Transcriptomic Insights into Archaeal Nitrification in the Amundsen Sea Polynya, Antarctica

Antarctic polynyas have the highest Southern Ocean summer primary productivity, and due to anthropogenic climate change, these areas have formed faster recently. Ammonia-oxidizing archaea (AOA) are among the most ubiquitous and abundant microorganisms in the ocean and play a primary role in the global nitrogen cycle. We utilized metagenomics and metatranscriptomics to gain insights into the physiology and metabolism of AOA in polar oceans, which are associated with ecosystem functioning. A polar-specific ecotype of AOA, from the "Candidatus Nitrosomarinus"-like group, was observed to be dominant in the Amundsen Sea Polynya (ASP), West Antarctica, during a succession of summer phytoplankton blooms. AOA had the highest transcriptional activity among prokaryotes during the bloom decline phase (DC). Metatranscriptomic analysis of key genes involved in ammonia oxidation, carbon fixation, transport, and cell division indicated that this polar AOA ecotype was actively involved in nitrification in the bloom DC in the ASP. This study revealed the physiological and metabolic traits of this key polar-type AOA in response to phytoplankton blooms in the ASP and provided insights into AOA functions in polar oceans.

RNA outperforms DNA-based metabarcoding in assessing the diversity and response of microeukaryotes to environmental variables in the Arctic Ocean

The Arctic Ocean (AO) has a harsh environment characterized by low temperatures, extensive ice coverage, and periodic freezing and melting of sea ice, which has provided diverse habitats for microorganisms. Prior studies primarily focused on microeukaryote communities in the upper water or sea ice based on environmental DNA, leaving the composition of active microeukaryotes in the diverse AO environments largely unknown. This study provided a vertical assessment of microeukaryote communities in the AO from snow and ice to sea water at a depth of 1670 m using high-throughput sequencing of co-extracted DNA and RNA. RNA extracts depicted microeukaryote community structure and intergroup correlations more accurately and responded more sensitively to environmental conditions than those derived from DNA. Using RNA:DNA ratios as a proxy for relative activity of major taxonomic groups, the metabolic activities of major microeukaryote groups were determined along depth. Analysis of co-occurrence networks showed that parasitism between Syndiniales and dinoflagellates/ciliates in the deep ocean may be significant. This study increased our knowledge of the diversity of active microeukaryote communities and highlighted the importance of using RNA-based sequencing over DNA-based sequencing to examine the relationship between microeukaryote assemblages and the responses of microeukaryotes to environmental variables in the AO.

Spatial dynamics of active microeukaryotes along a latitudinal gradient: Diversity, assembly process, and co-occurrence relationships

Recent global warming is profoundly and increasingly influencing the Arctic ecosystem. Understanding how microeukaryote communities respond to changes in the Arctic Ocean is crucial for understanding their roles in the biogeochemical cycles of nutrients and elements. Between July 22 and August 19, 2016, during cruise ARA07, seawater samples were collected along a latitudinal transect extending from the East Sea of Korea to the central Arctic Ocean. Environmental RNA was extracted and the V4 hypervariable regions of the reverse transcribed SSU rRNA were amplified. The sequences generated by high throughput sequencing were clustered into zero-radius OTUs (ZOTUs), and the taxonomic identities of each ZOTU were assigned using SINTAX against the PR2 database. Thus, the diversity, community composition, and co-occurrence networks of size fractionated microeukaryotes were revealed. The present study found: 1) the alpha diversity of pico- and nano-sized microeukaryotes showed a latitudinal diversity gradient; 2) three distinct communities were identified, i.e., the Leg-A, Leg-B surface, and Leg-B subsurface chlorophyll a maximum (SCM) groups; 3) distinct network structure and composition were found in the three groups; and 4) water temperature was identified as the primary factor driving both the alpha and beta diversities of microeukaryotes. This study conducted a comprehensive and systematic survey of active microeukaryotes along a latitudinal gradient, elucidated the diversity, community composition, co-occurrence relationships, and community assembly processes among major microeukaryote assemblages, and will help shed more light on our understanding of the responses of microeukaryote communities to the changing Arctic Ocean.

Contrasting Community Composition and Co-Occurrence Relationships of the Active Pico-Sized Haptophytes in the Surface and Subsurface Chlorophyll Maximum Layers of the Arctic Ocean in Summer

Haptophytes (Hacrobia: Haptophyta), which can perform phototrophic, phagotrophic, or mixotrophic nutritional modes, are critical for element cycling in a variety of aquatic ecosystems. However, their diversity, particularly in the changing Arctic Ocean (AO), remains largely unknown. In the present study, the biodiversity, community composition, and co-occurrence networks of pico-sized haptophytes in the surface water and subsurface chlorophyll maximum (SCM) layer of the AO were explored. Our results found higher alpha diversity estimates in the surface water compared with in the SCM based on high-throughput sequencing of haptophyte specific 18S rRNA. The community composition of the surface water was significantly different from that of the SCM, and water temperature was identified as the primary factor shaping the community compositions. Prymnesiales (mostly Chrysochromulina), uncultured Prymnesiophyceae, and Phaeocystis dominated the surface water communities, whereas Phaeocystis dominated the SCM communities, followed by Chrysochromulina, uncultured Prymnesiophyceae, and the remaining taxa. The communities of the surface water and SCM layer developed relatively independent modules in the metacommunity network. Nodes in the surface water were more closely connected to one another than those in the SCM. Network stability analysis revealed that surface water networks were more stable than SCM networks. These findings suggest that SCM communities are more susceptible to environmental fluctuations than those in surface water and that future global changes (e.g., global warming) may profoundly influence the development, persistence, and service of SCM in the AO.

Importance of seasonal sea ice in the western Arctic ocean to the Arctic and global microplastic budgets

Arctic sea ice entraps microplastics (MP) from seawater and atmosphere and is recognized as sink and transport vector of MPs. However, ice-trapped fraction in the global MP budget, contribution of atmospheric input, and linkage among Arctic basins remain unclear. To assess them, we investigated the number- and mass-based data separated by size and shape geometry for MPs in sea ice, snow, and melt pond water from the western Arctic Ocean (WAO). A significant dependency of MP data on measured cutoff size and geometry was found. For the same size range and geometry, sea ice MPs in WAO ((11.4 ± 9.12) × 10³ N m^-3 for ≥ 100 µm) were within comparable levels with those in other Arctic basins, but showed closer similarity in polymer and shape compositions between WAO and Arctic Central Basin, indicating the strong linkage of the two basins by the Transpolar Drift. Our budgeting shows that a significant amount of plastic particles ((3.4 ± 2.6) × 10¹⁶ N; 280 ± 701 kilotons), which are missed from the global inventory, is trapped in WAO seasonal sea ice, with < 1% snowfall contribution. Our findings highlight that WAO ice zone may play a role as a sink of global MPs as well as a source of Arctic MPs.

Contrasting Community Composition of Active Microbial Eukaryotes in Melt Ponds and Sea Water of the Arctic Ocean Revealed by High Throughput Sequencing

Melt ponds (MPs), form as the result of thawing of snow and sea ice in the summer, have lower albedo than the sea ice and are thus partly responsible for the polar amplification of global warming. Knowing the community composition of MP organisms is key to understanding their roles in the biogeochemical cycles of nutrients and elements. However, the community composition of MP microbial eukaryotes has rarely been studied. In the present study, we assessed the microbial eukaryote biodiversity, community composition, and assembly processes in MPs and surface sea water (SW) using high throughput sequencing of 18S rRNA of size-fractionated samples. Alpha diversity estimates were lower in the MPs than SW across all size fractions. The community composition of MPs was significantly different from that of SW. The MP communities were dominated by members from Chrysophyceae, the ciliate classes Litostomatea and Spirotrichea, and the cercozoan groups Filosa-Thecofilosea. One open MP community was similar to SW communities, which was probably due to the advanced stage of development of the MP enabling the exchange of species between it and adjacent SW. High portions of shared species between MPs and SW may indicate the vigorous exchange of species between these two major types of environments in the Arctic Ocean. SW microbial eukaryote communities are mainly controlled by dispersal limitation whereas those of MP are mainly controlled by ecological drift.

Correction to: Genomic and metatranscriptomic analyses of carbon remineralization in an Antarctic polynya

Following publication of the original article [1], the authors identified wrong citations in the maintext.

Genomic and metatranscriptomic analyses of carbon remineralization in an Antarctic polynya

BACKGROUND

Polynyas in the Southern Ocean are regions of intense primary production, mainly by Phaeocystis antarctica. Carbon fixed by phytoplankton in the water column is transferred to higher trophic levels, and finally, to the deep ocean. However, in the Amundsen Sea, most of this organic carbon does not reach the sediment but is degraded in the water column due to high bacterial heterotrophic activity.

RESULTS

We reconstructed 12 key bacterial genomes from different phases of bloom and analyzed the expression of genes involved in organic carbon remineralization. A high correlation of gene expression between the peak and decline phases was observed in an individual genome bin-based pairwise comparison of gene expression. Polaribacter belonging to Bacteroidetes was found to be dominant in the peak phase, and its transcriptional activity was high (48.9% of the total mRNA reads). Two dominant Polaribacter bins had the potential to utilize major polymers in P. antarctica, chrysolaminarin and xylan, with a distinct set of glycosyl hydrolases. In the decline phase, Gammaproteobacteria (Ant4D3, SUP05, and SAR92), with the potential to utilize low molecular weight-dissolved organic matter (LMW-DOM) including compatible solutes, was increased. The versatility of Gammaproteobacteria may contribute to their abundance in organic carbon-rich polynya waters, while the SAR11 clade was found to be predominant in the sea ice-covered oligotrophic ocean. SAR92 clade showed transcriptional activity for utilization of both polysaccharides and LMW-DOM; this may account for their abundance both in the peak and decline phases. Ant4D3 clade was dominant in all phases of the polynya bloom, implicating the crucial roles of this clade in LMW-DOM remineralization in the Antarctic polynyas.

CONCLUSIONS

Genomic reconstruction and in situ gene expression analyses revealed the unique metabolic potential of dominant bacteria of the Antarctic polynya at a finer taxonomic level. The information can be used to predict temporal community succession linked to the availability of substrates derived from the P. antarctica bloom. Global warming has resulted in compositional changes in phytoplankton from P. antarctica to diatoms, and thus, repeated parallel studies in various polynyas are required to predict global warming-related changes in carbon remineralization.

Recalcitrant anal and genital pruritus treated with dupilumab

Chronic anogenital pruritus can significantly impair affected patients’ quality of life by disrupting their sleep, mood, sexual function, and personal relationships. Although a significant portion of these patients can be managed with hygiene measures, topical therapy, oral anti-pruritics, and allergen avoidance after patch testing, guidelines to treat patients who do not respond to standard therapy have yet to be established. We describe the therapeutic response of a case of anogenital pruritus recalcitrant to multiple topical and systemic therapies. Treatment of this patient with dupilumab, an interleukin-4 receptor alpha blocker, resulted in clinical remission at 1 year from the initiation of the therapy, without significant adverse effects.

Can pelagic ciliates indicate vertical variation in the water quality status of western Arctic pelagic ecosystems?

The vertical pattern of pelagic ciliate communities was observed at eight layers in the Chukchi Sea and the northern Bering Sea of the western Arctic Ocean during the summer sea-ice reduction period (August 5 to August 24, 2016). A total of 44 ciliate species were identified, with seven species dominated the communities in the water column. Multivariate and univariate analyses demonstrated that: (1) community structures of ciliates vary significantly among eight water depths; (2) variations in the vertical distribution of ciliates were significantly correlated with changes in physicochemical variables, especially the ammonia; (3) the distributions of the three dominant species were significantly and positively related to the chlorophyll a and ammonia concentrations; and (4) species richness and abundance were significantly and positively correlated with the concentrations of ammonia and chlorophyll a. These results suggest that pelagic ciliates may reflect vertical variations in the water quality status of western Arctic ecosystems.

Vertical shift in ciliate body-size spectrum and its environmental drivers in western Arctic pelagic ecosystems

As an inherent functional trait, body-size spectrum is widely used as an informative indicator to summarize community structures in taxon-free space. The vertical shift in the body-size spectrum of pelagic ciliates and its environmental drivers were explored at eight depth layers from the water surface to a depth of 100 m in western Arctic pelagic ecosystems. A total of 85 samples were collected at 23 sampling stations during the summer sea-ice reduction period from August 5 to August 24, 2016. Based on equivalent spherical diameter (ESD), six body-size ranks were identified, of which ranks S2 (15-25 μm), S3 (26-38 μm), S4 (39-60 μm), and S6 (79-91 μm) were the top four levels in frequency of occurrence and ranks S2 and S3 were the dominant levels in abundance. The body-size spectrum of the ciliates showed a clear vertical shift, with a significant succession among the dominant body-size units from the water surface to deeper layers in the water column. Multivariate analysis demonstrated a significant vertical variation in the body-size spectrum of the ciliates among the eight depths, which was significantly correlated with nutrients (phosphate and nitrite + nitrate) and chlorophyll a (Chl a), alone or in combination with dissolved oxygen. Four body-size diversity/distinctness indices were significantly correlated with the levels of phosphate, nitrite + nitrate, ammonium, and Chl a. Our results demonstrated that the body-size spectrum of pelagic ciliates can be shifted by environmental drivers (mainly nutrients and Chl a); thus, we suggest that it may be used to indicate water quality status on a vertical scale in the water column in deep seas.

Postmeal increment in intact glucagon-like peptide 1 level, but not intact glucose-dependent insulinotropic polypeptide levels, is inversely associated with metabolic syndrome in patients with type 2 diabetes

PURPOSE

Metabolic syndrome increases the risk of cardiovascular disease. Recently glucagon-like peptide 1 (GLP-1) agonists proved to be effective in preventing cardiovascular disease (CVD) in patients with type 2 diabetes. We investigated the association of blood incretin levels with metabolic syndrome in patients with type 2 diabetes.

MATERIALS AND METHODS

This is a cross-sectional study involving 334 people with type 2 diabetes. Intact GLP-1 (iGLP-1) and intact glucose-dependent insulinotropic polypeptide (iGIP) levels were measured in a fasted state and 30 min after ingestion of a standard mixed meal. Metabolic syndrome was diagnosed based on the criteria of the International Diabetes Federation.

RESULTS

Two hundred twenty-five (69%) of the subjects have metabolic syndrome. The fasting iGLP-1 level was no different between groups. Thirty-min postprandial iGLP-1 was non-significantly lower in the subjects who had metabolic syndrome. Incremental iGLP-1 (ΔiGLP-1, the difference between 30-min postmeal and fasting iGLP-1 levels) was significantly lower in those with metabolic syndrome. There were no significant differences in fasting iGIP, postprandial iGIP, and ΔiGIP between groups. The ΔiGLP-1, but not ΔiGIP levels decreased significantly as the number of metabolic syndrome components increased. In hierarchical logistic regression analysis, the ΔiGLP-1 level was found to be a significant contributor to metabolic syndrome even after adjusting for other covariates.

CONCLUSION

Taken together, the iGLP-1 increment in the 30 min after meal ingestion is inversely associated with metabolic syndrome in patients with type 2 diabetes. This suggests that postmeal iGLP-1 increment could be useful in assessing cardiovascular risk in type 2 diabetes.

Intracellular glutathione production, but not protein glycation, underlies the protective effects of captopril against 2-deoxy-D-ribose-induced β-cell damage

Our previous study reported that both oxidative stress and protein glycation were the principal mechanisms underlying 2‑deoxy‑D‑ribose (dRib)‑induced pancreatic β‑cell damage. The aim of the present study was to investigate the effects of captopril on dRib‑induced damage in pancreatic β‑cells, as well as to determine the mechanisms underlying these effects. Treatment with dRib increased the levels of cytotoxicity, apoptosis, and intracellular reactive oxygen species in Syrian hamster insulinoma HIT‑T15 cells; however, pretreatment with captopril significantly inhibited the effects of dRib. The intracellular levels of reduced and oxidized glutathione were depleted following treatment with dRib; however, these levels were restored following HIT‑T15 cell treatment with captopril. In rat islets, dRib stimulation suppressed the mRNA expression levels of insulin, and pancreatic and duodenal homeobox 1, as well as insulin content; however, these effects were dose‑dependently reversed by treatment with captopril. Treatment with buthionine sulfoximine, an inhibitor of intracellular glutathione biosynthesis, inhibited the protective effects of captopril on dRib‑mediated glutathione depletion and cytotoxicity in HIT‑T15 cells. Following incubation with albumin, dRib increased the formation of dicarbonyl and advanced glycation end products. Treatment with captopril did not inhibit the dRib‑induced increase in production of dicarbonyl and advanced glycation end products. In conclusion, treatment with captopril reversed dRib‑induced oxidative damage and suppression of insulin expression in β‑cells. The mechanism underlying the protective effects of captopril may involve increased intracellular glutathione production, rather than protein glycation.

Production rate estimation of mycosporine-like amino acids in two Arctic melt ponds by stable isotope probing with NAH(13) CO3

The net carbon uptake rate and net production rate of mycosporine-like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a (13) C stable isotope tracer technique. The Research Vessel Araon visited ice-covered western-central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.24 mg C · m(-3) · h(-1) (SD = ±1.12 mg C · m(-3) · h(-1) ), while that in the open MP was 1.3 mg C · m(-3) · h(-1) (SD = ±0.05 mg C · m(-3) · h(-1) ). The net production rate of total MAAs in incubated PC bottles was highest (1.44 (SD = ±0.24) ng C · L(-1) · h(-1) ) in the open MP and lowest (0.05 (SD = ±0.003) ng C · L(-1) · h(-1) ) in the closed MP. The net production rate of shinorine and palythine in incubated PC bottles at the open MP presented significantly high values 0.76 (SD = ±0.12) ng C · L(-1) · h(-1) and 0.53 (SD = ±0.06) ng C · L(-1) · h(-1) . Our results showed that high net production rate of MAAs in the open MP was enhanced by a combination of osmotic and UVR stress and that in situ net production rates of individual MAA can be determined using (13) C tracer in MPs in Arctic sea ice.

Jeju seaweeds suppress lipopolysaccharide-stimulated proinflammatory response in RAW 264.7 murine macrophages

OBJECTIVE

To investigate the anti-inflammatory effects of Jeju seaweeds on macrophage RAW 264.7 cells under lipopolysaccharide (LPS) stimulation.

METHODS

Ethyl acetate fractions were prepared from five different types of Jeju seaweeds, Dictyopteris divaricata (D. divaricata), Dictyopteris prolifera (D. prolifera), Prionitis cornea (P. cornea), Grateloupia lanceolata (G. lanceolata), and Grateloupia filicina (G. filicina). They were screened for inhibitory effects on proinflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6).

RESULTS

Our results revealed that D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina potently inhibited LPS-stimulated NO production (IC50 values were 18.0, 38.36, 38.43, 32.81 and 37.14 µg/mL, respectively). Consistent with these findings, D. divaricata, D. prolifera, P. cornea, and G. filicina also reduced the LPS-induced and prostaglandin E2 production in a concentration-dependent manner. Expectedly, they suppressed the expression of inducible NO synthase and cyclooxygenase-2 at the protein level in a dose-dependent manner in the RAW 264.7 cells, as determined by western blotting. In addition, the levels of TNF-α and IL-6, released into the medium, were also reduced by D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina in a dose-dependent manner (IC50 values for TNF-α were 16.11, 28.21, 84.27, 45.52 and 74.75 µg/mL, respectively; IC50 values for IL-6 were 37.35, 80.08, 103.28, 62.53 and 84.28 µg/mL, respectively). The total phlorotannin content was measured by the Folin-Ciocalteu method and expressed as phloroglucinol equivalents. The content was 92.0 µg/mg for D. divaricata, 151.8 µg/mg for D. prolifera, 57.2 µg/mg for P. cornea, 53.0 µg/mg for G. lanceolata, and 40.2 µg/mg for G. filicina.

CONCLUSIONS

Thus, these findings suggest that Jeju seaweed extracts have potential therapeutic applications for inflammatory responses.

Unveiling abundance and distribution of planktonic Bacteria and Archaea in a polynya in Amundsen Sea, Antarctica

Polynyas, areas of open water surrounded by sea ice, are sites of intense primary production and ecological hotspots in the Antarctic Ocean. This study determined the spatial variation in communities of prokaryotes in a polynya in the Amundsen Sea using 454 pyrosequencing technology, and the results were compared with biotic and abiotic environmental factors. The bacterial abundance was correlated with that of phytoplankton, Phaeocystis spp. and diatoms. A cluster analysis indicated that the bacterial communities in the surface waters of the polynya were distinct from those under the sea ice. Overall, two bacterial clades, Polaribacter (20-64%) and uncultivated Oceanospirillaceae (7-34%), dominated the surface water in the polynya while the Pelagibacter clade was abundant at all depths (7-42%). The archaeal communities were not as diverse as the bacterial communities in the polynya, and marine group I was dominant (> 80%). Canonical correspondence analysis indicated that the oceanographic properties facilitated the development of distinct prokaryotic assemblages in the polynya. This analysis of the diversity and composition of the psychrophilic prokaryotes associated with high phytoplankton production provides new insights into the roles of prokaryotes in biogeochemical cycles in high-latitude polynyas.

Sargachromenol from Sargassum micracanthum inhibits the lipopolysaccharide-induced production of inflammatory mediators in RAW 264.7 macrophages

During our ongoing screening program designed to determine the anti-inflammatory potential of natural compounds, we isolated sargachromenol from Sargassum micracanthum. In the present study, we investigated the anti-inflammatory effects of sargachromenol on lipopolysaccharide (LPS)-induced inflammation in murine RAW 264.7 macrophage cells and the underlying mechanisms. Sargachromenol significantly inhibited the LPS-induced production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in a dose-dependent manner. It also significantly inhibited the protein expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner in LPS-stimulated macrophage cells. Further analyses showed that sargachromenol decreased the cytoplasmic loss of inhibitor κBα (IκBα) protein. These results suggest that sargachromenol may exert its anti-inflammatory effects on LPS-stimulated macrophage cells by inhibiting the activation of the NF-κB signaling pathway. In conclusion, to our knowledge, this is the first study to show that sargachromenol isolated from S. micracanthum has an effective anti-inflammatory activity. Therefore, sargachromenol might be useful for cosmetic, food, or medical applications requiring anti-inflammatory properties.

Alpha-lipoic acid treatment reverses 2-deoxy-D-ribose-induced oxidative damage and suppression of insulin expression in pancreatic beta-cells

We investigated whether α-lipoic acid (LA) could prevent 2-deoxy-D-ribose (dRib)-induced oxidative damage and suppression of insulin expression in pancreatic β-cells. Stimulation with 50 mM dRib elevated cytotoxicity, apoptosis and intracellular reactive oxygen species (ROS) levels in HIT-T15 cells, but pretreatment with LA significantly reversed the dRib-induced changes. LA directly scavenged hydroxyl radicals generated by a Fenton reaction. Intracellular reduced glutathione (GSH) and oxidized glutathione (GSSG) were depleted by stimulation with dRib but levels were restored by addition of LA to HIT-T15 cells. However, the GSH/GSSG ratio was unchanged by LA treatment. In rat islets, stimulation with 10 mM dRib for 6 h suppressed expression of insulin and pancreatic and duodenal homeobox 1 mRNA and decreased insulin content, but these were dose-dependently reversed when LA was added. Treatment with l-buthionine-sulfoximine, an inhibitor of intracellular glutathione biosynthesis, completely abolished the protective effects of LA on dRib-mediated glutathione depletion and cytotoxicity in HIT-T15 cells. In summary, LA reversed the dRib-induced oxidative damage and suppression of insulin expression in β-cells. Enhanced intracellular total glutathione production, rather than the scavenging of ROS, is possibly the mechanism for the protective effect of LA.

Anti-inflammatory effects of apo-9'-fucoxanthinone from the brown alga, Sargassum muticum

Background

The marine environment is a unique source of bioactive natural products, of which Sargassum muticum (Yendo) Fensholt is an important brown algae distributed in Jeju Island, Korea. S. muticum is a traditional Korean food stuff and has pharmacological functions including anti-inflammatory effects. However, the active ingredients from S. muticum have not been characterized.

Methods

Bioguided fractionation of the ethanolic extract of S. muticum, collected from Jeju island, led to the isolation of a norisoprenoid. Its structure was determined by analysis of the spectroscopic data. In vitro anti-inflammatory activity and mechanisms of action of this compound were examined using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells through ELISA assays and Western blot analysis.

Results

Apo-9′-fucoxanthinone, belonging to the norisoprenoid family were identified. Apo-9′-fucoxanthinone effectively suppressed LPS-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production. This compound also exerted their anti-inflammatory actions by down-regulating of NF-κB activation via suppression of IκB-α in macrophages.

Conclusions

This is the first report describing effective anti-inflammatory activity for apo-9’-fucoxanthinone′-fucoxanthnone isolated from S. muticum. Apo-9′-fucoxanthinone may be a good candidate for delaying the progression of human inflammatory diseases and warrants further studies.

Sargachromanol G regulates the expression of osteoclastogenic factors in human osteoblast-like MG-63 cells

Bone diseases are characterized by the presence of pro-inflammatory cytokines that regulate bone turnover. The receptor activator of NF-κB ligand (RANKL) is a soluble osteoblast-derived protein that induces bone resorption through osteoclast differentiation and activation. Sargachromanol G (SG) was isolated from the brown algae Sargassum siliquastrum; SG has anti-osteoclastogenic activity, but its mechanism of action and its active components remain largely unknown. In the present study, we investigated the anti-osteoclastogenic effects of SG on the expression of interleukin-1β (IL-1β)-induced osteoclastogenic factors (PGE(2), COX-2, IL-6, OPG, and RANKL) in the human osteoblast cell line MG-63. We also examined the role of the nuclear factor-κB (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathways in IL-1β-stimulated MG-63 cells. SG dose-dependently inhibited the production of osteoclastogenic factors in MG-63 cells. SG also inhibited phosphorylation of MAPK (ERK1/2, p38, and JNK) and NF-κB (p65, p50, and IκB-α). These results suggest that the anti-osteoporotic effect of SG may be because of the modulation of osteoclastogenic factors via suppression of MAPK and NF-κB activation.

Resveratrol improves insulin signaling in a tissue-specific manner under insulin-resistant conditions only: in vitro and in vivo experiments in rodents

Resveratrol (RSV) has various metabolic effects, especially with relatively high-dose therapy. However, the ability of RSV to modulate insulin signaling has not been completely evaluated. Here, we determined whether RSV alters insulin signaling in insulin-responsive cells and tissues. The effects of RSV on insulin signaling in 3T3-L1 adipocytes under both insulin-sensitive and insulin-resistant states and in insulin-sensitive tissues of high fat-fed diet-induced obese (DIO) mice were investigated. Insulin-stimulated insulin receptor substrate-1 tyrosine phosphorylation (Y612) was suppressed in RSV-treated adipocytes compared with untreated adipocytes, as was the insulin-stimulated Akt phosphorylation (Ser473). However, under an insulin-resistant condition that was made by incubating 3T3-L1 adipocytes in the conditioned medium from lipopolysaccharide-stimulated LAW264.7 cells, RSV reduced inducible nitric oxide synthase expression and IκBα protein degradation and improved insulin-stimulated Akt phosphorylation (Ser473). In DIO mice, relatively low-dose RSV (30 mg/kg daily for 2 weeks) therapy lowered fasting blood glucose level and serum insulin, increased hepatic glycogen content, and ameliorated fatty liver without change in body weight. The insulin-stimulated Akt phosphorylation was decreased in the liver and white adipose tissue of DIO mice, but it was completely normalized by RSV treatment. However, in the skeletal muscle of DIO mice, insulin signaling was not improved by RSV treatment, whereas the phosphorylation of adenosine monophosphate-activated protein kinase α (Thr172) was improved by it. Our results show that RSV enhances insulin action only under insulin-resistant conditions and suggest that the effect of RSV may depend on the type of tissue being targeted and its metabolic status.

Sasa quelpaertensis phenylpropanoid derivative suppresses lipopolysaccharide-induced nitric oxide synthase and cyclo-oxygenase-2 expressions in RAW 264.7 cells

3-O-p-Coumaroyl-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-O-β-D-gulcopyranosylpropanol (ESQ10) is a naturally occurring phenylpropanoid derivative isolated from Sasa quelpaertensis (Gramineae). In the present study, we discovered that ESQ10 inhibits nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. ESQ10 attenuated LPS-induced synthesis of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in parallel and inhibited LPS-induced interleukin-6 production, as determined by an enzyme-linked immunosorbent assay in the macrophages. The mechanism of the antiinflammatory action of ESQ10, i.e., suppression of nuclear factor (NF)-κB and mitogen-activated protein kinase activation, has been documented. However, ESQ10 could not influence LPS-mediated IκB-α degradation and extracellular signal-regulated kinase/c-Jun amino-terminal kinase phosphorylation at concentrations of up to 373 µM. To test the potential application of ESQ10 as a topical material, we also conducted a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human HaCaT keratinocytes as well as human dermal fibroblast cells. In this assay, ESQ10 did not induce cytotoxicity. Taken together, the results suggest that ESQ10 may be considered an antiinflammatory candidate for treating inflammatory and skin diseases.

Purification and characterization of antifungal δ-dodecalactone from Lactobacillus plantarum AF1 isolated from kimchi

The aim of this study was to purify and identify an antifungal compound from Lactobacillus plantarum AF1, which was isolated from kimchi. The antifungal compound was purified by solid-phase extraction and recycling preparative high-performance liquid chromatography, and its structure was elucidated by using gas chromatography-mass spectrometry (GC-MS). The active compound from L. plantarum AF1 was confirmed to be δ-dodecalactone (molecular weight, 198.3) by comparison of its gas chromatographic retention time with the mass spectrum of standard δ-dodecalactone. The MICs of δ-dodecalactone against various fungi and bacteria ranged from 350 to 6,250 m g/ml. δ-Dodecalactone showed strong antifungal activity against molds Aspergillus flavus, A. fumigatus, A. petrakii, A. ochraceus, A. nidulans, and Penicillium roqueforti. The three tested yeast strains of Candida albicans were more resistant than the molds. Antibacterial activity was evident but less potent than the antifungal activity. δ-Dodecalactone produced pleasurable (fruity) organoleptic characteristics. The results indicate the potential of the δ-dodecalactone produced by L. plantarum AF1 as a biopreservative and flavoring compound, as well as a biosafe remedy for candidiasis.

Inhibitory effect of Jeju endemic seaweeds on the production of pro-inflammatory mediators in mouse macrophage cell line RAW 264.7

Seaweed has been used in traditional cosmetics and as a herbal medicine in treatments for cough, boils, goiters, stomach ailments, and urinary diseases, and for reducing the incidence of tumors, ulcers, and headaches. Despite the fact that seaweeds are frequently used in the practice of human health, little is known about the role of seaweed in the context of inflammation. This study aimed to investigate the influence of Jeju endemic seaweed on a mouse macrophage cell line (RAW 264.7) under the stimulation of lipopolysaccharide (LPS). Ethyl acetate extracts obtained from 14 different kinds of Jeju seaweeds were screened for inhibitory effects on pro-inflammatory mediators. Our results revealed that extracts from five seaweeds, Laurencia okamurae, Grateloupia elliptica, Sargassum thunbergii, Gloiopeltis furcata, and Hizikia fusiformis, were potent inhibitors of the production of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E(2) (PGE(2)), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). Based on these results, the anti-inflammatory effects and low cell toxicity of these seaweed extracts suggest potential therapeutic applications in the regulation of the inflammatory response.

Purification of a new antifungal compound produced by Lactobacillus plantarum AF1 isolated from kimchi

The aim of this study was to purify and to identify an antifungal compound of Lactobacillus plantarum AF1, which was isolated from kimchi, and to determine if Lb. plantarum AF1 can prevent fungal growth in a particular food model system. The antifungal compound was purified using SPE and recycling prep-HPLC and its structure was elucidated using NMR and ESI-MS. The active compound from Lb. plantarum AF1 is C(12)H(22)N(2)O(2), 3,6-bis(2-methylpropyl)-2,5-piperazinedion has a molecular mass of 226. This is a new antifungal compound produced by lactic acid bacteria (LAB). To investigate the potential application of the antifungal compound to eliminate fungal spoilage in food and feed, soybean was used as a model. White mycelia and dark green spores of Aspergillus flavus ATCC 22546 were observed in the control soybeans after 1 to 2days incubation. However, fungal growth was not observed in the soybeans treated with a 4-fold concentrated supernatant of Lb. plantarum AF1 culture, even after 2days. The end products produced from kimchi LAB, like 3,6-bis(2-methylpropyl)-2,5-piperazinedion identified in this study, may be a promising alternative to chemical preservatives as a potential biopreservative which prevent fungal spoilage and mycotoxin formation in food and feed.

Inhibitory effects of Fortunella japonica var. margarita and Citrus sunki essential oils on nitric oxide production and skin pathogens

A number of essential oils from citrus peels are claimed to have biological activities. Citrus peel, called 'Jin-Pi', is used in traditional medicine for digestion, severe cold, and fever. However, the antibacterial activities against skin pathogens and anti-inflammatory effects of the essential oils of Citrus sunki (JinGyul) and Fortunella japonica var. margarita (GumGyul) have not yet been described. Therefore, in this study, the essential oils of the citrus species C. sunki (CSE) and F. japonica var. margarita (FJE), both native to the island of Jeju, Korea, were examined for their anti-inflammatory and antimicrobial activities against skin pathogens. Four human skin pathogenic microorganisms, Staphylococcus epidermidis CCARM 3709, Propionibacterium acnes CCARM 0081, Malassezia furfur KCCM 12679, and Candida albicans KCCM 11282, were studied. CSE and FJE exhibited strong antimicrobial activity against most of the pathogenic bacteria and yeast strains that were tested. Interestingly, CSE and FJE even showed antimicrobial activity against antibiotic-resistant S. epidermidis CCARM 3710, S. epidermidis CCARM 3711, P. acnes CCARM9009, and P. acnes CCARM9010 strains. In addition, CSE and FJE reduced the lipopolysaccharide (LPS)-induced secretion of nitric oxide (NO) in RAW 264.7 cells, indicating that they have anti-inflammatory effects. We also analysed the chemical composition of the oils by gas chromatography-mass spectrometry (GC-MS) and identified several major components, including dl-limonene (68.18%) and beta-myrcene (4.36%) for CSE, and dl-limonene (61.58%) and carvone (6.36%) for FJE. Taken together, these findings indicate that CSE and FJE have great potential to be used in human skin health applications.

Eutigoside C inhibits the production of inflammatory mediators (NO, PGE2, IL-6) by down-regulating NF-κB and MAP kinase activity in LPS-stimulated RAW 264.7 cells

Eutigoside C, a compound isolated from the leaves of Eurya emarginata, is thought to be an active anti-inflammatory compound which operates through an unknown mechanism. In the present study we investigated the molecular mechanisms of eutigoside C activity in lipopolysacchardide (LPS)-stimulated murine macrophage RAW 264.7 cells. Treatment with eutigoside C inhibited LPS-stimulated production of nitric oxide (NO), prostaglandin E2 (PGE2) and interleukin-6 (IL-6). To further elucidate the mechanism of this inhibitory effect of eutigoside C, we studied LPS-induced nuclear factor (NF)-κB activation and mitogen-activated protein (MAP) kinase phosphorylation. Eutigoside C suppressed NF-κB DNA binding activity, interfering with nuclear translocation of NF-κB. Eutigoside C suppressed the phosphorylation of three MAP kinases (ERK1/2, JNK and p38). These results suggest that eutigoside C inhibits the production of inflammatory mediators (NO, PGE2 and interleukin-6) by suppressing the activation and translocation of NF-κB and the phosphorylation of MAP kinases (ERK1/2, JNK and p38) in LPS-stimulated murine macrophage RAW 264.7 cells.

Social experience organizes parallel networks in sensory and limbic forebrain

Successful social behavior can directly influence an individual's reproductive success. Therefore, many organisms readily modify social behavior based on past experience. The neural changes induced by social experience, however, remain to be fully elucidated. We hypothesize that social modulation of neural systems not only occurs at the level of individual nuclei, but also of functional networks, and their relationships with behavior. We used the green anole lizard (Anolis carolinensis), which displays stereotyped, visually triggered social behaviors particularly suitable for comparisons of multiple functional networks in a social context, to test whether repeated aggressive interactions modify behavior and metabolic activity in limbic-hypothalamic and sensory forebrain regions, assessed by quantitative cytochrome oxidase (a slowly accumulating endogenous metabolic marker) histochemistry. We found that aggressive interactions potentiate aggressive behavior, induce changes in activities of individual nuclei, and organize context-specific functional neural networks. Surprisingly, this experiential effect is not only present in a limbic-hypothalamic network, but also extends to a sensory forebrain network directly relevant to the behavioral expression. Our results suggest that social experience modulates organisms' social behavior via modifying sensory and limbic neural systems in parallel both at the levels of individual regions and networks, potentially biasing perceptual as well as limbic processing.

Direct action of gonadotropin in brain integrates behavioral and reproductive functions

Essential roles for gonadotropins in gonadal development and reproduction are well established. Over the past decade, however, the expression of luteinizing hormone receptor (LHR) has also been reported in the brain of various mammals and birds. Although suggestive, it has not yet been determined whether this expression pattern supports a novel function for gonadotropins. Here, we demonstrate a CNS-mediated role of gonadotropins in a reproductive behavior: the courtship songs of the South African clawed frog, Xenopus laevis. Male advertisement calling in this species depends on a nongonadal action of gonadotropin. To determine whether this effect is due to action on the CNS, we administered gonadotropin intracerebroventricularly (ICV) or systemically to intact or castrated males with or without concomitant androgen replacement. In intact and androgen-replaced gonadectomized males, gonadotropin significantly increased calling within 1 h after ICV injection. The effective dosage via ICV injections was less than one hundredth of the effective systemic dose. In situ hybridization with a cloned fragment of Xenopus LHR revealed strong expression in ventral forebrain areas important for vocal control. Further, gonadotropin treatment of brain in vitro up-regulates immunoreactivity for the LHR downstream target, egr-1, specifically in these vocal forebrain areas. Up-regulation occurs even when synaptic transmission is suppressed by incubation in Ca2+ free/high magnesium saline. These results demonstrate a neural role for gonadotropin in the control of calling behavior, potentially mediated via LHRs in forebrain vocal nuclei. Gonadotropin may play a novel integrative role in modulating both reproductive physiology and behavior.

Dominance status predicts response to nonsocial forced movement stress in the green anole lizard (Anolis carolinensis)

We used changes in body color and eyespot formation, two somatic indices of stress controlled mainly by catecholamine activity, to compare the reactions of dominant and subordinate male green anole lizards (Anolis carolinensis) to a nonsocial stressor, forced movement. Individual males were pretested by subjecting them to 10 min of forced movement induced by chasing them around their home cage with a slender wooden stick. Stress responses were assayed via changes in body color (progressive darkening from green to brown indicating increasing stress) and expression of a black postorbital eyespot (which appears with increasing catecholaminergic stress responses). Lizards were paired and allowed to form stable dominant/subordinate relationships for 2 weeks. After that period of stable social status, dominants and subordinates were separated and subjected to the same forced-movement stress. There was no difference between experimental groups in the pretest. After assuming positions in the dominance hierarchy, however, dominant males showed reduced somatic indicators of stress and were quicker to recover from the stress. The data suggest that animals that assumed the dominant position decreased their stress response relative to the pretest, while animals that assumed the subordinate position increased their stress response relative to the pretest. The results indicate that dominant social status may have advantages beyond the realm of social interactions by enhancing an individual's ability to tolerate other, nonsocial stressful events.

Interaction effects of corticosterone and experience on aggressive behavior in the green anole lizard

Aggressive encounters are accompanied by a release of stress hormone, and this corticosterone (CORT) secretion could influence aggressive behavior in subsequent encounters. We investigated the modulating effects of CORT on aggressive behavior in the context of a 5-day social experience in male green anole lizards. In Experiment 1, we measured plasma CORT levels in animals that were exposed for different times to aggressive males. In Experiment 2, using metyrapone, a CORT synthesis blocker, we tested whether CORT secretion in response to the aggressive stimulus plays a role in experience-dependent facilitation of aggressive behavior. We hypothesized that aggressive encounters would increase plasma CORT levels, and that blocking CORT synthesis with metyrapone treatment during the aggressive encounter would cause an animal to become more aggressive. We also tested whether blocking CORT would interfere with the influence of 5-day social experience on animals' behavior in a subsequent aggressive encounter. Animals that were exposed to another male showed higher plasma CORT levels immediately after the 10 min encounter than animals exposed to the non-social video, and this high level was maintained through day 5. Within the aggressive video groups, in Experiment 2, there was a distinctly different pattern in displays depending on drug condition: vehicle-injected animals showed gradual increases followed by decreases in aggressive behavioral responses to the video as the five days proceeded (habituation), while animals injected with metyrapone started out with high aggressive behavior and did not decrease behavioral responses at later trials (no habituation). Finally, when tested with a novel conspecific on day 6, animals previously injected with metyrapone showed no higher aggression than did animals previously injected with vehicle and exposed to the aggressive video. These results suggest that blocking CORT synthesis during the exposure to the aggressive video induced animals to remain aggressive toward the repetitive stimulus without habituating, while not becoming more aggressive than controls toward a novel challenger.

Sex differences and hormone influences on tyrosine hydroxylase immunoreactive cells in the leopard frog

We examined sex differences in tyrosine hydroxylase immunoreactive (TH-ir) cell populations in the preoptic area (POA), suprachiasmatic nucleus (SCN), posterior tuberculum (TP), and caudal hypothalamus (Hy) in the leopard frog (Rana pipiens), in addition to the effects of natural variation in sex steroid hormones on these same populations in both sexes. All four of these populations have been shown to be dopaminergic. Gonadal sex, androgens, and estrogen all influenced TH-ir cell numbers, but in a complicated pattern of interactions. After factoring out the effects of sex steroids by multiple regression, TH-ir cell numbers in all four areas differed between the sexes, with males having a greater number of TH-ir cells. The influence of androgens and estrogen differed by region and sex of the animals. Androgens were the main influence on TH-ir cell numbers in the POA and SCN. Plasma androgen concentrations were positively correlated with TH-ir cell numbers in both areas in males. In females, androgen concentration was negatively correlated with TH-ir cell numbers in the POA; there was no significant relationship in the SCN in females. In the more caudal populations, estrogen (E2) levels were positively correlated with TH-ir cell numbers in the TP of both males and females. In the caudal hypothalamus, E2 levels were positively correlated with TH-ir cell numbers in females, but there was no significant correlation in males. The results indicate that gonadal sex imposes a baseline sex difference in the four TH-ir (dopamine) populations, resulting in a higher number of such cells in males. Individual and sex-linked differences in gonadal steroid hormones lead to variation around this baseline condition, with androgens having a greater influence on rostral populations and estrogen on caudal populations. Last, an individual's gonadal sex determines the effect that androgens and estrogen have on each population.

Relationships between hormones and aggressive behavior in green anole lizards: an analysis using structural equation modeling

We investigated the relationship between aggressive behavior and circulating androgens in the context of agonistic social interaction and examined the effect of this interaction on the androgen-aggression relationship in response to a subsequent social challenge in male Anolis carolinensis lizards. Individuals comprising an aggressive encounter group were exposed to an aggressive conspecific male for 10 min per day during a 5-day encounter period, while controls were exposed to a neutral stimulus for the same period. On the sixth day, their responses to an intruder test were observed. At intervals, individuals were sacrificed to monitor plasma androgen levels. Structural equation modeling (SEM) was used to test three a priori interaction models of the relationship between social stimulus, aggressive behavior, and androgen. Model 1 posits that exposure to a social stimulus influences androgen and aggressive behavior independently. In Model 2, a social stimulus triggers aggressive behavior, which in turn increases circulating levels of androgen. In Model 3, exposure to a social stimulus influences circulating androgen levels, which in turn triggers aggressive behavior. During the 5 days of the encounter period, circulating testosterone (T) levels of the aggressive encounter group followed the same pattern as their aggressive behavioral responses, while the control group did not show significant changes in their aggressive behavior or T level. Our SEM results supported Model 2. A means analysis showed that during the intruder test, animals with 5 days of aggressive encounters showed more aggressive responses than did control animals, while their circulating androgen levels did not differ. This further supports Model 2, suggesting that an animal's own aggressive behavior may trigger increases in levels of plasma androgen.

Protein kinase Dyrk1 activates cAMP response element-binding protein during neuronal differentiation in hippocampal progenitor cells

Dyrk is a dual specific protein kinase thought to be involved in normal embryo neurogenesis and brain development. Defects/imperfections in this kinase have been suggested to play an important role in the mental retardation of patients with Down's syndrome. The transcriptional factor cAMP response element-binding protein (CREB) has been implicated in the formation of many types of synaptic plasticity, such as learning and memory. In the present study we show that Dyrk1 activity is markedly induced during the differentiation of immortalized hippocampal progenitor (H19-7) cells. The addition of a neurogenic factor, basic fibroblast growth factor, to the H19-7 cells results in an increased specific binding of Dyrk1 to active CREB. In addition, Dyrk1 directly phosphorylates CREB, leading to the stimulation of subsequent CRE-mediated gene transcription during the neuronal differentiation in H19-7 cells. Blockade of Dyrk1 activation significantly inhibits the neurite outgrowth as well as CREB phosphorylation induced by basic fibroblast growth factor. These findings suggest that Dyrk1 activation and subsequent CREB phosphorylation is important in the neuronal differentiation of central nervous system hippocampal cells.

Expression and detection of ScFvB9 and its mutant in recombinant phage antibody system

Recombinant single-chain antibody (ScFvB9) and its mutant (ScFvB9-6) were generated by using a polymerase chain reaction (PCR) from the Fab fragment of the murine monoclonal antibody (MAb) B9, MabB9 (gamma2b,kappa), which is specific for human plasma apolipoprotein (apo) B-100 of low density lipopreotein (LDL). In the recombinant phage antibody system (RPAS), the constructed ScFvB9 and ScFvB9-6 antibody genes were cloned into the pCANTAB5E phagemid vector and expressed in E. coli. The active forms of single-chain antibodies (ScFvB9 and ScFvB9-6) were produced as phage-displayed recombinant antibodies or soluble antibody forms in E. coli. The activities of ScFvB9 and ScFvB9-6 were confirmed by enzyme-linked immunosorbent assay (ELISA) and Western blotting analysis; the generated mutant ScFvB9-6 showed slightly higher antigen binding activity than native ScFvB9 as a soluble antibody in this RPAS.

Suppressive effects of Adenophora triphylla extracts on in vitro tumor cell growth and in vivo gastric epithelial proliferation

Adenophora triphylla (AT), an oriental medicinal plant, was extracted using water and several organic solvents and each fraction was assayed for its tumoricidal effects on human Jurkat T cells with 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT). The influence on induction of apoptosis and G1 arrest was also examined. The ethyl acetate fraction showed the most pronounced inhibitory effects on proliferation of Jurkat T cells. Apoptosis was induced in line with up-regulation of FasL, tyrosine phosphorylation and c-fos mRNA levels. Arrest in G1 of the cell cycle was observed in A2780 cells with a wild type p53 gene but not HT-29 cells with a mutant p53 gene. Modifying effects of AT on cell turnover and glutathione(GSH) levels in vivo were also investigated in the stomach of rats given 150 mg/kg of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) by gavage and then fed a diet supplemented with 5% or 1% pulverized AT and 0.5% or 0.2% ethylacetate-extracted AT for 42 hours. The 5% AT and both of the ethylacetate fractions caused significant reduction in proliferating cell nuclear antigen (PCNA)-labeling in the glandular stomach epithelium as compared with the value for the MNNG alone group. In addition, the treatments significantly increased the gastric GSH levels. These results suggest that AT could be a chemopreventive agent against gastric cancer.

Alpha1-adrenoceptors involvement in painful diabetic neuropathy: a role in allodynia

To investigate whether alpha1-adrenoceptors are involved in pain behaviors in streptozotocin (STZ)-induced diabetic rats, we measured the effects of phenylephrine or prazosin on allodynia in the diabetic rats. Phenylephrine aggravated allodynia, while prazosin alleviated allodynia in the diabetic rats. We also measured alpha1-adrenoceptors gene expression or density of [3H]-prazosin binding sites in the dorsal root ganglia (DRG) and spinal cord in painful diabetic rats. Alpha1-adrenoceptors mRNA and density of [3H]prazosin binding sites were increased in the DRG of the diabetic rats, however there were no significant differences in alpha1-adrenoceptors expression in the spinal cord between the control and diabetic rats. These results suggest increased alpha1-adrenoceptors in the DRG may play a role in the pathogenesis of painful diabetic neuropathy.