sb-222200 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