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Vomeronasal Phenotype and Behavioral Alterations in Gαi2 Mutant Mice
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Molecular Biology.
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
2003 (English)In: Current Biology, ISSN 0960-9822, Vol. 13, no 14, 1214-1219 p.Article in journal (Refereed) Published
Abstract [en]

Several social and reproductive behaviors are under the influence of the vomeronasal (VN) organ; VN neurons detect odorous molecules emitted by individuals of the same species. There are two types of VN neurons, and these differ in their expression of chemosensory receptors and G protein subunits. The significance of this dichotomy is largely unknown. VN neurons express high levels of either G alpha i2 or G alpha o. A mouse line carrying a targeted disruption of the G alpha i2 gene offered the opportunity for studying the effects of a lack of receptor signaling through the heterotrimeric Gi2 protein in one VN cell type. As a consequence of this deficiency, the number of VN neurons that normally express G alpha i2 is decreased by half. These residual neurons are defective in eliciting a response in their target neurons in the accessory olfactory bulb. Moreover, G alpha i2 mutant mice show alterations in behaviors for which an intact VN organ is known to be important. Display of maternal aggressive behavior is severely blunted, and male mice show significantly less aggression toward an intruder. However, male mice show unaltered sexual-partner preference. This suggests that the two types of VN neurons may have separate functions in mediating behavioral changes in response to chemosensory information.

Place, publisher, year, edition, pages
2003. Vol. 13, no 14, 1214-1219 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:umu:diva-4157DOI: 10.1016/S0960-9822(03)00452-4PubMedID: 12867032OAI: diva2:143141
Available from: 2004-11-22 Created: 2004-11-22 Last updated: 2010-04-20Bibliographically approved
In thesis
1. Zonal organization of the mouse olfactory systems
Open this publication in new window or tab >>Zonal organization of the mouse olfactory systems
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Animals survey their environment for relevant odorous chemical compounds by means of the olfactory system. This system is in most vertebrates divided into a main and accessory olfactory system with two specialized neuroepithelia, the olfactory and the vomeronasal epithelium, respectively. The sensory neurons reside in these epithelia and together the neurons have an extraordinary sensitivity and are capable of detecting a vast number of different chemical molecules. After processing the chemical information, behavior may be altered. The information about a chemicals structure is deconstructed into a format that the brain may process. This is facilitated by organizing sensory neurons into a map and that the individual neuron responds only to one chemical feature. The sensory maps appear to have zones with different neuronal subpopulations. This thesis is addressing the fact that establishment, maintenance and function of these zones are unknown.

We identify a gene (NQO1) to be selectively expressed in defined zone of the olfactory and the vomeronasal epithelia, respectively. NQO1-positive and negative axons segregate within the olfactory nerve and maintain a zonal organization when reaching olfactory bulb target neurons. These results indicate that one zone of both the accessory and the main olfactory projection maps is composed of sensory neurons specialized in reducing environmental and/or endogenously produced quinones via an NQO1-dependent mechanism.

In addition, we have identified genes expressed in a graded manner that correlates with the dorsomedial-ventrolateral zonal organization of the olfactory epithelia. Considering the known functions of identified genes in establishment of cell specificity and precise axonal targeting, we suggest that zonal division of the primary olfactory systems is maintained, during continuous neurogenesis, as a consequence of topographic counter gradients of positional information.

The vomeronasal sensory neurons (VSN) are organized into an apical and a basal zone. The zones differ in expression of e.g. chemosensory receptor families and Gα protein subunits (Gαi2 and Gαo). We have analyzed transgenic mice (OMP-dnRAR) in which the VSNs are unresponsive to the function of one of the genes identified herein (RALDH2). The phenotype observed suggests that endogenous produced retinoic acid is selectively required for postnatal survival of neurons in the Gαo-positive zone. Analyses of another mouse line target deleted in the Gαi2 gene (Gαi2 mutant) reveal a cellular phenotype that is opposite to that of OMP-dnRAR mice. Consequently in these mice, the apical Gαi2-positive zone is reduced whereas VSNs in the basal zone are not affected.

Several social and reproductive behaviors are under the influence of the vomeronasal organ. We have analyzed some behavioral consequences of having deficient neurons that corresponds to either of the two zones. We propose that cues important for aggressive behavior are detected by apical vomeronasal zone, while cues detected by both apical and basal VSNs influence gender preference behavior.

Place, publisher, year, edition, pages
Umeå: Molekylärbiologi, 2004. 116 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 911
Molecular biology, olfactory, vomeronasal, gene expression, zone, organization, behavior, Molekylärbiologi
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
urn:nbn:se:umu:diva-336 (URN)91-7305-706-1 (ISBN)
Public defence
2004-10-01, Major Groove, 6L, Norrlands Universitetssjukhus, Umeå, 09:00 (English)
Available from: 2004-11-22 Created: 2004-11-22 Last updated: 2010-01-29Bibliographically approved

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Norlin, MarianneGussing, FredrikBerghard, Anna
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