Benzodiazepines remain widely used for the treatment of anxiety disorders despite prominent, often limiting side effects including sedation, muscle relaxation, and ataxia. A compound producing a robust anxiolytic action comparable to benzodiazepines, but lacking these limiting side effects at therapeutic doses (an anxioselective agent), would represent an important advance in the treatment of generalized anxiety disorder, and perhaps other anxiety disorders. Here we report that the pyrazolo[1,5-a]-pyrimidine, ocinaplon, exhibits an anxioselective profile in both preclinical procedures and in patients with generalized anxiety disorder, the most common of the anxiety disorders. In rats, ocinaplon produces significant muscle relaxation, ataxia, and sedation only at doses >25-fold higher than the minimum effective dose (3.1 mg͞kg) in the Vogel ''conflict'' test. This anticonflict effect is blocked by flumazenil (Ro 15-1788), indicating that like benzodiazepines, ocinaplon produces an anxiolytic action through allosteric modulation of GABA A receptors. Nonetheless, in eight recombinant GABAA receptor isoforms expressed in Xenopus oocytes, the potency and efficacy of ocinaplon to potentiate GABA responses varied with subunit composition not only in an absolute sense, but also relative to the prototypical benzodiazepine, diazepam. In a double blind, placebo controlled clinical trial, a 2-week regimen of ocinaplon (total daily dose of 180 -240 mg) produced statistically significant reductions in the Hamilton rating scale for anxiety scores. In this study, the incidence of benzodiazepine-like side effects (e.g., sedation, dizziness) in ocinaplon-treated patients did not differ from placebo. These findings indicate that ocinaplon represents a unique approach both for the treatment and understanding of anxiety disorders.generalized anxiety disorder ͉ benzodiazepines

Different mitochondrial nitric-oxide synthase (mt-NOS) isoforms have been described in rat and mouse tissues, such as liver, thymus, skeletal muscle, and more recently, heart and brain. The modulation of these variants by thyroid status, hypoxia, or gene deficiency opens a broad spectrum of mtNOS-dependent tissuespecific functions. In this study, a new NOS variant is described in rat brain with an M r of 144 kDa and mainly localized in the inner mitochondrial membrane. During rat brain maturation, the expression and activity of mt-NOS were maximal at the late embryonic stages and early postnatal days followed by a decreased expression in the adult stage (100 ؎ 9 versus 19 ؎ 2 pmol of [ 3 H]citrulline/min/mg of protein, respectively). This temporal pattern was opposite to that of the cytosolic 157-kDa nNOS protein. Mitochondrial redox changes followed the variations in mtNOS activity: mtNOSdependent production of hydrogen peroxide was maximal in newborns and decreased markedly in the adult stage, thus reflecting the production and utilization of mitochondrial matrix nitric oxide. Moreover, the activity of brain Mn-superoxide dismutase followed a developmental pattern similar to that of mtNOS. Cerebellar granular cells isolated from newborn rats and with high mtNOS activity exhibited maximal proliferation rates, which were decreased by modifying the levels of either hydrogen peroxide or nitric oxide. Altogether, these findings support the notion that a coordinated modulation of mtNOS and Mn-superoxide dismutase contributes to establish the rat brain redox status and participate in the normal physiology of brain development.

The regulated expression of type A ␥-aminobutyric acid (GABA) receptor (GABA A R) subunit genes plays a critical role in neuronal maturation and synaptogenesis. It is also associated with a variety of neurological diseases. Changes in GABA A receptor ␣1 subunit gene (GABRA1) expression have been reported in animal models of epilepsy, alcohol abuse, withdrawal, and stress. Understanding the genetic mechanism behind such changes in ␣ subunit expression will lead to a better understanding of the role that signal transduction plays in control over GABA A R function and brings with it the promise of providing new therapeutic tools for the prevention or cure of a variety of neurological disorders. Here we show that activation of protein kinase C increases ␣1 subunit levels via phosphorylation of CREB (pCREB) that is bound to the GABRA1 promoter (GABRA1p). In contrast, activation of protein kinase A decreases levels of ␣1 even in the presence of pCREB. Decrease of ␣1 is dependent upon the inducible cAMP early repressor (ICER) as directly demonstrated by ICER-induced down-regulation of endogenous ␣1-containing GABA A Rs at the cell surface of cortical neurons. Taken together with the fact that there are less ␣1␥2-containing GABA A Rs in neurons after protein kinase A stimulation and that activation of endogenous dopamine receptors down-regulates ␣1 subunit mRNA levels subsequent to induction of ICER, our studies identify a transcriptional mechanism for regulating the cell surface expression of ␣1-containing GABA A Rs that is dependent upon the formation of CREB heterodimers. ␥-Aminobutyric acid (GABA)4 type A receptors (GABA A Rs) are ligand-gated chloride ion channels that mediate the majority of fast synaptic inhibition in the mammalian brain (1). They are pentameric in structure and are composed of multiple subunit isoforms coming from eight distinct classes: ␣, ␤, ␥, ␦, , ⑀, , and . Diversity in receptor subtypes is controlled by the regulated expression of 19 different subunit genes and the alternative splicing of individual subunit transcripts (2-4). Most importantly, differential receptor subunit composition produces functionally and pharmacologically distinct GABA A Rs at certain times during development and in certain regions of the brain (5-8).The transcription of different GABA A R subunit genes (GABRs) is likely to involve a complex system of regulatory controls that remain to be identified. Several lines of evidence suggest that ␣1 subunit expression is activity-dependent (9 -11). Treatment with N-methyl-D-aspartate, a selective activator of an important class of excitatory ligand-gated ion channels, stimulates ␣1 subunit expression in cultured cerebellar granule cells (12, 13). In contrast, chronic treatment of cortical neurons with GABA decreases levels of GABA A R ␣1 subunit mRNAs (14 -16), which is dependent on voltage-gated calcium channel activity and most likely an alteration in transcription (15). In addition, prolonged benzodiazepine (BZ) treatment decreases ␣1 mRNA levels in the rat hippocampal CA...

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