Cryopreservation of Kalopanax septemlobus embryogenic callus using vitrification and droplet-vitrification

A cryopreservation protocol has been developed for embryogenic callus cultures of castor aralia (Kalopanax septemlobus), a deciduous tree which is widely used in oriental medicine and in landscape design. Three preculture treatments, four loading and six vitrification solutions were tested in a vitrification procedure. Preculture of embryogenic callus (EC) with high sucrose concentrations (up to 0.7 M) showed no effect on regrowth after cryopreservation. Loading for 20 min at ambient temperature improved regrowth of cryopreserved EC by 70-75 percent compared with non-loaded samples, regardless of the composition of the loading solution. Among vitrification solutions, the highest regrowth of 95-100 percent after cryopreservation was obtained after incubation of EC in a vitrification solution A3-80 percent comprising (w/v) 33.3 percent glycerol + 13.3 percent DMSO + 13.3 percent EG + 20.1 percent sucrose for 40 min at 0°C. Profiling of crystallization and recrystallization events using differential scanning calorimetry (DSC) confirmed that freezing injury was minimized in samples after loading and cryoprotection with this vitrification solution. Unlike many other papers, the droplet-vitrification protocol did not produce higher post-cryopreservation regrowth of Kalopanax EC, compared with the vitrification procedure. When samples are sufficiently cryoprotected during VS treatment, vitrification using cryovials may be preferred, since droplet-vitrification is more complex and requires skilled personnel. Cryopreserved callus grew rapidly and produced numerous somatic embryos, which developed similarly to embryos obtained from non-cryopreserved samples.

Synergistic association of PTGS2 and CYP2E1 genetic polymorphisms with lung cancer risk in northeastern Chinese

BACKGROUND

Lung cancer is the most common cause of cancer-related deaths worldwide. The aim of this study was to investigate the association of five extensively-studied polymorphisms in PTGS2 (rs689466, rs5275, rs20417) and CYP2E1 (rs2031920, rs6413432) genes with lung cancer risk in a large northeastern Chinese population.

METHODOLOGY/PRINCIPAL FINDINGS

This is a hospital-based case-control study involving 684 patients with lung cancer and 604 cancer-free controls. Genotyping was performed using the PCR-LDR method. Data were analyzed using Haplo.stats and MDR programs. There were significant differences between patients and controls in allele/genotype distributions of rs5275 (P = 0.002/0.003) and rs6413432 (P = 0.037/0.044), as well as in genotype distributions of rs689466 (P = 0.02). The risk for lung cancer associated with the rs5275-C mutant allele was decreased by 60% (95% CI [confidence interval]: 0.21-0.74; P = 0.004) under the recessive model. Carriers of rs689466-G mutant allele had a 28% (95% CI: 0.57-0.92; P = 0.008) reduced risk of developing lung cancer relative to the AA genotype carriers. In haplotype analysis, haplotype G-C-C-T (in order of rs689466, rs5275, rs2031920 and rs6413432) decreased the odds of lung cancer by 28% (95% CI: 0.51-0.93; P = 0.019) after adjusting for confounding factors, whereas haplotype A-T-T-T had 1.49-fold (95% CI: 1.21-1.79; P = 0.012) increased risk for lung cancer. Using MDR method, the overall best model including rs5275, rs689466 and rs6413432 polymorphisms was identified with a maximal testing accuracy of 66.1% and a maximal cross-validation consistency of 10 out of 10 (P = 0.003).

CONCLUSIONS/SIGNIFICANCE

Our findings demonstrated a potentially synergistic association of PTGS2 and CYP2E1 polymorphisms with the underlying cause of lung cancer in northeastern Chinese.

Real-time PCR and Amplified MTD® for rapid detection of Mycobacterium tuberculosis in pulmonary specimens

SETTING

Patients with suspected pulmonary tuberculosis (PTB) in the First Affiliated Hospital, College of Medicine, Zhejiang University.

OBJECTIVE

To evaluate the 'Care TB®' real-time polymerase chain reaction (PCR) assay in comparison with the Amplified MTD® Test (AMTD) for the rapid diagnosis of TB.

DESIGN

Self-expectorated sputum was collected for direct smear microscopy, culture, real-time PCR and AMTD assay. Performance of the 'Care TB' real-time PCR and AMTD assay were compared using a combination of culture and clinical diagnosis as a reference standard.

RESULTS

Of the 178 sputum specimens, 83 were culture-positive; of these, 74 were Mycobacterium tuberculosis complex and 9 strains were non-tuberculous mycobacteria. The overall sensitivities and specificities were respectively 91.6% and 100% for real-time PCR, and 95.2% and 97.9% for AMTD. In the smear-positive specimens, the sensitivities and specificities were respectively 97% and 100% for real-time PCR, and 98.5% and 100% for AMTD. In the smear-negative specimens, the sensitivities and specificities were 70.6% and 100% for real-time PCR, and 82.4% and 97.7% for AMTD.

CONCLUSIONS

Both real-time PCR and AMTD are rapid and specific tests for detecting M. tuberculosis complex; however, 'Care TB' real-time PCR is more convenient and economical.

Overexpression of interleukin-l7 in tumor-associated macrophages is correlated with the differentiation and angiogenesis of laryngeal squamous cell carcinoma

BACKGROUND

Interleukin-l7 (IL-17), which exerts strong pro-inflammatory effects, has emerged as an important mediator in inflammation-associated cancer. The aim of this study was to clarify the relationship between IL-17 and tumor associated macrophages (TAMs), and the correlation of the microvessel density in the development of laryngeal squamous cell carcinoma (LSCC).

METHODS

Histopathological observations and immunohistochemistry staining for IL-17, CD68, and CD34 were performed on 72 specimens (32 cases of LSCC, 20 cases of adjacent tissues of carcinoma as controls, and 20 cases of chronic hypertrophic laryngitis). Double immunohistochemical staining was done to determine which cells expressed IL-17. Real-time quantitative PCR determined the mRNA expression of IL-17. ELISA was used to detect the expression of the serum level of IL-17 in the three groups.

RESULTS

The inflammation response had increased in LSCC. Overexpression of IL-17 and CD68 protein were seen in LSCC (P < 0.01). The expression of IL-17 was different between well and poorly differentiated LSCC (P < 0.01). The IL-17 expressing cells were mainly located in macrophages (CD68(+)/IL17(+)) as demonstrated by double immunohistochemical staining. IL-17 expression significantly correlated with high microvessel density (CD34(+)) in LSCC (P < 0.05). Relatively higher mRNA expression levels of IL-17 were seen in LSCC compared to the controls (P < 0.05). The serum expression of IL-17 was similar among the three groups (P > 0.05).

CONCLUSION

IL-17 was expressed by TAMs, and IL-17 may significantly correlate to the differentiation and angiogenesis in the development of LSCC.

[Role of C-type natriuretic peptide receptor and large-conductance calcium-activated potassium channels in brain natriuretic peptide-induced porcine coronary artery dilation]

OBJECTIVE

To investigate the role of C-type natriuretic peptide receptor (NPR-C) and large-conductance calcium-activated potassium channels (BK(Ca)) in brain natriuretic peptide (BNP) induced porcine coronary artery dilation.

METHODS

Porcine coronary artery rings were obtained and treated with BNP (10(-6) mol/L), BNP + NPR-C antagonist cANF4-28 (10(-6) mol/L) and BNP + BK(Ca) blocker tetraethylammonium (TEA, 1 mmol/L). The vascular tone experiments were observed on 10 vessel segments. BK(Ca) current density was measured by the whole-cell patch clamp technique.

RESULTS

The maximum diastolic rate was similar between BNP group (68.51% ± 11.50%) and cANF4-28 + BNP group (65.67% ± 11.90%, P > 0.05) while significantly reduced in TEA + BNP group (28.87% ± 4.55%, all P < 0.05). When the holding potential was set at +60 mV, the BK(Ca) current density of BNP group was (78.48 ± 5.86) pA/pF, which was significantly higher than control group [(53.84 ± 4.55) pA/pF, P < 0.05], which was equally reduced in the TEA group and TEA + BNP group [(28.80 ± 2.76) pA/pF and (30.60 ± 3.88) pA/pF respectively, all P < 0.05 vs. control group].

CONCLUSION

BNP could relax the porcine coronary arterial smooth muscles by increasing BK(Ca) current, and this effect is not mediated by NPR-C.

Msx1 mutations: how do they cause tooth agenesis?

Mutations in the transcription factors PAX9 and MSX1 cause selective tooth agenesis in humans. In tooth bud mesenchyme of mice, both proteins are required for the expression of Bmp4, which is the key signaling factor for progression to the next step of tooth development. We have previously shown that Pax9 can transactivate a 2.4-kb Bmp4 promoter construct, and that most tooth-agenesis-causing PAX9 mutations impair DNA binding and Bmp4 promoter activation. We also found that Msx1 by itself represses transcription from this proximal Bmp4 promoter, and that, in combination with Pax9, it acts as a potentiator of Pax9-induced Bmp4 transactivation. This synergism of Msx1 with Pax9 is significant, because it is currently the only documented mechanism for Msx1-mediated activation of Bmp4. In this study, we investigated whether the 5 known tooth-agenesis-causing MSX1 missense mutations disrupt this Pax9-potentiation effect, or if they lead to deficiencies in protein stability, protein-protein interactions, nuclear translocation, and DNA-binding. We found that none of the studied molecular mechanisms yielded a satisfactory explanation for the pathogenic effects of the Msx1 mutations, calling for an entirely different approach to the investigation of this step of odontogenesis on the molecular level.

The effect of Lycium barbarum polysaccharide on alcohol-induced oxidative stress in rats

The aim of this study was to investigate the effects of Lycium barbarum Polysaccharide (LBP) on alcohol-induced liver damage in rats. A total of 36 rats were divided into control, ethanol and ethanol + LBP groups. Rats in the ethanol group were fed 7 g ethanol/kg body weight by gastric infusion, three times a day, for 30 consecutive days, while rats in the control group received the same volume of physiological saline instead of ethanol, and rats in ethanol + LBP group were fed both ethanol (7 g/kg body weight) and LBP (300 mg/Kg body weight/day). Alcoholic liver injury was examined by serum ALT and AST activities, alcoholic fatty liver was assessed by lipid levels, and oxidative stress was evaluated by SOD, CAT, GSH-Px, GSH and MDA assays. In the ethanol group, a significant elevation of enzymes and lipid in serum, increased MDA level and depletion of SOD, CAT, GSH-Px and GSH in liver were observed. LBP administration significantly ameliorated liver injury, prevented the progression of alcohol-induced fatty liver, and improved the antioxidant functions when compared with the ethanol group. Histopathological examination of rat liver revealed that LBP administration protected liver cells from the damage induced by ethanol. The results suggest that LBP is a promising agent to protect the liver from hepatotoxicity and fatty liver induced by ethanol intake.

Activation of dopamine D3 receptors inhibits reward-related learning induced by cocaine

Memories of learned associations between the rewarding properties of drugs and environmental cues contribute to craving and relapse in humans. The mesocorticolimbic dopamine (DA) system is involved in reward-related learning induced by drugs of abuse. DA D3 receptors are preferentially expressed in mesocorticolimbic DA projection areas. Genetic and pharmacological studies have shown that DA D3 receptors suppress locomotor-stimulant effects of cocaine and reinstatement of cocaine-seeking behaviors. Activation of the extracellular signal-regulated kinase (ERK) induced by acute cocaine administration is also inhibited by D3 receptors. How D3 receptors modulate cocaine-induced reward-related learning and associated changes in cell signaling in reward circuits in the brain, however, have not been fully investigated. In the present study, we show that D3 receptor mutant mice exhibit potentiated acquisition of conditioned place preference (CPP) at low doses of cocaine compared to wild-type mice. Activation of ERK and CaMKIIα, but not the c-Jun N-terminal kinase and p38, in the nucleus accumbens, amygdala and prefrontal cortex is also potentiated in D3 receptor mutant mice compared to that in wild-type mice following CPP expression. These results support a model in which D3 receptors modulate reward-related learning induced by low doses of cocaine by inhibiting activation of ERK and CaMKIIα in reward circuits in the brain.

[Vasodilatory effects of CNP on aortic arteries of rabbits]

OBJECTIVE

To investigate the mechanism of vasodilatory effects of C-type natriuretic peptide (CNP).

METHODS

Tension changes in aortic rings of rabbits were recorded with the presence of CNP or C-type natriuretic peptide receptor (NPR-C) agonist (cANF4-23) after pretreatment with epinephrine (NE) or 60 mmol/L KCl. The vasodilatory effects of four types of potassium channel blocker and NPR-C antagonist (cANF4-28) were also tested.

RESULTS

A maximal vasorelaxant effects of (33.5 +/- 5.9) % and (38.4 +/- 10.6)% were recorded in the presence of 1 micromol/L CNP and cANF4-23, respectively, cANF4-28 attenuated the action of CNP [(19.8 +/- 8.3)%]. The vasorelaxant effects of CNP and cANF4-23 decreased significantly after pretreatment with 60 mmol/L KCl (P < 0.01). Glibenclamide and BaCl2 also attenuated the relaxant activities of CNP (P < 0.05). But only BaClZ decreased the vasodilatory action of cANF4-23 (P < 0.05).

CONCLUSION

The relaxant activity of CNP is mediated through three paths: NPR-B/KATP, NPR-C/KIR and NPR-C/calcium channels.

[Sodium channel changes in human atrial cells isolated from various ages]

OBJECTIVE

To investigate if the increased incidence of atrial fibrillation with age was associated with changes of Na(+) channel in atrial myocytes.

METHODS

Twenty-three patients underwent valve replacement operations were divided into adult [< 60 years, n = 15, 9 males, mean age (42.1 +/- 7.1) years] and aged group [> or = 60 years, n = 8, 5 males, mean age (63.3 +/- 3.1) years]. All patients were in normal sinus rhythm. Whole cell patch clamp techniques were used to record the Na(+) currents (I(Na)) of right auricle myocytes.

RESULTS

Both current density and time-dependent recovery of I(Na) were similar in the cells from the 2 groups. Voltage-dependent inactivation of I(Na) of myocytes in the aged atria was shifted to more positive voltages.

CONCLUSION

Current density of I(Na) was similar between the 2 age groups, and Na(+) channel might not be an important determinant for the increased incidence of atrial fibrillation in aged patients.

Aquaporin-4 maintains ependymal integrity in adult mice

Ependymal cells form the walls of the ventricles, and take part in the production of cerebrospinal fluid (CSF). Aquaporin-4 (AQP4), a predominant water channel of the brain, is restricted to basolateral plasma membranes of ependymal cells. The highly polarized expression of AQP4 suggests it may be involved in maintaining the structural and functional integrity of the ependyma. This hypothesis was validated by using adult AQP4 knockout mice generated by our laboratory [Fan Y, Zhang J, Sun XL, Gao L, Zeng XN, Ding JH, Cao C, Niu L, Hu G (2005) Sex- and region-specific alterations of basal amino acid and monoamine metabolism in the brain of aquaporin-4 knockout mice. J Neurosci Res 82:458-464]. Histological analysis showed disorganized ependymal layer of the lateral ventricle and aqueduct in AQP4-deficiency mice. A majority (92.7%) of null mice displayed reduced lateral ventricular volume, while a small fraction (7.3%) had enlarged or normal ventricular size with a narrow aqueduct. Immunohistochemistry demonstrated that AQP4 deletion resulted in decreased expression of gap junction protein connexin43 in the ependymal cells. Electron microscopy confirmed junctional complex absence at basolateral membranes of ependymocytes. Moreover, AQP4 knockout mice showed decreased CSF production and increased brain water content compared with wild-type mice. These results highlight a key role of AQP4 in maintaining the structure and function of the ependyma. In addition, variable profiles of ventricle system in adult AQP4 null mice indicate functional AQP4 polymorphisms.

Concentration control of carbon nanotubes in aqueous solution and its influence on the growth behavior of fibroblasts

This work investigated the biological influence of water-soluble multiwalled carbon nanotubes (wsMWCNTs) on fibroblast cell growth as a function of concentration control in an aqueous solution. The wsMWCNTs were prepared by an optimal procedure of ultrasonication/concentrated acids oxidation. The concentration of wsMWCNT in the solution was quantified by an established calibration line. A stable concentration of 0.3mg/ml was obtained in the surfactant-free water. The physicochemical properties of wsMWCNTs were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV/VIS/NIR spectroscopy, and dynamic light scattering (DLS). Cell proliferation and the cell cycle were examined by MTS assay, flow cytometry and TEM respectively. Experimental results showed that the oxidation degree was a key factor that determined the concentration and stability of wsMWCNTs in the aqueous solution. The wsMWCNTs were able to enter into the cells and mainly accumulated in the cytoplasm. The wsMWCNTs-induced variations in cell proliferation and the cell cycle were concentration dependent. Cells cultivated with wsMWCNTs of 0.3mg/ml underwent a dramatic apoptosis. The proliferation was clearly suppressed when the cells were cultivated with wsMWCNTs of 0.03 mg/ml. There were no obvious influences on cell proliferation and the cell cycle when the concentration of wsMWNTs decreased to 0.01 mg/ml.

[The expression of Galectin-3 and VEGF in laryngeal squamous cell carcinoma]

OBJECTIVE

To investigate the expression of galectin-3 and VEGF in laryngeal squamous cell carcinoma (LSCC) tissue and to analyze its role in differentiation, growth and metastasis of the tumor.

METHOD

The expression of galectin-3 and VEGF were detected with SP immunohistochemistry staining and western blot in twenty-nine specimens of LSCC and eighteen specimens of laryngeal benign lesion.

RESULT

The expression of galectin-3 (89.7%) and VEGF (86.2%) in LSCC were remarkably higher than that in normal control tissue (P<0.05), and the expression of galectin-3 (89.7%) and VEGF (86.2%) in higher histodifferentiation specimens were higher than that in lower histodifferentiation specimens (P<0.05). Moreover, the expression level of galectin-3 and VEGF was detected a statistical positive correlation (r=0.423, P<0.05) in LSCC.

CONCLUSION

The high level expression of galectin-3 and VEGF in LSCC could play an important role in tumorous histodifferentiation and metastasis.

[Effects of minimal persistent inflammation on nasal mucosa of experimental allergic rhinitis in guinea pigs]

OBJECTIVE

To establish an animal model of minimal persistent inflammation (MPI) of allergic rhinitis in guinea pigs and to investigate the changes of nasal mucosa. The expression of transforming growth factor-beta1 (TGF-beta1) and matrix metalloproteinases-9 (MMP-9) were discussed.

METHODS

Thirty male Hartley guinea pigs were randomly divided into two groups: MPI model group and control group randomly, with fifteen animals in each group. Guinea pigs from MPI model group were sensitized intraperitoneally by injection of suspension of ovalbumin (OVA) and aluminum hydroxide in 0.9% physiological saline. Then, repeated local booster sensitization with low concentration of OVA suspension into the nasal cavity was performed to establish MPI models. Alcian blue-periodic acid-Schiff (AB-PAS) staining and Masson's trichrome (MT) staining were used to determine the number of goblet cells and collagen deposition within the basement membrane of epithelium. The expression and distribution of TGF-beta1 and MMP-9 in nasal mucosa were estimated by double immunofluorescence under a confocal laser scan microscopy system.

RESULTS

Compared with the control group, the increased goblet cells (t = 13.720, P < 0.05) in nasal epithelium together with the increased collagen fibrils (t = 4.542, P <0.05) within the basement membrane of epithelium were observed in the MPI model group. There was nearly no expression of TGF-beta1, in the control group and the expression of MMP-9 was only found in the epithelium cell. In contrast, there was significantly higher expression of TGF-beta1 and MMP-9 (t = 25.218, P <0.05) in nasal mucosa of MPI model group than that in control group. TGF-beta1 mainly expressed in the epithelium cell, the infiltrated inflammatory cell and extracellular matrix, while MMP-9 expressed in the epithelium cell and the infiltrated inflammatory cell.

CONCLUSIONS

Long time MPI in allergic rhinitis resulted in some changes of tissue remodeling in nasal mucosa. TGF-beta1 and MMP-9 may play an important role in disease progression.

[Establishment and significance of the experimental minimal persistent inflammation models in allergic rhinitis guinea pigs]

OBJECTIVE

To develop an animal model of minimal persistent inflammation (MPI) in allergic rhinitis guinea pigs and to investigate its significance.

METHODS

Sixty male Hartley guinea pigs were divided into four groups: group A (positive control group), B (MPI model group), C (negative group) and D (bland group) respectively, with fifteen animals in each group. Guinea pigs from group A, B and C were sensitized intraperitoneally by injection of suspension of ovalbumin (OVA) and aluminum hydroxide in 0.9% physiological saline. Then, repeated local booster sensitization with different concentration of OVA suspension (1% and 0.01%) or physiological saline into the nasal cavity of those guinea pigs were performed. For group D, physiological saline was used only. Symptoms (sneezing) of guinea pigs after antigen challenge were observed and the infiltration of eosinophils (EOS) together with the expression of intercellular adhesion molecule 1 (ICAM-1) in the nasal epithelial cells were also examined.

RESULTS

When challenged with 1% OVA, the sneezing number of guinea pigs in group B was increased markedly than that in group D (P < 0.05). However, there was no difference between group B, A and C (P > 0.05). When challenged with 0.01% OVA, the symptom of sneezing almost disappeared in group B just like that in group D and there was no difference between the two groups (P > 0.05). Besides, there was still more EOS infiltrated in the nasal mucosa of guinea pigs in group B than that in group D (P < 0.05). There was no expression of ICAM-1 in nasal epithelium of guinea pigs in group D, nevertheless, ICAM-1 was found mildly expressed in group B.

CONCLUSIONS

MPI models have been established successfully through long term challenge with lower density of OVA in the sensitized guinea pigs, which will provide us with a new method for further research in the mechanism and treatment of allergic rhinitis.

Interaction of somatostatin receptors with G proteins and cellular effector systems

Somatostatin induces its multiple biological actions by interacting with a family of receptors, referred to as sstr1-sstr5. To determine the molecular mechanisms of action of somatostatin, we have investigated the interaction of the different cloned receptors with G proteins and cellular effector systems. sstr2, sstr3 and sstr5 associate with pertussis toxin-sensitive G proteins and are able to mediate the inhibition of adenylyl cyclase activity by somatostatin. Two forms of sstr2, sstr2A and sstr2B, are generated by alternative splicing and differ in their C-terminal amino acid sequence. sstr2B couples to adenylyl cyclase whereas sstr2A does not. To investigate the basis for the differential coupling to adenylyl cyclase, we truncated sstr2B to the point of amino acid sequence divergence from sstr2A. The truncated sstr2B mediated the inhibition of cAMP formation by somatostatin, indicating that the C-terminus is not needed for coupling sstr2 to adenylyl cyclase. It is likely that the C-terminus of sstr2A hinders coupling to adenylyl cyclase. sstr2A associates with Gi alpha 3 and G(o) alpha but does not effectively interact with Gi alpha 1, a G protein that is necessary for coupling somatostatin receptors to adenylyl cyclase. The differential association of the splice variants with Gi alpha 1 may explain their contrasting effects on adenylyl cyclase activity. sstr3 also couples to adenylyl cyclase. Gi alpha 1 links sstr3 to adenylyl cyclase and mutagenesis studies have shown that the C-terminus of Gi alpha 1 is necessary for this coupling. The C-terminus of the Gi alpha proteins differ by only a few amino acid residues and only Gi alpha 1 couples sstr3 to adenylyl cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular biology of somatostatin receptors

The diverse physiological effects of somatostatin are mediated by a family of cell surface receptors that bind somatostatin selectively and with high affinity. The somatostatin receptors are members of the seven transmembrane segment receptor superfamily and molecular cloning studies have identified five types, designated sstr1-5. The human somatostatin receptors vary in size from 364 (sstr5) to 418 (sstr3) amino acids with 46-61% amino acid identity between receptors, and 105 amino acids are invariant. The sequences of the seven putative alpha-helical membrane-spanning domains are more highly conserved than those of the extracellular N- and intracellular C-terminal domains. Two forms of sstr2 have been identified in the mouse, sstr2A and sstr2B, which differ in size and sequence of the intracellular C-terminal domain. These two forms of sstr2 are products of a common gene and are generated by alternative splicing with sstr2A and sstr2B being the products of the unspliced and spliced forms, respectively, of sstr2 mRNA. Thus, functional diversity within the somatostatin receptor family may result from the expression of multiple types as well as from alternative splicing. The five somatostatin receptors have distinct patterns of expression in the central nervous system and peripheral tissues. They have also been expressed in vitro and shown to have different pharmacological properties. Somatostatin analogues selective for sstr2, sstr3 and sstr5 have been identified which will facilitate in vivo studies of the functions of these somatostatin receptors. Such studies to date suggest that sstr2 mediates inhibition of growth hormone secretion and sstr5 mediates inhibition of insulin secretion. The molecular cloning and functional characterization of the somatostatin receptor family is a first step in elucidating the diverse effects of somatostatin on cellular functions.

Amyloid-beta-(1-42) increases ryanodine receptor-3 expression and function in neurons of TgCRND8 mice

Disruption of intracellular calcium homeostasis precedes the neurodegeneration that occurs in Alzheimer disease (AD). Of the many neuronal calcium-regulating proteins, we focused on endoplasmic reticulum (ER)-resident ryanodine receptors (RyRs) because they are increased in the hippocampus of mice expressing mutant presenilin-1 and are associated with neurotoxicity. Others have observed that ryanodine binding is elevated in human postmortem hippocampal regions suggesting that RyR(s) are involved in AD pathogenesis. Here we report that extracellular amyloid-beta(Abeta)-(1-42) specifically increased RyR-3, but not RyR-1 or RyR-2, gene expression in cortical neurons from C57Bl6 mice. Furthermore, endogenously produced Abeta-(1-42) increased RyR-3 mRNA and protein in cortical neurons from transgenic (Tg)CRND8 mice, a mouse model of AD. Increased RyR-3 mRNA and protein was also observed in brain tissue from 4- to 4.5-month-old Tg animals compared with non-Tg littermate controls. In experiments performed in nominal extracellular calcium, neurons from Tg mice had significant increases in intracellular calcium following ryanodine or glutamate treatment compared with littermate controls, which was abolished by treatment with small interfering RNA directed to RyR-3, indicating that the higher levels of calcium originated from RyR-3-regulated stores. Taken together, these observations suggest that Abeta-(1-42)-mediated changes in intracellular calcium homeostasis is regulated in part through a direct increase of RyR-3 expression and function.