RESUMO
We investigated a model of long-term memory in which the female mouse establishes pheromonal memory of its partner at mating. We examined the reciprocal synapses of the accessory olfactory bulb and found that pheromonal memory was associated with morphological changes in excitatory synapses in the early phase of memory acquisition and by changes in inhibitory synapses in the late phases of memory persistence. After extinction of pheromonal memory, these morphological changes were no longer present. These findings suggest that the persistence of pheromonal memory is associated with continuous and dynamic changes in the morphological plasticity of reciprocal synapses in the accessory olfactory bulb.
Assuntos
Memória/fisiologia , Bulbo Olfatório/fisiologia , Sinapses/fisiologia , Animais , Comportamento Animal , Feminino , Memória/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Eletrônica , Inibição Neural , Plasticidade Neuronal/efeitos dos fármacos , Bulbo Olfatório/efeitos dos fármacos , Bulbo Olfatório/ultraestrutura , Atrativos Sexuais/farmacologia , Comportamento Sexual Animal/fisiologia , Sinapses/classificação , Sinapses/efeitos dos fármacos , Sinapses/ultraestrutura , Fatores de TempoRESUMO
In the course of evolution, the vomeronasal organ (VNO) first appeared in amphibians. To understand the relationship between the VNO and the vomeronasal receptors, we isolated and analyzed the expression of the vomeronasal receptor genes of Xenopus laevis. We identified genes of the Xenopus V2R receptor family, which are predominantly expressed throughout the sensory epithelium of the VNO. The G-protein Go, which is coexpressed with V2Rs in the rodent VNO, was also extensively expressed throughout the vomeronasal sensory epithelium. These results strongly suggest that the V2Rs and Go are coexpressed in the vomeronasal receptor cells. The predominant expression of the Xenopus V2R families and the coexpression of the V2Rs and Go imply that V2Rs play important roles in the sensory transduction of Xenopus VNO. We found that these receptors were expressed not only in the VNO, but also in the posterolateral epithelial area of the principal cavity (PLPC). Electron microscopic study revealed that the epithelium of the PLPC is more like that of the VNO than that of the principal and the middle cavity. These results suggest that in adult Xenopus the V2Rs analyzed so far are predominantly expressed in the vomeronasal and vomeronasal-like epithelium. The analysis of V2R expression in Xenopus larvae demonstrates that V2Rs are predominantly expressed in the VNO even before metamorphosis.
