Reaction In Rabbits Research Articles

Hypothalamic, midbrain and bulbar areas involved in the defense reaction in rabbits

The present study mapped neuroanatomical sites in the hypothalamus and periaqueductal gray (PAG) of the rabbit which, when stimulated electrically, evoked the cardiorespiratory components of the defense reaction (CRDR). This included increases in heart rate, blood pressure, hindlimb blood flow and respiration rate. All of the components of the CRDR were elicited by electrical stimulation of the posterior hypothalamus, at sites dorsal and medial to the fornix. Although there were regions throughout the PAG in which electrical stimulation elicited concomitant increases in blood pressure, hindlimb blood flow and respiration rate, only stimulation of the dorsal PAG evoked tachycardia. Injection of horseradish peroxidase into the rostral ventrolateral medulla (RVLM) led to heavy retrograde and anterograde labeling in the region of the hypothalamus that yielded the CRDR when stimulated electrically. Heavy labeling was also observed in the dorsal and ventral PAG. The results of this study provide evidence that the posterior hypothalamus and the dorsal PAG are nodal structures in the mediation of the CRDR and that cells in posterior hypothalamus, dorsal PAG and ventral PAG make monosynaptic connections with the RVLM.

Comparison of different prothrombin complex concentrates - in vitro and in vivo studies

The potency and tests for thrombogenicity were studied prospectively in 7 different (two lots of each brand, A - G) prothrombin complex concentrates (PCC). Human albumine (H) and a factor IX concentrate (I), served as controls. The potency of coagulation factors and inhibitors varied considerably. Two brands (E, F) contained no protein S, additionally one brand contained no protein C. Two preparations exhibited high amidolytic activities, especially towards the thrombin-sensitive chromogenic substrate S-2238, in vitro. These activities could be quenched in part by the addition of hirudin or antithrombin III. The heparin and antithrombin III content of the PCCs was significantly different, and, after addition of antithrombin III an increase of thrombin-antithrombin III complexes in 2 preparations (B, D) was observed in vitro. Additionally, three brands (B, D, F) caused more severe cardio-pulmonary reactions in rabbits, associated with an increase of fibrin split products for brands B and D. We conclude that the use of these preparations in patients, in whom an acquired protein C or S defect, or a hypercoagulable state, can be suspected, cannot be recommended.

Isolation and characterization of lipopolysaccharide from Centipeda periodontii ATCC 35019

Lipopolysaccharide (LPS) was extracted from cells of Centipeda periodontii ATCC 35019 by a hot phenol-water method, purified by nuclease treatment and by repeated ultracentrifugations. The LPS was composed of 21.7% hexose, 9.1% hexosamine, 10.3% fatty acid, 0.5% protein, 2.5% phosphorus, 4.3% 2-keto-3-deoxyoctonate(KDO) and 2.3% heptose. The major fatty acids of the LPS were 3OH C13:0 and C13:0. C. periodontii LPS was able to gelatinize Limulus amebocyte and to produce the local Schwartzman reaction in rabbits. LPS from C. periodontii exhibited strong immunobiological activities, mitogenicity on splenocytes of C3H/HeN mice, and stimulation of interleukin 1 (IL-1) production in peritoneal macrophages of C3H/HeN mice.

Association between protective efficacy of anti-lipopolysaccharide (LPS) antibodies and suppression of LPS-induced tumor necrosis factor alpha and interleukin 6. Comparison of O side chain-specific antibodies with core LPS antibodies.

Two-core LPS antibodies, the rabbit J5 polyclonal antiserum and the human anti-lipid A IgM mAb HA-1A, did not improve the survival of mice challenged with E. coli O111 or P. aeruginosa 3, or with the LPS extracted from them, and did not decrease the incidence of Shwartzman reactions in rabbits challenged with O111 LPS. In contrast, O side chain-specific rabbit antisera were protective in these models. The protection afforded by O side chain-specific antisera against endotoxin lethality was associated with decreased LPS-induced serum TNF and IL-6 levels, whereas core LPS antibodies had no effect on TNF or IL-6 levels. The absence of reduction of LPS-induced cytokines levels by core LPS antibodies suggests that these antibodies are not able to prevent the interactions between LPS and target cells.

Chemical, immunobiological and antigenic characterizations of lipopolysaccharides from Bacteroides gingivalis strains

Lipopolysaccharides (LPS) were extracted from whole cells of seven strains of Bacteroides gingivalis--381, ATCC 33277, BH18/10, OMZ314, OMZ406, 6/26 and HW24D-1--by the phenol/water procedure, and purified by treatment with nuclease and by repeated ultracentrifugation. These LPS were composed of hexoses, hexosamines, fatty acids, phosphorus and phosphorylated 2-keto-3-deoxyoctonate (KDO). The major components of the lipid portion of these LPS were hexadecanoic, 3-hydroxyhexadecanoic, branched 3-hydroxypentadecanoic and branched 3-hydroxyheptadecanoic acids. All the LPS preparations induced marked mitogenic and in vitro polyclonal B cell activation responses in spleen cells from both C3H/HeN and C3H/HeJ mice, exhibited no definitive preparatory activity in the local Shwartzman reaction in rabbits, but were active in the chromogenic Limulus amoebocyte lysate test. A monoclonal antibody (mAb) raised against the LPS from B. gingivalis strain 6/26 reacted with LPS from all other B. gingivalis strains tested. Other mAbs raised against LPS from B. gingivalis strains 381 and 6/26 reacted with the LPS from strains 381, ATCC 33277, BH18/10 and 6/26 (these strains were termed LPS serogroup I), as revealed by ELISA and immunodiffusion. The LPS from these strains except for 6/26 showed almost identical patterns in SDS-PAGE stained with ammoniacal silver. A mAb raised against the LPS from B. gingivalis HW24D-1 reacted with the LPS from strains OMZ314, HW24D-1 and OMZ409 (LPS serogroup II). These LPS, except OMZ409, exhibited very similar profiles in SDS-PAGE. These results indicate that there are at least two different antigenic groups present among LPS from B. gingivalis strains, as well as a common, species-specific antigen.

Time-course of opioid and pituitary-adrenal hormone modifications during the immobility reaction in rabbits

A series of experiments in male rabbits examined the influence of tonic immobility (animal hypnosis) on the opioid and pituitary-adrenal hormones. The aims of the experiments were to follow the temporal modifications in hormone parameters and to discriminate the effects of immobility from those of the manipulative procedure to induce the reaction. Results show that immobility elicits increases in plasma ACTH and β-EP, but no modifications in pituitary β-EP. The effects of induction procedure were dissociable from those of immobility, the most marked effect being a prolonged, sustained increase of corticosterone plasma levels. Results support the hypothesis of the opioid involvement in the physiological control of immobility reaction and indicate different mechanisms underlying the immobility response and the procedure of induction.

Preparation of antibodies to king cobra (Ophiophagus hannah) venom hemorrhagin and investigation of their cross-reactivity

N.-H. Tan, M. N. Saifuddin and M. I. Nik Jaafar. Preparation of antibodies to king cobra ( Ophiophagus hannah) venom hemorrhagin and investigation of their cross-reactivity. Toxicon 28, 1355–1359, 1990.—Hannahtoxin, the major hemorrhagin purified from king cobra ( Ophiophagus hannah) venom, elicits hemorrhages in rabbits but not in mice. Two antisera against hannahtoxin were prepared: one raised against purified hannahtoxin, while the other was raised against glutaraldehyde cross-linked and detoxified hannahtoxin. The antisera were refined by pepsin digestion and ammonium sulfate precipitation. They are of approximately equal potency in their ability to neutralize the hemorrhagic activity of king cobra venom in rabbits. The antisera did not form a precipitin line with venom of snakes of the Viperidae family nor neutralize hemorrhages elicited in mice by any of these venoms. However, when the hemorrhagic activity was assayed in rabbits, both antisera were able to abolish the hemorrhages elicited by all of the venoms tested. These results suggest that hannahtoxin displays few epitopes in common with hemorrhagins of viperid venoms, except those involved in the neutralization of hemorrhagic activity in rabbits. The epitopes of viperid venom hemorrhagins involved in the neutralization reaction in rabbits are different from those in mice.

Immobility reactions in socially behaving rabbits: Relation to hippocampal electrical activity

The presence of an intruder conspecific of the same sex caused a series of conflict reactions in rabbits living in a semi-natural environment. In some animals, defensive responses were predominant and two immobility reactions were observed. One consisted of freezing when the intruder was exploring at a distance; the other consisted of subdued posture in close contact with the intruder. Hippocampal EEG, recorded by telemetry, showed two different profiles. During freezing, rhythmic slow activity prevailed and during subdued posture an irregular pattern was predominant. Frequency increased when the intruder was in close contact with the resident. Aspects such as distance or behaviour of the intruder were found to affect both behavioural strategies and hippocampal electrical responses.

Endotoxic properties of chemically synthesized lipid A analogs. Studies on six inflammatory reactions in vivo, and one reaction in vitro.

Biological activities of two groups of synthesized lipid A analogs, the counterpart of biosynthetic precursor, Lehmann's Ia type, 406, and E. coli lipid A type, 506, as well as their non-phosphorylated, and mono-phosphorylated analogs were investigated. The activities employed included four bone marrow cell reactions in mice, mice skin reaction, leukocytes migration in rabbits' cornea, and hemagglutination. Compound 406 and 506 elicited bone marrow reactions in mice and hemagglutination of mouse RBC, although 406 failed to elicit hemorrhage and necrosis also in mice skin. Compound 406 did not elicit corneal reaction in rabbits. The results suggest that for elicitation of this reaction and mice skin reaction, acyloxyacyl structure is required. Cytotoxicity and thromboplastin production of four bone marrow reactions had been reported by us to be endotoxic reactions, since these had not been elicited by peptidoglycan of Lactobacillus and Staphylococcus (1981) and 300 series synthesized analogs (1984) which did not have endotoxic structures. From these results, it seems that these two marrow reactions and hemagglutination require, as does the limulus test, the lipid A part structure as is present in 406.

Changes in Trypsin-Binding Properties and Conformation of Rabbit α-2-Macroglobulin on Reaction with Methylamine

Reactions of rabbit alpha-2-macroglobulin with methylamine and trypsin were studied and the results were compared with those obtained for previously described 2-macroglobulins from other species. Rabbit alpha-2-macroglobulin was cleaved by trypsin at a number of sites, whereas the human homologue was split essentially only in the "bait" region into two fragments of similar sizes. Reaction of native or methylamine-treated rabbit alpha-2-macroglobulin with trypsin resulted in a substantial decrease in the intensity of fluorescence induced by binding of 6-(p-toluidino)-2-naphthalenesulfonate or bis(8-anilino-1-naphthalenesulfonate). Under the same conditions, the fluorescence of the human protein increased. The time course of the reaction of rabbit alpha-2-macroglobulin with methylamine was studied by measuring (i) the generation of thiol groups, (ii) the decrease in trypsin-inhibiting activity with remazol brilliant blue hide powder as the substrate, and (iii) the decrease in trypsin-protein amidase activity. The thiol appearance reaction exhibited a multiphasic time course. The initial phase was found to follow second-order kinetics with an apparent rate constant of 1.2 M-1.s-1. Under the same conditions, the human protein showed monophasic kinetics with a rate constant of 12 M-1.s-1. Both the trypsin-inhibiting activity and the trypsin-protein amidase activity concurrently decreased at a slower rate than the thiol appearance. These results indicate that rabbit alpha-2-macroglobulin is more stable to nucleophilic attack by methylamine but less resistant to proteolysis by trypsin than the human homologue, and that the final conformation induced by methylamine differs considerably from that induced by trypsin.

ゴキブリアレルギーに関する研究 : 2. チャバネゴキブリ抗原の性状とヒトおよび実験動物に対するアレルゲン性

Allergenicity of the cockroach, Blattella germanica L. (B. g.), was studied by means of the following examinations, namely basophil degranulation (BD) test in rabbits and humans, passive cutaneous anaphylaxis (PCA) reaction in rabbits and rats, and prick test in humans. Also examined was the cross-antigenicity among the crude antigens of cockroaches and house-dust mites. Inhibition effect of several anti-asthmatic drugs on BD test in rabbits and humans was tested additionally. Inoculation of crude B. g. antigen into mice and rabbits produced specific IgE antibodies detectable by BD test and PCA reaction. Although the cross-antigenicities were seen among several kinds of cockroach antigens including the whole body antigens from B. g., Periplaneta americana, and P. fuliginosa, and from the feces and saliva of B. g., none of these cockroach antigens cross-reacted with the antigen from the housedust mite, Dermatophagoides farinae. Of the six fractions collected from the crude B. g. antigen through Sephadex G-100 column, F-2,with molecular weight of 25,000-45,000,showed the maximum activity in BD test in rabbits in IgE production in mice, and in the prick tests in humans who suffered from asthma. The effect of ca. 50% inhibition on BD in rabbits and humans was seen in aminophylline and ketotifen treatment each at (10)^<-3>M concentration. From these results, the BD test in rabbits proved to be one of the reliable bioassay methods applicable to the screening of anti-allergic agents.

Immobilization and restraint effects on pain reactions in animals

Acute physical restraint represents a potent Stressor in several animal species and is accompanied by a complex pattern of hormonal responses and functional changes in the central nervous system. Repeated immobilization leads to partial blunting of the behavioral and hormonal responses, with transient modifications of neurotransmitter systems in the brain. Pain reactions, as investigated by different kinds of nociceptive tests, are usually attenuated both during and immediately following acute immobilization and the analgesic effect of opiate compounds potentiated; these behavioral alterations may be attributed at least in part to activation of an endogenous opioid system. In some species, restraint may induce a reflex immobility (animal hypnosis or tonic immobility) which is also characterized by suppression of pain reactions in rabbits, probably subserved by different mechanisms. Analysis of available data suggests that pain testing in unanesthetized, restrained animals may involve alterations of the animal's reactivity to noxious stimuli.

Biological activities of chemically synthesized 2-keto-3-deoxyoctonic acid-(alpha 2----6)-D-glucosamine analogs of lipid A.

The mitogenicity, lethal toxicity, and Shwartzman reaction of three derivatives of chemically synthesized 2-keto-3-deoxyoctonic acid-linked 2,3-diacyloxyacylglucosamine-4-phosphate (KDO-GlcN-4-P) were determined. The compounds, A-301 (with di-3-hexadecanoyloxytetradecanoyl at the C-2 and C-3 positions), A-303 (di-3-tetradecanoyloxytetradecanoyl), and A-305 (3-dodecanoyloxytetradecanoyl and 3-tetradecanoyloxytetradecanoyl), induced a significant incorporation of [3H]thymidine into splenocytes of C57BL/6 mice. The compounds A-301 and A-303 showed lethality at a high dose of 50 micrograms per mouse in C57BL/6 mice sensitized with D-galactosamine, whereas A-305 caused toxicity even at a dose of 10 micrograms per mouse. However, the three compounds did not elicit the local Shwartzman reaction in rabbits. These findings indicate that the addition of 2-keto-3-deoxyoctonic acid enhances the mitogenic activity of 2,3-diacyloxyacylglucosamine-4-phosphate but does not affect the lethal toxicity and the induction of Shwartzman reaction.

Neutrophil function in an experimental model of hemolytic uremic syndrome.

To understand the role of neutrophil leukocytosis in hemolytic uremic syndrome, we studied the changes in neutrophil function in the modified generalized Shwartzman reaction in rabbits. This model resembles hemolytic uremic syndrome associated with endotoxemia. At the end of an endotoxin infusion, we observed leukopenia, thrombocytopenia, and a decrease in hematocrit associated with schistocytosis. Plasma B-glucuronidase levels increased and this was associated with a decrease in neutrophil content of the enzyme. The chemotactic index and neutrophil aggregation to zymosan-activated serum were impaired compared to controls. The neutrophil procoagulant content increased after endotoxin infusion. The serum creatinine concentration and proteinuria increased in the endotoxin-treated animals. The changes returned to normal by 48 h. Renal cortical malondialdehyde, a reflection of lipid peroxidation, was higher in the endotoxin-treated animals than in the controls. We have shown enzyme release by neutrophils, impairment of chemotaxis and aggregation, increased procoagulant content in neutrophils, and evidence of lipid peroxidation in renal cortical tissue in this model. These observations raise the possibility that leukocytes may have a role in the pathogenesis of the hemolytic uremic syndrome.

Evaluation of the Risk for Drug-Induced Postural Hypotension in an Experimental Model: Investigations with Carvedilol, Prazosin, Labetalol, and Guanethidine*

Summary: Postural hypotension is a common side effect observed in the treatment of hypertension with various drugs. Carvedilol, a vasodilating β-blocker, was compared with prazosin, labetalol, and guanethidine for its ability to induce orthostatic hypotension. The comparison was carried out using doses of the drugs required to lower baroreceptor reflex hypertension in anesthetized rabbits by 30 mm Hg (ED-30 mm Hg). The following doses were found in independent investigations to be equipotent in this rabbit model: ED-30 mm Hg (mg/kg i.v.): prazosin = 0.03; labetalol = 1.8; guanethidine = 0.12; carvedilol = 0.12. These doses did not markedly inhibit the orthostatic reaction in rabbits after tilting stress, so 10-fold higher doses were used and clear discrimination between the drugs was found. The orthostatic index was reduced after prazosin and labetalol by about 24%, after guanethidine by about 30%, and after carvedilol by about 13%. The 50-fold dose of carvedilol (6 mg/kg i.v.) does not lead to any greater inhibition of the orthostatic index. From these results it is concluded that a relatively lower risk of postural hypotension is to be expected after carvedilol treatment than with the other drugs presented here. Furthermore, these results do not provide any indication that carvedilol exerts its vasodilator properties via α-blockade.

Evaluation of the Risk for Drug-Induced Postural Hypotension in an Experimental Model

Postural hypotension is a common side effect observed in the treatment of hypertension with various drugs. Carvedilol, a vasodilating beta-blocker, was compared with prazosin, labetalol, and guanethidine for its ability to induce orthostatic hypotension. The comparison was carried out using doses of the drugs required to lower baroreceptor reflex hypertension in anesthetized rabbits by 30 mm Hg (ED -30 mm Hg). The following doses were found in independent investigations to be equipotent in this rabbit model: ED -30 mm Hg (mg/kg i.v.): prazosin = 0.03; labetalol = 1.8; guanethidine = 0.12; carvedilol = 0.12. These doses did not markedly inhibit the orthostatic reaction in rabbits after tilting stress, so 10-fold higher doses were used and clear discrimination between the drugs was found. The orthostatic index was reduced after prazosin and labetalol by about 24%, after guanethidine by about 30%, and after carvedilol by about 13%. The 50-fold dose of carvedilol (6 mg/kg i.v.) does not lead to any greater inhibition of the orthostatic index. From these results it is concluded that a relatively lower risk of postural hypotension is to be expected after carvedilol treatment than with the other drugs presented here. Furthermore, these results do not provide any indication that carvedilol exerts its vasodilator properties via alpha-blockade.

１‐（２‐Ｅｔｈｏｘｙｅｔｈｙｌ）‐２‐（４‐ｍｅｔｈｙｌ‐１‐ｈｏｍｏｐｉｐｅｒａｚｉｎｙｌ）ｂｅｎｚｉｍｉｄａｚｏｌｅ ｄｉｆｕｍａｒａｔｅ（ＫＢ‐２４１３）の抗アレルギー作用

The effects of KB-2413 on four types of allergic reactions classified by Coombs and Gell were investigated. KB-2413 inhibited homologous passive cutaneous anaphylaxis and passive anaphylactic bronchoconstriction in guinea pigs mediated by IgE-like antibody, and ED50 values were 0.0017 mg/kg, p.o., and 0.022 mg/kg, p.o., respectively. KB-2413 also inhibited IgG-mediated anaphylactic bronchoconstriction in guinea pigs actively sensitized with egg albumin. Both complement-dependent immune hemolysis and complement-independent hypotonic hemolysis were inhibited by KB-2413 in a concentration-dependent manner. KB-2413 had no effect on the Forssman systemic reaction. The passive Arthus reaction in guinea pigs sensitized with anti-egg albumin rabbit serum was unaffected by KB-2413. However, the early stage of the active Arthus reaction in rabbits sensitized with egg albumin was inhibited. KB-2413 had an inhibitory effect on the efferent phase of delayed-type hypersensitivity induced by picryl chloride (PC-DTH) in mice. On the other hand, the afferent phase of PC-DTH in mice was unaffected. These results suggest that KB-2413 strongly suppresses type I allergic reactions, and it slightly suppresses type II, III and IV allergic reactions.

Immunobiological activities of synthetic lipid A analogs with low endotoxicity

Synthetic lipid A analogs, beta(1-6)glucosamine disaccharide 1,4'-bisphosphates, which possesses four tetradecanoyl groups at the 2- and 2'-amino, and 3- and 3'-hydroxyl groups (LA-17-PP), and each two of the (R)-3-hydroxytetradecanoyl and tetradecanoyl groups at the 2- and 2'-amino and 3- and 3'-hydroxyl groups, respectively (LA-18-PP), were far less endotoxic than synthetic (506, LA-15-PP) and bacterial Escherichia coli type lipid A's; neither compound showed any detectable lethal toxicity in chicken embryos or preparatory activity for the local Shwartzman reaction in rabbits. Also both compounds were only weakly pyrogenic and comparably less lethally toxic in galactosamine-loaded mice than the reference synthetic and bacterial lipid A's and a synthetic counterpart to biosynthetic lipid A precursor Ia (406, LA-14-PP). Nevertheless, LA-17-PP and LA-18-PP exhibited definite in vivo immunoadjuvant activity in mice, and the ability to induce a possible tumor necrosis factor and alpha/beta interferon in Mycobacterium bovis BCG and Propionibacterium acnes-primed mice, respectively, although these activities were weaker than those of the reference lipid A's. 4'-Monophosphate analogs of the above two test compounds exhibited neither endotoxic nor beneficial activities, but they showed remarkable in vitro bioactivities comparable to those of the corresponding bisphosphate compounds; the ability to activate the human complement system and the clotting enzyme cascade of horseshoe crab amoebocyte lysate, stimulatory effects on guinea pig and murine peritoneal macrophages, and murine splenocytes.

Effect of Rumex nepalensis extracts on histamine, acetylcholine, carbachol, bradykinin, and PGs evoked skin reactions in rabbits

The antihistaminic, anticholinergic, antibradykinin, and/or antiprostaglandin activity of aqueous and the alcoholic leaf extracts of the plant Rumex nepalensis were tested on the prepared site on the back of rabbits, using a control and a test site. Aqueous extract was found to reduce the mean size of the wheal produced by histamine, acetylcholine, carbachol, and bradykinin. The alcoholic extract reduced the size of the wheal produced by histamine, acetylcholine and carbachol. The results indicate that Rumex nepalensis may have antihistaminic, anticholinergic, and/or antibradykinin activity.

Phase relationships of cortical potentials in rabbits during motor reactions.

1. The phase relationships involved in biopotential oscillations between the sensorimotor and visual regions during background activity in rabbit cerebral cortex are characterized by the presence of a significant spread (from 26 to 45°). 2. Light stimulation increases the number of synpasic biopotential oscillations at closely positioned sites in the cortex and decreases the spread in values of the phase shift between oscillations in the sensorimotor and visual regions of the cortex, i.e., makes the phase shifts more stable. 3. EEG of the sensorimotor and visual regions of the cortex recorded during motor reactions of rabbits in response to light stimulation exhibit theta-rhythm waves with a maximally constant phase shift.