Does the Environmental Air Impact the Condition of the Vomeronasal Organ? A Mouse Model for Intensive Farming

Abstract

Chemical communication in mammals is ensured by exchanging chemical signals through the vomeronasal organ (VNO) and its ability to detect pheromones. The alteration of this organ has been proven to impact animal life, participating in the onset of aggressive behaviors in social groups. To date, few studies have highlighted the possible causes leading to these alterations, and the farming environment has not been investigated, even though irritant substances such as ammonia are known to induce serious damage in the respiratory tract. The goal of this study was to investigate the environmental impact on the VNO structure. Thirty mice were split into three groups, one housed in normal laboratory conditions and the other two in confined environments, with or without the release of litter ammonia. VNOs were analyzed using histology and immunohistochemistry to evaluate the effect of different environments on their condition. Both restricted conditions induced VNO alterations (p = 0.0311), soft-tissue alteration (p = 0.0480), and nonsensory epithelium inflammation (p = 0.0024). There was glycogen accumulation (p < 0.0001), the olfactory marker protein was underexpressed (p < 0.0001), and Gαi2 positivity remained unchanged while Gαo expression was upregulated in confined conditions. VNO conditions seemed to worsen with ammonia, even if not always significantly. These murine model results suggest that the housing environment can strongly impact VNO conditions, providing novel insights for improving indoor farming systems.

Pheromone Sensing in Mammals: A Review of the Vomeronasal System

“…This has been bolstered by the optimization of an MRI protocol for in vivo visualization of the VNO [371], and the recent identification of a case of canine vomeronasal agenesis, which manifested significant behavioral disorders, such as an inability for sexual discrimination of conspecifics and reduced sexual behavior [372]. Moreover, the use of pheromonotherapy, like the application of dog-appeasing pheromone (DAP) to mitigate symptoms of separation anxiety, including house soiling, vocalizations, and damage [373,374], along with a deepening in the links between VNO inflammation and aggressive behaviors in canids, felids, and livestock [375][376][377][378], has further developed this interest in the dog VNS.…”

Pheromone Sensing in Mammals: A Review on the Vomeronasal System

“…This has been bolstered by the optimization of an MRI protocol for in vivo visualization of the VNO [342], and the recent identification of a case of canine vomeronasal agenesis, which manifested significant behavioral disorders, such as an inability for sexual discrimination of conspecifics and reduced sexual behavior [343]. Moreover, the use of pheromonotherapy, like the application of dog appeasing pheromone (DAP) to mitigate symptoms of separation anxiety, including house soiling, vocalizations, and damage [344,345], along with the deepening in the links between VNO inflammation and aggressive behaviors in canids, felids, and livestock [346][347][348][349], has further developed this interest in the dog VNS. Within the carnivores, the Mustelidae family has been the subject of extensive study, as the characterization of its AOB remains unresolved.…”