Decreased tryptophan hydroxylase 2 mRNA and protein expression, decreased brain serotonin concentrations, and anxiety-like behavioral changes in a rat model of simulated transport stress.

Transport stress causes not only physiological changes but also behavioral responses, including anxiety-like and depression-like behaviors in animals. The serotonergic system in the brain plays a pivotal role in processing anxiety. This study aimed to explore changes in concentrations of 5-hydroxytryptamine (serotonin), and the expression changes of tryptophan hydroxylase 2 (TPH2) mRNA and protein associated with anxiety-related behavioral responses under transport stress. A model of simulated transport stress was established in 40 adult male Sprague-Dawley rats, including a control group (n = 20) and a transport stress (TS) group (n = 20). The results showed that the rats in the TS group exhibited an increased feeding latency in the novelty-suppressed feeding test and a reduced frequency and dwelling time in the central area in the open-field test (OFT). Two hours following the final behavioral test, blood samples were collected. Creatine kinase (CK) activities and glucose and corticosterone concentrations in serum were significantly higher in the rats in the TS group than in the control group. Transport stress also significantly reduced the concentrations of 5-hydroxytryptamine in the hippocampus, striatum, and raphe nuclei and also reduced the expression levels of mRNA and protein for TPH2 in the raphe nuclei. Notably, the number of Fos-immunoreactive neurons was higher in the dorsal raphe nucleus under transport stress, whereas the number of 5-hydroxytryptamine-positive neurons was significantly lower. These findings are consistent with the hypothesis that the 5-hydroxytryptamine transmitter in the hippocampus, striatum, and raphe nuclei is involved in processing anxiety-related behavioral responses under transport stress. Lay summary Physiological and psychological stress responses were induced in a rat model of simulated transport stress. We examined whether serotonin in the brain may be involved in mediating behavioral responses following exposure to transport stress. Tissue concentrations of serotonin in rat brain regions, including the hippocampus, striatum, and raphe nuclei, were reduced following exposure to transport stress. Expression of tryptophan hydroxylase 2 mRNA and protein, which catalyses serotonin synthesis, as well as numbers of serotonin-immunoreactive neurons, were decreased in the brainstem raphe nuclei.

Chinese highly pathogenic porcine reproductive and respiratory syndrome virus exhibits more extensive tissue tropism for pigs.

BACKGROUND: The highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) emerging in China exhibits high fatality to pigs. However, the mechanism related to the increased pathogenicity of the virus remains unclear. In the present study, the differences in tissue tropism between the highly pathogenic PRRSV strain (JXwn06) and the low pathogenic PRRSV strain (HB-1/3.9) were investigated using PRRSV-specific immunohistochemistry (IHC) staining to provide evidence for elucidating possible mechanism of the pathogenicity of Chinese highly pathogenic PRRSV. FINDINGS: IHC examination showed that PRRSV antigen in the tissues including spleen, tonsil, thymus, kidney, cerebellum, stomach, small intestine, large intestine, turbinal bone and laryngeal cartilage was positive in more pigs inoculated with JXwn06 than HB-1/3.9, and the tissues including trachea, esophagus, liver, mandibular gland and thyroid gland were positive for viral antigen in the pigs inoculated with JXwn06, but not in the pigs inoculated with HB-1/3.9. Meanwhile, we observed that epithelium in tissues including interlobular bile duct in liver, distal renal tubule of kidney, esophageal gland and tracheal gland were positive for viral antigen only in JXwn06-inoculated pigs, and epithelium of gastric mucosa and fundic gland, and intestinal gland were positive for viral antigen in both JXwn06- and HB-1/3.9-inoculated pigs, using monoclonal antibodies to N and Nsp2 proteins. CONCLUSIONS: Taken together, these findings indicate that the highly pathogenic PRRSV JXwn06 displays an expanded tissue tropism in vivo, suggesting this may contribute to its high pathogenicity to pigs.

Microvascular endothelial cells play potential immunoregulatory roles in the immune response to foot-and-mouth disease vaccines.

Microvascular endothelial cells (MVECs) have been documented to have important immunoregulatory effects. Exploring their roles in the immune response to foot-and-mouth disease (FMD) vaccines would help to improve their efficacy. In this study, the effects of FMD vaccine 146s antigens on gene expression profiles of rat intestinal mucosal and myocardial MVECs were analysed using microarray, and their effects on transendothelial migration (TEM) of peripheral blood mononuclear cells (PBMC) were investigated by the Transwell migration assay. Both kinds of MVECs displayed significant responses to 146s antigens, and 252 and 67 genes were differentially expressed in rat intestinal mucosal and myocardial MVECs, respectively. Despite different altered gene expression patterns, many immune-associated genes were involved in both kinds of MVECs. The gene expression changes by microarray were confirmed by real-time reverse transcription-polymerase chain reaction. Transwell migration analysis indicated that the TEM of PBMC was increased by 146s antigens, which could be partially inhibited by blocking vascular cell adhesion molecule 1 in MVECs. This study suggests that MVECs play potential immunoregulatory roles in the immune response to FMD vaccines, one of which is influencing the TEM of immune cells.

Lactobacillus casei Zhang Prevents Jejunal Epithelial Damage to Early-Weaned Piglets Induced by Escherichia coli K88 via Regulation of Intestinal Mucosal Integrity, Tight Junction Proteins and Immune Factor Expression.

Farm animals such as piglets are often affected by environmental stress, which can disturb the gut ecosystem. Antibiotics were commonly used to prevent diarrhea in weaned piglets, but this was banned by the European Union due to the development of antibiotic resistance. However, the use of probiotics instead of antibiotics may reduce the risk posed by pathogenic microorganisms and reduce the incidence of gastrointestinal diseases. Therefore, this study was conducted to investigate the effects of Lactobacillus casei Zhang on the mechanical barrier and immune function of early-weaned piglets infected using Escherichia coli K88 based on histomorphology and immunology. Fourteen-day-old weaned piglets were divided into a control group and experimental groups that were fed L. casei Zhang and infected with E. coli K88 with or without prefeeding and/or postfeeding of L. casei Zhang. The L. casei Zhang dose used was 107 CFU/g diet. Jejunum segments were obtained before histological, immunohistochemical, and western blot analyses were performed. In addition, the relative mRNA expression of toll receptors and cytokines was measured. Piglets fed L. casei Zhang showed significantly increased jejunum villus height, villus height-crypt depth ratio, muscle thickness, and expression of proliferating cell nuclear antigen and tight junction proteins ZO-1 and occludin. The use of L. casei Zhang effectively reduced intestinal inflammation after infection. We found that L. casei Zhang feeding prevented the jejunum damage induced by E. coli K88, suggesting that it may be a potential alternative to antibiotics for preventing diarrhea in early-weaned piglets.

Yimu San improves obstetric ability of pregnant mice by increasing serum oxytocin levels and connexin 43 expression in uterine smooth muscle.

Prolonged farrowing remains one of the critical challenges in intensive pig farming. This study aims to explore the effects and mechanism of Yimu San (YMS), a Chinese veterinary medicine micro mist, on delivery ability with mouse models. Thirty-two pregnant mice were randomly divided into a control group and low-YMS, med-YMS, and high-YMS groups. The labor process time and stillbirth rate were recorded, the levels of serum oxytocin and prostaglandin E2 (PGE2) were measured with enzyme-linked immunosorbent assay (ELISA). Contractility measurements of the isolated uterus and the expression of connexin 43 (Cx43) in uterine smooth muscle were evaluated. The results showed that compared with the control group, the birth process time and stillbirth rate in the med-YMS and high-YMS groups were remarkably lower. The in vitro uterine contractions, levels of oxytocin, PGE2, and Cx43 in the med-YMS and high-YMS groups were significantly higher than those in the control group. The differences of the above measurements between the low-YMS group and the control group were not obvious. It can be speculated that YMS could significantly promote labor in pregnant mice by enhancing the levels of oxytocin, Cx43, and PGE2.

Characteristics of a line of Eimeria necatrix after 16 successive passages of oocysts collected after peak oocyst production.

A line of Eimeria necatrix was selected by repeated passages of oocysts that were collected after peak oocyst production from feces or cecal contents of previously infected chickens. When compared with the parent strain, the new line of E. necatrix after 16 successive passages had the following characteristics: (1) the peak of oocyst production was delayed by 2 days; (2) the sizes of 9 endogenous development stages became larger; and (3) the reproductive capacity and the immunogenicity were both enhanced. This new line of E. necatrix may be used for the development of new coccidiosis vaccines.

Lower expression of sialic acid receptors in the cecum of silky fowl (Gallus gallus domesticus Brisson) compared to white leghorn.

Avian influenza virus has received increasing attention in recent years because of the potential for recombination with the human virus. Distributions of sialic acid receptors on target cells are determinants of the susceptibilities of different species to influenza virus infection. In this study, the distribution of sialic acid receptors in the respiratory and gastrointestinal tracts of Silky Fowl and White Leghorn chickens were compared. The results showed that sialic acid-α-2,3-galactose receptors and sialic acid-α6-galactose receptors were both observed in Silky Fowl and White Leghorn, but fewer positive cells were detected in Silky Fowl with significant difference in the cecum. The lower abundance of sialic acid receptors likely results from the lower abundance of CD3 and F4/80 immune cells in the cecum of Silky Fowl.

Influence of the structural development of bursa on the susceptibility of chickens to infectious bursal disease virus.

Infectious bursal disease (IBD), caused by IBD virus (IBDV), is an acute, highly contagious immunosuppressive avian disease. Although age-dependent changes in susceptibility of chickens to IBDV have been established, the relationship between age-dependent structural changes in bursa of Fabricius and susceptibility of chickens to IBDV is still unclear. In the present study, we examined the bursa anatomical structure and pathological changes in specific-pathogen-free (SPF) white leghorn chickens 0 to 8 weeks post hatch (w.p.h.) and IBDV BC6/85-infected SPF chickens 2 to 6 w.p.h. respectively, by histology, histopathology, immunohistochemistry, and transmission electron microscopy. Almost all IBDV-exposed chickens (2 to 6 w.p.h.) were infected, with the severest bursal inflammation and complication in chickens at 3 w.p.h. Furthermore, the bursae of healthy chickens at 3 to 6 w.p.h. had decreased laminin immunoreactivities, lots of splits, and irregular shapes in basement membrane (BM) of cortico-medullary epithelium (CME), irregularly arranged CME, and large numbers of immunoglobulin M-bearing (IgM+) B lymphocytes in the medulla. The decreased barrier function of corticomedullary border and large amount of IgM+ B lymphocytes provide a chance for IBDV to easily contact and infect target cells at 3 to 6 w.p.h. By contrast, regular BM, neatly arranged CME, and few IgM+ B lymphocytes in healthy chickens younger than 2 w.p.h., as well as reduced IgM+ B lymphocytes and high immunoglobulin A (IgA) content in healthy chickens older than 8 w.p.h., were observed, suggesting that the integrity of corticomedullary border barrier, a small amount of target cells and high IgA content of the bursa could be the reasons for these chickens being less susceptible to IBDV. Although studies have shown how IBDV affects bursa, we focus first on the age-dependent changes of CME, BM of CME and IgA content, and our findings are the first to elucidate the structural development of bursa in relation to IBDV susceptibility from a morphological perspective.

Highly pathogenic porcine reproductive and respiratory syndrome virus infection results in acute lung injury of the infected pigs.

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) was firstly characterized in 2006 in China. The virus has caused great economic loss to the Chinese swine production during the past years. Herein, we experimentally infected SPF pigs using two strains of PRRSV with different pathogenicity and observed the lung pathological changes looking for new sights on the possible pathogenesis associated with the virulence of HP-PRRSV. The results indicated that the HP-PRRSV-infected pigs died and exhibited severe pathological changes of lungs featuring increased neutrophils, mast cells and mononuclear macrophages, compared with the pigs inoculated with low pathogenic (LP-) PRRSV. Furthermore, the pigs infected with HP-PRRSV showed the higher levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, interleukin (IL)-8 and histamine, leukotriene B4 (LTB4), platelet activation factor (PAF) in sera than those inoculated with LP-PRRSV. Additionally, the fibrosis of lung was observed in the HP-PRRSV-infected pigs. At present, our findings suggest that the aberrant immune responses triggered by HP-PRRSV infection are closely related to acute lung injury (ALI), and especially the pathological changes in lung vascular system are of particular significance. These associated pathological changes of lung are in part responsible for the additional morbidity and mortality observed in HP-PRRSV infection.

Susceptibility of chicken Kupffer cells to Chinese virulent infectious bursal disease virus.

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Although the effects of IBDV on bursa of Fabricius in chickens have been well reported, the impacts of IBDV on liver after IBDV infection are still unclear. In the present study, specific pathogen free (SPF) chickens were experimentally inoculated with IBDV Chinese virulent strain BC6/85, and the cells in liver and bursa were examined by immunohistochemistry and transmission electron microscopy (TEM). The congestion of liver tissue and fatty degeneration of hepatocytes were characteristics of microscopical changes in chicken liver at 3 days post infection (d.p.i.), whereas there were follicular lymphoid necrosis, apoptosis, depletion, as well as edema and congestion in bursa. In addition, the number of IBDV-positive cells peaked at 4 d.p.i. in bursa and at 3 d.p.i. in liver, respectively. With respect to ultrastructural pathological changes of hepatocytes, mitochondria swelled and nucleus deformed into an irregular shape or its chromatin peripherally condensed which indicated that the hepatocyte was at the early stage of apoptosis, and the electron-lucent lipid droplets in a variety of sizes were observed within cytoplasm. Kupffer cells became "swollen-like" and the electron-density of their cytoplasm was lower than that of cells in uninfected group. Liver glycogen deposits significantly declined from 2 to 5 d.p.i. and recovered strongly at 6 d.p.i. More importantly, KLU01 (macrophage marker) positive (KUL01(+)) cells were infiltrated in bursa and liver in IBDV-exposed chickens by immunoperoxidase staining. To demonstrate the correlation between IBDV and macrophages in bursa and liver, we further investigated the colocalization of viral antigens and macrophages by double immunofluorescence labeling. At 4 d.p.i., the percentage of double positive cells (IBDV positive and KUL01(+) cells) accounted for 26.5 percent of the total IBDV positive cells or 57 percent of the total KUL01(+) cells in bursa. In comparison, the percentage of double positive cells in liver constituted 97 percent of the total IBDV positive cells or 99 percent of the total KUL01(+) cells. These results suggest that IBDV was susceptible to KUL01(+) cells in liver (mainly Kupffer cells) and replicated in the KUL01(+) cells. By comparison with the influence of IBDV on bursa, our findings were the first to elucidate the pathological changes in liver after IBDV infection on a microscopical and ultrastructural scale, and, especially, to gain the initial insight into the susceptibility of Kupffer cells to IBDV.

Androgen inhibits abdominal fat accumulation and negatively regulates the PCK1 gene in male chickens.

Capons are male chickens whose testes have been surgically incised. Capons show a significant increase in fat accumulation compared to intact male chickens. However, while caponization leads to a significant reduction in androgen levels in roosters, little is known about the molecular mechanisms through which androgen status affects lipogenesis in avian species. Therefore, investigation of the influence of androgens on fat accumulation in the chicken will provide insights into this process. In this study, Affymetrix microarray technology was used to analyze the gene expression profiles of livers from capons and intact male chickens because the liver is the major site of lipogenesis in avian species. Through gene ontology, we found that genes involved in hepatic lipogenic biosynthesis were the most highly enriched. Interestingly, among the upregulated genes, the cytosolic form of the phosphoenolpyruvate carboxykinase (PCK1) gene showed the greatest fold change. Additionally, in conjunction with quantitative real-time PCR data, our results suggested that androgen status negatively regulated the PCK1 gene in male chickens.

Immunohistochemical location of serotonin and serotonin 2B receptor in the small intestine of pigs.

The distribution of serotonin and serotonin 2B receptor in the small intestines of pigs newborn, 5, 15 and 100 days of age were examined qualitatively and quantitatively by immunohistochemical labeling, microscopic observation and image analysis. The results showed serotonin immunopositive cells distributed diffusely among the epithelial cells of the middle and more basal parts of villi and intestinal glands in all segments of all pigs examined. Serotonin 2B receptor was first localized in the duodenum of 15-day-old pigs, whereas in 100-day-old pigs, serotonin 2B receptor was immunolabeled abundantly in all segments. Serotonin 2B receptor was distributed in the connective tissue of the small intestinal mucosa, lamina propria and in some myenteric neurons. The density of serotonin 2B receptor immunopositive cells in the duodenum of 100-day-old pigs was higher than that of 15-day-old pigs. The density of serotonin 2B receptor immunopositive cells in the duodenum was the highest among the three segments of the 100-day-old pigs. The study indicates that the distribution of serotonin 2B receptor is species different in the pig small intestine and the intensity of serotonin 2B receptor becomes stronger as the small intestine matures.