Histamine and astrocyte function.

Astrocytes support the brain through numerous functional interactions in health and disease. The recent advances in our knowledge of astrocyte involvement in various neurological disorders raised up several questions about their role and functioning in the central nervous system. From the evidence discussed in this review, we show that histamine importantly influences the main astrocytic activities such as ion homeostasis, energy metabolism, neurotransmitter clearance, neurotrophic activity and immune response. These processes are mediated through at least three histamine receptor subtypes, H1, H2 and H3, expressed on the astrocyte surface. Thus, we recognize histamine as an important player in the modulation of astrocytic functions that deserves further considerations in exploring involvement of astrocytes in neurological disorders.

Chronic pain treatment: the influence of tricyclic antidepressants on serotonin release and uptake in mast cells.

The involvement of serotonin (5-HT) in chronic pain mechanisms is established. 5-HT inhibits central painful stimuli, but recent data suggests that 5-HT could also enhance pain stimulus from the periphery, where mast cells play an important role. We aimed in our study to clarify the influence of selected tricyclic antidepressants (TCAs) on mast cell function: secretion, uptake, and reuptake of 5-HT, that could interfere with 5-HT levels and in this way contribute to the generation of pain. As an experimental model, we used isolated rat peritoneal mast cells and incubated them with selected TCAs (clomipramine, amitriptyline, doxepin, and imipramine) under different experimental conditions. 5-HT release, uptake, and reuptake were determined spectrofluorometrically. We showed that TCAs were able to inhibit 5-HT secretion from mast cells, as well as uptake of exogenous 5-HT and reuptake of secreted 5-HT back into mast cells. The effects of TCAs were concentration dependent; higher concentrations of TCAs inhibited the secretion of 5-HT induced by compound 48/80, whereas lower concentrations of TCAs inhibited 5-HT uptake. The most effective TCA was halogenated clomipramine. As TCAs are well introduced in chronic pain treatment, the insight into mechanisms of action is important for an understanding of their effect in various pain conditions.

Staurosporine induces apoptosis and necroptosis in cultured rat astrocytes.

Apoptosis and necroptosis are highly regulated, interconnected forms of a cell death. The distinction between them is critical, because necroptosis may cause significant cell loss and local inflammation, whereas apoptosis is essential for tissue homeostasis. The same stimulus can induce both apoptosis and necroptosis. Both forms of a cell death were detected in various pathologies, including pathologies in the central nervous system. Astrocytes are a large, heterogeneous cell population in the central nervous system, with many supportive, developmental functions. Although their demise may seriously impair normal functions of the central nervous system, it is still poorly understood. In this study, apoptosis and necroptosis were induced in cultured rat astrocytes by staurosporine. When a low concentration (10(-7) M) of staurosporine was applied, a significantly increased proportion of early apoptotic cells was detected after regeneration in a staurosporine free medium. The proportion of necroptotic cells was already increased without regeneration after 3 hours of exposure to staurosporine. When a higher (10(-6) M) concentration of staurosporine was applied, further significantly increased necroptosis was detected after regeneration in a staurosporine free medium. Necroptosis was significantly reduced when RIP1 kinase was inhibited by necrostatin-1, whereas inhibition of caspases with z-vad-fmk, an irreversible pan-caspase inhibitor, did not prevent necroptosis. This report of necroptosis induced by staurosporine represents a simple approach for the in vitro induction and detection of apoptosis and necroptosis.

Staurosporine induces different cell death forms in cultured rat astrocytes.

BACKGROUND: Astroglial cells are frequently involved in malignant transformation. Besides apoptosis, necroptosis, a different form of regulated cell death, seems to be related with glioblastoma genesis, proliferation, angiogenesis and invasion. In the present work we elucidated mechanisms of necroptosis in cultured astrocytes, and compared them with apoptosis, caused by staurosporine. MATERIALS AND METHODS: Cultured rat cortical astrocytes were used for a cell death studies. Cell death was induced by different concentrations of staurosporine, and modified by inhibitors of apoptosis (z-vad-fmk) and necroptosis (nec-1). Different forms of a cell death were detected using flow cytometry. RESULTS: We showed that staurosporine, depending on concentration, induces both, apoptosis as well as necroptosis. Treatment with 10(-7) M staurosporine increased apoptosis of astrocytes after the regeneration in a staurosporine free medium. When caspases were inhibited, apoptosis was attenuated, while necroptosis was slightly increased. Treatment with 10(-6) M staurosporine induced necroptosis that occurred after the regeneration of astrocytes in a staurosporine free medium, as well as without regeneration period. Necroptosis was significantly attenuated by nec-1 which inhibits RIP1 kinase. On the other hand, the inhibition of caspases had no effect on necroptosis. Furthermore, staurosporine activated RIP1 kinase increased the production of reactive oxygen species, while an antioxidant BHA significantly attenuated necroptosis. CONCLUSION: Staurosporine can induce apoptosis and/or necroptosis in cultured astrocytes via different signalling pathways. Distinction between different forms of cell death is crucial in the studies of therapy-induced necroptosis.

Cytotoxic Effects of Cannabidiol on Neonatal Rat Cortical Neurons and Astrocytes: Potential Danger to Brain Development.

The influence of cannabidiol (CBD) on brain development is inadequately understood. Since CBD is considered a non-intoxicating drug, it has attracted great interest concerning its potential medical applicability, including in pregnant women and children. Here, we elucidated the response of perinatal rat cortical neurons and astrocytes to CBD at submicromolar (0.1, 0.5, 1, 5 µM) concentrations attainable in humans. The effect of CBD was concentration- and time-dependent and cell-specific. In neurons, 0.1 µM CBD induced an early and transient change in mitochondrial membrane potential (ΔΨm), ATP depletion, and caspase-8 activation, followed by rapid ATP recovery and progressive activation of caspase-9 and caspase-3/7, resulting in early apoptotic cell death with reduction and shortening of dendrites, cell shrinkage, and chromatin condensation. The decrease in neuronal viability, ATP depletion, and caspase activation due to CBD exposure was prevented by transient receptor potential vanilloid 1 (TRPV1) antagonist. In astrocytes, 0.5 µM CBD caused an immediate short-term dysregulation of ΔΨm, followed by ATP depletion with transient activation of caspase-8 and progressive activation of caspase-9 and caspase-3/7, leading to early apoptosis and subsequent necroptosis. In astrocytes, both TRPV1 and cannabinoid receptor 1 (CB1) antagonists protected viability and prevented apoptosis. Given that CBD is a non-intoxicating drug, our results clearly show that this is not the case during critical periods of brain development when it can significantly interfere with the endogenous cannabinoid system.

A regulatory take on cannabis and cannabinoids for medicinal use in the European Union.

The discovery of the endocannabinoid system has raised public interest in the medicinal use of cannabis, phytocannabinoids, and synthetic cannabinoids, which has always been closely regulated due to their psychotropic effects and potential abuse. The review takes a quick look at the current legal framework in the European Union, which regulates cannabis use and cultivation for medicinal purposes in line with the United Nations Conventions on the production, trade, and use of cannabis, phytocannabinoids, and synthetic cannabinoids. And while the EU legislation precisely defines requirements and marketing authorisation procedures for medicinal products for all EU member states, there is no common regulatory framework for magistral and officinal preparations containing cannabinoids, as they are exempt from marketing authorisation. Instead, their regulation is left to each member state, and it is quite uneven at this point, mainly due to cultural and historical differences between the countries, leading to different access to non-authorised medicinal products. Therefore, to meet great public interest, harmonised approaches on cannabinoid-containing products without marketing authorisation would be welcome to level the playing field in the EU.

NADPH oxidase inhibitor VAS2870 prevents staurosporine-induced cell death in rat astrocytes.

Background Astrocytes maintain central nerve system homeostasis and are relatively resistant to cell death. Dysfunction of cell death mechanisms may underlie glioblastoma genesis and resistance to cancer therapy; therefore more detailed understanding of astrocytic death modalities is needed in order to design effective therapy. The purpose of this study was to determine the effect of VAS2870, a pan-NADPH oxidase inhibitor, on staurosporine-induced cell death in astrocytes. Materials and methods Cultured rat astrocytes were treated with staurosporine as activator of cell death. Cell viability, production of reactive oxygen species (ROS), and mitochondrial potential were examined using flow cytometric analysis, while chemiluminescence analysis was performed to assess caspase 3/7 activity and cellular ATP. Results We show here for the first time, that VAS2870 is able to prevent staurosporine-induced cell death. Staurosporine exerts its toxic effect through increased generation of ROS, while VAS2870 reduces the level of ROS. Further, VAS2870 partially restores mitochondrial inner membrane potential and level of ATP in staurosporine treated cells. Conclusions Staurosporine induces cell death in cultured rat astrocytes through oxidative stress. Generation of ROS, mitochondrial membrane potential and energy level are sensitive to VAS2870, which suggests NADPH oxidases as an important effector of cell death. Consequently, NADPH oxidases activation pathway could be an important target to modulate astrocytic death.

Multiple role of histamine H1-receptor-PKC-MAPK signalling pathway in histamine-stimulated nerve growth factor synthesis and secretion.

Histamine is a potent stimulator of nerve growth factor (NGF) production in the central nerve system and in the periphery as well. In this review, the biochemical mechanisms of histamine-stimulated NGF synthesis and secretion, and interactions between histamine, interleukin-1beta, and interleukin-6 are discussed. The main signalling pathway, involved in the stimulation of NGF production by histamine, includes activation of histamine H(1)-receptor, stimulation of Ca(2+)-dependent protein kinase C and mitogen-activated protein kinase. The same signalling pathway is involved in the interactions between histamine, interleukin-1beta, and interleukin-6, where NGF secretion is amplified. Whereas histamine and interleukin-1beta cause additive stimulatory effect on NGF secretion, interaction between histamine and interleukin-6 causes a long-term synergism. Thus, activation of histamine H(1)-receptor-protein kinase C-mitogen-activated protein kinase signalling pathway plays a crucial role not only in the direct stimulation of NGF secretion by histamine, but also in the indirect stimulation via different types of interactions between histamine, interleukin-1beta, and interleukin-6, which may have important therapeutic implications in modulation of NGF production.

Cell-based therapies for cardiac repair: a meeting report on scientific observations and European regulatory viewpoints.

In the past decade, novel cell-based products have been studied in patients with acute and chronic cardiac disease to assess whether these therapies are efficacious in improving heart function and preventing the development of end-stage heart failure. Cardiac indications studied include acute myocardial infarction (AMI), refractory angina, and chronic heart failure (CHF). Increased clinical activity, experience, and multiple challenges faced by developers have been recognized at the regulatory level. In May 2014, the Committee for Advanced Therapies (CAT) discussed in an expert meeting various cell-based medicinal products developed for cardiac repair, with a focus on non-manipulated bone marrow cells, sorted bone marrow or apheresis, and expanded cells, applied to patients with AMI or CHF. The intention was to share information, both scientific and regulatory, and to examine the challenges and opportunities in this field. These aspects were considered from the quality, and non-clinical and clinical perspectives, including current imaging techniques, with a focus on AMI and CHF. The scope of this overview is to present the European regulatory viewpoint on cell-based therapies for cardiac repair in the context of scientific observations.

Manufacturing, characterization and control of cell-based medicinal products: challenging paradigms toward commercial use.

During the past decade, a large number of cell-based medicinal products have been tested in clinical trials for the treatment of various diseases and tissue defects. However, licensed products and those approaching marketing authorization are still few. One major area of challenge is the manufacturing and quality development of these complex products, for which significant manipulation of cells might be required. While the paradigms of quality, safety and efficacy must apply also to these innovative products, their demonstration may be demanding. Demonstration of comparability between production processes and batches may be difficult for cell-based medicinal products. Thus, the development should be built around a well-controlled manufacturing process and a qualified product to guarantee reproducible data from nonclinical and clinical studies.

The effects of histamine and interleukin-6 on NGF release from cortical astrocytes in primary culture.

The influence of neurotransmitter histamine and cytokine interleukin-6 (IL-6) on nerve growth factor (NGF) release was studied in rat neonatal cortical astrocytes in primary culture. Exposure of astrocytes to either histamine or IL-6 resulted in the stimulation of NGF release. Maximal stimulation of NGF release was obtained using histamine at concentration 100 nM after 24 h of treatment (2.3 fold increase over the basal secretion from the control cells). IL-6 (30 ng/ml) induced NGF secretion was 1.66 fold over the basal level. Time course of NGF release, after histamine or IL-6 treatment, showed elevation of NGF level in the culture medium after 8 h or 24 h, respectively. IL-6 antibody effectively blocked the IL-6 stimulatory effect on NGF release, but did not influence NGF release, evoked by histamine. IL-6 antibody alone did not show any influence on NGF release. Our results suggest that IL-6 and histamine stimulate release of NGF by two different and independent molecular pathways.

Molecular properties of central and peripheral histamine H1 and H2 receptors.

We identified and characterised histamine H1 and H2 receptor subtypes on rat cortical astrocytes in primary culture with radioligand binding studies and compared their molecular properties with peripheral (bovine vascular smooth muscle and endothelial cells) histamine H1 and H2 receptors. Our results showed the existence of a homogenous population of high affinity binding sites for 3H-mepyramine (Bmax = 281 fmol/mg protein, KD= 3.5 +/- 0.7 nM) and 3H-tiotidine (Bmax = 59 fmol/mg protein, KD = 1.9 +/- 0.7 nM) on astrocytes, which was further confirmed by competition binding studies using various H1 and H2 specific agonists/antagonists. We showed differences in the density of receptors and differences in the affinities of competing drugs for the same histamine receptor subtype (H1 and H2) between the tissues used, which indicate different molecular properties of the central and peripheral histamine receptors.

Ethanol and acetaldehyde disturb TNF-alpha and IL-6 production in cultured astrocytes.

Ethanol disturbs astroglial growth and differentiation and causes functional alterations. Furthermore, many signalling molecules produced by astrocytes contribute to these processes. The aim of the present study was to investigate the influence of ethanol and its primary metabolite, acetaldehyde, on TNF-alpha and IL-6 production in a rat cortical astrocyte primary culture. We are the first to report that both ethanol and acetaldehyde can modulate TNF-alpha and IL-6 secretion from cultured astrocytes. Long-term exposure (7 days) to ethanol and acetaldehyde was more toxic than an acute (24 hours) exposure. However, both compounds showed a biphasic, hormestic effect on the IL-6 secretion after the acute as well as the long-term exposure, and the maximum stimulation was reached for 50-mM ethanol and 1-mM acetaldehyde after 7-day exposure. In contrast, both compounds reduced the TNF-alpha secretion, where the effect was concentration-dependent. The catalase inhibitor 2-amino-1,2,4 triazole significantly reduced the ethanol toxicity in the cultured astrocytes after the acute as well as the long-term exposure. In conclusion, both ethanol and acetaldehyde affect the production of IL-6 and TNF-alpha in cultured astrocytes. The effect depends on the concentration of the compounds and the duration of the exposure. Acetaldehyde is a more potent toxin than ethanol, and ethanol's toxicity in the brain is at least partially due to its primary metabolite, acetaldehyde.

Hospitalizations due to poisonings in Slovenia--epidemiological aspects.

INTRODUCTION: Poisonings continue to be an important public health problem. Here we review the incidence and trend of poisoning by medicaments, drugs and biological substances in Slovenia during a five-year period, 2001-2005. We also investigate the etiological and demographic characteristics of poisoning cases in the Slovenian population, based on acute-poisoning admissions to hospitals in Slovenia. PATIENTS, MATERIALS AND METHODS: This retrospective study comprised all cases of poisoning admitted to Slovenian hospitals during a five-year period. Data were obtained from the Annual Health Statistics and from the Institute of Public Health of the Republic of Slovenia. RESULTS: Poisonings by medicaments, drugs and biological substances were found to represent more than half (61%) of the poisonings treated in hospitals. Female poisonings were recorded at a higher rate than male poisonings. The majority of cases occurred in the age group 15-49 years but age groups 1-3 years and >65 years were also shown to be at risk. Children under 3 years of age were poisoned by accident, whereas most cases in teenagers and adults were intentional poisonings (attempted suicide); in the oldest age group, rates of intentional and unintentional poisonings were similar. Although there was a significant downward trend in the overall number of cases from 2001 to 2005, the incidence in children aged 1-3 years and in persons >65 years remained the same. CONCLUSIONS: Poisoning is an important health problem. A multidisciplinary approach is required so that preventive measures may be increased for all groups at risk.

Comparison of ethanol and acetaldehyde toxicity in rat astrocytes in primary culture.

This study compared the effects of toxicity of ethanol and its first metabolite acetaldehyde in rat astrocytes through cell viability and cell proliferation. The cells were treated with different concentrations of ethanol in the presence or absence of a catalase inhibitor 2-amino-1,2,4 triazole (AMT) or with different concentrations of acetaldehyde. Cell viability was assessed using the trypan blue test. Cell proliferation was assessed after 24 hours and after seven days of exposure to either ethanol or acetaldehyde.We showed that both ethanol and acetaldehyde decreased cell viability in a dose-dependent manner. In proliferation studies, after seven days of exposure to either ethanol or acetaldehyde, we observed a significant dose-dependent decrease in cell number. The protein content study showed biphasic dose-response curves, after 24 hours and seven days of exposure to either ethanol or acetaldehyde. Co-incubation in the presence of AMT significantly reduced the inhibitory effect of ethanol on cell proliferation.We concluded that long-term exposure of astrocytes to ethanol is more toxic than acute exposure. Acetaldehyde is a much more potent toxin than ethanol, and at least a part of ethanol toxicity is due to ethanol's first metabolite acetaldehyde.