Differential effects of hemorrhage and LPS on tissue TNF-alpha, IL-1 and associate neuro-hormonal and opioid alterations

Invited review: Compartmentalization of the inflammatory response in sepsis and SIRS

Sepsis and systemic inflammatory response syndrome (SIRS) are associated with an exacerbated production of both pro- and anti-inflammatory mediators that are mainly produced within tissues. Although a systemic process, the pathophysiological events differ from organ to organ, and from organ to peripheral blood, leading to the concept of compartmentalization. The nature of the insult ( e.g. burn, hemorrhage, trauma, peritonitis), the cellular composition of each compartment ( e.g . nature of phagocytes, nature of endothelial cells), and its micro-environment ( e.g. local presence of granulocyte-macrophage colony stimulating factor [GM-CSF] in the lungs, low levels of arginine in the liver, release of endotoxin from the gut), and leukocyte recruitment, have a great influence on local inflammation and on tissue injury. High levels of pro-inflammatory mediators ( e.g. interleukin-1 [IL-1], tumor necrosis factor [TNF], gamma interferon [IFN-γ], high mobility group protein-1 [HMGB1], macrophage migration inhibitory factor [MIF]) produced locally and released into the blood stream initiate remote organ injury as a consequence of an organ cross-talk. The inflammatory response within the tissues is greatly influenced by the local delivery of neuromediators by the cholinergic and sympathetic neurons. Acetylcholine and epinephrine contribute with IL-10 and other mediators to the anti-inflammatory compensatory response initiated to dampen the inflammatory process. Unfortunately, this regulatory response leads to an altered immune status of leukocytes that can increase the susceptibility to further infection. Again, the nature of the insult, the nature of the leukocytes, the presence of circulating microbial components, and the nature of the triggering agent employed to trigger cells, greatly influence the immune status of the leukocytes that may differ from one compartment to another. While anti-inflammatory mediators predominate within the blood stream to avoid igniting new inflammatory foci, their presence within tissues may not always be sufficient to prevent the initiation of a deleterious inflammatory response in the different compartments.

Acute alcohol intoxication prolongs neuroinflammation without exacerbating neurobehavioral dysfunction following mild traumatic brain injury

Traumatic brain injury (TBI) represents a leading cause of death and disability among young persons with ∼1.7 million reported cases in the United States annually. Although acute alcohol intoxication (AAI) is frequently present at the time of TBI, conflicting animal and clinical reports have failed to establish whether AAI significantly impacts short-term outcomes after TBI. The objective of this study was to determine whether AAI at the time of TBI aggravates neurobehavioral outcomes and neuroinflammatory sequelae post-TBI. Adult male Sprague-Dawley rats were surgically instrumented with gastric and vascular catheters before a left lateral craniotomy. After recovery, rats received either a primed constant intragastric alcohol infusion (2.5 g/kg+0.3 g/kg/h for 15 h) or isocaloric/isovolumic dextrose infusion followed by a lateral fluid percussion TBI (∼1.4 J, ∼30 ms). TBI induced apnea and a delay in righting reflex. AAI at the time of injury increased the TBI induced delay in righting reflex without altering apnea duration. Neurological and behavioral dysfunction was observed at 6 h and 24 h post-TBI, and this was not exacerbated by AAI. TBI induced a transient upregulation of cortical interleukin (IL)-6 and monocyte chemotactic protein (MCP)-1 mRNA expression at 6 h, which was resolved at 24 h. AAI did not modulate the inflammatory response at 6 h but prevented resolution of inflammation (IL-1, IL-6, tumor necrosis factor-α, and MCP-1 expression) at 24 h post-TBI. AAI at the time of TBI did not delay the recovery of neurological and neurobehavioral function but prevented the resolution of neuroinflammation post-TBI.

Contribution of α - and β -Adrenergic Mechanisms to the Development of Pulmonary Edema

Endogenous or exogenous catecholamines can induce pulmonary edema (PE). This may occur in human pathologic conditions such as in pheochromocytoma or in neurogenic pulmonary edema (NPE) but can also be provoked after experimental administration of adrenergic agonists. PE can result from stimulation with different types of adrenergic stimulation. With α-adrenergic treatment, it develops more rapidly, is more severe with abundant protein-rich fluid in the alveolar space, and is accompanied by strong generalized inflammation in the lung. Similar detrimental effects of α-adrenergic stimulation have repeatedly been described and are considered to play a pivotal role in NPE or in PE in patients with pheochromocytoma. Although β-adrenergic agonists have often been reported to prevent or attenuate PE by enhancing alveolar fluid clearance, PE may also be induced by β-adrenergic treatment as can be observed in tocolysis. In experimental models, infusion of β-adrenergic agonists induces less severe PE than α-adrenergic stimulation. The present paper addresses the current understanding of the possible contribution of α- and β-adrenergic pathways to the development of PE.

Sympathetic modulation of the host defense response to infectious challenge during recovery from hemorrhage

BACKGROUND

Trauma/hemorrhage (TxHem) is associated with an immediate pro-inflammatory response that, if exaggerated or prolonged, is thought to contribute to the subsequent immunosuppression that characterizes the period after injury. Previously we have demonstrated that chemical sympathectomy (SNSx) accentuates this immediate pro-inflammatory response to TxHem. These findings suggest that the noradrenergic system plays a critical role in limiting the magnitude of the inflammatory response during TxHem and preserving the integrity of the host defense response to a subsequent infectious challenge during the period after TxHem.

OBJECTIVE

To examine the contribution of tissue norepinephrine to the host defense response to an infectious challenge during recovery from TxHem.

METHODS

Male Sprague-Dawley rats underwent SNSx (6-hydroxydopamine, i.p. daily for 3 days) prior to vascular catheter implantation. Conscious, unrestrained rats were subjected to traumatic injury (muscle crush) prior to a fixed-pressure hemorrhage (40 mm Hg for 60 min) and fluid resuscitation followed 24 h later by cecal ligation and puncture (CLP).

RESULTS

SNSx impaired the hemodynamic and thermoregulatory response to hemorrhage as indicated by decreased basal blood pressure, impaired blood pressure recovery during fluid resuscitation, and greater hypothermia after CLP. Furthermore, SNSx accentuated the TNF-alpha, IL-1, IL-6, and IL-10 response to TxHem + infection in plasma 6 h after CLP and in peritoneal lavage fluid 24 h after CLP.

CONCLUSION

These results indicate that the integrity of the noradrenergic system is necessary for adequate hemodynamic, thermoregulatory, and inflammatory responses to infection during the period following TxHem.

Protein kinases, TNF-{alpha}, and proteasome contribute in the inhibition of fructose intestinal transport by sepsis in vivo

Lipopolysaccharide (LPS) endotoxin is a causative agent of sepsis. The aim of this study was to examine LPS effects on intestinal fructose absorption and to decipher mechanisms. Sepsis was induced by intravenous injection of LPS in rabbits. The ultrastructural study and DNA fragmentation patterns were identical in the intestine of LPS and sham animals. LPS treatment reduced fructose absorption altering both mucosal-to-serosal transepithelial fluxes and uptake into brush border membrane vesicles (BBMVs). Cytochalasin B was ineffective on fructose uptake, indicating that GLUT5, but not GLUT2, transport activity was targeted. GLUT5 protein levels in BBMvs were lower in LPS than in sham-injected rabbits. Thus lower fructose transport resulted from lower levels of GLUT5 protein. LPS treatment decreased GLUT5 levels by proteasome-dependent degradation. Specific inhibitors of PKC, PKA, and MAP kinases (p38MAPK, JNK, MEK1/2) protected fructose uptake from adverse LPS effect. Moreover, a TNF-alpha antagonist blocked LPS action on fructose uptake. We conclude that intestinal fructose transport inhibition by LPS is associated with diminished GLUT5 numbers in the brush border membrane of enterocytes triggered by activation of several interrelated signaling cascades and proteasome degradation.

Effect of exogenous catecholamines on tumor necrosis factor alpha, interleukin-6, interleukin-10 and beta-endorphin levels following severe trauma

Cytokines and endogenous opioids are mediators of the post traumatic inflammatory response. The aim of this study was to determine the effect of exogenous catecholamines on tumor necrosis factor alpha (TNFa), interleukin-6 (IL-6), interleukin-10 (IL-10) and beta(beta)-endorphin levels in patients with severe trauma, during the first 24 h after injury. Forty four traumatized patients with haemorrhage class III and IV were included in the study. Patients were divided in two groups: Group 1 (adrenergic, n=22) and Group 2 (non adrenergic, n=22), depending on the use of exogenous catecholamines. Blood samples were collected at 0, 2, 4 and 24 h time points. Baseline values were different between the two groups, but an altered pattern of release was observed for TNFa, IL-6, IL-10 and beta-endorphin levels in patients treated with catecholamines. ICU stay was longer for the adrenergic group, while survival after 1 month was significantly lower. Findings support an altered pattern of cytokine release during the early phase after trauma, probably due to catecholamine presence.

Pathogenesis of hepatic encephalopathy: the tumour necrosis factor-alpha theory

Hepatic encephalopathy (HE) is a major complication for acute and chronic liver failure. Despite several decades of intensive clinical and basic research, the pathogenesis of HE is still incompletely understood, and the precise mechanisms causing brain dysfunction in liver failure are still not fully established. Several theories concerning the pathogenesis of HE have been previously suggested, including the ammonia theory, which received the most attention. These theories are not mutually exclusive and the validity of none of them has been definitely proved experimentally. In this review article, an attractive theory concerning the pathogenesis of HE, the tumour necrosis factor-alpha (TNF) theory, is presented and comprehensively discussed after accumulation of sufficient data which indicate that the pro-inflammatory cytokine, TNF, is strongly involved in the pathogenesis of HE associated with both acute and chronic liver failure. This theory seems to be superior to all other previous theories in the pathogenesis of HE, and may induce development of other beneficial therapeutical modalities for HE directed towards inhibition of TNF production and/or action, and towards enhancement of its degradation.

Liver cytokine production and ICAM-1 expression following bone fracture, tissue trauma, and hemorrhage in middle-aged mice

Although studies have indicated that hemorrhagic shock and resuscitation produces hepatic damage by mechanisms involving adhesion molecules in endothelial cells and hepatocytes, it is not known if there is any difference in the extent of hepatic damage following bone fracture, soft tissue trauma, and hemorrhage (Fx-TH) between young and middle-aged animals. To study this, young (6-8 wk) and middle-aged (approximately 12 mo) C3H/HeN male mice were subjected to a right lower leg fracture, soft tissue trauma, (i.e., midline laparotomy), and hemorrhage (blood withdrawal to decrease the blood pressure to 35 +/- 5 mmHg for 90 min) followed by resuscitation with four times the shed blood volume in the form of lactated Ringer solution. Mice were euthanized 24 h later, and liver tissues were harvested. Total bilirubin levels in the hepatocyte extract increased markedly following Fx-TH in both groups of mice; however, the increase in middle-aged mice was significantly higher compared with young mice. TNF-alpha and IL-6 levels in the hepatocyte extract following Fx-TH increased significantly in middle-aged mice but remained unchanged in young mice. IL-10 levels significantly decreased in middle-aged mice following Fx-TH but remained unchanged in young mice. Kupffer cells from middle-aged mice produced significantly higher IL-6 and IL-10 levels compared with young mice. Protein levels and mRNA expression of ICAM-1 in hepatocytes were also significantly higher in middle-aged mice compared with young mice following Fx-TH. These results collectively suggest that the extent of hepatic damage following Fx-TH is dependent on the age of the subject.

Androstenetriol improves survival in a rodent model of traumatic shock

Trauma results in activation of the hypothalamic-pituitary-adrenal axis to mediate a cascade of neurohormonal changes as a defensive mechanism. Its prolongation, however, leads to a hypermetabolic, hypoperfused, and immunosuppressed state, setting the stage for subsequent sepsis and organ failure. Androstenetriol (5-androstene-3beta, 7beta, 17betatriol - AET), a metabolite of dehydroepiandrosterone, up-regulates the host immune response markedly, prevents immune suppression and controls inflammation, leading to improved survival after lethal infections by several diverse pathogens and lethal radiation. Such actions may be useful in improving survival from traumatic shock.

HYPOTHESIS

The neurosteroid AET will increase survival following traumatic shock.

METHODS

A combat relevant model of traumatic shock was used. Male Sprague-Dawley rats were anesthetized, catheterized and subjected to soft tissue injury (laparotomy). Animals were allowed to regain consciousness over the next 0.5 h and then bled 40% of their blood volume over 15 min. Forty-five minutes after the onset of hemorrhage animals were randomized to receive either a single subcutaneous dose of AET (40 mg/kg, sc) or vehicle (methylcellulose). Volume resuscitation consisted of l-lactated Ringer's (three times the shed blood volume), followed by packed red blood cells (one-third shed red cell volume). Animals were observed for three days.

RESULTS

A total of 24 animals were studied. Of the 12 animals randomized to receive AET, all (100%) survived compared to 9 of 12 animals (75%) randomized to receive the vehicle (p < 0.05).

CONCLUSION

AET significantly improved survival when administered subcutaneously in a single dose in this rodent model of traumatic shock. Further survival and mechanism studies are warranted.

ALTERED HEMODYNAMIC COUNTER-REGULATION TO HEMORRHAGE BY ACUTE MODERATE ALCOHOL INTOXICATION

The incidence of traumatic injury, frequently associated with hemorrhagic shock, is higher in the alcohol-intoxicated individual. The outcome, as it pertains to both morbidity and mortality of this population, is partly dependent on duration of alcohol exposure and levels of blood alcohol at time of injury. In previous studies, we demonstrated that prolonged alcohol intoxication (15-h duration) produces marked hemodynamic instability and exacerbated early lung proinflammatory cytokine expression after hemorrhagic shock. The present study examines whether a shorter and more modest period of alcohol intoxication is sufficient to alter hemodynamic and proinflammatory responses to hemorrhagic shock. Chronically instrumented, conscious male Sprague-Dawley rats (250-300 g) received a single intragastric bolus of alcohol (1.75 g/kg) 30 min before the administration of fixed-volume (50%) hemorrhagic shock, followed by fluid resuscitation with Ringer lactate. Time-matched controls were administered on isocaloric dextrose bolus (3 g/kg). Alcohol (blood alcohol concentration, 152 +/- 10 mg/dL) produced a 14% decrease in basal mean arterial blood pressure and a more profound hypotensive response to equal blood loss. The 2-fold rise in circulating norepinephrine levels was similar in alcohol- and dextrose-treated hemorrhaged animals despite greater hypotension in alcohol-treated animals. Significant upregulation in lung and spleen interleukin (IL) 1, IL-6, IL-10, and tumor necrosis factor alpha expression was observed immediately after hemorrhage and fluid resuscitation, as previously reported. Only the hemorrhage-induced rise in lung IL-6 and tumor necrosis factor alpha was prevented by alcohol administration. In contrast, spleen cytokine responses to hemorrhage were not altered by alcohol administration. These results indicate that moderate acute alcohol intoxication results in significant modulation of hemodynamic and neuroendocrine responses to hemorrhagic shock.

Differential induction of adrenomedullin, interleukins and tumour necrosis factor-alpha by lipopolysaccharide in rat tissues in vivo

The aim of the present study was to determine the temporal changes in tissue adrenomedullin (AM) and cytokine contents and cytokine and preproAM mRNA levels in the kidney, liver, adrenal gland and spleen of lipopolysaccharide (LPS)-treated rats. Rats were injected with LPS (10 mg/kg, i.p.). Radioimmunoassay and solution hybridization-RNase protection assays were used to follow the changes in AM and its mRNA levels, respectively; ELISA and reverse transcription-polymerase chain reaction were used to follow the changes in cytokines and their mRNA levels, respectively. In the kidney, the preproAM mRNA levels were increased 1 and 3 h after LPS treatment, whereas AM levels were decreased at 3 h. Interleukin (IL)-6 and IL-1beta levels were increased at 3 and 6 h, respectively. The preproAM mRNA levels were elevated in the liver 3 h after LPS injection. Concentrations of tumour necrosis factor (TNF)-alpha and IL-1beta were increased at l and 6 h, respectively. There were no changes in the levels of either preproAM mRNA or AM in the adrenal gland and the spleen. In the spleen, TNF-alpha levels were elevated at 1 and 3 h after LPS injection and IL-1beta was elevated at 1 and 6 h after LPS injection, whereas in the adrenal gland IL-1beta was elevated at 6 h after injection. The mRNA levels of the three cytokines were elevated at all three time intervals examined in the kidney, liver, adrenal gland and spleen, with the exception that TNF-alpha mRNA was not elevated in the adrenal gland at 6 h after LPS injection and IL-1beta mRNA was not elevated in the spleen at 3 and 6 h. The plasma concentrations of TNF-alpha were increased at 1 and 3 h after LPS injection, whereas plasma concentration of IL-1beta and IL-6 were elevated at 3 and 6 h for both. The present results suggest that the biosynthesis and secretion of AM may be differentially regulated in various tissues of rats injected with LPS and that AM may interact with cytokines during inflammation.

Opioids and opiates: analgesia with cardiovascular, haemodynamic and immune implications in critical illness

Traumatic injury, surgical interventions and sepsis are amongst some of the clinical conditions that result in marked activation of neuroendocrine and opiate responses aimed at restoring haemodynamic and metabolic homeostasis. The central activation of the neuroendocrine and opiate systems, known collectively as the stress response, is elicited by diverse physical stressor conditions, including ischaemia, glucopenia and inflammation. The role of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system in counterregulation of haemodynamic and metabolic alterations has been studied extensively. However, that of the endogenous opiates/opioid system is still unclear. In addition to activation of the opiate receptor through the endogenous release of opioids, pharmacotherapy with opiate receptor agonists is frequently used for sedation and analgesia of injured, septic and critically ill patients. How this affects the haemodynamic, cardiovascular, metabolic and immune responses is poorly understood. The variety of opiate receptor types, their specificity and ubiquitous location both in the central nervous system and in the periphery adds additional complicating factors to the clear understanding of their contribution to the stress response to the various physical perturbations. This review aims at discussing scientific evidence gathered from preclinical studies on the role of endogenous opioids as well as those administered as pharmacological agents on the host cardiovascular, neuroendocrine, metabolic and immune response mechanisms critical for survival from injury in perspective with clinical observations that provide parallel assessment of relevant outcome measures. When possible, the clinical relevance and corresponding scenarios where this evidence can be integrated into our understanding of the clinical implications of opiate effects will be examined. Overall, the scientific basis to enhance clinical judgment and expectations when using opioid sedation and analgesia in the management of the injured, septic or postsurgical patient will be discussed.

TSC for hemorrhagic shock: effects on cytokines and blood pressure

Previous studies have shown that administering trans-sodium crocetinate (TSC) as a treatment of hemorrhagic shock leads to increased whole-body oxygen consumption and survival as well as protection of the liver and kidney. It has been suggested that TSC increases oxygen delivery by increasing the diffusivity of oxygen through plasma. However, as with any novel mechanism of action, there are always questions about whether the results could also be ascribed to other, previously described mechanisms of action. This study was designed to look at some aspects of that by examining the effect of different TSC dosing regimens on the blood pressure and the production of cytokines after hemorrhage because both responses have been reported with compounds that act via other mechanisms. In a constant-pressure rat model of hemorrhagic shock, it was seen that a singe bolus injection of TSC results in an immediate but transient increase in the arterial blood pressure. This is similar to the effect reported previously for using 100% oxygen. It was also found that if the TSC injections were repeated periodically over an hour, a sustained increase in the blood pressure would occur. Because inflammatory cytokines have been implicated in mortality and tissue damage, it has been suggested that TSC may affect the production of cytokines. Thus, the effect of TSC on the production of TNF-alpha and IL-10 was also examined. The data show that treatment with TSC results in lower concentrations of TNF-alpha in the liver and spleen as well as lower concentrations of IL-10 in the spleen. Again, similar effects on other cytokines have been seen with 100% oxygen. These results support the hypothesis that the effects of TSC on hemorrhagic shock are mediated via an effect on oxygen.

Adrenomedullin gene expression and levels in the cardiovascular system after treatment with lipopolysaccharide

To study the effect of septicaemia, the temporal changes in tissue adrenomedullin (AM) and preproAM mRNA levels were studied in the heart and blood vessels after lipopolysaccharide (LPS) injection. Radioimmunoassay and solution hybridization-RNase protection assays were used to follow the changes in AM and its mRNA levels respectively after intraperitoneal injection of 10 mg/kg LPS in rats. The preproAM mRNA levels increased at 1 h in the right atrium after LPS injection, while the AM contents decreased at 1 h in the left atrium. The preproAM mRNA levels increased at 3 and 6 h in the left ventricle, whereas it increased at 6 h in the right ventricles after LPS injection. There was an increase in preproAM mRNA levels at 1 and 3 h in the mesenteric artery, while AM levels were increased at 1, 3 and 6 h. However, there were no such changes in the thoracic aorta. There were also increases in tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and IL-6 in the heart, and in the mesenteric artery (TNF-alpha and IL-1beta) and in thoracic aorta (IL-1beta and IL-6). The present results suggest that the biosynthesis and secretion of AM may be increased in cardiovascular tissues of rats injected with LPS, and that AM may play multiple roles in inflammation.

Consequences of alcohol-induced early dysregulation of responses to trauma/hemorrhage

Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Studies from our laboratory have been designed to examine the early hemodynamic, proinflammatory, and neuroendocrine alterations in responses to hemorrhagic shock in surgically catheterized, conscious, unrestrained, male Sprague-Dawley rats during acute alcohol intoxication (1.75-g/kg bolus, followed by a constant 15-h infusion at a rate of 250-300 mg/kg/h). With both fixed-pressure (40 mm Hg) and fixed-volume (50%) hemorrhagic shock, followed by fluid resuscitation with Ringer's lactate, acute (15 h) alcohol intoxication has been shown to impair significantly the immediate hemodynamic, metabolic, and inflammatory counterregulatory responses to hemorrhagic shock. Alcohol intoxication enhanced hemodynamic instability during blood loss and impaired the recovery of mean arterial blood pressure during fluid resuscitation. Activation of neuroendocrine pathways involved in restoring hemodynamic stability was significantly attenuated in alcohol-intoxicated hemorrhaged animals. The hemodynamic and neuroendocrine impairment is associated with enhanced expression of lung and spleen tumor necrosis factor, and it suppressed circulating neutrophil function. In addition, neuroimmune regulation of cytokine production by spleen-derived macrophages obtained from alcohol-intoxicated hemorrhaged animals was impaired when examined in vitro. We hypothesize that impaired neuroendocrine activation contributes to hemodynamic instability, which, in turn, prolongs tissue hypoperfusion and enhances risk for tissue injury. Specifically, the early dysregulation in counterregulatory responses is hypothesized to affect host defense mechanisms during the recovery period. We examined host response to systemic (cecal ligation and puncture) and localized (pneumonia) infectious challenge in animals recovering from hemorrhage during acute alcohol intoxication. Increased morbidity and mortality from infection were observed in alcohol-intoxicated hemorrhaged animals. Our results indicate that alcohol-induced alterations in early hemodynamic and neuroimmune responses to shock have an impact on susceptibility to an infectious challenge during the early recovery period.

Heme oxygenase-1 in cholecystokinin-octapeptipe attenuated injury of pulmonary artery smooth muscle cells induced by lipopolysaccharide and its signal transduction mechanism

AIM: To study the effect of cholecystokinin-octapeptide (CCK-8) on lipopolysaccharide (LPS) -induced pulmonary artery smooth muscle cell (PASMCs) injury and the role of heme oxygenase-1 (HO-1), and to explore the regulation mechanism of c-Jun N-terminal kinase (JNK) and activator protein-1 (AP-1) signal transduction pathway in inducing HO-1 expression further.

METHODS: Cultured PASMCs were randomly divided into 4 or 6 groups: normal culture group, LPS (10 mg/L), CCK-8 (10^-6 mol/L) plus LPS (10 mg/L) group, CCK-8 (10^-6 mol/L) group, zinc protoporphyrin 9 (ZnPPIX) (10^{- 6} mol/L) plus LPS (10 mg/L) group, CCK-8 (10^-6 mol/L) plus ZnPPIX and LPS (10 mg/L) group. Seven hours after LPS administration, ulterstructrual changes and content of malondialdehyde (MDA) of PASMCs in each group were investigated by electron microscopy and biochemical assay respectively. HO-1 mRNA and protein of PASMCs in the former4 groups were examined by reverse transcriptase polymerase chain reaction (RT-PCR) and immunocytochemistry staining. Changes of c-fos expression and activation of JNK of PASMCs in the former 4 groups were detected with immunocytochemistry staining and Western blot 30 min after LPS administration.

RESULTS: The injuries of PASMCs and the increases of MDA content induced by LPS were alleviated and significantly reduced by CCK-8 (P < 0.05). The specific HO-1 inhibitor-ZnPPIX could worsen LPS-induced injuries and weaken the protective effect of CCK-8. The expressions of c-fos, p-JNK protein and HO-1 mRNA and protein were all slightly increased in LPS group, and significantly enhanced by CCK-8 further (P < 0.05).

CONCLUSION: HO-1 may be a key factor in CCK-8 attenuated injuries of PASMCs induced by LPS, and HO-1 expression may be related to the activation of JNK and activator protein (AP-1).

Acute Alcohol Intoxication During Hemorrhagic Shock: Impact on Host Defense From Infection

BACKGROUND

Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Our studies have demonstrated that acute alcohol intoxication significantly impairs the immediate hemodynamic, metabolic, and inflammatory responses to hemorrhagic shock. This study investigated whether acute alcohol intoxication during hemorrhagic shock would alter the outcome from an infectious challenge during the initial 24 hr recovery period.

METHODS

Chronically catheterized male Sprague Dawley rats were randomized to acute alcohol intoxication (EtOH; 1.75 g/kg bolus followed by a constant 15 hr infusion at 250-300 mg/kg/hr) or isocaloric isovolemic dextrose infusion (dex; 3 ml + 0.375 ml/hr). EtOH and dex were assigned to either fixed-volume (50%) hemorrhagic shock followed by fluid resuscitation with Ringer's lactate (EtOH/hem, dex/hem) or sham hemorrhagic shock (EtOH/sham, dex/sham). Indexes of circulating neutrophil function (apoptosis, phagocytosis, oxidative burst) were obtained at baseline, at completion of hemorrhagic shock, and at the end of fluid resuscitation. Bacterial clearance, lung cytokine expression, and myeloperoxidase activity were determined at 6 and 18 hr after an intratracheal challenge with Klebsiella pneumoniae (10 colony-forming units).

RESULTS

Mean arterial blood pressure was significantly lower in acute alcohol intoxication-hemorrhagic shock animals throughout the hemorrhagic shock. In sham animals, acute alcohol intoxication alone did not produce significant changes in neutrophil apoptosis or phagocytic activity but significantly suppressed phorbol myristic acid (PMA)-stimulated oxidative burst. Hemorrhagic shock produced a modest increase in neutrophil apoptosis and suppression of neutrophil phagocytic capacity but significantly suppressed PMA-stimulated oxidative burst. Acute alcohol intoxication exacerbated the hemorrhagic shock-induced neutrophil apoptosis and the hemorrhagic shock-induced suppression of phagocytosis without further affecting PMA-stimulated oxidative burst. Fluid resuscitation did not restore neutrophil phagocytosis or oxidative burst. Acute alcohol intoxication decreased (-40%) 3-day survival from K. pneumoniae in hemorrhagic shock animals, impaired bacterial clearance during the first 18 hr postinfection, and prolonged lung proinflammatory cytokine expression.

CONCLUSIONS

These results demonstrate that the early alterations in metabolic and inflammatory responses to hemorrhagic shock produced by acute alcohol intoxication are associated with neutrophil dysfunction and impaired host response to a secondary infectious challenge leading to increased morbidity and mortality.

Contribution of the adrenal glands and splenic nerve to LPS-induced splenic cytokine production in the rat

Both the hypothalamic pituitary adrenal axis (HPAA) and the sympathetic nervous system (SNS) can inhibit immune function and are regarded as the primary efferent pathways for neural-immune interactions. To determine if this relationship is maintained in vivo in response to an inflammatory stimulus, rats were injected intravenously (iv) with various doses of lipopolysaccharide (LPS) and splenic cytokine mRNA and protein levels were measured at several dose and time intervals post-injection. The spleen was chosen as the target organ because both the neural and hormonal inputs to the spleen can be selectively removed by splenic nerve cut (SNC) and adrenalectomy (ADX), respectively. Data from our dose response studies established that maximum levels of splenic cytokines were induced in response to relatively low doses of LPS. Minimal changes in LPS-induced splenic cytokine levels were observed in response to ADX, SNC, or a combination of the two procedures across several doses of LPS. These results suggest that there are aspects of immune regulation that are functionally removed from these central modulatory systems and that the counter-regulatory responses induced by LPS have minimal impact on the concurrent induction of cytokines by this inflammatory stimulus. The conceptual model of neural-immune regulation as an inhibitory feedback system, at least with regards to the early activational effects induced by an inflammatory stimulus, was not supported by these studies.

Saccharated colloidal iron enhances lipopolysaccharide-induced nitric oxide production in vivo

We investigated the effects of iron on the production of nitric oxide (NO), inducible NO synthase (iNOS), and plasma cytokines induced by lipopolysaccharide (LPS) in vivo. Male Wistar rats were preloaded with a single intravenous injection of saccharated colloidal iron (Fesin, 70 mg iron/kg body weight) or normal saline as a control, and then given an intraperitoneal injection of LPS (5.0 mg/kg body weight). Rats, preloaded with iron, had evidence of both iron deposition and strong iNOS induction in liver Kupffer cells upon injection of LPS; phagocytic cells in the spleen and lung had similar findings. LPS-induced NO production in iron-preloaded rats was significantly higher than control rats as accessed by NO-hemoglobin levels measured by ESR (electron spin resonance) and NOx (nitrate plus nitrite) levels. Western blot analysis showed that iron preloading significantly enhanced LPS-induced iNOS induction in the liver, but not in the spleen or lung. LPS-induced plasma levels of IL-6, IL-1beta, and TNF-alpha were also significantly higher in iron-preloaded rats as shown by ELISA, but IFN-gamma levels were unchanged. We conclude that colloidal-iron phagocytosed by liver Kupffer cells enhanced LPS-induced NO production in vivo, iNOS induction in the liver, and release of IL-6, IL-1beta, and TNF-alpha.

Endogenous opioid analgesia in hemorrhagic shock

BACKGROUND

Hemorrhagic shock produces an immediate activation of the autonomic nervous system and endogenous opioid pathways. Our studies have demonstrated that endogenous opioid activation aggravates the hemodynamic and inflammatory responses to shock. However, it is unclear whether endogenous opioid activation is triggered by noxious stimuli and furthermore whether it produces analgesia.

METHODS

Experiments were conducted in chronically catheterized, conscious, unrestrained, nonheparinized, male, Sprague-Dawley rats subjected to fixed pressure hemorrhage. Blood samples were obtained for determinations of circulating beta-endorphin and substance P. Analgesia was measured using the tail-flick response to a noxious stimulus before and during hemorrhage. The contribution of sensory neurons to eliciting the neuroendocrine, opioid, and inflammatory responses to hemorrhage was investigated in capsaicin-treated animals.

RESULTS

Hemorrhagic shock produced marked naltrexone-sensitive analgesia without significant modulation of substance P. Peripheral sensory denervation did not alter the hemodynamic, neuroendocrine, or inflammatory responses to shock.

CONCLUSION

Endogenous opioid activation during shock produces analgesia. Sensory neuron activation appears to have limited effect on shock-induced hemodynamic and proinflammatory responses. Furthermore, these results suggest that the activation of neuroendocrine and opioid pathways during shock is not likely to be a response to noxious stimuli.

Differential regulation of cytokines and transcription factors in liver by curcumin following hemorrhage/resuscitation

Inflammatory cytokines interleukin 1 (IL-1), IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha) have been recognized as important mediators of pathophysiological and immunological events associated with shock. These inflammatory events after hemorrhage and resuscitation are characterized by the activation of transcription regulators such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Curcumin, an anti-inflammatory remedy used in Indian medicine, is known to suppress NF-kappaB and AP-1 activation and also to reduce ischemia-reperfusion injuries in animal models. Therefore, the aim of this study was to determine whether administration of curcumin before hemorrhagic shock has any salutary effects on cytokines and the redox-sensitive transcription factors NF-kappaB and AP-1. mRNA levels of IL-1alpha, IL-1beta, IL-2, IL-6, IL-10, and TNF-alpha were determined by reverse transcriptase-polymerase chain reaction in rat livers collected at 2 and 24 h after hemorrhage/resuscitation. The effect of curcumin on the activation of NF-kappaB and AP-1 was determined by electrophoretic mobility shift assays. Significant increases in the levels of liver cytokines IL-1alpha, IL-1beta, IL-2, IL-6, and IL-10 were observed in the 2-h posthemorrhage/resuscitation group compared with sham animals. In contrast, oral administration of curcumin for 7 days followed by hemorrhage/resuscitation regimen resulted in significant restoration of these cytokines to depleted levels, and, in fact, IL-1beta levels were lower than sham levels. Also, the 24-h postresuscitation group showed similar patterns with some exceptions. NF-kappaB and AP-1 were differentially activated at 2 and 24 h posthemorrhage and were inhibited by curcumin pretreatment. Serum aspartate transaminase estimates indicate decreased liver injury in curcumin-pretreated hemorrhage animals. These results suggest that protection against hemorrhage/resuscitation injury by curcumin pretreatment may result from the inactivation of transcription factors involved and regulation of cytokines to beneficial levels.

Anti-inflammatory effect of cholecystokinin and its signal transduction mechanism in endotoxic shock rat

AIM: To study the anti-inflammatory effects of cholecystokinin-octapeptide (CCK-8) on lipopolysaccharide (LPS)-induced endotoxic shock (ES) and further investigate its signal transduction pathways involving p38 mitogen-activated protein kinase (MAPK) and IκB-α.

METHODS: Eighty-four rats were divided randomly into four groups: LPS (8 mg·kg^-1, iv) induced ES; CCK-8 (40 μg·kg^-1, iv) pretreatment 10 min before LPS (8 mg·kg^-1); CCK-8 (40 μg·kg^-1, iv) or normal saline (control) groups. The inflammatory changes of lung and spleen, phagocytic function of alveolar macrophage, quantification of inflammatory cells in bronchoalveolar lavage (BAL) were investigated in rats by using hematoxylin and eosin (HE) staining, phagocytosis of Candida albicans and differential cell counting. Nitric oxide (NO) production in serum, lung and spleen was measured with the Griess reaction. The mechanism involving p38 MAPK and IκB-α signal pathways was investigated by Western blot.

RESULTS: Inflammatory changes of lung and spleen induced by LPS were alleviated by CCK-8, the increase of NO induced by LPS in serum, lung and spleen was significantly inhibited and the neutrophil infiltration in BAL was significantly reduced by CCK-8. The number of neutrophils was (52 ± 10) × 10⁶ cells•L^-1 in LPS group, while it decreased to (18 ± 4) × 10⁶ cells•L^-1 in CCK-8+LPS (P < 0.01). The phagocytic rate of CCK-8 group increased to (62.49 ± 9.49)%, compared with control group (48.16 ± 14.20)%, P < 0.05. The phagocytosis rate was (85.14 ± 4.64)% in LPS group, which reduced to (59.33 ± 3.14)% in CCK-8+LPS group (P < 0.01). The results of phagocytosis indexes showed similar changes. CCK-8 may play an important role in increasing the expression of p38 MAPK and decreasing the degradation of IκB-α in lung and spleen of ES rats.

CONCLUSION: CCK-8 can result in anti-inflammatory effects, which may be related to activation of p38 MAPK and inhibition on the degradation of IκB-α.

Prolonged apneas and hypoxia mediated by nicotine and endotoxin in piglets

OBJECTIVE

Infections and maternal smoking are risk factors for SIDS, and toxins from common bacteria have been proposed as a causative link between infections and SIDS. Nicotine can be transferred in significant amounts postnatally to the infant through environmental tobacco smoke or maternal smoking before nursing. We investigated the acute effects of nicotine and endotoxin on repeated apnea by laryngeal reflex stimulation and the following autoresuscitation.

DESIGN

Thirty-four 1-week-old (+/- 1 day) piglets were sedated and randomized to 1 of 4 pretreatment groups: (1) 1 microg endotoxin i.v./kg; (2) 5 microg nicotine i.v./kg; (3) 1 microg endotoxin i.v./kg and 5 microg nicotine i.v./kg, and (4) placebo. Apnea was induced by insufflation of 0.1 ml of acidified saline (pH 2) in the subglottic space of the trachea three times with intervals of 2 min.

RESULTS

Pretreatment with endotoxin caused a significant increase in plasma TNF-alpha in the endotoxin groups (mean value +/- SEM 953 +/- 246 and 980 +/- 226 pg/ml, respectively) but no significant change in plasma IL-1 beta. Blood pressure, respiratory rate or S(a)O(2) was not significantly affected before induced apnea. Both pretreatment with nicotine and endotoxin caused prolonged apneas by 35-45%, a complete loss of normal hyperventilation during autoresuscitation, and prolonged hypoxia after apnea.

CONCLUSIONS

Nicotine and endotoxin interferes with autoresuscitation after apnea. This experimental model on piglets may shed light over important mechanisms involved in the causation of SIDS.

Impact of alcohol intoxication on hemodynamic, metabolic, and cytokine responses to hemorrhagic shock

BACKGROUND

Alcohol intoxication is associated with a high incidence of traumatic injury, particularly in the young healthy population. The impact of alcohol intoxication on the immediate pathophysiologic response to injury has not been closely examined. We hypothesized that acute alcohol intoxication would aggravate the immediate outcome from hemorrhagic shock by impairing homeostatic counterregulation to blood loss.

METHODS

Chronically catheterized male Sprague-Dawley rats were randomized to receive an intragastric infusion of ethyl alcohol (1.75 g/kg followed by 250-300 mg/kg/h) or isocaloric dextrose (3-mL bolus + 0.375 mL/h) for 15 hours. Before initiating fixed-pressure hemorrhage followed by fluid resuscitation, an additional intragastric bolus of ethyl alcohol (1.75 g/kg) was administered. Hemodynamic, metabolic, cytokine, and acid-base parameters were assessed during the hemorrhage period and at completion of resuscitation. Lungs were obtained for cytokine determinations.

RESULTS

Basal mean arterial pressure was significantly lower in alcohol-intoxicated (blood-alcohol concentration, 135 +/- 12 mg/dL) animals than in controls during baseline (20%) and after the initial fluid resuscitation period (30%). Hemorrhage decreased arterial HCO3 and Pco2, and increased Po2 without significant alteration in arterial blood pH. Alcohol intoxication blunted the decrease in Pco2 and increase in Po2 and decreased blood pH during baseline and throughout the course of the hemorrhage period. Hemorrhage produced marked and progressive elevations in plasma glucose and lactate levels in controls, and this was inhibited by alcohol intoxication. Hemorrhage elevated plasma tumor necrosis factor-alpha (TNF-alpha) (686 +/- 252 pg/mL) and interleukin (IL)-10 (178 +/- 25 pg/mL), and did not alter IL-6 and IL-1 levels. Alcohol blunted the hemorrhage-induced rise in plasma TNF-alpha (142 +/- 48 pg/mL) and enhanced the hemorrhage-induced increase in IL-10 (678 +/- 187 pg/mL). Hemorrhage produced a two- to threefold increase in lung content of TNF-alpha, IL-1alpha, and IL-6 without significantly altering lung IL-10. Alcohol exacerbated the hemorrhage-induced increase in lung TNF-alpha, and did not alter the IL-1alpha, IL-6, and IL-10 lung responses.

CONCLUSION

These results indicate marked alterations in the hemodynamic and metabolic responses to hemorrhagic shock by alcohol intoxication. Furthermore, our findings suggest that alcohol modulates the early proinflammatory responses to hemorrhagic shock. Taken together, these alterations in metabolic and inflammatory responses to hemorrhage are likely to impair immediate outcome and predispose to tissue injury.

Stress-specific opioid modulation of haemodynamic counter-regulation

1. The haemodynamic and cardiovascular responses to stress, in addition to being under control of the autonomic nervous system, are also under opiate modulation. Our studies have provided evidence for activation of the endogenous opioid system in haemorrhagic shock, sepsis and trauma. Furthermore, we have demonstrated that both central and systemic opiate administration to naïve rats result in marked alterations in haemodynamic responses, which are associated with activation of the sympathetic nervous system. 2. Because of the ubiquitous presence of opiate receptors in both the central nervous system and peripheral tissues, as well as their production and release centrally and peripherally, this facilitates an endocrine as well as a paracrine contribution to modulating vascular responses to stress, either directly or indirectly. Results from previous studies suggest that endogenous opioids are not involved in mediating the lipopolysacharide-induced hypotensive response. 3. In more recent studies, we have examined the role of opiate receptor activation in modulating the haemodynamic and neuroendocrine responses to fixed pressure haemorrhagic shock in conscious unrestrained rats. Using systemic opiate blockade (naltrexone, 15 mg/kg, i.p.) prior to haemorrhage, we have observed that blood loss required to achieve mean arterial blood pressure of 40 mmHg was higher in naltrexone-treated animals than in time-matched saline controls. Interestingly, the haemodynamic modulation exerted by naltrexone cannot be attributed to differences in circulating catecholamine levels. Haemorrhage produced an immediate and progressive increase in circulating adrenaline and noradrenaline levels, reaching values that were 50- and 20-fold higher than basal, respectively. Naltrexone pretreatment did not alter the time-course or magnitude of the rise in circulating levels of catecholamines. 4. These results indicate that endogenous opioid activation contributes to the haemodynamic dishomeostasis associated with blood loss. Our findings suggest stress-specific roles for opiate-sensitive haemodynamic counter-regulatory responses.

CCK8 inhibits expression of TNF-α in the spleen of endotoxic shock rats and signal transduction mechanism of p38 MAPK

AIM: To study the effect of sulfated cholecystokinin-octapeptide (CCK-8) on systemic hypotension, gene and protein expression of TNF-α in spleen of lipopolysaccharide (LPS) nduced endotoxic shock (ES) rats, and further investigate the signal transduction mechanism of p38 mitogen-activated protein kinase (MAPK).

METHODS: The changes of blood pressure were observed using physiological record instrument in four groups of rats: LPS (8 mg·kg^{- 1}, iv), CCK-8 (40 μg·kg^-1, iv) pretreatment 10 min before LPS (8 mg·kg^-1), CCK-8 (40 μg·kg^-1, iv) or normal saline (control) group. The content of TNF-α in the spleen was assayed 2 h after LPS administration using ELISA kit and the expression of TNF-α mRNA was examined 30 min, 2 h and 6 h after LPS administration by reverse transcribed polymerase chain reaction (RT-PCR). Activation of p38 MAPK was detected with Western blot 30 min after LPS administration.

RESULTS: CCK-8 reversed LPS-induced decrease of mean arterial pressure ( MAP ) in rats. The content of TNF-α in the spleen was (282 ± 30) ng·L^-1 in control group, while it increased to (941 ± 149) ng·L^-1 in LPS group, P < 0.01. CCK-8 significantly inhibited the LPS-induced increase of TNF-α content in spleen. It decreased to (462 ± 87) ng·L^-1 in CCK-8 + LPS group, P < 0.01. The expression of TNF-α mRNA 30 min and 2 h after treatment was stronger in LPS group, while it was lowered after CCK-8 pretreatment.The p38 MAPK expression increased significantly in LPS group (5.84 times of control) and CCK-8 increased the activation of p38 MAPK in ES rats (10.74 times of control).

CONCLUSION: CCK-8 reverses the decrease of MAP in ES rats and has inhibitory effect on the gene and protein expression of TNF-α in spleen, and p38 MAPK may be involved in its signal transduction mechanisms.

Effect of cholecystokinin on cytokines during endotoxic shock in rats

AIM: To study the effect of cholecystokinin-octapeptide (CCK-8) on systemic hypotension and cytokine production in lipopolysaccharide (LPS)-induced endotoxic shock (ES) rats.

METHODS: The changes of blood pressure were observed using physiological record instrument in four groups of rats: LPS (8 mg•kg¯¹, iv) induced ES; CCK-8 (40 μg•kg¯¹, iv) pretreatment 10 min before LPS (8 mg•kg¯¹); CCK-8 (40 μg•kg¯¹, iv) or normal saline (control) groups. Differences in tissue and circulating specificity of the proinflammatory cytokines (TNF-α, IL-1β and IL-6) were assayed with ELISA kits.

RESULTS: CCK-8 reversed LPS-induced decrease of mean artery blood pressure (MABP) in rats. Compared with control, LPS elevated the serum level of IL-6 significantly (3567 ± 687) ng•L¯¹vs 128 ± 22 ng•L¯¹, P < 0.01), while contents of TNF-αβ elevated significantly (277 ± 86 ng•L¯¹vs not detectable and 43 ± 9 ng•L¯¹vs not detectable, P < 0.01) but less extent than IL-6. CCK-8 significantly inhibited the LPS-induced increase in serum TNF-α, IL-1β and IL-6. LPS elevated spleen and lung content of IL-1β significantly (5184 ± 85 ng•L¯¹vs 1047 ± 21 ng•L¯¹ and 4050 ± 614 ng•L¯¹vs not detectable, P < 0.01), while levels of TNF-α and IL-6 also rose significantly but in less extent than IL-1β. CCK-8 inhibited the LPS-induced increase of the cytokines in spleen and lung. In the heart, CCK-8 significantly inhibited LPS-induced increase of TNF-α (864 ± 123 ng•L¯¹ in CCK-8 + LPS group vs 1599 ± 227 ng•L¯¹ in LPS group, P < 0.01), and IL-1β (282 ± 93 ng•L¯¹ in CCK-8+LPS group vs 621 ± 145 ng•L¯¹ in LPS group, P < 0.01).

CONCLUSION: CCK-8 reverses ES, which may be related to its inhibitory effect on the overproduction of cytokines.

Influence of naloxone on the increased sensitivity to propofol during hypovolemia in the rat

OBJECTIVE

Hypovolemia has been shown to decrease the dose requirement for propofol. This increased effect has been explained partially by an increased end organ sensitivity to the anesthetic effect of propofol. We used the opioid blocking agent naloxone to test the hypothesis that endogenous opioids may be involved in this increased sensitivity.

SUBJECTS

Thirty-two chronically instrumented rats were assigned randomly to either the hypovolemia (n = 16) or the control (n = 16) group.

INTERVENTIONS

After pretreatment of each rat in the two groups with either intravenous saline (n = 8) or naloxone (3 mg/kg; n = 8), an intravenous infusion of propofol (150 mg x kg(-1) x hr(-1)) was given until 5 secs of electrical suppression of the electroencephalographic signal was observed. Return of righting reflex was used to assess depth of anesthesia, and the propofol blood concentration was determined simultaneously with high-performance liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

The mean propofol blood concentrations at the return of righting reflex were significantly lower in the hypovolemic animals compared with the controls within both naloxone-treated (2.1 +/- 0.2 microg/mL vs. 2.9 +/- 0.2 microg/mL; p < .01) and saline-treated (2.2 +/- 0.1 vs. 3.0 +/- 0.2 microg/mL; p < .01) rats. The mean concentrations were not different between the saline- and naloxone-treated rats either within the hypovolemic group or within the control group.

CONCLUSIONS

The results of our study indicate that it is unlikely that the increased end organ sensitivity to propofol during hypovolemia is mediated by endogenous opioids, because it was not reversed by naloxone.

Noradrenergic inhibition of TNF upregulation in hemorrhagic shock

The early stress responses to hemorrhagic shock, trauma and endotoxicosis are associated with an early proinflammatory response characterized by increased gene expression of proinflammatory cytokines, PMN influx and accumulation in the lung and apoptosis. The central role of the neuroendocrine system in modulating these proinflammatory responses has been strongly suggested by recent studies.

OBJECTIVES

To examine the role of noradrenergic innervation in modulating the early increase in lung and spleen content of TNF-alpha in response to fixed-pressure (40 mm Hg) hemorrhage in vivo.

METHODS

Conscious unrestrained nonheparinized male Sprague-Dawley rats (n = 42) were randomized to receive intraperitoneally either 6-hydroxy-dopamine (6-OHDA; chemical sympathectomy, SNSx) or saline (0.3 ml) prior to undergoing hemorrhage followed by fluid resuscitation with lactated Ringer's solution. Animals were sacrificed at completion of the resuscitation period and tissue samples (lung and spleen) excised for determination of TNF-alpha content, myeloperoxidase activity and apoptosis.

RESULTS

Hemorrhage resulted in an immediate marked elevation in circulating epinephrine and norepinephrine levels (10- and 2-fold, respectively), increasing their plasma ratio to 6:1. SNSx depleted tissue stores of norepinephrine (80%), did not alter basal plasma levels of epi- or norepinephrine or the hemorrhage-induced rise in epinephrine, but completely prevented the rise in circulating norepinephrine. Hemorrhage increased lung and spleen contents of TNF-alpha (55 and 72%, respectively). SNSx significantly enhanced the hemorrhage-induced rise in lung TNF in response to hemorrhage.

CONCLUSIONS

These results show a suppressive role for noradrenergic innervation on the hemorrhage-induced increase in tissue TNF-alpha content in vivo. We speculate that the effects of norepinephrine are protective from tissue injury but are likely to contribute to the generalized immunosuppression following trauma.

Endogenous opiates: 1999

This paper is the twenty-second installment of the annual review of research concerning the opiate system. It summarizes papers published during 1999 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunologic responses.