Somatostatin Gene Research Articles

Efficacy and safety of an oral somatostatin DNA vaccine without antibiotic resistance gene in promoting growth of piglets.

This study aimed to evaluate the efficacy and safety of an oral DNA vaccine against somatostatin (SS) (pGS/2SS-asd, encoding two copies of somatostatin genes) mediated by attenuated Salmonella choleraesuis C500 without antibiotic resistance gene on piglets growth. A total of 50 piglets were uniformly divided into five groups. The animals in the first three groups were orally given vaccine in dose of either 5 9 1010, 5 9 109 or 5 9 108 colony-forming units (CFU).The remaining two groups were orally administered with either bacteria C500(containing pVAX-asd plasmid without somatostatin gene) or phosphate buffered saline (PBS) as controls. The results indicated that the vaccine induced SS-specific antibodies in a dose-dependent pattern. Compared with the PBS control, animals in the high-dose group showed lower SS levels and higher growth hormone (GH) levels in sera. Average daily gain of animals in the high dose group was increased by 32.88% and 26.46% during 4 and 8 weeks,respectively. Anti-SS antibodies were positively correlated with either GH levels or average daily gain at week 8 after primary immunization (P < 0.05). Faecal,soil and water samples originating from immunized piglets and surrounding environment were collected. The target gene (the fusion gene GS/2SS) of C500(pGS/2SS-asd) was not detected by PCR amplification in these samples,indicating that the surrounding environment was not contaminated by residual recombinant bacteria. In conclusion, the vaccine without antibiotic resistance gene is attributable to improve growth performance of piglets through an influence on GH secretion. Moreover, the immunization did not contaminate the surrounding environment of animals.

Evaluation of efficacy, biodistribution and safety of antibiotic-free plasmid encoding somatostatin genes delivered by attenuated Salmonella enterica serovar Choleraesuis

We describe here a balanced-lethal system using an Asd+ expression plasmid pVGS/2SS-asd encoding two copies of somatostatin (SS) genes carried by Δasd/Δcrp double mutant Salmonella enterica serovar Choleraesuis (named C501). The advantage of this novel system is the use of asd (aspartate-semialdehyde dehydrogenase) gene as selection marker to replace the antibiotic resistance markers, thus eliminating the industrial cultivation and environmental problems. We then evaluated the efficacy, biodistribution and safety of antibiotic-free plasmid delivered by strains C501. Mice orally immunized with C501 (pVGS/2SS-asd) had significantly higher levels of anti-SS total IgG and IgA antibodies than control mice and demonstrated a bias toward Th2-associated responses (IgG1/IgG2a ratio>1). Safety evaluation indicated that vaccinated mice displayed no abnormal clinical signs and histological changes. Biodistribution result revealed that the GS/2SS message was detected in several examined tissues with the exception of ovary and brain, but was rapidly cleared from the body (approximately 10 days). Furthermore, the risk of integration of plasmid pVGS/2SS-asd into the host cellular genome was considered to be negligible. These results may have important implications for the use of vaccine strain C501 (pVGS/2SS-asd) in domestic animals and prompt new perspectives on the safety of DNA vaccines delivered by attenuated bacteria.

Mechanisms of actions of somatostatin on the regulation of pituitary growth hormone release in fish

Somatostatin is a multifunctional tetradecapeptide which is involved in growth,development, metabolism and reproductive processes,via the specific seven α helical transmembrane G-protein-coupled receptors( GPCRs). This review briefly summarizes the progress of research on somatostatin and its receptors,w ith special emphasis on the intracellular signaling mechanisms mediating somatostatin actions on the regulation of pituitary grow th hormone release in fish. To date,six somatostatin genes and four somatostatin receptors have been characterized in fish. The diversity of the somatostatin peptide family is due to the existence of multiple somatostatin genes as w ell as the tissue-specific differential processing of preprosomatostatin. The subtypes of somatostatin receptors are complex due to the polyploidization that occurred during fish lineage evolution. Information on the mechanisms of somatostatin suppression of GH secretion in teleosts is mainly derived from studies in goldfish,w hich indicates that cAMP formation,Ca2 + mobilization,and PKC activation may be involved in the mechanism through w hich somatostatin regulates GH secretion. How ever,the intricate w eb of intracellular signals is still far from being fully understood. In addition,species-specific differences in the mechanisms of GH release do exist in diverse models. The somatostatin genes,receptors and the mechanism of actions of somatostatin on pituitary GH release aw ait further studies in teleosts.

Construction and immunogenicity of recombinant porcine circovirus-like particles displaying somatostatin

In order to obtain a virus-like particles (VLPs) vaccine both for porcine circovirus type 2 (PCV2) prevention and growth-promotion, somatostatin (SS) gene was fused to the 3′-terminal of ORF2 gene of PCV2 with PCR, and a recombinant baculovirus (rAc-Cap-SS) was constructed. The expression of fusion protein Cap-SS (rCap-SS) with molecular weight of approximately 32kDa was identified by Western blot and indirect immunofluorescence assay in Sf9 cells. The self-assembled VLPs were observed under electron microscopy, which being morphologically similar to the recombinant Cap protein (rCap) expressed in the same baculovirus expressing system. Ninety four-week-old mice were immunized with the recombinant proteins twice. The results showed that mice immunized with rCap-SS protein developed antibody against Cap, which levels being similar to those immunized with rCap protein. The body weight gain and anti-SS antibody in rCap-SS group was higher than those of rCap and negative control groups during 28 and 42 days post inoculation (dpi). Furthermore, twenty 28-day-old piglets were vaccinated twice subcutaneously with the recombinant proteins. The results indicated that PCV2-specific antibody could be induced after vaccination with rCap-SS or rCap protein. Anti-SS antibody could be induced after rCap-SS vaccination and was higher than other groups at 14 and 28 dpi. The level of somatostatin concentration in the blood of pigs in rCap-SS group was significantly decreased at 14 dpi than other groups (P<0.05). The relative daily weight gain (RDWG) of pigs in rCap-SS group was obviously higher than that in other groups at 28 dpi. After challenge with PCV2, pigs in the vaccinated groups had no clearly clinical signs, and the RDWG was significantly higher than that in the challenge control group (CC) (P<0.05). The pathological lesions, viremia and viral load presented in the vaccinated groups were milder than those in challenge control group. It suggested that the recombinant porcine circovirus-like particles displaying somatostatin might be a novel subunit vaccine candidate for preventing PMWS and promoting pig growth.

Molecular cloning of the cDNAs encoding three somatostatin variants in the dogfish (Scylorhinus canicula)

It has been recently shown that the somatostatin gene family was likely composed of at least three paralogous genes in the common ancestor of all extant jawed vertebrates. These three genes, namely SS1, SS2 and SS5, are thought to have been generated through the two rounds of whole-genome duplications (2R) that took place early during the vertebrate evolution. In the present study, we report the cloning of three distinct somatostatin cDNAs from the dogfish Scylorhinus canicula, a member of the group of cartilaginous fish. We decided to call these cDNAs, at least provisionally, SSa, SSb and SSc, respectively. Two of them, SSa and SSb, encode proteins that both contain the same tetradecapeptide sequence at their C-terminal extremity (AGCKNFFWKTFTSC). This putative peptide is identical to that generated by the SS1 gene in other vertebrate species. The last cDNA, SSc, encodes a protein that contains at its C-terminal extremity the same peptide sequence as that generated by the SS2 gene in teleosts (APCKNFFWKTFTSC). Phylogenetic analysis showed that the SSa and SSc genes likely correspond to the dogfish counterparts of the SS1 and SS2 genes, respectively. In contrast, the phylogenetic status of the SSb gene is less clear. Several lines of evidence suggest that it could correspond to the SS5 gene, but this view will need to be confirmed, for example by synteny analysis. Finally, RT-PCR analysis revealed that SSa, SSb and SSc genes are differentially expressed in dogfish tissues, suggesting that the corresponding peptides may exert distinct functions.

202 Hydrogen Sulfide (H2S) Inhibits Bile Acid Receptor TGR5-Mediated GLP-1 Release From Enteroendrocrine Cells: Possible Involvement of H2S in Altered Glucose Metabolism in Diabetes

G A A b st ra ct s gene expression was lower in the Ift88ΔS mice. Despite the rapid induction of gastrin secretion, Ift88ΔS mice showed delayed induction of acid secretion with food intake, and lower mRNA levels of both H+K+ATPase α and β-subunits. In these mice, gastrin, ghrelin, and somatostatin gene expression did not change in response to food intake as in controls. At age 5 months, Ift88ΔS stomachs were histologically normal. However when analyzed at 8 months, mice developed gastric pathology associated with endocrine dysfunction including foveolar hyperplasia, hypergastrinemia, and hypochlorhydria. Epithelial deletion of Kif3a, another gene required for cilia formation, recapitulated the phenotypes observed in Ift88ΔS mice. Conclusion: Overall, our results demonstrated that gastric epithelial cilia regulate endocrine cell function and gastric homeostasis by sensing luminal food.

Protein Implicated in Nonsyndromic Mental Retardation Regulates Protein Kinase A (PKA) Activity

Mutation of the coiled-coil and C2 domain-containing 1A (CC2D1A) gene, which encodes a C2 domain and DM14 domain-containing protein, has been linked to severe autosomal recessive nonsyndromic mental retardation. Using a mouse model that produces a truncated form of CC2D1A that lacks the C2 domain and three of the four DM14 domains, we show that CC2D1A is important for neuronal differentiation and brain development. CC2D1A mutant neurons are hypersensitive to stress and have a reduced capacity to form dendrites and synapses in culture. At the biochemical level, CC2D1A transduces signals to the cyclic adenosine 3',5'-monophosphate (cAMP)-protein kinase A (PKA) pathway during neuronal cell differentiation. PKA activity is compromised, and the translocation of its catalytic subunit to the nucleus is also defective in CC2D1A mutant cells. Consistently, phosphorylation of the PKA target cAMP-responsive element-binding protein, at serine 133, is nearly abolished in CC2D1A mutant cells. The defects in cAMP/PKA signaling were observed in fibroblast, macrophage, and neuronal primary cells derived from the CC2D1A KO mice. CC2D1A associates with the cAMP-PKA complex following forskolin treatment and accumulates in vesicles or on the plasma membrane in wild-type cells, suggesting that CC2D1A may recruit the PKA complex to the membrane to facilitate signal transduction. Together, our data show that CC2D1A is an important regulator of the cAMP/PKA signaling pathway, which may be the underlying cause for impaired mental function in nonsyndromic mental retardation patients with CC2D1A mutation.

Neuronostatin, a Novel Peptide Encoded by Somatostatin Gene, Regulates Cardiac Contractile Function and Cardiomyocyte Survival

Neuronostatin, a recently discovered peptide encoded by somatostatin gene, is involved in regulation of neuronal function, blood pressure, food intake, and drinking behavior. However, the biological effects of neuronostatin on cardiac myocytes are not known, and the intracellular signaling mechanisms induced by neuronostatin remain unidentified. We analyzed the effect of neuronostatin in isolated perfused rat hearts and in cultured primary cardiomyocytes. Neuronostatin infusion alone had no effect on left ventricular (LV) contractile function or on isoprenaline- or preload-induced increase in cardiac contractility. However, infusion of neuronostatin significantly decreased the positive inotropic response to endothelin-1 (ET-1). This was associated with an increase in phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK). Treatment of both neonatal and adult cardiomyocytes with neuronostatin resulted in reduced cardiomyocyte viability. Inhibition of JNK further increased the neuronostatin-induced cell death. We conclude that neuronostatin regulates cardiac contractile function and cardiomyocyte survival. Receptors for neuronostatin need to be identified to further characterize the biological functions of the peptide.

Cloning, tissue expression of three somatostatin genes of Siniperca chuatsi and their localizations in brain

Somatostatins(SS)play important physiological functions in vertebrate's growth and development,which belong to a multiple gene family.In this study,the complete cDNA sequences of three distinct preprosomatostatins(PSSⅠ,PSSⅡand PSSⅢ)were isolated from Siniperca chuatsi brain and cloned by means of rapid amplification of cDNA ends(RACE).The full length of PSSⅠ cDNA was 647 bp,which contained 369 bp open reading frame and encoded 122 amino acids with a signal peptide of 26 amino acids.It contained the conservative SS-14 sequence at the C-terminal extremity,which is identical with that of other vertebrates.The full length of PSSⅡ cDNA was 655 bp,which contained 387 bp open reading frame and encoded 128 amino acids with a signal peptide of 25 amino acids.It contained[Tyr7,Gly10]SS-14 at the C-terminal extremity.The full length of PSSⅢ cDNA was 823 bp,which contained 333 bp open reading frame and encoded 110 amino acids with a signal peptide of 21 amino acids.It containedSS-14 at its C-terminal extremity.PSS mRNA expressions in different adult tissues were analyzed by RT-PCR technique.All PSS mRNA were found in brain,while PSSⅠ mRNA wasn't detected in other peripheral tissues,high levels of PSSⅡ mRNA were also present in esophagus and stomach,PSSⅢ mRNA in kidney and gonad.These suggested that all PSSs participate in neurological regulation in brain,whereas PSSⅡ may also regulate digestion activity,and PSSⅢ regulates reproduction activity.Cellular localization of PSS mRNAs in brain was determined by in situ hybridization,PSSⅠ mRNA was expressed in hypothalamus and medulla oblongata,PSSⅡ mRNA was expressed in hypothalamus,PSSⅢ mRNA was expressed in hypothalamus,optic tectun,medulla oblongata and spinal cord.All PSS mRNA were detected in the hypothalamus,which showed they could be involved in hypothalamic-pituitary regulation.Distinct expression in other brain sections suggested somatostatins may also act as neurotransmitters or hormones,and exhibit different biological effects.

Expression and cellular localization of somatostatin fromParalichthys olivaceus

Somatostatin(SS) called also somatotropin release-inhibiting factor is a peptide named for its ability to inhibit pituitary growth hormone release.To facilitate investigation of the SS function in the teleost,its coding sequence in paralichthys olivaceus was isolated by the technique of Rapid Amplification of cDNA Ends(RACE).SYBR Green I Quantitative Real-time PCR analysis and immunohistochemistry were used to assess the expression of SS at mRNA and protein level.The deduced protein sequence con-tains 126 amino acid residues and a predicted molecular mass of 14.3 kD.Very low level of SS mRNA is presented during the first three days after hatching.The expression level of the SS gene was increased con-stantly before metamorphosis and steadily during the metamorphosis,then increased significantly during post-metamorphosis.There was no SS-positive reaction in the oropharyngeal cavity and esophagus.SS secreting cells are only distributed in the stomach,pancreas and pituitary.Several types of SS secreting cells could be distinguished in above organs.In stomach,SS secreting cells are dispersively distributed among the epithelium cells,presenting various kinds of forms such as ovoid,globular,triangle,elongated or spindle-shaped aspects.The pancreas and liver of flounder combine into a single organ named hepato-pancreas,and SS-positive cells are only located in the pancreas,showing as globular-shaped,most of them are closed to blood vessels.SS-positive cells at high density are located in pars distalis of pituitary,so it is difficult to distinguish the shape of those cells.

Neuronostatin induces hyperalgesia in formalin test in mice

Neuronostatin, a newly identified peptide encoded by the somatostatin (SST) gene, was proved to produce significant antinociceptive effect in mouse tail immersion test. However, the effect of neuronostatin on tonic pain was still not clear. The aim of this study was to investigate the effect of neuronostatin in the formalin test and its possible mechanism. We found that intracerebroventricular (i.c.v.) administration of neuronostatin (1, 3, 6, 12 nmol/mouse) increased licking in a dose-related manner during the late phase, but did not affect the early phase of formalin test in mice. In addition, the hyperalgesic effect during the late phase was completely reversed by melanocortin 3/4 receptor antagonist SHU9119 (50 pmol/mouse) or opioid receptor antagonist naloxone (5 nmol/mouse), but not GABAA receptor antagonist bicuculline (1086 pmol/mouse). These data suggested that the hyperalgesic response induced by neuronostatin was dependent upon the central melanocortin system and endogenous opioid system. In conclusion, these results indicated that neuronostatin may be a new neuropeptide with important role in the modulation of acute and tonic pain.

Epigenetic control of somatostatin and cortistatin expression by β amyloid peptide

β Amyloid, present in senile plaques, has been related largely to neuronal loss in the brain of patients with Alzheimer's disease. However, how neurons respond to β amyloid insults is still poorly understood. Here we show that β amyloid increases somatostatin and cortistatin gene expression mainly through an increase in histone 3 lysine 4 methylation (H3K4me3), a modification associated with transcriptional activation. Somatostatin and cortistatin partially decreased β amyloid toxicity in primary cortical neurons in culture. Thus we suggest that neurons respond to β amyloid insults by releasing somatostatin and cortistatin, which will act as a protective agent against β amyloid toxicity. Our results suggest a relevant function for both neuropeptides against β amyloid toxicity, providing new insights into Alzheimer's disease.

Nkx2.2 and Arx genetically interact to regulate pancreatic endocrine cell development and endocrine hormone expression

Nkx2.2 and Arx are essential pancreatic transcription factors. Nkx2.2 is necessary for the appropriate specification of the islet alpha, beta, PP and epsilon cell lineages, whereas Arx is required to form the correct ratio of alpha, beta, delta and PP cells. To begin to understand the cooperative functions of Nkx2.2 and Arx in the development of endocrine cell lineages, we generated progenitor cell-specific deletions of Arx on the Nkx2.2 null background. The analysis of these mutants demonstrates that expansion of the ghrelin cell population in the Nkx2.2 null pancreas is not dependent on Arx; however, Arx is necessary for the upregulation of ghrelin mRNA levels in Nkx2.2 mutant epsilon cells. Alternatively, in the absence of Arx, delta cell numbers are increased and Nkx2.2 becomes essential for the repression of somatostatin gene expression. Interestingly, the dysregulation of ghrelin and somatostatin expression in the Nkx2.2/Arx compound mutant (Nkx2.2null;ArxΔpanc) results in the appearance of ghrelin+/somatostatin+ co-expressing cells. These compound mutants also revealed a genetic interaction between Nkx2.2 and Arx in the regulation of the PP cell lineage; the PP cell population is reduced when Nkx2.2 is deleted but is restored back to wildtype numbers in the Nkx2.2null;ArxΔpanc mutant. Moreover, conditional deletion of Arx in specific pancreatic cell populations established that the functions of Arx are necessary in the Neurog3+ endocrine progenitors. Together, these experiments identify novel genetic interactions between Nkx2.2 and Arx within the endocrine progenitor cells that ensure the correct specification and regulation of endocrine hormone-producing cells.

Tumor Suppressor Menin Represses Paired Box Gene 2 Expression via Wilms Tumor Suppressor Protein-Polycomb Group Complex

Tumor suppressor menin, the product of the MEN1 gene, plays a key role in controlling histone 3 lysine 4 trimethylation (H3K4me3) and gene transcription, which can regulate proliferation, apoptosis, and differentiation. However, little is known as to whether menin controls gene expression and cell proliferation and survival via regulating Polycomb group (PcG) protein complex/H3K27me3. Here we show that menin specifically represses transcription factor Paired box gene 2 (Pax2) through PcG-mediated H3K27me3 and Wilms tumor suppressor protein (WT1), a zinc finger domain-containing DNA-binding protein. Menin does not directly bind to the Pax2 locus, instead, it up-regulates WT1 expression. WT1 recruits PcG complex to the Pax2 promoter and represses expression of Pax2 through PcG-dependent H3K27me3. Moreover, WT1 also interacts with DNA methyltransferase 1 (DNMT1), and recruits DNMT1 to the Pax2 promoter, resulting in hypermethylation of CpG in the Pax2 promoter. Together, these studies have uncovered a novel epigenetic mechanism whereby menin regulates H3K27me3 and promoter DNA methylation via WT1 and suggest that WT1 protein plays an important, yet previously unappreciated role in regulating the function of the menin/PcG axis, H3K27 methylation, and DNA methylation, resulting in repression of gene transcription.

Polymorphism of somatostatin gene and its association with growth traits in Chinese cattle

Somatostatins play a crucial role in the regulation of growth and development in vertebrates, especially muscle growth. We assessed the association of somatostatin gene polymorphisms with growth traits by PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism) and DNA sequencing methods in 694 individuals from six Chinese cattle breeds. A novel single nucleotide polymorphism, G126A, was detected, and significant associations were found with body length, body height, hip width, heart girth, and hucklebone width index. Polymorphism of the somatostatin gene was found to be highly associated with growth traits in the Qinchuan breed at various ages. Gene frequency analysis showed significant differences among the breeds. Individuals with genotype AA had significantly lower body height, body length, hip width, and hucklebone width values compared to AG at 1.5 years old, and had significantly lower hip width, body length and hucklebone width compared to AG at 2 years old. At 2.5 years old, populations with genotype AA had significantly lower body length, hip width and hucklebone width than AG individuals, with the exception of the Luxi breed, in which two genotypes were found. The Luxi and Ximentaer crossbreed had the lowest frequency of the G allele, while the highest G allele frequencies were found in the Luxi breed.

Topography of somatostatin gene expression relative to molecular progenitor domains during ontogeny of the mouse hypothalamus

The hypothalamus comprises alar, basal, and floor plate developmental compartments. Recent molecular data support a rostrocaudal subdivision into rostral (terminal) and caudal (peduncular) halves. In this context, the distribution of neuronal populations expressing somatostatin (Sst) mRNA was analyzed in the developing mouse hypothalamus, comparing with the expression pattern of the genes Orthopedia (Otp), Distal-less 5 (Dlx5), Sonic Hedgehog (Shh), and Nk2 homeobox 1 (Nkx2.1). At embryonic day 10.5 (E10.5), Sst mRNA was first detectable in the anterobasal nucleus, a Nkx2.1-, Shh-, and Otp-positive basal domain. By E13.5, nascent Sst expression was also related to two additional Otp-positive domains within the alar plate and one in the basal plate. In the alar plate, Sst-positive cells were observed in rostral and caudal ventral subdomains of the Otp-positive paraventricular complex. An additional basal Sst-expressing cell group was found within a longitudinal Otp-positive periretromamillary band that separates the retromamillary area from tuberal areas. Apart of subsequent growth of these initial populations, at E13.5 and E15.5 some Sst-positive derivatives migrate tangentially into neighboring regions. A subset of cells produced at the anterobasal nucleus disperses ventralward into the shell of the ventromedial hypothalamic nucleus and the arcuate nucleus. Cells from the rostroventral paraventricular subdomain reach the suboptic nucleus, whereas a caudal contingent migrates radially into lateral paraventricular, perifornical, and entopeduncular nuclei. Our data provide a topologic map of molecularly defined progenitor areas originating a specific neuron type during early hypothalamic development. Identification of four main separate sources helps to understand causally its complex adult organization.

SIK2 Is a Key Regulator for Neuronal Survival after Ischemia via TORC1-CREB

The cAMP responsive element-binding protein (CREB) functions in a broad array of biological and pathophysiological processes. We found that salt-inducible kinase 2 (SIK2) was abundantly expressed in neurons and suppressed CREB-mediated gene expression after oxygen-glucose deprivation (OGD). OGD induced the degradation of SIK2 protein concomitantly with the dephosphorylation of the CREB-specific coactivator transducer of regulated CREB activity 1 (TORC1), resulting in the activation of CREB and its downstream gene targets. Ca(2+)/calmodulin-dependent protein kinase I/IV are capable of phosphorylating SIK2 at Thr484, resulting in SIK2 degradation in cortical neurons. Neuronal survival after OGD was significantly increased in neurons isolated from sik2(-/-) mice, and ischemic neuronal injury was significantly reduced in the brains of sik2(-)(/-) mice subjected to transient focal ischemia. These findings suggest that SIK2 plays critical roles in neuronal survival, is modulated by CaMK I/IV, and regulates CREB via TORC1.

Regulation of somatostatin gene expression by brain derived neurotrophic factor in fetal rat cerebrocortical cells

Brain derived neurotrophic factor (BDNF) increases the levels of somatostatin (SS) and its mRNA. To test the hypothesis that the regulation of SS synthesis by BDNF occurs at the transcriptional level and requires specific promoter sequences, cerebrocortical and PC12trkB neurons were transiently transfected with different constructs of the SS promoter fused to the luciferase and CAT reporter genes. We demonstrated that BDNF triggered the transcription of the SS gene through the CRE sequence located in the SS promoter. BDNF and SS are genes regulated by K +-induced neuronal activity. Using BDNF blocking antibodies, we investigated whether K +-induced BDNF was required for K +-dependent SS mRNA induction. We found that K +-induced SS mRNA was partially prevented when BDNF was blocked. This finding indicated that BDNF mediated the induction of SS mRNA by K + depolarization. To identify the mechanisms by which BDNF activates SS gene transcription we first elucidated the signaling pathways activated by BDNF in cerebrocortical cells. We confirmed that BDNF activates the MAPK/ERKs and PI3K/Akt pathways. Both signaling pathways are, in turn, implicated in the activation of CREB by BDNF. In addition we observed that the PKA inhibitors, H89 and Rp-cAMPS decreased BDNF-induced CREB activation. These findings suggested that BDNF-induced CREB activation was also mediated by the cAMP/PKA pathway. We next elucidated the mechanism by which BDNF induces SS mRNA. We observed that H89, PD0998059, KN62 and LY294002 diminished BDNF-induced SS mRNA suggesting that BDNF-induced SS mRNA is mediated by the activation of cAMP/PKA, MAPK/ERKs, CaMK and PI3K pathways.

Effects of immunization against a DNA vaccine encoding somatostatin gene (pGM-CSF/SS) by attenuated Salmonella typhimurium on growth, reproduction and lactation in female mice

A novel somatostatin (SS) DNA vaccine (pGM-CSF/SS), delivered orally by attenuated Salmonella typhimurium (CSO22), was used to immunize female mice at 5, 7, and 11 wk of age; the objective was to investigate the humoral immune response and effects of this vaccine on growth, reproduction and lactation. The pGM-CSF/SS induced SS-specific antibodies, which peaked (3.69 ± 0.89; mean ± S.D) 4 wk after the first booster immunization. Compared with a saline-treated control group, body weight gain of a pGM-CSF/SS immunized group increased 30.3% (23.88 vs. 18.32 g, P < 0.05) during the growth period (from 2 wk after primary immunization to 4 wk after the first booster immunization). Immunized mice had higher plasma estradiol concentrations (84.10 ± 2.16 vs. 81.45 ± 2.12 pg/ml, P < 0.05) and a shorter estrous cycle (4.06 ± 0.75 vs. 5.33 ± 0.49 d, P < 0.05), but serum progesterone concentrations were not significantly affected. Since offspring produced by immunized mice gained weight faster (P < 0.05) in the first 2 wk of life (4.27 ± 0.62 and 7.81 ± 1.30 g in Weeks 1 and 2, respectively vs. 3.70 ± 0.23 and 7.14 ± 0.48 g), we inferred that pGM-CSF/SS could have a direct or indirect role in regulating lactation in mice. In conclusion, GM-CSF and CSO22 served as adjuvant and attenuated live vector, respectively, with efficient oral delivery of an SS DNA vaccine which successfully induced a humoral immune response and enhanced rate of weight gain. Furthermore, the DNA vaccine pGM-CSF/SS affected plasma estradiol concentrations and the estrous cycle, and seemed to enhance lactation performance of female mice.

Urotensin II, from fish to human

The cyclic peptide urotensin II (UII) was originally isolated from the urophysis of teleost fish on the basis of its ability to contract intestinal smooth muscle. The UII peptide has subsequently been isolated from frog brain and, later on, the pre-proUII cDNA has been characterized in mammals, including humans. A UII paralog called urotensin II-related peptide (URP) has been identified in the rat brain. The UII and URP genes originate from the same ancestral gene as the somatostatin and cortistatin genes. In the central nervous system (CNS) of tetrapods, UII is expressed primarily in motoneurons of the brainstem and spinal cord. The biological actions of UII and URP are mediated through a G protein-coupled receptor, termed UT, that exhibits high sequence similarity with the somatostatin receptors. The UT gene is widely expressed in the CNS and in peripheral organs. Consistent with the broad distribution of UT, UII and URP exert a large array of behavioral effects and regulate endocrine, cardiovascular, renal, and immune functions.