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J Neurosci

Title:		Calcium-activated sustained firing responses distinguish accessory from main olfactory bulb mitral cells
Author(s):		Shpak G; Zylbertal A; Yarom Y; Wagner S;
Address:		"Department for Neurobiology and Ethology and Center for Gene Manipulation in the Brain, University of Haifa, Haifa 31905, Israel"
Journal Title:		J Neurosci
Year:		2012
Volume:		32
Issue:		18
Page Number:		6251 - 6262
DOI:		10.1523/JNEUROSCI.4397-11.2012
ISSN/ISBN:		1529-2401 (Electronic) 0270-6474 (Print) 0270-6474 (Linking)
Abstract:		"Many mammals rely on pheromones for mediating social interactions. Recent studies indicate that both the main olfactory system (MOS) and accessory olfactory system (AOS) detect and process pheromonal stimuli, yet the functional difference between these two chemosensory systems remains unclear. We hypothesized that the main functional distinction between the MOS and AOS is the type of sensory information processing performed by each system. Here we compared the electrophysiological responses of mitral cells recorded from the accessory olfactory bulb (AOB) and main olfactory bulb (MOB) in acute mouse brain slices to various stimuli and found them markedly different. The response of MOB mitral cells to brief (0.1 ms, 1-100 V) stimulation of their sensory afferents remained transient regardless of stimulus strength, whereas sufficiently strong stimuli evoked sustained firing in AOB mitral cells lasting up to several minutes. Using EPSC-like current injections (10-100 pA, 10 ms rise time constant, 5 s decay time constant) in the presence of various synaptic blockers (picrotoxin, CGP55845, APV, DNQX, E4CPG, and MSPG), we demonstrated that this difference is attributable to distinct intrinsic properties of the two neuronal populations. The AOB sustained responses were found to be mediated by calcium-activated nonselective cationic current induced by transient intense firing. This current was found to be at least partially mediated by TRPM4 channels activated by calcium influx. We hypothesize that the sustained activity of the AOS induces a new sensory state in the animal, reflecting its social context"
Keywords:		"Action Potentials/*physiology Animals Calcium/*metabolism Calcium Signaling/*physiology Male Mice Mice, Inbred C57BL Olfactory Bulb/*physiology Smell/*physiology;"
Notes:		"MedlineShpak, Guy Zylbertal, Asaph Yarom, Yosef Wagner, Shlomo eng Research Support, Non-U.S. Gov't 2012/05/04 J Neurosci. 2012 May 2; 32(18):6251-62. doi: 10.1523/JNEUROSCI.4397-11.2012"