EXCEED THE SPACE PROVIDED. Epilepsy is a debilitating disease that affects 1-2% of the population. Anticonvulsant drug therapy is the treatment of choice, however about 30% of epilepsies are intractable to drug therapy, and necessitate surgical removal of brain tissue. In addition, anticonvulsant drugs reduce neuronal excitability non-specifically throughout the brain, leading to sedation and somnolence as side effects. Thus, there is an ongoing need to develop new anti-epileptic drugs. The overall goals of the proposed research are to help develop new anti-epileptic drug therapies by investigating the mechanisms of a new class of anticonvulsant drugs, the neurosteroids. Neurosteroids are synthesized in the brain, and regulate neuronal excitability by modulating GABAA receptors (the major inhibitory neurotransmitter receptors in the brain). Synthethic neurosteroids have proven to be effective anti-epileptic drugs in clinical trials, even against otherwise drug resistant epilepsies. Moreover, neurosteroids can potentially be engineered for greater specificity, to reduce side-effects. Two approaches will be taken to better understand neurosteroid modulation of GABAA receptors. First, to gain fundamental insights into neurosteroid mechanisms, a simple, well characterized steroid-receptor interaction will be studied: The inhibition of the C. elegans UNC-49 receptor by pregnenolone sulfate (PS). Rapid ligand exchange methods will be used to characterize the mechanism of PS modulation of UNC-49, and to determine how the key residues act as effectors of PS modulation. Results of this study will be applicable to understanding neurosteroid modulation in humans because UNC-49 is a highly conserved GABAA receptor homolog. Second, the unique pharmacological properties of UNC-49 will be exploited in domain swap experiments to directly identify residues important for neurosteroid modulation in human GABAA receptors. The results of both approaches will increase understanding of how endogenous neurosteroids regulate seizure susceptibility, and will aid the design of new anti-epileptic drugs. PERFORMANCE SITE ========================================Section End===========================================

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS043345-03
Application #
6823249
Study Section
Special Emphasis Panel (ZRG1-BDCN-2 (01))
Program Officer
Stewart, Randall R
Project Start
2002-12-15
Project End
2006-11-30
Budget Start
2004-12-01
Budget End
2005-11-30
Support Year
3
Fiscal Year
2005
Total Cost
$284,050
Indirect Cost
Name
University of Utah
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
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Davis, Kathleen M; Sturt, Brianne L; Friedmann, Andrew J et al. (2010) Regulated lysosomal trafficking as a mechanism for regulating GABAA receptor abundance at synapses in Caenorhabditis elegans. Mol Cell Neurosci 44:307-17
Twede, Vernon; Tartaglia, Anthony L; Covey, Douglas F et al. (2007) The neurosteroids dehydroepiandrosterone sulfate and pregnenolone sulfate inhibit the UNC-49 GABA receptor through a common set of residues. Mol Pharmacol 72:1322-9
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