TRPV1-mediated Pharmacological Hypothermia Promotes Improved Functional Recovery Following Ischemic Stroke

Hypothermia shows promise for stroke neuroprotection, but current cooling strategies cause undesirable side effects that limit their clinical applications. Increasing efforts have focused on pharmacological hypothermia as a treatment option for stroke. Previously, we showed that activation of a thermoregulatory ion channel, transient receptor potential vanilloid 1 (TRPV1), by dihydrocapsaicin (DHC) produces reliable hypothermia. In this study, we investigate the effects of TRPV1-mediated hypothermia by DHC on long-term ischemic stroke injury and functional outcome. Hypothermia initiated at 3.5 hours after stroke significantly reduced primary cortical injury. Interestingly, hypothermia by DHC also significantly reduced secondary thalamic injury, as DHC-treated stroke mice exhibited 53% smaller thalamic lesion size. DHC-treated stroke mice further demonstrated decreased neuronal loss and astrogliosis in the thalamus and less thalamic fiber loss by diffusion tensor imaging (DTI). Importantly, a single 8 hour treatment of hypothermia by DHC after stroke provided long-term improvement in functional outcome, as DHC-treated mice exhibited improved behavioral recovery at one month post-stroke. These findings indicate that TRPV1-mediated hypothermia is effective in reducing both primary cortical injury and remote secondary thalamic injury, and a single treatment can produce persistent effects on functional recovery. These data highlight the therapeutic potential for TRPV1 agonism for stroke treatment.

Dihydrocapsaicin (DHC) enhances the hypothermia-induced neuroprotection following ischemic stroke via PI3K/Akt regulation in rat

OBJECTIVE

Hypothermia has demonstrated neuroprotection following ischemia in preclinical studies while its clinical application is still very limited. The aim of this study was to explore whether combining local hypothermia in ischemic territory achieved by intra-arterial cold infusions (IACIs) with pharmacologically induced hypothermia enhances therapeutic outcomes, as well as the underlying mechanism.

METHODS

Sprague-Dawley rats were subjected to right middle cerebral artery occlusion (MCAO) for 2h using intraluminal hollow filament. The ischemic rats were randomized to receive: 1) pharmacological hypothermia by intraperitoneal (i.p.) injection of dihydrocapsaicin (DHC); 2) physical hypothermia by IACIs for 10min; or 3) the combined treatments. Extent of brain injury was determined by neurological deficit, infarct volume, and apoptotic cell death at 24h and/or 7d following reperfusion. ATP and ROS levels were measured. Expression of p-Akt, cleaved Caspase-3, pro-apoptotic (AIF, Bax) and anti-apoptotic proteins (Bcl-2, Bcl-xL) was evaluated at 24h. Finally, PI3K inhibitor was used to determine the effect of p-Akt.

RESULTS

DHC or IACIs each exhibited hypothermic effect and neuroprotection in rat MCAO models. The combination of pharmacological and physical approaches led to a faster and sustained reduction in brain temperatures and improved ischemia-induced injury than either alone (P<0.01). Furthermore, the combination treatment favorably increased the expression of anti-apoptotic proteins and decreased pro-apoptotic protein levels (P<0.01 or 0.05). This neuroprotective effect was largely blocked by p-Akt inhibition, indicating a potential role of Akt pathway in this mechanism (P<0.01 or 0.05).

CONCLUSIONS

The combination approach is able to enhance the efficiency of hypothermia and efficacy of hypothermia-induced neuroprotection following ischemic stroke. The findings here move us a step closer towards translating this long recognized TH from bench to bedside.

[BASIC PHYSIOLOGICAL MECHANISMS OF HUMAN ADAPTATION TO COLD]

The article provides an overview of the literature that focuses on the main types of human adaptation to cold and mechanisms for increasing heat production. It is shown that the studies in recent years, aimed at studying the molecular mechanisms of adaptation to cold, confirmed the results of previous physiological studies have demonstrated that the major contribution to adaptive thermogenesis during cooling made by oxidative fibers in skeletal muscle (birds, marsupials, large placental and people) and brown adipose tissue (small placenta, especially rodents). The main sources of thermoregulatory heat generation are the contractile activity (thermoregulatory shivering and muscle tone), the uncoupling of oxidative phosphorylation and decrease in thermodynamic efficiency of the ATP-powered pumps (ATPase), which are induced by noradrenaline and thyroid hormones and accompanied by an increase in the consumption of oxygen and energy substrates. During long-term adaptation to cold the number and activity of mitochondria increase to provide enhanced ATP consumption.

Continuous cold exposure induces an anti-inflammatory response in mesenteric adipose tissue associated with catecholamine production and thermogenin expression in rats

OBJECTIVE

Continuous exposure to cold leads to an activation of adaptive thermogenesis in the brown adipose tissue and induction of brown/beige cell phenotype in the white adipose tissue. Thermogenic response is associated with alternatively activated macrophages producing catecholamines, which subsequently activate the uncoupling protein 1 (UCP-1). The aim of this work was to elucidate the effect of cold exposure on catecholamine and immune responses associated with adipocyte browning in the mesenteric adipose tissue (mWAT) of rat.

METHODS

The rats were exposed to continuous cold (4 °C) for 1 or 7 days. Catecholamines production and gene expressions of inflammatory and other factors, related to adipocyte "browning", were analyzed in the homogenized mWAT samples using 2-CAT ELISA kits.

RESULTS

Cold exposure induced a sympathetic response in the mWAT, evidenced by the tyrosine hydroxylase (TH) protein level rise. Induction of non-sympathetical catecholamine production was observed 7 days after cold exposure by elevated TH and phenylethanolamine-N-methyltransferase (PNMT) expression, leading to an increased epinephrine levels. Cold exposure for 7 days stimulated the infiltration of macrophages, evaluated by F4/80 and CD68 expressions, and expression of anti-inflammatory mediators, while pro-inflammatory cytokines were inhibited. Anti- inflammatory response, accompanied by de novo catecholamine production and up-regulation of β3-adrenergic receptors, led to the stimulation of UCP-1 and PGC1α expression, suggesting a cold-induced "browning" of the mWAT, mediated by alternatively activated macrophages.

CONCLUSIONS

The present data indicate that prolonged cold exposure may induce anti-inflammatory response in mWAT associated with induction of UCP-1 expression. Although functional thermogenesis in the mWAT is most likely redundant, a highly efficient dissipation of energy by UCP1 may affect the energy homeostasis in this visceral fat.

Cold Shock Proteins Are Expressed in the Retina Following Exposure to Low Temperatures

Hypothermia has been proposed as a therapeutic intervention for some retinal conditions, including ischemic insults. Cold exposure elevates expression of cold-shock proteins (CSP), including RNA-binding motif protein 3 (RBM3) and cold inducible RNA-binding protein (CIRP), but their presence in mammalian retina is so far unknown. Here we show the effects of hypothermia on the expression of these CSPs in retina-derived cell lines and in the retina of newborn and adult rats. Two cell lines of retinal origin, R28 and mRPE, were exposed to 32°C for different time periods and CSP expression was measured by qRT-PCR and Western blotting. Neonatal and adult Sprague-Dawley rats were exposed to a cold environment (8°C) and expression of CSPs in their retinas was studied by Western blotting, multiple inmunofluorescence, and confocal microscopy. RBM3 expression was upregulated by cold in both R28 and mRPE cells in a time-dependent fashion. On the other hand, CIRP was upregulated in R28 cells but not in mRPE. In vivo, expression of CSPs was negligible in the retina of newborn and adult rats kept at room temperature (24°C). Exposure to a cold environment elicited a strong expression of both proteins, especially in retinal pigment epithelium cells, photoreceptors, bipolar, amacrine and horizontal cells, Müller cells, and ganglion cells. In conclusion, CSP expression rapidly rises in the mammalian retina following exposure to hypothermia in a cell type-specific pattern. This observation may be at the basis of the molecular mechanism by which hypothermia exerts its therapeutic effects in the retina.

Peripheral Adenosine A3 Receptor Activation Causes Regulated Hypothermia in Mice That Is Dependent on Central Histamine H1 Receptors

Adenosine can induce hypothermia, as previously demonstrated for adenosine A1 receptor (A1AR) agonists. Here we use the potent, specific A3AR agonists MRS5698, MRS5841, and MRS5980 to show that adenosine also induces hypothermia via the A3AR. The hypothermic effect of A3AR agonists is independent of A1AR activation, as the effect was fully intact in mice lacking A1AR but abolished in mice lacking A3AR. A3AR agonist-induced hypothermia was attenuated by mast cell granule depletion, demonstrating that the A3AR hypothermia is mediated, at least in part, via mast cells. Central agonist dosing had no clear hypothermic effect, whereas peripheral dosing of a non-brain-penetrant agonist caused hypothermia, suggesting that peripheral A3AR-expressing cells drive the hypothermia. Mast cells release histamine, and blocking central histamine H1 (but not H2 or H4) receptors prevented the hypothermia. The hypothermia was preceded by hypometabolism and mice with hypothermia preferred a cooler environmental temperature, demonstrating that the hypothermic state is a coordinated physiologic response with a reduced body temperature set point. Importantly, hypothermia is not required for the analgesic effects of A3AR agonists, which occur with lower agonist doses. These results support a mechanistic model for hypothermia in which A3AR agonists act on peripheral mast cells, causing histamine release, which stimulates central histamine H1 receptors to induce hypothermia. This mechanism suggests that A3AR agonists will probably not be useful for clinical induction of hypothermia.

[EFFECT OF CITOFLAVIN ON THE PARAMETERS OF LIPID PEROXIDATION IN BLOOD PLASMA OF RATS UNDER COLD STRESS CONDITIONS.]

The possibility of correcting free radical oxidation of lipid membranes by the administration of cytoflavin was experimentally studied in rats. It is established that daily cold exposure for 3 h leads to increase in the level of lipid hydroperoxides, diene conjugates, and malonic dialdehyde on the background of decrease in activity of the antioxidant system in the blood of experimental animals. The introduction of cytoflavin (100 mg/kg, i.p.) for 21 day immediately prior to cold exposure leads to reliable (p < 0.05) decrease in the blood level of lipid hydroperoxides (by 13 - 21%), diene conjugates (by 24 - 25%), and malonic dialdehyde (by 20 - 33%) in comparison to rats of the control group. Analysis of the effect of cytoflavin on activity of the antioxidant system components showed that the level of ceruloplasmin and vitamin E in the blood of animals was reliably (p < 0.05) higher by 10 - 33% than analogous indicator in rats of the control group. Thus, the application of cytoflavin under conditions of long-term influence of cold on the organism of animals leads to stabilization of the processes of lipid peroxidation on the background of increased activity of the blood antioxidant system.

[THE ENERGY FUNCTION OF RAT CARDIAC MITOCHONDRIA UNDER ARTIFICIAL HYPOBIOSIS]

We investigated the energy activity of mitochondria from rat cardiomyocytes under the artificial carbon dioxide hypobiosis, which led to physiological changes in the organism (the decrease of body temperature, the reduction of heart rate, etc.). The respiratory and phosphorylation activities in mitochondria of cardiomyocytes is reduced when using two oxidation substrates (succinate and malate), which characterize the rate of the oxygen consumption by the mitochondria. The partial uncoupling of the oxidation and phosphorylation processes when using the malate unlike succinate was established. The activity of NADH-KoQ-oxidoreductase (complex I of the respiratory chain) is inhibited, but the activities of succinate dehydrogenase and cytochrome oxidase don't change. Probably, the priority of the succinate use under the artificial hypobiosis provides the support of the mitochondria functional activity on a sufficient energy level. It is evidenced by the ATP-synthetase activity. The modifications of the structural and functional state of the inner mitochondria membrane of the cardiomyocytes are directed to the adaptation under the artificial carbon dioxide hypobiosis.

[Pinealon and Cortexin influence on behavior and neurochemical processes in 18-month aged rats within hypoxia and hypothermia]

The research of Cortexin and Pinealon within two models of stress, acute hypobaric hypoxia and mild hypothermia, within 18-month aged rats has been held. The peculiarities of peptide preparations' influence on behavior and neurochemical indeces have been identified. Cortexin shows a more pronounced effect on free radical processes and caspase 3 activity in brain than Pinealon. Both preparations forward an accumulation of adrenergic mediator within rats' brains in the model of acute hypobaric hypoxia, as well as serotonin within cerebrum cortex in the model of mild hypothermia, which may underlie their geroprotective effects.

The lonely mouse - single housing affects serotonergic signaling integrity measured by 8-OH-DPAT-induced hypothermia in male mice

Male BALB/c mice single-housed for a period of three weeks were found to respond with a more marked hypothermia to a challenge with a selective serotonergic agonist (8-OH-DPAT) than their group-housed counterparts. This effect of single housing was verified by screening a genetically heterogeneous population of male mice on a C57BL/6 background from a breeding colony. Enhanced activity of the implicated receptor (5-HT1A) leading to an amplified hypothermic effect is strongly associated with depressive states. We therefore suggest that the 8-OH-DPAT challenge can be used to demonstrate a negative emotional state brought on by e.g. long-term single housing in male laboratory mice. The study emphasizes the importance of social housing, and demonstrates that male mice deprived of social contact respond with altered serotonergic signaling activity. Male mice not only choose social contact when given the option, as has previously been shown, but will also, when it is deprived, be negatively affected by its absence. We propose that the 8-OH-DPAT challenge constitutes a simple, but powerful, tool capable of manifesting the effect of social deprivation in laboratory mice. It potentially allows not only for an unbiased, biochemical evaluation of psychological stressors, but may also allow for determining whether the effect of these can be counteracted.

A mathematical model of cellular metabolism during ischemic stroke and hypothermia

Stroke is a major cause of death and disability worldwide. Therapeutic hypothermia is a potentially useful neuroprotective treatment. A mathematical model of brain metabolism during stroke is extended here to simulate the effect of hypothermia on cell survival. Temperature decreases were set to reduce chemical reaction rates and slow diffusion through ion channels according to the Q10 rule. Heat delivery to tissues was set to depend on metabolic heat generation rate and perfusion. Two cooling methods, scalp and vascular, were simulated to approximate temperature variation in the brain during treatment. Cell death was assumed to occur at continued cell membrane depolarization. Simulations showed that hypothermia to 34.5 °C induced within 1-1.5 h of stroke onset could extend cell survival time by at least 5 h in tissue with perfusion reduced by 80% of normal. There was good agreement between simulated metabolite dynamics and those reported in rat model studies.

Pharmacological inhibition of CXCR2 chemokine receptors modulates paraquat-induced intoxication in rats

Paraquat (PQ) is an agrochemical agent commonly used worldwide, which is allied to potential risks of intoxication. This herbicide induces the formation of reactive oxygen species (ROS) that ends up compromising various organs, particularly the lungs and the brain. This study evaluated the deleterious effects of paraquat on the central nervous system (CNS) and peripherally, with special attempts to assess the putative protective effects of the selective CXCR2 receptor antagonist SB225002 on these parameters. PQ-toxicity was induced in male Wistar rats, in a total dose of 50 mg/kg, and control animals received saline solution at the same schedule of administration. Separate groups of animals were treated with the selective CXCR2 antagonist SB225002 (1 or 3 mg/kg), administered 30 min before each paraquat injection. The major changes found in paraquat-treated animals were: decreased body weight and hypothermia, nociception behavior, impairment of locomotor and gait capabilities, enhanced TNF-α and IL-1β expression in the striatum, and cell migration to the lungs and blood. Some of these parameters were reversed when the antagonist SB225002 was administered, including recovery of physiological parameters, decreased nociception, improvement of gait abnormalities, modulation of striatal TNF-α and IL-1β expression, and decrease of neutrophil migration to the lungs and blood. Taken together, our results demonstrate that damage to the central and peripheral systems elicited by paraquat can be prevented by the pharmacological inhibition of CXCR2 chemokine receptors. The experimental evidence presented herein extends the comprehension on the toxicodynamic aspects of paraquat, and opens new avenues to treat intoxication induced by this herbicide.

[Restoration of respiratory function of an organism after cold oppressions without warming]

In experiments on rats studied influence of intravenous introduction NazdTA on respiratory function of rats after the full termination of breath at deep hypothermia. It is shown that such method without warming application it is possible to lower on 1.5-2.0 degrees C a temperature threshold of approach full a cold paralysis of respiratory function of an organism. It confirms the hypothesis put forward earlier about an important role of infringement of balance of ions of calcium in cytoplasm of cells in development of a pathology of an organism at deep hypothermia. The received results can be used at resuscitation of victims accidental hypothermia.

Impact of ischemia-reperfusion on extracellular matrix processing and structure of the basement membrane of the heart

PURPOSE

Acute ischemic injury is a strong inductor of cardiac remodelling, resulting in structural changes of the extracellular matrix (ECM) and basement membrane (BM). In a large animal model of ischemia-reperfusion (I/R) we investigated the post-ischemic liberation of the collagen-IV-fragments Tumstatin (TUM; 28 kDa-fragment of collagen-IV-alpha-3), Arresten (ARR; 26 kDa-fragment of collagen-IV-alpha-1) and Endorepellin (LG3, 85 kDa-fragment of perlecan) which are biologically active in angiogenesis and vascularization in the post-ischemic myocardium.

METHODS AND RESULTS

In this blinded study, 30 pigs were randomized to 60 min of global I/R at either 4°C or 32°C or served as control. Three transmyocardial tissue samples were collected prior to ischemia and within 30 min and 150 min of reperfusion. Tissue content of TUM, ARR and LG3 was analyzed by western blotting and immunostaining. Within 150 min of mild hypothermic I/R a significantly increased tissue content of ARR (0.17±0.14 vs. 0.56±0.56; p = 0.001) and LG3 (1.13±0.34 vs. 2.51±1.71, p<0.001) was observed. In contrast, deep hypothermic I/R was not associated with a significant release of cleavage products. Cleavage of TUM remained unchanged irrespective of temperature. Increased matrix processing following mild hypothermia I/R is further supported by a >11fold elevation of creatine kinase (2075±2595 U/l vs. 23248±6551 U/l; p<0.001) in the coronary sinus plasma samples. Immunostaining demonstrated no changes for ARR and LG3 presentation irrespective of temperature. In contrast, TUM significantly decreased in the BM surrounding cardiomyocytes and capillaries after mild and deep hypothermic I/R, thus representing structural alterations of the BM in these groups.

CONCLUSION

The study demonstrates an early temperature-dependent processing of Col-IV as major component of the BM of cardiomyocytes and vascular endothelium. These observations support the protective effects of deep hypothermia during I/R. Furthermore, the results suggest an increased structural remodelling of the myocardial basement membrane with potential functional impairment during mild hypothermic I/R which may contribute to the progression to post-ischemic heart failure.

Hormonal synchronization of lipopolysaccharide-induced hypothermic response in rats

BACKGROUND

Recent experimental evidence suggests that lipopolysaccharide (LPS)-induced hypothermia is an adaptive thermoregulatory strategy against immunological challenge in rats. We hypothesized that the hormones which are predominantly responsible for energy homeostasis may have efferent signaling roles for development of the hypothermia.

AIM

The aim of the study was to evaluate the changes of hypothalamic-pituitary-thyroid (HPT) and hypothalamic- pituitary-adrenal (HPA) axis hormones, leptin and erythropoietin at various phases of LPS-induced hypothermia such as the initial phase, nadir and the end of the response in blood sampled rats.

MATERIAL AND METHODS

Body temperature of adult male albino Wistar rats was recorded by biotelemetry. E. coli O111:B4 LPS (250 μg/kg, ip) was injected alone or with SC-560, a cyclooxygenase-1 selective inhibitor (1 mg/kg, sc).

RESULTS

Serum FT4 levels elevated at the initial phase, but FT3 levels decreased at nadir and remained low at the end of the response. Meanwhile, no change was observed in TSH levels. Serum adrenocorticotropic hormone (ACTH) levels reduced at the initial phase and serum corticosterone levels decreased at nadir without any change in serum corticotropin-releasing hormone (CRH) levels throughout the hypothermia. Serum leptin levels increased only at the end of the response. No change was observed in the levels of serum erythropoietin. SC-560 treatment abolished both LPS-induced hypothermia and respective hormonal changes.

CONCLUSION

Data suggest that HPT axis hormones may contribute to development of LPS-induced hypothermia in rats. Data also support the view that leptin may have a role for the recovery of hypothermic response.

Thrombin generation and fibrin clot formation under hypothermic conditions: an in vitro evaluation of tissue factor initiated whole blood coagulation

BACKGROUND

Despite trauma-induced hypothermic coagulopathy being familiar in the clinical setting, empirical experimentation concerning this phenomenon is lacking. In this study, we investigated the effects of hypothermia on thrombin generation, clot formation, and global hemostatic functions in an in vitro environment using a whole blood model and thromboelastography, which can recapitulate hypothermia.

METHODS

Blood was collected from healthy individuals through venipuncture and treated with corn trypsin inhibitor, to block the contact pathway. Coagulation was initiated with 5pM tissue factor at temperatures 37°C, 32°C, and 27°C. Reactions were quenched over time, with soluble and insoluble components analyzed for thrombin generation, fibrinogen consumption, factor (f)XIII activation, and fibrin deposition. Global coagulation potential was evaluated through thromboelastography.

RESULTS

Data showed that thrombin generation in samples at 37°C and 32°C had comparable rates, whereas 27°C had a much lower rate (39.2 ± 1.1 and 43 ± 2.4 nM/min vs 28.6 ± 4.4 nM/min, respectively). Fibrinogen consumption and fXIII activation were highest at 37°C, followed by 32°C and 27°C. Fibrin formation as seen through clot weights also followed this trend. Thromboelastography data showed that clot formation was fastest in samples at 37°C and lowest at 27°C. Maximum clot strength was similar for each temperature. Also, percent lysis of clots was highest at 37°C followed by 32°C and then 27°C.

CONCLUSIONS

Induced hypothermic conditions directly affect the rate of thrombin generation and clot formation, whereas global clot stability remains intact.

Fuzi-Lizhong pill compensates hypothyroid-hypothermia via ghrelin release

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzi-Lizhong pill (FLZ) is a traditional Chinese medicine for treating patients with Spleen Yang deficient syndrome. Ghrelin, a peptide with 28 amino acid residues, plays multiple roles in thermogenesis. This study aims to explore FLZ regulating ghrelin to compensate hypothermia in rats with hypothyroid and indigestion.

MATERIALS AND METHODS

In litter-matched rats, hypothermia was developed with both thyroidectomy at d1 and interscapular brown adipose (IBA) removal at d42, indigestion was induced with both high fat diet and fasting-feeding cycle from d56; the littermates with hypothermia and indigestion were administrated with FLZ from d70. Adaptive thermogenesis, thyroid hormones, metabolites, ghrelin dynamics were measured at d98.

RESULTS

The results showed that plasma ghrelin levels were inversely correlated with the gastric ghrelin levels and adaptive thermogenesis in rats undergone both thyroidectomy and IBA removal. Fatty diet and FLZ enhanced the increase of plasma ghrelin of hypothyroid rats. These were supported by the changes of plasma thyroid related hormones, plasma metabolites, gastric ghrelin mRNA and protein, and the effects of fatty diet or FLZ.

CONCLUSIONS

Our results suggest that more ghrelin release compensate chronic hypothermia in rats with both hypothyroidism and indigestion. It could explain the mechanisms of FLZ in relieving chronic hypothermia.

Antidepressant-like effect of ethanol extract from Zuojin Pill, containing two herbal drugs of Rhizoma Coptidis and Fructus Evodiae, is explained by modulating the monoaminergic neurotransmitter system in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Zuojin Pill (ZJP), a traditional Chinese medicinal decoction, contains two herbal drugs: Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. in the ratio of 6:1 (w/w). Previous pharmacological studies have shown that two herbs in ZJP have the antagonistic effects on catecholamine secretion in bovine adrenal medullary cells. Furthermore, the alkaloids from the two herbs in ZJP may provide a protective effect for depression in individuals with a low expressing 5-HTT allele by increasing receptor concentration in serotonergic neurons. However, antidepressant effect has not been reported before and has not been fully clarified.

AIM OF THE STUDY

The present study aimed to investigate the antidepressant potential of ethanol extract from ZJP and its monoaminergic mechanism in mice.

MATERIALS AND METHODS

Seven alkaloids were determined from the ethanol extract of ZJP using High Performance Liquid Chromatography (HPLC) with the gradient mobile phase. The ethanol extract from ZJP was used to evaluate the antidepressant potential in mice. Mouse models of depression including the tail suspension test (TST) and the forced swim test (FST) were used to evaluate the effects of the ethanol extract from ZJP. A possible mechanism was explored in the tests of antagonism of reserpine-induced ptosis and hypothermia, and 5-HTP induced head twitch response in mice. The contents of monoamine neurotransmitters including norepinephrine (NE), serotonin (5-hydroxytryptamine or 5-HT) in hippocampus of mice and NE, 5-HT, dopamine (DA) in striatum of mice were determined by HPLC system with Electrochemical Detector (ECD).

RESULTS

The results showed that intragastric administration of the ethanol extract from ZJP (5, 10, 20mg/kg) or fluoxetine (7.5mg/kg) significantly reduced the duration of immobility in TST and FST. However, the effect was not dose-dependent. Ethanol extract from ZJP (5, 10, 20mg/kg) also increased the accumulative number of the 5-HTP-induced head twitch response in mice. The mice were treated with the ethanol extract from ZJP (5, 10, 20mg/kg) or fluoxetine (7.5mg/kg), which could antagonize reserpine-induced ptosis and hypothermia, moreover, both of them could elevate the contents of NE, 5-HT in hippocampus as well as NE, 5-HT, DA in striatum significantly.

CONCLUSION

These results indicate that the ethanol extract from ZJP produced antidepressant-like effect and the possible mechanism, at least in part, is via the central monoaminergic neurotransmitter system and 5-HT plays a major role.

Hypothermia inhibits expression of CD11b (MAC-1) and CD162 (PSGL-1) on monocytes during extracorporeal circulation

AIM

The aim of the present study was to investigate the effect of different hypothermic temperatures on the expression of cellular adhesion molecules on leukocytes.

MATERIALS AND METHODS

Circulation of blood from six volunteers was performed in an extracorporeal circulation model at 36°C, 28°C and 18°C for 30 minutes. Expression of CD11b, CD54 and CD162 on monocytes was measured using flow cytometry.

RESULTS

Expression of CD11b significantly decreased at 18°C and at 28°C compared to 36°C. A significant reduction of CD162 expression was found at 18°C compared to 28°C and 36°C and at 28°C compared to 36°C. No association was found between temperature and expression of CD54.

CONCLUSION

Expression of CD11b and CD162 on monocytes has a temperature-dependent regulation, with decreased expression during hypothermia, which may result in an inhibition of leukocyte-endothelial and leukocyte-platelet interaction. This beneficial effect may influence the extracorporeal circulation-related inflammatory response and tissue damage.

The impact of biosampling procedures on molecular data interpretation

The separation between biological and technical variation without extensive use of technical replicates is often challenging, particularly in the context of different forms of protein and peptide modifications. Biosampling procedures in the research laboratory are easier to conduct within a shorter time frame and under controlled conditions as compared with clinical sampling, with the latter often having issues of reproducibility. But is the research laboratory biosampling really less variable? Biosampling introduces within minutes rapid tissue-specific changes in the cellular microenvironment, thus inducing a range of different pathways associated with cell survival. Biosampling involves hypoxia and, depending on the circumstances, hypothermia, circumstances for which there are evolutionarily conserved defense strategies in the range of species and also are relevant for the range of biomedical conditions. It remains unclear to what extent such adaptive processes are reflected in different biosampling procedures or how important they are for the definition of sample quality. Lately, an increasing number of comparative studies on different biosampling approaches, post-mortem effects and pre-sampling biological state, have investigated such immediate early biosampling effects. Commonalities between biosampling effects and a range of ischemia/reperfusion- and hypometabolism/anoxia-associated biological phenomena indicate that even small variations in post-sampling time intervals are likely to introduce a set of nonrandom and tissue-specific effects of experimental importance (both in vivo and in vitro). This review integrates the information provided by these comparative studies and discusses how an adaptive biological perspective in biosampling procedures may be relevant for sample quality issues.

[Mechanisms of actoprotective action of succinic acid's derivatives]

Research on establishment of mechanisms of metabolitotropic compounds' actoprotective action--derivatives of succinic acid yakton and mexidol, based on the definition of their antihypoxic, antioxidant, mitoprotective, and ergogenic properties are presented in this article. In case of hypoxic, haemic, and circulatory hypoxia yakton and mexidol influence on parameters of prooxidant-antioxidant homeostasis, as well as prevent disturbances of glycolysis, content of macroergic compounds, changes of RNA-content in nerve tissue, and development of mitochondrial dysfunction. Yakton's actoprotective effect based on enhancement of adenine nucleotides' content in liver, myocardium, and skeletal muscles is also established with high-speed loading, as well as using preliminary cooling or hyperthermia. Wide range of yakton's effects (antihypoxic, membraneprotective, cardioprotective, etc.) is also confirmed according to the data of quantum-chemical research.

Antipurinergic therapy corrects the autism-like features in the poly(IC) mouse model

BACKGROUND

Autism spectrum disorders (ASDs) are caused by both genetic and environmental factors. Mitochondria act to connect genes and environment by regulating gene-encoded metabolic networks according to changes in the chemistry of the cell and its environment. Mitochondrial ATP and other metabolites are mitokines-signaling molecules made in mitochondria-that undergo regulated release from cells to communicate cellular health and danger to neighboring cells via purinergic signaling. The role of purinergic signaling has not yet been explored in autism spectrum disorders.

OBJECTIVES AND METHODS

We used the maternal immune activation (MIA) mouse model of gestational poly(IC) exposure and treatment with the non-selective purinergic antagonist suramin to test the role of purinergic signaling in C57BL/6J mice.

RESULTS

We found that antipurinergic therapy (APT) corrected 16 multisystem abnormalities that defined the ASD-like phenotype in this model. These included correction of the core social deficits and sensorimotor coordination abnormalities, prevention of cerebellar Purkinje cell loss, correction of the ultrastructural synaptic dysmorphology, and correction of the hypothermia, metabolic, mitochondrial, P2Y2 and P2X7 purinergic receptor expression, and ERK1/2 and CAMKII signal transduction abnormalities.

CONCLUSIONS

Hyperpurinergia is a fundamental and treatable feature of the multisystem abnormalities in the poly(IC) mouse model of autism spectrum disorders. Antipurinergic therapy provides a new tool for refining current concepts of pathogenesis in autism and related spectrum disorders, and represents a fresh path forward for new drug development.

[Effect of mild hypothermia on the expression of acid-sensing ion channels 1a and 2a following global cerebral ischemia-reperfusion in rats]

OBJECTIVE

To investigate the effects of mild hypothermia on the expression of ASIC1a and ASIC2a in the rat hippocampus following global cerebral ischemia-reperfusion, so as to speculate the underlying mechanisms of neuroresuscitation.

METHODS

Ninety five male SD rats were randomly divided into five groups (n = 19): sham operation group (I), model group (II), mild hypothermia group (III), PcTX1 group (IV), mild hypothermia combined PcTX1 group (V). Transient (15 min) global cerebral ischemia was induced by the four-vessel occlusion. PcTX1 (500 ng/ml) 6 µl were injected into lateral cerebral ventricle immediately after reperfusion in group IV and V, while the equal volume of normal saline was injected into lateral cerebral ventricle immediately after reperfusion in the other three groups. At the same time, mild hypothermia after reperfusion was performed and lasted for 6 hours in group III and V, the rectal temperature was reduced to 32 - 33°C within 15 min, while it was maintained at 36 - 37°C by lamp in other three groups. Determination the expression of ASIC1a and ASIC2a protein at 6 h and 24 h of reperfusion, and the expression of ASIC1a and ASIC2a mRNA at 24 h of reperfusion. Observe the pathomorphological changes of hippocampal CA1 neurons at 24 h of reperfusion. Detect the brain water content at 72 h of reperfusion.

RESULTS

The difference in the expression of ASIC1a mRNA and protein among the groups was not changed significantly (P > 0.05). Compared with group I, the expression of ASIC2a mRNA and ASIC2a protein was up-regulated in other groups (P < 0.05). It was significantly higher in group III and V than in group II and IV (P < 0.05). Compared to 6 h of reperfusion, the expression of ASIC2a protein was higher in group II, III, IV and V respectively after 24 h of reperfusion. Compared to group I, the number of pyramidal cells in CA1 region of hippocampus in group II, III, IV and V were decreased at 24 h of reperfusion (P < 0.01). Compared to group II, the number of pyramidal cells in CA1 region of hippocampus in group III, IV and V were increased at 24 h of reperfusion (P < 0.01); and compared to group III and IV, the number of pyramidal cells at 24 h of reperfusion in group V was significantly higher (P < 0.01). Compared to group I, the content of brain water in II, III and IV group were increased at 72 h of reperfusion (P < 0.01). Compared to group II, the content of brain water in group III, IV and V were decreased at 72 h of reperfusion (P < 0.01). Giving mild hypothermia or PcTX1 could alleviate the damage in CA1 region of hippocampus, with the best effect in group V, which administers PcTX1 combined mild hypothermia.

CONCLUSION

Mild hypothermia attenuates global cerebral ischemia-reperfusion of rat, which may up-regulate the expression of ASIC2a mRNA and protein. Mild hypothermia combined by PcTX1 could induce neuroresuscitation.

β(1) Adrenergic receptor is key to cold- and diet-induced thermogenesis in mice

Brown adipose tissue (BAT) is predominantly regulated by the sympathetic nervous system (SNS) and the adrenergic receptor signaling pathway. Knowing that a mouse with triple β-receptor knockout (KO) is cold intolerant and obese, we evaluated the independent role played by the β(1) isoform in energy homeostasis. First, the 30  min i.v. infusion of norepinephrine (NE) or the β(1) selective agonist dobutamine (DB) resulted in similar interscapular BAT (iBAT) thermal response in WT mice. Secondly, mice with targeted disruption of the β(1) gene (KO of β(1) adrenergic receptor (β(1)KO)) developed hypothermia during cold exposure and exhibited decreased iBAT thermal response to NE or DB infusion. Thirdly, when placed on a high-fat diet (HFD; 40% fat) for 5 weeks, β(1)KO mice were more susceptible to obesity than WT controls and failed to develop diet-induced thermogenesis as assessed by BAT Ucp1 mRNA levels and oxygen consumption. Furthermore, β(1)KO mice exhibited fasting hyperglycemia and more intense glucose intolerance, hypercholesterolemia, and hypertriglyceridemia when placed on the HFD, developing marked non-alcoholic steatohepatitis. In conclusion, the β(1) signaling pathway mediates most of the SNS stimulation of adaptive thermogenesis.