Baicalin reduced injury of and autophagy-related gene expression in RAW264.7 cells infected with H6N6 avian influenza virus.

In the present study, we investigated whether baicalin could reduce the damage caused to RAW264.7 cells following infection with H6N6 avian influenza virus. In addition, we studied the expression of autophagy-related genes. The morphological changes in cells were observed by hematoxylin and eosin (H&E) staining, and the inflammatory factors in the cell supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was used to detect the levels of RAW264.7 autophagosomes, and western blotting and immunofluorescence were used to detect the protein expression of autophagy marker LC3. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the mRNA transcription levels of autophagy key factors. The results showed that different doses of baicalin significantly reduced the H6N6 virus-induced damage of RAW264.7 cells. The contents of interleukin (IL)-1ß, IL-2, IL-6, and tumor necrosis factor (TNF)-α in the cell supernatant significantly decreased. In addition, the protein expression of LC3 and Beclin-1, ATG12, ATG5 the mRNA levels were significantly decreased. This study showed that baicalin can reduce cell damage and affect the H6N6-induced autophagy level of RAW264.7 cells.

Antibacterial activity and mechanism of luteolin isolated from Lophatherum gracile Brongn. against multidrug-resistant Escherichia coli.

Infections caused by multidrug-resistant (MDR) bacteria have become a major challenge for global healthcare systems. The search for antibacterial compounds from plants has received increasing attention in the fight against MDR bacteria. As a medicinal and edible plant, Lophatherum gracile Brongn. (L. gracile) has favorable antibacterial effect. However, the main antibacterial active compound and its antimicrobial mechanism are not clear. Here, our study first identified the key active compound from L. gracile as luteolin. Meanwhile, the antibacterial effect of luteolin was detected by using the broth microdilution method and time-kill curve analysis. Luteolin can also cause morphological structure degeneration and content leakage, cell wall/membrane damage, ATP synthesis reduction, and downregulation of mRNA expression levels of sulfonamide and quinolones resistance genes in multidrug-resistant Escherichia coli (MDR E. coli). Furthermore, untargeted UPLC/Q-TOF-MS-based metabolomics analysis of the bacterial metabolites revealed that luteolin significantly changed riboflavin energy metabolism, bacterial chemotaxis cell process and glycerophospholipid metabolism of MDR E. coli. This study suggests that luteolin could be a potential new food additive or preservative for controlling MDR E. coli infection and spread.

Untargeted metabolomics of the intestinal tract of DEV-infected ducks.

INTRODUCTION: Duck enteritis virus (DEV) mainly causes infectious diseases characterized by intestinal haemorrhage, inflammation and parenchymal organ degeneration in ducks and other poultry. However, the mechanism by which it causes intestinal damage in ducks is not well understood. Metabolomics can provide an in-depth understanding of the full complexity of the disease. METHODS: In this study, 24 clinically healthy green-shell ducks (weight 1.5 kg ± 20 g) were randomly divided into 2 groups (experimental group, 18; control group, 6). The experimental group was intramuscularly injected with 0.2 mL of DEV virus in solution (TCID50 3.16 × 108 PFU/mL), and the control group was injected with 0.2 mL of sterile normal saline. Duck duodenum and ileum tissue samples were collected at 66 h, 90 h and 114 h post-injection (12 h of fasting before killing), and metabolomics analysis of duck duodenum and ileum tissues at the three time points (66, 90, 114 h) was performed by liquid chromatography-mass spectrometry (LC-MS) to screen for and analyse the potential differentiated metabolites and related signalling pathways. RESULTS: Screening was performed in the positive/negative mode (Pos: Positive ion mode; the ionization of substances at the ion source with positive ions such as H+, NH4+, Na+ and K+; Neg: Negative ion mode; the ionization of substances at the ion source with negative ions such as Cl-, OAc-), and compound abundance was compared to that in the control group. The total number of differentially abundant compounds in the duodenum at 66 h, 90 h and 114 h of DEV infection gradually increased, and metabolites such as cytidine, 2'-deoxyriboside and 4-guanidinobutyric acid were differentially abundant metabolites common to all three time periods. The metabolic pathways related to inflammatory response and immune response were tryptophan acid metabolism, cysteine-methionine metabolism, histidine metabolism and other amino acid metabolism and fat metabolism. Among them, the metabolic pathways with more differentially abundant metabolites were amino acid biosynthesis, cysteine and methionine metabolism, tryptophan metabolism, unsaturated fatty acid biosynthesis and purine metabolism, and the metabolic pathways with more enrichment factors were the IgA-related intestinal immune network pathway and lysosome pathway. Compared with the control group, there were 16 differentially abundant metabolites in the ileum tissue of DEV-infected ducks at 66 h of infection, 52 at 90 h of infection, and 40 at 14 h of infection with TD114. The metabolic pathways with more enriched differentially abundant metabolites were pyrimidine metabolism, tyrosine metabolism, phenylalanine metabolism and tryptophan biosynthesis. The metabolic pathways with the most enrichment factors were the mTOR signalling pathway, ferroptosis pathway, tryptophan metabolism pathway and caffeine metabolism pathway. CONCLUSION: Comparative analysis showed that the number of differentially abundant metabolites in the duodenum and ileum differed to some extent after DEV infection, with significantly more differentially abundant metabolites in duodenal tissues and fewer in ileal tissues; after DEV infection, the highest number of differentially abundant metabolites was obtained at 114 h of DEV infection, followed by the second highest at 90 h of infection and the lowest at 66 h of infection. The common differentially abundant metabolites in duodenal and ileal tissues were prostaglandins, arachidonic acid, and arachidonic ethanolamine. The main metabolic pathways in the duodenum were the IgA-associated intestinal immune network pathway and the lysosomal pathway, and the metabolic pathways with more enriched factors in the ileum were the mTOR signalling pathway, the ferroptosis pathway, and the tryptophan metabolism pathway.

Optimization of ultrasound-assisted extraction based on response surface methodology using HPLC-DAD for the analysis of red clover (Trifolium pretense L.) isoflavones and its anti-inflammatory activities on LPS-induced 3D4/2 cell.

Introduction: Trifolium pratense L. has anti-inflammatory, antioxidant, cardiovascular disease prevention, and estrogen-like effects. The existing method for the assay of effective components is commonly based on a spectrophotometer, which could not meet the requirement of quality control. Furthermore, although there have been many studies on the anti-inflammation effect of red clover, a few have been reported on the regulatory effect of red clover isoflavones (RCI) on lipopolysaccharide (LPS)-induced inflammatory response in porcine alveolar macrophages (3D4/2 cells), and its mechanism of action is still unclear. Methods: The main components of RCI including daidzein, genistein, and biochanin A were accurately quantified by high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) after optimizing the extraction process through response surface methodology. The anti-inflammatory potential of RCI was carried out by detecting the level of inflammatory cytokines and mRNA expression of related genes. Furthermore, its anti-inflammatory mechanism was explored by investigating two signaling pathways (NF-κB and MAPK). Results: The optimal extraction conditions of RCI were as follows: the concentration of ethanol is 86% and the solid-liquid ratio is 1:29, with the herb particle size of 40 mesh sieve. Under the optimal conditions, the total extraction of target components of RCI was 2,641.469 µg/g. The RCI could significantly suppress the production and expression of many pro-inflammatory cytokines. The results of the Western blot revealed that RCI dramatically reduced the expression of p65, p-p65, IκB-α, p38, and p-p38. These results are associated with the suppression of the signal pathway of p38 MAPK, and on the contrary, activating the NF-κB pathway. Collectively, our data demonstrated that RCI reversed the transcription of inflammatory factors and inhibited the expression of p65, p-p65, IκB-α, and p38, indicating that RCI had excellent anti-inflammatory properties through disturbing the activation of p38 MAPK and NF-κB pathways. Conclusion: The extraction conditions of RCI were optimized by HPLC-DAD combined with response surface methodology, which will contribute to the quality control of RCI. RCI had anti-inflammatory effects on the LPS-induced 3D4/2 cells. Its mechanism is to control the activation of NF-κB and p38 MAPK pathways, thereby reducing the expression of inflammatory-related genes and suppressing the release of cytokines.

Analysis of authorized coccidiostats in chicken feces and environmental water by ultra-performance liquid chromatography-tandem mass spectrometry based on dispersive solid-phase extraction and lyophilization.

A simple, sensitive, and efficient method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of 8 coccidiostats in chicken feces and environmental water (including sewage, pond water, and lake water) surrounding the farm. Target analytes in chicken feces were extracted with 2% acetic acid in acetonitrile solution, followed by a dispersive solid-phase extraction (DSPE) cleanup step using the mixture of PSA and C18 adsorbents. Environmental water samples were pretreated using a lyophilization approach. Analysis was carried out on a UPLC-MS/MS with the combination of methanol and 0.1% formic acid aqueous solution as the mobile phase under multiple reaction monitoring in positive and negative ionization modes. Results showed that 8 coccidiostats were linear with correlation coefficients higher than 0.99. Method validation was performed using fortified samples, reaching satisfactory recoveries of 75.9%-97.8% in chicken feces and 71.9%-108.2% in environmental water. Limits of detection for 8 analytes in chicken feces and environmental water were 0.03∼2 µg/kg and 0.005∼1 µg/L, respectively. Matrix effects were calculated and strong signal suppression (>50%) for some coccidiostats was observed. The developed method was successfully applied to analyze coccidiostats in chicken feces and environmental water collected from local chicken farms.

Molecular mechanism of anti-inflammatory effects of the proteasome inhibitor MG-132 on Con A-induced acute liver injury in mice.

MG-132, an aldehyde-based peptide proteasome inhibitor (PI) that binds to the proteasome and reversibly inhibits proteasome activity, has been widely used in experimental research. However, it is not clear whether MG-132 has anti-inflammatory effects on liver injury. The molecular mechanism of the anti-inflammatory effect of the PI MG-132 on Con A-induced acute liver injury (ALI) mice was investigated by ELISA, HE, q RT-PCR, and IHC. The results showed that the serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and TNF-α and IL-6 contents of mice in the high and medium dose groups were reduced compared with those in the ALI group. The superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in liver tissues were significantly increased, and the malondialdehyde (MDA) content was decreased. The pathological sections of mice in the ALI group showed typical ALI manifestations such as significant central venous stasis of liver tissues, cell swelling, and inflammatory cell infiltration. The pathological damage of liver tissues was relieved significantly in the three dose groups, especially in the high-dose group. The transcriptional level of TLR4/NF-κB pathway key factors mRNA was significantly reduced, and the expression of TLR4 and NF-κB P65 protein in liver tissues was significantly and positively correlated with the contents of TNF-α and IL-1ß (p < 0.01). Our findings suggest that MG-132 can alleviate the inflammatory response to Con A-induced ALI and exert a hepatoprotective effect, and its anti-inflammatory effect is related to the inhibition of TLR4/NF-κB signaling pathway activation.

Therapeutic potential of kaempferol on Streptococcus pneumoniae infection.

Co-infections with pathogens and secondary bacterial infections play significant roles during the pandemic coronavirus disease 2019 (COVID-19) pathogenetic process, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Notably, co-infections with Streptococcus pneumoniae (S. pneumoniae), as a major Gram-positive pathogen causing pneumonia or meningitis, severely threaten the diagnosis, therapy, and prognosis of COVID-19 worldwide. Accumulating evidences have emerged indicating that S. pneumoniae evolves multiple virulence factors, including pneumolysin (PLY) and sortase A (SrtA), which have been extensively explored as alternative anti-infection targets. In our study, natural flavonoid kaempferol was identified as a potential candidate drug for infection therapeutics via anti-virulence mechanisms. We found that kaempferol could interfere with the pore-forming activity of PLY by engaging with catalytic active sites and consequently inhibit PLY-mediated cytotoxicity. Additionally, exposed to kaempferol significantly reduced the SrtA peptidase activity by occupying the active sites of SrtA. Further, the biofilms formation and bacterial adhesion to the host cells could be significantly thwarted by kaempferol incubation. In vivo infection model by S. pneumoniae highlighted that kaempferol oral administration exhibited notable treatment benefits, as evidenced by decreased bacterial burden, suggesting that kaempferol has tremendous potential to attenuate S. pneumoniae pathogenicity. Scientifically, our study implies that kaempferol is a promising therapeutic option by targeting bacterial virulence factors.

Response Surface Optimization of Dispersive Solid-Phase Extraction Combined with HPLC for the Rapid Analysis of Multiple Coccidiostats in Feed.

Since antimicrobials were banned as feed additives, coccidiostats with favorable anticoccidial action and growth promotion have been widely used in the breeding industry. The monitoring of coccidiostats in feed is necessary, while the current methods based on mass-spectrometer analysis have limited applicability and matrix effects could interfere with the results. Accordingly, in the present paper, a rapid analytical strategy for the simultaneous determination of six synthetic coccidiostats in feed using high-performance liquid chromatography coupled with diode-array detection was developed. Coccidiostats in chicken feeds were extracted with the trichloroacetic acid-acetonitrile solution. The cleanup was performed by dispersive solid-phase extraction after the optimization of the response surface methodology. The method exhibited good linearity for target coccidiostats within the range of 0.05~20 µg/mL. Recoveries for six compounds in fortified feed samples were from 67.2% to 107.2% with relative standard deviations less than 9.6%. The limit of detection was 0.2~0.3 mg/kg. The successful application of the method in commercial feed verified that it is effective and sensitive for the rapid determination of multiple coccidiostats in chicken feeds.

The pharmacokinetic and residue depletion study of eugenol in carp (Cyprinus carpio).

Introduction: The pharmacokinetic profile and residue depletion of eugenol in carp (Cyprinus carpio) tissues and plasma were performed by a convenient and reliable high-performance liquid chromatography (HPLC) method. Methods: The eugenol in carp tissues and plasma was extracted with a mixed solution of acetonitrile and methanol. N-hexane was used to remove lipid impurities. The method was successfully applied to the pharmacokinetic and residue elimination of eugenol in carp after the carp was administered a medicated bath. Results: The average recoveries of eugenol in tissues and plasma fortified with four concentration levels were 69.0-106.6% and 80.0-86.7%, respectively. The relative standard deviations were < 8.9%. The limit of detection (LOD) was 0.01 µg/g in tissue and 0.008 µg/ml in plasma, respectively. The pharmacokinetic parameter of Cmax for eugenol in plasma at the concentrations of 20, 35, and 75 mg/L were 10.86, 17.21, and 37.32 mg/L, respectively. The t1/2 values were 3.68, 4.22, and 9.31 h. After the investigation of the anesthetic effect, 35 mg/L of eugenol was the optimal concentration for anesthesia. The highest accumulation concentration of eugenol in carp is in the liver and the lowest is in the muscle. In addition, the eugenol in tissue was eliminated rapidly and at a lower level than the LOD at 48 h. According to the residue elimination, the withdrawal time of eugenol was suggested at 5.2 days. Discussion: These results indicate that the developed method had good linearity and accuracy, and is sensitive enough for the monitoring of eugenol residue in carp. The half-life of eugenol decreased with the increase in drug concentration and the eugenol was eliminated rapidly in carp tissues. 35 mg/L eugenol was recommended as an anesthetic in carp due to its favorable anesthetic effect and no mortality. This study will contribute to the establishment of MRL regulation and setting a withdrawal period.

[Tryptase of mast cells in immune organs of developing chicken embryos].

OBJECTIVE: To observe the form, distribution and emerging time of the mast cells (MCs) and tryptase positive cells (TPCs) in the immune organs of different days old chicken embryos. METHODS: The thymus, bursa of Fabricius and spleen of chicken embryos at different development time were taken and fixed in Carnoy's solution. The alcian blue/safranine O (AB/SO) and streptavidin-biotin complex (SABC) immunohistochemistry were used to observe the MCs and TPCs. RESULTS: MCs were first present in the thymus, bursa and spleen of day 13-14 embryos. The number of MCs increased along with the development days. On day 16, TPCs were first found in the immune organs. The form and distribution of TPCs were similar to MCs, but the emerging time of TPCs was later than that of MCs. CONCLUSION: Tryptase appears in the MCs in the immune organs of day 16 or later chicken embryos, and it is mainly located in the MCs of the connective tissues.

Proteomic analysis reveals altered expression of proteins related to glutathione metabolism and apoptosis in the small intestine of zinc oxide-supplemented piglets.

Zinc is an important dietary factor that regulates intestinal amino acid and protein metabolism in animals. Recent work with the piglet, an established animal model for studying human infant nutrition, has shown that supplementing high levels of zinc oxide (ZnO) to the diet ameliorates weaning-associated intestinal injury and growth retardation. However, the underlying mechanisms are largely unknown. This study tested the hypothesis that zinc supplementation affects expression of proteins related to glutathione metabolism and oxidative stress in the gut. Using two-dimensional gel electrophoresis and mass spectrometry, we identified 22 up-regulated and 19 down-regulated protein spots in the jejunum of weanling piglets supplemented with ZnO (3,000 mg/kg Zn) compared with the control pigs (100 mg/kg Zn). These proteins are related to energy metabolism (increased level for succinyl-CoA transferase and decreased level for creatine kinase M-type); oxidative stress (decreased levels for 78 kDa glucose-regulated protein and glutathione-S-transferase-omega); and cell proliferation and apoptosis (increased levels for A-Raf-1 and calregulin). Consistent with the changes in protein expression, the ratio of reduced glutathione to oxidized glutathione was increased, whereas glutathione-S-transferase and glutathione peroxidase activities as well as the protein level of active caspase-3 were reduced in ZnO-supplemented piglets. Collectively, these results indicate that ZnO supplementation improves the redox state and prevents apoptosis in the jejunum of weaning piglets, thereby alleviating weaning-associated intestinal dysfunction and malabsorption of nutrients (including amino acids).

Dietary arginine supplementation affects microvascular development in the small intestine of early-weaned pigs.

This study was conducted to evaluate the effects of dietary arginine levels on microvascular development of the small intestine in early-weaned pigs. Twenty-four crossbred pigs (5.0 +/- 0.3 kg body weight) were individually housed and randomly allotted to 1 of 3 diets supplemented with 0, 0.7, and 1.2% L-arginine (8 pigs per group). Pigs consumed the diets ad libitum for 10 d. We collected blood samples on d 3, 6, and 10. On d 10, 6 pigs from each group were randomly selected and killed for tissue sample collection. Compared with control pigs, dietary supplementation with 0.7% L-arginine increased (P < 0.05) jejunal concentrations of nitrite and nitrate (stable oxidation products of nitric oxide), intestinal villus height, as well as plasma proline and arginine concentrations on d 6 and 10. Dietary supplementation with 0.7% L-arginine also increased (P < 0.05) immunoreactive expression of CD34 in duodenal submucosa, ileal mucosa and submucosa, and expression of vascular endothelial growth factor (VEGF) in duodenal submucosa, jejunal mucosa and submucosa, and ileal mucosa compared with the control and 1.2% L-arginine supplementation. Dietary supplementation with 1.2% L-arginine increased (P < 0.05) the concentration of jejunal endothelin-1 compared with the control pigs. Immunoexpression of VEGF in duodenal mucosa and plasma lysine concentrations on d 6 and 10 were lower (P < 0.05) in pigs supplemented with 1.2% L-arginine than in unsupplemented pigs. Collectively, these findings indicate that the effects of L-arginine on microvascular development are beneficial at lower levels but have adverse effects at higher intakes. Dietary supplementation with 0.7% L-arginine may be a useful method to improve microvascular development in the small intestine of early-weaned pigs.

Recombinant soybean protein beta-conglycinin alpha'-subunit expression and induced hypersensitivity reaction in rats.

BACKGROUND: The major storage protein in soybean seed is beta-conglycinin and this protein has been identified as being responsible for food-allergic reactions in several species. However, the mechanism through which beta-conglycinin induces an allergic reaction has not yet been elucidated. In addition, assessing the antigenic activity of beta-conglycinin by studying the activity of a subunit has rarely been conducted. Therefore, the objective of the present study was to characterize the antigenic specificity of the beta-conglycinin alpha'-subunit. METHODS: We established an Escherichia coli expression system to obtain beta-conglycinin alpha'-subunit. The fusion proteins were then used in a rat model to induce a hypersensitive reaction. Immunoblotting, IgE and IgG1 level, histamine release, and passive cutaneous anaphylaxis reactions and intestinal histology were tested to assess the allergenic activity of the beta-conglycinin alpha'-subunit. RESULTS: Pure beta-conglycinin alpha'-subunit was obtained by expression in E. coli. The recombinant proteins were shown to have the same biological activity as the natural beta-conglycinin alpha'-subunit using immunoblotting analysis. Both the IgE and IgG1 level in serum and the histamine concentration in the intestine were increased while passive cutaneous anaphylactic reactions were induced in Brown Norway rats by intragastric gavage with the alpha'-subunit. Histamine release of mast cells was also elevated in vitro. CONCLUSIONS: Our results indicate that the beta-conglycinin alpha'-subunit possesses an intrinsic immune-stimulating capacity and that it can induce an allergic reaction. Moreover, this study showed that beta-conglycinin alpha'-subunit-induced anaphylaxis is IgE mediated, and mast cell degranulation and histamine release are associated with anaphylactic symptoms.

Characterization of the antigenic specificity of soybean protein beta-conglycinin and its effects on growth and immune function in rats.

The objective of the present study was to characterize the antigenic specificity of purified soybean beta-conglycinin and to investigate its effects on the growth and immune responses of rats. Thirty-two Brown Norway rats, 3 weeks of age, were randomly allotted to one of four treatments and individually fed casein-cornstarch based diets. Rats were sensitised by means of intragastric gavage with purified beta-conglycinin (0, 5, 10 or 20 mg protein/ml in phosphate buffered saline at pH 7.4) on day 0, 7, 14, and 21 (1 ml/animal). On day 28, rats received a double dose of beta-conglycinin. Blood was obtained at weekly intervals after initiation of challenge. Growth declined linearly with increasing the concentration of soybean beta-conglycinin (p < 0.05). Both the total IgE and beta-conglycinin-specific IgE levels in serum increased while passive cutaneous anaphylactic reactions were induced in the rats. Lymphocyte proliferation response to concanavalin A in plasma and spleen was increased linearly with increased levels of soybean (p < 0.01) beta-conglycinin. The percentage of CD4+ lymphocyte subset linearly increased (p < 0.001). As a result, the concentrations of cytokines in plasma and spleen, including interleukin-4 (p < 0.01), interleukin-5 (p < 0.01), and tumour necrosis factor-alpha (p < 0.01) increased linearly with increasing level of purified beta-conglycinin. Our results indicate that purified beta-conglycinin possesses intrinsic immune-stimulating capacity and can induce an allergic reaction. Therefore, dietary soybean beta-conglycinin has negative effects on growth and both cell-mediated and humoral immune function in rats.

Dietary supplementation with zinc oxide decreases expression of the stem cell factor in the small intestine of weanling pigs.

Dietary supplementation with a high level of zinc oxide (ZnO) has been shown to reduce the incidence of diarrhea in weanling pigs, but the underlying mechanisms remain largely unknown. Intestinal-mucosal mast cells, whose maturation and proliferation is under the control of the stem cell factor (SCF), play an important role in the etiology of diarrhea by releasing histamine. The present study was conducted to test the novel hypothesis that supplementing ZnO to the diet for weanling piglets may inhibit SCF expression in the small intestine, thereby reducing the number of mast cells, histamine release, and diarrhea. In Experiment 1, 32 piglets (28 days of age) were weaned and fed diets containing 100 or 3000 mg zinc/kg (as ZnO) for 10 days (16 piglets per group). In Experiment 2, two groups of 28-day-old piglets (8 piglets per group) were fed the 100- or 3000-mg zinc/kg diet as in Experiment 1, except that they were pair-fed the same amounts of feed. Supplementation with a high level of ZnO reduced the incidence of diarrhea in weanling piglets. Dietary Zn supplementation reduced expression of the SCF gene at both mRNA and protein levels, the number of mast cells in the mucosa and submucosa of the small intestine and histamine release from mucosal mast cells. Collectively, our results indicate that dietary supplementation with ZnO inhibits SCF expression in the small intestine, leading to reductions in the number of mast cells and histamine release. These findings may have important implications for the prevention of weaning-associated diarrhea in piglets.

Calcium antagonist verapamil prevented pulmonary arterial hypertension in broilers with ascites by arresting pulmonary vascular remodeling.

Calcium signaling has been reported to be involved in the pathogenesis of hypertension. Verapamil, one of the calcium antagonists, is used to characterize the role of calcium signaling in the development of pulmonary arterial hypertension syndrome in broilers. The suppression effect of verapamil on pulmonary arterial hypertension and pulmonary vascular remodeling was examined in broilers, from the age of 16 days to 43 days. Our results showed that oral administration of lower dose of verapamil (5 mg/kg body weight every 12 h) prevented the mean pulmonary arterial pressure, the ascites heart index and the erythrocyte packed cell volume of birds at low temperature from increasing, the heart rate from decreasing, and pulmonary arteriole median from thickening, and no pulmonary arteriole remodeling in broilers treated with the two doses of verapamil at low temperature was observed. Our results indicated that calcium signaling was involved in the development of broilers' pulmonary arterial hypertension, which leads to the development of ascites, and we suggest that verapamil may be used as a preventive agent to reduce the occurrence and development of pulmonary arterial hypertension in broilers.

Endothelin-1 receptor antagonist BQ123 prevents pulmonary artery hypertension induced by low ambient temperature in broilers.

Evidence has indicated that endothelin-1 is related to the pathogenesis of hypertension. To characterize the role of endothelin-1 (ET-1) in the development of pulmonary hypertension syndrome in broilers, the blockade effect of ETA receptor (ET(A)) antagonist, BQ123, on blood pressure in experimental models of pulmonary hypertension was examined. Birds were locally anesthetized and instrumented with venous catheters for pulmonary arterial pressure (PAP) and right ventricular pressure (RVP), followed by packed cell volume (PCV) and Ascites heart index (AHI) measured, after exposed to low ambient temperature for 7 or 14 d. In treated groups, BQ123 (0.4 or 2.0 microg each time, 2 times a day), administered in abdominal cavities for 7 or 14 d during birds kept in low ambient temperature, prevented both PAP and RVP increasing, especially the high dose BQ123 lowered PAP and RVP to normotensive levels as that in control under normal temperature, whereas significant increases (p<0.05) were found in the two parameters of broilers in both untreated and saline treated group under low ambient temperature compared with those of birds in control. Furthermore, there was also a reduction in low ambient temperature-induced right ventricular hypertrophy in the groups administered BQ123. The preventive effect of BQ123 suggests that ET-1 is associated with the development of broilers' pulmonary hypertension, which leads to the development of ascites, and BQ123 can prevent the occurrence of pulmonary hypertension.