Steroids are synthesized in the CNS, exert profound modulatory effects of receptors for amino acid neurotransmitters, and may act as endogenous modulators of synaptic activity. Abnormal activation of amino acid receptors has been proposed to play a role in the etiology of a variety of psychiatric disorders such as anxiety, depression, and schizophrenia, and to contribute to neuronal damage associated with stroke, seizures, neuropathic pain, trauma, and neurodegenerative disease (such as Parkinson's and Alzheimer's). In following up our original discovery that pregnenolone sulfate (PS), an abundant neurosteroid, modulates glutamate receptors, we have identified a variety of steroids that can potentiate (by up to 10-fold) or inhibit glutamate receptor function and exacerbate or protect against NMDA-induced death of hippocampal neurons in culture. One inhibitor compound, pregnanolone hemisuccinate, works in vivo to reduce middle cerebral artery occlusion-induced degeneration of cortical and subcortical nervous tissue. A major objective of this project will be to test our working hypothesis that steroids interact with the extracellular domain of individual receptor subunits and exert their effects by regulating the balance between excitation and inhibition between CNS neurons. Toward this end, novel steroids will be synthesized and evaluated electrophysiologically (using whole-cell and two-electrode voltage clamp) to test specific structure-activity hypotheses and to evaluate the modulatory effects of steroids on native glutamate receptors in primary rat hippocampal neurons and on homomeric receptors expressed in Xenopus oocytes. Initial results that steroids can discriminate among glutamate receptor subtypes will be extended to search for more highly selective compounds. The effects of steroids on receptor chimeras and on receptors with single amino acid substitutions will be examined to identify specific amino acids essential for ligand recognition. Novel steroids will be evaluated for their ability to inhibit EAA-induced increases in cytosolic free [Ca2+] (using Fluo-3 fluorescence as an indicator) and excitotoxic neuronal death. Collectively these experiments will add to our understanding of the molecular mechanisms whereby steroids modulate EAAR function, and to the development of neuroprotective agents and cognitive enhancers.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
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Neuropharmacology and Neurochemistry Review Committee (NPNC)
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Winsky, Lois M
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Boston University
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Smith, Conor C; Martin, Stella C; Sugunan, Kavitha et al. (2014) A role for picomolar concentrations of pregnenolone sulfate in synaptic activity-dependent Ca2+ signaling and CREB activation. Mol Pharmacol 86:390-8
Smith, Conor C; Gibbs, Terrell T; Farb, David H (2014) Pregnenolone sulfate as a modulator of synaptic plasticity. Psychopharmacology (Berl) 231:3537-56
Kostakis, Emmanuel; Smith, Conor; Jang, Ming-Kuei et al. (2013) The neuroactive steroid pregnenolone sulfate stimulates trafficking of functional N-methyl D-aspartate receptors to the cell surface via a noncanonical, G protein, and Ca2+-dependent mechanism. Mol Pharmacol 84:261-74
Kostakis, Emmanuel; Jang, Ming-Kuei; Russek, Shelley J et al. (2011) A steroid modulatory domain in NR2A collaborates with NR1 exon-5 to control NMDAR modulation by pregnenolone sulfate and protons. J Neurochem 119:486-96
Eagleson, K L; Gravielle, M C; Schlueter McFadyen-Ketchum, L J et al. (2010) Genetic disruption of the autism spectrum disorder risk gene PLAUR induces GABAA receptor subunit changes. Neuroscience 168:797-810
Berezhnoy, D; Gibbs, T T; Farb, D H (2009) Docking of 1,4-benzodiazepines in the alpha1/gamma2 GABA(A) receptor modulator site. Mol Pharmacol 76:440-50
Berezhnoy, Dmytro; Gravielle, Maria C; Downing, Scott et al. (2008) Pharmacological Properties of DOV 315,090, an ocinaplon metabolite. BMC Pharmacol 8:11
Sadri-Vakili, G; Janis, G C; Pierce, R C et al. (2008) Nanomolar concentrations of pregnenolone sulfate enhance striatal dopamine overflow in vivo. J Pharmacol Exp Ther 327:840-5
Whittaker, Matthew T; Gibbs, Terrell T; Farb, David H (2008) Pregnenolone sulfate induces NMDA receptor dependent release of dopamine from synaptic terminals in the striatum. J Neurochem 107:510-21
Jang, Ming-Kuei; Mierke, Dale F; Russek, Shelley J et al. (2004) A steroid modulatory domain on NR2B controls N-methyl-D-aspartate receptor proton sensitivity. Proc Natl Acad Sci U S A 101:8198-203

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