Keywords:
Animal Models
Development
Learning
Memory
Molecular biology
Neuronal plasticity
Neuropharmacology
Schizophrenia
Signal transduction

Detailed Description: Our laboratory has a long-standing interest in the development of new therapies for psychiatric disease. Our approach to this problem has been to use mouse models to understand how susceptibility genes alter brain function, and to test genetic and pharmacological interventions for their ability to normalize brain function. As a graduate student I developed a line of mice that has reduced levels of NMDA receptors. For the past 15 years, these mice have afforded many laboratories, including my own, the ability to study the consequences of NMDA receptor dysfunction in vivo. We generated the first genetic model to test the glutamate hypothesis of schizophrenia and to search for new therapies.

Currently, we are testing several hypotheses about the neural substrates of psychosis. First, we believe that a core feature of schizophrenia is the reduction in glutamatergic synapses and dendritic spine density. Based on this hypothesis, we are studying the molecular mechanisms by which reduced NMDA receptor function ultimately leads to a loss of spines. We are now testing whether manipulations of RhoGTPase signaling will improve the behavioral impairments of NMDA receptor knockdown mice through changes in spine density.

We also hypothesize that psychosis results from a loss of dynamic range in dopamine signaling. We are testing this hypothesis with the use of pharmacologic and genetic interventions that modulate dopamine neuron firing patterns and signaling. This work will provide fundamental insights into the way that dopamine neuron dysregulation translates into psychosis. Our approach is to use Cre/lox technologies to achieve dopamine-selective rescue of NMDA receptor levels and examine which behavioral abnormalities are restored as a consequence of intrinsic dopamine neuron activity.

Third, we are studying the developmental consequences of NMDA receptor dysfunction. We are working to determine how much of the pathology that results from NMDA receptor dysfunction is due to miswiring of neural circuits, and whether the adult brain has sufficient plasticity to properly rewire. Our studies use a tamoxifen-inducible Cre system to restore NMDA receptor levels at different developmental stages. We have discovered that the plasticity of schizophrenia-relevant behaviors may be more dependent on brain region and neural circuit than on developmental age.

METHODS USED:

Neurons, Adenovirus, Behavioral tests, Elisa, Gene expression analysis, Immunohistochemistry, Immunocytochemistry, qRT-PCR, RT-PCR, Signal transduction characterization, Western blot

EQUIPMENT:

Analytical balances, benchtop centrifuge, blotting apparatus, culture hood, culture incubators, cryostat , departmental beta and gamma counters, dissecting microscope, fluorescence microscope, fresh tissue sectioning systems, gel apparatus, low- and high-speed centrifuge, low and ultralow freezers, real-time/thermocycler, vibratome, water baths
 

PRESENT TRAINEES                                                                                                        

Rehnuma Islam

PRESENT COLLABORATIONS

Evelyn Lambe
Lu-Yang Wang

Outside the Department of Physiology:

Richard Bazinet, Nutritional Sciences, University of Toronto

Stephanie Borgland, Hotchkiss Brain Institute, University of Calgary

Carrie Jones, Vanderbilt University, USA

Craig Lindsley, Vanderbilt University, USA

Sara Jones, Physiology and Pharmacology, Wake Forest University, USA

Liza Barki-Harrington, Haifa University, Israel

Committee Member or Officer of national/international scientific organizations

GRANT COMMITTEES (CURRENTLY SERVING)

Agency: CIHR

Committee: BSA Panel: Operating Grant & Foundation Scheme