Charles E. Spivak

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Binding of the neurosteroid dehydroepiandrosterone sulfate (DHEAS) to rat brain synaptosomal membranes was studied in vitro, and the interaction of DHEAS with the GABAA receptor was tested using biochemical and electrophysiological assays. DHEAS bound to two populations of sites, and its binding was inhibited by barbiturates. DHEAS interfered with(More)
Isoarecolone methiodide has been reported previously to be a potent agonist at peripheral nicotinic-cholinergic receptors. Both isoarecolone methiodide and isoarecolone HCl can produce contractures of the frog rectus abdominis muscle and can inhibit binding of [3H]-(-)-nicotine to rat brain membranes, although the methiodide is much more potent than the(More)
BACKGROUND Stromal-Derived Inducing Activity (SDIA) is one of the most efficient methods of generating dopaminergic (DA) neurons from embryonic stem cells (ESC). DA neuron induction can be achieved by co-culturing ESC with the mouse stromal cell lines PA6 or MS5. The molecular nature of this effect, which has been termed "SDIA" is so far unknown. Recently,(More)
Dehydroepiandrosterone sulfate (DHEAS) blocked the GABAA receptor noncompetitively in neurons grown in primary culture from the ventral midbrains of fetal rats. The apparent dissociation constant for this blockade was 4.5 microM, and one molecule of DHEAS was sufficient to block the receptor. The affinity of the blocked receptor for GABA was diminished by(More)
mu opiate receptors recognize morphine with high affinity. A 2.1-kb rat brain cDNA whose predicted translation product displays 63% identity with recently described delta and kappa opiate receptor sequences was identified through polymerase chain reaction and cDNA homology approaches. This cDNA recognizes a 10.5-kb mRNA that is expressed in thalamic(More)
Recently we demonstrated that [3H]dehydroepiandrosterone sulfate binds specifically to two populations of sites in rat brain membranes [Majewska et al. (1990) Eur. J. Pharmac. 189, 307-315]. As an extension of this work, we studied the biochemical and pharmacological properties of [3H]dehydroepiandrosterone sulfate binding to brain membranes and the effects(More)
1. The rho 1 protein, which we previously cloned from retina, assembles as a homooligomer that transduces the binding of gamma-aminobutyric acid (GABA) into robust chloride currents. However, its insensitivity to bicuculline, pentobarbitone and benzodiazepines, all potent agents at typical GABAA receptors, suggested that it may react atypically to other(More)
The mu-opioid receptor is the principal site of action in the brain by which morphine, other opiate drugs of abuse, and endogenous opioid peptides effect analgesia and alter mood. A member of the seven-transmembrane domain (TM) G protein-coupled receptor (GPCR) superfamily, the mu-opioid receptor modulates ion channels and second messenger effectors in an(More)
Isoarecolone methiodide (1-methyl-4-acetyl-1,2,3,6-tetrahydropyridine methiodide) was previously shown to be among the most potent agonists tested at the frog neuromuscular junction. Because nicotinic receptors from different sources vary in their selectivities, isoarecolone methiodide as well as 19 additional congeners, most of which were also previously(More)
Various histrionicotoxins tested on frog nerve-muscle preparations showed a qualitative family resemblance to one another. They blocked the nerve-evoked muscle twitch and depressed both the peak amplitudes and the decay time constants of end-plate currents. During repetitive stimulation they progressively decreased the rate of rise and prolonged the falling(More)