A novel GABA(A) alpha 5 receptor inhibitor with therapeutic potential.

Novel 2,3-benzodiazepine and related isoquinoline derivatives, substituted at position 1 with a 2-benzothiophenyl moiety, were synthesized to produce compounds that potently inhibited the action of GABA on heterologously expressed GABAA receptors containing the alpha 5 subunit (GABAA α5), with no apparent affinity for the benzodiazepine site. Substitutions of the benzothiophene moiety at position 4 led to compounds with drug-like properties that were putative inhibitors of extra-synaptic GABAA α5 receptors and had substantial blood-brain barrier permeability. Initial characterization in vivo showed that 8-methyl-5-[4-(trifluoromethyl)-1-benzothiophen-2-yl]-1,9-dihydro-2H-[1,3]oxazolo[4,5-h][2,3]benzodiazepin-2-one was devoid of sedative, pro-convulsive or motor side-effects, and enhanced the performance of rats in the object recognition test.

P2X7 receptor mediated phosphorylation of p38MAP kinase in the hippocampus.

This study was designed to explore the effect of P2X7 receptor (P2X7R) activation on the expression of p38 MAP kinase (p38 MAPK) enzyme in hippocampal slices of wild-type (WT) and P2X7R(-/-) mice using the Western blot technique and to clarify its role in P2X7 receptor mediated [(3)H]glutamate release. ATP (1 mM) and the P2X7R agonist BzATP (100 microM) significantly increased p38 MAPK phosphorylation in WT mice, and these effects were absent in the hippocampal slices of P2X7R(-/-) mice. Both ATP- and BzATP-induced p38 MAPK phosphorylations were sensitive to the p38 MAP kinase inhibitor, SB203580 (1 microM).

Lack of ATP-evoked GABA and glutamate release in the hippocampus of P2X7 receptor-/- mice.

In this study we revealed the participation of P2X(7) receptors in the modulation of electrical stimulation and ATP-evoked GABA and glutamate release from mouse hippocampal slices. Whereas the uptake of radioactivity was not changed, the electrical stimulation-induced release of both [(3)H]glutamate and [(3)H]GABA was decreased in the hippocampus of P2X(7) receptor-deficient mice. ATP (10 mM) elicited [(3)H]glutamate and [(3)H]GABA efflux in wild-type mice, which was inhibited by the non-selective P2 receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid tetrasodium (30 microM) and the P2X(7)-selective antagonist Brilliant Blue G (1 microM).

P2X receptor activation elicits transporter-mediated noradrenaline release from rat hippocampal slices.

This study was designed to test the hypothesis of whether activation of presynaptic P2X receptor-gated ion channels elicits noradrenaline release from central catecholaminergic terminals. ATP, alpha,beta-methylene-adenosine 5'-triphosphate (alpha,beta-methyleneATP), and ADP elicited concentration-dependent [3H]noradrenaline outflow from superfused rat hippocampal slices with the following rank order of agonist potency: alpha,beta-methyleneATP > ATP > ADP. Among P2 receptor antagonists, pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (30 microM), 4,4',4",4"'-[carbonylbis(imino-5,1,3-benzenetriyl-bis(carbonylimino))]tetrakis-1,3-benzenedisulfonic acid (100 nM), and 8,8'-[carbonybis(imino-3,1-phenylenecarbonylimino)]bis1,3,5-naphthalenetrisulphonic acid (10 microM) significantly inhibited the outflow of [3H]noradrenaline, evoked by ATP, whereas Brilliant Blue G (100 nM), 2'-deoxy-N6-methyladenosine 3',5'-bisphosphate tetraammonium (10 microM), the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (250 nM), and the A2A receptor antagonist 3,7-dimethyl-1-propargylxanthine (250 nM) were ineffective.