piperidines and 2-aminoethoxydiphenyl-borate

To understand the functions of the neocortex, it is essential to characterize the properties of neurons constituting cortical circuits. Here, we focused on a distinct group of GABAergic neurons that are defined by a specific colocalization of intense labeling for both neuronal nitric oxide synthase (nNOS) and substance P (SP) receptor [neurokinin 1 (NK1) receptors]. We investigated the mechanisms of the SP actions on these neurons in visual cortical slices obtained from young glutamate decarboxylase 67-green fluorescent protein knock-in mice. Bath application of SP induced a nonselective cation current leading to depolarization that was inhibited by the NK1 antagonists in nNOS-immunopositive neurons. Ruthenium red and La(3+), transient receptor potential (TRP) channel blockers, suppressed the SP-induced current. The SP-induced current was mediated by G proteins and suppressed by D609, an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), but not by inhibitors of phosphatidylinositol-specific PLC, adenylate cyclase or Src tyrosine kinases. Ca(2+) imaging experiments under voltage clamp showed that SP induced a rise in intracellular Ca(2+) that was abolished by removal of extracellular Ca(2+) but not by depletion of intracellular Ca(2+) stores. These results suggest that SP regulates nNOS neurons by activating TRP-like Ca(2+)-permeable nonselective cation channels through a PC-PLC-dependent signaling pathway.

Topics: Animals; Anthracenes; Boron Compounds; Calcium; Calcium Channel Blockers; Dose-Response Relationship, Drug; Electric Stimulation; Excitatory Amino Acid Agents; GABAergic Neurons; Glutamate Decarboxylase; Imidazoles; In Vitro Techniques; Isoindoles; Mice; Mice, Transgenic; Neurokinin-1 Receptor Antagonists; Nitric Oxide Synthase Type III; Patch-Clamp Techniques; Piperidines; Quinolines; Quinuclidines; Signal Transduction; Substance P; Type C Phospholipases; Visual Cortex

Brexpiprazole, a novel atypical antipsychotic drug, is currently being tested in clinical trials for treatment of psychiatric disorders, such as schizophrenia and major depressive disorder. The drug is known to act through a combination of partial agonistic activity at 5-hydroxytryptamine (5-HT)1A, and dopamine D2 receptors, and antagonistic activity at 5-HT2A receptors. Accumulating evidence suggests that antipsychotic drugs act by promoting neurite outgrowth. In this study, we examined whether brexpiprazole affected neurite outgrowth in cell culture. We found that brexpiprazole significantly potentiated nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells, in a concentration dependent manner. The selective 5-HT1A receptor antagonist, WAY-100,635, was able to block the effects of brexpiprazole on neurite outgrowth, unlike the selective dopamine D2 receptor antagonist, raclopride. Furthermore, the selective 5-HT2A receptor antagonist M100907, but not DOI (5-HT2A receptor agonist), significantly potentiated NGF-induced neurite outgrowth. Moreover, xestospongin C and 2-aminoethoxydiphenyl borate (2-APB), both specific inhibitors of inositol 1,4,5-triphosphate (IP3) receptors, significantly blocked the effects of brexpiprazole. These findings suggest that brexpiprazole-induced neurite outgrowth is mediated through 5-HT1A and 5-HT2A receptors, and subsequent Ca(2+) signaling via IP3 receptors.

Topics: Animals; Aripiprazole; Boron Compounds; Dose-Response Relationship, Drug; Drug Synergism; Fluorobenzenes; HSP90 Heat-Shock Proteins; Inositol 1,4,5-Trisphosphate Receptors; Macrocyclic Compounds; Nerve Growth Factor; Neurites; Oxazoles; PC12 Cells; Piperazines; Piperidines; Pyridines; Quinolones; Rats; Receptor, Serotonin, 5-HT1A; Receptor, Serotonin, 5-HT2A; Serotonin Agents; Thiophenes

Endothelins are known to be among the most potent endogenous vasoconstrictors. Vasoconstriction of the spiral modiolar artery, which supplies the cochlea, may be implicated in hearing loss and tinnitus. The purpose of the present study was to determine whether the spiral modiolar artery responds to endothelin, whether a change in the cytosolic Ca2+ concentration ([Ca2+]i) mediates the response and which endothelin receptors are present. The vascular diameter and [Ca2+]i were measured simultaneously by videomicroscopy and microfluorometry in the isolated spiral modiolar artery from the gerbil. ET-1 induced a transient [Ca2+]i increase and a strong and long-lasting vasoconstriction. The transient [Ca2+]i increase underwent rapid desensitization, was independent of extracellular Ca2+ and inhibited by the IP3-receptor blocker (75 microm) 2-aminoethoxydiphenyl borate (2-APB) and by depletion of Ca2+ stores with 10(-6) m thapsigargin. In contrast, the vasoconstriction displayed no comparable desensitization. The initial vasoconstriction was independent of extracellular Ca2+ but maintenance of the constriction depended on the presence of extracellular Ca2+. The half-maximal concentration values (EC50) for the agonists ET-1, ET-3 and sarafotoxin S6c were 0.8 nm, >10 nm and >100 nm, respectively. Affinity constants for the antagonists BQ-123 and BQ-788 were 24 nm and 77 nm, respectively. These observations demonstrate that ET-1 mediates a vasoconstriction of the gerbil spiral modiolar artery via ETA receptors and an IP3 receptor-mediated release of Ca2+ from thapsigargin-sensitive Ca2+ stores. The marked difference in desensitization between Ca2+ mobilization and vasoconstriction suggests that Ca2+ mobilization is not solely responsible for the vasoconstriction and that other signaling mechanisms must be present.

Topics: Animals; Antihypertensive Agents; Arteries; Boron Compounds; Calcium; Calcium Signaling; Cochlea; Cytophotometry; Endothelin Receptor Antagonists; Endothelin-1; Enzyme Inhibitors; Gerbillinae; Microscopy, Video; Oligopeptides; Peptides, Cyclic; Piperidines; Receptor, Endothelin A; Receptors, Endothelin; Thapsigargin; Vasoconstriction; Vasoconstrictor Agents; Viper Venoms