active calcium transport, and the underlying mechanism were unknown. The present study aimed to investigate the rapid nongenomic actions of physiological concentrations of 1,25-(OH)(2)D(3), i.e., 1, 10, and 100 nmol/l, on the duodenal calcium absorption in female rats. Quantitative real-time PCR revealed strong expressions of the classical vitamin D receptor (VDR) and the membrane-associated rapid response steroid binding receptors (MARRS) in both small and large intestines. By using the Ussing chamber technique, we found that duodenal epithelia acutely exposed to 10 and 100 nmol/l 1,25-(OH)(2)D(3) rapidly increased the solvent drag-induced calcium transport, but not the transcellular calcium transport, in a dose-response manner. On the other hand, 3-day daily injections of 1,25-(OH)(2)D(3) enhanced the transcellular active duodenal calcium transport. The 1,25-(OH)(2)D(3)-stimulated solvent drag-induced transport was abolished by the phosphatidylinositol 3-kinase (PI3K) inhibitors, 200 nmol/l wortmannin and 75 micromol/l LY294002, as well as PKC (1 micromol/l GF109203X) and MEK inhibitors (10 micromol/l U0126). Although 100 nmol/l 1,25-(OH)(2)D(3) did not alter the transepithelial mannitol flux, indicating no widening of the tight junction, it decreased the transepithelial resistance and increased both sodium and chloride permeability through the paracellular channel. We conclude that 1,25-(OH)(2)D(3) uses the nongenomic signaling pathways involving PI3K, PKC, and MEK to rapidly enhance the solvent drag-induced calcium transport, partly by altering the charge-selective property of the duodenal epithelium at least for the pathways involving PI3K and MEK.

Osteoblasts express claudins and tight junction-associated proteins.

Osteoblasts were previously reported to form tight junctions, which may play an important role in the regulation of ion transport across the epithelial-like bone membrane. However, the evidence for the presence of tight junction-associated proteins in osteoblasts is lacking. We therefore studied the expression of tight junction-associated genes in primary rat osteoblasts and bone tissues. Quantitative real-time PCR showed that osteoblasts expressed ZO-1, -2, -3, cingulin, occludin, claudin-1 to -12, -14 to -20, -22 and -23. By using western blot analyses of selected claudins, expression of claudin-5, -11, -14 and -15, but not claudin-3, were identified in osteoblasts. A confocal immunofluorescent study in undecalcified tibial sections confirmed that claudin-16 was localized on the trabecular surface, normally covered by osteoblasts and bone-lining cells. In addition, immunohistochemical studies in decalcified tibial sections demonstrated the expression of claudin-5, -11, -14, -15 and -16 in bone-lining cells (inactive osteoblasts). Primary osteoblasts cultured in the Snapwell for 19-26 days were found to form a monolayer with measurable transepithelial resistance of approximately 110-180 Omegacm(2), confirming the presence of barrier functions of the tight junction. It was concluded that osteoblasts expressed several tight junction-associated proteins, which possibly regulated ion transport across the bone membrane.

Prolactin directly enhances bone turnover by raising osteoblast-expressed receptor activator of nuclear factor kappaB ligand/osteoprotegerin ratio.

Hyperprolactinemia leads to high bone turnover as a result of enhanced bone formation and resorption. Although its osteopenic effect has long been explained as hyperprolactinemia-induced hypogonadism, identified prolactin (PRL) receptors in osteoblasts suggested a possible direct action of PRL on bone. In the present study, we found that hyperprolactinemia induced by anterior pituitary transplantation (AP), with or without ovariectomy (Ovx), had no detectable effect on bone mineral density and content measured by dual-energy X-ray absorptiometry (DXA). However, histomorphometric studies revealed increases in the osteoblast and osteoclast surfaces in the AP rats, but a decrease in the osteoblast surface in the AP+Ovx rats. The resorptive activity was predominant since bone volume and trabecular number were decreased, and the trabecular separation was increased in both groups. Estrogen supplement (E2) fully reversed the effect of estrogen depletion in the Ovx but not in the AP+Ovx rats. In contrast to the typical Ovx rats, bone formation and resorption became uncoupled in the AP+Ovx rats. Therefore, hyperprolactinemia was likely to have some estrogen-independent and/or direct actions on bone turnover. Osteoblast-expressed PRL receptor transcripts and proteins shown in the present study confirmed our hypothesis. Furthermore, we demonstrated that the osteoblast-like cells, MG-63, directly exposed to PRL exhibited lower expression of alkaline phosphatase and osteocalcin mRNA, and a decrease in alkaline phosphatase activity. The ratios of receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) proteins were increased, indicating an increase in the osteoclastic bone resorption. The present data thus demonstrated that hyperprolactinemia could act directly on bone to stimulate bone turnover, with more influence on bone resorption than formation. PRL enhanced bone resorption in part by increasing RANKL and decreasing OPG expressions by osteoblasts.