Repercussões metabólicas e uso dos medicamentos sensibilizadores da insulina em mulheres com síndrome dos ovários policísticos / Metabolic repercussions and use of insulin-sensitizing drugs in women with polycystic ovary syndrome

A síndrome dos ovários policísticos (SOP) é um distúrbio endócrino-metabólico muito frequente no período reprodutivo. Quando associado ao distúrbio metabólico, as mulheres com SOP podem ter ainda risco acrescido para doença cardiovascular. O objetivo deste manuscrito é descrever as repercussões metabólicas, incluindo quais as principais, como investigar e as consequências desse distúrbio sobre a saúde da mulher. É uma revisão narrativa mostrando a implicação da resistência insulínica, das dislipidemias e da síndrome metabólica sobre o sistema reprodutor e sobre o risco cardiovascular da mulher com SOP, bem como do uso de sensibilizadores de insulina no seu tratamento. Conclui-se que a correção dos distúrbios metabólicos na SOP é benéfica tanto para o sistema reprodutor quanto para o cardiovascular. A primeira linha de tratamento é a mudança de estilo de vida e a perda de peso. Na resposta inadequada, o tratamento medicamentoso está recomendado. Nas mulheres com obesidade mórbida que não tiveram bons resultados com o tratamento clínico, a cirurgia bariátrica é uma opção.(AU)

Hydrogen peroxide inhibits Ca²⁺ efflux through plasma membrane Ca²⁺-ATPase in mouse parotid acinar cells

Intracellular Ca²⁺ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide (H₂O₂) on cytosolic Ca²⁺ accumulation in mouse parotid acinar cells. Intracellular Ca²⁺ levels were slowly elevated when 1 mM H₂O₂ was perfused in the presence of normal extracellular Ca²⁺. In a Ca²⁺-free medium, 1 mM H₂O₂ still enhanced the intracellular Ca²⁺ level. Ca²⁺ entry tested using manganese quenching technique was not affected by perfusion of 1 mM H₂O₂. On the other hand, 10 mM H₂O₂ induced more rapid Ca²⁺ accumulation and facilitated Ca²⁺ entry from extracellular fluid. Ca²⁺ refill into intracellular Ca²⁺ store and inositol 1,4,5-trisphosphate (1 µM)-induced Ca²⁺ release from Ca²⁺ store was not affected by 1 mM H₂O₂ in permeabilized cells. Ca²⁺ efflux through plasma membrane Ca²⁺-ATPase (PMCA) was markedly blocked by 1 mM H₂O₂ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected H₂O₂-induced Ca²⁺ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of H₂O₂ under pathological conditions may lead to cytosolic Ca²⁺ accumulation and that the primary mechanism of H₂O₂-induced Ca²⁺ accumulation is likely to inhibit Ca²⁺ efflux through PMCA rather than mobilize Ca²⁺ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

Flow Shear Stress Enhances the Proliferative Potential of Cultured Radial Glial Cells Possibly Via an Activation of Mechanosensitive Calcium Channel

Radial glial cells (RGCs) which function as neural stem cells are known to be non-excitable and their proliferation depends on the intracellular calcium (Ca²⁺) level. It has been well established that Inositol 1,4,5-trisphosphate (IP3)-mediated Ca²⁺ release and Ca²⁺ entry through various Ca²⁺ channels are involved in the proliferation of RGCs. Furthermore, RGCs line the ventricular wall and are exposed to a shear stress due to a physical contact with the cerebrospinal fluid (CSF). However, little is known about how the Ca²⁺ entry through mechanosensitive ion channels affects the proliferation of RGCs. Hence, we hypothesized that shear stress due to a flow of CSF boosts the proliferative potential of RGCs possibly via an activation of mechanosensitive Ca²⁺ channel during the embryonic brain development. Here, we developed a new microfluidic two-dimensional culture system to establish a link between the flow shear stress and the proliferative activity of cultured RGCs. Using this microfluidic device, we successfully visualized the artificial CSF and RGCs in direct contact and found a significant enhancement of proliferative capacity of RGCs in response to increased shear stress. To determine if there are any mechanosensitive ion channels involved, a mechanical stimulation by poking was given to individual RGCs. We found that a poking on radial glial cell induced an increase in intracellular Ca²⁺ level, which disappeared under the extracellular Ca²⁺-free condition. Our results suggest that the shear stress by CSF flow possibly activates mechanosensitive Ca²⁺ channels, which gives rise to a Ca²⁺ entry which enhances the proliferative capacity of RGCs.

Gintonin, an exogenous ginseng-derived LPA receptor ligand, promotes corneal wound healing

Ginseng gintonin is an exogenous ligand of lysophosphatidic acid (LPA) receptors. Accumulating evidence shows LPA helps in rapid recovery of corneal damage. The aim of this study was to evaluate the therapeutic efficacy of gintonin in a rabbit model of corneal damage. We investigated the signal transduction pathway of gintonin in human corneal epithelium (HCE) cells to elucidate the underlying molecular mechanism. We next evaluated the therapeutic effects of gintonin, using a rabbit model of corneal damage, by undertaking histochemical analysis. Treatment of gintonin to HCE cells induced transient increases of [Ca²⁺](i) in concentration-dependent and reversible manners. Gintonin-mediated mobilization of [Ca²⁺](i) was attenuated by LPA1/3 receptor antagonist Ki16425, phospholipase C inhibitor U73122, inositol 1,4,5-triphosphate receptor antagonist 2-APB, and intracellular Ca²⁺ chelator BAPTA-AM. Gintonin facilitated in vitro wound healing in a concentration-dependent manner. When applied as an eye-drop to rabbits with corneal damage, gintonin rapidly promoted recovery. Histochemical analysis showed gintonin decreased corneal apoptosis and increased corneal cell proliferation. We demonstrated that LPA receptor activation by gintonin is linked to in vitro and in vivo therapeutic effects against corneal damage. Gintonin can be applied as a clinical agent for the rapid healing of corneal damage.

Effect of Chaiqin Chengqi Decoction on cholecystokinin receptor 1-mediated signal transduction of pancreatic acinar cells in acute necrotizing pancreatitis rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of Chaiqin Chengqi Decoction (,CQCQD) on cholecystokinin receptor 1 (CCKR1)-mediated signal transduction of pancreatic acinar cell in rats with acute necrotic pancreatitis (ANP).</p><p><b>METHODS</b>Twenty-seven Sprague-Dawley rats were randomized into three groups: the control group, the ANP group, and the CQCQD group (9 in each group). ANP rats were induced by two intraperitoneal injections of 8% L-arginine (pH=7.0, 4.4 g/kg) over a 2-h period. Rats were treated with 1.5 mL/100 g body weight of CQCQD (CQCQD group) or physiological saline (control and ANP groups) at 2 h interval. And 6 h after induction, pancreatic tissues were collected for histopathological examination. Pancreatic acinar cells were isolated for determination of CCKR1 mRNA and protein expression, phospholipase C (PLC) and inositol-1,4,5-triphosphate (IP3), and determination of fluorescence intensity (FI) as a measure of intracellular calcium ion concentration [Ca(2+)]i.</p><p><b>RESULTS</b>The pancreatic histopathological score (6.2 ± 1.1) and the levels of PLC (1,187.2 ± 228.2 μg/mL) and IP3 (872.2 ± 88.4 μg/mL) of acinar cells in the ANP group were higher than those in the control (2.8 ± 0.4, 682.5 ± 121.8 μg/mL, 518.4 ± 115.8 μg/mL) and the CQCQD (3.8 ± 0.8, 905.3 ± 78.5 μg/mL, 611.0 ± 42.5 μg/mL) groups (P<0.05). [Ca(2+)]i FI for the ANP group (34.8±27.0) was higher than that in the control (5.1 ± 2.2) and CQCQD (12.6 ± 2.5) groups (P<0.05). The expression of pancreatic acinar cell CCKR1 mRNA in the ANP group was up-regulated (expression ratio=1.761; P=0.024) compared with the control group. The expression of pancreatic acinar cell CCKR1 mRNA in the CQCQD group was down-regulated (expression ratio=0.311; P=0.035) compared with the ANP group. The ratio of gray values of the CCKR1 and β-actin in the ANP group (1.43 ± 0.17) was higher than those in the control (0.70 ± 0.15) and CQCQD (0.79 ± 0.11) groups (P<0.05).</p><p><b>CONCLUSIONS</b>Pancreatic acinar cell calcium overload of ANP induced by L-arginine was related to the up-regulated expressions of pancreatic acinar cell CCKR1 mRNA and protein. CQCQD can down-regulate expressions of pancreatic acinar cell CCKR1 mRNA and protein to reduce the PLC and IP3 of pancreatic acinar cells, relieving the calcium overload and reducing the pathological changes in rats with ANP.</p>

House Dust Mite Extract Induces PLC/IP3-dependent Ca2+ Signaling and IL-8 Expression in Human Gingival Epithelial Cells

The gingival epithelium of the oral cavity is constantly exposed to exogenous stimuli such as bacterial toxins, allergens, and thermal changes. These exogenous stimuli are resisted by innate host defense in gingival epithelial cells. However, it is unclear exactly how the exogenous stimuli affect detrimentally on the human gingival epithelial cells. Here, we investigated whether the allergen, such as house dust mite (HDM) extract, is linked to Ca2+ signaling and proinflammatory cytokine expression in primary cultured human gingival epithelial cells. HDM extract induced an increase in intracellular Ca2+ concentration ([Ca2+]i) in a dose-dependent manner. Extracellular Ca2+ depletion did not affected on the HDM extract-induced increase in [Ca2+]i. The HDM extract-induced increase in [Ca2+]i was abolished by the treatment with U73122 and 2-APB, which are inhibitors of phospholipase C (PLC) and inositol 1,4,5-trisphosphate (IP3) receptor. Moreover, HDM extract induced the mRNA expression of pro-inflammatory cytokine, interleukin (IL)-8. These results suggest that HDM extract triggers PLC/IP3-dependent Ca2+ signaling and IL-8 mRNA expression in primary cultured human gingival epithelial cells.

Mercury Promotes Catecholamines Which Potentiate Mercurial Autoimmunity and Vasodilation: Implications for Inositol 1,4,5-Triphosphate 3-Kinase C Susceptibility in Kawasaki Syndrome

Previously, we reviewed biological evidence that mercury could induce autoimmunity and coronary arterial wall relaxation as observed in Kawasaki syndrome (KS) through its effects on calcium signaling, and that inositol 1,4,5-triphosphate 3-kinase C (ITPKC) susceptibility in KS would predispose patients to mercury by increasing Ca2+ release. Hg2+ sensitizes inositol 1,4,5-triphosphate (IP3) receptors at low doses, which release Ca2+ from intracellular stores in the sarcoplasmic reticulum, resulting in delayed, repetitive calcium influx. ITPKC prevents IP3 from triggering IP3 receptors to release calcium by converting IP3 to inositol 1,3,4,5-tetrakisphosphate. Defective IP3 phosphorylation resulting from reduced genetic expressions of ITPKC in KS would promote IP3, which increases Ca2+ release. Hg2+ increases catecholamine levels through the inhibition of S-adenosylmethionine and subsequently catechol-O-methyltransferase (COMT), while a single nucleotide polymorphism of the COMT gene (rs769224) was recently found to be significantly associated with the development of coronary artery lesions in KS. Accumulation of norepinephrine or epinephrine would potentiate Hg2+-induced calcium influx by increasing IP3 production and increasing the permeability of cardiac sarcolemma to Ca2+. Norepinephrine and epinephrine also promote the secretion of atrial natriuretic peptide, a potent vasodilator that suppresses the release of vasoconstrictors. Elevated catecholamine levels can induce hypertension and tachycardia, while increased arterial pressure and a rapid heart rate would promote arterial vasodilation and subsequent fatal thromboses, particularly in tandem. Genetic risk factors may explain why only a susceptible subset of children develops KS although mercury exposure from methylmercury in fish or thimerosal in pediatric vaccines is nearly ubiquitous. During the infantile acrodynia epidemic, only 1 in 500 children developed acrodynia whereas mercury exposure was very common due to the use of teething powders. This hypothesis mirrors the leading theory for KS in which a widespread infection only induces KS in susceptible children. Acrodynia can mimic the clinical picture of KS, leading to its inclusion in the differential diagnosis for KS. Catecholamine levels are often elevated in acrodynia and may also play a role in KS. We conclude that KS may be the acute febrile form of acrodynia.

Dexmedetomidine-induced contraction of isolated rat aorta is dependent on extracellular calcium concentration / 대한마취과학회지

BACKGROUND: Dexmedetomidine is a highly selective alpha2-adrenoceptor agonist that is widely used for sedation and analgesia during the perioperative period. Intravenous administration of dexmedetomidine induces transient hypertension due to vasoconstriction via the activation of the alpha2-adrenoceptor on vascular smooth muscle. The goal of this in vitro study is to investigate the calcium-dependent mechanism underlying dexmedetomidine-induced contraction of isolated endothelium-denuded rat aorta. METHODS: Isolated endothelium-denuded rat thoracic aortic rings were suspended for isometric tension recording. Cumulative dexmedetomidine concentration-response curves were generated in the presence or absence of the following inhibitors: alpha2-adrenoceptor inhibitor rauwolscine; voltage-operated calcium channel blocker verapamil (5 x 10(-7), 10(-6) and 5 x 10(-5) M); purported inositol 1,4,5-trisphosphate receptor blocker 2-aminoethoxydiphenylborate (5 x 10(-6), 10(-5) and 5 x 10(-5) M); phospholipase C inhibitor U-73122 (10(-6) and 3 x 10(-6) M); and store-operated calcium channel inhibitor gadolinium chloride hexahydrate (Gd3+; 5 x 10(-6) M). Dexmedetomidine concentration-response curves were also generated in low calcium concentrations (1 mM) and calcium-free Krebs solution. RESULTS: Rauwolscine, verapamil, and 2-aminoethoxydiphenylborate attenuated dexmedetomidine-induced contraction in a concentration-dependent manner. Low calcium concentrations attenuated dexmedetomidine-induced contraction, and calcium-free Krebs solution nearly abolished dexmedetomidine-induced contraction. However, U-73122 and Gd3+ had no effect on dexmedetomidine-induced contraction. CONCLUSIONS: Taken together, these results suggest that dexmedetomidine-induced contraction is primarily dependent on extracellular calcium concentrations that contribute to calcium influx via voltage-operated calcium channels of isolated rat aortic smooth muscle. Dexmedetomidine-induced contraction is mediated by alpha2-adrenoceptor stimulation. Dexmedetomidine-induced contraction appears to be partially mediated by calcium release from the sarcoplasmic reticulum.

Effects of Inositol 1,4,5-triphosphate on Osteoclast Differentiation in RANKL-induced Osteoclastogenesis

The receptor activator of NF-kappaB ligand (RANKL) signal is an activator of tumor necrosis factor receptor-associated factor 6 (TRAF6), which leads to the activation of NF-kappaB and other signal transduction pathways essential for osteoclastogenesis, such as Ca2+ signaling. However, the intracellular levels of inositol 1,4,5-trisphosphate (IP3) and IP3-mediated cellular function of RANKL during osteoclastogenesis are not known. In the present study, we determined the levels of IP3 and evaluated IP3-mediated osteoclast differentiation and osteoclast activity by RANKL treatment of mouse leukemic macrophage cells (RAW 264.7) and mouse bone marrow-derived monocyte/macrophage precursor cells (BMMs). During osteoclastogenesis, the expression levels of Ca2+ signaling proteins such as IP3 receptors (IP3Rs), plasma membrane Ca2+ ATPase, and sarco/endoplasmic reticulum Ca2+ ATPase type2 did not change by RANKL treatment for up to 6 days in both cell types. At 24 h after RANKL treatment, a higher steady-state level of IP3 was observed in RAW264.7 cells transfected with green fluorescent protein (GFP)-tagged pleckstrin homology (PH) domains of phospholipase C (PLC) delta, a probe specifically detecting intracellular IP3 levels. In BMMs, the inhibition of PLC with U73122 [a specific inhibitor of phospholipase C (PLC)] and of IP3Rs with 2-aminoethoxydiphenyl borate (2APB; a non-specific inhibitor of IP3Rs) inhibited the generation of RANKL-induced multinucleated cells and decreased the bone-resorption rate in dentin slice, respectively. These results suggest that intracellular IP3 levels and the IP3-mediated signaling pathway play an important role in RANKL-induced osteoclastogenesis.

Effects of instant electroacupuncture at the different acupoints on IP3 in the uterus tissue of dysmenorrhea model rats / 中国针灸

<p><b>OBJECTIVE</b>To compare the effects of instant electroacupuncture (EA) at the different acupoints on IP3 in the uterus tissue of dysmenorrhea model rats so as to investigate the specificity of acupoints.</p><p><b>METHODS</b>Fifty female SD rats were randomly divided into a saline group, a model group, a Sanyinjiao (SF 6) group, a Xuehai (SP 10) group and a Hegu (LI 4) group, 10 rats in each group. The rats were given subcutaneous injection of Estradiol Beozoate injection for 10 consecutive days except those in the saline group, and intraperitoneal injection of 2U Oxytocin at 1 h after the last administration to create the dysmenorrhea rats model, and the saline group was given the same dose of saline every day. On the 10th day the rats in each EA group were given EA 20 min, and the rats in the saline group and model group were bound 20 min, and the writhing response was observed at the same time. The uterine IP3 contents were detected with enzyme-linked immunosorbent assay method.</p><p><b>RESULTS</b>(1) Compared with (0.311+/- 0.253) in the saline group, the writhing scores per minute of (5.867 +/- 3.442) in the model group and (2.311 +/- 0.957) in the Xuehai (SP 10) group were both increased significantly (P < 0.01, P < 0.05), and (1.833 +/- 1.355) in the Sanyinjiao (SP 6) group and (0.743 +/- 0.306) in the Hegu (LI 4) group showed no significant differences (P > 0.05). Compared with that in the model group, the writhing scores per minute decreased significantly (all P < 0.01) in all the EA groups, with no significant differences among all the EA groups (all P > 0.05). (2) Compared with (2.698 +/- 1.491) ng/mg in the saline group, IP3 contents of the uterus of (0.813 +/- 0.899) ng/mg in the model group, (1.740 +/- 0.375) ng/mg in the Sanyinjiao (SP 6) group and (0.692 +/- 0.212) ng/mg in the Hegu (LI 4) group were all lower significantly (P < 0.05, P < 0.01), and (0.743+/- 0.306) ng/mg in the Xuehai (SP 10) group showed no significant differences (P > 0.05). Compared with that in the model group, IP3 content of the uterus in the Hegu (LI 4) group showed no significant difference (P > 0.05), and those in the Sanyinjiao (SP 6) group and in the Xuehai (SP 10) group increased significantly (both P < 0 05), which were significantly higher than that in the Hegu (II 4) group (P < 0.05, P < 0.01).</p><p><b>CONCLUSION</b>There are no significant differences among the instant EA groups in improving the dysmenorrhea symptoms, but there is obvious specificity of acupoint effects in the regulation of IP3. Electroacupuncture at "Sanyinjiao (SP 6) " Xuehai (SP 10)" has more marked effect in dysmenorrhea model rats.</p>

ERp44 C160S/C212S mutants regulate IP3R1 channel activity

Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release (IICR) via IP(3)R(1), but the mechanism remains largely unexplored. Using extracellular ATP to induce intracellular calcium transient as an IICR model, Ca(2+) image, pull down assay, and Western blotting experiments were carried out in the present study. We found that extracellular ATP induced calcium transient via IP(3)Rs (IICR) and the IICR were markedly decreased in ERp44 overexpressed Hela cells. The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331-377) mutants of ERp44 on IICR were significantly decreased compared with ERp44. However, the binding capacity of ERp44 to L3V domain of IP(3)R(1) (1L3V) was enhanced by ERp44 C160S/C212S mutation. Taken together, these results suggest that the mutants of ERp44, C160/C212, can more tightly bind to IP(3)R(1) but exhibit a weak inhibition of IP(3)R(1) channel activity in Hela cells.

UTP regulates spontaneous transient outward currents in porcine coronary artery smooth muscle cells through PLC-IP(3) signaling pathway / 生理学报

The aim of the present study was to investigate the effects of inositol 1,4,5-trisphosphate (IP(3))-generating agonist UTP on spontaneous transient outward currents (STOCs), and explore the role of intracellular Ca(2+) release in the current response mediated by IP(3) in porcine coronary artery smooth muscle cells (CASMCs). The coronary artery was excised from the fresh porcine heart and cut into small segments (2 mm × 5 mm) and then transferred to enzymatic dissociation solution for incubation. Single CASMCs were obtained by two-step enzyme digestion at 37 °C. STOCs were recorded and characterized using the perforated whole-cell patch-clamp configuration in freshly isolated porcine CASMCs. The currents were amplified and filtered by patch-clamp amplifier (Axopatch 200B), and then the digitized data were recorded by pClamp 9.0 software and further analyzed by MiniAnalysis 6.0 program. The results were as follows: (1) UTP led to conspicuous increases in STOC amplitude by (57.54±5.34)% and in frequency by (77.46±8.42)% (P<0.01, n=38). (2) The specific blocker of phospholipase C (PLC) - U73122 (5 μmol/L) remarkably reduced STOC amplitude by (31.04±7.46)% and frequency by (41.65±16.59)%, respectively (P<0.05, n=10). In the presence of U73122, UTP failed to reactivate STOCs (n=7). (3) Verapamil (20 μmol/L) and CdCl2 (200 μmol/L), two blockers of L-type voltage-dependent Ca(2+) channels, had little effects on STOCs initiated by UTP (n=8). (4) 1 μmol/L bisindolylmaleimide I (BisI), a potent blocker of protein kinase C (PKC), significantly increased STOC amplitude by (65.44±24.66)% and frequency by (61.35±21.47)% (P<0.01, n=12); UTP (40 μmol/L), applied in the presence of 1 μmol/L BisI, could further increase STOC activity (P<0.05, P<0.01, n=12). Subsequent application of ryanodine (50 μmol/L) abolished STOC activity. (5) In the presence of UTP (40 μmol/L), inhibition of IP(3) receptors (IP(3)Rs) by 2-aminoethoxydiphenyl borate (2-APB, 40 μmol/L) reduced STOC amplitude by (24.08±3.97)% (P<0.05, n=8), but had little effect on STOC frequency (n=8). While application of 2-APB (80 μmol/L) significantly reduced STOC amplitude by (31.43±6.34)% and frequency by (40.59±19.01)%, respectively (P<0.05, P<0.01, n=6). Subsequent application of ryanodine (50 μmol/L) completely blocked STOC activity. Pretreatment of cells with 2-APB (40 μmol/L) or ryanodine (50 μmol/L), UTP (40 μmol/L) failed to reactivate STOCs. The results suggest that UTP activates STOCs mainly via PLC and IP(3)-dependent mechanisms. Complex Ca(2+)-mobilization pathways are involved in UTP-mediated STOC activation in porcine CASMCs.

The extracellular calcium sensing receptor is expressed in mouse mesangial cells and modulates cell proliferation

The extracellular calcium sensing receptor (CaSR) belongs to the type III family of G-protein-coupled receptors, a family that comprises the metabotropic glutamate receptor and the putative vomeronasal organ receptors. The CaSR plays an important role for calcium homeostasis in parathyroid cells, kidney cells and other cells to directly 'sense' changes in the extracellular calcium ion concentration ((Ca2+)o). The mesangial cells are known to be involved in many pathologic sequences through the mediation of altered glomerular hemodynamics, cell proliferation, and matrix production. In this study, we examined the expression of the CaSR in the mouse mesangial cell lines (MMC, ATCC number CRL-1927). Reverse transcription- polymerase chain reaction (RT-PCR) was perform with CaSR-specific primers, and this was followed by nucleotide sequencing of the amplified product; this process identified the CaSR transcript in the MMCs. Moreover, CaSR protein was present in the MMCs as assessed by Western blot and immunocytochemical analysis using a polyclonal antibody specific for the CaSR. Functionally, (Ca2+)o induced the increment of the intracellular calcium concentration ((Ca2+)i) in a dose-dependent manner. This (Ca2+)i increment by (Ca2+)o was attenuated by the pretreatment with a phospholipase C inhibitor (U73122) and also by a pretreatment with a CaSR antagonist (NPS 2390). The similar results were also obtained in IP3 accumulation by (Ca2+)o. To investigate the physiological effect of the CaSR, the effect of the (Ca2+)o on cell proliferation was studied. The increased (Ca2+)o (up to 10 mM) produced a significant increase in the cell numbers. This mitogenic effect of (Ca2+)o was inhibited by the co-treatment with a CaSR antagonist. From these results, the (Ca2+)o-induced (Ca2+)i elevation in the MMC is coupled with the extracellular calcium sensing receptor. Furthermore, (Ca2+)o produces a mitogenic effect in MMCs.

Inositol 5'-phosphatase, SHIP1 interacts with phospholipase C-gamma1 and modulates EGF-induced PLC activity

Phospholipase C-gamma1, containing two SH2 and one SH3 domains which participate in the interaction between signaling molecules, plays a significant role in the growth factor-induced signal transduction. However, the role of the SH domains in the growth factor-induced PLC-gamma1 regulation is unclear. By peptide-mass fingerprinting analysis, we have identified SHIP1 as the binding protein for the SH3 domain of PLC-gamma1. SHIP1 was co-immunoprecipitated with PLC-gamma1 and potentiated EGF-induced PLC-gamma1 activation. However, inositol 5'-phosphatase activity of SHIP1 was not required for the potentiation of EGF-induced PLC-gamma1 activation. Taken together, these results suggest that SHIP1 may function as an adaptor protein which can potentiate EGF-induced PLC-gamma1 activation without regards to its inositol 5'-phosphatase activity.

Effect of prostaglandin E2 and the tumor necrosis factor-alpha on second messenger of lung fibroblast / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To Study the effect of prostaglandin E(2) (PGE(2)) combined with tumor necrosis factor-alpha (TNF-alpha) on the second messenger of mouse lung fibroblast in order to research new target point for cytokine to treatment of pneumoconiosis.</p><p><b>METHODS</b>The lung fibroblasts of breed mouse were primarily cultured. 10 ng/ml TNF-alpha and 10 ng/ml TNF-alpha combined with PGE(2) of different doses were added to culture medium of fibroblasts. The gamma value and CPM value were respectively measured for second messenger of cAMP, cGMP and IP(3) of fibroblast by immune-radio assay at different observation time.</p><p><b>RESULTS</b>When treated with 10 ng/ml TNF-alpha + 1,000 pg/ml PGE(2) at 120 s time points, the CPM value of IP(3) of fibroblast was the maximal value [(76.33 +/- 7.10) CPM]; when cAMP/cGMP ratio declined to 4.29 at 24 h time point, the effect of fibroblast proliferation was the strongest; when 10 ng/ml TNF-alpha + 500 pg/ml PGE(2), and 2 000 pg/ml PGE(2), the CPM value of IP(3) of fibroblast were 27.00 +/- 3.00 and 61.00 +/- 2.65 respectively at 120 s time point, cAMP/cGMP value were 3.50 and 9.83 respectively at 24 h, the effect on fibroblast proliferation were obviously lower.</p><p><b>CONCLUSION</b>Certain dose of PGE(2) could raise the ratio of cAMP/cGMP of fibroblast, and antagonize the proliferation effect of TNF-alpha on fibroblast.</p>

Effect of IP3 on BK channels of porcine coronary artery smooth muscle cells / 生理学报

D-myo-inositol 1,4,5-trisphosphate (IP(3)) plays an important role in signal transduction. It releases Ca(2+) from intracellular sites, which activates the Ca(2+)-dependent channels such as large-conductance Ca(2+)-activated potassium channels (BK channels). The present study was therefore designed to determine if the activity of BK channels in porcine coronary artery smooth muscle cells was increased by IP(3). Using the inside-out patch-clamp technique, the activity of single BK channels was recorded in porcine coronary artery smooth muscle cells. In excised inside-out membrane patches, IP(3) (10-50 micromol/L) enhanced the open probability (Po) of BK channels in a dose-dependent manner in the intracellular side of inside-out patches and its effect was almost completely abolished by washout. The open-state probability of the BK channels increased from a control level of 0.0402+/-0.0152 to 0.1365+/-0.0212 (20 micromol/L IP(3)) and 0.1865+/-0.0175 (30 micromol/L IP(3)). IP(3) decreased the mean close time markedly, but had no effect on the amplitude of BK channels. The activation of IP(3) on BK channels did not decline. The metabolite of IP(3) had no obvious effect on BK channels. This study provides evidence that IP(3) activates BK channels in porcine coronary artery smooth muscle cells in a dose-dependence manner.

Adrenomedullin reduces intracellular calcium concentration in cultured hippocampal neurons / 生理学报

The effects of adrenomedullin (ADM) on intracellular calcium concentration ([Ca(2+)](i)) were investigated in cultured hippocampal neurons. Changes in [Ca(2+)](i) were detected by laser scanning confocal microscopy using Fluo 3-AM as the calcium fluorescent probe. [Ca(2+)](i) was represented by relative fluorescent intensity. The results showed that: (1) ADM (0.01-1.0 micromol/L) decreased the resting [Ca(2+)](i) in a concentration-dependent manner. (2) Calcitonin gene-related peptide receptor antagonist CGRP(8-37) significantly inhibited the effects of ADM. (3) ADM significantly reduced the increase in [Ca(2+)](i) induced by high K(+). (4) ADM markedly inhibited the inositol 1,4,5-trisphosphate (IP(3))-induced increase in [Ca(2+)](i), while did not influence ryanodine-evoked increase in [Ca(2+)](i). These results suggest that ADM reduces [Ca(2+)](i) in cultured hippocampal neurons through suppressing Ca(2+) release from IP(3)-sensitive stores. Although ADM does not alter resting Ca(2+) influx, it significantly suppresses Ca(2+) influx activated by high K(+). These effects may be partly mediated by CGRP receptors. ADM in the CNS may act as a cytoprotective factor in ischemic/hypoxic conditions.

assay for phosphoinositide-specific phospholipase C and the effect of pyridoxal-5-phosphate on the assay

In platelets, the major stimulatory second messengers are inositol 1, 4, 5 triphosphate [IP3] and 1,2-diacyiglycerol [DAG] produced upon the hydrolysis of phosphoinositides by phosphoinositide-speciftc phospholpase C [P1-PLC]. Pyridoxal-5-phosphate [PLP] is well known as a potent inhibitor of platelet aggregation. The mechanism[s] of its inhibitory action remains to be elucidated. P1-PLC was assayed and the effect of PLP on the assay was examined in an attempt to explain the nature of the inhibitory effect of PLP on platelet function. The assay was satisfactory and was inhibited by PLP with full inhibition at 10mMPLP

Cell biological mechanism involved in the effect of sodium selenite on improving insulin sensitivity / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the cell biological mechanism of sodium selenite improving insulin sensitivity in pubertal rats with insulin resistance.</p><p><b>METHODS</b>The content of inositol 1,4,5-trisphosphate (IP3) was examined by anion resin chromatography, and mRNA levels of phosphatidylinositol 3-kinase regulatory subunits (PI3Kp85 alpha) and Se-P were detected by RT-PCR in hepatocyte isolated from pubertal rats with insulin resistance.</p><p><b>RESULTS</b>The mRNA levels of Se-P and PI3Kp85 alpha and content of IP3 in isolated hepatocyte decreased in pubertal male rats with insulin resistance. The above indices increased and reached normal level in rats supplied with selenium. The response to insulin stimulation in isolated hepatocyte in rats with selenium supply was similar to that in the control group, and both groups had higher response than those with high-fat diet. Alone when inhibited by wortmannin, the concentration of IP3 increased slightly in rats with selenium supply, but still was lower than that in the control group.</p><p><b>CONCLUSIONS</b>These results indicate that the effect of selenium improving insulin sensitivity may be related to phosphatidylinositol PI3K signalling pathway. The effect of regulation of IP3 by selenium is not as effective as that by insulin, which may explain the difference of effect between selenium and insulin.</p>

The effect of Ni2+ on the intracellular Ca2+ increase of the mouse early 2-cell embryos / 대한불임학회지

OBJECTIVE: We reported the overcoming effect of Ni2+ on the in vitro 2-cell block of mouse embryos. In this study, we aim to investigate whether Ni2+ should induce intracellular Ca2+ transient in the mouse embryos. MATERIALS AND METHODS: Embryos were collected at post hCG 32hr from the oviduct of the ICR mouse and cultured in M2 medium omitted phenol red. Intracellular Ca2+ was checked by using a confocal laser scanning microscope and fluo-3AM by using various intracellular Ca2+ antagonists. RESULTS: In 1mM Ni2+ treated medium which contained Ca2+(1.71mM), 75.7% of the embryos showed [Ca2+]i transient about 200 sec later. In the Ca2+-free medium, 69.8% of the embryos showed [Ca2+]i transient. In U73122, phospholipaseC(PLC) inhibitor (5uM, 10min) pretreated group, 33.3% of the embryos showed [Ca2+]i transient. Heparine, inositol 1,4,5-triphosphate receptor(IP3R) antagonist preinjected embryos showed no response with 1mM Ni2+. In danthrolene treatment, ryanodine receptor(RyR)-antagonist, 43% embryos showed [Ca2+]i transient but they showed delayed response about 340sec in the presence of Ca2+. CONCLUSIONS: Summing up the above results, Ni2+ seems to induce Ca2+-release from the Ca2+-store even in the Ca2+-free medium. IP3 receptors of the mouse 2-cell embryos might have an essential role for the intracellular Ca2+ increase by Ni2+.