G protein-biased LPAR1 agonism of prototypic antidepressants: Implication in the identification of novel therapeutic target for depression.

Prototypic antidepressants, such as tricyclic/tetracyclic antidepressants (TCAs), have multiple pharmacological properties and have been considered to be more effective than newer antidepressants, such as selective serotonin reuptake inhibitors, in treating severe depression. However, the clinical contribution of non-monoaminergic effects of TCAs remains elusive. In this study, we discovered that amitriptyline, a typical TCA, directly binds to the lysophosphatidic acid receptor 1 (LPAR1), a G protein-coupled receptor, and activates downstream G protein signaling, while exerting a little effect on β-arrestin recruitment.

Serum levels of high mobility group box-1 protein (HMGB1) and soluble receptors of advanced glycation end-products (RAGE) in depressed patients treated with electroconvulsive therapy.

Aims: High mobility group box-1 (HMGB1) is one of the damage-associated molecular patterns produced by stress and induces inflammatory responses mediated by receptors of advanced glycation end-products (RAGE) on the cell surface. Meanwhile, soluble RAGE (sRAGE) exhibits an anti-inflammatory effect by capturing HMGB1. Animal models have shown upregulation of HMGB1 and RAGE in the brain or blood, suggesting the involvement of these proteins in depression pathophysiology.

Tetraspanin heterogeneity of small extracellular vesicles in human biofluids and brain tissue.

Extracellular vesicles (EVs) are particles released from most cell types delimited by a lipid bilayer. Small EVs (sEVs) are nanosized (<200 nm) and include exosomes. Brain-derived sEVs may provide a source for new biomarkers of brain status.

Reduced Cerebrospinal Fluid Levels of Lysophosphatidic Acid Docosahexaenoic Acid in Patients With Major Depressive Disorder and Schizophrenia.

Background: Lysophosphatidic acid (LPA) is involved in numerous biological processes, including neurodevelopment, chronic inflammation, and immunologic response in the central nervous system. Autotaxin (ATX) is a secreted enzyme that produces LPA from lysophosphatidylcholine (LPC). Previous studies have demonstrated decreased protein levels of ATX in cerebrospinal fluid (CSF) of patients with major depressive disorder (MDD).

Lysophosphatidic acid induces thrombospondin-1 production in primary cultured rat cortical astrocytes.

Lysophosphatidic acid (LPA), a brain membrane-derived lipid mediator, plays important roles including neural development, function, and behavior. In the present study, the effects of LPA on astrocyte-derived synaptogenesis factor thrombospondins (TSPs) production were examined by real-time PCR and western blotting, and the mechanism underlying this event was examined by pharmacological approaches in primary cultured rat cortical astrocytes. Treatment of astrocytes with LPA increased TSP-1 mRNA, and TSP-2 mRNA, but not TSP-4 mRNA expression.

Differential anatomical and cellular expression of lysophosphatidic acid receptor 1 in adult mouse brain.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that acts as an extracellular signaling molecule through six G-protein-coupled receptors: LPA-LPA. Recent studies have demonstrated that LPA signaling via LPA receptor plays a crucial role in cognition and emotion. However, because of limited availability of reliable antibodies, it is currently difficult to identify the cell types expressing LPA receptor in the brain.

Increased matrix metalloproteinases in cerebrospinal fluids of patients with major depressive disorder and schizophrenia.

Background: Chronic inflammation of the brain has a pivotal role in the pathophysiology of major depressive disorder (MDD) and schizophrenia (SCZ). Matrix metalloproteinases (MMPs) are extracellular proteases involved in pro-inflammatory processes and interact with IL-6, which is increased in the cerebrospinal fluid (CSF) of patients with MDD and SCZ. However, MMPs in the CSF in patients with MDD and SCZ remains unclear.

Decreased serum levels of thrombospondin-1 in female depressed patients.

Aim: Thrombospondin-1 (TSP-1) is an astrocyte-derived synaptogenesis-related factor. It was previously reported to be increased by chronic treatment of electroconvulsive seizure, a model of electroconvulsive therapy (ECT), in rat hippocampus. The aim of this study was to examine whether serum levels of TSP-1 are associated with depression and ECT.

Shared preventive factors associated with relapse after a response to electroconvulsive therapy in four major psychiatric disorders.

Aim: The efficacy of electroconvulsive therapy (ECT) has been established in psychiatric disorders but the high rate of relapse is a critical problem. The current study sought preventative factors associated with relapse after a response to ECT in a continuum of four major psychiatric disorders.

Methods: The records of 255 patients with four psychiatric disorders (83 unipolar depression, 60 bipolar depression, 91 schizophrenia, 21 schizoaffective disorder) were retrospectively reviewed.

Antidepressant amitriptyline-induced matrix metalloproteinase-9 activation is mediated by Src family tyrosine kinase, which leads to glial cell line-derived neurotrophic factor mRNA expression in rat astroglial cells.

Background: Astrocytes have been implicated in the pathophysiology of mood disorders and in the mechanism of the pharmacological effects of antidepressant drugs by the production of neurotrophic/growth factors. Previous studies have identified astrocyte-expressed Gα -coupled lysophosphatidic acid receptor 1 (LPAR1), as being involved in antidepressant-induced production of glial cell line-derived neurotrophic factor (GDNF) and matrix metalloproteinase-9 (MMP-9) activation, an important step in the production of GNDF. However, the precise mechanism of MMP-9 activation by antidepressants has yet to be identified, in particular the intracellular signaling pathway between LPAR1/Gα and MMP-9.

Possible Association between Serum Matrix Metalloproteinase-9 (MMP-9) Levels and Relapse in Depressed Patients following Electroconvulsive Therapy (ECT).

Background: Matrix metalloproteinases are involved in neuroinflammatory processes, which could underlie depression. Serum levels of MMP-9 and MMP-2 in depressed patients are significantly altered following electroconvulsive therapy, but an association between altered matrix metalloproteinases after successful ECT and possible relapse has yet to be investigated.

Methods: Serum was obtained twice, before and immediately after a course of electroconvulsive therapy, from 38 depressed patients.

Identification of Lysophosphatidic Acid Receptor 1 in Astroglial Cells as a Target for Glial Cell Line-derived Neurotrophic Factor Expression Induced by Antidepressants.

Preclinical and clinical evidence suggests that glial cell line-derived neurotrophic factor (GDNF) is important in the therapeutic effect of antidepressants. A previous study demonstrated that the tricyclic antidepressant amitriptyline induces Gα activation, which leads to GDNF expression in astrocytes. However, the specific target expressed in astrocytes that mediates antidepressant-evoked Gα activation has yet to be identified.

Factors associated with relapse after a response to electroconvulsive therapy in unipolar versus bipolar depression.

Background: While electroconvulsive therapy (ECT) treatment for depression is highly effective, the high rate of relapse is a critical problem. The current study investigated factors associated with the risk of relapse in mood disorders in patients in which ECT was initially effective.

Method: The records of 100 patients with mood disorders (61 unipolar depression, 39 bipolar depression) who received and responded to an acute ECT course were retrospectively reviewed.

The expression of glial cell line-derived neurotrophic factor mRNA by antidepressants involves matrix metalloproteinase-9 activation in rat astroglial cells.

Neurotrophic/growth factors derived from glial cells, especially astrocytes, have been implicated in mood disorders and the pharmacological effects of antidepressant drugs. Previous studies demonstrated that the release of glial cell line-derived neurotrophic factor (GDNF) induced by the tricyclic antidepressant amitriptyline was significantly inhibited by a broad-spectrum matrix metalloproteinase (MMP) inhibitor in rat C6 astroglial cells (C6 cells). However, it is unknown whether amitriptyline affects MMP enzymatic activity or expression, and the MMP subtype has yet to be identified.

Altered Serum Levels of Matrix Metalloproteinase-2, -9 in Response to Electroconvulsive Therapy for Mood Disorders.

Background: Inflammatory processes could underlie mood disorders. Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMP) are inflammation-related molecules. The current study sought an association between mood disorders and systemic levels of MMPs and TIMPs.

Fibroblast growth factor 2 mRNA expression evoked by amitriptyline involves extracellular signal-regulated kinase-dependent early growth response 1 production in rat primary cultured astrocytes.

Recently, we demonstrated that several antidepressants including amitriptyline increased fibroblast growth factor 2 (FGF2) mRNA expression slowly over 24 h through de novo protein synthesis in rat primary cultured astrocytes. This study defined the signaling cascade that mediates amitriptyline-induced FGF2 production in rat primary cultured astrocytes. Amitriptyline treatment significantly increased early growth response 1 (EGR1), a transcription factor known to regulate FGF2 expression.

Tricyclic Antidepressant Amitriptyline-induced Glial Cell Line-derived Neurotrophic Factor Production Involves Pertussis Toxin-sensitive Gαi/o Activation in Astroglial Cells.

Further elaborating the mechanism of antidepressants, beyond modulation of monoaminergic neurotransmission, this study sought to elucidate the mechanism of amitriptyline-induced production of glial cell line-derived neurotrophic factor (GDNF) in astroglial cells. Previous studies demonstrated that an amitriptyline-evoked matrix metalloproteinase (MMP)/FGF receptor (FGFR)/FGFR substrate 2α (FRS2α)/ERK cascade is crucial for GDNF production, but how amitriptyline triggers this cascade remains unknown. MMP is activated by intracellular mediators such as G proteins, and this study sought to clarify the involvement of G protein signaling in amitriptyline-evoked GDNF production in rat C6 astroglial cells (C6 cells), primary cultured rat astrocytes, and normal human astrocytes.

Sigma-1 receptor concentration in plasma of patients with late-life depression: a preliminary study.

Background: Recently, the sigma-1 receptor has been shown to play a significant role in the neural transmission of mood by regulating N-methyl-D-aspartate receptors. Additionally, the sigma-1 receptor has been reported to influence cognitive functions including learning and memory. In this study, we measured plasma sigma-1 receptor concentrations before and after antidepressant treatment in patients with late-life major depressive disorder (MDD) and explored whether changes in depressive status are related to sigma-1 receptor concentrations.

Electroconvulsive seizure induces thrombospondin-1 in the adult rat hippocampus.

Synaptic dysfunction has recently gained attention for its involvement in mood disorders. Electroconvulsive therapy (ECT) possibly plays a role in synaptic repair. However, the underlying mechanisms remain uncertain.

Antidepressant acts on astrocytes leading to an increase in the expression of neurotrophic/growth factors: differential regulation of FGF-2 by noradrenaline.

Recently, multiple neurotrophic/growth factors have been proposed to play an important role in the therapeutic action of antidepressants. In this study, we prepared astrocyte- and neuron-enriched cultures from the neonatal rat cortex, and examined the changes in neurotrophic/growth factor expression by antidepressant treatment using real-time PCR. Treatment with amitriptyline (a tricyclic antidepressant) significantly increased the expression of fibroblast growth factor-2 (FGF-2), brain-derived neurotrophic factor, vascular endothelial growth factor and glial cell line-derived neurotrophic factor mRNA with a different time course in astrocyte cultures, but not in neuron-enriched cultures.