Decreases in Pheromonal Responses at the Accessory Olfactory Bulb of Mice with a Deficiency of the α_1B or β3 Subunits of Voltage-Dependent Ca²⁺-Channels

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Pheromones affect gonadal functions and sexual behaviors. Information in regard to pheromones is received by the vomeronasal organ (VNO) and transmitted to the accessory olfactory bulb (AOB). We investigated the physiological role of the α_1B and β3 subunits of the N (neuronal)-type voltage-dependent Ca²⁺ channel in the neurotransduction in the accessory olfactory (vomeronasal) system using α_1B-deficient mice and β3-deficient mice. RT-PCR studies showed the existence of β1, β2, β3, β4, α_1A, α_1B, and α_1C subunits of voltage-dependent Ca²⁺ channels in the mouse VNO. Immunohistochemical studies showed that the α_1A, α_1B, and α_1C subunits of voltage-dependent Ca²⁺ channels exist in the sensory neurons and supporting cells of the mouse VNO. Exposure of the VNO to urine samples excreted from male mice induced lower Fos-immunoreactivity in the periglomerular (PG) cells of the AOBs in α_1B-deficient female mice than in those of wild mice. The density of Fos-immunoreactive (Fos-ir) cells after exposure to female urine samples at the periglomerular cell layer of α_1B-deficient male mice was lower than that of wild mice. Exposure of the VNO of β3-deficient female mice to male urine samples also induced low Fos-ir cells in the periglomerular cell layer of the AOB. These data suggest the importance of the α_1B and β3 subunits of the N-type voltage-dependent Ca²⁺ channel for the pheromone signal transduction system.