Existence of Gαi2-Expressing Axon Terminals in the Goat Main Olfactory Bulb

In rodents, G(i2)-expressing sensory neurons (SNs) that co-express vomeronasal receptor type 1 (V1R) are specifically found in the vomeronasal organ (VNO) and project their axons to the accessory olfactory bulb (AOB). In goats, however, G(i2)/V1R-expressing SNs exist in both the VNO and the olfactory epithelium. Thus, we examined whether the G(i2)-expressing axons functionally project to the main olfactory bulb (MOB). We analyzed the expression of G(i2) in the olfactory bulb and found small G(i2)-immunoreactive clusters in the MOB. The G(i2)-immunoreactive axons in these clusters made synaptic contacts with second-order neurons in the MOB. These results suggest that some G(i2)-expressing SNs functionally project their axons to the MOB in goats.