Mutual influences between the main olfactory and vomeronasal systems in development and evolution

Abstract

The sense of smell plays a crucial role in the sensory world of animals. Two chemosensory systems have been traditionally thought to play-independent roles in mammalian olfaction. According to this, the main olfactory system (MOS) specializes in the detection of environmental odorants, while the vomeronasal system (VNS) senses pheromones and semiochemicals produced by individuals of the same or different species. Although both systems differ in their anatomy and function, recent evidence suggests they act synergistically in the perception of scents. These interactions include similar responses to some ligands, overlap of telencephalic connections and mutual influences in the regulation of olfactory-guided behavior. In the present work, we propose the idea that the relationships between systems observed at the organismic level result from a constant interaction during development and reflects a common history of ecological adaptations in evolution. We review the literature to illustrate examples of developmental and evolutionary processes that evidence these interactions and propose that future research integrating both systems may shed new light on the mechanisms of olfaction.

Nrp2 is sufficient to instruct circuit formation of mitral-cells to mediate odour-induced attractive social responses

“…MCs send their axons to various brain regions by following the lateral olfactory tract641424344 (Fig. 4a, right).…”

Trpc2 pseudogenization dynamics in bats reveal ancestral vomeronasal signaling, then pervasive loss

“…Instead of an increase or expansion in the main olfactory system correlated with vomeronasal loss (a hypothesis rejected by Hayden et al 2014), olfaction and vomerolfaction could be redundant, allowing selective pressures on vomerolfaction to relax in some species. Recent neurobiological, developmental, and behavioral studies suggest there is more interaction between the two nasal chemosensory systems than previously thought (Suárez et al 2012;Baum and Cherry 2014;Omura and Mombaerts 2014;Ma 2015). In mice, for example, some pheromone receptors may also be present in the main olfactory epithelium (Omura and Mombaerts 2014;Kanageswaran et al 2015), possibly explaining why some apparently pheromone-mediated behavior is maintained in species lacking the vomeronasal organ.…”

Convergent vomeronasal system reduction in mammals coincides with convergent losses of calcium signalling and odorant‐degrading genes

“…Most mammals possess two olfactory systems: the main olfactory system and the vomeronasal system which synergistically mediate the sense of smell (Kelliher, ; Suarez, Garcia‐Gonzalez, & Castro, ). The main olfactory system detects odorants through the olfactory epithelium and processes their detection in the main olfactory bulb, whereas the vomeronasal system (VNS) forms an accessory olfactory pathway with distinct organs (Figure ).…”

“…In the VNO, primary sensory neurons are activated by nonvolatile or ephemeral chemical cues and send signals to the accessory olfactory bulb (Dulac, ; Stowers & Marton, ). Although there are clear indications that the main olfactory system and VNS are functionally intertwined (Kelliher, ; Stowers & Marton, ; Suarez et al, ), activity patterns in the neural vomeronasal pathway, ablation of the VNO and arguably knockout studies suggest that the mammalian VNS is of special importance for sensing chemical cues that affect social and sexual behaviours such as the detection of mating partners, parental care and territorial aggression (Bean & Wysocki, ; Stowers, Holy, Meister, Dulac, & Koentges, ; Tachikawa, Yoshihara, & Kuroda, ; Yu, ).…”