Altered synaptic transmission at olfactory and vomeronasal nerve terminals in mice lacking N‐type calcium channel Cav2.2. (5th September 2014)

• Record Type: Journal Article
• Authors: Weiss, Jan; Pyrski, Martina; Weissgerber, Petra; Zufall, Frank
• Is Part Of: European journal of neuroscience. Volume 40:Number 10(2014:Nov.)
• Page Start: 3422
• Page End: 3435
• Publication Date: 2014-09-05
• Subjects: Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.12713
• Languages: English
• ISSNs: 0953-816X

Abstract

<abstract abstract-type="main" id="ejn12713-abs-0001"> <title>Abstract</title> <p>We investigated the role of voltage‐activated calcium (Cav) channels for synaptic transmission at mouse olfactory and vomeronasal nerve terminals at the first synapse of the main and accessory olfactory pathways, respectively. We provided evidence for a central role of the N‐type Cav channel subunit Cav2.2 in presynaptic transmitter release at these synapses. Striking Cav2.2 immunoreactivity was localised to the glomerular neuropil of the main olfactory bulb (MOB) and accessory olfactory bulb (AOB), and co‐localised with presynaptic molecules such as bassoon. Voltage‐clamp recordings of sensory nerve‐evoked, excitatory postsynaptic currents (EPSCs) in mitral/tufted (M/T) and superficial tufted cells of the MOB and mitral cells of the AOB, in combination with established subtype‐specific Cav channel toxins, indicated a predominant role of N‐type channels in transmitter release at these synapses, whereas L‐type, P/Q‐type, and R‐type channels had either no or only relatively minor contributions. In <italic>Cacna1b</italic> mutant mice lacking the Cav2.2 (α1B) subunit of N‐type channels, olfactory nerve‐evoked M/T cell EPSCs were not reduced but became blocker‐resistant, thus indicating a major reorganisation and compensation of Cav channel subunits as a result of the Cav2.2 deletion at this synapse. Cav2.2‐deficient mice also revealed that Cav2.2 was critically required for paired‐pulse depression of olfactory nerve‐evoked EPSCs in M/T cells of the MOB, and they demonstrated an essential requirement for Cav2.2 in vomeronasal nerve‐evoked EPSCs of AOB mitral cells. Thus, <italic>Cacna1b</italic> loss‐of‐function mutations are unlikely to cause general anosmia but <italic>Cacna1b</italic> emerges as a strong candidate in the search for mutations causing altered olfactory perception, such as changes in general olfactory sensitivity and altered social responses to chemostimuli.</p> </abstract>