In the CNS, glutamate is the most abundant excitatory neurotransmitter. Thought to play a major role in learning, memory and overall neural development, the ionotropic glutamate receptor (iGluR) family of ligand-gated ion channels includes AMPA receptors, which mediate fast synaptic depolarization, NMDA receptors, which mediate cation flow (importantly, Ca2+), as well as kainate receptors. Different functions for each of these family members implies differential regulation. This research focuses on understanding and differentiating receptor regulation for use in conditions such as Alzheimer's and Parkinson's disease as well as stroke.

Data will be presented aimed at explaining the differential regulation of NMDA receptors by the endogeneous neurosteroids pregnenalone sulfate (PS) and 3a-hydroxy-5ß-pregnan-20-one sulfate (PregaS). NMDA receptors are heterotetramers composed of NR1 and NR2 subunits. Recent findings from our lab have shown that neither of these neurosteroids bind to the NMDA NR1 subunits. Our focus is therefore directed towards determining the neurosteroid binding domain(s) on the NR2 subunits. Interestingly, the capsaicin receptor, another non-selective cation channel, has also been shown to be regulated by PS. To aid in identification of the PS and PregaS binding sites on the NMDA NR2 subunits, the location of these binding sites on the capsaicin receptor are also being pursued. Data will be presented which demonstrates the cloning, over-expression, and partial purification of both the NMDA NR2B and D subunits as well as the capsaicin receptor extracellular domain. In addition, preliminary neurosteroid binding studies of the NR2-B and D subunits will be presented.