Pathophysiological states modify levels in rat plasma of factors which inhibit synthesis and enhance breakdown of PG

We have shown recently that adaptive changes in the apparent amount of enzymes which synthesize and inactivate prostaglandins (PGs) occur in a reciprocal manner (see accompanying paper and refs 2-4). For example, PG synthetase activity in several rat organs is reduced but that of PG-metabolizing enzymes ('prostaglandinases') is increased after treatment with anti-inflammatory steroids. In view of recent reports that the synthesis of PG-like substances may be influenced by plasma factors, we wondered whether our findings may be explained in whole or in part by the presence in varying amounts of substances which affect PG synthesis and inactivation in opposite directions. We show here that rat plasma contains a protein factor(s) which inhibits the synthesis of PGs and enhances their enzymatic breakdown in vitro and which we provisionally call prostaglandin 'reciprocal coupling factor' (RCF). Furthermore, RCF is rapidly released in response to anti-inflammatory steroids and its levels are altered in the two model pathophysiological states so far investigated.     

Control of enzyme secretion by non-cholinergic, non-adrenergic nerves in guinea pig pancreas

Depolarization of pancreatic cells by exposure to high potassium solutions is associated with release of amylase. In the guinea pig, but not the mouse or cat, this Ca-dependent amylase secretion is resistant to atropine blockade, thus Scheele and Haymovits concluded that the enzyme secretion evoked by K depolarization does not involve release of transmitter from intrapancreatic nerves but is a consequence of Ca uptake into acinar cells mediated by the membrane depolarization. This hypothesis is inconsistent with current concepts of stimulus--secretion coupling in electrically non-excitable cells. The observation of Scheele and Haymovits could, however, also be explained by the release of a non-cholinergic, secretomotor transmitter as a consequence of the depolarization of intrapancreatic nerves. By adapting the technique of electrical field stimulation of isolated pancreatic segments to our studies of amylase secretion, we have now been able to demonstrate both cholinergic and non-cholinergic, non-adrenergic secretomotor nerves in the guinea pig pancreas. Excitation of the non-cholinergic nerves stimulates amylase secretion by a different intracellular coupling mechanism from that activated by cholinergic nerves or by peptides belonging to the cholecystokinin, gastrin or bombesin families.     

Synaptosomes possess an exocytotic pool of glutamate

There is increasing evidence that L-glutamate is a major excitatory neurotransmitter in the central nervous system. Immunocytochemical studies indicate that glutamate within nerve terminals may be concentrated in vesicles and glutamate-accumulating vesicles have recently been isolated. Exocytotic release of glutamate from synaptosomes (isolated nerve terminals) has not been convincingly demonstrated, however, and remains highly controversial. In order to study the kinetics of release of endogenous L-glutamate from guinea pig cerebral cortical synaptosomes we have devised a continuous enzymatic assay. This has enabled us to identify a pool, equivalent to 15-20% of the total synaptosomal glutamate, which is capable of rapid Ca2+-dependent exocytotic release.     

GABA affects the release of gastrin and somatostatin from rat antral mucosa

gamma-Aminobutyric acid (GABA) is regarded as the major inhibitory neurotransmitter in the central nervous system of vertebrates. GABA exerts its inhibitory actions by interacting with specific receptors on pre- and postsynaptic membranes and has been shown to inhibit somatostatin release from hypothalamic neurones in vitro. Concepts of innervation of the gastrointestinal tract have been expanded by recent studies which suggest that GABAergic neurones are not confined solely to the central nervous system but may also exist in the vertebrate peripheral autonomic nervous system. Jessen and coworkers have demonstrated the presence, synthesis and uptake of GABA by the myenteric plexus of the guinea pig taenia coli, and have documented the presence of glutamic acid decarboxylase (GAD) in isolated myenteric plexus. This enzyme is responsible for the conversion of glutamic acid to GABA in GABAergic neurones. The possibility that GABA may have a role in neurotransmission or neuromodulation in the enteric nervous system of the vertebrate gut has been suggested by several investigators. Furthermore, GABA receptors have been demonstrated on elements of the enteric nervous system. The effects of GABA on gastrointestinal endocrine cell function have not been examined. We report here the effects of GABA on gastrin and somatostatin release from isolated rat antral mucosa in short-term in vitro incubations.     

A saturable receptor for 32P-inositol-1,4,5-triphosphate in hepatocytes and neutrophils

Several receptors for neurotransmitters, hormones and growth factors cause accelerated phosphodiesteratic breakdown of polyphosphoinositides when activated. One of the soluble products of this reaction, inositol-1,4,5-trisphosphate (Ins(1,4,5)P3) is thought to act as a second messenger signalling the release of Ca2+ from intracellular stores. In support of this hypothesis, several studies have shown that Ins(1,4,5)P3 releases sequestered Ca2+ from permeable cells and microsomes. On the basis of certain structural requirements for Ca2+-releasing activity by inositol phosphates, it has been postulated that Ins(1,4,5)P3 acts by binding to a specific intracellular receptor, probably on a component of the endoplasmic reticulum. Here we report that 32P-Ins(1,4,5)P3 binds to a specific saturable site in permeabilized guinea pig hepatocytes and rabbit neutrophils, and that the properties of this binding site suggest that it is the physiological receptor for Ins(1,4,5)P3.     

Molecular cloning and complete amino-acid sequence of form-I phosphoinositide-specific phospholipase C

We report the molecular cloning and sequence of a phosphoinositide-specific phospholipase C (PI-PLC), an enzyme that is of particular interest because of its central role in cell signal transduction. The signals in question are those delivered by hormones to their cell-surface receptors that activate PI-PLC by means of a guanine nucleotide binding protein. Activation of the enzyme leads to the hydrolysis of phosphatidylinositol 4,5-bisphosphate to two second messengers, 1,2-diacylglycerol and inositol 1,4,5-trisphosphate, the second of which ultimately mobilizes internal pools of calcium. There are at least five PI-PLC isoenzymes, whose differences in structure and function are unknown. We have focused on isoenzyme I, which we have recently purified and characterized from guinea pig uterus. We have now determined the sequence of a full length complementary DNA of this isoenzyme from the rat. Although the sequence has little similarity with the only other sequenced PI-PLC isoenzyme, it has a surprising degree of similarity to thioredoxins, protein co-factors in thiol-dependent redox reactions.     

Involvement of nitric oxide in the reflex relaxation of the stomach to accommodate food or fluid.

The fundus of the guinea-pig stomach actively dilates in response to low increases in intragastric pressure. This physiological response, now called adaptive relaxation, accommodates the intake of liquid or food. It is independent of external innervation, resistant to ganglion blockade, but reflex in origin. The nerves involved are neither adrenergic nor cholinergic in nature. Non-adrenergic, non-cholinergic (NANC) nerves have now been recognized in many parts of the gastrointestinal tract and have recently been linked with release of nitric oxide (NO) on electrical stimulation. Here we show that adaptive relaxation in isolated stomach of the guinea pig is mediated by a NANC neurotransmitter substance indistinguishable from NO derived from L-arginine. This is substantiated by inhibition of adaptive relaxation by NG-monomethyl-L-arginine or N omega-nitro-L-arginine methyl ester, both inhibitors of NO synthesis, and by methylene blue, an inhibitor of soluble guanylate cyclase. There are two distinct neuronal pathways signalling NO-dependent adaptive relaxation, as evidenced by tetrodotoxin sensitivity. The first is a local reflex arc, the afferent fibres of which sense changes in intragastric pressure. The second is stimulated by an agonist for ganglionic nicotinic receptors. Thus, the functional significance of NO release from NANC nerves in the stomach is to bring about adaptive relaxation through a reflex response to increases in intragastric pressure.     

Prostaglandins and the synergism between VIP and noradrenaline in the cerebral cortex

We have previously shown that vasoactive intestinal peptide (VIP) and noradrenaline (NA) interact synergistically to increase cyclic AMP levels in mouse cerebral cortical slices. The pharmacological mechanism of this synergism is the potentiation by NA, through alpha 1 adrenergic receptors, of the stimulatory effect of VIP on cAMP formation. A similar interaction has been confirmed in guinea pig cerebral cortex and in discrete nuclei of the rat hypothalamus. Furthermore VIP and NA interact synergistically to depress the spontaneous activity of identified neurons in rat neocortex. At the cellular level, this synergistic interaction suggests that VIP- and NA-containing neuronal systems may converge, at least in part, on the same target cells to increase cAMP levels in the cerebral cortex. At the molecular level, the interaction may occur at various steps in signal transduction, between receptors, intramembrane transduction processes or intracellular effector mechanisms. Here we report that the alpha 1-adrenergic potentiation of the increases in cAMP elicited by VIP involves the formation of arachidonic acid metabolites and is mimicked by prostglandins F2 alpha and E2.     

4种动物血清总的补体活性比较

方法:豚鼠、人、鸡、小鼠4种动物的新鲜血清分别以全溶血,CH50为标准,在1,3,5,7,9,11,13,15 d测其总的补体活性.结果:总的补体的活性大小为,豚鼠>人>鸡>小鼠.总的补体活性随着时间的延长呈现下降趋势.豚鼠和人的血清在不稀释条件下,7 d内均能全溶血.人与豚鼠的CH50均在5~9 d出现1个下降的对数期.结论:在短时间内,人血清可以代替豚鼠血清.     

Leukotriene B, a potent chemokinetic and aggregating substance released from polymorphonuclear leukocytes

Arachidonic acid is metabolised either by cyclooxygenases to produce prostaglandins and thromboxanes or by lipoxygenases to produce mono-, di- and trihydroxyeicosatetraenoic acids (HETEs). Polymorphonuclear leukocytes (PMNs) release HETEs, including mono- and dihydroxy fatty acids, when exposed to stimuli such as the calcium ionophore A23187 (refs 1, 2). The mono-HETEs are assumed to be of particular importance with respect to effects on leukocyte function because they have been shown to possess both chemotactic and chemokinetic activities towards PMNs and eosinophils. However, we have now shown that the chemokinetic and aggregating activities released from rat and human PMNs exposed to ionophore A23187 (ref. 5) are not due to the release of mono-HETEs but to that of 5, 12-di-HETE (leukotriene B). This compound is active over the concentration range 10 pg ml-1 to 5 ng ml-1.     

The agonist effect of dihydropyridines on Ca channels

Dihydropyridines (DHP) have great potential for clinical use because of their inotropic and vasomotor effects. The mechanism of action is unknown although Ca currents have been implicated. Here we report measurements of single channel and whole cell cardiac Ca currents after application of two DHP agonists BAY K 8644 and CGP 28 392. Whole cell Ca currents from individual myocytes were increased and the 50% effective doses (ED50) were similar to those reported for contractility in rabbit aorta and guinea pig heart and catecholamine release from cat adrenal glands. The measured ED50 was also consistent with the apparent dissociation constant (Kd) of a high affinity binding site present in cardiac sarcolemmal vesicles. We propose that the molecular basis for these results is an increase in the probability that a single Ca channel, having opened and closed, will subsequently re-open during membrane depolarization. At high concentrations of BAY K 8644 and in the presence of 96 mM Ba, different effects are observed, primarily a marked prologation of open time.     

Evidence that substance P is a neurotransmitter in the myenteric plexus

Substance P (SP) is an undecapeptide originally isolated from the gut and since shown to occur within neurones in several parts of the peripheral and central nervous systems. Immunohistochemical studies indicate an exceedingly dense network of SP-containing nerves within the myenteric plexus of the guinea pig ileum. These nerves are intrinsic to the gut wall and can release SP to contract the longitudinal muscle layer. We have previously shown that SP directly depolarizes myenteric neurones and that this depolarization has a time course and ionic mechanism similar to the slow excitatory postsynaptic potential (e.p.s.p.) which can be produced by electrical stimulation of presynaptic nerves within the myenteric ganglia. We wondered whether SP might mediate this slow synaptic potential. We report here that the SP depolarization and the slow e.p.s.p. are reversibly depressed by chymotrypsin, an enzyme which degrades SP, although the responses to acetylcholine, serotonin and an unknown hyperpolarizing transmitter are unaffected. The results provide direct evidence that a peptide can mediate chemical transmission between neurones in the mammalian nervous system.     

Hartley豚鼠SPF级核心种群生长曲线与血液生理生化指标测定

目的 测定SPF级Hartley豚鼠核心群的生长体质量,血液生理、生化指标,并与清洁级豚鼠各指标进行比较。方法 选择种群中雌、雄个体各10只,通过称重,记录0～8周龄体质量;豚鼠采血,应用全自动血细胞计数仪与全自动血液生化分析仪检测各项生理、生化指标。结果 在SPF级豚鼠血液生理指标中,白细胞计数(WBC)、中性粒细胞计数(NEUT)、嗜酸性粒细胞计数(EOS) 3项指标,在雌性与雄性间有显著性差异(P0. 05)外,其他指标均存在极显著差异(P<0. 01)。结论 绘制了SPF级豚鼠生长曲线。SPF级豚鼠血液学指标在性别间有差异,与清洁级豚鼠相比存在显著差异。     

GABA may be a neurotransmitter in the vertebrate peripheral nervous system

gamma-Aminobutyric acid (GABA) is an inhibitory neurotransmitter in the peripheral nervous system of certain invertebrates and is thought to be a major transmitter in the vertebrate central nervous system. In this report we present evidence that GABA may also be a neurotransmitter in the vertebrate peripheral autonomic nervous system. We have used light and electron microscopic autoradiography to analyse high-affinity uptake of 3H-GABA into the myenteric plexus of the guinea pig taenia coli, both in situ and in a tissue culture preparation. In the isolated myenteric plexus, we have measured the specific activity of glutamic acid decarboxylase (GAD; EC 4.1.1.15), the enzyme responsible for conversion of glutamic acid to GABA in GABAergic neurones, and assessed the ability of this tissue to accumulate 3H-GABA newly synthesised from 3H-glutamic acid. Furthermore, we have measured the levels of endogenous GABA in strips of taenia coli containing the myenteric plexus.     

Novel anti-inflammatory peptides from the region of highest similarity between uteroglobin and lipocortin I

Significant future developments in the effective treatment of inflammatory diseases may arise from non-toxic dual inhibitors of both cyclooxygenase and lipoxygenase pathways in the arachidonate cascade. Inhibition of phospholipase A2(PLA2)(EC3.1.1.4), may provide such a dual action and recent research has concentrated on the role of PLA2-inhibitory proteins as possible anti-inflammatory agents. Blastokinin or uteroglobin is a steroid-induced rabbit secretory protein with PLA2-inhibitory activity. Its biochemical and biological properties have been extensively studied and its crystallographic structure has been resolved at 1.34 A (refs 15, 16). Lipocortins are a family of related proteins, which, it has been suggested, mediate the anti-inflammatory effects of glucocorticoids (for a review, see ref. 23). Some proteins of this group have been purified and the complementary DNA sequences of two human lipocortins are known. Lipocortins inhibit PLA2 in vitro, although their mechanism of action is still unclear. Recombinant lipocortin I inhibits eicosanoid synthesis in isolated perfused lungs from the guinea pig. Here, we report that synthetic oligopeptides corresponding to a region of high amino-acid sequence similarity between uteroglobin and lipocortin I have potent PLA2 inhibitory activity in vitro and striking anti-inflammatory effects in vivo.     

C—FOS蛋白在条件免疫反应哮喘动物模型的表达

目的 探讨条件免疫反应哮喘的可能发病相制。方法 利用免疫组织化学技术，研究条件反射刺激诱发支气管哮喘发作后１ｈ时豚鼠的海马结构，Ｃ－ＦＯＳ蛋白的表达情况。结果 条件反射组的诱发组和阳性对照组的动物均有Ｃ－ＦＯＳ表达，而非条件刺激组均无表达。结论 提示在脑内某些机制与条件反射建立有联系。     

韭菜(Allium tuberosum Rottler.ex Spreng.)凝集素的细胞凝集和糖抑制作用

从韭菜叶片组织分离的韭菜凝集素具有凝集细胞的作用。在测试的红细胞中能凝集小鼠、豚鼠、兔的红细胞,其中对兔的红细胞凝集活性最高。韭菜凝集素还能凝集小鼠S_(180)肉瘤细胞、大鼠W_(258)肿瘤细胞,人的Hela肿瘤细胞和MGC_(80-3)胃癌细胞、小鼠和大鼠的骨髓细胞以及牛精子细胞,而不凝集小鼠艾氏肿瘤细胞、小鼠和大鼠的脾脏淋巴细胞。韭菜凝集素的血凝活性可被D—甘露糖、D—半乳糖和D—松二糖所抑制。     

Mast cells as a source of both preformed and immunologically inducible TNF-alpha/cachectin

Tumour necrosis factor-alpha (TNF-alpha)/cachectin is a multifunctional cytokine that has effects in inflammation, sepsis, lipid and protein metabolism, haematopoiesis, angiogenesis and host resistance to parasites and malignancy. TNF-alpha was first described in activated macrophages, but certain mouse or rat mast cell populations (reviewed in refs 4,5) and some in vitro-derived human cells with cytochemical features of mast cells-basophils may also contain products similar to TNF-alpha. Here we present evidence that resident mouse peritoneal mast cells constitutively contain large amounts of TNF-alpha bioactivity, whereas cultured, immature mast cells vary in their TNF-alpha content. IgE-dependent activation of cultured or peritoneal mast cells induces extracellular release of TNF-alpha and augments levels of TNF-alpha messenger RNA and bioactivity. These findings identify mouse mast cells as an important source of both preformed and immunologically inducible TNF-alpha, and suggest that release of TNF-alpha by mast cells may contribute to host defence, the pathophysiology of allergic diseases and other processes dependent on TNF-alpha.     

Protein kinase C regulation of the receptor-coupled calcium signal in histamine-secreting rat basophilic leukaemia cells

It has been proposed that protein kinase C mediates cellular responses evoked by external stimuli, leading to alterations in internal free calcium concentrations. We have shown previously that histamine-secreting rat basophilic leukaemia cells (RBL-2H3), which degranulate on aggregation of the receptors for immunoglobulin IgE, contain a Ca2+- and phospholipid-dependent protein kinase (kinase C). The partially purified enzyme is activated directly by the tumour-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In intact RBL cells, TPA potentiates histamine release induced by the Ca2+-ionophore A23187 (similar to the synergy reported for platelets, neutrophils and rat peritoneal mast cells). Although TPA at concentrations below 15 nM synergizes with the antigen, higher TPA concentrations inhibit secretion. This selective inhibition suggested that kinase C is involved in both the activation and termination of the secretory process. To examine this possibility, we have determined the effect of TPA on changes in free cytosolic Ca2+ concentration during antigen-induced release. We report here that TPA completely blocks the increase in Ca2+ concentration induced by antigen. Our results strongly suggest that protein kinase C is involved in the regulation of receptor-dependent Ca2+ signalling.