Search

A comparative experimental analysis of intensity of nitric oxide (NO) production and the copper content in the tissues of hippocampus of male Wistar rats after modeling of hemorrhagic stroke and brain injury was conducted using EPR spectroscopy. Modeling of hemorrhagic stroke was carried out by microinjection of 500 nl of autologous blood into the brain to a depth of 5.0 mm (hippocampus) on the left side. Brain injury was performed by removing a piece of nerve tissue from 5.0 mm depth on the left side of hippocampus. It was registered a significant decrease in the NO content in hippocampus by 36 ± 17% on the 3rd day after modeling of hemorrhagic stroke together with decrease by an average of 24 ± 14% of the copper content. There were no significant changes in the NO level in hippocampus found neither on the 3rd day nor on the 7th day after brain injury modeling. There was also no change in copper content. Thus, it was experimentally demonstrated that modeling of brain injury, in contrast to hypoxia induced by hemorrhagic stroke, was not accompanied with significant changes in NO production in hippocampus of rat.

In order to simulate apoptotic processes in the central nervous system and retina, one eyeball was enucleated in each of the male Wistar rats (n = 10) aged 10–12 weeks. Simultaneously, in one of the series of experiments (n = 5), 100 000 PKH67-labeled mesenchymal stem cells (MSCs) in 100 µL of buffer solution were injected parabulbarically on the side of an intact eye. In another series of experiments on rats (n = 5), immediately after enucleation, on one side of the eye, 100 000 PKH67-labeled MSCs in 100 µL of buffer solution were injected intranasally into the upper part of the nasal cavity. Three days after enucleation, brain and retinal slices were prepared on a cryostat. In both series of experiments, the distribution of fluorescent MSCs was determined in the mesencephalic quadruplet bodies, diencephalic lateral geniculate body, and intact eye’s retina. It was inferred that intranasal perineural implantation of MSCs, due to its simplicity and efficiency, is a promising alternative method of MSC delivery into the retina of patients with signs of dystrophic and degenerative processes.

Relevance. The problem of effective prevention and treatment of traumatic brain injuries (TBI) of various etiologies has not been resolved in all countries of the world. Primary brain damage from trauma initiates secondary damage to the nervous tissue. As a result, the interaction of brain neural networks is disrupted and the control of somatic and visceral functions of the body is weakened. The article is based on our own clinical observations and comparison of results with literature data and provides a discussion of the prospects for the use of cell technologies in the prevention of fatal disorders of vital functions control in traumatic brain injuries. Objective. To evaluate the effectiveness of intranasal perineural implantation of mesenchymal stem cells (MSCs) in the complex therapy of patients with TBI. Materials and methods. The technique intranasal perineural administration of MSCs was used in complex therapy of 15 patients with severe TBI. The patients were 19÷69 years old, 13 men and two women. A cell suspension was isolated from the adipose tissue of the patient's abdominal wall and centrifuged for 10 min at 1500 rpm. The cell pellet was washed in phosphate buffered saline and DMEM. Cells were cultured in plastic culture flasks in a humidified atmosphere with 5% CO2 content. The cell mass was trypsinized according to standard technique and resuspended in physiological saline on the day of implantation. Dynamics of culture growth, pluripotency, phenotyping of MSCs were monitored. MSCs were injected under general anesthesia into the submucosa of the nasal cavity 3-4 times with an interval of 3-7 days, depending on the growth rate of MSCs, in a single dose from 12.0×106 to 35.0×106 cells. Results. The use of allogeneic and predominantly autologous MSCs of adipose tissue in the complex treatment of patients with severe TBI by intranasal perineural delivery to the area of traumatic brain injury does not cause complications and is a safe technique. 8 patients with severe TBI showed from 4 to 7 points according to the Glasgow Outcome Scale Extended, with an average of 5.4±1.1 points after 6 months. The main result is that complex therapy, including intranasal implantation of MSCs in acute and subacute periods of severe TBI, contributes to the survival of patients and restoration of neurological – including cognitive – functions control. Conclusions. The effectiveness of intranasal perineural implantation of MSCs in the complex therapy of patients with TBI has been demonstrated. The mechanisms of the beneficial effects of perineural implantation of MSCs in patients with TBI require further research.

Chemotherapy is one of the main treatment options for cancer, but it is usually accompanied with negative side effects. The classical drugs combination with synergistic adjuvants can be the solution to this problem, allowing reducing therapeutic dose. Elucidating the mechanism of adjuvant action is of key importance for selection of the optimal agent. Here we examine the system drug-adjuvant to explain observed effect in practice. We used the first line drug – cisplatin. Morpholinium and 4-methylpiperazinium 4,5-dichloro isothiazol-3-carboxylates were selected as adjuvants. The study of cisplatin – adjuvant system was carried out by quantum chemical modeling with DFT method. It turned out that adjuvants form conjugates with cisplatin that leads to relocation of frontier molecular orbitals as well as increase of conjugate’s dipole moment. It results in change of the character of interaction with DNA and increase of bioactivity of system. The data obtained are the basis for expanding the studies to include other drugs and adjuvants. Oncologists will have opportunity to use “classical” chemotherapy drugs in combination with synergists for those patients who have not been previously recommended to such treatment because of pronounced toxic side effects.

Results of analysis of nitric oxide and copper content in rat liver and hippocampus after brain ischemia modeling are provided. The studies are carried out using the electron paramagnetic resonance spectroscopy method with spin traps. It was shown that, the day after brain ischemia modeling, nitric oxide content in hippocampus decreases on average by 50% and a tendency toward its decrease was observed in liver tissues. Two days after brain ischemia modeling, nitric oxide content in the brain recovered and a significant increase by 46% against control indices was observed in the liver. On the second day of the postischemic period, the copper content, which is associated with superoxide dismutase content, increased on average by 2.5-fold in the liver. No significant changes in copper content was found in the hippocampus.

A comparative experimental analysis by EPR spectroscopy of the intensity of nitric oxide (NO) production and the content of the copper in the tissues of olfactory bulb of the brain of male Wistar rats were performed after modeling of ischemic stroke and treatment with immediate intranasal injection of mesenchymal stem cells (MSCs). Brain ischemia was simulated by ligation at the level of bifurcation of the common carotid arteries. It was found a significant reduction of NO content in the olfactory bulb of the brain of rats on the 1st and 2nd days after modeling of ischemia. The level of NO production was also reduced on the 1st and 2nd days after ischemia with MSCs’ administration as compared to intact animals. It was not found the significant difference of the NO content in rats after ischemia with MSCs’ administration relative to ischemic rats. The copper content in the olfactory bulb of the rat, which corresponds to the level of superoxide dismutase 1 and 3, tended to increase after modeling ischemia and remained for 2 days. The MSCs’ administration was accompanied by a significant increase in copper content on the 1st day after modeling of ischemia and by decrease of its content on 2nd day after ischemia. The experiments showed that MSCs’ administration did not affect the intensity of NO production on the 1st and 2nd days after the modeling of brain ischemia, but was accompanied by an increase in the antioxidant protection of the nervous tissue 1 day after ischemia.

It was shown by electron paramagnetic resonance (EPR) spectroscopy that one day after bilateral occlusion of the common carotid arteries (to simulate ischemia) in Wistar rats (group 1, n = 15) under ketamine-xylazine-acepromazine anesthesia (55.6, 5.5, 1.1 mg/kg, respectively, intraperitoneally), the content of nitric monoxide (NO) in the olfactory bulbs decreased, and recovered after two days. A similar trend was observed in Wistar rats (group 2, n = 15), which, simultaneously with ischemia modeling, were implanted intranasally with mesenchymal stem cells (MSCs). An intact group of rats (group 3, n = 15) was kept in the usual conditions of the vivarium and did not undergo surgical interventions. The content of copper in the olfactory bulbs of rats (for assessing the activity of superoxide dismutases 1 and 3) after ischemia modeling (group 1) tended to increase and maintain the increase for two days of observation. Intranasal administration of MSCs during the ischemia modeling was accompanied by a more significant increase in copper content on the first day after brain ischemia modeling, but after two days, a tendency towards restoration of the initial copper level was noted.

Non-small cell lung cancer (NSCLC) cells of a specific patient N have been analyzed to determine sensitivity to cisplatin. Intraoperative material was examined under sterile conditions in a culture box after pre-treatment of tissue pieces from the primary NSCLC tumor and from metastases to the lymph nodes of lung root. NSCLC tumor cells were cultivated in vials for four days and then in 24 well plates with and without cisplatin at different dosages (150.0 μg, 15.0 μg, 1.5 μg per well). High resistance of NSCLC tumor cells of patient N from the lymph nodes of lung root to cisplatin was established using an automatic enzyme immunoassay analyzer in 24 hours. In comparison with this fact, NSCLC tumor cells from the tissue of primary were killed by cisplatin. Obtained facts are the basis for considering the use of one of chemotherapy drugs recommended by international protocols (atezolizumab, ceritinib, osimertinib, and pembrolizumab) instead of cisplatin in patient N.

Experiments were performed on 28 sexually mature Wistar rats divided into two equal groups. Rats were fixed in stereotactic apparatus and received 2.8×105 C6 glioma cells in 20 μl of F10 medium locally into frontal region of brain under ketamine-xylazine-acepromazine anesthesia. One group of rats (n=14) was implanted with 40×104 MSCs in 40 μl of low glucose DMEM medium into submucosa of nasal cavity. Further, only rats from this group received 40×104 mesenchymal stem cells (MSCs) intranasally in the form of a spray on a weekly basis. All 14 rats from the second group died within two months. Rats with implanted MSCs started to die in two and a half months. Two rats lived up to 8.5 months. One of these rats was decapitated, brain slices stained with hematoxylin-eosin and Nissl – and no tumor cells were found. A connective tissue scar was found at the site of injection.

Medical devices are used for diagnosis and prevention [1,2], therapy [2,3], rehabilitation of patients, and depending on the purpose, require sterilization in accordance with related regulations...

Electron paramagnetic resonance (EPR) was used as a method to record nitric oxide (NO) production in the tissues of the brain, heart and liver of healthy rats, and rats after modeling of ischemic stroke. Direct measurement of the dynamics of NO production by EPR spectroscopy in our experiments showed that after the emergence of signs of ischemic stroke, 5 h after the start of ischemia, the content of NO in the hippocampus decreased two- to threefold and this decrease was maintained at 24 and 72 h. Deserving special attention is the data demonstrating that there is a greater decrease of NO production in the tissues of the heart and liver than in the brain. Consequently, the change in intensity of NO production in the modeling of ischemic events in the brain has a systemic, not a local character.

International audience

Reactions of 4,5-dichloroisothiazol-3-ylcarbonitrile with methylmagnesium iodide and ethylmagnesium bromide afforded the corresponding alkyl (4,5-dichloroisothiazol-3-yl) ketones. The reaction of (4,5-dichloroisothiazol-3-yl) methyl ketone with morpholine and piperidine provided 5-morpholino-(piperidino)-substituted derivatives, by the action of sodium borohydride in 2-propanol the keto group was reduced to alcoholic hydroxy group. The bromination of (4,5-dichloroisothiazol-3-yl) methyl ketone with elemental bromine gave bromomethyl (4,5-dichloroisothiazol-3-yl) ketone, whose reaction with thiourea resulted in 2-amino-4-(4,5-dichloroisothiazol-3-yl)thiazole.

Deep body temperature of 57 male Wistar rats was measured in response to systemic (i.v. or i.p.) injection of Escherichia coli lipopolysaccharide (LPS). Animals were preliminarily (4 weeks before the experiment) treated with microinjections of the toxic dose of glutamate receptors agonists or vehicle into solitary tract nucleus or caudal part of ventrolateral medulla. Microinjections of the glutamate receptors agonists provoked a local destruction of brain tissue, which was accompanied by the significant transformation (amplification or attenuation) of temperature response to the systemic injection of 3 μg/kg E. coli LPS. Animals treated with vehicle did not demonstrate significant changes in their response to LPS. Obtained data testify that impairment of central nervous structure involved in the regulation and maintenance of deep body temperature is accompanied by atypical development of E. coli LPS-induced fever.

Dry immersion is an effective and useful model for research in physiology and physiopathology. The focus of this study was to provide integrative insight into renal, endocrine, circulatory, autonomic and metabolic effects of dry immersion. We assessed if the principal changes were restored within 24 h of recovery, and determined which changes were mainly associated with immersion-induced orthostatic intolerance. Five-day dry immersion without countermeasures, and with ad libitum water intake, standardized diet and a permitted short daily rise was performed in a relatively large sample for this experiment type (14 healthy young men). Reduction of total body water derived mostly from extracellular compartment, and stabilized rapidly at the new operating point. Decrease in plasma volume was estimated at 20% - 25%. Five-day immersion was sufficient to impair metabolism with a decrease in glucose tolerance and hypercholesterolemia, but was not associated with pronounced autonomic changes. Five-day immersion induced marked cardiovascular impairment. Immediately after immersion, over half of the subjects were unable to accomplish the 20-min 70° tilt; during tilt, heart rate and total peripheral resistance were increased, and stroke volume was decreased. However, 24 hours of normal physical activity appeared sufficient to reverse orthostatic tolerance and all signs of cardiovascular impairment, and to restitute plasma volume and extracellular fluid volume. Similarly, metabolic impairment was restored. In our study, the major factor responsible for orthostatic intolerance appeared to be hypovolemia. The absence of pronounced autonomic dysfunction might be explained by relatively short duration of dry immersion and daily short-time orthostatic stimulation.

Research concerning new targeting delivery systems for pharmacologically active molecules and genetic material is of great importance. The aim of the present study was to investigate the potential of fourth generation (P4) cationic phosphorus-containing dendrimers to bind fluorescent probe 8-anilino-1-naphthalenesulfonate (ANS), anti-neoplastic drug cisplatin, anti-HIV siRNA siP24 and its capability to deliver green fluorescent protein gene (pGFP) into cells. The interaction between P4 and ANS (as the model drug) was investigated. The binding constant and the number of binding centers per one molecule of P4 were determined. In addition, the dendriplex between P4 and anti-HIV siRNA siP24 was characterized using circular dichroism, fluorescence polarization and zeta-potential methods; the average hydrodynamic diameter of the dendriplex was calculated using zeta-size measurements. The efficiency of transfection of pGFP using P4 was determined in HEK293 cells and human mesenchymal stem cells, and the cytotoxicity of the P4-pGFP dendriplex was studied. Furthermore, enhancement of the toxic action of the anti-neoplastic drug cisplatin by P4 dendrimers was estimated. Based on the results, the fourth generation cationic phosphorus-containing dendrimers seem to be a good drug and gene delivery carrier candidate.

Immersion is a useful tool for studying fluid-volume homeostasis. Natriuretic peptides play a vital role in renal, humoral, and cardiovascular regulation under changing environmental conditions. We hypothesized that dry immersion would rapidly induce a new steady state for water and sodium metabolism, and that serum NT-proBNP levels, a proxy measure for brain natriuretic peptide (BNP), would decrease during long-term dry immersion and increase during recovery. Eight healthy young men were studied before, during, and after 7 days of dry immersion. Body weight, water balance, and plasma volume changes were evaluated. Plasma and serum samples were analyzed for active renin, NT-proBNP, aldosterone, electrolytes, osmolality, total protein, and creatinine. Urine samples were analyzed to determine levels of electrolytes, osmolality, creatinine, and free cortisol. A stand test was performed before and after dry immersion to evaluate cardiovascular deconditioning. Long-term dry immersion induced acute changes in water and sodium homeostasis on day 1, followed by a new steady state. Plasma volume decreased significantly during dry immersion. The serum levels of NT-proBNP increased significantly in recovery (10 ± 3 ng/L before dry immersion vs. 26 ± 5 ng/L on the fourth recovery day). Heart rate in the standing position was significantly greater after immersion. Results suggest that chronic dry immersion rapidly induced a new level of water-electrolyte homeostasis. The increase in NT-proBNP levels during the recovery period may be related to greater cardiac work and might reflect the degree of cardiovascular deconditioning.

Methyl 5-hydroxy-4-oxo-4 H-pyran-2-carboxylate was synthesized by esterification of methanol with comenic acid under acidic catalysis. The obtained ester was alkylated with 3-(chloromethyl)-5-phenylisoxazole and 4,5-dichloro-3-(chloromethyl)isothiazole to afford corresponding conjugates containing isoxazole and isothiazole moieties which then were transformed into water-soluble Li-salts. During the bioassays of synthesized isoxazole and isothiazole derivatives of comenic acid in mixtures with first-line antitumor drug Temobel (Temozolomid) used in brain tumors chemotherapy, a synergetic effect was observed.

The survival of rat C6 glioma decreased in the presence of implants from VT-16 titanium alloy. Diamond-like carbon coating of VT-16 alloy slightly increased cell death on day 5 of the experiment (39.9+/-2.1%). The percentage of dead C6 glioma cells inside titanium rings with diamond-like carbon coating, incorporating up to 3.5 atom.% Ag nanoparticles, was 53.7+/-4.3% on day 5 of culturing, while after doping to 6.7 atom.% Ag cell death reached 66.7+/-3.2% (p0.05). The maximum toxic effect towards C6 glioma was detected in the specimens coated with diamond-like film with silver nanoparticles.

The technique of combined DC metal arc and carbon pulsed arc was used to deposit thin solid films containing up to 6.5 at.% of silver. The microstructure and antibacterial properties of silver-doped diamond-like carbon (DLC) films have been investigated. Silver nanoparticle of flat disk shape located inside of an amorphous carbon matrix revealed excellent antibacterial properties concerning Staphylococcus аureus bacteria. Titanium substrates with DLC films doped with silver have an inhibiting effect on growth of some tumors, in particular, on rat neoplastic С6 glioma. This result is new and opens further possibility for application of DLC:Ag composite in medicine.

Ongoing activity of spinal trigeminal neurons is observed under various conditions and suggested to be responsible for ongoing headache. It can be spontaneous, i.e. arising intrinsically from the neuron, or the product of descending influences from other central neurons, or maintained by ongoing afferent input. The aim of the present study was to examine if ongoing activity of neurons in different subnuclei of the spinal trigeminal nucleus is driven from peripheral afferent input. Experiments were performed in Wistar rats anesthetized with isoflurane or Nembutal/urethane. Ongoing activity of single wide-dynamic range (WDR) neurons was recorded with carbon fiber glass microelectrodes in two subnuclei of the spinal trigeminal nucleus: oral (Sp5O) and caudal (Sp5C). Peripheral receptive fields were evaluated using von Frey filaments. Sp5O neurons received peripheral input from facial areas innervated by the mandibular branch of the trigeminal nerve. Units in Sp5C had receptive fields in the surgically exposed dura mater and in facial areas innervated by the ophthalmic and maxillary branch of the trigeminal nerve. Saline or the local anesthetic lidocaine was locally applied onto the exposed dura mater or microinjected into V3 (for Sp5O units) or V1/V2 (for Sp5C units) divisions of the trigeminal ganglion via the infraorbital channel. Local application of lidocaine onto the exposed dura caused mechanical insensitivity of dural receptive fields but not significant decrease in ongoing activity. Microinjection of lidocaine but not saline into the trigeminal ganglion was followed by a substantial decrease in both the receptive field size and the activity of the recorded WDR units. Mechanical insensitivity of receptive fields after trigeminal ganglion blockade was accompanied by the disappearance of ongoing activity. We conclude that the ongoing activity of WDR neurons in the spinal trigeminal nucleus, which may be indicative for processes of sensitization, is driven remotely by ongoing afferent input.

Lipopolysaccharide (LPS)-induced systemic inflammation is accompanied by either hypothermia (prevails when the ambient temperature (Ta) is subneutral) or fever (prevails when Ta is neutral or higher). Because platelet-activating factor (PAF) is a proximal mediator of LPS inflammation, it should mediate both thermoregulatory responses to LPS. That PAF possesses hypothermic activity and mediates LPS-induced hypothermia is known. We asked whether PAF possesses pyrogenic activity (Expt 1) and mediates LPS fever (Expt 2). The study was conducted in Long-Evans rats implanted with jugular catheters. A complex with bovine serum albumin (BSA) was infused as a physiologically relevant form of PAF; free (aggregated) PAF was used as a control. In Expt 1, either form of PAF caused hypothermia when infused (83 pmol kg-1 min-1, 60 min, i.v.) at a subneutral Ta of 20 degrees C, but the response to the PAF-BSA complex (-4.5 +/- 0.5 degrees C, nadir) was ~4 times larger than that to free PAF. At a neutral Ta of 30 degrees C, both forms caused fever preceded by tail skin vasoconstriction, but the febrile response to PAF-BSA (1.0 +/- 0.1 degrees C, peak) was2 times higher than that to free PAF. Both the hypothermic (at 20 degrees C) and febrile (at 30 degrees C) responses to PAF-BSA started when the total amount of PAF infused was extremely small,830 pmol kg-1. In Expt 2 (conducted at 30 degrees C), the PAF receptor antagonist BN 52021 (29 micromol kg-1, i.v.) had no thermal effect of itself. However, it strongly (~2 times) attenuated the febrile response to PAF (5 nmol kg-1, i.v.), implying that this response involves the PAF receptor and is not due to a detergent-like effect of PAF on cell membranes. BN 52021 (but not its vehicle) was similarly effective in attenuating LPS (10 microg kg-1, i.v.) fever. It is concluded that PAF is a highly potent endogenous pyrogenic substance and a mediator of LPS fever.

The involvement of the cholecystokinin (CCK)-A receptor in fever was studied. The polyphasic febrile responses to lipopolysaccharide (LPS; 10 microg kg-1, I.V.) were compared between wild-type Long-Evans (LE) rats and the CCK-A-receptor-deficient Otsuka LE Tokushima Fatty (OLETF) rats. The response of the wild-type rats was biphasic, which is typical for LE rats. Phases 1 and 2 of the response of the OLETF rats were similar to those of the LE rats, but the OLETF rats also developed a robust phase 3. This late enhancement of the febrile response could reflect either the absence of the A receptor per se or a secondary trait of the mutant strain. To distinguish between these possibilities, we conducted a pharmacological analysis. We studied whether the normally low phase 3 of LE rats can be enhanced by a CCK-A-receptor antagonist, sodium lorglumide (4.3 microg kg-1 min-1, 120 min, I.V.), and whether the normally high phase 3 of Wistar rats can be attenuated by a CCK-A receptor agonist, sulphated CCK-8 (up to 0.17 microg kg-1 min-1, 120 min, I.V.). The dose of sodium lorglumide used was sufficient to increase food intake (to block satiety), but it did not affect the fever response. In both febrile and afebrile rats, CCK-8 induced dose-dependent skin vasodilatation and decreased body temperature, but it failed to produce any effects specific for phase 3. We conclude that the exaggeration of phase 3 in OLETF rats reflects a secondary trait of this strain and not the lack of the CCK-A receptor per se. None of the three known phases of the febrile response of rats to LPS requires the CCK-A receptor.

BACKGROUND AND OBJECTIVE: A decreased resistance to infection and impairments of immunity are common in obese humans and in rodents with hereditary obesity. Since brown fat thermogenesis is also suppressed in obese rodents, we hypothesized that obesity leads to a decreased febrile responsiveness. METHODS: We compared the fever responses to intravenous E. coli lipopolysaccharide (10 µg/kg) between Zucker fa/fa (obese due to a defective leptin receptor) and Fa/? (lean) rats and between Otsuka Long–Evans Tokushima Fatty (OLETF; obese due to the lacking cholecystokinin-A receptor) and Long-Evans Tokushima Otsuka (lean) rats. Obesity of Zucker fa/fa and OLETF rats was verified by increased body mass and fat content, hypertriglyceridemia and hypercholesterolemia. RESULTS: Neither fa/fa nor OLETF animals exhibited a decreased febrile responsiveness; if anything, their fevers tended to be higher than those in their lean counterparts. CONCLUSION: Obesity per se does not lead to antipyresis. International Journal of Obesity (2001) 25, 586–589

In rats, fevers induced by moderate-to-high doses of intravenous lipopolysaccharide consist of three phases (phases 1, 2 and 3) with body temperature peaks at approximately 1, 2, and 5 h postinjection, respectively. In this study, the effects of bilateral truncal subdiaphragmatic vagotomy and intraperitoneal capsaicin desensitization on febrile phases 1-3 were assessed in adult Wistar rats. Surgical vagotomy was performed approximately 30 d before the experiment; this procedure interrupts both afferent and efferent vagal fibers. Capsaicin was administered intraperitoneally in two consecutive injections (2 and 3 mg/kg, 3 h apart) 1 week prior to the experiment; this procedure desensitizes afferent fibers, primarily within the abdominal cavity, and does not lead to the known thermal effects of systemic capsaicin desensitization. At a neutral ambient temperature, the rats were given Escherichia coli lipopolysaccharide (10 microg/kg) through a preimplanted jugular catheter, and their colonic temperature wes measured by thermocouples for 7 h. The control rats exhibited the typical triphasic febrile responses. Confirming our earlier studies, subdiaphragmatic vagotomy did not affect phases 1 and 2; it did, however, result in a 2.5-fold reduction of phase 3. Capsaicin desensitization modified the febrile response differently: phases 2 and 3 were unaffected, but phase 1 disappeared. We suggest that neural afferent fibers (nonvagal but perhaps vagal as well) play an important role in the early febrile response (phase 1) by transducing peripheral pyrogenic signals to the brain. We also suggest that vagal efferent fibers are likely to participate in the later febrile response (phase 3) via an unknown mechanism.

Subdiaphragmatic vagotomy decreases the febrile responsiveness to intraperitoneal (i.p.) lipopolysaccharide (LPS), but whether this effect is due to interruption of afferent or efferent vagal fibers remains unknown. To address this issue, we injected LPS (10 μg/kg, i.p.) in four groups of rats: (i) subdiaphragmatically vagotomized at the trunk level; (ii) sham-vagotomized; (iii) selectively de-efferented (via combined right efferent rhizotomy and anterior gastroceliac branch vagotomy); and (iv) sham-de-efferented. The febrile response in both groups (i) and (iii) was attenuated two-fold as compared to groups (ii) and (iv), respectively. We suggest that motor vagal fibers may be involved in fever genesis, perhaps by interfering with LPS transport from the peritoneal cavity to the blood.

Experiments on hippocampal slices form 4-week-old rats (n=28) showed that addition of lidase (1.0 and 10.0 U/ml) to the perfusion solution (artificial cerebrospinal fluid) was accompanied by the impaired generation or blockade of excitatory postsynaptic potentials and population spikes in the hippocampal CA1 region during stimulation of Schaffer collaterals. Removal of lidase from this solution normalized the amplitude of evoked responses. Hence, lidase in these concentrations produced a reversible effect on synaptic transmission. Our results indicate that structure and function of glycosaminoglycans in the extracellular matrix determine signal transduction in the nervous tissue.

Recent evidence has suggested a role of abdominal vagal afferents in the pathogenesis of the febrile response. The abdominal vagus consists of five main branches (viz., the anterior and posterior celiac branches, anterior and posterior gastric branches, and hepatic branch). The branch responsible for transducing a pyrogenic signal from the periphery to the brain has not as yet been identified. In the present study, we address this issue by testing the febrile responsiveness of male Wistar rats subjected to one of four selective vagotomies: celiac (CBV), gastric (GBV), hepatic (HBV), or sham (SV). In the case of CBV, GBV, and HBV, only the particular vagal branch(es) was cut; for SV, all branches were left intact. After the postsurgical recovery (26–29 days), the rats had a catheter implanted into the jugular vein. On days 29–32, their colonic temperature (Tc) responses to a low dose (1 μg/kg) of Escherichia colilipopolysaccharide (LPS) were studied. Three days later, the animals were subjected to a 24-h food and water deprivation, and the effectiveness of the four vagotomies to induce gastric food retention, pancreatic hypertrophy, and impairment of the portorenal osmotic reflex was assessed by weighing the stomach and pancreas and measuring the specific gravity of bladder urine, respectively. Stomach mass, pancreas mass, and urine density successfully separated the four experimental groups into four distinct clusters, thus confirming that each type of vagotomy had a different effect on the indexes measured. The Tc responses of SV, CBV, and GBV rats to LPS did not differ and were characterized by a latency of ∼40 min and a maximal rise of 0.7 ± 0.1, 0.6 ± 0.1, and 0.9 ± 0.2°C, respectively. The fever response of the HBV rats was different; practically no Tc rise occurred (0.1 ± 0.2°C). The HBV appeared to be the only selective abdominal vagotomy affecting the febrile responsiveness. We conclude, therefore, that the hepatic vagus plays an important role in the transduction of a pyrogenic signal from the periphery to the brain.

This paper disproves the common belief that all doses of lipopolysaccharide (LPS) that are commonly referred to as biphasic fever inducing (≥2 μg/kg) cause truly biphasic responses. A catheter was implanted into the right jugular vein of several strains of adult male rats, and the animals were habituated to the experimental conditions. At an ambient temperature of 30.0°C, loosely restrained animals were injected with a 10 μg/kg dose of LPS (various preparations), and their colonic (Tc) and tail skin temperatures were monitored (from ≥1 h before to ≥7 h after the injection). The results are presented as time graphs and phase-plane plots; in the latter case the rate of change of Tc is plotted against Tc. In experiment 1 the intravenous injection of LPS (from Escherichia coli 0111:B4, phenol extract) into the rats (Bkl:Wistar) induced a triphasic febrile response, as is obvious from time graphs of Tc (3 peaks), time graphs of effector activity (3 waves of tail skin vasoconstriction), and phase-plane plots (3 complete loops); the injection of saline (control) induced no Tc changes. We analyzed whether the triphasic pattern was due to some peculiarities of the experimental design, i.e., the pyrogen preparation used ( experiment 2) or the rat strain tested ( experiment 3) or whether this pattern reflects a more general law. In experiment 2 we used the same (phenol) preparation of different LPS (from Shigella flexneri 1A and Salmonella typhosa) and a different preparation (TCA extract) of the same LPS ( E. coli). Regardless of the LPS used, rats of the Bkl:Wistar strain responded to the 10 μg/kg dose with the triphasic fever. In experiment 3, rats of other strains [Bkl:Sprague-Dawley and Sim:(LE)fBR(Black-hooded)] were tested. Again, all animals responded to the 10 μg/kg dose of E. coli LPS (phenol extract) with the triphasic fever. Because all fevers caused by four different LPS preparations in three rat strains were triphasic, the triphasic pattern is likely to constitute an intrinsic characteristic of the febrile response.

This study explains why the recently described triphasic lipopolysaccharide (LPS) fevers have been repeatedly mistaken for biphasic fevers. Experiments were performed in loosely restrained male Wistar rats with a catheter implanted into the right jugular vein. Each animal was injected with Escherichia coli LPS, and its colonic (Tc) and tail skin temperatures were monitored. The results are presented as time graphs and phase-plane plots; in the latter case the rate of change of Tc is plotted against Tc. At an ambient temperature (Ta) of 30.0°C, the response to the 10 μg/kg dose of LPS was triphasic, as is obvious from time graphs of Tc (3 peaks), time graphs of effector activity (3 waves of tail skin vasoconstriction), and phase-plane plots (3 complete loops). When the Ta was below neutral (22.0°C) or the LPS dose was higher (100 or 1,000 μg/kg), the time graph of Tc did not allow for the reliable detection of all three febrile phases, but the phase-plane plot and time graph of effector activity clearly revealed the triphasic pattern. In a separate experiment, LPS (10 μg/kg) or saline was injected via one of two different procedures: in the first group the injection was performed through the jugular catheter, from outside the experimental chamber; in the second group the same nonstressing injection was combined with opening the chamber and pricking the animal in its lower abdomen with a needle. In the first group the febrile response was obviously triphasic, and none of the phases was due to the procedure of injection per se (injection of saline did not affect Tc). In the second group the fever similarly consisted of three Tc rises, but it might have been readily mistaken for biphasic because the first rise was indistinguishable from stress hyperthermia occurring in the saline-injected (and needle-pricked) controls. We conclude that several methodological factors (dose of LPS, procedure of its injection, and Ta) have contributed, although each in a different way, to the common misbelief that there are only two febrile phases.

Subdiaphragmatically vagotomized rats cannot mount a febrile response to pyrogens and are believed to have severe thermoregulatory deficiencies. We addressed the issue of thermoeffector competence of vagotomized rats by asking three questions. In Expt. 1 we asked, can vagotomized rats readily recruit tail skin vasoconstriction in the course of a moderate cold exposure? In Expt. 2 the question was, can brown adipose tissue (BAT) thermogenesis readily be activated in vagotomized rats (e.g., in response to a tail pinch)? In Expt. 3, we investigated the question: can vagotomized rats elevate their body temperature in response to ephedrine (a drug of high hyperthermizing potential) to the same extent as sham-operated controls? Rats were vagotomized or sham operated and implanted with a catheter into the jugular vein and a thermocouple into the interscapular BAT. To prevent the common complications of vagotomy, special perioperative care was given. During experiments, colonic, tail skin, and BAT temperatures (Tc, Tsk, and TBAT, respectively) were measured. The vagotomized animals were well nourished and had a body mass (325 +/- 6 g) similar to that of the controls (338 +/- 6 g). In Expt. 1, in response to external cooling (15 degrees C, 1 h), the vagotomized (n = 30) and sham-operated (n = 31) rats recruited tail skin vasoconstriction at close values of both Tc (37.84 +/- 0.08 and 37.97 +/- 0.07 degrees C) and Tsk (33.16 +/- 0.17 and 33.18 +/- 0.18 degrees C, respectively). In Expt. 2, tail pinch-associated stress in vagotomized rats resulted in a sharp rise in the TBAT-Tc gradient by 0.3-1.0 degree C. In Expt. 3, ephedrine administered intravenously (whether in a 5 or 35 mg/kg dose) evoked similar hyperthermic responses in the vagotomized and sham-operated rats: a moderate (approximately 2.5 degrees C) Tc rise in the low dose and a "supramaximal" (approximately 5.0 degrees C) rise in the high dose. In sum, the answer to all three questions asked is yes. Vagotomized rats, at least when well nourished, exhibit no signs of thermoeffector deficiency. It is, therefore, not effector incompetence but rather vagal deafferentation per se that can explain the febrile irresponsiveness of vagotomized rats.