PT - JOURNAL ARTICLE AU - Mijeong Park-Chung AU - Fong-Sen Wu AU - Robert H. Purdy AU - Andrew A. Malayev AU - Terrell T. Gibbs AU - David H. Farb TI - Distinct Sites for Inverse Modulation of<em>N</em>-Methyl-<span class="sc">d</span>-Aspartate Receptors by Sulfated Steroids AID - 10.1124/mol.52.6.1113 DP - 1997 Dec 01 TA - Molecular Pharmacology PG - 1113--1123 VI - 52 IP - 6 4099 - http://molpharm.aspetjournals.org/content/52/6/1113.short 4100 - http://molpharm.aspetjournals.org/content/52/6/1113.full SO - Mol Pharmacol1997 Dec 01; 52 AB - Steroid sulfation occurs in nervous tissue and endogenous sulfated steroids can act as positive or negative modulators ofN-methyl-d-aspartate (NMDA) receptor function. In the current study, structure-activity relationships for sulfated steroids were examined in voltage-clamped chick spinal cord and rat hippocampal neurons in culture and in Xenopus laevis oocytes expressing NR1100 and NR2A subunits. The ability of pregnenolone sulfate (a positive modulator) and epipregnanolone sulfate (a negative modulator) to compete with each another, as well as with other known classes of NMDA receptor modulators, was examined. The results show that steroid positive and negative modulators act at specific, extracellularly directed sites that are distinct from one another and from the spermine, redox, glycine, Mg2+, MK-801, and arachidonic acid sites. Sulfated steroids are effective as modulators of ongoing glutamate-mediated synaptic transmission, which is consistent with their possible role as endogenous neuromodulators in the CNS.