Hyperthermic effect of a trypsin inhibitor in rats and rabbits

The influence of intraventricular and intravenous administration of trypsin inhibitor (from soya-bean) on the body temperature was studied in experiments on unanesthetized rats and rabbits. It was established that the substance provoked a steady and prolonged hyperthermia in rats and rabbits, attenuated by pre-administration of sodium salicylate. Hyperthermia was accompanied by a significant decrease in the content of PGE2 in the hypothalamus. The results suggest than inhibition of certain trypsin-like serine proteases in thermoregulatory centres may be one of the factors responsible for the development of fever.     

Impaired febrile responses to immune challenge in mice deficient in microsomal prostaglandin E synthase-1

Fever is a common, centrally elicited sign of inflammatory and infectious processes and is known to be induced by the action of PGE2 on its specific receptors in the thermogenic region of the hypothalamus. In the present work, using genetically modified mice, we examined the role of the inducible terminal PGE2-synthesizing enzyme microsomal prostaglandin E synthase-1 (mPGES-1) for the generation of immune-elicited fever. Animals with a deletion of the Ptges gene, which encodes mPGES-1, or their wild-type littermates were given either a subcutaneous injection of turpentine--a model for aseptic cytokine-induced pyresis--or an intraperitoneal injection of interleukin-1beta. While both procedures resulted in typical febrile responses in wild-type animals, these responses were strongly impaired in the mPGES-1 mutant mice. In contrast, both genotypes showed psychogenic stress-induced hyperthermia and displayed normal diurnal temperature variations. Both wild-type and mPGES-1 mutant mice also showed strongly reduced motor activity following turpentine injection. Taken together with previous observations on mPGES-1 induction in the brain vasculature during various inflammatory conditions and its role in endotoxin-induced pyresis, the present findings indicate that central PGE2 synthesis by mPGES-1 is a general and critical mechanism for fever during infectious and inflammatory conditions that is distinct from the mechanism(s) underlying the circadian temperature regulation and stress-induced hyperthermia, as well as the inflammation-induced activity depression.     

Involvement of prostaglandins in the immunosuppression occurring during experimental infection by Paracoccidioides brasiliensis

We investigated whether PGE2 mediates the immunosuppression observed during Paracoccidioides brasilensis infection. Con-A-stimulated splenocytes, isolated from mice on days 15 and 60 of infection, release high amounts of PGE2, this release was inhibited by the treatment of animals with indomethacin, sodium salicylate or meloxicam. The treatment of the animals with salicylate or meloxicam, but not indomethacin, enhanced the release of IL-2 by splenocytes from animals on day 15, but not on day 60 of infection. Furthermore, we demonstrated that the productions of TNF-alpha, IFN-gamma, IL-4, and IL-10 by Con-A-stimulated splenocytes from mice at 15 days of infection were inhibited by treatment with salicylate or meloxicam. Indomethacin inhibited only TNF-alpha and IFN-gamma production. The three treatments caused reduction of granuloma areas in the liver and lungs of infected mice. In conclusion, results suggest that the PGE2 released by COX-2 mediates the immunosuppression early on (day 15), but not during the later phase (60 days) of P. brasiliensis infection by a mechanism dependent upon IL-4 and IL-10.     

Opiate-prostaglandin interactions in the regulation of insulin secretion from rat islets of Langerhans in vitro

The inadequate insulin secretory response to glucose stimulation in non-insulin dependent diabetes has been attributed to many factors including high PGE2 levels blunting the secretory response, and to the existence of inhibitory opiate activity in vivo. The purpose of the present work was to see if there was a connection between these two independent theories. Radioimmunoassayable PGE2 in islets of Langerhans was found to be proportional to islet number and protein content and was typically 4 to 5pg/micrograms islet protein. Indomethacin (2.8 X 10(-5) M), sodium salicylate (1.25 X 10(-3) M) and chlorpropamide (7.2 X 10(-5) M) all lowered islet PGE2 levels and stimulated insulin release in vitro. Dynorphin (1-13), stimulated insulin release at a concentration of 6 X 10(-9) M, while lowering islet PGE2. Conversely, at a higher concentration, (6 X 10(-7) M), dynorphin had no stimulatory effect on insulin secretion and did not lower PGE2 levels in islets or in the incubation media. The stimulatory effects of dynorphin and sodium salicylate on insulin secretion were blocked by exogenous PGE2 (10(-5) M). PGE2 at a lower concentration (10(-9) M) did not exert any inhibitory effect on dynorphin- or sodium salicylate-induced insulin release. This concentration of exogenous PGE2 stimulated insulin release in the presence of 6mM glucose. Results from these experiments suggest that since an opioid peptide can lower endogenous PGE2 production in islets and since the stimulatory effects of the opioid peptide are reversed by exogenous PGE2 there may be interactions between these two modulators of insulin secretion.     

Neuroglobin基因体内转染对水杨酸钠给药后小鼠下丘核神经元听反应的影响

实验以48只成年健康昆明小鼠为实验对象,研究GeneJamer转染试剂介导的neuroglobin(NGB)基因体内转染对水杨酸钠给药后小鼠下丘核区听反应的影响。实验分4组,每组12只。A1组:对照组1(阴性对照,将GeneJamer转染试剂6μl和pEGFP-C12μg混合后注入下丘核脑区);A2组:对照组2[阳性对照,将GeneJamer转染试剂(6μl)和pEGFP-NGB(质粒载体pEGFP-C1与NGB基因全编码序列构建的重组子2μg)混合后注入下丘核脑区];B组:水杨酸钠给药组(450mg/kg·d-1)+pEGFP-C1;C组:水杨酸钠(450mg/kg.d-1)+pEGFP-NGB组。以直接注射法将GeneJamer转染试剂和重组质粒pEGFP-NGB混合后注入小鼠下丘核区。采用RT-PCR和Westernblot技术检测小鼠下丘核区NGBmRNA和蛋白的表达;采用细胞外记录技术,研究小鼠下丘核区神经元在水杨酸钠给药后转染重组质粒pEGFP-NGB对强度-发放率函数(刺激声强与实验鼠下丘核区神经元在接受声刺激所产生的电发放的关系曲线)、强度-潜伏期函数(刺激声强与实验鼠下丘核区神经元在接受声刺激至产生电发放潜伏期之间的关系曲线)和频率调谐曲线(实验鼠下丘核区神经元在各个频率纯音刺激下起反应的阈值绘制的曲线)的影响。实验观察到:(1)经GeneJamer转染试剂介导NGB基因可有效地转染小鼠下丘核区脑组织并得到表达。(2)水杨酸钠给药后神经元的强度-发放率函数曲线升高。对照组A1、A2各项指标进行比较均无统计学意义。对照组A1、A2和水杨酸钠+pEGFP-NGB组神经元的强度-发放率函数以非单调型(随刺激强度增加时,发放率表现为先降后升呈“V”形或“U”形)为主,分别占74.6%、72.2%和59.3%,水杨酸钠给药组以不规则型强度-发放率函数为主,占47%,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.01、P<0.05)。(3)水杨酸钠给药后神经元的强度-潜伏期函数曲线降低。对照组A1、A2各项指标进行比较均无统计学意义。水杨酸钠给药组以非单调型强度-潜伏期率函数为主,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.05)。(4)A1和A2对照组听反应神经元的调谐曲线,Q-10dB值均大于5.00,其调谐曲线为狭窄型。记录水杨酸钠给药组72个听神经元的调谐曲线,有53个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.12,其调谐曲线为宽阔型;其余19个神经元的Q-10dB值大于5.00,属于狭窄型调谐曲线。水杨酸钠+pEGFP-NGB组67个听神经元的调谐曲线,有12个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.87,其调谐曲线为宽阔型,其它的神经元的值大于5.00。它们的调谐曲线均属狭窄型。以上结果提示外源性NGB基因在水杨酸钠给药后小鼠下丘核区局部高表达,提示GeneJamer转染试剂介导NGB体内转基因治疗水杨酸钠引起的下丘核区的损伤的方法是可行的。实验小鼠转染NGB基因后可逆转因水杨酸钠给药引起的强度-发放率函数曲线升高以及强度-潜伏期函数曲线降低,并可逆转水杨酸钠引起的部分听神经元对声刺激强度的编码类型。     

Hyperthermia,antipyretics and function of polymorphonuclear leukocytes.

Whether hyperthermia (temperature, 40 degrees C), salicylates, acetaminophen or phenacetin has an adverse effect on polymorphonuclear leukocyte (PMNL) function was examined. Migration experiemnts were carried out in Boyden chambers with bacterial chemotactic factor as the attract, and bactericidal assays were done with Staphylococcus aureus and serum from an AB blood group donor as a source of opsonins. PMNL viability was determined by the trypan blue exclusion method. Neither hyperthermia nor any of the drugs tested affected PMNL viability adversely, but sodium salicylate and phenacetin suppressed PMNL migration. Early staphylococcal killing was greater at 40 degrees C; however, after 2 hours the converse was true. Bactericidal activity was suppressed by acetylsalicylic acid, sodium salicylate and phenacetin. Hence it appears PMNL function is similar at 37 degrees and 40 degrees C but that some commonly used antipyretics have an adverse effect on PMNL activity.     

Inducible cyclooxygenase released prostaglandin mediates immunosuppression in acute phase of experimental Trypanosoma cruzi infection

We investigated the possible role of prostaglandins produced by COX-2 in the immunosuppression observed during Trypanosoma cruzi infection. Con-A-stimulated splenocytes isolated from mice on days 5, 10, and 15 of infection released large amounts of PGE2 and this release was inhibited by the treatment of animals with sodium salicylate or meloxicam. The treatment of the animals with these drugs enhanced the release of IL-2 by splenocytes from T. cruzi-infected animals and significantly reduced the blood parasitemia and delayed the mortality of the infected mice. Furthermore, the release of TNF-alpha, IFN-gamma, IL-4, and IL-10 by Con-A-stimulated splenocytes obtained from infected mice on days 5, 10, and 15 of the infection was significantly inhibited by treatment of the animals with salicylate or meloxicam. In conclusion, the results suggest that the prostaglandins produced mainly by COX-2 mediate the immunosuppression observed in the acute phase of T. cruzi infection.     

Blunted febrile response to intravenous endotoxin in starved rats

The effects of fasting on the febrile responses to intravenous injection of bacterial lipopolysaccharide (LPS; endotoxin) of Escherichia coli were investigated in rats. Ad libitum-fed rats (C) produced a biphasic fever with an increase in the temperature difference between brown adipose tissue and colon and shivering activity (SA). Measurement by a direct calorimeter showed no particular changes in heat loss. Rats starved for 4 days (F4) responded to intravenous LPS with a monophasic fever accompanied by an increase in SA only. However the maximal rise in colonic temperature (Tco) did not differ from C rats. Subsequent 2-day fasting reduced SA and the maximal fever height. Endogenous pyrogen (EP) injected intravenously produced a prompt rise in Tco followed by prolonged hyperthermia in C rats. In the F4 rats, there was no such sustained rise in Tco as a result of intravenous EP. The response in Tco to intravenous prostaglandin E2 (PGE2) was the same in fed and starved rats. The administration of LPS, EP, and PGE2 into the lateral ventricle evoked a similar extent of hyperthermia in C and F4 rats. Because the second phase of fever has been shown to occur after pyrogens are translated into a febrile stimulus within the blood-brain barrier, it is assumed that the functional changes of the blood-brain barrier such as in the permeability of pyrogens or in the sensitivity of pyrogen receptors resulted in the absence of the second phase of fever in starved rats.     

Sensitivity of hypothalamic sites to salicylate and prostaglandin.

This study was designed to determine the dose of salicylate necessary to produce substantial antipyresis, and to determine the relationship between the response to salicylate and prostaglandin infused into the same region of the preoptic area of the rabbit. The effect of preoptic infusions of three doses of sodium salicylate, or a control solution, on the fever produced by an intravenous injection of endogenous pyrogen was measured. The pyrogenic response to prostaglandin E1 injected into the same preoptic sites in the same rabbits was also monitored. The results showed that the 50 microgram/microL per hour dose of salicylate did not produce significant antipyresis but that the 100 and 200 microgram/microL per hour doses did. The results also showed a significant correlation between the magnitude of fever produced by prostaglandin E1 and the magnitude of antipyresis produced by sodium salicylate at a particular site. Those sites at which infusion of salicylate produced the most effective antipyresis were also the ones at which prostaglandin E1 produced the largest fevers.     

2-Deoxy-D-glucose prevents and nicotinamide potentiates 3, 4-methylenedioxymethamphetamine-induced serotonin neurotoxicity

Neurotoxicity induced by different substituted amphetamines has been associated with the exhaustion of intracellular energy stores. Accordingly, we examined the influence of 2-deoxy-D-glucose (2-DG), a competitive inhibitor of glucose uptake and metabolism, and nicotinamide, an agent that improves energy metabolism, on 3, 4-methylenedioxymethamphetamine (MDMA)-induced 5-hydroxytryptamine (5-HT; serotonin) deficits. Administration of MDMA (15 mg/kg i.p.) produced a significant hyperthermia, whereas 2-DG caused a profound hypothermia that lasted throughout the experiment. When MDMA was given to 2-DG-treated rats, an immediate but transient hyperthermia occurred and was followed by a return to hypothermia. 2-DG had no effect on 5-HT concentrations in the frontal cortex, hippocampus, and striatum but prevented the neurotoxicity induced by MDMA. When rats were injected with 2-DG/MDMA and were warmed to prevent hypothermia, the protection afforded by 2-DG was abolished. Nicotinamide had no effect on body temperature of the rats, and the hyperthermia induced by the nicotinamide/MDMA treatment was similar to that of the saline/MDMA-treated rats. However, the long-term 5-HT deficits induced by MDMA were potentiated by nicotinamide in all the brain regions examined. Finally, no change on ATP concentrations in the frontal cortex, hippocampus, and striatum was observed up to 3 h after a single dose of MDMA. These results suggest that an altered energy metabolism is not the main cause of the neurotoxic effects induced by MDMA.     

Calorimetric study of the effect of salicylate in man during heat exposure and exercise (author's transl)]

1. The effect of sodium acetylo-salicylate (2 g per os) on the thermoregulatory responses of 10 male subjects was studied by direct and indirect calorimetry during two tests : heat exposure at 37 degrees C and exercise (50 W) at 25 degrees C. Both test were performed twice : with salicylate treatment and with a placebo. 2. During heat exposure at 37 degrees C for 75 min, the rise in tympanic temperature (Tty) and in mean skin temperature Ts, the time course of heat losses by radiation (R), convection (C) and evaporation (E), and the metabolic rate (M), measured by oxygen consumption, were not altered by salicylate treatment. 3. During exercise, salicylate treatment did not affect the time course of Tty and Ts, (R + C) and M. However, salicylate treatment decreased the delay for triggering the evaporative response (E) to the thermal load; similarly, the increase in cutaneous blood flow was triggered sooner in subjected receiving salicylate than in controls. 4. In conclusion, these results suggest that, during exercise, the thermal controller triggers thermoregulatory responses during passive hyperthermia by heat exposure.     

Physiological antagonism between prostaglandin E2 and neuropeptide Y on thermoregulation in the dog

These experiments were undertaken to determine whether neuropeptide Y (NPY) could suppress a prostaglandin hyperthermia in conscious dogs. Prostaglandin E2 (PGE2) (5 micrograms), injected into the lateral cerebral ventricle (ILV), evoked a hyperthermia of approximately 1 degrees C. Addition of ILV NPY (5 micrograms) significantly attenuated the PGE2-induced hyperthermia, whereas pancreatic polypeptide (PP), another member of the PP family peptide, did not. These results provide evidence for a role of NPY on thermoregulation in the dog.     

Involvement of prostaglandins and histamine in radiation-induced temperature responses in rats

Exposure of rats to 1-15 Gy of gamma radiation induced hyperthermia, whereas exposure to 20-150 Gy produced hypothermia. Since radiation exposure induced the release of prostaglandins (PGs) and histamine, the role of PGs and histamine in radiation-induced temperature changes was examined. Radiation-induced hyper- and hypothermia were antagonized by pretreatment with indomethacin, a cyclooxygenase inhibitor. Intracerebroventricular administration of PGE2 and PGD2 induced hyper- and hypothermia, respectively. Administration of SC-19220, a specific PGE2 antagonist, attenuated PGE2- and radiation-induced hyperthermia, but it did not antagonize PGD2- or radiation-induced hypothermia. Consistent with an apparent role of histamine in hypothermia, administration of disodium cromoglycate (a mast cell stabilizer), mepyramine (H1-receptor antagonist), or cimetidine (H2-receptor antagonist) attenuated PGD2- and radiation-induced hypothermia. These results suggest that radiation-induced hyperthermia is mediated via PGE2 and that radiation-induced hypothermia is mediated by another PG, possibly PGD2, via histamine.     

Glucose transport and catabolite repression in Endomycopsis fibuligera yeasts

The role of systems for glucose transport in the manifestation of carbon catabolite repression of glucoamylase synthesis was studied in the yeast Endomycopsis fibuligera. Experimentas were conducted with its mutant AB-192 defective in the system of transport universal for glucose and 2-deoxy-D-glucose (2-DG). The nature of the mutation was established from the following data: (1) transport of labeled glucose into the mutant cells was twice as low in comparison with the parent culture 20-9; (2) transport of labeled 2-DG was suppressed almost entirely; (3) no competition was found between glucose and 2-DG for penetration into the mutant cells. Glucoamylase synthesis in the mutant AB-192 was not sensitive to catabolite repression by glucose. This was confirmed by the resistance of the AB-192 cells to the inhibition by glucose and their complete resistance to the repression by 2-DG. Moreover, an addition of cAMP did not stimulate glucoamylase synthesis by the mutant culture in the presence of glucose and 2-DG. It can be concluded therefore that the resistance of the yeast to catabolite repression by the glucose is caused by the mutation in the system for carbohydrate transport. The results suggest that the system of glucose transport plays an important role in the manifestation of carbon catabolite repression in the yeast Endomycopsis fibuligera.     

Expanding the febrigenic role of cyclooxygenase-2 to the previously overlooked responses

Previous studies on the role of cyclooxygenase (COX)-1 and -2 in fever induced by intravenous LPS have failed to investigate the role of these isoenzymes in the earliest responses: monophasic fever (response to a low, near-threshold dose of LPS) and the first phase of polyphasic fever (response to higher doses). We studied these responses in 96 mice that were COX-1 or COX-2 deficient (-/-) or sufficient (+/+). Each mouse was implanted with a temperature telemetry probe into the peritoneal cavity and a jugular catheter. The study was conducted at a tightly controlled, neutral ambient temperature (31 degrees C). To avoid stress hyperthermia (which masks the onset of fever), all injections were performed through a catheter extension. The +/+ mice responded to intravenous saline with no change in deep body temperature. To a low dose of LPS (1 microg/kg iv), they responded with a monophasic fever. To a higher dose (56 microg/kg), they responded with a polyphasic fever. Neither monophasic fever nor the first phase of polyphasic fever was attenuated in the COX-1 -/- mice, but both responses were absent in the COX-2 -/- mice. The second and third phases of polyphasic fever were also missing in the COX-2 -/- mice. The present study identifies a new, critical role for COX-2 in the mediation of the earliest responses to intravenous LPS: monophasic fever and the first phase of polyphasic fever. It also suggests that no product of the COX-1 gene, including the splice variant COX-1b (COX-3), is essential for these responses.     

Inhibition of T cell-mediated cytolysis by 2-deoxy-D-glucose (2-DG): differential effect of 2-DG on effector cells isolated early or late after alloantigenic stimulation in vitro.

The effect of the hexose analogue 2-deoxy-D-glucose (2-DG) on the functional activity of various populations of cytolytic T lymphocytes (CTL) has been compared. Under aerobic conditions, CTL harvested at the peak of the response (day 4) in primary or secondary mixed leukocyte cultures (MLC) were much more readily inhibited by 2-DG that CTL obtained from MLC at later times (day 11 to 18) or from the peritoneal cavity of alloimmune mice. Quantitatively, 0.4 mM 2-DG was sufficpient to inhibit cytolysis by 50% in day 4 CTL populatons, whereas 25 mM had little or no effect on day 11 to 18 CTL. Evidence was obtained that inhibition of cytolysis by 2-DG under these conditions was accompanied by a parallel inhibition of effector:target cell binding. In contradistinction to these findings, the cytolytic activity of both day 4 and day 11 MLC cells was readily inhibited by 2-DG under conditions where cell respiration was blocked by sodium azide. Furthermore, uptake of radiolabeled 2-DG was observed under aerobic conditions in both day 4 and day 11 MLC cells. These results strongly suggest that inhibition of cytolysis by 2-DG under aerobic conditions is mediated via a direct effect on CTL which is independent of the consequences of energy depletion. An indirect method by which CTL may be inhibited by 2-DG is suggested.     

Production and purification of salicylate monooxygenase from Pseudomonas cepacia ATCC 29351.

Salicylate monooxygenase (EC: 1.14.13.1) has been produced and purified from Pseudomonas cepacia ATCC 29351 which has the ability to utilise salicylate as a sole carbon source. The bacterium was grown on a defined medium containing 2% (w/v) casamino acids and 0.15% (w/v) yeast extract at 25 degrees C; salicylate monooxygenase production was induced by the presence of up to 0.7% (w/v) sodium salicylate, to a level of approximately 2% of the soluble cell protein. The enzyme was purified over 50-fold, with a recovery of about 40%, by a combination of ion exchange and hydrophobic interaction chromatography. The purified enzyme had a specific activity of 14-15 U mg-1 protein and was essentially homogeneous.     

Reduction of the hyperthermic effect of prostaglandin E2 by cholinomimetics, monoamines and calcium ions]

It was shown in experiments on unanesthetized rats with prostaglandin E2 (PGE2) hyperthermia, not preventable by aspirin that intraventricular (into the lateral ventricle) injections of arecoline, noradrenaline, 5-hydroxytryptamine (5-HT), histamine, and calcium ions and intraperitoneal eserine injection were capable of decreasing body temperature. PGE2 hyperthermia was not prevented by aspirin, but it was reduced by eserine. After the administration of arecoline and nicotine into the third ventricle of unanesthetized rabbits with PGE2 hyperthermia body temperature decreased as well. The effect of arecoline and 5-HT was reproducible in the same animals. The data are suggestive of the existence in the heat loss centre of mechanisms including cholinergic neurons whose activity was not completely suppressed by PGE2.