High-Throughput Screening of Neuronal Cl- Channels: Why and How?

Modulation of Glycine-Mediated Spinal Neurotransmission for the Treatment of Chronic Pain

Chronic pain constitutes a significant and expanding worldwide health crisis. Currently available analgesics poorly serve individuals suffering from chronic pain, and new therapeutic agents that are more effective, safer, and devoid of abuse liabilities are desperately needed. Among the myriad of cellular and molecular processes contributing to chronic pain, spinal disinhibition of pain signaling to higher cortical centers plays a critical role. Accumulating evidence shows that glycinergic inhibitory neurotransmission in the spinal cord dorsal horn gates nociceptive signaling, is essential in maintaining physiological pain sensitivity, and is diminished in pathological pain states. Thus, it is hypothesized that agents capable of enhancing glycinergic tone within the dorsal horn could obtund nociceptor signaling to the brain and serve as analgesics for persistent pain. This Perspective highlights the potential that pharmacotherapies capable of increasing inhibitory spinal glycinergic neurotransmission hold in providing new and transformative analgesic therapies for the treatment of chronic pain.

Optimizing the Expression of Recombinant αβγ GABAA Receptors in HEK293 Cells for High-Throughput Screening

Despite being important clinical targets, it is not straightforward to reliably express recombinant trimeric αβγ GABA-A receptors (GABAARs) for high-throughput screening. This study therefore sought to devise a simple and reliable means of transiently expressing α1β1γ1 and α1β1γ2 GABAARs in HEK293 cells. Expression efficiencies resulting from 5 different transfection strategies were assessed by flow cytometry and pharmacological analysis using an anion-sensitive yellow fluorescent protein-based assay. PolyFect™ and Effectene™, employed according to the manufacturers' instructions, conferred the strongest and most reliable expression of trimeric αβγ GABAARs. Functional analysis via the yellow fluorescent protein assay revealed dramatic differences in the pharmacological properties of γ1- and γ2-containing receptors, consistent with previous electrophysiological characterizations. The authors conclude that this method of expressing and screening recombinant GABAARs provides an effective means of discovering novel GABAAR modulators for use as therapeutic lead compounds and pharmacological probes. ( Journal of Biomolecular Screening 2009:86-91)