The class of neurotransmitter receptor molecules activated by L-glutamate appears to mediate most fast synaptic transmission in the vertebrate central nervous system. The broad objective of the project described here is to further our pharmacological and biophysical understanding of how this important class of receptors is activated and regulated. Glutamate receptors function in nearly every category of normal central nervous system activity. There is evidence for their involvement at multiple levels in sensory and motor systems. Glutamate receptors are found at high density in the cortex and appear to be essential for higher functions such as learning and memory. They also play important roles in brain dysfunction; glutamate receptors have been implicated in the etiology of many brain disorders including epilepsy, Alzheimer's disease, Huntington's disease, and schizophrenia. In addition, hypoxia induced neuronal death, as a consequence, for example, of stroke, may result from excessive activation of glutamate receptors. A description of either normal or pathological brain function will require detailed understanding of how glutamate receptors work. The research proposed here is intended to advance that understanding. Specifically, five major goals will be pursued: 1) New drugs active at glutamate receptor sites will be characterized; 2) the kinetics of receptor binding by a class of drugs that modulate one type of glutamate response will be measured; 3) the speed with which glutamate leaves one of its receptor sites will be measured; 4) the variation in glutamate receptor properties in different parts of the brain will be studied, and 5) the mechanisms by which glutamate responses can be regulated will be investigated. The responses of neurons and of single receptor-channel complex molecules will be studied with the electrophysiological technique of patch clamp in combination with a perfusion technique that allows rapid extracellular solution changes. The research plan will provide considerable scientific development for the Principal Investigator. Powerful and broadly applicable new techniques for the patch clamp study of intact neurons in brain slices will be developed. Investigation of the long-term regulation of glutamate responses will broaden the research perspective of the Principal Investigator into a major field of membrane channel research. This project can contribute to the understanding of how neurons communicate, and to the development of pharmacologically and therapeutically useful drugs. The knowledge gained should help provide insight into the mechanisms that underlie the wide variety of physiological processes and brain disorders in which glutamate receptors are involved.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Scientist Development Award - Research (K02)
Project #
5K02MH000944-05
Application #
2240184
Study Section
Research Scientist Development Review Committee (MHK)
Project Start
1991-09-30
Project End
1996-08-31
Budget Start
1995-09-01
Budget End
1996-08-31
Support Year
5
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Qian, Anqi; Johnson, Jon W (2006) Permeant ion effects on external Mg2+ block of NR1/2D NMDA receptors. J Neurosci 26:10899-910
Qian, Anqi; Buller, Amy L; Johnson, Jon W (2005) NR2 subunit-dependence of NMDA receptor channel block by external Mg2+. J Physiol 562:319-31
Blanpied, Thomas A; Clarke, Richard J; Johnson, Jon W (2005) Amantadine inhibits NMDA receptors by accelerating channel closure during channel block. J Neurosci 25:3312-22
Qian, Anqi; Johnson, Jon W (2002) Channel gating of NMDA receptors. Physiol Behav 77:577-82
Qian, Anqi; Antonov, Sergei M; Johnson, Jon W (2002) Modulation by permeant ions of Mg(2+) inhibition of NMDA-activated whole-cell currents in rat cortical neurons. J Physiol 538:65-77
Li-Smerin, Y; Levitan, E S; Johnson, J W (2001) Free intracellular Mg(2+) concentration and inhibition of NMDA responses in cultured rat neurons. J Physiol 533:729-43
Li-Smerin, Y; Aizenman, E; Johnson, J W (2000) Inhibition by intracellular Mg(2+) of recombinant N-methyl-D-aspartate receptors expressed in Chinese hamster ovary cells. J Pharmacol Exp Ther 292:1104-10
Antonov, S M; Gmiro, V E; Johnson, J W (1998) Binding sites for permeant ions in the channel of NMDA receptors and their effects on channel block. Nat Neurosci 1:451-61
Dilmore, J G; Johnson, J W (1998) Open channel block and alteration of N-methyl-D-aspartic acid receptor gating by an analog of phencyclidine. Biophys J 75:1801-16
Blanpied, T A; Boeckman, F A; Aizenman, E et al. (1997) Trapping channel block of NMDA-activated responses by amantadine and memantine. J Neurophysiol 77:309-23

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