Dynamics of the inflammatory process caused by carrageenin administration during experimental therapy

Carrageenan is shown to cause acute inflammation in mucous membrane of hamster cheek pouch and rat hind foot. Rutin has no effect on the pathological process in the cheek pouch, and arrests the first phase of inflammation in the foot. Esculamine has a therapeutic effect on both phases of inflammatory reaction in the cheek pouch and foot.     

Indices of acute inflammation against a background of lithium oxybutyrate action

The experiments on rats have shown that intraperitoneal administration of silver nitrate solution induces peritonitis while subplantar histamine, serotonin and prostaglandin E2 administration leads to an acute paw edema. Preliminary subcutaneous injection of lithium hydroxybutyrate prevents the development of inflammation.     

Effect of ethanol and zinc on ALA-dehydratase activity in red blood cells.

Subcutaneous injection of zinc as sulphate to rats activates sigma-aminolaevulinic acid dehydratase (ALA-D) in red blood cells within few days of injection. This activation counteracts the inhibitory effect of orally administered ethanol.     

Effect of lithium preparations on cardiac arrhythmias due to strophanthin in waking rats

It was shown in experiments on conscious rats that intravenous injection of strophanthine in toxic doses provokes heart arrhythmias and death of the animals. Lithium drugs (lithium chloride and lithium hydroxybutyrate) injected during arrhythmias led to a short-lived effect of heart rhythm normalization. Lithium hydroxybutyrate was more effective if administered shortly after strophanthine injection, reducing the latter's cardiotoxic effect and preventing the death of the majority of the animals.     

Effect of lithium preparations on cardiac arrhythmias resulting from ligation of the common carotid arteries

In experiments on cats with dissected vagus and aortal nerves under chloralose-urethane anesthesia, ventricular disorders of the cardiac rhythm were induced by ligation of the common carotid arteries. Appearance of arrhythmias was preceded by an increase in the sympathetic activity (recorded from the inferior cardiac or renal nerve) accompanied by a rise of the arterial blood pressure and of the heart rate. Intravenous injection of lithium chloride or hydroxybutyrate resulted in lowering of the sympathetic activity, arterial blood pressure, and heart rate, and led to the recovery of the sinus rhythm.     

Effects of desipramine on the antioxidant status in rat tissues at carrageenan‐induced paw inflammation

The pathogenesis of many diseases and different pathological conditions, including inflammation, is associated with excess production of reactive oxygen species (ROS). The present study aimed to investigate the effects of the antidepressant desipramine (DES) on carrageenan (CG)‐induced inflammation, as well as on the endogenous levels of cell enzyme and non‐enzyme antioxidants in rat liver and spleen, 4 and 24 h after CG injection. The intra‐plantar CG injection into the right hind paw resulted in a time‐dependent increase in the paw volume; the maximum of CG‐induced edema peak was in 2–4 h. A single DES dose of 20 mg·kg^?1, administered 30 min before CG, had no effect on paw edema, whereas the higher drug dose used (50 mg·kg^?1) suppressed the edematous response to CG. The latter drug dose protected CG‐induced decrease of glutathione (non‐enzyme antioxidant) in the liver; it did not affect CG‐unchanged activities of superoxide dismutase, glutathione peroxidase (enzyme antioxidants) and glucose‐6‐phosphate dehydrogenase (enzyme, important for the activity of glutathione‐conjugated antioxidant enzymes) in both liver and spleen. The drug showed an efficient antioxidant capacity in ROS‐generating chemical systems; it was higher than that of fluoxetine (another type of antidepressant). The present results suggest that the good antioxidant activity of DES might contribute to its beneficial effects in liver injuries. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of lithium preparations on the toxic effects of adrenaline

Experiments on rats have shown that intravenous injection of adrenaline in a dose of 0.3-0.4 mg/kg causes cardiac arrhythmia. In this case the primary arrhythmia developing immediately after adrenaline injection is followed by the recovery of sinusal rhythm which was replaced by the secondary arrhythmia. Apart from arrhythmias, there developed pulmonary edema. The animals died 2--3 minutes after adrenaline injections. Lithium chloride and lithium hydroxybutyrate removed the secondary arrhythmia and pulmonary edema. Lithium hydroxybutyrate has proved to be more effective.     

Redistribution of myocardial blood flow in chronic ischemia under the effects of pharmacological agents

In the experiments with anesthetized dogs under chronic myocardial ischemia the effect of propranolol, diltiazem, lithium and sodium hydroxybutyrate on the myocardial blood flow redistribution was studied with the help of ultrasonic method. The redistribution was estimated by the ratio change of blood flows in veins which drain blood directly from the focus of myocardial ischemia and total myocardial of left ventricular (v cardiac magna). It was established that propranolol increases the ratio and diltiazem decreases it. Some differences in the effect of antihypoxic drugs were revealed. Sodium hydroxybutyrate redistributed the blood flow in favour of the focus of myocardial ischemia and lithium hydroxybutyrate increased the blood flow both in the focus of myocardial ischemia and in the conditionally-intact region of myocardium of left ventricular.     

Antihypoxic effect of glucosamine in acute hypoxic states in mice]

The preventive glucosamine injection causes an increase in the survival of mice with acute hypobaric hypoxia. The injection of glucosamine, combined with sodium hydroxybutyrate greatly increased their antihypoxic activities.     

Protective action of antioxidant preparations on the development of experimental allergic encephalomyelitis in guinea pigs

The authors studied the action of combined tocopherol, lithium hydroxybutyrate and pyridoxal phosphate on the development of experimental allergic encephalomyelitis (EAE) in guinea-pigs. The use of the combined drug from the first days of immunization with encephalitis-inducing material prevented the development of EAE, activation of lipid peroxidation (LPO), and the appearance of the blood serum neurotropic activity. Administration of the combined drug starting from the 7th day after immunization appeared ineffective as was the administration of each drug alone, starting from the first days of immunization. The data obtained support an important role of LPO activation for the pathogenesis of the neuroallergic process.     

Migration of specific antibody-forming cells during the secondary immune response against horseradish peroxidase

Mice were primed subcutaneously in the hind footpads with horseradish peroxidase (HRP) and boosted intravenously 10 weeks later. Removal of the popliteal lymph nodes (draining the site of primary immunization) before the booster injection markedly depressed the secondary immune response in the spleen and bone marrow. This was taken as evidence that the secondary humoral immune response against HRP in the spleen and bone marrow is largely dependent upon immigration of cells from the popliteal lymph nodes after the booster injection. In rats primed subcutaneously in the hind footpads with HRP, antibody-forming cells were demonstrated in the blood, but not in the thoracic duct lymph 3 days after an intravenous booster injection with HRP.     

Neuroparalytic keratitis and capsaicin

Subcutaneous injection of 50 mg/kg capsaicin to newborn rats resulted in a marked decrease of heat pain sensitivity and neurogenic inflammation. There was, however, no significant difference between capsaicin-pretreated and control rats in the severity of neuroparalytic keratitis after surgical deafferentation of the eye. Retrobulbar injection of 100 microliters of 0.5% capsaicin produced keratitis-like corneal changes. These changes were not prevented by previous pretreatment with a total subcutaneous dose of 200 mg/kg capsaicin. The findings indicate that corneal changes after deafferentation are not due to excessive release of substance P and other neuropeptides from the degenerating afferent fibres.     

Flare-up of delayed-type hypersensitivity initially induced by murine cloned helper T cells

Delayed-type hypersensitivity (DTH) reactions were induced in mice by cloned helper T cells directed against methylated bovine serum albumin (mBSA). The DTH reactions were induced either by local injection of the helper T cells together with the antigen in the hind feet or by intravenous (iv) administration of the cloned T cells and local injection of the antigen. Local or systemic (oral or iv) administration of mBSA after waning of the DTH induced by the cloned helper T cells caused a flare-up reaction. This indicates that functional helper T cells persist at the inflammation site. The inflammations were quantified in a foot swelling assay and were examined histologically. The inflammation measured in the flare-up reaction was generally lower than in the acute reaction. Histologically the acute inflammation showed edema and a large proportion of granulocytes, whereas the flare-up reaction appeared more histiocytic and showed less edema.     

Changes in the arterial pressure and evoked potential in the sensorimotor cortex induced by nalorphine injected in the hypothalamus during painful electric shock in rabbits

During the hypotensive phase of electronocuous shock in rabbits, injection of nalorphine to the hypothalamus provoked elevation in the blood pressure (BP), recovery of the evoked potential (EP) of the sensorimotor brain cortex in response to electrodermal stimulation (EDS) of the hind limb. Injection of the drug to the central gray of the midbrain resulted in an insignificant short-term elevation of the BP followed by its drop. It is concluded that the endogenous opioid system of the hypothalamus is of importance in the genesis of the hypotensive response and suppression of the EP of the rabbit sensorimotor brain cortex in response to EDS during electronocuous shock.     

Intraplantar injection of glutamate evokes peripheral adenosine release in the rat hind paw: involvement of peripheral ionotropic glutamate receptors and capsaicin-sensitive sensory afferents

Glutamate receptors have been identified on the peripheral terminals of both primary sensory afferents and sympathetic post-ganglionic neurons, and activation of these receptors produces peripheral sensitization and enhances nociception. Adenosine is an endogenous agent that has a regulatory effect on pain. In brain and spinal cord, adenosine release can be promoted by excitatory amino acids. In the present study, we used in vivo microdialysis to determine whether glutamate also can release adenosine in peripheral tissues. Rats were anesthetized with pentobarbital and microdialysis probes were implanted into the subcutaneous tissue of the plantar aspect of the rat hind paw. Subcutaneous injection of glutamate (50 microL, 0.3-100 micromol) evoked a short-lasting adenosine release immediately following drug injection. Co-administration of either the N-methyl-D-aspartate (NMDA) receptor antagonist, dizocipine maleate (MK-801, 1 nmol) or the non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline (CNQX, 10 nmol) with glutamate blocked such release, suggesting an involvement of peripheral ionotropic glutamate receptors in this response. Systemic pre-treatment with capsaicin, a neurotoxin selective for unmyelinated sensory afferents, significantly reduced glutamate-evoked peripheral adenosine release, but release was not affected by systemic pre-treatment with 6-hydroxydopamine, a neurotoxin selective for sympathetic nerve efferents. Neither MK-801 nor CNQX blocked 5% formalin-evoked adenosine release, suggesting adenosine release by formalin is not secondary to ionotropic glutamate receptor activation. We conclude that administration of glutamate evokes peripheral adenosine release, and that peripheral ionotropic glutamate receptors on unmyelinated sensory afferents are involved in such release. The released adenosine may provide a negative feedback control on nociception.     

Role of the kappa-opioid system in the attenuation of the morphine-induced place preference under chronic pain

We previously reported that the morphine-induced place preference was attenuated under inflammation produced by the unilateral injection of 2.5 % formalin (50 microl) into the hind paw of rats. In the present study, to elucidate the mechanism of this attenuation, the effects of pretreatment with delta- and kappa-opioid receptor antagonists, naltrindole (NTI) and nor-binaltorphimine (nor-BNI), on the development of the morphine-induced place preference under inflammation were examined in rats. Nor-BNI, but not NTI, eliminated the suppression of the morphine-induced place preference in inflamed groups. These results suggest that endogenous kappa-opioid systems may be activated in the presence of chronic inflammatory nociception; as a result, the development of morphine's rewarding effect may be suppressed under inflammation.     

Effects of lithium hydroxybutyrate on circadian rhythm of rest-activity and sleep structure in experimental animals]

Lithium hydroxybutyrate (10 mg/kg, 10 days) influences circadian temperature and activity rhythms of rats in "open field" and sleep structure according to the time of preparation of the injection (8.30 or 19.30). It was stated that lithium hydroxybutyrate modified circadian rhythms and sleep structure less after morning injections into the rats, while evening administration destabilized circadian rhythms, increased slow-sleep and decreased REM sleep duration.     

Inflammatory pain alters blood-brain barrier permeability and tight junctional protein expression

Effects of inflammatory pain states on functional and molecular properties of the rat blood-brain barrier (BBB) were investigated. Inflammation was produced by subcutaneous injection of formalin, lambda-carrageenan, or complete Freund's adjuvant (CFA) into the right hind paw. In situ perfusion and Western blot analyses were performed to assess BBB integrity after inflammatory insult. In situ brain perfusion determined that peripheral inflammation significantly increased the uptake of sucrose into the cerebral hemispheres. Capillary depletion and cerebral blood flow analyses indicated the perturbations were due to increased paracellular permeability rather than vascular volume changes. Western blot analyses showed altered tight junctional protein expression during peripheral inflammation. Occludin significantly decreased in the lambda-carrageenan- and CFA-treated groups. Zonula occluden-1 expression was significantly increased in all pain models. Claudin-1 protein expression was present at the BBB and remained unchanged during inflammation. Actin expression was significantly increased in the lambda-carrageenan- and CFA-treated groups. We have shown that inflammatory-mediated pain alters both the functional and molecular properties of the BBB. Inflammatory-induced changes may significantly alter delivery of therapeutic agents to the brain, thus affecting dosing regimens during chronic pain.     

Effect of sodium hydroxybutyrate on cerebral circulation and regional vasomotor reflexes

In experiments on cats it was found using electromagnetic and resistographic methods that sodium hydroxybutyrate (100 mg/kg) considerably increases cerebral circulation. The drug also potentiates the blood flow to the brain during formation of pressor reflexes of the arterial pressure. The blood flow increase is also observed in the system of femoral arteries while in the intestinal artery, on the contrary, there is a reduction in the blood flow increase during vasomotor reflexes. The reflex changes of the resistance in regional vessels are also different: the inhibition of pressor reflexes in the cerebral vessels along with their facilitation in the intestinal and femoral arteries and the potentiation of the reflex dilatatory phase in the limb vessels are seen. Different sensitivity to the drug of synaptic formations in the central links of various regional vasomotor reflexes is likely to underlie the difference described.     

Tempol modulates changes in xenobiotic permeability and occludin oligomeric assemblies at the blood-brain barrier during inflammatory pain

Our laboratory has shown that λ-carrageenan-induced peripheral inflammatory pain (CIP) can alter tight junction (TJ) protein expression and/or assembly leading to changes in blood-brain barrier xenobiotic permeability. However, the role of reactive oxygen species (ROS) and subsequent oxidative stress during CIP is unknown. ROS (i.e., superoxide) are known to cause cellular damage in response to pain/inflammation. Therefore, we examined oxidative stress-associated effects at the blood-brain barrier (BBB) in CIP rats. During CIP, increased staining of nitrosylated proteins was detected in hind paw tissue and enhanced presence of protein adducts containing 3-nitrotyrosine occurred at two molecular weights (i.e., 85 and 44 kDa) in brain microvessels. Tempol, a pharmacological ROS scavenger, attenuated formation of 3-nitrotyrosine-containing proteins in both the hind paw and in brain microvessels when administered 10 min before footpad injection of λ-carrageenan. Similarly, CIP increased 4-hydroxynoneal staining in brain microvessels and this effect was reduced by tempol. Brain permeability to [(14)C]sucrose and [(3)H]codeine was increased, and oligomeric assemblies of occludin, a critical TJ protein, were altered after 3 h CIP. Tempol attenuated both [(14)C]sucrose and [(3)H]codeine brain uptake as well as protected occludin oligomers from disruption in CIP animals, suggesting that ROS production/oxidative stress is involved in modulating BBB functional integrity during pain/inflammation. Interestingly, tempol administration reduced codeine analgesia in CIP animals, indicating that oxidative stress during pain/inflammation may affect opioid delivery to the brain and subsequent efficacy. Taken together, our data show for the first time that ROS pharmacological scavenging is a viable approach for maintaining BBB integrity and controlling central nervous system drug delivery during acute inflammatory pain.