ABSTRACT
Increasing evidence suggests that clock genes may be implicated in a spectrum of psychiatric diseases, including sleep and mood related disorders as well as schizophrenia. The bHLH transcription factors SHARP1/DEC2/BHLHE41 and SHARP2/DEC1/BHLHE40 are modulators of the circadian system and SHARP1/DEC2/BHLHE40 has been shown to regulate homeostatic sleep drive in humans. In this study, we characterized Sharp1 and Sharp2 double mutant mice (S1/2-/-) using online EEG recordings in living animals, behavioral assays and global gene expression profiling. EEG recordings revealed attenuated sleep/wake amplitudes and alterations of theta oscillations. Increased sleep in the dark phase is paralleled by reduced voluntary activity and cortical gene expression signatures reveal associations with psychiatric diseases. S1/2-/- mice display alterations in novelty induced activity, anxiety and curiosity. Moreover, mutant mice exhibit impaired working memory and deficits in prepulse inhibition resembling symptoms of psychiatric diseases. Network modeling indicates a connection between neural plasticity and clock genes, particularly for SHARP1 and PER1. Our findings support the hypothesis that abnormal sleep and certain (endo)phenotypes of psychiatric diseases may be caused by common mechanisms involving components of the molecular clock including SHARP1 and SHARP2.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/deficiency , Circadian Rhythm/physiology , Endophenotypes/metabolism , Mental Disorders/physiopathology , Repressor Proteins/deficiency , Sleep/physiology , Transcription Factors/deficiency , Animals , Anxiety/complications , Anxiety/physiopathology , Basic Helix-Loop-Helix Transcription Factors/genetics , Basic Helix-Loop-Helix Transcription Factors/metabolism , Circadian Rhythm/drug effects , Clozapine/pharmacology , Clozapine/therapeutic use , Exploratory Behavior/drug effects , Gene Expression Profiling , Gene Expression Regulation/drug effects , Gene Regulatory Networks , Male , Mental Disorders/complications , Mice, Inbred C57BL , Prepulse Inhibition/drug effects , Repressor Proteins/genetics , Repressor Proteins/metabolism , Sleep/drug effects , Transcription Factors/genetics , Transcription Factors/metabolism , Wakefulness/drug effects , Wakefulness/geneticsABSTRACT
Hypofunction of glutamate receptors may contribute to the symptoms of schizophrenia. Human platelets express glutamate receptors and can serve as peripheral surrogate model for neuronal cells. Aim of this study was to establish a fast and sensitive flow-cytometric method to determine the glutamate-dependent kinetics of intracellular calcium ([Ca++]i) mobilization in platelets of schizophrenic patients. Glutamate stimulated [Ca++]i response was measured with a flow-cytometer in anti-CD-41a-labelled whole blood platelets of treated schizophrenic patients (n=18) and controls (n=18). In two control experiments the NMDA-receptor antagonist MK-801 and the dopamine antagonist amisulpride, respectively, were added to probes from healthy subjects. Stimulation with glutamate led dose-dependently to a mobilization of [Ca++]i in both healthy controls and patients. This effect was significantly reduced in patients. In vitro NMDA-antagonism inhibited the glutamate response, whereas dopamine-antagonism had no effect. Our flow-cytometric method allows to measure glutamate-receptor mediated [Ca++]i response in whole blood platelets, without requiring platelet rich preparations. The reduced glutamate-response in the patients was not explained by a direct inhibitory treatment effect. However, further studies with drug naive patients will be necessary to find out whether or not the observed hypoglutamergic function of platelets is endogenous to the disorder.
Subject(s)
Blood Platelets/metabolism , Flow Cytometry/methods , Receptors, Glutamate/blood , Schizophrenia/blood , Adult , Amisulpride , Analysis of Variance , Blood Platelets/drug effects , Calcium/blood , Dizocilpine Maleate/blood , Dopamine Antagonists/blood , Dose-Response Relationship, Drug , Excitatory Amino Acid Antagonists/blood , Female , Humans , Intracellular Membranes/drug effects , Intracellular Membranes/metabolism , Male , Middle Aged , Pilot Projects , Reference Values , Reproducibility of Results , Sensitivity and Specificity , Sulpiride/analogs & derivatives , Sulpiride/blood , Young AdultABSTRACT
Embryonic stem cells (ES) are pluripotent and may therefore serve as a source for the generation of specific cell types required for future therapies based on cell replacement. The isolation of defined cell populations from a certain lineage or tissue is a prerequisite for the analysis of the potential of such ES-derived cells in animal transplantation studies. Here, using the Cre/loxP system, we report the generation of murine ES cells conditionally expressing the hrGFP gene at the cell surface. Such ES cells can be differentiated in vitro into neurons displaying GFP activity in neurites. Transgenic mice derived from these ES cells permit the targeting of GFP-expression to specific tissues and provide material from the three germ layers suitable for molecular and biochemical analysis.
