Ketamine - A New Antidepressant Drug with Anti-Inflammatory Properties.

Ketamine is a new, potent and rapid-acting antidepressant approved for therapy of treatment-resistant depression, which has a different mechanism of action than currently-available antidepressant therapies. It owes its uniquely potent antidepressant properties to a complex mechanism of action, which currently remains unclear. However, it is thought that it acts by modulating the functioning of the glutamatergic system, which plays an important role in the process of neuroplasticity associated with depression. However, preclinical and clinical studies have also found ketamine to reduce inflammation, either directly or indirectly (by activating neuroprotective branches of the kynurenine pathway), among patients exhibiting higher levels of inflammation. Inflammation and immune system activation are believed to play key roles in the development and course of depression. Therefore, the present work examines the role of the antidepressant effect of ketamine and its anti-inflammatory properties in the treatment of depression. SIGNIFICANCE STATEMENT: The present work examines the relationship between the antidepressant effect of ketamine and its anti-inflammatory properties, and the resulting benefits in treatment-resistant depression (TRD). The antidepressant mechanism of ketamine remains unclear, and there is an urgent need to develop new therapeutic strategies for treatment of depression, particularly TRD.

Antidepressant mechanisms of ketamine's action: NF-κB in the spotlight.

Ketamine recently approved for therapy of treatment-resistant depression shows a complex and not fully understood mechanism of action. Apart from its classical glutamatergic N-methyl-D-aspartate receptor antagonistic action, it is thought that anti-inflammatory properties of the drug are of clinical relevance due to the contribution of activated inflammatory mediators to the pathophysiology of depression and non-responsiveness of a group of patients to current antidepressant therapies. In a search of the mechanism underlying anti-inflammatory effects of ketamine, the nuclear factor kappa B transcription factor (NF-κB) has been proposed as a target for ketamine. The NF-κB forms precisely regulated protein signaling cascades enabling a rapid response to cellular stimuli. In the central nervous systems, NF-κB signaling appears to have pleiotropic but double-edged functions: on the one hand it participates in the regulation of processes that are crucial in the treatment of depression, such as neuroplasticity, neurogenesis or neuronal survival, on the other - in the activation of neuroinflammation and cell death. Ketamine has been found to reduce inflammation mediated by NF-κB, leading to decreased level of pro-inflammatory cytokines and other inflammatory or stress mediators. Therefore, this review presents recent data on the significance of the NF-κB cascade in the mechanism of ketamine's action and its future perspectives in designing new strategies for the treatment of depression.

Dual Targeting Ligands-Histamine H3 Receptor Ligands with Monoamine Oxidase B Inhibitory Activity-In Vitro and In Vivo Evaluation.

The clinical symptoms of Parkinson's disease (PD) appear when dopamine (DA) concentrations in the striatum drops to around 20%. Simultaneous inhibitory effects on histamine H3 receptor (H3R) and MAO B can increase DA levels in the brain. A series of compounds was designed and tested in vitro for human H3R (hH3R) affinity and inhibitory activity to human MAO B (hMAO B). Results showed different activity of the compounds towards the two biological targets. Most compounds had poor affinity for hH3R (Ki > 500 nM), but very good inhibitory potency for hMAO B (IC50 < 50 nM). After further in vitro testing (modality of MAO B inhibition, permeability in PAMPA assay, cytotoxicity on human astrocyte cell lines), the most promising dual-acting ligand, 1-(3-(4-(tert-butyl)phenoxy)propyl)-2-methylpyrrolidine (13: hH3R: Ki = 25 nM; hMAO B IC50 = 4 nM) was selected for in vivo evaluation. Studies in rats of compound 13, in a dose of 3 mg/kg of body mass, confirmed its antagonistic effects for H3R (decline in food and a water consumption), decline in MAO B activity (>90%) in rat cerebral cortex (CTX), and an increase in DA content in CTX and striatum. Moreover, compound 13 caused a slight increase in noradrenaline, but a reduction in serotonin concentration in CTX. Thus, compound 13 is a promising dual-active ligand for the potential treatment of PD although further studies are needed to confirm this.

Diclofenac Diminished the Unfolded Protein Response (UPR) Induced by Tunicamycin in Human Endothelial Cells.

Diclofenac belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs), which are amongst the most frequently prescribed drugs to treat fever, pain and inflammation. Despite the presence of NSAIDs on the pharmaceutical market for several decades, epidemiological studies have shown new clinical applications of NSAIDs, and new mechanisms of their action were discovered. The unfolded protein response (UPR) activated under endoplasmic reticulum (ER) stress is involved in the pathophysiology of many diseases and may become a drug target, therefore, the study evaluated the effects of diclofenac on the tunicamycin-induced UPR pathways in endothelial cells. RT PCR analysis showed that diclofenac significantly inhibited activation of ER stress-responsive genes, i.e., CHOP/DITT3, GRP78/HSPA5 and DNAJB9. Additionally, the drug diminished the significant upregulation and release of the GRP78 protein, as evaluated using the ELISA assay, which was likely to be involved in the mechanism of the UPR activation resulting in apoptosis induction in endothelial cells. These results suggest the value of diclofenac as a factor capable of restoring the ER homeostasis in endothelial cells by diminishing the UPR.

The Importance of Endoplasmic Reticulum Stress as a Novel Antidepressant Drug Target and Its Potential Impact on CNS Disorders.

Many central nervous system (CNS) diseases, including major depressive disorder (MDD), are underpinned by the unfolded protein response (UPR) activated under endoplasmic reticulum (ER) stress. New, more efficient, therapeutic options for MDD are needed to avoid adverse effects and drug resistance. Therefore, the aim of the work was to determine whether UPR signalling pathway activation in astrocytes may serve as a novel target for antidepressant drugs. Among the tested antidepressants (escitalopram, amitriptyline, S-ketamine and R-ketamine), only S-ketamine, and to a lesser extent R-ketamine, induced the expression of most ER stress-responsive genes in astrocytes. Furthermore, cell viability and apoptosis measuring assays showed that (R-)S-ketamine did not affect cell survival under ER stress. Under normal conditions, S-ketamine played the key role in increasing the release of brain-derived neurotrophic factor (BDNF), indicating that the drug has a complex mechanism of action in astrocytes, which may contribute to its therapeutic effects. Our findings are the first to shed light on the relationship between old astrocyte specifically induced substance (OASIS) stabilized by ER stress and (R-)S-ketamine; however, the possible involvement of OASIS in the mechanism of therapeutic ketamine action requires further study.

Involvement of vascular endothelial growth factor (VEGF) and mitogen-activated protein kinases (MAPK) in the mechanism of neuroleptic drugs.

BACKGROUND: Recent evidence suggests that the mitogen activated protein kinase (MAPK)-associated signaling pathway in the frontal cortical areas demonstrates abnormal activity in cases of schizophrenia. Moreover, schizophrenia patients often display alterations in the regional cellular energy metabolism and blood flow of the brain; these are shown to parallel changes in angiogenesis primarily mediated by vascular endothelial growth factor (VEGF). METHODS: The present study examines the differential effects of time-dependent treatment with haloperidol, olanzapine and amisulpride (20µM) on VEGF and MAPK mRNA expression and VEGF level, using the T98 cell line as an example of nerve cells. For the purposes of comparison, the effect of neuroprotective pituitary adenylate cyclase-activating polypeptide (PACAP) on the expression of VEGF mRNA and secretion were also evaluated in this cell model. RESULTS: RT-PCR analysis revealed that all the tested neuroleptics increased VEGF mRNA expression after 72-h incubation; however, only haloperidol and olanzapine also increased the level of VEGF detected by ELISA, and they demonstrated significantly stronger effects than PACAP. Haloperidol and olanzapine, but not amisulpride, decreased MAPK14 mRNA expression in T98G cells after 72-h incubation. CONCLUSION: The obtained results suggest that haloperidol and olanzapine can trigger the MAPK and VEGF signaling pathway, which may contribute to their neuroprotective mechanism of action.

The differential effects of neuroleptic drugs and PACAP on the expression of BDNF mRNA and protein in a human glioblastoma cell line.

Despite numerous studies, the molecular mechanisms underpinning the action of antipsychotic drugs remain not fully understood. It has been suggested that, in addition to the modulation of monoaminergic neurotransmission, antipsychotic drugs can also affect the expression of neurotrophic factors in the brain. The present study examines the effects of a first-generation neuroleptic drug (FGA; haloperidol) and two second-generation neuroleptic drugs (SGAs; olanzapine and amisulpride) on the expression and levels of brain-derived neurotrophic factor (BDNF) in an astrocyte-like T98G glioblastoma cell line. The effects of these drugs were compared to the action of PACAP38, a neuropeptide with well-known BDNF-mediated neuroprotective effects. The tested neuroleptics differentially regulated the mRNA expression and protein level of BDNF depending on concentration and incubation time. Real-time PCR analysis demonstrates that, of the three tested neuroleptics, both haloperidol and olanzapine at a concentration of 5 µM (but not at 20 µM) increased BDNF mRNA expression with similar efficacy after 72-hour incubation. In order to confirm the observed changes in the mRNA expression of BDNF, a protein expression assay was performed. The exposure of cells to 5 µM olanzapine alone for 72 hours increased BDNF concentration in the culture medium by 29%. Additionally, PACAP significantly up-regulated BDNF mRNA expression in T98G cells and the obtained results correlated positively with the increased production of BDNF protein, 22% above control values. Our findings show that olanzapine, similarly to exogenous PACAP38, increased BDNF mRNA expression and protein release, which can contribute to its neuroprotective mechanism of action in the cells of non-neuronal origin. The results of the paper show that olanzapine, similarly to exogenous PACAP38, increased BDNF mRNA expression and protein release, which can contribute to its neuroprotective mechanism of action in the cells of nonneuronal origin. The results of the present paper confirm the findings that BDNF may represent the key target for olanzapine and PACAP.

Neuroleptic Drugs and PACAP Differentially Affect the mRNA Expression of Genes Encoding PAC1/VPAC Type Receptors.

Several lines of evidence suggest that pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide playing an important role as a neuromodulator. It has been indicated that PACAP is associated with mental diseases, and that regulation of the PACAPergic signals could be a potential target for the treatment of such psychiatric states as schizophrenia. Recent studies have suggested that action of neuroleptic drugs is mediated not only by dopaminergic and serotonergic neurotransmission, but also via neuropeptides which may act both as neurotransmitters and as neuromodulators. The present study examines whether currently-used neuroleptics influence the action of PACAP receptors, whose expression is altered in a schizophrenic patient. Real-time polymerase chain reaction (PCR) was used to examine the effects of haloperidol, olanzapine and amisulpride on the expression of genes coding PAC1/VPAC type receptors in the T98G glioblastoma cell line, as an example of an in vitro model of glial cells. PAC1 mRNA expression fell after 24-h incubation with haloperidol or olanzapine; however the effect was not maintained after 72 h, and haloperidol even up-regulated PAC1 mRNA expression in a dose-dependent manner. All the examined drugs decreased VPAC2 mRNA expression, especially after 72-h incubation. Haloperidol (typical neuroleptic) was distinctly more potent than atypical neuroleptic drugs (olanzapine and amisulpride). In addition, PACAP increased PAC1 and VPAC2 mRNA expression. In conclusion, our findings suggest PACAP receptors may be involved in the mechanism of typical and atypical neuroleptic drugs.

The cyclic AMP effects and neuroprotective activities of PACAP and VIP in cultured astrocytes and neurons exposed to oxygen-glucose deprivation.

BACKGROUND: Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are endogenous peptides, widely expressed in the central and peripheral nervous system. The adenylyl cyclase (AC)/cyclic AMP (cAMP) is their main intracellular signal transduction pathway. Numerous data suggest that PACAP and VIP have considerable neuroprotective potential, indicating the possibility for their use as new therapeutic strategies in stroke treatment. The aim of this study was to evaluate the effect of oxygen-glucose deprivation (OGD) - an established in vitro model for ischemic cell stress - on PACAP and VIP-evoked receptor-mediated cAMP generation in glial and neuronal cells, and to determine whether PACAP and VIP have neuroprotective activity under these conditions. METHODS: The formation of [(3)H]cAMP by PACAP, VIP and forskolin (a direct activator of AC) was measured in [(3)H]adenine prelabeled primary rat glial and neuronal cells under normoxia and OGD conditions. The effects of PACAP and VIP on cell viability were measured using the MTT conversion method, and were compared to tacrolimus (FK506), a well known neuroprotective agent. RESULTS: The OGD model inhibited the PACAP and VIP-induced cAMP formation in rat astrocytes and neurons. Incubation of neuronal cells with PACAP prevented OGD-induced cell death, more efficiently than VIP and FK506. CONCLUSION: The obtained results showed that hypoxia/ischemia may trigger down-regulation of the brain AC-coupled PACAP/VIP receptors, with a consequent decrease of PACAP- and/or VIP-ergic-dependent cAMP-driven signaling. Moreover, our findings indicate that PACAP and VIP can prevent the deleterious effect of OGD on rat neuronal cells.

The biological activities of cinnamon, geranium and lavender essential oils.

Acinetobacter sp. represent an important cause of nosocomial infections. Their resistance to some antibiotics, their ability to survive on inanimate surfaces in the hospital environment and their ability to produce biofilms contributes to their virulence. The aim of the study was to determine the antibacterial properties of cinnamon, lavender and geranium essential oils against bacteria of the genus Acinetobacter isolated from several clinical materials and from the hospital environment. A comprehensive evaluation of the susceptibility of Acinetobacter sp. clinical strains to recommended antibiotics was performed. The constituents of cinnamon, lavender and geranium essential oils were identified by GC-FID-MS analysis, and their Minimal Inhibitory Concentrations (MICs) against tested clinical strains were determined by the micro-dilution broth method. In addition, the effects of essential oils on the viability of human microvascular endothelial cells (HMEC-1) and glioblastoma cell line (T98G) were evaluated. Cinnamon bark oil was the most active against clinical and environmental strains of Acinetobacter baumannii with MIC values ranging from 0.5 to 2.5 µL/mL. The MIC values for geranium oil were between 7.5 and 9.5 µL/mL, and between 10.5 and 13.0 µL/mL for lavender oil. These essential oils can be best employed in the fight against infections caused by bacteria from Acinetobacter genus as components of formulations for hygiene and disinfection of hospital environment.

Paracetamol: mechanism of action, applications and safety concern.

Paracetamol/acetaminophen is one of the most popular and most commonly used analgesic and antipyretic drugs around the world, available without a prescription, both in mono- and multi-component preparations. It is the drug of choice in patients that cannot be treated with non-steroidal anti-inflammatory drugs (NSAID), such as people with bronchial asthma, peptic ulcer disease, hemophilia, salicylate-sensitized people, children under 12 years of age, pregnant or breastfeeding women. It is recommended as a first-line treatment of pain associated with osteoarthritis. The mechanism of action is complex and includes the effects of both the peripheral (COX inhibition), and central (COX, serotonergic descending neuronal pathway, L-arginine/NO pathway, cannabinoid system) antinociception processes and "redox" mechanism. Paracetamol is well tolerated drug and produces few side effects from the gastrointestinal tract, however, despite that, every year, has seen a steadily increasing number of registered cases of paracetamol-induced liver intoxication all over the world. Given the growing problem of the safety of acetaminophen is questioned the validity of the sale of the drug without a prescription. This work, in conjunction with the latest reports on the mechanism of action of paracetamol, trying to point out that it is not a panacea devoid of side effects, and indeed, especially when is taken regularly and in large doses (> 4 g/day), there is a risk of serious side effects.

[The neuroprotective effect of PACAP, VIP, and derivatives in brain ischemia]. / Dzialanie neuroprotekcyjne PACAP, VIP oraz pochodnych w niedokrwieniu mózgu.

Nowadays, stroke is the most frequent cause of adult disability and death of the elderly. In most cases, the etiology of stroke involves cerebral ischemia. Ischemia-induced changes in the brain tissue lead not only to its degeneration, but also to significant activation of cellular mechanisms which protect the affected cells from damage. One such mechanism is the expression of endogenous neuroprotective substances, for example pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intenstinal peptide (VIP), whose properties were investigated recently. PACAP and VIP are neuropeptides widely distributed in both the central nervous system and peripheral organs of various vertebrates. They display pleiotropic biological activity. An extremely strong neuroprotective potential of these peptides has been observed and confirmed in numerous animal models. The protective mechanism of PACAP and VIP involves many intracellular pathways, which can be generally classified into four categories of action: antiapoptotic, anti-inflammatory, metabolic, and modulation of gene expression. Numerous data provided by many research centers suggest that endo- and exogenous PACAP and VIP, as well as their synthetic derivatives, reveal considerable neuroprotective and anti-inflammatory potential, suggesting a possibility of their use as new therapeutic strategies in stroke treatment.

Effects of PACAP, VIP and related peptides on cyclic AMP formation in rat neuronal and astrocyte cultures and cerebral cortical slices.

The effects of pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP), peptide histidine-isoleucine (PHI) and peptide histidine-methionine (PHM) on cyclic AMP formation were studied in parallel on rat cerebral cortical slices, primary neuronal cultures and primary glial (astrocyte) cultures. PACAPappeared to be the most potent agent in all biological systems. The rank order of the peptides' potency was as follows: PACAP > VIP > PHI = PHM for cortical slices and neuronal cell cultures, and PACAP >> PHM approximately VIP > PHI for glial cell cultures. The cyclic AMP responses to the tested peptides, especially to PACAP, were distinctly larger in glial cell cultures than in neuronal cell cultures or brain slices. In an additional study, the cyclic AMP response to helodermin and secretin, as well as isoprenaline, histamine and forskolin, were tested in parallel on glial and neuronal cell cultures, and directly compared with the actions of PACAP. Helodermin and isoprenaline showed clearly stronger activity in glial cell cultures, yet their activity was much weaker than that of PACAP, whereas the effect of forskolin was only 2 times larger in glial cells than in neuronal cultures; histamine had no effect in any cell culture, while secretin produced a small but significant effect only in glial cells. The obtained results suggest that the astrocyte compartment of the rat brain may be the main target for such peptides as PACAP, VIP, or structurally related PHI/PHM or helodermin.

Effects of PACAP and VIP on cyclic AMP formation in rat neuronal and astrocyte cultures under normoxic and hypoxic condition.

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) concentration (0.001-1000 nM)-dependently stimulated cyclic AMP production in rat primary neuronal and glial cell (astrocyte) cultures. The actions of both peptides were much more pronounced in astrocytes than in neuronal cultures. Stimulatory effects of PACAP and VIP on cyclic AMP formation were significantly smaller in cell cultures subjected to 24h lasting hypoxic conditions, induced either chemically (100 microM cobalt chloride) or by low 3% oxygen hypoxia, compared to the normoxic condition (95% air and 5% CO(2)). This picture contrasted with the effects of forskolin that were similar under normoxic and hypoxic conditions. It is suggested that hypoxia leads to changes in PACAP- and VIP-driven cyclic AMP-dependent signaling in the rat brain by influencing molecular processes likely occurring at the level of receptor protein or receptor-Gs protein coupling.

PACAP, VIP, and PHI: effects on AC-, PLC-, and PLD-driven signaling systems in the primary glial cell cultures.

Pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP), and peptide histidine-isoleucine (PHI) are members of a superfamily of structurally related peptides widely distributed in the body and displaying pleiotropic biological activities. All these peptides are known to act via common receptors-VPAC1 and VPAC2. In addition, the effects of PACAP are mediated through its specific receptor named PAC1. The main signal transduction pathway of the mentioned receptors is adenylyl cyclase (AC)-->cAMP system. PACAP and VIP may also signal through receptor-linked phospholipase C (PLC)-->IP3/DAG-->PKC and phospholipase D (PLD)-->phosphatidic acid (PA) pathways. In the present article, we have studied the effects of PACAP, VIP, and PHI (0.001-5000 nM) on the AC-, PLC-, and PLD-driven signaling pathways in rat primary glial cell (astrocytes) cultures. All tested peptides dose-dependently and strongly stimulated cyclic adenosine 3',5'-monophosphate (cAMP) production in this experimental model, displaying the following rank order of potency: PACAP >> VIP > or = PHI. Their effects on PLC-IP3/DAG were weaker, while only PACAP and VIP (0.1-5 microM) significantly stimulated PLD activity. The obtained results showed that rat cerebral cortex-derived astrocytes are responsive to PACAP, VIP and PHI/PHM and possess PAC1 and likely VPAC-type receptors linked to activation of AC-cAMP-, PLC-IP3/DAG-, and PLD-PA signaling systems.