Showing papers on "Intraperitoneal injection published in 1993"

Interleukin 10 protects mice from lethal endotoxemia

Abstract: Interleukin 10 (IL-10) decreases production of IL-1, IL-6, and tumor necrosis factor alpha (TNF-alpha) in vitro, and neutralization of IL-10 in mice leads to elevation of the same monokines. We test here whether this monokine-suppressing property of IL-10 confers on it the capacity to protect mice from lipopolysaccharide-induced shock, a monokine-mediated inflammatory reaction. A single injection of 0.5-1 microgram of recombinant murine IL-10 reproducibly protected BALB/c mice from a lethal intraperitoneal injection of endotoxin. This result was obtained whether the IL-10 was administered concurrently with, or 30 min after the injection of endotoxin. The protective effect of IL-10 was reversed by prior injection of neutralizing anti-IL-10 antibodies, and correlated with a substantial decrease in endotoxin-induced TNF-alpha release. These data implicate IL-10 as a candidate for treatment of bacterial sepsis, and more generally as an effective antiinflammatory reagent.

Long-term reversal of diabetes by the injection of immunoprotected islets

Abstract: The intraperitoneal injection of insulin-producing islets immunoprotected by an alginate-poly(amino acid) membrane is a potential method of reversing diabetes without the need for lifelong immunosuppression. Previous attempts to demonstrate this technology in large animals have failed, preventing application in humans. We have determined that key factors responsible for these past failures include cytokine (interleukins 1 and 6 and tumor necrosis factor) stimulation by mannuronic acid monomers from alginate capsules with weak mechanical integrity, which results in fibroblast proliferation. With this insight, we formulated mechanically stable microcapsules by using alginate high in guluronic acid content and report prolonged reversal of diabetes in the spontaneous diabetic dog model by the intraperitoneal injection of encapsulated canine islet allografts. Euglycemia, independent of any exogenous insulin requirement, was noted for up to 172 days. Graft survival, evidenced by positive C-peptide release, was noted for as long as 726 days in a recipient receiving a single injection of immunoprotected islets. Histological evidence of viable islets retrieved from the peritoneal cavity 6 months posttransplant confirmed the biocompatibility and immunoprotective nature of this capsule formulation. The finding that intraperitoneal injection of alginate-immunoprotected islets, a minimally invasive surgical procedure, is effective in prolonged (> 1 year) maintenance of glycemic control, without the need for lifelong immunosuppression, may have significant implications for the future therapy of type I diabetes in humans.

Protein phosphatase inhibition and in vivo hepatotoxicity of microcystins.

Abstract: Administration of microcystin (MCYST)-YM or -LR (peptide hepatotoxins produced by the cyanobacterium Microcystis aeruginosa) to mice resulted in the inhibition of liver protein phosphatase 1 and 2A activity. In all cases significant inhibition preceded or accompanied clinical changes due to MCYST intoxication. Fifteen minutes after intraperitoneal injection of lethal doses of MCYST-YM protein phosphatase activity was already decreased to 44% of controls, and by 60 min was further decreased to 22% of controls. The inhibition was dose dependent: intraperitoneal injection with 84 nmol/kg of MCYST-YM and 48 nmol/kg of MCYST-LR were the minimum doses required for significant inhibition at 60 min. Pretreatment of mice with 200 mumol/kg of rifamycin prevented the inhibition of liver protein phosphatase. The inhibition was tissue specific, with none detected in the kidneys, an organ that, unlike the liver, does not accumulate MCYST. In contrast to MCYST intoxication, lethal doses of phalloidin, a peptide hepatotoxin that produces clinical and pathological changes similar to MCYST, did not cause any inhibition of protein phosphatases.

Neutralization of gamma interferon and tumor necrosis factor alpha blocks in vivo synthesis of nitrogen oxides from L-arginine and protection against Francisella tularensis infection in Mycobacterium bovis BCG-treated mice.

Abstract: Peritoneal cells from Mycobacterium bovis BCG-infected C3H/HeN mice produced nitrite (NO2-, an oxidative end product of nitric oxide [NO] synthesis) and inhibited the growth of Francisella tularensis, a facultative intracellular bacterium. Both NO2- production and inhibition of bacterial growth were suppressed by NG-monomethyl-L-arginine, a substrate inhibitor of nitrogen oxidation of L-arginine, and monoclonal antibodies (MAbs) to gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha). Intraperitoneal injection of mice with BCG increased urinary nitrate (NO3-) excretion coincident with development of activated macrophages capable of secreting nitrogen oxides and inhibiting F. tularensis growth in vitro. Eight days after BCG inoculation, mice survived a normally lethal intraperitoneal challenge with F. tularensis. Treatment of these BCG-infected mice with MAbs to IFN-gamma or TNF-alpha at the time of BCG inoculation reduced urinary NO3- levels to those found in normal uninfected mice for up to 14 days. The same anticytokine antibody treatment abolished BCG-mediated protection against F. tularensis: mice died within 4 to 6 days. Intraperitoneal administration of anti-IFN-gamma or anti-TNF-alpha antibody 8 days after BCG infection also reduced urinary NO3- and abolished protection against F. tularensis. Isotype control (immunoglobulin G) or anti-interleukin 4 MAbs had little effect on these parameters at any time of treatment. IFN-gamma and TNF-alpha were clearly involved in the regulation of macrophage activation by BCG in vivo. Protection against F. tularensis challenge by BCG depended upon the physiological generation of reactive nitrogen oxides induced by these cytokines.

Influence of histamine depletion on learning and memory recollection in rats.

Abstract: To clarify the role of endogenous histamine in learning and memory, the effect of α-fluoromethylhistidine on active avoidance response in rats was studied. α-Fluoromethylhistidine (20–100 mg/kg or 10–50 µg) significantly (P<0.05 orP<0.01) prolonged the response latency in active avoidance response when administered by either intraperitoneal or intracerebroventricular injection. These effects were dose-related and long lasting. A prolongation of the response latency induced by an intraperitoneal injection of α-fluoromethylhistidine (100 mg/kg) was antagonized by intracerebroventricular injection of histamine (10 and 20 ng) in a dose-dependent manner. In addition, the acquisition of this response was retarded by a consecutive intracerebroventricular injection of α-fluoromethylhistidine (50 µg), whereas histamine (100 ng) facilitated the response acquisition when administered by the same route. Both intraperitoneal (100 mg/kg) and intracerebroventricular injection of α-fluoromethylhistidine (50 µg) significantly (P<0.05 orP<0.01) decreased the brain histamine content, especially in the hippocampus and hypothalamus. When α-fluoromethylhistidine (50 µg) was injected intracerebroventricularly, there is a high correlation between a prolongation of the response latency and a decrease in histamine content of these brain areas. Based on these findings, it was concluded that an intimate relation may exist between a prolongation of response latency in the active avoidance response and a decrease in the brain histamine content; endogenous histamine may play an important role in learning and memory recollection in rats.

Glucocorticoid-and non-glucocorticoid induction of lipocortins (annexins) 1 and 2 in rat peritoneal leucocytes in vivo.

Abstract: 1. We have studied the occurrence, distribution and disposition of lipocortins (annexins) 1, 2 and 5 in mixed peritoneal leucocytes obtained from rats in which glucocorticoid levels were altered by adrenalectomy, administration of the glucocorticoid antagonist, RU486, or by injection of dexamethasone or hydrocortisone, as well as from rats in which the peritoneal cells were elicited by inflammatory stimuli. 2. In cells obtained from untreated rats with an intact adrenal cortex, lipocortins 1, 2 and 5 were readily detectable: the majority of each of the proteins was apparently located intracellularly with much smaller amounts in the membrane. Lipocortin 1 and to a lesser extent lipocortin 5 were also seen in a Ca(2+)-dependent association with the external plasma membrane. Following administration of RU486 (2 x 20 mg kg-1) the amounts of lipocortin 1 and 2 in cells were greatly reduced. Conversely, injection of hydrocortisone (1 mg kg-1) or dexamethasone (0.08 mg kg-1) caused an increase in the amount of lipocortin 1 and 2 in peritoneal cells within 30 min. Lipocortin 5 was unchanged by any manipulation of glucocorticoid levels. 3. Lipocortins 1 and 2 were elevated in both intracellular and membrane-associated fractions of macrophages elicited by intraperitoneal injection in inflammogens. This phenomenon also occurred in adrenalectomized animals. 4. Our data indicate that glucocorticoids control the synthesis of some members of the lipocortin family in rat mixed peritoneal cells but also suggest the existence of a separate system for controlling the generation of this protein. The significance of these observations is considered in relation to the mechanism of glucocorticoid hormone action on eicosanoid production.

Monoclonal antibody against CD11b/CD18 inhibits endotoxin-induced uveitis.

Abstract: PURPOSE To examine the serial expression of cell adhesion molecules in C3H/HeN mice with endotoxin-induced uveitis, and to study the effect of treatment with a monoclonal antibody against Mac-1 on the development of endotoxin-induced uveitis. METHODS Immunohistochemical staining was used to document the serial expression of Mac-1, intercellular adhesion molecule-1 (ICAM-1), and lymphocyte function-associated antigen-1 (LFA-1) in eyes of C3H/HeN mice with endotoxin-induced uveitis. Then, in two separate experiments, endotoxin-induced uveitis was produced in a total of 48 mice by injecting Salmonella typhimurium endotoxin into one hind footpad. At the time of endotoxin injection, 24 mice received an intraperitoneal injection of anti-Mac-1 antibody and 24 control mice received an intraperitoneal injection of rat IgG. Histopathologic sections of eyes taken 24 hours after endotoxin injection were graded by two masked observers on a scale of 0 to 4. RESULTS Intercellular adhesion molecule-1 was first expressed on the ciliary body epithelium 6 hr after endotoxin injection and Mac-1 and LFA-1 were expressed on infiltrating inflammatory cells 12 hr after endotoxin injection. Treatment with anti-MAC-1 antibody significantly inhibited the development of ocular inflammation when compared with treatment with control IgG (P < 0.001). CONCLUSION Intercellular adhesion molecule-1 is expressed in the eye before clinical or histologic signs of inflammation. Furthermore, treatment with antibody against Mac-1 significantly inhibits the development of endotoxin-induced uveitis in mice and suggests that anti-Mac-1 antibody may be useful for treating acute ocular inflammation.

The immunosuppressive effects of dexamethasone administered in drinking water to C57BL/6N mice infected with Cryptosporidium parvum.

Abstract: The feasibility of immunosuppressing adult C57BL/6N mice by using dexamethasone in drinking water to sustain infections with Cryptosporidium parvum was investigated. An ethanol-soluble formulation of dexamethasone (DEX) was compared with a water-soluble (phosphated) formulation (DEXp). DEX or DEXp was provided for mice ad libitum in drinking water at dosages of 10, 33, and 100 micrograms/ml. DEX was also administered to mice by intraperitoneal injection at 125 micrograms/mouse/day. All mice were inoculated intragastrically with 10(6) C. parvum oocysts/mouse on day 14 postimmunosuppression. Mice immunosuppressed through drinking water exhibited increased signs of toxicity compared with mice intraperitoneally injected with DEX. Moreover, mice receiving DEX in drinking water were less active and died significantly sooner (P < 0.05) than mice receiving DEXp at the same dosages. Immunosuppressed mice began shedding oocysts 3 days postinfection and continued to shed until they either died or were killed. Beginning on day 12 postinfection, mice receiving DEX or DEXp in drinking water shed significantly more oocysts (P < 0.05) than mice immunosuppressed via intraperitoneal injection. Immunosuppressing mice through drinking water was comparatively simple, less traumatic than injection, and efficient with regard to time and labor.

Induction Of Donor-specific Tolerance To Cardiac But Not Skin Or Renal Allografts By Intrathymic Injection Of Splenocyte Alloantigen

Abstract: We have recently found that donor-specific tolerance to a cardiac allograft can be achieved after the intrathymic (i.t.) injection of donor splenocytes and a single intraperitoneal injection of rabbit antirat lymphocyte serum. The present study evaluated whether the tolerance induced by splenocytes injected i.t. could also prevent the rejection of kidney and skin allografts. Male Buffalo (RT1b) rats were given 25 x 10(6) fully MHC-mismatched unfractionated Lewis (RT1l) splenocytes by i.t. injection plus 1 ml of ALS i.p. and 21 days later underwent a Lewis heterotopic cardiac, orthotopic renal, or skin transplant. Lewis i.t. injection induced a donor-specific tolerance with indefinite cardiac allograft survival (> 153.1 days) in 88% of the recipients without the need for further immunosuppression, while renal and skin allograft survival was prolonged (kidney 14.8 days vs. control 7.8 days; skin 11.6 days vs. control 9.2 days) but were still rejected. Buffalo recipients with a long-surviving Lewis cardiac allograft after Lewis i.t. injection were still able to reject a third-party heterotopic ACI (RT1a) cardiac allograft in normal time (7.0 days), but did not reject a second Lewis cardiac allograft (> 100.0 days). In contrast, however, Buffalo recipients with long-surviving Lewis cardiac allografts did reject a Lewis skin allograft in normal time (10.0 days) and a Lewis renal allograft in a prolonged manner (17.6 days) without causing the rejection of the Lewis cardiac allografts. These data support the important role tissue-specific non-MHC antigens may play in the rejection of kidney and skin allografts.

Changes in serotonin metabolism may elicit obstructive apnoea in the newborn rat.

Abstract: 1. Experiments were performed on anaesthetized newborn rats (aged 3-10 days) to know whether an increase in central serotonin levels might favour the occurrence of obstructive apnoeas as previously suggested by in vitro results from our group. 2. The levels of serotonin (5-HT), its precursor 5-hydroxytryptophan (5-HTP) and its metabolite, 5-hydroxyindole-acetic acid (5-HIAA), were analysed in cerebrospinal fluid samples collected at the level of the obex prior to and after intraperitoneal injection of L-tryptophan (50 mg kg-1) in sixty-eight anaesthetized newborn rats (control rats prior to injection and injected rats 15, 30 and 45 min after the injection). A significant increase in 5-HT and 5-HTP levels occurred 30 min after the injection, attesting to the activation of 5-HT biosynthesis. 3. The EMG activity of both the genioglossus and the diaphragm was recorded before and after L-tryptophan load (50 mg kg-1) in twenty-two newborn rats. After the injection of L-tryptophan, the amplitude of the integrated genioglossus activity decreased, or was even abolished, either during a few respiratory cycles or for long periods in twenty-one out of twenty-two animals. Recovery of the genioglossus activity occurred within 45-60 min. 4. The thoracic respiratory movements and the resulting upper airway pressure changes were recorded before and after L-tryptophan injection (50 mg kg-1) in sixty-two animals. In some litters (n = 7), most of the animals (21/25) displayed, within 20-40 min of the injection, recurrent episodes of obstructive apnoea often followed by central ones. These respiratory difficulties became severe and drastic, and led in two instances to respiratory distress and death. Lower doses of L-tryptophan (10 mg kg-1) did not induce any respiratory disorders unless these were potentiated by pargyline treatment (50 mg kg-1, n = 7). The obstructive apnoeas liable to occur after an L-tryptophan load (50 mg kg-1) were prevented by blocking the 5-HT receptor with methysergide (50 mg kg-1, n = 5) or by blocking the 5-HT biosynthesis by applying p-chlorophenylalanine (PCPA) pretreatment at birth (300 mg kg-1, n = 7). In other litters (n = 6), none of the eighteen newborn rats tested were affected by L-tryptophan, however, In five young adult rats, L-tryptophan again had no effect.4+ ĕ

Central interferon-alpha inhibits natural killer cytotoxicity through sympathetic innervation

Abstract: The brain has been known to produce high levels of interferon-alpha (IFN-alpha) during viral infections. We investigated the central and peripheral mechanisms of the brain IFN-alpha-induced suppression of natural killer (NK) cytotoxicity in the rat. The activity of NK cells in the spleen and the peripheral blood decreased 30-120 min after intracerebroventricular (icv) injection of recombinant human IFN-alpha of > 1,000 U but not after its intraperitoneal injection. This effect was antagonized by pretreatment with icv naltrexone (NLTX). Splenic denervation was observed to completely abolish the IFN-alpha-induced suppression of NK activity, whereas bilateral adrenalectomy did not. Furthermore, this immunosuppression was blocked by an icv injection of an antagonist of corticotropin-releasing factor (CRF), alpha-helical CRF-(9-41). The icv injection of CRF resulted in reduced NK activity, which was not affected by NLTX. The results suggest that brain IFN-alpha activates the CRF system through central opioid receptors and thereby suppresses the NK cytotoxicity predominantly through splenic sympathetic innervation.

Prevention of High- and Low-Dose STZ-Induced Diabetes With D-Glucose and 5-Thio-D-Glucose

Abstract: To induce hyperglycemia in mice by administration of STZ, two experimental protocols that involve different pathogenic pathways are being used. First, the intraperitoneal injection of a single high dose (HD-STZ) exerts direct toxicity on beta-cells, which results in necrosis within 48-72 h and overt permanent hyperglycemia. Second, injections of multiple low doses of STZ (LD-STZ), administered intraperitoneally on 5 consecutive days, induce both beta-cytotoxic effects and STZ-specific T-cell-dependent immune reactions. In LD-STZ models, only a combination of toxic and immunological effects result in gradually increasing hyperglycemia, provided male mice of susceptible strains are being used. In this study, we found that 5-T-G, a glucose analogue that has sulfur for oxygen in the pyranose ring, prevented, in a dose-dependent way, both HD-STZ- and LD-STZ-induced hyperglycemia and that D-G, which was only tested in the LD-STZ system, was also protective, albeit somewhat less so than 5-T-G. This protective effect was achieved by intraperitoneally injecting 5-T-G and D-G, respectively, right before each STZ injection. Protection against hyperglycemia was already achieved with a total of 3 injections of 5-T-G, 1 injection each given before the first 3 of 5 LD-STZ injections. By means of OGTT, it was determined that pretreatment with 5-T-G afforded protection from substantial beta-cell damage in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicity of Withania Somnifera Root Extract in Rats and Mice

Abstract: Alcohol Extracts From The Roots Of W. Somnifera (‘Ashwaganda’ In Sanskrit) Were Screened For Their Acute (24 H) Toxicity In Conventional Swiss Albino Mice and Subacute Toxicity (30 Days) In Wistar Rats. A Single Intraperitoneal Injection Of 1100 Mg/Kg Of The Extract In Mice Did Not Produce Any Deaths Within 24 H, But Small Increases Led To Mortality. The Ld50 Value Was Calculated As 1260 Mg/Kg Body Wt. Subacute Toxicity Studies With Repeated Injections Of Ashwagandha Extract At A Dose Of 100 Mg/Kg Body Wt. (= 1/12 Ld50) For 30 Days In Wistar Rats Of Either Sex Did Not Result In Any Mortality Or Changes In Peripheral Blood Constituents. However, Significant Reductions In The Weights Of Spleen, Thymus and Adrenals Were Observed In Male Rats At The End Of The Experiment. The Acid Phosphatase Content Of Peripheral Blood In Both Sexes Showed A Significant Increase From Control, While Other Biochemical Parameters Determined In The Study Were In The Normal Range.

Polyethylene glycol-conjugated superoxide dismutase protects rats against oxygen toxicity.

Abstract: Superoxide dismutase (SOD) has an important role in the protection against O2 toxicity. Conjugation of Cu,Zn-SOD to polyethylene glycol (PEG-SOD) prolongs its plasma half-life and facilitates its cellular uptake. However, prior studies have shown that intravenous injection of PEG-SOD does not protect animals against O2 toxicity. In this study, we demonstrated that tracheal insufflation of PEG-SOD resulted in a dose-dependent protection against O2 toxicity. Nine of 15 rats (60%) insufflated with 25,000 U PEG-SOD survived continuous 100% O2 exposure for more than 7 days compared with control rats (n = 45), all of which died within 3 days of O2 exposure (P < 0.025). In contrast, insufflation of 25,000 U SOD, 9.7 mg methoxy-PEG (equivalent to the amount of methoxy-PEG present in 25,000 U PEG-SOD), or a combination of SOD and methoxy-PEG had no protective effect. Furthermore, intravenous or intraperitoneal injection of PEG-SOD did not afford significant protection. Protection against O2 toxicity by PEG-SOD insufflation was associated with attenuated O2-induced pulmonary injury as evidenced by a reduced volume of pleural effusion. Insufflation of PEG-SOD markedly increased pulmonary SOD activity (to 300 and 370% of controls at 24 and 50 h, respectively) without affecting pulmonary catalase activity. We conclude that insufflation of PEG-SOD protects rats against O2 toxicity, possibly by enhancing pulmonary SOD activity.

The adjuvant activity of pyrene in diesel exhaust on IgE antibody production in mice.

Abstract: In this communication, it is shown that pyrene has an adjuvant activity on IgE antibody production when mice are immunized by an intraperitoneal injection of ovalbumin (OA) or Japanese cedar pollen allergen (JCPA) with pyrene. The effects of pyrene on IgE antibody production in mice were investigated to clarify the relation between pollen allergy and the adjuvanticity of the chemical compounds contained in diesel-exhaust particulates (DEP). In the first experiment, three groups of mice were immunized intraperitoneally six times at 2-week intervals with 1 microgram of OA alone, 1 microgram of OA plus 1 mg of pyrene, and 1 microgram of OA plus 1 mg of DEP, respectively. The IgE antibody responses to OA in mice immunized with OA plus pyrene or OA plus DEP were extremely enhanced as compared with those in mice immunized with OA alone, and the highest responses were observed in mice immunized with OA plus DEP. In the second experiment, mice were immunized with 10 micrograms of JCPA alone or 10 micrograms of JCPA plus 5 mg of pyrene in the same way. The IgE antibody responses to JCPA in mice immunized with JCPA plus pyrene were higher than those in mice immunized with JCPA alone. The intraperitoneal macrophages of the mice also clearly stimulated in vitro by pyrene on chemiluminescence assay. These results suggest that pyrene contained in DEP acts as an adjuvant in IgE antibody production when mice are immunized with antigens.

Effects of alpha- and beta-adrenergic antagonists on rise in body temperature induced by psychological stress in rats.

Abstract: We investigated the effects of intraperitoneal injection of alpha- and beta-adrenergic antagonists on psychological stress-induced responses in free-moving rats. Psychological stress was induced by immersion in 2-cm-deep water. The intraperitoneal injection of the alpha-adrenergic blocker, phentolamine (10 mg/kg), attenuated the stress-induced rise in body temperature and hypertension but enhanced tachycardia. In contrast, intraperitoneal injection of the beta-adrenergic blocker, propranolol (1 mg/kg), suppressed tachycardia but had no effect on rise in body temperature and hypertension during stress. The intraperitoneal injection of both blockers had no effect on the increase in metabolic rate (O2 consumption) induced by stress. The intravenous injection of propranolol (1 mg/kg) suppressed the stress-induced rise in body temperature. We then examined the effect of intracerebroventricular injection of propranolol on the stress-induced rise in body temperature and found that intracerebroventricular injection of propranolol (50 micrograms) suppressed the stress-induced rise in body temperature. These results support the following hypotheses: 1) Systemic injection of phentolamine suppresses the psychological stress-induced rise in body temperature by facilitating heat-loss; 2) Peripheral beta-adrenergic stimulation probably does not contribute to psychological stress-induced rises in body temperature; and 3) central beta-adrenergic receptors are important in stress-induced increases in body temperature.

Role of local pancreatic blood flow in development of hemorrhagic pancreatitis induced by stress in rats.

Abstract: Our previous data showed that the pancreatitis induced in rats by cerulein develops into hemorrhagic pancreatitis following water-immersion stress. The present study examined the effects of water-immersion stress and high doses of cerulein (intraperitoneal injection) on pancreatic blood flow. Five hours of water-immersion stress reduced the local pancreatic blood flow to approximately 30% of the initial value (253.75 +/- 12.58 ml/min/100 g) without causing any histological alterations. Blood flow was decreased as early as 1 h after the immersion and reached the lowest value (30% of initial value) 3 h after the immersion. The administration of 40 micrograms/kg body wt cerulein as two intraperitoneal injections reduced the pancreatic blood flow by 40% 5 h after the first cerulein injection. The injections of cerulein combined with water-immersion stress did not reduce the pancreatic blood flow more than did water-immersion stress alone. The systemic blood pressure was unaffected during 5 h of water immersion after the cerulein injections. These findings suggest that in rats the stress-induced decrease of local pancreatic blood flow may not produce pancreatitis, but may aggravate an existing acute pancreatitis.

Interleukin-2 enhances scopolamine-induced amnesia and hyperactivity in the mouse

Abstract: We studied the effects of human recombinant interleukin-2 (IL-2) on scopolamine-induced amnesia for a passive avoidance response and on scopolamine-induced hyperactivity, in the mouse. The pre-training intraperitoneal administration of the cytokine significantly enhanced the amnesic effect of scopolamine (1.0 mg kg-1 i.p.). Similar effects were observed after repeated administration (2,500 IU/mouse i.p. for 10 days) of the cytokine. In this condition, the treatment with the pro-cholinergic drug acetylcarnitine completely blocked the pro-amnesic effect of IL-2. The cytokine did not affect plasma glucose concentrations, nor induced any change in footshock sensitivity. Intraperitoneal injection of IL-2 significantly enhanced the scopolamine-induced hyperactivity, whereas the cytokine alone was ineffective in modifying locomotor activity. Our results suggest an involvement of the cholinergic system in the neuromodulatory action of IL-2.

Effect of tumor necrosis factor or interleukin-1 on muscle amino acid uptake and the role of glucocorticoids.

Abstract: Muscle amino acid uptake is inhibited during sepsis and endotoxemia. Cytokines, in particular tumor necrosis factor (TNF) and interleukin-1 (IL-1), have been implicated as mediators of metabolic alterations in sepsis and other critical illness. In this study, we examined the effect of TNF and IL-1 on muscle amino acid uptake and tested the hypothesis that cytokine-induced changes in muscle amino acid uptake are mediated by glucocorticoids. Intraperitoneal injection in rats of 100 micrograms per kilogram body weight of human recombinant TNF alpha (rTNF alpha) or rIL-1 alpha resulted, two hours later, in 36 and 24 percent reduction, respectively, of amino acid transport in incubated soleus muscles, determined as intracellular uptake of alpha-aminoisobutyric acid. When rats were treated with the glucocorticoid receptor antagonist RU 38486 (5 milligrams per kilogram of body weight) two hours before cytokine injection, the inhibitory effect on muscle amino acid transport of TNF was blocked, whereas that of IL-1 was unaffected. The present results suggest that TNF and IL-1 may regulate amino acid transport in skeletal muscle and that the effect of TNF, but not that of IL-1, is at least partly mediated by glucocorticoids.

Prostate tumor cell invasion: a comparison of orthotopic and ectopic models.

Abstract: Interest in orthotopic models has been generated by recent reports of increased invasive and metastatic potential demonstrated by tumor cell lines following injection into their tissue of origin rather than subcutaneously We have previously demonstrated that transfection of the tumorigenic human prostate cell line, Du-145, with the metalloproteinase matrilysin increased its ability to invade the diaphragm following an intraperitoneal injection In this study we compare the invasive and metastatic behavior of transfected Du-145 cell lines injected into the dorsal lateral lobe of the prostate to that observed when they are injected intraperitoneally Immunohistochemistry was used to examine 37 orthotopically injected severe combined immunodeficient mice for local invasion and metastatic lesions In addition, the effect of injection site on the level of expression of four genes thought to influence the invasiveness of tumor cells (matrilysin, stromelysin, TIMP-1, and TIMP-2), was determined by northern analysis of orthotopic and subcutaneous tumor tissue The results demonstrate that the level of mRNA expression of the genes examined was similar at the two sites of injection and that the invasive properties of Du-145 cells following orthotopic implantation were comparable to that observed on the diaphragm following intraperitoneal injection The advantages of the diaphragm invasion model are: less procedure-related mortality, ease of cell delivery, and provision of an easily orientated structure in which the earliest penetration of a basal lamina can be observed

Effect of beta-endorphin on sympathetic nerve activity to interscapular brown adipose tissue.

Abstract: beta-Endorphin was injected into the third cerebroventricle to investigate its effects on sympathetic nerve activity to interscapular brown adipose tissue (IBAT) in rats. Multiunit discharges of sympathetic nerves to IBAT were recorded electrophysiologically in anesthetized rats. The intracerebroventricular injection of beta-endorphin (125, 250, and 500 pmol/rat in 10 microliters) suppressed sympathetic nerve activity in a dose-related fashion (-23.9 +/- 20.4, -38.7 +/- 7.1, and -66.7 +/- 7.6% 30 min after injection) compared with preinjection baseline. N-acetyl-beta-endorphin (250 pmol) had no effect on sympathetic nerve activity to IBAT. The intraperitoneal injection of naloxone (5.0 mg/rat) did not affect sympathetic nerve activity, but preinjection of naloxone inhibited the suppressive effect of intracerebroventricular injection of beta-endorphin (250 pmol). We conclude that the intracerebroventricular administration of beta-endorphin suppressed the sympathetic nerve activity to IBAT through opioid receptors. The results of this experiment are consistent with the hypothesis that beta-endorphin has a reciprocal effect on food intake and the sympathetic nervous system.