Injection Of Turpentine Research Articles

Time-course study of the Golgi-lysosome region of rat hepatocytes during early acute phase response to inflammation.

In a previous study of the hepatocyte Golgi apparatus 24 hr following the induction of the acute phase response to inflammation, it was found that the predominant secretory content was a granulofilamentous material (GFM), rather than lipoprotein particles (LP) as in controls (Thorne-Tjomsland and Jamieson, 1995, Anat. Rec., 241:439-450). The present study aimed to determine when and how this switch occurs and to monitor the Golgi-lysosome region of hepatocytes in general during early inflammation. Rats were injected with turpentine oil as an inflammatory agent. At 1, 2, 6, 12, and 16 hr after turpentine-injection (TI), the livers were prefixed by perfusion with cacodylate-buffered glutaraldehyde, postfixed with ferrocyanide reduced osmium, and processed for thin section transmission electron microscopy. LP were processed at all time points between 1 and 16 hr post-TI, and at 1 and 2 hr post-TI, the Golgi stacks were engorged with LP and therefore apparently processed more of these particles than in controls. A GFM was processed at later time points, starting at 12 hr post-TI. At the two time points when LP and GFM were co-processed, these materials were frequently seen sorted from each other within the trans-saccule and/or the trans-Golgi network (TGN). At the level of the TGN, these materials were packaged into secretory vesicles which typically contained LP and/or GFM. Massive depletion of cytoplasmic glycogen was observed primarily at 1, 2, and 6 hr following TI. Concomitantly and temporarily, glycogen accumulated within Golgi-associated lysosome-like bodies with extensive appendages. The switch in Golgi apparatus secretory content from LP to GFM occurred at around 12 hr post-TI, but was not discrete. The initial appearance of the GFM coincided with the initial increase in the serum of hepatocyte-derived acute phase reactants (see review Schreiber et al., 1989, Ann. NY Acad. Sci., 557: 61-85). An additional and surprising finding of the present study was that significant changes occurred in the Golgi-lysosome region much prior to the onset of acute phase reactant synthesis: 1 and 2 hr post-TI, the Golgi processed above-normal amounts of LP and Golgi-associated, lysosome-like bodies sequestered glycogen.

Polyacrylamide gel electrophoretic serum protein patterns of acute inflammation induced by intramuscular injection of turpentine in young broiler chickens.

Changes in the serum protein patterns accompanying inflammation in young broilers were examined by polyacrylamide gradient gel electrophoresis. Sera were obtained from blood of 4-week-old male broilers after induction of acute inflammation by an injection of 0.5 ml/kg turpentine. Electrophoretic patterns at 48 hr after injection, showed an increase in transferrin (Tf) and a segment containing albumin (Alb) with multiple peaks. The unbound iron binding capacity (UIBC) increased by 10 times, and the serum iron (SI) concentration in acute inflammation was reduced to one-half its initial value. These are considered to be typical changes in serum proteins and iron after acute inflammation.

Arterial Thrombosis Enhanced by an Acute Phase Response

Induction of an acute phase response causes changes in the levels of specific plasma proteins. Fibrinogen is elevated to approximately twice its normal concentration by trauma, inflammation, or infection. In this study, an acute phase response was induced by subcutaneous turpentine injection in rats. Twenty-four hours later, an arterial model of thrombosis was created bilaterally in the femoral arteries. Patency at 1 and 7 days postoperatively was 24% (9/38) in comparison to 56% (20/36) in control (saline-injected) rats undergoing the same thrombosis model. Fibrinogen levels were elevated in the turpentine group to 5.3 +/- 0.8 mg/ml at the time of the surgery and 7.2 +/- 0.3 mg/ml 24 hours after surgery. In contrast, the control group had plasma fibrinogen levels of 2.5 +/- 0.2 mg/ml at the time of surgery and 5.4 +/- 0.5 mg/ml 24 hours postoperatively. These findings suggest that when an acute phase reaction has been induced several hours prior to a microvascular procedure, there may be an increased risk for development of arterial thrombosis.

Regulation of albumin synthesis after hepatectomy and in the acute inflammation phase of rat liver

Hepatic albumin synthesis is down-regulated after both inflammation and hepatectomy. The transcriptional control of albumin synthesis was investigated in models of both conditions to differentiate the underlying mechanisms. Male Donryu rats underwent 70% hepatectomy or turpentine injection. Serum albumin and mRNA levels of albumin and promoter binding proteins (D site binding protein [DBP] CCAAT/enhancer binding protein-α[ C EBP -α], -β , and hepatocyte nuclear factor-1 [HNF-1]) in the liver were measured from 0 to 96 hr. After hepatectomy, the albumin mRNA level decreased to 0.6 at 36 hr and then recovered. After turpentine injection, it decreased to 0.4 at 36 hr and then recovered. The serum level of albumin decreased in a time-dependent manner in both models. The C EBP -α mRNA level decreased to 0.5 at 6 and 12 hr after hepatectomy and to 0.6 at 24 hr after turpentine injection. The DBP mRNA level decreased to 0.3 at 6 hr, to 0.2 at 24 hr after hepatectomy, and to 0.3 at 30 hr after turpentine injection. The C EBP -β mRNA level increased to 1.7 at 3 hr after hepatectomy and to 1.5 at 12 hr after turpentine injection. On the other hand, HNF-1 mRNA levels showed no consistent change in either model. The change in mRNA of the nuclear factors ( C EBP -α, C EBP -β , and DBP) thus precedes that of albumin. In conclusion, transcriptional regulation of albumin synthesis in the regenerating and the acute inflammation phase of the liver can be assessed by monitoring the mRNA levels of nuclear factors. The mechanisms for down-regulation of albumin in both conditions share substantial similarities.

IL-6 stimulates vitronectin gene expression in vivo.

We tested the hypothesis that vitronectin (Vn) is regulated as an acute phase reactant in response to inflammatory stimuli. In initial experiments, Vn levels were measured during the surgically induced acute phase response in humans. The plasma concentration of Vn increased approximately twofold following elective orthopedic surgery and remained elevated up to 5 days. To examine the mechanism(s) of increased Vn synthesis, hepatic Vn mRNA expression and serum levels were examined in three rat models of acute inflammation: LPS (i.v.), CFA (i.p.), or turpentine (s.c.) injection. The serum concentration of Vn increased approximately twofold 24 h following treatment with turpentine. The expression of Vn mRNA in the liver increased markedly as early as 3 h after treatment in these models and remained elevated up to 18 h. Northern blot analysis of RNA isolated from fractionated liver cells derived from rats treated with LPS indicated that Vn was mainly expressed in hepatocytes, but not in the endothelial or nonparenchymal cell fractions. To analyze the individual effects of raised corticosterone and IL-6 levels on the expression of hepatic Vn mRNA, rats were injected (i.p.) with either dexamethasone or purified recombinant rat IL-6. Vn mRNA expression was elevated within 1 h after IL-6 injection, whereas dexamethasone-injected rats showed unchanged Vn expression. Vn mRNA also was increased in rats chronically injected with IL-6. These results indicate that the Vn gene is up-regulated in acute and chronic inflammation, and this induction is primarily mediated by IL-6.

The major acute phase serum protein in pigs is homologous to human plasma kallikrein sensitive PK-120

A major acute phase protein (pig-MAP) has been isolated from the sera of pigs after turpentine injection. The protein is the pig counterpart of a recently cloned human serum protein denominated PK-120, which is a putative substrate for kallikrein [Nishimura et al., 1995 FEBS Lett. 357, 207–211]. The protein exists in other mammalian species and it is also an acute phase protein, at least in the rat. Pig-MAP shows homology, as PK-120, with the heavy chain 2 (HC-2) of the inter-α-trypsin inhibitor superfamily but does not possess trypsin inhibitory activity.

Identification of a New Acute Phase Protein

We have previously reported mouse SIP24 protein as a secreted inducible protein produced by quiescent Balb/c 3T3 cells. SIP24 can be produced in response to many factors, including serum, basic fibroblast growth factor, prostaglandin F2 alpha, phorbol ester, and dexamethasone. Here we present evidence to show that SIP24 is the product of mouse 24P3 mRNA. The 24P3 cDNA was originally cloned from an SV40-transformed quiescent mouse primary kidney cell culture, and it has been classified as a new member of the lipocalin protein family. We show that the SIP24/24P3 protein and mRNA increase dramatically in mouse serum and liver during the acute phase response induced by turpentine injection. Injection of mice with dexamethasone caused a modest increase of SIP24/24P3 mRNA in the liver. Tissue distribution studies revealed that SIP24/24P3 is mainly expressed in liver during the acute phase response. SIP24/24P3 was also detected in the brain and the uterus. In mouse BNL (Balb/c normal liver) cells, the production of SIP24/24P3 is stimulated by tumor necrosis factor alpha, which is a major regulator of the expression of other acute phase proteins. From its pattern of regulation, we conclude that SIP24/24P3 is a new type 1 acute phase protein.

Nitric‐Oxide‐Mediated Activation of Iron‐Regulatory Protein Controls Hepatic Iron Metabolism During Acute Inflammation

The molecular regulation of intracellular iron metabolism has been studied in the livers of rats undergoing an acute inflammatory reaction following turpentine injection. Treatment induced an increase in the steady-state level of the transferrin receptor (TfR) mRNA, peaking 18 h after treatment and returning to control levels 24 h after treatment, with no change in TfR gene transcription. RNA band-shift assays documented an activation of the cytoplasmic RNA-binding protein called the iron-regulatory protein (IRP), in parallel with a rise in the amount of TfR transcripts. A 2-3-fold increase in the amount of H and L ferritin subunit mRNAs was found 12-18 h after turpentine treatment. Surprisingly, higher accumulation of ferritin mRNAs did not result in appreciable differences in the liver ferritin content. This might be due to the concomitant rise of IRP activity, which is known to prevent ferritin mRNA translation. The absence of significant changes in the total iron and ferritin contents prompted us to investigate the role of nitric oxide (NO), an inflammatory mediator which is also known to modulate the activity of IRP. Northern-blot analysis showed a marked enhancement in the expression of the inducible form of nitric oxide synthase mRNA in turpentine-treated rats. Furthermore, the activation of IRP and the increase of the TfR mRNA content that occur in turpentine-treated rats were abolished by treatment with N5-nitro-L-arginine, a specific nitric oxide synthase inhibitor. The present data suggest that NO-mediated activation of IRP regulates alterations of hepatic iron homeostasis that occur in acute inflammation.

Down-regulation of albumin synthesis in the rat by human recombinant interleukin-1 beta or turpentine and the response to nutrients.

Inflammatory stimuli and provision of nutrients are important factors regulating both total liver protein synthesis and albumin synthesis. The influence of interleukin-1 beta or turpentine injection and a 2-hour infusion of a hypocaloric mixture of glucose and amino acids on the synthesis of total liver protein and albumin was investigated in rats. Total liver protein synthesis was measured by an i.v. flooding dose of L-[2,6(3)H]phenylalanine and albumin synthesis was determined from the labeling of immunoprecipitated albumin and expressed both as a fraction of total liver protein synthesis and as an absolute rate. Interleukin-1 beta or turpentine injection stimulated total liver protein synthesis compared with controls, whereas albumin synthesis, both as a fraction of total liver protein synthesis and as an absolute synthesis rate, decreased. In control animals, the 2-hour i.v. infusion with glucose and amino acids resulted in a significant increase of total liver protein synthesis. Albumin synthesis as a fraction of total liver protein synthesis was not altered, but increased when expressed as an absolute rate in control animals. However, interleukin-1 beta or turpentine injection abolished this response of albumin synthesis to nutrient supply. Total liver protein synthesis increases under inflammatory conditions and remains responsive to nutrient supply. In contrast, albumin synthesis decreases under the same conditions and does not seem to be responsive to short-term i.v. nutrients.

Role of lipopolysaccharide (LPS), interleukin-1, interleukin-6, tumor necrosis factor, and dexamethasone in regulation of LPS-binding protein expression in normal hepatocytes and hepatocytes from LPS-treated rats

Lipopolysaccharide (LPS)-binding protein (LBP) has been reported to be an acute-phase protein. LBP binds to LPS with a high affinity; LPS-LBP complexes then interact with the receptor CD14, resulting in increased expression of LPS-inducible genes. Hepatocytes represent a major source of LBP, but little is known about the regulation of rodent hepatocyte LBP synthesis. In these studies, undertaken to characterize hepatocyte LBP expression, we show that greater-than-20-fold increases in LBP mRNA levels in hepatocytes occurred following injection of LPS or turpentine in rats. In primary cultures of rat hepatocytes, the addition of interleukin-6 (IL-6) and LPS led to 4.5- and 3.2-fold stimulation in LBP mRNA levels, respectively. The induction of LBP by IL-6 or LPS was attenuated by dexamethasone. In contrast to IL-6 and LPS, in the presence of 10(-6) M dexamethasone, IL-1 and tumor necrosis factor (TNF) led to maximal LBP mRNA induction levels, 4.7- and 3.8-fold, respectively, suggesting that IL-6 and LPS stimulate LBP expression by mechanisms different from those of IL-1 and TNF. Similar induction levels of LBP mRNA were seen in rat H35 hepatoma cells for all four stimuli, and dexamethasone inhibited these responses. Dexamethasone alone increased the spontaneous induction in primary hepatocytes at early time points but suppressed induction at later time points. Furthermore, hepatocytes from rats treated with LPS in vivo exhibited a > 10-fold increase in mRNA expression in response to LPS and enhanced responses to TNF and IL-1. As with the normal hepatocytes, dexamethasone inhibited the LPS-dependent induction in the LPS-treated rat hepatocytes. These data suggest that LBP synthesis by hepatocytes is under the control of LPS, IL-1, TNF, IL-6, and glucocorticoids and that the LPS treatment primes hepatocytes for subsequent responses to LPS, TNF, and IL-1 for LBP synthesis.

Polyacrylamide Gel Electrophoretic Patterns of Chicken Serum in Acute Inflammation Induced by Intramuscular Injection of Turpentine

To develop a method to detect hidden inflammation using serum protein in chickens, changes in serum proteins with acute inflammation were analyzed using a turpentine-induced inflammation model. Inflammation in the pectoral muscle of a 14-wk-old White Leghorn became apparent 3 h after the injection of turpentine and became more severe thereafter. Coincident with the development of inflammation, changes in serum proteins were analyzed by electrophoresis on polyacrylamide gradient gels. The electrophoretic patterns were divided into 21 segments. Two of these segments increased remarkably. These were located near the center of the electrophoretic pattern and were identified as transferrin due to iron staining, correlation of movement against a commercial transferrin sample in SDS-PAGE, and immunoblotting. These results suggest that transferrin may serve as a marker for inflammation in chicken.

Increase in antilipoperoxidant activity of plasma as a consequence of an inflammatory reaction induced by subcutaneous turpentine in the rabbit.

In the rabbit, an acute inflammatory reaction triggered by the subcutaneous administration of turpentine induces in hepatic tissues an oxidative stress, as well as a decrease in activity of enzymatic scavengers of reactive oxygen species (ROS). The objective of this study was to investigate, the repercussions of a local inflammatory reaction on the antioxidant capacity and markers of systemic oxidative stress in plasma. To this purpose, rabbits received a.s.c. injection of turpentine (5 mL/kg) or NaCl 0.9% (w/v). Blood samples were collected at different times during the 48 hours of the experiment to evaluate: firstly, the antilipoperoxidant activity of plasma by measuring the inhibition of autoxidation of brain homogenate, and the concentrations of tocopherol and ascorbic acid; secondly, the severity of oxidative stress in plasma by assaying the concentration of thiobarbituric acid reactive substances (TBARS), and the concentration of ascorbyl radical. The results show that the antilipoperoxidant capacity of plasma gradually increased to be 167% higher than baseline values (p < 0.05) after 48 hours of experiment. alpha-Tocopherol and ascorbic acid levels increased by 49% and 80%, respectively (p < 0.05) during the first 24 hours. Lipid peroxidation continuously increased to be 98% higher than baseline values (p < 0.05) at 48 hours, while ascorbyl radical levels were not modified (p < 0.05). In summary, an acute local inflammatory reaction causes a steady progression of oxidative stress, while it stimulates the antilipoperoxidant activity of plasma, to which alpha-tocopherol and ascorbic acid appear to contribute, essentially early in the inflammation.

The effect of enteral glutamine deprivation and supplementation on the structure of rat small-intestine mucosa during a systemic injury response.

An aseptic model of tissue injury (the induction of abscesses by subcutaneous injections of turpentine) was used to examine the proposal that changes in glutamine metabolism lead to structural damage in the epithelium of the small intestine during the systemic response to injury and to investigate the role of dietary glutamine in the maintenance of mucosal structure in the small intestine of control and injured rats. Glutamine-free and glutamine-rich (3.6% glutamine by weight) diets were fed to rats before and during an acute-phase response to injury. Pair-fed groups of animals enabled an independent assessment to be made of the effects of the associated dietary restriction on the mucosal epithelium. Adaptive increases in villus height and crypt depth were seen in response to 4 days of feeding of the glutamine diet. Pair-feeding (30% dietary restriction) of either diet induced mucosal atrophy (loss of wet weight and nitrogen) without changes in villus height or crypt depth in the proximal tercile of the small intestine. Systemic injury, however, had no effect on the weight or nitrogen content of the mucosa (relative to pair-feeding). Gross histologic appearance, villus height, and crypt depth were also unchanged by the response to injury. The study provided no evidence to support the proposal that alterations in the availability of dietary glutamine during systemic injury (induced by turpentine injections) lead to structural damage to the epithelium.

Tumor necrosis factor-alpha and fever after peripheral inflammation in the rat

The involvement of endogenous tumor necrosis factor-alpha (TNF-alpha) in the pyrogenic [i.e., rise in colonic temperature (Tc)] and thermogenic [increase in oxygen consumption (VO2)] responses to inflammation was investigated in rats subjected to an intramuscular injection of turpentine. Turpentine administration caused a rise in Tc and VO2 within 2 h (0.9 +/- 0.1 degrees C, 27 +/- 2%, respectively). Eighteen to twenty hours after turpentine, the magnitude of these responses had increased (2.3 degrees C fever and a 28% increase in metabolic rate compared with control animals) and was associated with marked inflammation in the injected limb. A rapid (by 4 h) and sustained rise in the plasma concentration of the endogenous pyrogen IL-6, but not TNF-alpha, was also observed. Intravenous pretreatment with a TNF-alpha antiserum attenuated the rise in Tc observed 2, 8, and 18 h after turpentine injection and almost abolished the hypermetabolic response observed at 18 h. In addition, the TNF-alpha antiserum inhibited the peak rise (8 h) in plasma IL-6 by 76%. These findings indicate that endogenous TNF-alpha is involved in fever and hypermetabolism during inflammation and that it may exert these effects by inducing the release of IL-6 into circulation.

Effect of dietary restriction on the response of alpha 2-macroglobulin during an acute phase response.

The effects of aseptic abscesses induced by subcutaneous injections of turpentine (5 mL/kg body weight) on the acute-phase protein response (alpha 2-macroglobulin, alpha 2-M) and on the circulating albumin and total protein concentrations were assessed in young rats that were made malnourished by restricting dietary intake to an extent that either impaired growth (60% of normal intake) or caused weight loss (0% to 45% of normal intake). The measurements were obtained daily during a period of 4 days in malnourished rats that had lost about 25% body weight but had maintained a stable weight thereafter, or in rats that had lost about 12% body weight and were continuing to lose weight at various rates at the time of the turpentine injection. In animals that were injected while they maintained a stable weight after losing about 25% body weight, the alpha 2-M response was attenuated fourfold to eightfold compared with control animals (the area under the 4-day alpha 2-M curve in control rats was 23.3 +/- 2.3 g/L/d). In the depleted animals that were injected while they were actively losing weight (approximately 12.5% weight loss), the attenuation of the alpha 2-M response was related to the rate of weight loss or to the extent of dietary restriction (area under the 4-day alpha 2-M curve ranged from 5.7 +/- 1.4 g/L/d in animals receiving 15% restricted diet to 15.6 +/- 1.5 g/L/d in animals receiving the 45% restricted diet).(ABSTRACT TRUNCATED AT 250 WORDS)

Defective inflammatory response in interleukin 6-deficient mice.

Systemic and localized inflammation elicit a number of host responses which include fever, cachexia, hypoglycemia, and major changes in the concentration of liver plasma proteins. Interleukin 6 (IL-6) is considered an important mediator of the inflammatory response, together with IL-1 and tumor necrosis factor alpha (TNF-alpha). The purpose of this study was to unequivocally determine the role of IL-6 in these phenomena making use of IL-6-deficient mice that we have recently generated by gene targeting. We report here that in the absence of IL-6, mice are unable to mount a normal inflammatory response to localized tissue damage generated by turpentine injection. The induction of acute phase proteins is dramatically reduced, mice do not lose body weight and only suffer from mild anorexia and hypoglycemia. In contrast, when systemic inflammation is elicited through the injection of bacterial lipopolysaccharide (LPS), these parameters are altered to the same extent both in wild-type and IL-6-deficient mice, demonstrating that under these conditions IL-6 function is dispensable. Moreover, we show that LPS-treated IL-6-deficient mice produce three times more TNF-alpha than wild-type controls, suggesting that increased TNF-alpha production might be one of the compensatory mechanisms through which a normal response to LPS is achieved in the absence of IL-6. We also show that corticosterone is normally induced in IL-6-deficient mice, demonstrating that IL-6 is not required for the activation of the hypothalamic-pituitary-adrenal axis. Our results reinforce the idea that different patterns of cytokines are involved in systemic and localized tissue damage, and identify IL-6 as an essential mediator of the inflammatory response to localized inflammation.

Increased Expression of mRNA for Hepatocyte Growth Factor-like Protein during Liver Regeneration and Inflammation

To assess potential roles of hepatocyte growth factor-like (HGFL) protein as a growth factor and as a cytokine, we determined the expression of mRNA for (HGFL) protein during liver regeneration and inflammation. Expression of mRNA for HGFL protein in the regenerating liver was upregulated to 93% and 64% above controls at 1 h following partial hepatectomy and carbon tetrachloride treatment of rats, respectively. Similarly, rat liver mRNA for HGFL protein was upregulated to 78% above controls at 24 h after injection of thioglycollate (inducing activation of peritoneal macrophages) and to 118% at 48 h after injection of turpentine (inducing the acute phase response). These results support a potential role for HGFL protein in the early phase of liver regeneration and as an inflammatory mediator.

The in-vitro uptake of zinc by blood cells in rats with long-term inflammatory stress

The aim of the present study was to investigate the in vitro uptake of zinc by blood cells, in an attempt to distinguish between those conditions in which low plasma zinc concentrations are due to inflammatory stress, and those which are due to true zinc deficiency. Inflammation induced by intramuscular injection of turpentine caused a significant reduction in plasma albumin concentrations, which persisted until the end of the study (2 weeks). It also caused a reduction in the plasma zinc concentration which was most marked during the first few days. A smaller difference persisted until the end of the study. When the serum zinc concentration was corrected for the hypoalbuminaemia, the changes in serum zinc concentration after the first 4 days of turpentine were small and mainly non-significant. The in vitro uptake of zinc by erythrocytes obtained from animals with inflammation did not increase, whereas the uptake was increased in cells obtained from animals with true zinc deficiency. Therefore this study suggests a method that can probably differentiate between an apparent zinc deficiency due to inflammatory stress and a real zinc deficiency, but additional experiments to validate this method should be performed.

Remote Tissue Injury Primes Hepatocytes for Nitric Oxide Synthesis

Following trauma and tissue injury, patients frequently suffer infections and septic complications. Tissue injury is associated with the induction of the hepatic acute-phase response, but how this phenotypic expression by hepatocytes influences their subsequent response to endotoxin (lipopolysaccharide, LPS) or inflammatory cytokines is unknown. We have shown that both rat and human hepatocytes maximally express the enzyme-inducible nitric oxide synthase (iNOS) in response to a combination of LPS and the cytokines tumor necrosis factor (TNF), interferon-γ (IFN-γ), and interleukin-1. Furthermore, we have shown that the in vivo induction of the acute-phase response following tissue injury (hind limb turpentine injection) is not associated with hepatocyte iNOS expression. In this study, we show that the phenotypic change associated with the acute-phase response following tissue injury primes the hepatocyte to subsequently express iNOS in vitro in response to LPS alone as well as TNF and IFN-γ. This expression of iNOS can be seen as early as 3 hr following the initial injury and lasts up to 24 hr. Early postinjury changes result in maximal expression following stimulation with TNF or IFN-γ. Later (24 hr postinjury) changes reveal LPS to be the most potent inducer with as little as 0.01 μg/ml LPS being required for iNOS mRNA expression. The in vivo correlate of tissue injury (turpentine injection) followed by sepsis (intraperitoneal LPS injection) resulted in a three- to fourfold rise in plasma levels of the stable endproducts of nitric oxide production, nitrite, and nitrate (NO-2 + NO-3), over levels seen in cases of sepsis alone. These data show that hepatocytes can be primed by remote tissue injury to respond directly to LPS as well as TNF and IFN-γ. Such enhanced responses could have important influences on hepatocellular function following trauma and sepsis.

Upregulation of Escherichia coli heat-stable enterotoxin receptor in regenerating rat liver

Guanylate cyclase C (GC-C) is a transmembrane protein that serves as a receptor for the recently characterized endogenous ligand guanylin and for Escherichia coli heat-stable toxin (STa). Binding of either guanylin or STa to intestinal GC-C results in net chloride secretion. Although GC-C is expressed in the rat intestine throughout life, its expression in the rat liver has previously been shown to occur only during the perinatal period. As a step toward elucidating the role of this receptor in the liver, we tested the hypothesis that GC-C mRNA expression could be induced in the adult rat liver following 1) partial hepatectomy, a stimulus for hepatocyte proliferation; 2) intraperitoneal carbon tetrachloride injection, a model of hepatocyte regeneration in the presence of inflammatory changes; and 3) subcutaneous turpentine injection, which generates an acute phase response without hepatocyte proliferation. We demonstrated expression of GC-C mRNA in the regenerating rat liver following either partial hepatectomy or CCl4-induced hepatic necrosis. We have also shown that GC-C mRNA expression occurred in association with an acute phase reaction. Coordinate with the expression of GC-C mRNA, there was upregulation of radiolabeled STa binding to liver plasma membranes prepared from turpentine-treated rats. Maximal expression of GC-C occurred in preparations enriched for the canalicular domain. Although the function of GC-C in the liver is unknown, localization to the canalicular domain would be consistent with a role for GC-C in hepatic chloride secretion, especially in the perinatal liver and during hepatocyte regeneration.