Histological and Immunohistochemical Characterization of Vomeronasal Organ Aging in Mice

Abstract

The vomeronasal organ (VNO) plays a crucial role in animal behavior since it is responsible for semiochemical detection and, thus, for intra- and interspecific chemical communication, through the vomeronasal sensory epithelium (VNSE), composed of bipolar sensory neurons. This study aimed to explore a well-recognized cause of neuronal degeneration, only rarely explored in this organ: aging. Murine VNOs were evaluated according to 3 age groups (3, 10, and 24 months) by histology to assess VNSE changes such as cellular degeneration or glycogen accumulation and by immunohistochemistry to explore nervous configuration, proliferation capability, and apoptosis with the expression of olfactory marker protein (OMP), Gαi2, Gαo, Ki-67, and cleaved caspase-3 proteins. These markers were quantified as percentages of positive signal in the VNSE and statistical analyses were performed. Cellular degeneration increased with age (p < 0.0001) as well as glycogen accumulation (p < 0.0001), Gαo expression (p < 0.0001), and the number of cleaved-caspase3 positive cells (p = 0.0425), while OMP and Gαi2 expressions decreased with age (p = 0.0436 and p < 0.0001, respectively). Ki67-positive cells were reduced, even if this difference was not statistically significant (p = 0.9105). Due to the crucial role of VNO in animal life, this study opens the door to interesting perspectives about chemical communication efficiency in aging animals.

Natural and pathological aging distinctively impact the vomeronasal detection system and social behavior

“…1 ). Our findings are consistent with two previous studies (Brann and Firestein, 2010, Mechin et al, 2021), which reported an overall thinning of the vomeronasal sensory epithelium (Mechin et al, 2021) and reduced VSE neurogenesis in the marginal zone of 2-year-old animals (Brann and Firestein, 2010). Here, we expand the current knowledge with novel information from a commonly used AD animal model (APP/PS1 Het ), revealing an unexpected preservation of the VSE proliferative capabilities in middle age APP/PS1 Het mice.…”

“…Whereas the VSE of APP/PS1 Het mice maintained fairly stable neurogenic capabilities, senescent wild type animals showed a significant reduction in proliferative and stem cells (PCNA + and Sox2 + VSE cells) (Figure 2) which may explain the reduction of mature OMP + neurons, sustentacular Sox2 + cells and VSE volume (Figure 1 and Supplementary Figure 1). Our findings are consistent with two previous studies directly exploring the effects of natural aging in the VSE (Brann and Firestein, 2010;Mechin et al, 2021), which reported an overall thinning of the vomeronasal sensory epithelium (Mechin et al, 2021) and reduced VSE neurogenesis in 2-year-old animals (Brann and Firestein, 2010). Here, we expand this current knowledge by providing novel information on the properties of the VSE in a commonly used animal model of AD (APP/PS1 Het ), revealing an unexpected preservation of the organ and its proliferative capabilities in middle age APP/PS1 Het mice.…”

“…An elegant study by Brann and Firestein (2010) showed that the proliferative capacity of the VSE of 2-year-old animals was attenuated in comparison to young animals. More recently, Mechin et al, (2021) explored the effects of natural aging on VSE cell proliferation, finding a significant reduction in mature Olfactory Marker Protein (OMP)-expressing cells (OMP + ), indicating structural modifications of the aged VNO. However, whether these alterations in the aged VSE have any impact in odor detection and subsequent display of social behaviors, particularly in animal models of neurodegeneration, is currently unclear.…”

Natural and pathological aging distinctively impact the pheromone detection system and social behavior

“…1). Our findings are consistent with two previous studies (Brann andFirestein, 2010, Mechin et al, 2021), which reported an overall thinning of the vomeronasal sensory epithelium (Mechin et al, 2021) and reduced VSE neurogenesis in the marginal zone of 2-year-old animals (Brann and Firestein, 2010). Here, we provide novel information from a commonly used AD animal model (APP/PS1 Het ), revealing an unexpected preservation of the VSE proliferative capabilities in middle age APP/PS1 Het mice.…”

Is There a Link between Vomeronasalitis and Aggression in Stable Social Groups of Female Pigs?

“…In mice, the VNO cells were shown as the Pseudorabies virus infection after experimental intranasal inoculation [14]. More recently, always in mice, the degenerative changes induced by the ageing process were characterized [15]. Finally, the relationship between vomeronasalitis and intraspecific aggressive disorders in domestic cats has been described [16], and it is the only report that links VNO spontaneous alterations to animal behavioural changes.…”