Immunohistochemical study of arginases 1 and 2 in the olfactory bulbs of the Korean roe deer, Capreolus pygargus

Analysis of the vomeronasal organ transcriptome reveals variable gene expression depending on age and function in rabbits

The vomeronasal organ (VNO) is a chemosensory organ specialized in pheromone detection that shows a broad morphofunctional and genomic diversity among mammals. However, its expression patterns have only been well-characterized in mice. Here, we provide the first comprehensive RNA sequencing study of the rabbit VNO across gender and sexual maturation stages. We characterized the VNO transcriptome, updating the number and expression of the two main vomeronasal receptor families, including 128 V1Rs and 67 V2Rs. Further, we defined the expression of formyl-peptide receptor and transient receptor potential channel families, both known to have specific roles in the VNO. Several sex hormone-related pathways were consistently enriched in the VNO, highlighting the relevance of this organ in reproduction. Moreover, whereas juvenile and adult VNOs showed significant transcriptome differences, male and female did not. Overall, these results contribute to understand the genomic basis of behavioural responses mediated by the VNO in a non-rodent model.

Histological and lectin histochemical studies in the vomeronasal organ of the Korean black goat, Capra hircus coreanae

We examined the localization of olfactory marker protein (OMP), protein gene product9.5 (PGP9.5), and glycan diversity in the vomeronasal organ (VNO) of the Korean black goat (Capra hircus coreanae) during the prenatal and postnatal periods using immunohistochemistry and lectin histochemistry. In fetal and 1-day-old goats, OMP was occasionally identified in receptor cells of the VNO sensory epithelium, and PGP9.5 was localized in both the sensory and non-sensory epithelia. In VNO from adult goats, OMP was abundant in the sensory epithelium and scarce in single cells of the non-sensory epithelium. These results suggest that OMP production is initiated in the VNO sensory epithelium (VNE) during the fetal stage, and that its activity is increased in adult VNO receptor cells and solitary cells in the non-sensory epithelium (VNSE). Furthermore, the free borders of the sensory epithelia were positive for 7 lectins, and 6 lectins were moderately and/or highly abundant in receptor cells. Supporting and basal cells, and nerve bundles had similar expression patterns. In VNE, 7 lectins were observed in the free border, and 6 in ciliated, goblet, and basal cells, and in gland acini. The intensities of WGA, LCA, and PNA were high in VSE receptor cells, and the intensity of PNA was high in ciliated cells of the VNSE. The other 3 lectins showed similar patterns throughout development. Collectively, these results confirm that the Korean black goat VNO starts developing during the late fetal stages and differentiates further after birth.

Olfactory Dysfunction in Autoimmune Central Nervous System Neuroinflammation

Olfactory dysfunction is an early sign of neuroinflammation of the central nervous system (CNS). Microgliosis and astrogliosis are representative pathological changes that develop during neuroinflammation of CNS tissues. Autoimmune CNS inflammation, including human multiple sclerosis, is an occasional cause of olfactory disorders. We evaluated whether gliosis and olfactory dysfunction developed in animals with experimental autoimmune encephalomyelitis (EAE), a model of human multiple sclerosis. Neuroinflammatory lesions characterized by infiltration of inflammatory cells and microglial cell activation were occasionally found in the olfactory bulbs of EAE-affected rats. Microglial activation, visualized by immunohistochemical staining of ionized calcium binding protein (Iba)-1, and astrogliosis in the olfactory bulb were also evident in the olfactory bulb of EAE rats. Inflammatory cells were found along the olfactory nerves and in the olfactory submucosa. Western blot analysis of olfactory marker protein (OMP) levels showed that OMP expression was significantly downregulated in the olfactory mucosa of EAE rats. On the buried food test, EAE-affected mice required significantly more time to find a bait pellet. Collectively, the results suggest that the olfactory dysfunction of EAE is closely linked to downregulation of OMP and the development of inflammatory foci in the olfactory system in an animal model of human multiple sclerosis.