Potentiation of analgesic efficacy but not side effects: co-administration of an α4β2 neuronal nicotinic acetylcholine receptor agonist and its positive allosteric modulator in experimental models of pain in rats.

Positive modulation of the neuronal nicotinic acetylcholine receptor (nAChR) α4β2 subtype by selective positive allosteric modulator NS-9283 has shown to potentiate the nAChR agonist ABT-594-induced anti-allodynic activity in preclinical neuropathic pain. To determine whether this benefit can be extended beyond neuropathic pain, the present study examined the analgesic activity and adverse effect profile of co-administered NS-9283 and ABT-594 in a variety of preclinical models in rats. The effect of the combined therapy on drug-induced brain activities was also determined using pharmacological magnetic resonance imaging.

Synthesis, potency, and in vivo profiles of quinoline containing histamine H3 receptor inverse agonists.

A new structural series of histamine H3 receptor antagonist was developed. The new compounds are based on a quinoline core, appended with a required basic aminoethyl moiety, and with potency- and property-modulating heterocyclic substituents. The analogs have nanomolar and subnanomolar potency for the rat and human H3R in various in vitro assays, including radioligand competition binding as well as functional tests of H3 receptor-mediated calcium mobilization and GTPgammaS binding.

Novel heterocyclic-substituted benzofuran histamine H3 receptor antagonists: in vitro properties, drug-likeness, and behavioral activity.

Three novel heterocyclic benzofurans A-688057 (1), A-687136 (2), and A-698418 (3) were profiled for their in vitro and in vivo properties as a new series of histamine H(3) receptor antagonists. The compounds were all found to have nanomolar potency in vitro at histamine H(3) receptors, and when profiled in vivo for CNS activity, all were found active in an animal behavioral model of attention. The compound with the most benign profile versus CNS side effects was selected for greater scrutiny of its in vitro properties and overall drug-likeness.

Evidence for tolerance following repeated dosing in rats with ciproxifan, but not with A-304121.

Blockade of presynaptic histamine H(3) receptors with potent and selective ligands improves cognitive function in rodents and there is significant interest in developing such drugs for long-term symptomatic treatment of CNS disorders such as attention deficit hyperactivity disorder (ADHD). Unfortunately, little is known about the effects of repeated exposure to H(3) receptor antagonists/inverse agonists. We therefore investigated the effects of acute and repeated daily administration of two potent, brain penetrating H(3) receptor antagonists/inverse agonists, ciproxifan and A-304121, on rat body weight, food and water intake, core temperature and locomotor activity, as well as H(3) receptor density and gene expression levels.

A-412997, a selective dopamine D4 agonist, improves cognitive performance in rats.

The recent development of a highly selective dopamine D4 receptor agonist, A-412997 (2-(3',4',5',6'-tetrahydro-2'H-[2,4'] bipyridinyl-1'-yl)-N-m-tolyl-acetamide), has provided a pharmacological tool with which to conduct systematic investigations into the putative role for dopamine D4 receptors in the central nervous system. These present studies evaluated the potential cognitive enhancing properties of A-412997 in rat models of ADHD (5-trial repeated acquisition inhibitory avoidance in Spontaneous Hypertensive Rat pups) and short-term memory (Social Recognition), in comparison with the less selective dopamine D4 receptor agonists PD168077 and CP226269. A-412997 showed significant dose-dependent efficacy in both models.