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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.

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.

Knee joint stability is important for postural stability.Abnormal weight distribution is common in individualswith unilateral osteoarthritis of knee (OA knee) as compensatory mechanism for pain and joint malalignments.Various forms of conventional physiotherapy interventions have been used to prevent further degenerativeprocess. Star excursion balance test (SEBT) has been invented to assess dynamic postural stability. Thispresent study was aimed to investigate effects of SEBT as a postural control exercise training tool(SEBTx)in persons with unilateral OA knee. Fourteen participants were randomly assigned to control group (n = 7)and SEBTx group (n = 7). The control group received weekly routine physiotherapy interventions (jointmobilization, ultrasound therapy, transcutaneous electrical nerve stimulation, and taping). In addition tothe routine interventions, the SEBTxgroup was instructed to perform SEBTxfor 30 min/session, 3 sessions/week, for 4 weeks. Primary outcome (weight distributionon posturography in 8 directions – anterior, Rt.anterolateral, Rt.lateral, Rt. posterolateral, posterior, Lt. posterolateral, Lt. lateral, Lt. anterolateral)wasmeasured at baseline and4 weeks post-intervention. Secondary outcomes numeric pain rating scale (NPRS)and Timed Up and Go test (TUG) were used to assess pain and dynamic balance, respectively. Resultsshowed thatweight distribution inSEBTx group significantly improved in the Lt. posterolateral and posteriordirections post-intervention. Moreover, NPRS in SEBTx group significantly reduced from 47.9±7.4 to33.3±6.0. Lastly, TUG significantly reduced from 13.5±0.9 to 11.5±0.7 s in SEBTx group. In conclusion,the SEBTx should be applied to improve postural balance in individuals with unilateral (OA knee).

Low Back Pain (LBP) is a common disease found in every age that affects daily life. LBP may cause poor posture of the lumbar spine, and decrease muscle performance which leads to muscle fatigue, reduce blood circulation and reduce muscle oxygen saturation. Traditional Thai Massage (TTM) has been used to treat patients with LBP for a long time with some evidence that it could increase muscle flexibility, improve blood circulation and decrease pain. However, its effect on muscle oxygen saturation has not been explored. This study uses one group pretest-posttest design to preliminary determine this effect. Twenty-three subjects (6 males and 17 females) who had non-specific LBP participated. Each of them was measured on muscle oxygen saturation, visual analog scale (VAS) and Sorensen’s test before and immediately after having a 15-minute session of TTM. These measures were compared before and after those of a 15-minute rest period. The results showed significantly increase in muscle oxygen saturation (p < 0.01), increase endurance of back extension (p < 0.05), decrease pain intensity (3.46±2.65) (p < 0.01) and decrease anxiety level (4.04±2.30) (p < 0.01) after received TTM. In conclusion, TTM could improve muscle oxygen saturation level, decrease pain intensity, decrease anxiety level and increase the duration of hold while performing back muscle endurance tests.

Forward head posture (FHP) is a problem with muscle imbalance around neck and shoulder girdle. The FHP might be a silent threat for young adults in their later stages of life. An impact of the FHP on muscle activities in upright posture has been well established; however, how it influences neck and shoulder muscle activities in side lying-position has been still elusive. This study was aimed to investigate electrical muscle activities (% maximum voluntary contraction, %MVC) on both upper and lower sides of 4 neck and shoulder muscles—sternocleidomastoid (SCM), upper trapezius (UT), middle trapezius (MT) and lower trapezius (LT) using surface electromyography (EMG) in 34 participants (normal head posture (NHP) group, aged 21.24±0.97 years old, n=17; and FHP group, aged 20.83±1.20 years old, n=17). Each participant performed side-lying position with a self-selected pillow for 5-min of acclimatization and another 12-min for EMG recordings. Results showed that there was no significant difference between %MVC on upper and lower sides of all muscles in both groups. In contrast, the %MVC of the trapezius muscles on the upper side of the FHP group were significantly higher than the NHP group i.e., 1.26±0.76 vs 0.79±0.44 in UT; and 3.06±1.86 vs 1.74±1.14 in LT, respectively. Despite symmetrical activation of bilateral muscles can be seen in both groups; however, the FHP could induce over activation of UT and LT while resting in side-sleeping position. Therefore, selective technique to minimize muscle activation during resting position might be required as preventive regimen for this group of young adults

Health belief model (HBM) has been widely used to communicate with older persons in order to changetheir behaviors. This group of people have a higher risk of fall due to poor postural balance and inappropriatefall-related behaviors. Home-exercise programs like Otago exercise program (OEP) can ameliorate posturalbalance, but most of the older persons do not well comply with the program. This mixed methods researchstudy was aimed to investigate effects of a 12-week HBM-based OEP (HBM-OEP) on postural balance(Berg balance scale, BBS) and quadriceps torque in 72 healthy community-dwelling older persons (controlgroup, n = 36 and HBM-OEP group, n = 36). Levels of fall-related HBM domains (knowledge, perception,and behaviors) were also recorded at baseline and 12-week post-intervention. Results showed that the BBSincreased from 51.3±0.4 to 53.2±0.3 (p

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.

Contains fulltext : 154292.pdf (Publisher’s version ) (Closed access) 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 (muCT) 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. 01 maart 2015

A fall during walking is a common problem in diabetic patients due to neuromuscular complications of the foot, especially intrinsic foot muscles (IFMs). Short-foot exercise (SFE) has been reported to strengthen IFMs in healthy individuals. This present study was aimed to investigate effects of SFE on medial longitudinal arch integrity (navicular drop test, NDT) and dynamic postural control (star excursion balance test, SEBT). The SEBT values were measured on single-leg standing in 8 directions (anterior, anteromedial, medial, posteromedial, posterior, posterolateral, lateral, and anterolateral) at baseline, week 4, 8, and 12 (follow up) in 15 diabetic patients: control group (n = 7) and SFE group (n = 8). Results showed that NDT was reduced in SFE group compared to control at week 8 and follow up. The normalized SEBT values in SFE group was significantly higher than baseline only in medial direction and increased from baselines in anteromedial, medial, and posteromedial directions at week 4 and 8, respectively. At the follow-up point, only posteromedial direction showed an improvement of normalized SEBT in SFE group. In conclusion, 8-week SFE reduced foot pronation and improved dynamic postural control in a single-leg standing phase of diabetic foot. The SFE should be continuously applied to diabetic foot since the benefits were not well persistent in the follow-up phase.

Item does not contain fulltext 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.

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.

Previous investigations showed that chronic metabolic acidosis (CMA) increased the paracellular permeability of ion and neutral hydrophilic molecules in the duodenum of rats and small intestinal-like cell lines. Since proteins of the claudin family have been known to regulate the paracellular transport in several epithelia, an increase in the paracellular permeability during CMA may have resulted from changes in the pattern of claudin expression. The present study aimed to investigate the expression profile of 22 claudins in the duodenum of female Sprague-Dawley rats given 1.5% NH(4)Cl for 21 days to induce CMA. Arterial blood gas analysis revealed plasma pH values of 7.40 in normal rats and 7.31 in acidotic rats. Blood chemistry showed increases in the total plasma calcium, free-ionized calcium and magnesium, indicating a typical adaptive response of animals to CMA. RT-PCR demonstrated mRNA expressions of claudin-1 to -12, -14, -15, -17 to -20, -22 and -23 in duodenum of normal rats. Claudin-16 was not expressed in normal duodenum, but was strongly expressed in the kidney. Claudin-13 expression was seen only in the cecum, colon, liver and kidney of mice. After 21-day CMA, mRNA expressions of claudin-2, -3, -6, -8, -11, -12, -14, -19 and -22 were significantly enhanced, whereas expressions of other claudins were not changed. Confocal laser-scanning microscopy demonstrated that duodenal enterocytes of normal rats expressed claudin-3 protein on the paracellular membrane. The distribution of claudin-3 protein along the paracellular membrane was markedly increased in CMA, especially near the apical surface. Our results, therefore, provided novel evidence that 21-day CMA markedly altered claudin profile in the duodenum of rats by upregulating specific claudin expression.

Chronic metabolic acidosis results in a negative calcium balance as a result of bone resorption and renal calcium loss. However, reports on the changes in intestinal calcium transport have been controversial. The present investigation therefore aimed to study the effects of chronic metabolic acidosis induced by 1.5% NH4Cl administration on the three components of duodenal calcium transport, namely, solvent drag-induced, transcellular active, and passive paracellular components, in rats using an in vitro Ussing chamber technique. The relative mRNA expression of genes related to duodenal calcium transport was also determined. We found that 21-day chronic metabolic acidosis stimulated solvent drag-induced and transcellular active duodenal calcium transport but not passive paracellular calcium transport. Our results further demonstrated that an acute direct exposure to serosal acidic pH, in contrast, decreased solvent drag-induced calcium transport in a pH-dependent fashion but had no effect on transcellular active calcium transport. Neither the transepithelial resistance nor duodenal permeability to Na+, Cl−, and Ca2+via the passive paracellular pathway were altered by chronic metabolic acidosis, suggesting that widening of the tight junction and changes in the charge-selective property of the tight junction did not occur. Thus the enhanced duodenal calcium transport observed in chronic metabolic acidosis could have resulted from a long-term adaptation, possibly at the molecular level. RT-PCR study revealed that chronic metabolic acidosis significantly increased the relative mRNA expression of duodenal genes associated with solvent drag-induced transport, i.e., the β1-subunit of Na+-K+-ATPase, zonula occludens-1, occludin, and claudin-3, and with transcellular active transport, i.e., transient receptor potential vanilloid family Ca2+channels 5 and 6 and plasma membrane Ca2+-ATPase isoform 1b. Total plasma calcium and free ionized calcium and magnesium concentrations were also increased, whereas serum parathyroid hormone and 1α,25-dihydroxyvitamin D3levels were not changed. The results indicated that 21-day chronic metabolic acidosis affected the calcium metabolism in rats partly through enhancing the mRNA expression of crucial duodenal genes involved in calcium absorption, thereby stimulating solvent drag-induced and transcellular active calcium transport in the duodenum.

Prolactin, having been shown to stimulate transcellular active and solvent drag-induced calcium transport in the duodenum of female rats, was postulated to improve duodenal calcium transport in estrogen-deficient rats. The aim of the present study was, therefore, to demonstrate the effects of long-term prolactin exposure produced by anterior pituitary (AP) transplantation on the duodenal calcium transport in young (9-week-old) and adult (22-week-old) ovariectomized rats. We found that ovariectomy did not alter the transcellular active duodenal calcium transport in young and adult rats fed normal calcium diet (1.0% w/w Ca) but decreased the solvent drag-induced duodenal calcium transport from 75.50 ± 10.12 to 55.75 ± 4.77 nmol·hr–1 cm–2 (P < 0.05) only in adult rats. Long-term prolactin exposure stimulated the transcellular active calcium transport in young and adult AP-grafted ovariectomized rats fed with normal calcium diet by more than 2-fold from 7.56 ± 0.79 to 16.54 ± 2.05 (P < 0.001) and 9.78 ± 0.72 to 15.99 ± 1.75 (P < 0.001) nmol·hr–1 cm–2, respectively. However, only the solvent drag-induced duodenal calcium transport in young rats was enhanced by prolactin from 95.51 ± 10.64 to 163.20 ± 18.03 nmol·hr–1 cm–2 (P < 0.001) whereas that in adult rats still showed a decreased flux from 75.50 ± 10.12 to 47.77 ± 5.42 nmol·hr–1 cm–2 (P < 0.05). Because oral calcium supplement has been widely used to improve calcium balance in estrogen-deficient animals, the effect of a high-calcium diet (2.0% w/w Ca) was also investigated. The results showed that stimulatory action of long-term prolactin on the transcellular active duodenal calcium transport in both young and adult rats was diminished after being fed a high-calcium diet. The same diet also abolished prolactin-enhanced solvent drag-induced duodenal calcium transport in young and further decreased that in adult AP-grafted ovariectomized rats. We concluded that the solvent drag-induced duodenal calcium transport in adult rats was decreased after ovariectomy. Long-term prolactin exposure stimulated the transcellular active duodenal calcium transport in both young and adult rats whereas enhancing the solvent drag-induced duodenal calcium transport only in young rats. Effects of prolactin were abolished by a high-calcium diet.

Contains fulltext : 109998.pdf (Publisher’s version ) (Closed access) 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. 01 maart 2012

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·cm2. The monolayers also established opposing transcellular concentration gradients of Na+ and K+. Radioactive 22Na+ 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 22Na+ transport significantly by four times, which could be totally blocked by 100 μM hydrochlorothiazide. Angiotensin II-stimulated 22Na+ 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.

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.

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.

High physiological prolactin induced positive calcium balance by stimulating intestinal calcium absorption, reducing renal calcium excretion, and increasing bone calcium deposition in female rats. Although prolactin-induced increase in trabecular bone calcium deposition was absent after ovariectomy, its effects on cortical bones were still controversial. The present investigation, therefore, aimed to study the effect of in vivo long-term high physiological prolactin induced by either anterior pituitary (AP) transplantation or 2.5 mg/kg prolactin injection on cortical bones in ovariectomized rats. Since the presence of prolactin receptors (PRLR) in different bones of normal adult rats has not been reported, we first determined mRNA expression of both short- and long-form PRLRs at the cortical sites (tibia and femur) and trabecular sites (calvaria and vertebrae) by using the RT-PCR. Our results showed the mRNA expression of both PRLR isoforms with predominant long form at all sites. However, high prolactin levels induced by AP transplantation in normal rats did not have any effect on the femoral bone mineral density or bone mineral content. By using45Ca kinetic study, 2.5 mg/kg prolactin did not alter bone formation, bone resorption, calcium deposition, and total calcium content in tibia and femur of adult ovariectomized rats. AP transplantation also had no effect on the cortical total calcium content in adult ovariectomized rats. Because previous work showed that the effects of prolactin were age dependent and could be modulated by high-calcium diet, interactions between prolactin and these two parameters were investigated. The results demonstrated that 2.0% wt/wt high-calcium diet significantly increased the tibial total calcium content in 9-wk-old young AP-grafted ovariectomized rats but decreased the tibial total calcium content in 22-wk-old adult rats. As for the vertebrae, the total calcium contents in both young and adult rats were not changed by high-calcium diet. The present results thus indicated that the adult cortical bones were potentially direct targets of prolactin. Moreover, the effects of high physiological prolactin on cortical bones were age dependent and were observed only under the modulation of high-calcium diet condition.