Potent mGluR5 antagonists: pyridyl and thiazolyl-ethynyl-3,5-disubstituted-phenyl series.

We report the synthesis of four series of 3,5-disubstituted-phenyl ligands targeting the metabotropic glutamate receptor subtype 5: (2-methylthiazol-4-yl)ethynyl (1a-j,), (6-methylpyridin-2-yl)ethynyl (2a-j), (5-methylpyridin-2-yl)ethynyl (3a-j,), and (pyridin-2-yl)ethynyl (4a-j,). The compounds were evaluated for antagonism of glutamate-mediated mobilization of internal calcium in an mGluR5 in vitro assay. All compounds were found to be full antagonists and exhibited low nanomolar to subnanomolar activity.

Modulation of the basal ganglia by metabotropic glutamate receptors: potential for novel therapeutics.

The basal ganglia are implicated in a number of disorders including neurodegenerative motor diseases such as Huntington's and Parkinson's disease, as well as psychiatric disorders such as schizophrenia and obsessive compulsive disorder. In recent years, a great deal of effort has been focused on determining the basal ganglia circuitry that underlies normal behavior, as well as many of these syndromes. This has led to a detailed understanding of both the normal and pathophysiological flow of information through the basal ganglia, and has provided the opportunity to begin developing novel pharmacological methods of intervention by targeting neuromodulatory receptors with in the basal ganglia circuit. One group of receptors that holds much promise for several basal ganglia disorders is the metabotropic glutamate receptors. Data from behavioral, neurochemical, neuroanatomical and electrophysiological studies has begun to reveal the functional roles that the metabotropic glutamate receptors play in modulating the basal ganglia circuit, and suggests that compounds selectively targeting these receptors may provide novel therapies for a variety of disorders including Parkinson's disease, addiction, and epilepsy.

Development of a scintillation proximity assay for analysis of Na+/Cl- -dependent neurotransmitter transporter activity.

Human placental choriocarcinoma (JAR) cells endogenously expressing glycine transporter type 1a (GlyT1a) have been cultured in 96-well scintillating microplates to develop a homogenous screening assay for the detection of GlyT1 antagonists. In these microplates uptake of [14C]glycine was time dependent and saturable with a Michaelis-Menten constant (Km) of 27+/-3 microM. The GlyT1 transport inhibitors sarcosine, ALX-5407, and Org-24598 were tested and shown to block [14C]glycine uptake with expected IC50 values of 37.5+/-4.6 microM, 2.8+/-0.6 nM, and 6.9+/-0.9 nM, respectively. The [14C]glycine uptake process was sensitive to membrane Na+ gradient as blockade of membrane Na+/K+-ATPase by ouabain or Na+ exchanger by benzamil-disrupted glycine accumulation in JAR cells. Glycine influx was not affected by concentration of dimethyl sulfoxide up to 2%. The versatility of this technological approach was further confirmed by the characterization of a saturable [14C]taurine uptake in JAR cells. Taurine transport was of high affinity with a Km of 10.2+/-1.7 microM and fully inhibited by ALX-5407 (IC50=522 +/-83 nM). The developed assay is homogenous, rapid, versatile and amenable to automation for the discovery of new neurotransmitter transporter inhibitors.