Pharmacology of the β-carboline FG-7142, a partial inverse agonist at the benzodiazepine allosteric site of the GABAA receptor:: Neurochemical, neurophysiological, and behavioral effects

Given the well-established role of benzodiazepines in treating anxiety disorders, beta-carbolines, spanning a spectrum from full agonists to full inverse agonists at the benzodiazepine allosteric site for the GABA(A) receptor, can provide valuable insight into the neural mechanisms underlying anxiety-related physiology and behavior. FG-7142 is a partial inverse agonist at the benzodiazepine allosteric site with its highest affinity for the alpha 1 subunit-containing GABA(A) receptor, although it is not selective. FG-7142 also has its highest efficacy for modulation of GABA-induced chloride flux mediated at the a1 subunit-containing GABA(A) receptor. FG-7142 activates a recognized anxiety-related neural network and interacts with serotonergic, dopaminergic, cholinergic, and noradrenergic modulatory systems within that network. FG-7142 has been shown to induce anxietyrelated behavioral and physiological responses in a variety of experimental paradigms across numerous mammalian and non-mammalian species, including humans. FG-7142 has proconflict actions across anxiety-related behavioral paradigms, modulates attentional processes, and increases cardioacceleratory sympathetic reactivity and neuroendocrine reactivity. Both acute and chronic FG-7142 treatment are proconvulsive, upregulate cortical adrenoreceptors, decrease subsequent actions of GABA and beta-carboline agonists, and increase the effectiveness of subsequent GABA(A) receptor antagonists and beta-carboline inverse