ABSTRACT
There remains an insufficient number of P2X7 receptor antagonists with adequate rodent potency, CNS permeability, and pharmacokinetic properties from which to evaluate CNS disease hypotheses preclinically. Herein, we describe the molecular pharmacology, safety, pharmacokinetics, and functional CNS target engagement of Lu AF27139, a novel rodent-active and CNS-penetrant P2X7 receptor antagonist. Lu AF27139 is highly selective and potent against rat, mouse, and human forms of the receptors. The rat pharmacokinetic profile is favorable with high oral bioavailability, modest clearance (0.79 L/(h kg)), and good CNS permeability. In vivo mouse CNS microdialysis studies of lipopolysaccharide (LPS)-primed and 2'(3')-O-(benzoylbenzoyl)adenosine-5'-triphosphate (BzATP)-induced IL-1ß release demonstrate functional CNS target engagement. Importantly, Lu AF27139 was without effect in standard in vitro and in vivo toxicity studies. Based on these properties, we believe Lu AF27139 will be a valuable tool for probing the role of the P2X7 receptor in rodent models of CNS diseases.
Subject(s)
Central Nervous System/metabolism , Purinergic P2X Receptor Antagonists/chemical synthesis , Receptors, Purinergic P2X7/metabolism , Adenosine Triphosphate/analogs & derivatives , Adenosine Triphosphate/pharmacology , Animals , Cell Line , Central Nervous System/drug effects , Dogs , Female , Half-Life , Humans , Interleukin-1beta/metabolism , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred C57BL , Microglia/cytology , Microglia/drug effects , Microglia/metabolism , Microsomes, Liver/metabolism , Monocytes/cytology , Monocytes/drug effects , Monocytes/metabolism , Purinergic P2X Receptor Antagonists/metabolism , Purinergic P2X Receptor Antagonists/pharmacology , Rats , Rats, Sprague-Dawley , Receptors, Purinergic P2X7/chemistryABSTRACT
Neuropathic pain is a debilitating, chronic condition with a significant unmet need for effective treatment options. Recent studies have demonstrated that in addition to neurons, non-neuronal cells such as microglia contribute to the initiation and maintenance of allodynia in rodent models of neuropathic pain. The Ca2+- activated K+ channel, KCa3.1 is critical for the activation of immune cells, including the CNS-resident microglia. In order to evaluate the role of KCa3.1 in the maintenance of mechanical allodynia following peripheral nerve injury, we used senicapoc, a stable and highly potent KCa3.1 inhibitor. In primary cultured microglia, senicapoc inhibited microglial nitric oxide and IL-1ß release. In vivo, senicapoc showed high CNS penetrance and when administered to rats with peripheral nerve injury, it significantly reversed tactile allodynia similar to the standard of care, gabapentin. In contrast to gabapentin, senicapoc achieved efficacy without any overt impact on locomotor activity. Together, the data demonstrate that the KCa3.1 inhibitor senicapoc is effective at reducing mechanical hypersensitivity in a rodent model of peripheral nerve injury.
Subject(s)
Acetamides/pharmacology , Hyperalgesia/complications , Hyperalgesia/drug therapy , Intermediate-Conductance Calcium-Activated Potassium Channels/antagonists & inhibitors , Peripheral Nerve Injuries/complications , Potassium Channel Blockers/pharmacology , Trityl Compounds/pharmacology , Acetamides/adverse effects , Acetamides/pharmacokinetics , Acetamides/therapeutic use , Animals , CHO Cells , Cricetinae , Cricetulus , Dose-Response Relationship, Drug , Drug Stability , Humans , Hyperalgesia/metabolism , Hyperalgesia/physiopathology , Locomotion/drug effects , Microglia/drug effects , Microglia/metabolism , Potassium/metabolism , Potassium Channel Blockers/adverse effects , Potassium Channel Blockers/pharmacokinetics , Potassium Channel Blockers/therapeutic use , Rats , Trityl Compounds/adverse effects , Trityl Compounds/pharmacokinetics , Trityl Compounds/therapeutic useABSTRACT
The identification of the novel and selective GPR3 inverse agonist AF64394, the first small molecule inhibitor of GPR3 receptor function, is described. Structure activity relationships and syntheses based around AF64394 are reported.