Endotoxin injection increases growth hormone and somatostatin secretion in sheep

Newcastle Disease Virus Induced Pathologies Severely Affect the Exocrine and Endocrine Functions of the Pancreas in Chickens

Newcastle disease virus (NDV) causes a highly contagious and devastating disease in poultry. ND causes heavy economic losses to the global poultry industry by decreasing the growth rate, decrease in egg production high morbidity and mortality. Although significant advances have been made in the vaccine development, outbreaks are reported in vaccinated birds. In this study, we report the damage caused by NDV infection in the pancreatic tissues of vaccinated and specific-pathogen-free chickens. The histopathological examination of the pancreas showed severe damage in the form of partial depletion of zymogen granules, acinar cell vacuolization, necrosis, apoptosis, congestion in the large and small vessels, sloughing of epithelial cells of the pancreatic duct, and mild perivascular edema. Increased plasma levels of corticosterone and somatostatin were observed in NDV-infected chicken at three- and five- days post infection (DPI). A slight decrease in the plasma concentrations of insulin was noticed at 5 DPI. Significant changes were not observed in the plasma levels of glucagon. Furthermore, NDV infection decreased the activity and mRNA expression of amylase, lipase, and trypsin from the pancreas. Taken together, our findings highlight that NDV induces extensive tissue damage in the pancreas, decreases the activity and expression of pancreatic enzymes, and increases plasma corticosterone and somatostatin. These findings provide new insights that a defective pancreas may be one of the reasons for decreased growth performance after NDV infection in chickens.

Neuroendocrine-immune interaction: Evolutionarily conserved mechanisms that maintain allostasis in an ever-changing environment

It has now become accepted that the immune system and neuroendocrine system form an integrated part of our physiology. Immunological defense mechanisms act in concert with physiological processes like growth and reproduction, energy intake and metabolism, as well as neuronal development. Not only are psychological and environmental stressors communicated to the immune system, but also, vice versa, the immune response and adaptation to a current pathogen challenge are communicated to the entire body, including the brain, to evoke adaptive responses (e.g., fever, sickness behavior) that ensure allocation of energy to fight the pathogen. This phenomenon is evolutionarily conserved. Hence it is both interesting and important to consider the evolutionary history of this bi-directional neuroendocrine-immune communication to reveal phylogenetically ancient or relatively recently acquired mechanisms. Indeed, such considerations have already disclosed an extensive "common vocabulary" of information pathways as well as molecules and their receptors used by both the neuroendocrine and immune systems. This review focuses on the principal mechanisms of bi-directional communication and the evidence for evolutionary conservation of the important physiological pathways involved.

Sustained alterations of hypothalamic tanycytes during posttraumatic hypopituitarism in male mice

Traumatic brain injury is a leading cause of hypopituitarism, which compromises patients' recovery, quality of life, and life span. To date, there are no means other than standardized animal studies to provide insights into the mechanisms of posttraumatic hypopituitarism. We have found that GH levels were impaired after inducing a controlled cortical impact (CCI) in mice. Furthermore, GHRH stimulation enhanced GH to lower level in injured than in control or sham mice. Because many characteristics were unchanged in the pituitary glands of CCI mice, we looked for changes at the hypothalamic level. Hypertrophied astrocytes were seen both within the arcuate nucleus and the median eminence, two pivotal structures of the GH axis, spatially remote to the injury site. In the arcuate nucleus, GHRH neurons were unaltered. In the median eminence, injured mice exhibited unexpected alterations. First, the distributions of claudin-1 and zonula occludens-1 between tanycytes were disorganized, suggesting tight junction disruptions. Second, endogenous IgG was increased in the vicinity of the third ventricle, suggesting abnormal barrier properties after CCI. Third, intracerebroventricular injection of a fluorescent-dextran derivative highly stained the hypothalamic parenchyma only after CCI, demonstrating an increased permeability of the third ventricle edges. This alteration of the third ventricle might jeopardize the communication between the hypothalamus and the pituitary gland. In conclusion, the phenotype of CCI mice had similarities to the posttraumatic hypopituitarism seen in humans with intact pituitary gland and pituitary stalk. It is the first report of a pathological status in which tanycyte dysfunctions appear as a major acquired syndrome.

Inhibitory effect of baicalin on iNOS and NO expression in intestinal mucosa of rats with acute endotoxemia

The mechanism by which baicalin modulated the expression of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in the mucosa of distal ileum was investigated in a rat model of acute endo-toxemia induced by intraperitoneal injection of bacterial lipopolysaccharide (LPS). The experiment demonstrated that LPS upregulated iNOS mRNA and protein expression as well as NO produc-tion (measured as the stable degradation production, nitrites). LPS not only increased toll-like receptor 4 (TLR4) and peroxisome proliferator-activated receptor gamma (PPARγ) content, but also activated p38 and activating transcription factor 2 (ATF2) and inactivated PPARγ via phosphorylation. Inhibition of p38 signalling pathway by chemical inhibitor SB202190 and small interfering RNA (siRNA) ameliorated LPS-induced iNOS generation, while suppression of PPARγ pathway by SR-202 boosted LPS-elicited iNOS expression. Baicalin treatment (I) attenuated LPS-induced iNOS mRNA and protein as well as nitrites generation, and (II) ameliorated LPS-elicited TLR4 and PPARγ production, and (III) inhibited p38/ATF2 phosphorylation leading to suppression of p38 signalling, and (IV) prevented PPARγ from phosphorylation contributing to maintainence of PPARγ bioactivity. However, SR-202 co-treatment (I) partially abrogated the inhibitory effect of baicalin on iNOS mRNA expression, and (II) partially reversed baicalin-inhibited p38 phosphorylation. In summary, baicalin could ameliorate LPS-induced iNOS and NO overproduction in mucosa of rat terminal ileum via inhibition of p38 signalling cascade and activation of PPARγ pathway. There existed a interplay between the two signalling pathways.

Biologic therapy and its effect on skeletal development in children with chronic inflammation

Chronic inflammatory conditions in children such as juvenile idiopathic arthritis, inflammatory bowel disease, cystic fibrosis and systemic lupus erythematosus can cause reduced linear growth, final height and bone mass. There are many mechanisms leading to these skeletal alterations but inflammation itself is considered to play an important role. Biologic therapy is being used increasingly for the treatment of chronic inflammatory conditions and may also be effective in improving growth and skeletal development. The main aim of this article is to summarize the effects of inflammation on growth and skeletal development and evaluate the effects of biologic therapy on growth and skeletal development in children with chronic inflammatory conditions.

Infection, immunity and the neuroendocrine response

The Central Nervous (CNS) and Immune Systems (IS) are the two major adaptive systems which respond rapidly to numerous challenges that are able to compromise health. The defensive response strictly linking innate to acquired immunity, works continuously to limit pathogen invasion and damage. The efficiency of the innate response is crucial for survival and for an optimum priming of acquired immunity. During infection, the immune response is modulated by an integrated neuro-immune network which potentiates innate immunity, controls potential harmful effects and also addresses metabolic and nutritional modifications supporting immune function. In the last decade much knowledge has been gained on the molecular signals that orchestrate this integrated adaptive response, with focus on the systemic mediators which have a crucial role in driving and controlling an efficient protective response. These mediators are also able to signal alterations and control pathway dysfunctions which may be involved in the persistence and/or overexpression of inflammation that may lead to tissue damage and to a negative metabolic impact, causing retarded growth. This review aims to describe some important signalling pathways which drive bidirectional communication between the Immune and Nervous Systems during infection. Particular emphasis is placed on pro-inflammatory cytokines, immunomodulator hormones such as Glucocorticoids (GCs), Growth hormone (GH), Insulin-like Growth Factor-1 (IGF-1), and Leptin, as well as nutritional factors such as Zinc (Zn). Finally, the review includes up-to-date information on this neuroimmune cross-talk in domestic animals. Data in domestic animal species are still limited, but there are several exciting areas of research, like the potential interaction pathways between mediators (i.e. cytokine-HPA regulation, IL-6-GCS-Zn, cytokines-GH/IGF-1, IL-6-GH-Leptin and thymus activity) that are or could be promising topics of future research in veterinary medicine.

Somatostatin infusion increases intestinal ischemia and does not improve vasoconstrictor response to norepinephrine in ovine endotoxemia

Hemodynamic support of patients with septic shock is often complicated by a tachyphylaxis against exogenous catecholamines. Because an increase in somatotropic hormones may play a pivotal role in the regulation of the inflammatory response to endotoxin, intravenous supplementation of the neuroendocrine hormone somatostatin (SOMA) may attenuate hemodynamic dysfunction resulting from endotoxemia. The objective of the present study was to assess the short-term effects of SOMA alone and in combination with norepinephrine (NE) on cardiopulmonary hemodynamics, global oxygen transport, plasma nitrate/nitrite levels, and intestinal integrity compared with single NE therapy in ovine endotoxemia. After a baseline measurement in healthy sheep (n = 16) had been performed, Salmonella typhosa endotoxin was centrally infused (10 ng x kg(-1) x min(-1)) to induce a hypotensive-hyperdynamic circulation using an established protocol. Animals surviving 16 h of endotoxemia were randomly assigned to one of the two groups (each n = 6). Sheep allocated to the SOMA + NE group received SOMA as a loading dose of 10.5 microg x kg(-1) x min(-1) for 1 h, followed by a continuous infusion of 3.5 microg x kg(-1) x min(-1) for the next 2 h. After the SOMA loading dose had been given, NE was concurrently infused (0.3 microg x kg(-1) x min(-1)) for 2 h. In the NE group (control), NE (0.3 microg x kg(-1) x min(-1)) was continuously infused for 3 h. Endotoxemia caused a decrease in MAP and systemic vascular resistance index in both groups, but to a greater extent in the NE group. Arterial hypotension persisted despite administration of the study drugs. Infusion of SOMA alone and in combination with NE did not significantly increase systemic vascular resistance index. Neither SOMA nor NE infusion alone affected pulmonary vasoregulation. Plasma nitrate/nitrite levels did not differ between groups. However, combined infusion of SOMA and NE significantly increased arterial lactate concentrations, oxygen consumption index, and oxygen extraction rate (P < 0.05) and aggravated ileal mucosal injury. In conclusion, short-term treatment with SOMA failed to attenuate cardiocirculatory shock resulting from endotoxemia and did not improve vasopressor response to NE. In addition, combined SOMA and NE therapy resulted in intestinal injury. Therefore, SOMA does not seem to represent a therapeutic option to treat arterial hypotension resulting from sepsis and systemic inflammatory response syndrome.

Comparative aspects of the endotoxin- and cytokine-induced endocrine cascade influencing neuroendocrine control of growth and reproduction in farm animals

Disease in animals is a well-known inhibitor of growth and reproduction. Earlier studies were initiated to determine the effects of endotoxin on pituitary hormone secretion. These studies found that in sheep, growth hormone (GH) concentration was elevated, whereas insulin-like growth factor-I (IGF-I) was inhibited, as was luteinizing hormone (LH). Examination of the site of action of endotoxin in sheep determined that somatotropes expressed the endotoxin receptor (CD14) and that both endotoxin and interleukin-I beta activated GH secretion directly from the pituitary. In the face of elevated GH, there is a reduction of IGF-I in all species examined. As GH cannot activate IGF-I release during disease, there appears to be a downregulation of GH signalling at the liver, perhaps related to altered nitration of Janus kinase (JAK). In contrast to GH downregulation, LH release is inhibited at the level of the hypothalamus. New insights have been gained in determining the mechanisms by which disease perturbs growth and reproduction, particularly with regard to nitration of critical control pathways, with this perhaps serving as a novel mechanism central to lipopolysaccharide suppression of all signalling pathways. This pathway-based analysis is critical to the developing novel strategies to reverse the detrimental effect of disease on animal production.

Bidirectional communication: Growth and immunity in domestic livestock1,2,3,4

Evidence continues to mount supporting the existence of a bidirectional communication network between the immune system and the somatotropic axis in a variety of species. For more than 4 decades, researchers have sought and identified linkages between the growth axis and the immune system. Although significant advances have been made with regard to elucidation of various bidirectional communication pathways between the immune system and growth axis in humans and rodents, the current paper focuses on the relationships between the immune system and somatotropic axis in sheep, cattle, and swine. Aspects from historical and current research associated with changes in somatotropic function following immune challenges with endotoxin, parasites, viruses, and bacteria have been provided. Collectively, these studies demonstrate that a bidirectional communication network, similar to that described in humans and rodents, also exists in a variety of domestic livestock. Identifying and understanding this bidirectional communication network could have significant economic benefits if it leads to intervention strategies to prevent production losses associated with sickness and disease.

Interleukin-1beta and tumor necrosis factor-alpha mediation of endotoxin action on growth hormone

In humans and sheep, endotoxin (LPS) administration results in increased growth hormone (GH) concentrations. To determine the role of cytokines in the effect of LPS on GH, sheep were challenged with IL-1beta or TNF-alpha. GH data were compared with results with LH, where the major effects of LPS are known to act via the hypothalamus. Intracerebroventricular (icv) administration of IL-1beta or TNF-alpha did not alter plasma concentrations of GH. Endotoxin was then administered intravenously (iv) in combination with icv injection of IL-1 receptor antagonist (IL-1RA), TNF antagonist (sTNF-R1), or saline. Administration of LPS increased GH (P < 0.0001), although coadministration of IL-1ra or sTNF-R1 icv did not alter GH response to LPS. In contrast, plasma concentrations of LH were profoundly inhibited by icv administration of either cytokine (P < 0.03), but the LH response to LPS was not altered by cytokine antagonists. Intravenous administration of either IL-1beta or TNF-alpha increased plasma concentrations of GH (P < 0.0001). Administration of IL-1RA and sTNF-R1 iv prevented LPS-induced increases in GH. Although LH was suppressed by high iv doses of IL-1beta (P = 0.0063), the antagonists did not alter the LH response to LPS. To determine whether LPS might directly activate GH release, confocal microscopy revealed colocalization of CD14, the LPS receptor, with GH and, to a lesser extent, LH and some prolactin (PRL)-containing cells, but not ACTH or TSH. These data are consistent with the effects of LPS on GH secretion originating through peripheral cytokine presentation to the pituitary, as well as a potential to act directly on selective populations of pituitary cells via CD14.

Vasoactive Intestinal Peptide (VIP) and Pituitary Adenylate Cyclase-Activation Polypeptide (PACAP) Protect Mice from Lethal Endotoxemia Through the Inhibition of TNF-α and IL-6

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) down-regulate cytokine production. Because human septic shock involves excessive cytokine production, the effect of VIP/PACAP was investigated in a high endotoxemia murine model. Both peptides protect against endotoxin-induced lethality and prevent septic shock-associated histopathological alterations. VIP/PACAP reduce serum and peritoneal TNF-α and IL-6, suggesting that the protective effect is exerted by inhibiting the production of endogenous TNF-α/IL-6. Consistent with this mechanism, VIP does not protect against septic shock induced by exogenous TNF-α. The immunomodulatory role of VIP in vivo is supported by the appearance of high levels of VIP in serum and peritoneal fluid following LPS administration. Thus, the neuropeptides VIP/PACAP protect from the lethal effect of high endotoxemia, presumably by down-regulating TNF-α and IL-6 production, and may offer an alternative in the treatment of human septic shock syndrome.