The main and accessory olfactory systems of female mice are activated differentially by dominant versus subordinate male urinary odors - PubMed (original) (raw)

Comparative Study

The main and accessory olfactory systems of female mice are activated differentially by dominant versus subordinate male urinary odors

Alexandra Veyrac et al. Brain Res. 2011.

Abstract

Previous studies have shown that female preferences for male pheromones depend on the female's reproductive condition and the dominance status of the male. However, it is unknown which olfactory system detects the odors that result in a preference for a dominant male. Therefore, in the present study, we asked whether dominant versus subordinate male urinary odors differentially activate the main and accessory olfactory systems in female (C57Bl/6j) mice by monitoring the induction of the immediate early gene, c-fos. A more robust induction of Fos was observed in female mice which had direct nasal contact with dominant male urinary odors in four specific segments of the accessory olfactory system, i.e., the posteroventral part of the medial amygdala, the bed nucleus of the stria terminalis, the medial part of the preoptic nucleus and the ventrolateral part of the ventromedial hypothalamus, compared to females that were exposed to subordinate male urine. This greater activation of the accessory olfactory pathway by dominant male urine suggests that there are differences in the nonvolatile components of dominant versus subordinate male urine that are detected by the vomeronasal organ. By contrast, subordinate male urinary odors induced a greater activation in the piriform cortex which is part of the main olfactory system, suggesting that female mice discriminate between dominant and subordinate male urine using their main olfactory system as well.

Copyright © 2011 Elsevier B.V. All rights reserved.

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Figures

Figure 1

Figure 1

Drawings modified from the mouse brain atlas (Paxinos and Franklin, 2001) showing the location of forebrain regions in which Fos-immunoreactive cells were counted. The distance of each coronal brain slice rostral to the interaural line is given in parentheses for each panel. The counting areas are shown as a black rectangle. The two different sizes of rectangles correspond to the areas analyzed using either a 20x or 40x objective, respectively. A: Accessory olfactory bulb (AOB). B: Medial amygdaloid nucleus, postero-ventral (MePV) and postero-dorsal (MePD) parts. C: Medial part of the Anterior Bed Nucleus of the Stria Terminalis (BNST). D: Medial part of the Preoptic nucleus (MPN). E: Ventro lateral part of the Ventromedial hypothalamic nucleus (VMH-VL). F: Anterior part of the Piriform cortex. G: Posterior part of the Piriform cortex. H: Anterior cortical Amygdaloid nucleus (ACo). Additional abbreviations: MiA= accessory mitral cell layer; GlA= accessory glomerular layer; GrA= accessory granular layer; AOL= anteriolateral olfactory nucleus; 3V= third ventricle; BMA= basomedial amygdaloid nucleus; opt= optic tract; LV=lateral ventricle; f=fornix; aca= anterior commisure, anterior part ; CPu=caudate putamen; acp=anterior commisure, posterior part; HDB= horizontal limb diagonal band.

Figure 2

Figure 2

Fos expression in the accessory olfactory bulb. A: granular cell layer, anterior part of the AOB; B: mitral cell layer, anterior part of the AOB; C: granular cell layer, posterior part of the AOB, and D: mitral cell layer, posterior part of the AOB. Data are expressed as means ± SEM. *p<0.05 compared to water-exposed females; Water n=4; Dominant n=4-5 Subordinate n=3.

Figure 3

Figure 3

Fos expression in the accessory olfactory pathway. A: Posteroventral portion of the medial amygdala (MePV); B: posterodorsal portion of the medial amygdala (MePD); C: medial preoptic nucleus (MPN); D: ventrolateral portion of the ventromedial hypothalamus (VMH-VL); E: posteromedial portion of the bed nucleus of the stria terminalis (BNST-). Values are means ± SEM. *p<0.05 compared to water exposed females. S p<0.05: significantly different between dominant versus subordinate male urine exposed females; Water n=3-4; Dominant n=3-5; Subordinate n=3-4.

Figure 4

Figure 4

A: contour plots showing areas of main olfactory bulb (MOB) glomerular activation in females exposed to water (clean; n=4), dominant male urine (n=5), or subordinate male urine (n=4) The scale showing the number of activated glomeruli per bin, 10° radial angle is located to the right of each panel; B: Mann-Whitney U comparisons between clean vs dominant, clean vs subordinate, and dominant vs subordinate male urine. Significant p-values were determined using a false discovery rate (FDR) critical value of 0.025 (1E -1.6)

Figure 5

Figure 5

Fos expression in the main olfactory pathway. A: Anterior cortical medial amygdala (ACo); B: Piriform cortex; C: Anterior part of the piriform cortex; D: Posterior part part of the Piriform cortex. Values are means ± SEM. *p<0.05 compared to water (clean) exposed females. S p<0.05 compared to females exposed to dominant male urine; Water n=3-4; Dominant n=4-5; Subordinate n=3-4.

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